Title of Invention	"METHOD AND SYSTEM FOR RECOVERING (RUBBER-REINFORCED) POLYSTYRENE RESIN COMPOSITIONS"
Abstract	It is so arranged that high-quality (rubber reinforced) polystyrene resin compositions of various types is recovered efficiently with a small quantity of energy consumption without causing environmental pollution problems. (Rubber reinforced) polystyrene resin compositions are recovered by performing a plasticization process for plasticizing polystyrene resin (A), a coagulation process for mixing (rubber reinforced) polystyrene resin latex (B) and coagulant (C) to obtain a creamy material (D) , a mixing process for obtaining mixture (E) by supplying said creamy material (D) into an extruder in which said polystyrene resin (A) that has gone through the above plasticization process exists and mixing said plasticizing polystyrene resin (A) within said extruder, a drainage process for removing water from said mixture (E) and drain the water from said extruder, and a devolatilization process for devolatilizing said mixture after the water removal and exhausting the volatile matter from said extruder.

Title of Invention

"METHOD AND SYSTEM FOR RECOVERING (RUBBER-REINFORCED) POLYSTYRENE RESIN COMPOSITIONS"

Abstract

It is so arranged that high-quality (rubber reinforced) polystyrene resin compositions of various types is recovered efficiently with a small quantity of energy consumption without causing environmental pollution problems. (Rubber reinforced) polystyrene resin compositions are recovered by performing a plasticization process for plasticizing polystyrene resin (A), a coagulation process for mixing (rubber reinforced) polystyrene resin latex (B) and coagulant (C) to obtain a creamy material (D) , a mixing process for obtaining mixture (E) by supplying said creamy material (D) into an extruder in which said polystyrene resin (A) that has gone through the above plasticization process exists and mixing said plasticizing polystyrene resin (A) within said extruder, a drainage process for removing water from said mixture (E) and drain the water from said extruder, and a devolatilization process for devolatilizing said mixture after the water removal and exhausting the volatile matter from said extruder.

Full Text	FIELD OF TECHNOLOGY [0001] The present invention relates to a method for recovering (rubber reinforced) polystyrene resin compositions from (rubber reinforced) polystyrene resin latex. More particularly, the present invention relates to a method for recovering high-quality (rubber reinforced) polystyrene resin compositions of various types efficiently with a small quantity of energy consumption without causing the scatter of fine powder, without producing a large quantity of wastewater or without causing environmental pollution problems. Here, the "(rubber reinforced) polystyrene resin latex" refers to rubber reinforced polystyrene resin latex and/or polystyrene resin latex. In a similar way, the "(rubber reinforced) polystyrene resin compositions" refers to rubber reinforced polystyrene resin compositions and/or polystyrene resin compositions. BACKGROUND TECHNOLOGY [0002] Conventionally, the rubber reinforced polystyrene resin compositions used for the manufacture of ABS resin pellets have been manufactured by coagulating rubber reinforced polystyrene resin latex into the slurry state, and cleaning, dehydrating and then drying the slurried rubber reinforced polystyrene resin latex . However, there hve been various problems with the above conventional method, such as a large quantity of wastewater that is produced by cleaning and dehydrating processes and a large quantity of energy that is consumed, exhaust gas that is generated and fine powder that is produced and scattered in drying process. As a result, there have been various secondary problems, such as low productivity and high cost for preventing environmental pollution. In view of the above, the following methods have been proposed: (1) Coagulation -> Cleaning and dehydration -^ Squeeze-dehydration and extrusion and pelletization In this method, the rubber reinforced polystyrene resin latex is coagulated into the slurry state, cleaned and dehydrated, supplied into an extrude, squeeze-dehydrated within the extruder, extruded from the extruder and palletized. This method is advantageous in that the energy required for drying can be saved and the quantity of exhaust gas produced is small due to no drying process. However, as coagulation, dehydration and cleaning processes are required, and a large quantity of wastewater from dehydration and cleaning processes should be treated as ever. Also, there is a problem that, as there are limited resin types that are suitable to the squeeze-dehydration, this method is unable to be used for all of a wide variety of resin types. (P. 2) (2) Coagulation within extruder -> Dehydration and drying -> Pelletization (Fig. 3) In this method, rubber reinforced polystyrene resin latex is coagulated into the slurry state within an extruder 10X, dehydrated and dried, and pelletized (Refer to Patent Document 1} . Generally, resin having large molecular size or much rubber component is high in dissolution viscosity. If this method is used for processing such resin, a very large power is required for melting the resin within the extruder 10X and extruding the molten resin from the extruder 10X, and the resin temperature may become high due to a large heat generation. As a result, there is a defective case where the impact strength of the resin extruded from the extruder 10X is degraded or the color tone is deteriorated. Also, as coagulated resin is cleaned in the incompletely molten state and the water used for cleaning is drained as it is, small-sized resin particles are discharged together with the wastewater through a mechanical filter 61, there is a defective case where that large-sized equipment is required for recovering the drained resin particles. Also, as the ratio of the cylinder length/diameter (L/D) of the extruder 10X is large, there are difficulties in operation efficiency and machine maintenance. Furthermore, as both the coagulation process and the extrusion process for molten resin are performed within a single extruder, the selection of the optimum rotational speed for both the processes may be impossible. In this case, there is no choice but operate the extruder at a compromised rotational speed. As a result, there is a defective case where the extruder is unable to have stabilized operation or the resin properties are deteriorated due to an excessively high rotational speed. (3) Coagulation -> Cleaning and dehydration -> Plasticizing resin mixture, squeeze-dehydration and extrusion, and pelletization In this method, rubber reinforced polystyrene resin latex is coagulated into the slurry state, cleaned and dehydrated, and recovered as wet powder. Then, this wet powder is supplied into an extruder plasticizing polystyrene resin, mixed with the plasticized polystyrene resin within the extruder, dehydrated to remove and drain the water, devolatilized to remove the volatile matter and palletized (Refer to Patent Document 2). Like the above method (1), this method is advantageous in that the energy required for drying can be saved and the quantity of exhaust gas produced is small due to no drying process. Furthermore, compared v»lth the above method (1) , there is a case where this method is superior in that the squeeze-dehydration process has high stability and degree of freedom. However, this method still needs additional processes of coagulation, dehydration and cleaning separately, and has a problem that these additional processes need the drainage of a large quality of water. (P. 3) Patent Document 1: USP 3993292 Patent Document 2: JP 3597070 B DISCLOSURE OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION [0003] The objective of the present invention is provide a method for recovering high-quality (rubber reinforced) polystyrene resin compositions of various types efficiently with a small quantity of energy consumption without causing the scatter of fine powder, without producing a large quantity of wastewater, without causing environmental pollution problems or without adding processes of coagulation, dehydration and cleaning separately. MEANS FOR SOLVING THE PROBLEMS [0004] The present invention has features as described in [I] through [9] below: [1] Feature I: A method for recovering (rubber reinforced) polystyrene resin compositions, comprising: a plasticization process for plasticizing polystyrene resin (A); a coagulation process for mixing (rubber reinforced) polystyrene resin latex (B) and coagulant (C) to obtain a creamy material (D); a mixing process for obtaining mixture (E) by supplying the above creamy material (D) into an extruder in which the polystyrene resin (A) that has gone through the above plasticization process exists and mixing the polystyrene resin (A) within the extruder; a drainage process for removing water from the above mixture (E) and drain the water from the above extruder; and a devolatilizati-n process by devolatilizing the above mixture after the water removal and exhausting the volatile matter from the above extruder; where the (rubber reinforced) polystyrene resin compositions are recovered from the above extruder by performing the above processes. Here, the "(rubber reinforced) polystyrene resin latex (B) " refers to rubber reinforced polystyrene resin latex (B) and/or polystyrene resin latex (B) . In a similar way, the "(rubber reinforced) polystyrene resin compositions" refers to rubber reinforced polystyrene resin compositions and/or polystyrene resin compositions. This way of reference is also applicable hereinafter. The creamy material (D) refers to pasty (rubber reinforced) polystyrene resin and also to (rubber reinforced) polystyrene resin that will not decomposed into solid and liquid even if it i§ left statically for a long time (e.g., one day) under the room-temperature conditions. As there is no water decomposed as of the time when the (rubber reinforced) polystyrene resin latex (B) is coagulated into the creamy material (D) , the creamy material (D) can be mixed in good condition with the polystyrene resin (A) that has gone through the plasticization process. (P. 4) [2] Feature 2: A method for recovering (rubber reinforced) polystyrene resin compositions as described in the Feature I, where the above plasticization process is performed within the above extruder on the upstream side from the supply position of the above creamy material (D). This recovering method for recovering can be materialized by using a recovering system as exemplified in Fig. 2. [3] Feature 3: A method for recovering (rubber reinforced) polystyrene resin compositions as described in the Feature 1, where the above plasticized polystyrene resin (A) that has gone through the above plasticization process in a plasticizing system is supplied into the above extruder on the upstream side from the supply position of the above creamy material (D). This recovering method can be materialized by using a recovering system as exemplified in Fig. 1. [4] Feature 4: A method for recovering (rubber reinforced) polystyrene resin compositions as described in any of the Features 1 through 3, where the coagulation temperature in the above coagulation process is (Tm-70)°C or more when the Vicat softening temperature of the above (rubber reinforced) polystyrene resin in the latex (B) is Tm°C. If the coagulation temperature is under (Tm-70)°C, there will be much non-creamy part in the mixture of the polystyrene resin latex (B) and coagulant (C). Consequently, there will be much part that cannot be mixed in good condition with the polystyrene resin (A) that has gone through the plasticization process. [5] Feature 5: A method for recovering (rubber reinforced) polystyrene resin compositions as described in any of the Features 1 through 4, where the concentration of the solid content of the creamy material (D) obtained from the above coagulation process and supplied into the extruder is in a range from 15 to 40wt%. (P. 5) If the concentration of the solid content of the creamy material (D) is under 15wt%, there could be much non-creamy, separated water in the mixture of the polystyrene resin latex (B) and coagulant (C). Consequently, there could be much part that cannot be mixed in good condition with the polystyrene resin (A) that has gone through the plasticization process. If the concentration of the solid content of the creamy material (D) is over 40wt%, the viscosity will be too high to supply the mixture of the polystyrene resin latex (B) and coagulant (C) into the polystyrene resin (A) that has gone through the plasticization process. [6] Feature 6: A method for recovering (rubber reinforced) polystyrene resin compositions as described in any of the Features 1 through 4, where the cleaning water of 100°C or more is supplied into the above extruder on the downstream side from the supply position of the above creamy material (D) , and the water in the above cleaning water and above mixture (E) is drained from the above extruder through a biaxial screw type mechanical filter. [7] Feature 7: A method for recovering (rubber reinforced) polystyrene resin compositions as described in he Feature 6, where a gas-liquid segregating tank is provided behind the above mechanical filter and the water is drained while the pressure of the gas phase part is being controlled within the gas-liquid segregating tank. [8] Feature 8: An system for recovering (rubber reinforced) polystyrene resin compositions, comprising: a main extruder; a sub extruder for plasticizing polystyrene resin; and a coagulator; where the above extruder is equipped with a first supply port for the sub extruder in the position of the uppermost stream side, equipped with a second supply port for the above coagulator on the downstream side from the first supply port, and equipped with a water supply port for cleaning water, a drain port for cleaning water and a devolatilization port for removing volatile matter; the above first supply port is connected with a discharge port of the sub extruder; the above second .upply port is connected with a discharge port of the coagulator; the polystyrene resin that has been plasticized within the above sub extruder is supplied from the above first supply port into the above main extruder, the (rubber reinforced) polystyrene resin creamed within the above coagulator is supplied from the above second supply port and mixed with the polystyrene resin, the mixture is cleaned with the cleaning water supplied from the above water supply port while the mixture is being molten within the above main extruder, the water after the cleaning is drained from the above drain port through a mechanical filter, and the mixture with the water drained is devolatilized under negative pressure and the volatile matter is discharged from the above devolatilization port. (P. 6) An example of this recovering system is shown in Fig. I. [9] Feature 9: An system for recovering (rubber reinforced) polystyrene resin compositions as described in the Feature 8, where a gas-liquid segregating tank is provided behind the above mechanical filter and a drainer is provided for draining the water while the pressure of the gas-phase part is being controlled within the gas-liquid segregating tank. EFFECT OF THE INVENTION [0005] According to the method for recovering (rubber reinforced) polystyrene resin compositions as described in the Feature 1, the plasticization process for plasticizing polystyrene resin (A), the coagulation process for mixing (rubber reinforced) polystyrene resin latex (B) and coagulant (C) to obtain a creamy material (D) , the mixing process for obtaining mixture (E) by supplying the creamy material (D) into an extruder in which the polystyrene resin (A) that has gone through the above plasticization process exists and mixing the plasticizing polystyrene resin (A) within the extruder, the drainage process for removing water from the above mixture (E) and drain the water from the above extruder, and the devolatilization process by devolatilizingmixture after the above water removal and exhausting the volatile matter from the above extruder are performed to recover the (rubber reinforced) polystyrene resin compositions from the above extruder . Therefore, even if large-scaled equipment is not used, high-quality (rubber reinforced) polystyrene resin compositions of various types can be recovered efficiently with a small quantity of energy consumption without causing any environmental pollution problem. According to the method as described in the Feature 2 for recovering (rubber reinforced) polystyrene resin compositions as described in the Feature 1, the above plasticization process is performed within the above extruder on the upstream side from the supply position of the above creamy material (D) . Therefore, there is no need to provide any equipment separately for plasticizing the polystyrene resin (A). According to the method as described in the Feature 3 for recovering (rubber reinforced) polystyrene resin compositions as described in the Feature 1, the above plasticization process is performed within a plasticizing system and the plasticized polystyrene resin (A) is supplied into the above extruder on the upstream side from the supply position of the above creamy material (D). Therefore, the plasticization of the polystyrene resin (A) and the mixing process for mixing and melting the above plasticized polystyrene resin (A) and the slurry (creamy material) (D) can be performed in separate systems by individually setting the optimum conditions. E'jr this reason, high-quality (rubber reinforced) polystyrene resin compositions of more various types can be recovered. (P. 7) According to the method as described in the Feature 4 for recovering (rubber reinforced) polystyrene resin compositions as described in any of the Features I through 3, the coagulation temperature in the above coagulation process is (Tm-70)°C or more when the Vicat softening temperature of the above (rubber reinforced) polystyrene resin in the latex (B) is Tm°C. Therefore, the plasticized polystyrene resin (A) and the creamy material (D) can be mixed together in good condition. According to the method as described in the Feature 5 for recovering (rubber reinforced) polystyrene resin compositions as described in any of the Features 1 through 4, the concentration of the solid content of the creamy material (D) obtained from the above coagulation process and supplied into the extruder is in a range from 15 to 40wt%. Therefore, the plasticized polystyrene resin (A) and the creaky material (D) can be mixed together in good condition. According to the method as described in the Feature 6 for recovering (rubber reinforced) polystyrene resin compositions as described in any of the Features 1 through 4, the cleaning water of 100°C or more is supplied into the above extruder on the downstream side from the supply position of the above creamy material (D) , and the water in the above cleaning water and above mixture (E) is drained from the above extruder through the biaxial screw type mechanical filter. Therefore, water containing little resin compositions can be removed in good condition from the mixed and molten material of the plasticized polystyrene resin (A) and creamy material (D). According to the method as described in the Feature 7 for recovering (rubber reinforced) polystyrene resin compositions as described in the Features 6, the gas-liquid segregating tank is provided behind the above mechanical filter and the water is drained while the pressure of the gas phase part is being controlled within the gas-liquid segregating tank. Therefore, when the resin and the water are separated from each other within the extruder, the water can be separated as liquid under pressure without being vaporized. According to the system for recovering (rubber reinforced) polystyrene resin compositions as described in the Feature 8, a specific example of the system for realizing the recovering method as described in the Feature 3 (and the Features 4 through 6 referring to the Feature 3) can be provided. According to the system for recovering (rubber reinforced) polystyrene resin compositions as described in the Feature 9, a specific example of the system for realizing the recovering method as described n the Feature 7 can be provided. BRIEF EXPLANATION OF DPAWINGS [0006] Fig. 1 is an explanatory schematic of the recovering system used for manufacturing pellets of an embodiment according to the Feature 3; Fig. 2 is an explanatory schematic of the recovering system according to the Feature 2 of the present invention; Fig. 3 is an explanatory schematic of the (conventional) recovering system used for manufacturing pellets of a comparative example; and (P. 8) Fig. 4 is an explanatory schematic of the system of Fig. 1, where the sub extruder 20, the coagulator 30 and the main extruder 10 are illustrated simplistically and the part before the sub extruder 20, the part before the coagulator 30 and the part behind the mechanical filter are concealed. EXPLANATION OF NUMERALS [0007] 10 Main extruder of the recovering system according to the present invention 10B Main extruder of the recovering system according to the present invention 10X Extruder of the conventional recovering system 20 Sub extruder 30 Coagulator AVAILABLENESS IN INDUSTRY [0008] 1. Raw Materials and Conditions: (a) Polystyrene resin (A) As the polystyrene resin (A) , hard-resin like polymers, such as polystyrene, styrene-methyl methacrylate (MS resin), styrene-acrylonitrile copolymer (AS resin), styrene-acrylonitrile- methacrylate (MAS resin) and styrene-acrylonitrile-N-phenylmaleimide, and resin like polymers, such as acrylonitrile-butadiene-styrene copolymer (ABS resin), acrylonitrile-ethylene-polypropylene rubber- styrene resin (AES resin), methyl methacrylate-butadiene-styrene resin (MBS resin), methyl methacrylate-acrvlonitrile-butadiene-styrene resin (MABS resin), high-impact polystyrene resin (HIPS resin) and acrylic rubber denatured styrene-acrylonitrile resin (AAS resin), can be named. When AS resin is used as the polystyrene resin (A) to be a matrix body for adjusting the product properties, the temperature of the plasticized AS resin is in a range from 100 to 200°C, preferably from 110 to 160 °C. (b) (Rubber reinforced) polystyrene resin latex (B) (P. 9) As the (rubber reinforced) polystyrene resin latex (B) , the following polymer latex obtained by emulsion polymerization can be named: rubber-like polymers, such as styrene-butadiene rubber (SBR), hard-resin like polymers, such as polystyrene, styrene-methyl methacrylate (MS resin), styrene-acrylonitrile copolymer (AS resin), styrene-acrylonitrile- methacrylate (MAS resin) and styrene-acrylonitrile-N-phenylmaleimide, and resin like polymers, such as acrylonitrile-butadiene-styrene copolymer (ABS resin), ethylene-polypropylene denatured styrene-acrylonitrile resin (AES resin), methyl methacrylate-butadiene-styrene resin (MBS resin), methyl methacrylate-acrylonitrile-butadiene-styrene resin (MASS resin), high-impact polystyrene resin (HIPS resin) and acrylic rubber denatured styrene-acrylonitrile resin (AAS resin), can be named. The recovering method for the (rubber reinforced) polystyrene resin compositions according to the present invention is useful for mixing resin latex obtained by the emulsion polymerization method or by re-emulsifying resin with resin to be combined for adjusting or improving the physical properties, appearance and other performance . Specifically, as the polystyrene resin (A) or (rubber reinforced) polystyrene resin latex (B), AS resin, ABS resin latex, MAS resin latex, MABS resin latex, AS resin or ASA resin latex, AS resin or AES rein latex, AS resin or AS resin latex, etc. can be named. When ABS resin latex is used as the (rubber reinforced) polystyrene resin latex (B) , the resin concentration should preferably be in a range from 25 to 45wt% and the amount of addition of the coagulant (C) should preferably be in a range from 1 to lOpts.wt to lOOpts.wt of ABS resin. Thereby, by the mixture and coagulation of the (rubber reinforced) polystyrene resin latex (B) and coagulant (C) at these ratios, the concentration of the solid content of the creamy material (D) can be adjusted to a range from 15 to 40wt%, preferably from 20 to 40wt%, and more preferably from 25 to 35wt%. If the concentration of the solid content of the creamy material (D) is less than 15wt%, there could be much non-creamy, separated water in the mixture of the (rubber reinforced) polystyrene resin latex (B) and coagulant (C), and, as a result, there will be much part that cannot be mixed in good condition with the polystyrene resin (A) that has gone through the above plasticization process . If the concentration of the solid content of the creamy material (D) is over 40wt%, the viscosity will be so much that it will be difficult for the mixture of the (rubber reinforced) polystyrene resin latex (B) and coagulant (C) to be supplied into the polystyrene resin (A) that has gone through the plasticization process. When the concentration of the solid content of the creamy material (D) is in a favorable range from 20 to 40wt%, the mixture with the polystyrene resin (A) that has gone through the plasticization process is in good condition. When solid content concentration of the creamy material (D) is within a more favorable range from 25 to 35wt%, the mixture with the polystyrene resin (A) that has gone through the plasticization process is in better condition. (P. 10) (c) Coagulant (C) As the coagulant (C) , coagulant usually used to coagulate the polymer latex can be used. For example, inorganic acids, such as hydrochloric acid, sulfuric acid and nitric acid, organic acids, such as acetic acid and formic acid, and metal salts of these acids can be named. As the metal salts, inorganic salts, such as calcium chloride, aluminum chloride, aluminum sulfate and magnesium sulfate, and organic salts, such as calcium acetate and magnesium acetate, can be named, for instance. Although the metal salt may be used as solid or dissolved in water or the like, it is preferable that the metal salt should be used as a water solution of 3 to 25wt%. The above coagulant may be used independently as one type of coagulant or in combination with other two or more types of coagulants. The amount of addition of the coagulant (C) is determined by taking the concentration of the solid content of the (rubber reinforced) polystyrene resin latex (B) and the flocculation value of the (rubber reinforced) polystyrene resin into consideration. Normally, the amount of addition of the coagulant (C) is 1 to lOpts.wt or preferably 1 to Spts.wt to lOOpts.wt of the (rubber reinforced) polystyrene resin. If the amount of addition of the coagulant (C) is less than Ipts.wt, the (rubber reinforced) polystyrene resin latex (B) could not be coagulated sufficiently. In this case, as described above, there could be much non-creamy part in the mixture of the (rubber reinforced) polystyrene resin latex (B) and coagulant (C). Consequently, there could be much part that cannot be mixed in good condition with the polystyrene resin (A) that has gone through the plasticization process. If the amount of addition of the coagulant (C) is over lOpts.wt, as the necessary amount of the coagulant (C) will be exceeded, waste could be caused. Also, as described above, the viscosity will be so much that it could be difficult for the mixture of the (rubber reinforced) polystyrene resin latex (B) and coagulant (C) to be supplied into the polystyrene resin (A) that has gone through the plasticization process. Here, the above "flocculation value" refers to the lowest concentration (concentration after mixing) that results in a precipitate when the (rubber reinforced) polystyrene resin latex (B) having a specified solid content concentration and the coagulant (C) having a different solid content concentration ^ire mixed together, left for a specified lapse of time, and precipitation is confirmed, (d) Coagulation temperature (P. ID The coagulation temperature at which the creamy material (D) can be obtained by mixing the (rubber reinforced) polystyrene resin latex (B) and the coagulant (C) is (Tm - 70)°C or more when the Vicat softening temperature of the (rubber reinforced) polystyrene resin in the latex (B) is Tm °C. If the coagulation temperature is lower than (Tm - 70)°C, as the coagulated material will not solidified into the paste state but remain as liquid having low viscosity, the coagulated material could not be mixed with the polystyrene resin (A) that has gone through the plasticization process. The upper limit of the coagulation temperature is determined by a restrictive condition that the (rubber reinforced) polystyrene resin latex (B) should be heated up stably, which is approx. 90 °C. When the (rubber reinforced) polystyrene resin latex (B) and the coagulant (C) are mixed and coagulated together into the creamy material (D) and then the creamy material (D) is supplied into an extruder containing the polystyrene resin (A) that has gone through the plasticization process, the temperature of the mixture is determined by the compounding ratio of the creamy material (D) coagulated at (Tn - 70) °C or more with the polystyrene resin (A) of Tn°C to (Tn + 100) °C that has gone through the plasticization process when the Vicat softening temperature of the polystyrene resin (A) is Tn°C. However, it is preferable that this temperature should not be lower than Tn°C. (e) Cleaning water In the mixing process in which the polystyrene resin (A) that has gone through the plasticization process and the creamy material (D) are mixed together, the mixed and molten resin may be supplied with high-temperature water of 100°C or more under high pressure or steam of 100 to 200°C as cleaning water for cleaning polymerization auxiliary, such as emulsifying agent, the coagulant (D) , etc. It may also so arranged that the water is separated from the mixture (E) and drained together with the above cleaning water in the later drainage process. When high-temperature, high-pressure water or steam is supplied as described above, the coagulated material in the creamy material (D) can be heated and the plasticization can be promoted as a resultant effect. The amount (mass) of supply of this high-temperature, high-pressure water or steam should preferably be 2 times or less of that of the resin. The temperature of the steam should preferably be in a range from 110 to 180°C and should more preferably be in a range from 120 to 160°C. If the temperature of the steam is lower than 110°C, as the heat energy will be too small, there will be a problem that the resin is not plasticized sufficiently. If the temperature of steam is higher than 180°C, as the steam pressure will be too high, there will be a problem that high-pressure equipment is required and handling is too difficult, (f) Mixing ratio As to the mixing ratio of the polystyrene resin (A) and (rubber reinforced) polystyrene resin latex (B) is, when the (B) is rubber reinforced polystyrene resin latex, the content of the rubber component in the resin composition after the mixing should preferably be in a range from 10 to 35wt%. When the (B) contains no rubber component, the content of the (B) component in the resin composition after the mixing should preferably be in a range from 10 to 80wt%. (P. 12) 2. Recovering system [0010] A recovering system to embody the present invention will be described by using Figs. 1, 2 and 4 and by referring to Fig. 3, though the present invention is not limited to Figs. 1, 2 and 4. Also, in this description, AS resin will be exemplified as the polystyrene resin (A) and ABS resin latex will be exemplified as the rubber reinforced polystyrene resin latex (B) , though the exemplification is not be limited to these resins. Recovering system of Fig. 1 Firstly, a recovering system as shown in Fig. 1 will be described. This recovering system is used in the embodiments 1 through 3 described later. This recovering system is equipped with a main extruder 10, a sub extruder 20 for plasticizing the polystyrene resin (A), and a coagulator 30 for mixing the rubber reinforced polystyrene resin latex (B) and the coagulant (C) together into the creamy state. The main extruder 10 is of biaxial engagement type with .the screw diameter of 40mm, the cylinder length/diameter (L/D) ratio of 40, the motor rating of 75kW and the maximum rotational speed of 700 rpm. The sub extruder 20 is of biaxial engagement type with the screw diameter of 30mm, the cylinder length/diameter (L/D) ratio of 18, the motor rating of 37kW and the maximum rotational speed of 900 rpm. The sub extruder 20, as the cylinder length/diameter (L/D) ratio thereof is small and the boost pressure to the main extruder is small, can realize ultrahigh-speed rotation and high-flow running, and may be comparatively small in size. The coagulator 30 is of biaxial engagement type with the screw diameter of 30mm, the cylinder length/diameter (L/D) ratio of 8, the motor rating of 1.5kW and the maximum rotational speed of 120 rpm. The main extruder 10 is equipped with a first supply port 101 for the sub extruder 20 on the uppermost stream side, a second supply port 102 for the coagulator 30 is on the downstream side from the first supply port 101, a supply port 103 for cleaning water, a drain port 104 for cleaning water and a plurality of devolatilization ports 105a and 105b for removing volatile matter. Located at the front edge of the main extruder 10 is a die plate of 5(pu20 holes (provided with 20 through-holes of 5mm in diameter (5cp) each) . To the first supply port 101 is connected a delivery port of the sub extruder 20, and the second supply port 102 is connected a delivery port of the coagulator 30. To the supply port 103 is connected a supply pipe for cleaning water (or steam) , to a drain port 104 is connected a mechanical filter 41, and to the devolatilization ports 105a and 105b are connected vacuum suction machines (vents) 43 and 43. Incidentally, the above drain port 104 and mechanical filter 41 may be plural each, i.e., may be arranged plurally in the direction along the resin advancement within the main extruder 10. The above devolatilization ports 105a and 105b and vacuum suction machines 43 and 43 are shown in 2 locations and units, respectively, in Fig. 1, but may be in 3 or more locations and units, respectively. (P. 13) [0011] Into the sub extruder 20 are supplied AS resin, which is the polystyrene resin (A) , and additive, and the AS resin and the additive are molten (plasticized) therein. The matrix body of this plasticized molten state or semi-molten state is supplied from the supply port 101 into the main extruder 10. As shown in Fig. 4, into the coagulator 30 is supplied the ABS resin latex (= rubber reinforced polystyrene latex (B)) in sequence under the pressure of a pump 303, where the ABS resin latex is supplied externally into the system, emulsified and polymerized within a reactor 301 and tapped temporarily within a tank 302. Also, into the coagulator 30 is supplied the coagulant (C) in sequence. The ABS resin latex and coagulant supplied into the coagulator 30 are made creamy while being pushed forward within a cylinder by a screw. This creamy material is pushed out into the main extruder 10 under the pressure of the above pump 303, i.e., made contact and mixed with the plasticized AS resin (= polystyrene resin (A)). In this way, the AS resin (= polystyrene resin (A) ) and the coagulated ABS resin latex (= creamy material (D) ) are mixed together within the main extruder 10 into the molten state. To this mixture in the molten state is supplied high-temperature, high-pressure cleaning water (or steam) from the supply port 103. This cleaning water is drained from the drain port 104 through the mechanical filter 41 together with the water contained in the above creamy material (D). Behind the mechanical filter 41 is provided a gas-liquid segregating tank 411 as shown in Fig. 4. To a drain line of this gas-liquid segregating tank 411 is provided a control valve 412a. The degree of opening/closing of the control valve 412a, i.e., drainage rate, is controlled by a level controller 412 so that the liquid level within the gas-liquid segregating tank 411 can be maintained to a specified level. Also, to an exhaust line of the gas-liquid segregating tank 411 is provided a control valve 415a. The degree of opening/closing of the control valve 415a, i.e., exhaust rate, is controlled by a level controller 415 so that the pressure of gas-phase part within the gas-liquid segregating tank 411 can be maintained to a specified pressure. Here, the specified pressure to be maintained at the gas-phase part is pressure to maintain the pressure under which the water is separated and removed from within the main extruder 10 through the mechanical filter 41 to pressure at or above the steam pressure of the water at the then temperature. This pressure enables the water separation in the liquid state without being evaporated. Incidentally, from the water drained through the control valve 412a is recovered an inconsiderable quantity of leaked resin by an auto filter 413. This leaked resin is returned to the inlet of the coagulator 30 by a pump through a fine powder recovery tank 414. Also, the filtrate from which the resin was removed by the auto filter 413 is drained. (P. 14) The mixture with the above cleaning water and water contained in the creamy material (D) removed in this way is vacuum-sucked by the vacuum suction machines 43, and-thereby the volatile matter is exhausted from the devolatilization ports 105a and 105b. The mixture dewavered and then devolatilized in this way is discharged in the strand state from the die plate located at the front edge of the main extruder 10, cooled within a cooling tank 71 and cut by a cutter 72 into pellets. From the pellets is removed fine extraneous matter by a vibrating screen 73. Then, the pellets are recovered by a cyclone separator. [0012] Recovering system of Fig. 2 Secondly, a recovering system as shown in Fig. 2 will be described. As the recovering system of Fig. 2 is almost the same as the recovering system of Fig. 1, the same compositions will be allocated with the same numerals and description will be given mainly to different compositions. Incidentally, that each mechanism as shown in Fig. 4 is provided in the coagulator 30 and the mechanical filter 41 is also the case with the recovering system of Fig. 1. The recovering system of Fig. 2 is devoid of the sub extruder 20 of Fig. 1, i.e., the system configuration has been simplified. According to the recovering system of Fig. 2, the matrix body (AS resin and additive) is p'asticized in the uppermost area of a main extruder 10B, and a supply port 102 for the coagulator 30 is provided in an area where this plasticized matrix body exists. Due to this configuration, the cylinder length of the main extruder 10B of Fig. 2 is longer than the cylinder length of the main extruder 10 of Fig. 1. [0013] Recovering system of Fig. 3 (Recovering system of comparative example) A recovering system of Fig. 3, which is not a system to realize the recovering method according to the present invention, will be described briefly, as this system will be referred to as a comparative example later. According to the recovering system of Fig. 3, a main extruder 10X is equipped with a plurality of supply ports (not illustrated) for supplying cleaning steam and a plurality of drain ports (not illustrated) for draining cleaning water, and furthermore equipped with a plurality of mechanical filters 61 and vacuum suction machines 43. (P. 15) The main extruder 10X is of biaxial non-engagement type, (the same non-engagement type as that employed in Patent Document 1) with the screw diameter of 40mm, the cylinder length/diameter (L/D) ratio of 72, the motor rating of 75kW and the maximum rotational speed of 900 rpm. According to the recovering system of Fig. 3, raw materials (ABS resin latex and coagulant) are supplied into the main extruder 10X, plasticized while being pushed forward, supplied with cleaning steam and cleaned therewith. The condensed cleaning steam is drained, de volatilized and drained. As the raw materials are molten and cleaned and the cleaning water is devolatilized within the same cylinder, it is impossible to select the optimum rotational speeds independently for these processes. For this deficit, it is possible that each process cannot be controlled optimally and the quality of the discharged resin is not sufficient. For example, there could be problems that, for example, the molten resin temperature is too high, the resin degradation (molecular cut) is facilitated, the MFR is increased too much and the impact strength is decreased and the bL (tinge of yellow) is increased. Another problem could be complexity that the amount of rubber component has to be adjusted in a post-process, as it could not be adjusted by the matrix body. EMBODIMENT [0014] Hereinafter, the present invention will be specifically described further by referring to some embodiments, though the present invention is not limited to these embodiments. In the description of the embodiments, "parts" and "%" are based on the mass, unless otherwise specified. The evaluations referred to in the embodiments are va^aes measured as described below: [Evaluation method] (1) MFR: Measured at the temperature of 220°C and under the load of 98N in accordance with IS01133. (2) Charpy impact strength: The obtained resin pellets were formed on an injection molding machine (Niigata Engineering NN30B), and the impact strength was measured in accordance with IS0179. (3) Color tone: A test specimen of 3.2x4080mm was formed on the above injection molding machine, and the color tone was measured with a color-difference meter (Gardner TCS-II (light source C, Reflection method d-8)). [Raw materials] (1) Polystyrene resin (A): SANREX SAN-C (Techno Polymer) (Melt flow rate: 25g/10 min (220°C, 98N), AN content: 26%) was used. (2) (Rubber reinforced) polystyrene resin latex (B) : (P. 16) B-l: ABS resin latex was manufactured with butadiene rubber latex 50 parts (solid content equivalent), styrene 36.5 parts and acrylonitrile 13.5 parts by using a commonly known method. The solid content of the manufactured ABS resin latex was 33%, the rubber content of the resin thereof was 50%, the AN% of the matrix part (acetone soluble part) thereof was 27%, the limiting viscosity thereof was 0.41dl/g, and the graft rate thereof was 55%. B-2: ABS resin latex was manufactured with butadiene rubber latex 40 parts (solid content equivalent), styrene 43.8 parts, and acrylonitrile 16.2 parts by using a commonly known method. The solid content of the manufactured ABS resin latex was 34.5%, the rubber content of the resin thereof was 40%, the AN% of the matrix part (acetone soluble part) thereof was 27%, the limiting viscosity thereof was 0.45dl/g, and the graft rate thereof was 62%. [Examples I through 3, Comparisons 1 and 2] Pellets of the examples 1 through 3 were manufactured by using the recovering system of Fig. 1. The details of the compositions and manufacturing process (e.g., operating conditions) of the examples 1 through 3 are shown in Table 1. Pellets of the comparisons 1 and 2 were manufactured by using the recovering system of Fig. 3. The details of the compositions and manufacturing process (e.g., operating conditions) of the comparative examples are shown in Table 2. Furthermore, the pellets of the comparisons 1 and 2 were combined with AS pellets and kneaded and pelletized in a mono-axial extruder, and thereby pellets of comparisons 11, 12 and 21 with the same rubber content as that of the examples 1 through 3 were manufactured for physical property evaluation, where the pellets of the comparison 11 are pellets with the same rubber content as that of the example 1; the pellets of the comparison 12 are pellets with the same rubber content as that of the example 2; and the pellets of the comparison 21 are pellets with the same rubber content as that of the example 3. Each pellet of the above examples 1, 2 and 3 and the comparisons 11, 12 and 21 was evaluated on quality. The evaluation results are shown in Table 3. [Evaluation results] 1) As clearly seen in Tables 1 and 2, the comparisons 1 and 2 are larger in water entraining resin recovery volume than the examples 1, 2 and 3. 2) As seen in Tables 1 and 2 as to the comparisons 11, 12 and 21, as a result of increase in the temperature of front end resin, the MFR increases as shown in Table 3, the Charpy impact strength decreases, and the tint of yellow increases and the degree of whiteness decreases as to the color tone. (P. 17) Incidentally, example pellets were manufactured by using the recovering system of Fig. 2 and compared with the comparison pellets in the same way as the above, and almost the same results were obtained. [Table 1] (Table Removed) [Table 2] (Table Removed) [Table 3] (Table Removed) FIELD OF POSSIBLE UTILIZATION IN INDUSTRY The present invention can be utilized for manufacturing high-quality (rubber reinforced) polystyrene resin compositions of various types efficiently with a small quantity of energy consumption without causing the scatter of fine powder or without producing a large quantity of wastewater or without causing environmental pollution problems. WE CLAIM: [1] A method for recovering (rubber reinforced) polystyrene resin compositions, comprising: a plasticization process for plasticizing polystyrene resin (A) ; a coagulation process for mixing (rubber reinforced) polystyrene resin latex (B) and coagulant (C) to obtain a creamy material (D); a mixing process for obtaining mixture (E) by supplying said creamy material (D) into an extruder in which said polystyrene resin (A) that has gone through said plasticization process exists and mixing said polystyrene resin (A) within said extruder; a drainage process for removing water from said mixture (E) and drain the water from said extruder; and a devolatilization process by devolatilizing said mixture after the water removal and exhausting the volatile matter from said extruder; where the (rubber reinforced) polystyrene resin compositions are recovered from said extruder by performing the above processes. [2] A method for recovering (rubber reinforced) polystyrene resin compositions according to claim 1, where said plasticization process is performed within said extruder on the upstream side from the supply position of said creamy material (D). [3] A method for recovering (rubber reinforced) polystyrene resin compositions according to claim 1, where said plasticized polystyrene resin (A) that has gone through said plasticization process in a plasticizing system is supplied into said extruder on the upstream side from the supply position of said creamy material (D) . [4] A method for recovering (rubber reinforced) polystyrene resin compositions according to any of claims 1 through 3, where the coagulation temperature in said coagulation process is (Tm-70)°C or more when the Vicat softening temperature of said (rubber reinforced) polystyrene resin in said latex (B) is Tm°C. [5] A method for recovering (rubber reinforced) polystyrene resin compositions according to any of claims 1 through 4, where the concentration of the solid content of the creamy material (D) obtained from said coagulation process and supplied into the extruder is in a range from 15 to 40wt%. [6] A method for recovering (rubber reinforced) polystyrene resin compositions according to any of claims I through 4, where the cleaning water of 100°C or more is supplied into said extruder on the downstream side from the supply position of said creamy material (D), and the water in said cleaning water and mixture (E) is drained from said extruder through a biaxial screw type mechanical filter. [7] A method for recovering (rubber reinforced) polystyrene resin compositions according to claim 6, where a gas-liquid segregating tank is provided behind said mechanical filter and the water is drained while the pressure of the gas phase part is being'controlled within the gas-liquid segregating tank. [8] A system for recovering (rubber reinforced) polystyrene resin compositions, comprising: a main extruder; a sub extruder for plasticizing polystyrene resin; and a coagulator; where said extruder is equipped with a first supply port for the sub extruder in the position of the uppermost stream side, equipped with a second supply port for said coagulator on the downstream side from the first supply port, and equipped with a water supply port for cleaning water, a drain port for cleaning water and a devolatilization port for removing volatile matter, said first supply port is connected with a discharge port of said sub extruder, said second supply port is connected with a discharge port of said coagulator, the polystyrene resin that has been plasticized within said sub extruder is supplied from said first supply port into said main extruder, the (rubber reinforced) polystyrene resin creamed within the above coagulator is supplied from said second supply port and mixed with the polystyrene resin, said mixture is cleaned with the cleaning water supplied from said water supply port while said mixture is being molten within said main extruder, the water after the cleaning is drained from said drain port through a mechanical filter, and the mixture with the water drained is devolatilized under negative pressure and the volatile matter is discharged from said devolatilization port. [9]A system for recovering (rubber reinforced) polystyrene resin compositions according to claim claim 8, where a gas-liquid segregating tank is provided behind said mechanical filter and a drainer is provided for draining the water while the pressure of the gas-phase part is being controlled within the gas-liquid segregating tank. [10] Amethod for recovering (rubber reinforced) polystyrene resin compositions,and a system for recovering (rubber reinforced) polystyrene resin compositions, substantially as herein described, particularly with reference to, and as illustrated in the foregoing examples and the accompanying figures.

Full Text

FIELD OF TECHNOLOGY
[0001]
The present invention relates to a method for recovering (rubber reinforced) polystyrene resin compositions from (rubber reinforced) polystyrene resin latex. More particularly, the present invention relates to a method for recovering high-quality (rubber reinforced) polystyrene resin compositions of various types efficiently with a small quantity of energy consumption without causing the scatter of fine powder, without producing a large quantity of wastewater or without causing environmental pollution problems. Here, the "(rubber reinforced) polystyrene resin latex" refers to rubber reinforced polystyrene resin latex and/or polystyrene resin latex. In a similar way, the "(rubber reinforced) polystyrene resin compositions" refers to rubber reinforced polystyrene resin compositions and/or polystyrene resin compositions. BACKGROUND TECHNOLOGY [0002]
Conventionally, the rubber reinforced polystyrene resin compositions used for the manufacture of ABS resin pellets have been manufactured by coagulating rubber reinforced polystyrene resin latex into the slurry state, and cleaning, dehydrating and then drying the slurried rubber reinforced polystyrene resin latex . However, there h*ve been various problems with the above conventional method, such as a large quantity of wastewater that is produced by cleaning and dehydrating processes and a large
quantity of energy that is consumed, exhaust gas that is generated and fine powder that is produced and scattered in drying process. As a result, there have been various secondary problems, such as low productivity and high cost for preventing environmental pollution.
In view of the above, the following methods have been proposed:
(1) Coagulation -> Cleaning and dehydration -^ Squeeze-dehydration
and extrusion and pelletization
In this method, the rubber reinforced polystyrene resin latex is coagulated into the slurry state, cleaned and dehydrated, supplied into an extrude, squeeze-dehydrated within the extruder, extruded from the extruder and palletized.
This method is advantageous in that the energy required for drying can be saved and the quantity of exhaust gas produced is small due to no drying process. However, as coagulation, dehydration and cleaning processes are required, and a large quantity of wastewater from dehydration and cleaning processes should be treated as ever. Also, there is a problem that, as there are limited resin types that are suitable to the squeeze-dehydration, this method is unable to be used for all of a wide variety of resin types. (P. 2)
(2) Coagulation within extruder -> Dehydration and drying ->
Pelletization (Fig. 3)
In this method, rubber reinforced polystyrene resin latex
is coagulated into the slurry state within an extruder 10X, dehydrated and dried, and pelletized (Refer to Patent Document 1} .
Generally, resin having large molecular size or much rubber component is high in dissolution viscosity. If this method is used for processing such resin, a very large power is required for melting the resin within the extruder 10X and extruding the molten resin from the extruder 10X, and the resin temperature may become high due to a large heat generation. As a result, there is a defective case where the impact strength of the resin extruded from the extruder 10X is degraded or the color tone is deteriorated.
Also, as coagulated resin is cleaned in the incompletely molten state and the water used for cleaning is drained as it is, small-sized resin particles are discharged together with the wastewater through a mechanical filter 61, there is a defective case where that large-sized equipment is required for recovering the drained resin particles.
Also, as the ratio of the cylinder length/diameter (L/D) of the extruder 10X is large, there are difficulties in operation efficiency and machine maintenance.
Furthermore, as both the coagulation process and the extrusion process for molten resin are performed within a single extruder, the selection of the optimum rotational speed for both the processes may be impossible. In this case, there is no choice but operate the extruder at a compromised rotational speed. As a result, there is a defective case where the extruder is unable
to have stabilized operation or the resin properties are deteriorated due to an excessively high rotational speed. (3) Coagulation -> Cleaning and dehydration -> Plasticizing resin mixture, squeeze-dehydration and extrusion, and pelletization
In this method, rubber reinforced polystyrene resin latex is coagulated into the slurry state, cleaned and dehydrated, and recovered as wet powder. Then, this wet powder is supplied into an extruder plasticizing polystyrene resin, mixed with the plasticized polystyrene resin within the extruder, dehydrated to remove and drain the water, devolatilized to remove the volatile matter and palletized (Refer to Patent Document 2).
Like the above method (1), this method is advantageous in that the energy required for drying can be saved and the quantity of exhaust gas produced is small due to no drying process. Furthermore, compared v»lth the above method (1) , there is a case where this method is superior in that the squeeze-dehydration process has high stability and degree of freedom. However, this method still needs additional processes of coagulation, dehydration and cleaning separately, and has a problem that these additional processes need the drainage of a large quality of water. (P. 3)
Patent Document 1: USP 3993292 Patent Document 2: JP 3597070 B DISCLOSURE OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION [0003]
The objective of the present invention is provide a method for recovering high-quality (rubber reinforced) polystyrene resin compositions of various types efficiently with a small quantity of energy consumption without causing the scatter of fine powder, without producing a large quantity of wastewater, without causing environmental pollution problems or without adding processes of coagulation, dehydration and cleaning separately. MEANS FOR SOLVING THE PROBLEMS [0004]
The present invention has features as described in [I] through [9] below: [1] Feature I:
A method for recovering (rubber reinforced) polystyrene resin compositions, comprising:
a plasticization process for plasticizing polystyrene resin (A);
a coagulation process for mixing (rubber reinforced) polystyrene resin latex (B) and coagulant (C) to obtain a creamy material (D);
a mixing process for obtaining mixture (E) by supplying the above creamy material (D) into an extruder in which the polystyrene resin (A) that has gone through the above plasticization process exists and mixing the polystyrene resin (A) within the extruder; a drainage process for removing water from the above mixture (E) and drain the water from the above extruder; and
a devolatilizati-n process by devolatilizing the above
mixture after the water removal and exhausting the volatile matter from the above extruder;
where the (rubber reinforced) polystyrene resin compositions are recovered from the above extruder by performing the above processes.
Here, the "(rubber reinforced) polystyrene resin latex (B) " refers to rubber reinforced polystyrene resin latex (B) and/or polystyrene resin latex (B) . In a similar way, the "(rubber reinforced) polystyrene resin compositions" refers to rubber reinforced polystyrene resin compositions and/or polystyrene resin compositions. This way of reference is also applicable hereinafter.
The creamy material (D) refers to pasty (rubber reinforced) polystyrene resin and also to (rubber reinforced) polystyrene resin that will not decomposed into solid and liquid even if it i§ left statically for a long time (e.g., one day) under the room-temperature conditions. As there is no water decomposed as of the time when the (rubber reinforced) polystyrene resin latex (B) is coagulated into the creamy material (D) , the creamy material (D) can be mixed in good condition with the polystyrene resin (A) that has gone through the plasticization process. (P. 4) [2] Feature 2:
A method for recovering (rubber reinforced) polystyrene resin compositions as described in the Feature I,
where the above plasticization process is performed within
the above extruder on the upstream side from the supply position of the above creamy material (D).
This recovering method for recovering can be materialized by using a recovering system as exemplified in Fig. 2. [3] Feature 3:
A method for recovering (rubber reinforced) polystyrene resin compositions as described in the Feature 1,
where the above plasticized polystyrene resin (A) that has gone through the above plasticization process in a plasticizing system is supplied into the above extruder on the upstream side from the supply position of the above creamy material (D).
This recovering method can be materialized by using a recovering system as exemplified in Fig. 1. [4] Feature 4:
A method for recovering (rubber reinforced) polystyrene resin compositions as described in any of the Features 1 through 3,
where the coagulation temperature in the above coagulation process is (Tm-70)°C or more when the Vicat softening temperature of the above (rubber reinforced) polystyrene resin in the latex (B) is Tm°C.
If the coagulation temperature is under (Tm-70)°C, there will be much non-creamy part in the mixture of the polystyrene resin latex (B) and coagulant (C). Consequently, there will be much part that cannot be mixed in good condition with the polystyrene resin (A) that has gone through the plasticization process.
[5] Feature 5:
A method for recovering (rubber reinforced) polystyrene
resin compositions as described in any of the Features 1 through
4,
where the concentration of the solid content of the creamy material (D) obtained from the above coagulation process and
supplied into the extruder is in a range from 15 to 40wt%.
(P. 5)
If the concentration of the solid content of the creamy material (D) is under 15wt%, there could be much non-creamy, separated water in the mixture of the polystyrene resin latex (B) and coagulant (C). Consequently, there could be much part that cannot be mixed in good condition with the polystyrene resin (A) that has gone through the plasticization process. If the concentration of the solid content of the creamy material (D) is over 40wt%, the viscosity will be too high to supply the mixture of the polystyrene resin latex (B) and coagulant (C) into the polystyrene resin (A) that has gone through the plasticization process. [6] Feature 6:
A method for recovering (rubber reinforced) polystyrene resin compositions as described in any of the Features 1 through
4,
where the cleaning water of 100°C or more is supplied into the above extruder on the downstream side from the supply position
of the above creamy material (D) , and the water in the above cleaning water and above mixture (E) is drained from the above extruder through a biaxial screw type mechanical filter. [7] Feature 7:
A method for recovering (rubber reinforced) polystyrene resin compositions as described in he Feature 6,
where a gas-liquid segregating tank is provided behind the above mechanical filter and the water is drained while the pressure of the gas phase part is being controlled within the gas-liquid segregating tank. [8] Feature 8:
An system for recovering (rubber reinforced) polystyrene resin compositions, comprising: a main extruder;
a sub extruder for plasticizing polystyrene resin; and a coagulator;
where the above extruder is equipped with a first supply port for the sub extruder in the position of the uppermost stream side, equipped with a second supply port for the above coagulator on the downstream side from the first supply port, and equipped with a water supply port for cleaning water, a drain port for cleaning water and a devolatilization port for removing volatile matter;
the above first supply port is connected with a discharge port of the sub extruder;
the above second .upply port is connected with a discharge
port of the coagulator;
the polystyrene resin that has been plasticized within the above sub extruder is supplied from the above first supply port into the above main extruder, the (rubber reinforced) polystyrene resin creamed within the above coagulator is supplied from the above second supply port and mixed with the polystyrene resin, the mixture is cleaned with the cleaning water supplied from the above water supply port while the mixture is being molten within the above main extruder, the water after the cleaning is drained from the above drain port through a mechanical filter, and the mixture with the water drained is devolatilized under negative pressure and the volatile matter is discharged from the above devolatilization port. (P. 6)
An example of this recovering system is shown in Fig. I. [9] Feature 9:
An system for recovering (rubber reinforced) polystyrene resin compositions as described in the Feature 8,
where a gas-liquid segregating tank is provided behind the above mechanical filter and a drainer is provided for draining the water while the pressure of the gas-phase part is being controlled within the gas-liquid segregating tank. EFFECT OF THE INVENTION [0005]
According to the method for recovering (rubber reinforced) polystyrene resin compositions as described in the Feature 1, the
plasticization process for plasticizing polystyrene resin (A), the coagulation process for mixing (rubber reinforced) polystyrene resin latex (B) and coagulant (C) to obtain a creamy material (D) , the mixing process for obtaining mixture (E) by supplying the creamy material (D) into an extruder in which the polystyrene resin (A) that has gone through the above plasticization process exists and mixing the plasticizing polystyrene resin (A) within the extruder, the drainage process for removing water from the above mixture (E) and drain the water from the above extruder, and the devolatilization process by devolatilizingmixture after the above water removal and exhausting the volatile matter from the above extruder are performed to recover the (rubber reinforced) polystyrene resin compositions from the above extruder . Therefore, even if large-scaled equipment is not used, high-quality (rubber reinforced) polystyrene resin compositions of various types can be recovered efficiently with a small quantity of energy consumption without causing any environmental pollution problem. According to the method as described in the Feature 2 for recovering (rubber reinforced) polystyrene resin compositions as described in the Feature 1, the above plasticization process is performed within the above extruder on the upstream side from the supply position of the above creamy material (D) . Therefore, there is no need to provide any equipment separately for plasticizing the polystyrene resin (A).
According to the method as described in the Feature 3 for recovering (rubber reinforced) polystyrene resin compositions as
described in the Feature 1, the above plasticization process is performed within a plasticizing system and the plasticized polystyrene resin (A) is supplied into the above extruder on the upstream side from the supply position of the above creamy material (D). Therefore, the plasticization of the polystyrene resin (A) and the mixing process for mixing and melting the above plasticized polystyrene resin (A) and the slurry (creamy material) (D) can be performed in separate systems by individually setting the optimum conditions. E'jr this reason, high-quality (rubber reinforced) polystyrene resin compositions of more various types can be recovered. (P. 7)
According to the method as described in the Feature 4 for recovering (rubber reinforced) polystyrene resin compositions as described in any of the Features I through 3, the coagulation temperature in the above coagulation process is (Tm-70)°C or more when the Vicat softening temperature of the above (rubber reinforced) polystyrene resin in the latex (B) is Tm°C. Therefore, the plasticized polystyrene resin (A) and the creamy material (D) can be mixed together in good condition.
According to the method as described in the Feature 5 for recovering (rubber reinforced) polystyrene resin compositions as described in any of the Features 1 through 4, the concentration of the solid content of the creamy material (D) obtained from the above coagulation process and supplied into the extruder is in a range from 15 to 40wt%. Therefore, the plasticized polystyrene
resin (A) and the creaky material (D) can be mixed together in good condition.
According to the method as described in the Feature 6 for recovering (rubber reinforced) polystyrene resin compositions as described in any of the Features 1 through 4, the cleaning water of 100°C or more is supplied into the above extruder on the downstream side from the supply position of the above creamy material (D) , and the water in the above cleaning water and above mixture (E) is drained from the above extruder through the biaxial screw type mechanical filter. Therefore, water containing little resin compositions can be removed in good condition from the mixed and molten material of the plasticized polystyrene resin (A) and creamy material (D).
According to the method as described in the Feature 7 for recovering (rubber reinforced) polystyrene resin compositions as described in the Features 6, the gas-liquid segregating tank is provided behind the above mechanical filter and the water is drained while the pressure of the gas phase part is being controlled within the gas-liquid segregating tank. Therefore, when the resin and the water are separated from each other within the extruder, the water can be separated as liquid under pressure without being vaporized.
According to the system for recovering (rubber reinforced) polystyrene resin compositions as described in the Feature 8, a specific example of the system for realizing the recovering method as described in the Feature 3 (and the Features 4 through 6 referring
to the Feature 3) can be provided.
According to the system for recovering (rubber reinforced) polystyrene resin compositions as described in the Feature 9, a specific example of the system for realizing the recovering method as described n the Feature 7 can be provided. BRIEF EXPLANATION OF DPAWINGS [0006]
Fig. 1 is an explanatory schematic of the recovering system used for manufacturing pellets of an embodiment according to the Feature 3;
Fig. 2 is an explanatory schematic of the recovering system according to the Feature 2 of the present invention;
Fig. 3 is an explanatory schematic of the (conventional) recovering system used for manufacturing pellets of a comparative example; and (P. 8)
Fig. 4 is an explanatory schematic of the system of Fig. 1, where the sub extruder 20, the coagulator 30 and the main extruder 10 are illustrated simplistically and the part before the sub extruder 20, the part before the coagulator 30 and the part behind the mechanical filter are concealed. EXPLANATION OF NUMERALS [0007]
10 Main extruder of the recovering system according to
the present invention
10B Main extruder of the recovering system according
to the present invention
10X Extruder of the conventional recovering system
20 Sub extruder
30 Coagulator
AVAILABLENESS IN INDUSTRY
[0008]
1. Raw Materials and Conditions:
(a) Polystyrene resin (A)
As the polystyrene resin (A) , hard-resin like polymers, such as polystyrene, styrene-methyl methacrylate (MS resin), styrene-acrylonitrile copolymer (AS resin), styrene-acrylonitrile- methacrylate (MAS resin) and styrene-acrylonitrile-N-phenylmaleimide, and resin like polymers, such as acrylonitrile-butadiene-styrene copolymer (ABS resin), acrylonitrile-ethylene-polypropylene rubber- styrene resin (AES resin), methyl methacrylate-butadiene-styrene resin (MBS resin), methyl methacrylate-acrvlonitrile-butadiene-styrene resin (MABS resin), high-impact polystyrene resin (HIPS resin) and acrylic rubber denatured styrene-acrylonitrile resin (AAS resin), can be named.
When AS resin is used as the polystyrene resin (A) to be a matrix body for adjusting the product properties, the temperature of the plasticized AS resin is in a range from 100 to 200°C, preferably from 110 to 160 °C. (b) (Rubber reinforced) polystyrene resin latex (B)
(P. 9)
As the (rubber reinforced) polystyrene resin latex (B) , the following polymer latex obtained by emulsion polymerization can be named: rubber-like polymers, such as styrene-butadiene rubber (SBR), hard-resin like polymers, such as polystyrene, styrene-methyl methacrylate (MS resin), styrene-acrylonitrile copolymer (AS resin), styrene-acrylonitrile- methacrylate (MAS resin) and styrene-acrylonitrile-N-phenylmaleimide, and resin like polymers, such as acrylonitrile-butadiene-styrene copolymer (ABS resin), ethylene-polypropylene denatured styrene-acrylonitrile resin (AES resin), methyl methacrylate-butadiene-styrene resin (MBS resin), methyl methacrylate-acrylonitrile-butadiene-styrene resin (MASS resin), high-impact polystyrene resin (HIPS resin) and acrylic rubber denatured styrene-acrylonitrile resin (AAS resin), can be named. The recovering method for the (rubber reinforced) polystyrene resin compositions according to the present invention is useful for mixing resin latex obtained by the emulsion polymerization method or by re-emulsifying resin with resin to be combined for adjusting or improving the physical properties, appearance and other performance . Specifically, as the polystyrene resin (A) or (rubber reinforced) polystyrene resin latex (B), AS resin, ABS resin latex, MAS resin latex, MABS resin latex, AS resin or ASA resin latex, AS resin or AES rein latex, AS resin or AS resin latex, etc. can be named.
When ABS resin latex is used as the (rubber reinforced) polystyrene resin latex (B) , the resin concentration should preferably be in a range from 25 to 45wt% and the amount of addition of the coagulant (C) should preferably be in a range from 1 to lOpts.wt to lOOpts.wt of ABS resin. Thereby, by the mixture and coagulation of the (rubber reinforced) polystyrene resin latex (B) and coagulant (C) at these ratios, the concentration of the solid content of the creamy material (D) can be adjusted to a range from 15 to 40wt%, preferably from 20 to 40wt%, and more preferably from 25 to 35wt%. If the concentration of the solid content of the creamy material (D) is less than 15wt%, there could be much non-creamy, separated water in the mixture of the (rubber reinforced) polystyrene resin latex (B) and coagulant (C), and, as a result, there will be much part that cannot be mixed in good condition with the polystyrene resin (A) that has gone through the above plasticization process . If the concentration of the solid content of the creamy material (D) is over 40wt%, the viscosity will be so much that it will be difficult for the mixture of the (rubber reinforced) polystyrene resin latex (B) and coagulant (C) to be supplied into the polystyrene resin (A) that has gone through the plasticization process. When the concentration of the solid content of the creamy material (D) is in a favorable range from 20 to 40wt%, the mixture with the polystyrene resin (A) that has gone through the plasticization process is in good condition. When solid content concentration of the creamy material (D) is within a more favorable range from 25 to 35wt%, the mixture with the

polystyrene resin (A) that has gone through the plasticization
process is in better condition.
(P. 10)
(c) Coagulant (C)
As the coagulant (C) , coagulant usually used to coagulate the polymer latex can be used. For example, inorganic acids, such as hydrochloric acid, sulfuric acid and nitric acid, organic acids, such as acetic acid and formic acid, and metal salts of these acids can be named. As the metal salts, inorganic salts, such as calcium chloride, aluminum chloride, aluminum sulfate and magnesium sulfate, and organic salts, such as calcium acetate and magnesium acetate, can be named, for instance. Although the metal salt may be used as solid or dissolved in water or the like, it is preferable that the metal salt should be used as a water solution of 3 to 25wt%. The above coagulant may be used independently as one type of coagulant or in combination with other two or more types of coagulants.
The amount of addition of the coagulant (C) is determined by taking the concentration of the solid content of the (rubber reinforced) polystyrene resin latex (B) and the flocculation value of the (rubber reinforced) polystyrene resin into consideration. Normally, the amount of addition of the coagulant (C) is 1 to lOpts.wt or preferably 1 to Spts.wt to lOOpts.wt of the (rubber reinforced) polystyrene resin. If the amount of addition of the coagulant (C) is less than Ipts.wt, the (rubber reinforced) polystyrene resin latex (B) could not be coagulated sufficiently.
In this case, as described above, there could be much non-creamy part in the mixture of the (rubber reinforced) polystyrene resin latex (B) and coagulant (C). Consequently, there could be much part that cannot be mixed in good condition with the polystyrene resin (A) that has gone through the plasticization process. If the amount of addition of the coagulant (C) is over lOpts.wt, as the necessary amount of the coagulant (C) will be exceeded, waste could be caused. Also, as described above, the viscosity will be so much that it could be difficult for the mixture of the (rubber reinforced) polystyrene resin latex (B) and coagulant (C) to be supplied into the polystyrene resin (A) that has gone through the plasticization process. Here, the above "flocculation value" refers to the lowest concentration (concentration after mixing) that results in a precipitate when the (rubber reinforced) polystyrene resin latex (B) having a specified solid content concentration and the coagulant (C) having a different solid content concentration ^ire mixed together, left for a specified lapse of time, and precipitation is confirmed, (d) Coagulation temperature (P. ID
The coagulation temperature at which the creamy material (D) can be obtained by mixing the (rubber reinforced) polystyrene resin latex (B) and the coagulant (C) is (Tm - 70)°C or more when the Vicat softening temperature of the (rubber reinforced) polystyrene resin in the latex (B) is Tm °C. If the coagulation temperature is lower than (Tm - 70)°C, as the coagulated material
will not solidified into the paste state but remain as liquid having low viscosity, the coagulated material could not be mixed with the polystyrene resin (A) that has gone through the plasticization process. The upper limit of the coagulation temperature is determined by a restrictive condition that the (rubber reinforced) polystyrene resin latex (B) should be heated up stably, which is approx. 90 °C.
When the (rubber reinforced) polystyrene resin latex (B) and the coagulant (C) are mixed and coagulated together into the creamy material (D) and then the creamy material (D) is supplied into an extruder containing the polystyrene resin (A) that has gone through the plasticization process, the temperature of the mixture is determined by the compounding ratio of the creamy material (D) coagulated at (Tn - 70) °C or more with the polystyrene resin (A) of Tn°C to (Tn + 100) °C that has gone through the plasticization process when the Vicat softening temperature of the polystyrene resin (A) is Tn°C. However, it is preferable that this temperature should not be lower than Tn°C. (e) Cleaning water
In the mixing process in which the polystyrene resin (A) that has gone through the plasticization process and the creamy material (D) are mixed together, the mixed and molten resin may be supplied with high-temperature water of 100°C or more under high pressure or steam of 100 to 200°C as cleaning water for cleaning polymerization auxiliary, such as emulsifying agent, the coagulant (D) , etc. It may also so arranged that the water is separated from
the mixture (E) and drained together with the above cleaning water in the later drainage process. When high-temperature, high-pressure water or steam is supplied as described above, the coagulated material in the creamy material (D) can be heated and the plasticization can be promoted as a resultant effect. The amount (mass) of supply of this high-temperature, high-pressure water or steam should preferably be 2 times or less of that of the resin. The temperature of the steam should preferably be in a range from 110 to 180°C and should more preferably be in a range from 120 to 160°C. If the temperature of the steam is lower than 110°C, as the heat energy will be too small, there will be a problem that the resin is not plasticized sufficiently. If the temperature of steam is higher than 180°C, as the steam pressure will be too high, there will be a problem that high-pressure equipment is required and handling is too difficult, (f) Mixing ratio
As to the mixing ratio of the polystyrene resin (A) and (rubber reinforced) polystyrene resin latex (B) is, when the (B) is rubber reinforced polystyrene resin latex, the content of the rubber component in the resin composition after the mixing should preferably be in a range from 10 to 35wt%. When the (B) contains no rubber component, the content of the (B) component in the resin composition after the mixing should preferably be in a range from 10 to 80wt%. (P. 12) 2. Recovering system
[0010]
A recovering system to embody the present invention will be described by using Figs. 1, 2 and 4 and by referring to Fig.
3, though the present invention is not limited to Figs. 1, 2 and
4. Also, in this description, AS resin will be exemplified as the
polystyrene resin (A) and ABS resin latex will be exemplified as
the rubber reinforced polystyrene resin latex (B) , though the
exemplification is not be limited to these resins.
Recovering system of Fig. 1
Firstly, a recovering system as shown in Fig. 1 will be described. This recovering system is used in the embodiments 1 through 3 described later. This recovering system is equipped with a main extruder 10, a sub extruder 20 for plasticizing the polystyrene resin (A), and a coagulator 30 for mixing the rubber reinforced polystyrene resin latex (B) and the coagulant (C) together into the creamy state.
The main extruder 10 is of biaxial engagement type with .the screw diameter of 40mm, the cylinder length/diameter (L/D) ratio of 40, the motor rating of 75kW and the maximum rotational speed of 700 rpm.
The sub extruder 20 is of biaxial engagement type with the screw diameter of 30mm, the cylinder length/diameter (L/D) ratio of 18, the motor rating of 37kW and the maximum rotational speed of 900 rpm. The sub extruder 20, as the cylinder length/diameter (L/D) ratio thereof is small and the boost pressure to the main extruder is small, can realize ultrahigh-speed rotation and
high-flow running, and may be comparatively small in size.
The coagulator 30 is of biaxial engagement type with the screw diameter of 30mm, the cylinder length/diameter (L/D) ratio of 8, the motor rating of 1.5kW and the maximum rotational speed of 120 rpm.
The main extruder 10 is equipped with a first supply port 101 for the sub extruder 20 on the uppermost stream side, a second supply port 102 for the coagulator 30 is on the downstream side from the first supply port 101, a supply port 103 for cleaning water, a drain port 104 for cleaning water and a plurality of devolatilization ports 105a and 105b for removing volatile matter. Located at the front edge of the main extruder 10 is a die plate of 5(pu20 holes (provided with 20 through-holes of 5mm in diameter (5cp) each) .
To the first supply port 101 is connected a delivery port of the sub extruder 20, and the second supply port 102 is connected a delivery port of the coagulator 30. To the supply port 103 is connected a supply pipe for cleaning water (or steam) , to a drain port 104 is connected a mechanical filter 41, and to the devolatilization ports 105a and 105b are connected vacuum suction machines (vents) 43 and 43. Incidentally, the above drain port 104 and mechanical filter 41 may be plural each, i.e., may be arranged plurally in the direction along the resin advancement within the main extruder 10. The above devolatilization ports 105a and 105b and vacuum suction machines 43 and 43 are shown in 2 locations and units, respectively, in Fig. 1, but may be in 3 or
more locations and units, respectively. (P. 13) [0011]
Into the sub extruder 20 are supplied AS resin, which is the polystyrene resin (A) , and additive, and the AS resin and the additive are molten (plasticized) therein. The matrix body of this plasticized molten state or semi-molten state is supplied from the supply port 101 into the main extruder 10.
As shown in Fig. 4, into the coagulator 30 is supplied the ABS resin latex (= rubber reinforced polystyrene latex (B)) in sequence under the pressure of a pump 303, where the ABS resin latex is supplied externally into the system, emulsified and polymerized within a reactor 301 and tapped temporarily within a tank 302. Also, into the coagulator 30 is supplied the coagulant (C) in sequence.
The ABS resin latex and coagulant supplied into the coagulator 30 are made creamy while being pushed forward within a cylinder by a screw. This creamy material is pushed out into the main extruder 10 under the pressure of the above pump 303, i.e., made contact and mixed with the plasticized AS resin (= polystyrene resin (A)).
In this way, the AS resin (= polystyrene resin (A) ) and the coagulated ABS resin latex (= creamy material (D) ) are mixed together within the main extruder 10 into the molten state. To this mixture in the molten state is supplied high-temperature, high-pressure cleaning water (or steam) from the supply port 103.
This cleaning water is drained from the drain port 104 through the mechanical filter 41 together with the water contained in the above creamy material (D).
Behind the mechanical filter 41 is provided a gas-liquid segregating tank 411 as shown in Fig. 4. To a drain line of this gas-liquid segregating tank 411 is provided a control valve 412a. The degree of opening/closing of the control valve 412a, i.e., drainage rate, is controlled by a level controller 412 so that the liquid level within the gas-liquid segregating tank 411 can be maintained to a specified level. Also, to an exhaust line of the gas-liquid segregating tank 411 is provided a control valve 415a. The degree of opening/closing of the control valve 415a, i.e., exhaust rate, is controlled by a level controller 415 so that the pressure of gas-phase part within the gas-liquid segregating tank 411 can be maintained to a specified pressure. Here, the specified pressure to be maintained at the gas-phase part is pressure to maintain the pressure under which the water is separated and removed from within the main extruder 10 through the mechanical filter 41 to pressure at or above the steam pressure of the water at the then temperature. This pressure enables the water separation in the liquid state without being evaporated. Incidentally, from the water drained through the control valve 412a is recovered an inconsiderable quantity of leaked resin by an auto filter 413. This leaked resin is returned to the inlet of the coagulator 30 by a pump through a fine powder recovery tank 414. Also, the filtrate from which the resin was removed by the
auto filter 413 is drained.
(P. 14)
The mixture with the above cleaning water and water contained in the creamy material (D) removed in this way is vacuum-sucked by the vacuum suction machines 43, and-thereby the volatile matter is exhausted from the devolatilization ports 105a and 105b.
The mixture dewavered and then devolatilized in this way is discharged in the strand state from the die plate located at the front edge of the main extruder 10, cooled within a cooling tank 71 and cut by a cutter 72 into pellets. From the pellets is removed fine extraneous matter by a vibrating screen 73. Then, the pellets are recovered by a cyclone separator. [0012] Recovering system of Fig. 2
Secondly, a recovering system as shown in Fig. 2 will be described. As the recovering system of Fig. 2 is almost the same as the recovering system of Fig. 1, the same compositions will be allocated with the same numerals and description will be given mainly to different compositions. Incidentally, that each mechanism as shown in Fig. 4 is provided in the coagulator 30 and the mechanical filter 41 is also the case with the recovering system of Fig. 1.
The recovering system of Fig. 2 is devoid of the sub extruder 20 of Fig. 1, i.e., the system configuration has been simplified. According to the recovering system of Fig. 2, the matrix body (AS resin and additive) is p'asticized in the uppermost area of a main

extruder 10B, and a supply port 102 for the coagulator 30 is provided
in an area where this plasticized matrix body exists. Due to this
configuration, the cylinder length of the main extruder 10B of
Fig. 2 is longer than the cylinder length of the main extruder
10 of Fig. 1.
[0013]
Recovering system of Fig. 3 (Recovering system of comparative
example)
A recovering system of Fig. 3, which is not a system to realize the recovering method according to the present invention, will be described briefly, as this system will be referred to as a comparative example later.
According to the recovering system of Fig. 3, a main extruder 10X is equipped with a plurality of supply ports (not illustrated) for supplying cleaning steam and a plurality of drain ports (not illustrated) for draining cleaning water, and furthermore equipped with a plurality of mechanical filters 61 and vacuum suction machines 43. (P. 15)
The main extruder 10X is of biaxial non-engagement type, (the same non-engagement type as that employed in Patent Document 1) with the screw diameter of 40mm, the cylinder length/diameter (L/D) ratio of 72, the motor rating of 75kW and the maximum rotational speed of 900 rpm.
According to the recovering system of Fig. 3, raw materials (ABS resin latex and coagulant) are supplied into the main extruder

10X, plasticized while being pushed forward, supplied with cleaning steam and cleaned therewith. The condensed cleaning steam is drained, de volatilized and drained. As the raw materials are molten and cleaned and the cleaning water is devolatilized within the same cylinder, it is impossible to select the optimum rotational speeds independently for these processes. For this deficit, it is possible that each process cannot be controlled optimally and the quality of the discharged resin is not sufficient. For example, there could be problems that, for example, the molten resin temperature is too high, the resin degradation (molecular cut) is facilitated, the MFR is increased too much and the impact strength is decreased and the bL (tinge of yellow) is increased. Another problem could be complexity that the amount of rubber component has to be adjusted in a post-process, as it could not be adjusted by the matrix body. EMBODIMENT [0014]
Hereinafter, the present invention will be specifically described further by referring to some embodiments, though the present invention is not limited to these embodiments. In the description of the embodiments, "parts" and "%" are based on the mass, unless otherwise specified. The evaluations referred to in the embodiments are va^aes measured as described below:
[Evaluation method] (1) MFR:

Measured at the temperature of 220°C and under the load of 98N in accordance with IS01133.
(2) Charpy impact strength:
The obtained resin pellets were formed on an injection molding machine (Niigata Engineering NN30B), and the impact strength was measured in accordance with IS0179.
(3) Color tone:
A test specimen of 3.2x40*80mm was formed on the above injection molding machine, and the color tone was measured with a color-difference meter (Gardner TCS-II (light source C, Reflection method d-8)). [Raw materials]
(1) Polystyrene resin (A):
SANREX SAN-C (Techno Polymer) (Melt flow rate: 25g/10 min (220°C, 98N), AN content: 26%) was used.
(2) (Rubber reinforced) polystyrene resin latex (B) :
(P. 16)
B-l:
ABS resin latex was manufactured with butadiene rubber latex 50 parts (solid content equivalent), styrene 36.5 parts and acrylonitrile 13.5 parts by using a commonly known method. The solid content of the manufactured ABS resin latex was 33%, the rubber content of the resin thereof was 50%, the AN% of the matrix part (acetone soluble part) thereof was 27%, the limiting viscosity thereof was 0.41dl/g, and the graft rate thereof was 55%.

B-2:
ABS resin latex was manufactured with butadiene rubber latex 40 parts (solid content equivalent), styrene 43.8 parts, and acrylonitrile 16.2 parts by using a commonly known method. The solid content of the manufactured ABS resin latex was 34.5%, the rubber content of the resin thereof was 40%, the AN% of the matrix part (acetone soluble part) thereof was 27%, the limiting viscosity thereof was 0.45dl/g, and the graft rate thereof was 62%. [Examples I through 3, Comparisons 1 and 2]
Pellets of the examples 1 through 3 were manufactured by using the recovering system of Fig. 1. The details of the compositions and manufacturing process (e.g., operating conditions) of the examples 1 through 3 are shown in Table 1.
Pellets of the comparisons 1 and 2 were manufactured by using the recovering system of Fig. 3. The details of the compositions and manufacturing process (e.g., operating conditions) of the comparative examples are shown in Table 2.
Furthermore, the pellets of the comparisons 1 and 2 were combined with AS pellets and kneaded and pelletized in a mono-axial extruder, and thereby pellets of comparisons 11, 12 and 21 with the same rubber content as that of the examples 1 through 3 were manufactured for physical property evaluation, where
the pellets of the comparison 11 are pellets with the same rubber content as that of the example 1;
the pellets of the comparison 12 are pellets with the same rubber content as that of the example 2; and

the pellets of the comparison 21 are pellets with the same rubber content as that of the example 3.
Each pellet of the above examples 1, 2 and 3 and the comparisons 11, 12 and 21 was evaluated on quality. The evaluation results are shown in Table 3. [Evaluation results]
1) As clearly seen in Tables 1 and 2, the comparisons 1 and 2 are
larger in water entraining resin recovery volume than the examples
1, 2 and 3.
2) As seen in Tables 1 and 2 as to the comparisons 11, 12 and 21,
as a result of increase in the temperature of front end resin,
the MFR increases as shown in Table 3, the Charpy impact strength
decreases, and the tint of yellow increases and the degree of
whiteness decreases as to the color tone.
(P. 17)
Incidentally, example pellets were manufactured by using the recovering system of Fig. 2 and compared with the comparison pellets in the same way as the above, and almost the same results were obtained.

[Table 1]
(Table Removed)
[Table 2]
(Table Removed)
[Table 3]
(Table Removed)
FIELD OF POSSIBLE UTILIZATION IN INDUSTRY
The present invention can be utilized for manufacturing high-quality (rubber reinforced) polystyrene resin compositions of various types efficiently with a small quantity of energy consumption without causing the scatter of fine powder or without producing a large quantity of wastewater or without causing environmental pollution problems.

WE CLAIM:
[1] A method for recovering (rubber reinforced) polystyrene resin
compositions, comprising:
a plasticization process for plasticizing polystyrene resin (A) ;
a coagulation process for mixing (rubber reinforced) polystyrene resin latex (B) and coagulant (C) to obtain a creamy material (D);
a mixing process for obtaining mixture (E) by supplying said creamy material (D) into an extruder in which said polystyrene resin (A) that has gone through said plasticization process exists and mixing said polystyrene resin (A) within said extruder;
a drainage process for removing water from said mixture (E) and drain the water from said extruder; and
a devolatilization process by devolatilizing said mixture after the water removal and exhausting the volatile matter from said extruder;
where the (rubber reinforced) polystyrene resin compositions are recovered from said extruder by performing the above processes.
[2] A method for recovering (rubber reinforced) polystyrene resin compositions according to claim 1,
where said plasticization process is performed within said extruder on the upstream side from the supply position of said creamy material (D).
[3] A method for recovering (rubber reinforced) polystyrene resin compositions according to claim 1,
where said plasticized polystyrene resin (A) that has gone through said plasticization process in a plasticizing system is supplied into said extruder on the upstream side from the supply position of said creamy material (D) .
[4] A method for recovering (rubber reinforced) polystyrene resin compositions according to any of claims 1 through 3,
where the coagulation temperature in said coagulation process is (Tm-70)°C or more when the Vicat softening temperature of said (rubber reinforced) polystyrene resin in said latex (B) is Tm°C.
[5] A method for recovering (rubber reinforced) polystyrene resin compositions according to any of claims 1 through 4,
where the concentration of the solid content of the creamy material (D) obtained from said coagulation process and supplied into the extruder is in a range from 15 to 40wt%.
[6] A method for recovering (rubber reinforced) polystyrene resin compositions according to any of claims I through 4,
where the cleaning water of 100°C or more is supplied into said extruder on the downstream side from the supply position of said creamy material (D), and the water in said cleaning water and mixture (E) is drained from said extruder through a biaxial screw type mechanical filter.
[7] A method for recovering (rubber reinforced) polystyrene resin compositions according to claim 6,
where a gas-liquid segregating tank is provided behind said mechanical filter and the water is drained while the pressure of the gas phase part is being'controlled within the gas-liquid segregating tank.
[8] A system for recovering (rubber reinforced) polystyrene resin compositions, comprising: a main extruder;
a sub extruder for plasticizing polystyrene resin; and a coagulator;
where said extruder is equipped with a first supply port for the sub extruder in the position of the uppermost stream side, equipped with a second supply port for said coagulator on the downstream side from the first supply port, and equipped with a water supply port for cleaning water, a drain port for cleaning water and a devolatilization port for removing volatile matter, said first supply port is connected with a discharge port of said sub extruder,
said second supply port is connected with a discharge port of said coagulator,
the polystyrene resin that has been plasticized within said sub extruder is supplied from said first supply port into said main extruder, the (rubber reinforced) polystyrene resin creamed within the above coagulator is supplied from said second supply port and mixed with the polystyrene resin, said mixture is cleaned with the cleaning water supplied from said water supply port while said mixture is being molten within said main extruder, the water
after the cleaning is drained from said drain port through a mechanical filter, and the mixture with the water drained is devolatilized under negative pressure and the volatile matter is discharged from said devolatilization port.
[9]A system for recovering (rubber reinforced) polystyrene resin compositions according to claim claim 8,
where a gas-liquid segregating tank is provided behind said mechanical filter and a drainer is provided for draining the water while the pressure of the gas-phase part is being controlled within the gas-liquid segregating tank.
[10] Amethod for recovering (rubber reinforced) polystyrene resin compositions,and a system for recovering (rubber reinforced) polystyrene resin compositions, substantially as herein described, particularly with reference to, and as illustrated in the foregoing examples and the accompanying figures.

Documents:

7821-delnp-2007-abstract.pdf

7821-delnp-2007-Claims-(13-03-2014).pdf

7821-delnp-2007-claims.pdf

7821-delnp-2007-Correspondence Others-(13-03-2014).pdf

7821-delnp-2007-Correspondence Others-(18-09-2013).pdf

7821-DELNP-2007-Correspondence-Others-(16-02-2009).pdf

7821-delnp-2007-correspondence-others.pdf

7821-delnp-2007-description (complete).pdf

7821-delnp-2007-drawings.pdf

7821-delnp-2007-form-1.pdf

7821-delnp-2007-form-13-(16-02-2009).pdf

7821-delnp-2007-form-2.pdf

7821-delnp-2007-form-26.pdf

7821-delnp-2007-Form-3-(18-09-2013).pdf

7821-delnp-2007-form-3.pdf

7821-delnp-2007-form-5.pdf

7821-delnp-2007-pct-304.pdf

7821-delnp-2007-Petition-137-(13-03-2014).pdf

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Patent Number

260676

Indian Patent Application Number

7821/DELNP/2007

PG Journal Number

21/2014

Publication Date

23-May-2014

Grant Date

16-May-2014

Date of Filing

10-Oct-2007

Name of Patentee

TECHNO POLYMER CO., LTD.

Applicant Address

15-5, SHINTOMI 2-CHOME, CHUO-KU,TOKYO, 1040041 JAPAN.

Inventors:

#	Inventor's Name	Inventor's Address
1	URABE, KENICHI	C/O TECHNO POLYMER CO., LTD., 15-5, SHINTOMI 2-CHOME, CHUO-KU, TOKYO, 1040041 JAPAN.

PCT International Classification Number

C08J 3/20

PCT International Application Number

PCT/JP2006/304931

PCT International Filing date

2006-03-13

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2005-072819	2005-03-15	Japan