Title of Invention	POLYMER-LATEX-RESIN-POWDER PRODUCING DEVICE, AND METHOD FOR PRODUCING A POLYMER LATEX RESIN POWDER EMPLOYING THE SAME
Abstract	Provided is an apparatus for preparing a polymer latex resin powder having a newly designed structure, in which the apparatus has a structure including coagulation and aging baths in an integrated-type reactor and the reactor has a ratio of length to diameter of 5 to 20. By using the apparatus of the present invention, coagulation and aging processes may not only be performed in a single process, but coagulation mayalso be performed in a state of a high solid content by using a small amount of a coagulant and steam during preparation of a slurry. Therefore, since a use amount of the steam for a temperature increase is small, energy costs may be reduced. Also, a slurry having a low water content and a low content of fine particles may be obtained, the water content of the polymer latex slurry may be adjusted by additional application of a mechanical force, and apparent specific gravity may be adjusted.

Title of Invention

POLYMER-LATEX-RESIN-POWDER PRODUCING DEVICE, AND METHOD FOR PRODUCING A POLYMER LATEX RESIN POWDER EMPLOYING THE SAME

Abstract

Provided is an apparatus for preparing a polymer latex resin powder having a newly designed structure, in which the apparatus has a structure including coagulation and aging baths in an integrated-type reactor and the reactor has a ratio of length to diameter of 5 to 20. By using the apparatus of the present invention, coagulation and aging processes may not only be performed in a single process, but coagulation mayalso be performed in a state of a high solid content by using a small amount of a coagulant and steam during preparation of a slurry. Therefore, since a use amount of the steam for a temperature increase is small, energy costs may be reduced. Also, a slurry having a low water content and a low content of fine particles may be obtained, the water content of the polymer latex slurry may be adjusted by additional application of a mechanical force, and apparent specific gravity may be adjusted.

Full Text	FORM 2 THE PATENTS ACT, 1970 (39 OF 1970) & THE PATENTS RULES, 2003 COMPLETE SPECIFICATION (See Section 10; Rule 13) TITLE POLYMER-LATEX-RESIN-POWDER PRODUCING DEVICE, AND A METHOD FOR PRODUCING A POLYMER LATEX RESIN POWDER EMPLOYING THE SAME APPLICANT LG CHEM, LTD. NATIONALITY: REBUBLIC OF KOREA ofLG TWIN TOWERS 20, YEOUIDO-DONG, YEONGDEUNGPO-GU SEOUL 150-721 REPUBLIC OF KOREA The following specification particularly describes the nature of the invention and the manner in which is to be performed. POLYMER-LATEX-RESIN-POWDER PRODUCING DEVICE, AND A METHOD FOR PRODUCING A POLYMER LATEX RESIN POWDER EMPLOYING THE SAME BACKGROUND [0001] This application claims the priority of Korean Patent Application No. 10-2009-0072597 filed on August 7, 2009, which is hereby incorporated by reference in its entirety into this application. [0002] The present invention disclosed herein relates to a new preparation apparatus for coagulation of a polymer latex in the preparation of a polymer latex resin powder having a high solid content of an emulsion polymerized latex and a method of preparing a polymer latex resin powder using the same, and more particularly, coagulation and aging processes are substantially performed at the same time by changing a reactor structure so as to include coagulation and aging baths in an integrated reactor, and thus, a polymer latex resin powder having a high solid content may be prepared in a very short retention time in comparison to a typical process. [0003] Coagulation of an emulsion polymerized polymer latex is performed through breaking the stability of each latex particle stabilized by means of an emulsifier by a chemical method using various coagulants or a mechanical force with application of strong shear stress. The chemical method using coagulants breaks the stability by using different coagulant according to the type of a emulsifier used for securing the stability of a latex and the method of breaking the stability by using a mechanical force is performed in which a repulsive force between emulsifiers is overcome by strong shear stress such that latex particles are agglomerated to each other. [0004] Rapid coagulation was suggested as a method of preparing a polymer latex as a powder in the emulsion polymerization process. This method allows a polymer in a latex to be agglomerated fast through breaking the stability of an emulsifier by introducing an excessive amount of an aqueous solution of a coagulant such as inorganic salt and acid. The agglomeration of polymer particles in the latex is denoted as coagulation, and the agglomerated polymer particles are denoted as a slurry. Since the agglomerated polymer particles are in a physically weak bond state, a phenomenon of easy break-up by means of external shear caused by a stirrer or the like may appear. Therefore, a primarily agglomerated slurry is heated to go through an aging process, a process of strengthening a bonding force by means of interpenetration between chains. The slurry thus formed undergoes dehydration and drying processes and a powder phase is finally obtained. [0005] With respect to the foregoing rapid coagulation in which an excessive amount of a coagulant is used, a process of agglomeration of polymer latex particles occurs very fast and in a disordered manner because the stability of the latex is broken very fast. Apparent specific gravity may decrease due to the foregoing disordered coagulation and a particle size distribution of final particles may become very broad. [0006] In a typical polymer latex resin powder, small particles having an average particle diameter of about 75 µm or less are denoted as "Fine" and large particles having an average particle diameter of about 1400 µm or more are denoted as "Coarse". The Fine may degrade the performances of dehydrator and dryer for a latex resin powder and may be a cause of generating many limitations in transfer and packaging of the powder during a process because the Fine is easily scattered in the air. The Coarse may have limitations in transfer and storage and may have low compatibility with other polymer resins. [0007] Meanwhile, FIG. 1 is a schematic diagram illustrating an apparatus for a coagulation process of preparing a polymer latex resin powder according to the related art. The apparatus has a configuration including a latex storage tank 1, a coagulation bath 2, an aging bath 3, a dehydrator 4, and a dryer 5. [0008] . When a process of preparing a polymer latex resin powder is examined with reference to FIG. 1, a polymer latex stored in the latex storage tank 1 is first added to the coagulation bath 2 through a polymer latex input line 11 and then an aqueous solution of a coagulant, such as an inorganic salt or an acid, is added to the polymer latex through a coagulant input line 12 and water is added to the coagulation bath 2 through a water supply line 13 in order to adjust a solid concentration. The added coagulant aqueous solution breaks electrostatic stabilization by means of an emulsifier and a polymer slurry may then be obtained through a coagulation process that agglomerates polymer particles in the latex. The coagulated polymer slurry is transferred to the aging bath 3 and undergoes a process of aging by being maintained at a high temperature for 40 minutes to 90 minutes. The finally obtained slurry undergoes a dehydration process in the dehydrator 4 and is dried in the dryer 5, and a final polymer powder 15 is then obtained. Most of the added coagulant is dissolved in water in the dehydrator 4 and discharged 14 therefrom. [0009] When the foregoing apparatus is used, a slurry having high viscosity is not only difficult to be stirred during preparation of a slurry having a high solid content, but transfer is also impossible because a phenomenon of agglomeration is accelerated due to a high temperature when the slurry is aged. Therefore, the-operation may be possible only under a low solid content because collection as a powder is very difficult. [0010] A multi-stage continuous coagulation and aging process was suggested in order to address the foregoing limitations. The process has advantages in that a polymer slurry having a low solid content may be effectively aged, but the process also may not be applied to a slurry having a high solid content and may be somewhat poor in terms of process efficiency because many stages must be passed through. [0011] Accordingly, a slow coagulation process, which improves powder characteristics of final particles generated by controlling a coagulation rate through a split input of a coagulant, was suggested as another method. Since coagulation occurs in a second well region having an energy barrier in the foregoing method, a coagulation rate is slow and there is room for completing redistribution of particles. Therefore, preparation of spherical particles by means of regular filling may be possible. However, an overall use amount of the coagulant is similar to that of the rapid coagulation and it is a method of performing coagulation by only using the split input. Therefore, generation of wastewater due to the excessive amount of the coagulant is inevitable and with respect to a first coagulation bath, since a small amount of the coagulant is introduced in comparison to that of the rapid coagulation, viscosity of the slurry increases. Thus, water must be added more in comparison to the rapid coagulation in order to secure flowability and a water content may be high in comparison to that of the rapid coagulation. [0012] In all the foregoing methods, the flowability of the prepared polymer latex slurry is affected by a solid content, a particle size distribution of the slurry, and a contained water content. In particular, the flowability thereof is greatly affected by the solid content. When the solid content of the slurry is more than a certain amount, the slurry becomes agglomerated because the flowability of the slurry rapidly deteriorates, and as a result, the operation may be impossible. Therefore, a large amount of water may be further added during a coagulation process in order to improve the flowability of the slurry. The large amount of the added water increases energy costs generated for heating the slurry to a coagulation temperature and an aging temperature, and also increases post-processing costs by generating a large amount of wastewater during a dehydration process. Also, the efficiency thereof may decrease because direct steam is not used but energy is transferred to the slurry by condensing water as a medium. [0013] As another method of collecting the powder from the emulsion polymerized latex, a polymer latex powder is collected by using a gas-phase spray system. This is a method of collecting a polymer latex resin having a high solid content as a spherical powder by spraying the resin onto a surface with the flow of an excessive amount of a coagulant by using an atomizer. In this case, since the polymer latex maintaining a high solid content is in contact with the coagulant, rapid coagulation is completed at the moment of contact with the coagulant and thus, high apparent specific gravity may be obtained and the collection of a spherical powder required in a slow coagulation process may be possible. However, since an excessive amount of the coagulant must be used in order to prevent the generation of an unreacted latex, the generation of a large amount of wastewater is inevitable, and since a clogging phenomenon of the atomizer occurs frequently, the foregoing method is disadvantageous in terms of process stability. [0014] Also, there has been much research controlling a particle size of the powder under the existence of an organic solvent and improving apparent specific gravity, but in these cases, the foregoing powder characteristics may only be secured by using an excessive amount of the organic solvent. [0015] As another method, there is shear coagulation, in which a slurry is prepared by agglomeration between latex particles with application of shear stress caused by a strong mechanical force. A coagulant is not used but a polymer latex slurry is prepared by the application of shear stress caused by a high-speed rotation of 4000 rpm or more. However, with respect to the emulsion polymerized polymer latex having stability secured by using an emulsifier, the residual emulsifier remains in a collected powder and thus, may adversely affect thermal stability and color during processing. SUMMARY [0016] The present invention provides a method of preparing a polymer latex powder having a high solid content as well as process characteristics being maintained in the preparation of a polymer latex powder with various methods by using a typical preparation apparatus for an emulsion polymerized polymer latex resin powder including a coagulation bath, an aging bath, a dehydration bath, and a dryer, in order to resolve various limitations of the related art. [0017] The present invention is based on observations, in which a retention time required for coagulation and aging is increased to about 30 minutes to 1 hour because typical coagulation and aging baths have separate and independent configurations and accordingly, various limitations are generated. According to the present invention, coagulation and aging processes may not only be substantially performed in one reactor at the same time and in a very short retention time by using a new preparation apparatus for coagulation of a polymer latex, in which both coagulation and aging baths are included in an integrated-type reactor and one or more barrel pins are attached to the integrated reactor, but excellent powder characteristics may be secured by using a small amount of a coagulant and direct steam. With respect to the foregoing polymer latex resin powder, various characteristics, such as a high solid content, a low water content, a high apparent specific gravity, and excellent processability, may be controlled to desired levels. [0018] Embodiments of the present invention provide a new preparation apparatus for coagulation of a polymer latex able to prepare a polymer latex resin powder having a desired high level of physical properties. [0019] In other embodiments of the present invention, a method of preparing of a polymer latex resin powder having a high solid content by using the new preparation apparatus for coagulation of a polymer latex is provided. BRIEF DESCRIPTION OF THE DRAWINGS [0020] The accompanying drawings are included to provide a further understanding of the present invention, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present invention and, together with the description, serve to explain principles of the present invention. In the drawings: [0021] FIG. 1 is a schematic drawing illustrating a typical apparatus for a coagulation process; and [0022] FIG. 2 is a schematic drawing illustrating an integrated reactor of a newly designed apparatus for preparing a polymer latex slurry according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS [0023] Preferred embodiments of the present invention will be described below in more detail with reference to the accompanying drawings. The present invention may. however, be embodied in different forms and should not be constructed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and wiJJ fully convey the scope of the present invention to those skilled in the art. [0024] An apparatus for preparing a polymer latex resin powder of the present invention includes a latex tank, a coagulation bath, an aging bath, a dehydrator, and a dryer, wherein the apparatus for preparing a polymer latex resin powder has a structure including the coagulation and aging baths in an integrated- type reactor and the reactor has a ratio of length to diameter of 5 to 20. [0025] Also, a method of preparing a polymer latex resin powder of the present invention is characterized in that coagulating and aging are not performed in two separate steps but performed at the same time in one reactor by using the new preparation apparatus for coagulation of a polymer latex. [0026] Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. [0027] The present invention relates to a method of preparing a powder having a low content of fine particles and improved apparent specific gravity through effective coagulation and aging of a slurry having a high solid content by using a newly designed apparatus in which two steps, coagulation and aging processes, are reduced to one step. [0028] FIG. 2 is a schematic drawing illustrating an integrated-type reactor including both coagulation and aging baths in a newly designed apparatus for preparing a polymer latex slurry according to the present invention, in which the newly designed apparatus has a structure including the coagulation and aging baths in an integrated-type reactor 100 and the integrated-type reactor 100 has a ratio of length L to diameter D of 5 to 20. [0029] Typically, the coagulation bath and the aging bath are included in separate reactors and thus, a polymer slurry, which is coagulated by adding a coagulant and an appropriate amount of water to a polymer latex, is transferred to the aging bath to perform a process of aging at a predetermined temperature for a predetermined time. [0030] However, in the present invention, coagulation and aging are performed at the same time in the integrated-type reactor 100. In particular, a polymer latex is added to the reactor 100 through a polymer latex input line 110 and a small amount of a coagulant and direct steam are added thereto through a coagulant input line 120 and a steam input line 130, respectively. [0031] In the integrated-type reactor 100 according to the present invention, barrel pins inserted into the inside of the reactor are fixed at the outside thereof and one or more stirrers 150 rotate in the reactor. In particular, one or more barrel pins 140a and 140b are included in any one surface of an upper or lower portion of the inside of the reactor from the outside of the integrated-type reactor 100. Also, since the internal stirrers 150 continuously rotate in a polymer slurry, the polymer slurry in preparation may be induced to be broken up well without agglomeration while the polymer slurry is in contact with the internal stirrers 150 and the barrel pins 140a and 140b. Shape of the barrel pin is not particularly limited and the barrel pins having any shape, such as circle, triangle, taper, ellipse, diamond, or quadrangle, may be used. Type of the stirrer 150 is not particularly limited and the stirrers having any type, such as paddle, screw, twin-screw, or pin, may be used. [0032] The apparatus of the present invention may adjust the viscosity of the polymer slurry by the action of the barrel pins and the internal stirrers as well as the structure of the integrated reactor, and a water content thereof may be adjusted by using a mechanical force after the preparation of a slurry having high viscosity. [0033] In the integrated-type reactor 100 having the foregoing structure, a coagulation reaction occurs near positions where polymer latex, coagulant, and steam are introduced, and an aging reaction occurs in a rear portion of the reactor. Therefore, coagulation and aging may be substantially performed at the same time in the same reactor. [0034] In particular, the integrated reactor 100 may have a ratio of length to diameter of 5 to 20 in order to perform coagulation and aging at the same time and the ratio having the foregoing range is desirable in terms of particle size control through break-up. Also, since a use amount of water is minimized and direct steam is used, heat may be effectively supplied by inducing condensation of the steam. [0035] Meanwhile, a method of preparing a polymer latex resin powder of the present invention having a high solid content by using the foregoing new preparation apparatus for coagulation of a polymer latex is characterized in that coagulating and aging are not performed in two separate steps but performed at the same time in one reactor. [0036] A polymer latex used in the present invention is an emulsion polymerized polymer latex having a solid content of 10 wt% to 90 wt% and may be a graft copolymer composed of a vinyl cyanide compound, a conjugated diene compound, and an aromatic vinyl compound. The graft copolymer is prepared by polymerizing a mixture of an aromatic vinyl compound and a monomer of a vinyl cyanide compound with a conjugated diene compound. [0037] The conjugated diene compound is selected from the group consisting of a butadiene rubber (BR), an ethylene-propylene-diene monomer rubber (EPDM), a halobutyl rubber, a butyl rubber, styrene-isoprene-styrene (SIS), and a styrene- butadiene rubber (SBR). [0038] Also, the vinyl cyanide compound is selected from the group consisting of acrylorritrile, methacrylonitrile, ethacrylonitrile, and a derivative thereof. [0039] The aromatic vinyl compound is selected from the group consisting of styrene, α-methylstyrene, α-ethylstyrene, para-methylstyrene, vinyl toluene, and a derivative thereof. [0040] A solid content of the graft copolymer is in a range of 25 wt% to 60 wt% and the solid content thereof may include 40 to 70 wt% of butadiene, 5 to 20 wt% of acrylonitrile, and 10 to 40 wt% of styrene. [0041] The polymer latex of the present invention is not limited to the graft copolymer composed of the vinyl cyanide compound, the conjugated diene compound, and the aromatic vinyl compound, and other polymer latexes including an emulsifier to maintain the stability thereof may be used. [0042] Examples of the other polymer latexes including an emulsifier to maintain the stability thereof may be a styrene polymer, a butadiene polymer, a styrene-butadiene copolymer, an alkyl acrylate polymer, an alkyl methacrylate polymer, an alkyl acrylate-acrylonitrile copolymer, an acrylonitrile-butadiene copolymer, an acrylonitrile-butadiene-styrene copolymer, an acrylonitrile-alkyl acrylate-styrene copolymer, an alkyl methacrylate-butadiene-styrene copolymer, an alkyl acrylate-alkyl methacrylate copolymer, etc. [0043] Examples of the coagulant may be a water-soluble inorganic acid, such as a sulfuric acid, a phosphoric acid, and a hydrochloric acid, or an inorganic salt such as a sulfate and a calcium salt. In general, the coagulant may be introduced more than a theoretical value required for coagulation and in the present invention, the coagulant is used in an amount range of 0.5 to 5.0 parts by weight based on 100 parts by weight of the polymer latex, may be used in an amount range of 0.5 to 3.0 parts by weight, and for example, may be used in an amount range of 0.5 to 2.0 parts by weight. That is, a polymer latex may be effectively coagulated by only a trace amount of the coagulant in the present invention. [0044] The present invention prepares a polymer latex slurry through coagulation by adding a coagulant and direct steam to the polymer latex, and when a solid content of the polymer latex used is higher than that of the polymer slurry to be prepared, a liquid phase of water may be selectively added in order to adjust the solid content. At this time, a content of the added water may be selected in a range of 5 to 500 parts by weight based on 100 parts by weight of the polymer latex in order to obtain an appropriate solid content. [0045] Therefore, coagulation and aging are performed by adding the polymer latex, a small amount of the coagulant the direct steam, and if necessary, the liquid phase of water into an integrated reactor as shown in FIG. 2. At this time, a coagulation and aging temperature may be in a range of 60°C to 100°C. In the integrated-type reactor having a structure of FIG. 2, a coagulation reaction occurs near positions where polymer latex, coagulant, and steam are introduced, and an aging reaction occurs in a rear portion of the reactor. Therefore, coagulation and aging may be substantially performed at the same time in the same reactor. [0046] Meanwhile, a retention time of the polymer slurry residing in the integrated-type reactor is in a range of 0.5 minutes to 30 minutes, may be in a range of 0.5 minutes to 10 minutes, and for example, may be in a range of 0.5 minutes to 5 minutes. Different from the case in which a long retention time of about 30 minutes to 1 hour is needed when coagulation and aging processes are separately performed by using a typical preparation apparatus as shown in FIG. 1, a slurry having excellent powder characteristics may be prepared in a very short retention time by using a newly designed apparatus in the present invention. The coagulation process is substantially completed within a range of a few seconds to 1 minute during the retention time, and aging is performed immediately after the coagulation process is finished and continuously performed until the polymer slurry is discharged outside. [0047] In the present invention, reaction may be performed in such a manner that the retention time of the polymer slurry in the coagulation and aging processes exceeds 30 minutes, but the foregoing case is not economical because a size of the apparatus will be large. [0048] A solid content of the polymer latex slurry of the present invention prepared by using the foregoing process differs according to a solid content of the polymer latex, but the solid content of the polymer latex slurry may generally be in a range of 25 wt% to 60 wt%. When the solid content is less than 25 wt%, the retention time of the slurry may not be secured because the flowability of the slurry is too high, and when the solid content is more than 60 wt%, operation may be impossible because the slurry blocks the inside of the apparatus due to a decrease in a feed force of the slurry. [0049] The polymer slurry, in which the coagulation and the aging are performed at the same time, is discharged from the integrated-type reactor and transferred to a slurry storage tank. The coagulated and aged slurry is collected as a powder through typical dehydration and drying processes. [0050] Although aging at a high temperature is required for the interpenetration between polymer chains in a typical process, a polymer slurry having a high solid content may be prepared by coagulation and aging processes in a short retention time in the present invention. High apparent specific gravity may be obtained with respect to the powder obtained through dehydration and drying because of the foregoing coagulation characteristics, and a content of fine particles may be very small. Also, since a slurry having high viscosity may be prepared according to selectively including a liquid phase of water, a water content may be adjusted by using a mechanical force of the stirrer and a powder having a low water content may be prepared. [0051] The finally prepared polymer latex resin powder according to the present invention may have a water content of 30 wt% or less and this may be desirable in terms of increasing apparent specific gravity. [0052] Also, a content of fine particles having an average particle diameter of 75 um or less in the finally prepared polymer latex resin powder according to the present invention may be 1.5 wt% or less and this may be desirable in terms of minimizing a blow-off phenomenon during the collection of the powder and maximizing product recovery efficiency. [0053] Hereinafter, examples are provided to allow for a clearer understanding of the present invention, but the following examples are merely presented to exemplify the present invention and the scope of the present invention is not limited to the following examples. [0054] Example 1 [0055] A graft copolymer composed of a vinyl cyanide compound, a conjugated diene compound, and an aromatic vinyl compound of the present invention was an acrylonitrile (AN)-butadiene (BD)-styrene (SM) copolymer having a weight percentage ratio of AN : BD : SM of 13 : 60 : 27 and had a solid content of 44%. [0056] The latex was introduced at a flow rate of 12 kg/hr into a new integrated-type reactor as shown in FIG. 2 and a diluted sulfuric acid (H2SO4) was used as a coagulant in an amount of 1.0 part by weight based on 100 parts by weight of a total polymer content. While introducing direct steam, a liquid phase of water was further mixed with a sulfuric acid corresponding to a solid content of a slurry and then introduced to adjust the solid content of the polymer latex slurry to 30%. [0057] A retention time in the newly designed integrated-type reactor was an average of 1.5 minutes, and a coagulation and aging temperature was 75°C. An aging process began immediately after a coagulation process finished and was continuously performed until the slurry was discharged outside. The coagulated slurry was discharged outside through newly designed stirrers and transferred to a slurry storage tank. The coagulated and aged slurry was collected as a polymer resin powder through dehydration and drying processes. [0058] Example 2 [0059] A polymer resin powder was prepared in the same manner as Example 1 except that a solid content of a polymer latex slurry was 35%. [0060] Example 3 [0061] A polymer resin powder was prepared in the same manner as Example 1 except that a solid content of a polymer latex slurry was 44%. [0062] Example 4 [0063] A polymer resin powder was prepared in the same manner as Example 1 except that an input amount of a coagulant used was 0.7 parts by weight based on 100 parts by weight of a polymer latex. [0064] Example 5 [0065] A polymer resin powder was prepared in the same manner as Example 1 except that an input amount of a coagulant used was 1.5 parts by weight based on 100 parts by weight of a polymer latex. [0066] Comparative Example 1 [0067] An emulsion polymerized latex was prepared by using a typical apparatus of FIG. 1. The same latex as that of Example 1 was introduced and a 10% diluted sulfuric acid was used as a coagulant in an amount of 1.0 part by weight based on 100 parts by weight of a total polymer content. A solid content of a total slurry was adjusted to 27% by further adding water in order to maintain the flowability of the slurry, and a retention time was 10 minutes and a coagulation temperature was maintained at 75°C. The coagulated slurry was transferred to an aging bath by means of an overflow method, a retention time in the aging bath was 60 minutes, and temperature thereof was maintained at 90°C. Subsequent processes were the same as those of Example 1. [0068] Comparative Example 2 [0069] An emulsion polymerized latex was prepared in the same manner as Example 1 except that the coagulant in Comparative Example 1 is used in an amount of 1.5 parts by weight based on 100 parts by weight of the polymer content. [0070] Comparative Example 3 [0071] An emulsion polymerized latex was prepared in the same manner as Example 1 except that the coagulant in Comparative Example 1 is used in an amount of 2.0 parts by weight based on 100 parts by weight of the polymer content. [0072] Water contents, apparent specific gravities, particle size distributions, and whiteness values of the polymer iatex resin powders of Examples and Comparative Examples were measured by using the following methods, and the results thereof are presented in Table 1. [0073] 1) Water content: Changes in weight were measured after completely drying at 150°C by using a moisture meter (Merrier Toledo HR83-P). [0074] 2) Apparent specific gravity: Measured in accordance with ASTM D1985. [0075] 3) Particle size distribution: Particle diameters were measured by using standard sieves and contents of fine particles having a particle diameter of 75um or less and contents of coarse particles having a particle diameter of 1400 um or more were measured. [0076] 4) Whiteness of powders: L, a, and b values were measured by using a colorimeter (Hunter Lab Co. Color Quest II). L. a, and b respectively denote values of coordinate axes representing inherent colors. L may have a value from 0 to 100, and L represents black as the value approaches 0 and white as the value approaches 100. a may be a positive or negative number with reference to 0, and a represents red as the value is greater than 0 and green as the value is smaller than 0. b may be a positive or negative number with reference to 0, and b represents yellow as the value is greater than 0 and blue as the value is smaller than 0. [0077] [Table 1] Solid content (%) Coagulant (parts by weight) Water content (wt%) Apparent specific gravity (g/ml) Fine content (wt%) Coarse content (wt%) Color L a b Example 1 30 1.0 26.10 0.32 0.7 16.3 96.37 0.16 2.35 Example 2 35 1.0 24.85 0.34 0.4 17.2 96.54 0.13 2.24 Example 3 44 1.0 21.23 0.37 0.3 18.4 96.81 0.10 2.13 Example 4 30 0.7 34.91 0.30 1.4 15.6 97.15 0.08 2.05 Example 5 30 1.5 22.97 0.33 0.9 24.2 96.31 0.16 2.47 Comparative Example 1 27 1.0 43.96 0.27 5.6 18.7 94.64 0.22 3.21 Comparative Example 2 27 1.5 34.59 0.28 4.1 23.7 94.77 0.22 3.65 Comparative Example 3 27 2.0 25.92 0.30 2.5 27.1 94.72 0.16 4.01 [0078] As shown in Table 1, according to the results of Examples of the present invention in which polymer latex slurries were prepared by using a new preparation apparatus for a polymer latex slurry, it may be confirmed that the slurry coagulated for having a higher solid content than that of Comparative Example 3 had a much lower water content, a content of fine particles was decreased, and whiteness was increased, when the same coagulant was used. [0079] With respect to the coagulation of the slurry having a high solid content, a content of fine particles significantly decreased as well as apparent specific gravity being increased. Accordingly, since post processing, such as transfer of the polymer latex resin powder and packaging of products, was facilitated and a blow-off phenomenon of the fine particles disappeared, a working environment may be improved and productivity may be increased. Also, it may be understood that the higher the solid content was, the larger the apparent specific viscosity and the smaller the content of the fine particles were. In addition, since the added water was minimized, the generation of wastewater, an environmental problem, was reduced as well as an energy saving effects being obtained, and thus, post-processing costs may be reduced. [0080] Also, when compared with the methods of Comparative Examples in which powders were prepared through separate coagulation and aging processes typically requiring a time of 1 hour or more, the new coagulation process using a slurry having a high solid content may prepare a powder having physical properties equivalent to those of a typical powder by only using a short retention time of 5 minutes or less. [0081] Further, in order to confirm physical properties of the polymer slurry powders according to the present invention, 1 wt% of a lubricant and 0.5 wt% of an antioxidant were added to 26 wt% of the obtained acrylonitrile-butadiene-styrene copolymer dry powder and 74 wt% of styrene-acrylonitrile copolymer (LG Chemical. Ltd. 92HR) as a hard matrix and mixed. The mixture was prepared as pellet forms by using a 40 O extrusion kneader at a cylinder temperature of 220°C and physical property samples were prepared by injection molding the pellets. Physical properties were measured as below by using the samples and the results thereof are presented in the following Table 2. [0082] 1) Izod impact strength (1/4" notched at 23°C, kg-cm/cm) - Measured in accordance with ASTM D256. [0083] 2) Izod impact strength (1/8" notched at 23°C, kg-cm/cm) - Measured in accordance with ASTM D256. [0084] 3) Tensile strength (50 mm/min, kg/cm ) - Measured in accordance with ASTM D638. [0085] 4) Gloss (45° angle) - Measured in accordance with ASTM D523. [0086] 5) Flow index (220°C/10 kg, g/10 min) - Measured in accordance with ASTM D123-8. [0087] 6) Flexural strength (50 mm/min, kg/cm2) - Measured in accordance with ASTM D790. [0088] [Table 2] Izod impact strength (1/4) Izod impact strength (1/8) Flow index Tensile strength Flexural strength Gloss Example 1 29.4 32.3 22.3 415 793 101.5 Example 2 29.7 32.8 22.1 413 794 101.8 Example 3 29.6 31.6 21.6 415 792 101.8 Example 4 29.1 32.1 22.1 416 791 101.4 Example 5 29.6 32.8 22.8 413 796 101.6 Comparative Example 1 28.4 28.6 22.1 414 793 101.9 Comparative Example 2 28.8 28.8 21.9 415 794 101.7 Comparative Example 3 29.0 29.2 21.6 418 794 101.4 [0089] As confirmed by the results of Table 2, when the results of physical property measurements using the powder of Example 1 prepared according to the present invention were compared with those of Comparative Example 1, it may be confirmed that impact strength slightly increased even though the content of the coagulant used was the same, and flow index, tensile strength, flexural strength, and gloss were not much different from those obtained by using a typical process. Also, physical properties of the powders according to the present invention were the same as or better than those of Comparative Examples, and therefore, it was confirmed that a polymer latex powder may be effectively prepared by using a new preparation apparatus for coagulation of a polymer latex according to the present invention. [0090] According to the present invention, since a slurry having a higher solid content than that of a typical process may be prepared by using a new preparation apparatus for coagulation of a polymer latex and a use amount of water may be minimized in coagulation and aging processes of an emulsion polymerized polymer latex, energy costs may be reduced and an amount of generated wastewater may be decreased. In addition, since an amount of a coagulant used in the coagulation process may be reduced, cost reduction and quality improvement may be obtained. Also, there are effects of reducing logistics costs, such as packaging costs and transportation costs, due to a removal of fine particles of a polymer resin powder and an increase in apparent specific gravity. In addition, reduction of operational and investment costs may be obtained through simplification and efficiency of a process by developing an integrated process of coagulation and aging by simplifying typical coagulation and aging processes as well as coagulating with reduction of a long retention time of 30 minutes to 1 hour or more. [0091] The above-disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments, which fall within the true spirit and scope of the present invention. Thus, to the maximum extent allowed by law, the scope of the present invention is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description. WHAT IS CLAIMED IS: 1. An apparatus for preparing a polymer latex resin powder comprising: a latex tank; a coagulation bath; an aging bath; a dehydrator; and a dryer. wherein the apparatus for preparing a polymer latex resin powder has a structure including the coagulation and aging baths in an integrated-type reactor and the reactor has a ratio of length to diameter of 5 to 20. 2. The apparatus for preparing a polymer latex resin powder of claim 1, wherein one or more barrel pins are included in at least one surface of an upper or lower portion of inside of the reactor from outside of the integrated-type reactor including the coagulation and aging baths. 3. The apparatus for preparing a polymer latex resin powder of claim 1, wherein one or more internal stirrers are included in the integrated-type reactor including the coagulation and aging baths. 4. The apparatus for preparing a polymer latex resin powder of claim 1, wherein coagulation and aging of a polymer are substantially performed at the same time in the integrated-type reactor including the coagulation and aging baths. 5. The apparatus for preparing a polymer latex resin powder of claim 1, wherein the integrated-type reactor including the coagulation and aging baths comprises a polymer latex input line, a coagulant input line, and a steam input line. 6. A method of preparing a polymer latex resin powder using the preparation apparatus of claim 1 characterized in that coagulating and aging are not performed in two separate steps but performed at the same time in one reactor. 7. The method of claim 6, wherein a retention time of a polymer slurry in the coagulating and aging is in a range of 0.5 minutes to 30 minutes. 8. The method of claim 6, wherein a solid content of the polymer slurry is in a range of 25 wt% to 60 wt%. 9. The method of claim 6, wherein the coagulating is performed by adding 0.5 to 5 parts by weight of a coagulant based on 100 parts by weight of a polymer latex and direct steam. 10. The method of claim 6, wherein a solid content of the polymer latex is in a range of 10 wt% to 90 wt%. 11. The method of claim 6, wherein the polymer latex is a graft copolymer composed of a vinyl cyanide compound, a conjugated diene compound, and an aromatic vinyl compound. 12. The method of claim 6, wherein the polymer latex is selected from the group consisting of a styrene polymer latex, a butadiene polymer latex, a styrene-butadiene copolymer latex, an alkyl acrylate polymer latex, an alkyl methacrylate polymer latex, an alkyl acrylate-acrylonitrile copolymer latex, an acrylonitrile-butadiene copolymer latex, an acrylonitrile-butadiene-styrene copolymer latex, an acrylonitrile-alkyl acrylate-styrene copolymer latex, an alkyl methacrylate-butadiene-styrene copolymer latex, and an alkyl acrylate-alkyl methacrylate copolymer latex. 13. The method of claim 6, wherein a content of fine particles having an average particle diameter of 75 µm or less in the polymer latex resin powder is 1.5 wt% or less. 14. The method of claim 6, wherein a water content of the polymer latex resin powder is 30 wt% or less.

Full Text

FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; Rule 13)
TITLE
POLYMER-LATEX-RESIN-POWDER PRODUCING DEVICE, AND A METHOD FOR PRODUCING A POLYMER LATEX RESIN POWDER EMPLOYING THE SAME
APPLICANT
LG CHEM, LTD.
NATIONALITY: REBUBLIC OF KOREA
ofLG TWIN TOWERS
20, YEOUIDO-DONG,
YEONGDEUNGPO-GU SEOUL 150-721
REPUBLIC OF KOREA
The following specification particularly describes the nature of the invention and the manner in which is to be performed.

POLYMER-LATEX-RESIN-POWDER PRODUCING DEVICE, AND A METHOD FOR PRODUCING A POLYMER LATEX RESIN POWDER
EMPLOYING THE SAME
BACKGROUND
[0001] This application claims the priority of Korean Patent Application No.
10-2009-0072597 filed on August 7, 2009, which is hereby incorporated by reference in its entirety into this application.
[0002] The present invention disclosed herein relates to a new preparation
apparatus for coagulation of a polymer latex in the preparation of a polymer latex resin powder having a high solid content of an emulsion polymerized latex and a method of preparing a polymer latex resin powder using the same, and more particularly, coagulation and aging processes are substantially performed at the same time by changing a reactor structure so as to include coagulation and aging baths in an integrated reactor, and thus, a polymer latex resin powder having a high solid content may be prepared in a very short retention time in comparison to a typical process.
[0003] Coagulation of an emulsion polymerized polymer latex is performed
through breaking the stability of each latex particle stabilized by means of an emulsifier by a chemical method using various coagulants or a mechanical force with application of strong shear stress. The chemical method using coagulants breaks the stability by using different coagulant according to the type of a emulsifier used for securing the stability of a latex and the method of breaking the stability by using a mechanical force is performed in which a repulsive force between emulsifiers is

overcome by strong shear stress such that latex particles are agglomerated to each other.
[0004] Rapid coagulation was suggested as a method of preparing a polymer
latex as a powder in the emulsion polymerization process. This method allows a polymer in a latex to be agglomerated fast through breaking the stability of an emulsifier by introducing an excessive amount of an aqueous solution of a coagulant such as inorganic salt and acid. The agglomeration of polymer particles in the latex is denoted as coagulation, and the agglomerated polymer particles are denoted as a slurry. Since the agglomerated polymer particles are in a physically weak bond state, a phenomenon of easy break-up by means of external shear caused by a stirrer or the like may appear. Therefore, a primarily agglomerated slurry is heated to go through an aging process, a process of strengthening a bonding force by means of interpenetration between chains. The slurry thus formed undergoes dehydration and drying processes and a powder phase is finally obtained.
[0005] With respect to the foregoing rapid coagulation in which an excessive
amount of a coagulant is used, a process of agglomeration of polymer latex particles occurs very fast and in a disordered manner because the stability of the latex is broken very fast. Apparent specific gravity may decrease due to the foregoing disordered coagulation and a particle size distribution of final particles may become very broad.
[0006] In a typical polymer latex resin powder, small particles having an
average particle diameter of about 75 µm or less are denoted as "Fine" and large particles having an average particle diameter of about 1400 µm or more are denoted as "Coarse". The Fine may degrade the performances of dehydrator and dryer for a latex resin powder and may be a cause of generating many limitations in transfer and

packaging of the powder during a process because the Fine is easily scattered in the air. The Coarse may have limitations in transfer and storage and may have low compatibility with other polymer resins.
[0007] Meanwhile, FIG. 1 is a schematic diagram illustrating an apparatus
for a coagulation process of preparing a polymer latex resin powder according to the related art. The apparatus has a configuration including a latex storage tank 1, a coagulation bath 2, an aging bath 3, a dehydrator 4, and a dryer 5. [0008] . When a process of preparing a polymer latex resin powder is examined with reference to FIG. 1, a polymer latex stored in the latex storage tank 1 is first added to the coagulation bath 2 through a polymer latex input line 11 and then an aqueous solution of a coagulant, such as an inorganic salt or an acid, is added to the polymer latex through a coagulant input line 12 and water is added to the coagulation bath 2 through a water supply line 13 in order to adjust a solid concentration. The added coagulant aqueous solution breaks electrostatic stabilization by means of an emulsifier and a polymer slurry may then be obtained through a coagulation process that agglomerates polymer particles in the latex. The coagulated polymer slurry is transferred to the aging bath 3 and undergoes a process of aging by being maintained at a high temperature for 40 minutes to 90 minutes. The finally obtained slurry undergoes a dehydration process in the dehydrator 4 and is dried in the dryer 5, and a final polymer powder 15 is then obtained. Most of the added coagulant is dissolved in water in the dehydrator 4 and discharged 14 therefrom.
[0009] When the foregoing apparatus is used, a slurry having high viscosity
is not only difficult to be stirred during preparation of a slurry having a high solid content, but transfer is also impossible because a phenomenon of agglomeration is

accelerated due to a high temperature when the slurry is aged. Therefore, the-operation may be possible only under a low solid content because collection as a powder is very difficult.
[0010] A multi-stage continuous coagulation and aging process was
suggested in order to address the foregoing limitations. The process has advantages in that a polymer slurry having a low solid content may be effectively aged, but the process also may not be applied to a slurry having a high solid content and may be somewhat poor in terms of process efficiency because many stages must be passed through.
[0011] Accordingly, a slow coagulation process, which improves powder
characteristics of final particles generated by controlling a coagulation rate through a split input of a coagulant, was suggested as another method. Since coagulation occurs in a second well region having an energy barrier in the foregoing method, a coagulation rate is slow and there is room for completing redistribution of particles. Therefore, preparation of spherical particles by means of regular filling may be possible. However, an overall use amount of the coagulant is similar to that of the rapid coagulation and it is a method of performing coagulation by only using the split input. Therefore, generation of wastewater due to the excessive amount of the coagulant is inevitable and with respect to a first coagulation bath, since a small amount of the coagulant is introduced in comparison to that of the rapid coagulation, viscosity of the slurry increases. Thus, water must be added more in comparison to the rapid coagulation in order to secure flowability and a water content may be high in comparison to that of the rapid coagulation.
[0012] In all the foregoing methods, the flowability of the prepared polymer
latex slurry is affected by a solid content, a particle size distribution of the slurry, and

a contained water content. In particular, the flowability thereof is greatly affected by the solid content. When the solid content of the slurry is more than a certain amount, the slurry becomes agglomerated because the flowability of the slurry rapidly deteriorates, and as a result, the operation may be impossible. Therefore, a large amount of water may be further added during a coagulation process in order to improve the flowability of the slurry. The large amount of the added water increases energy costs generated for heating the slurry to a coagulation temperature and an aging temperature, and also increases post-processing costs by generating a large amount of wastewater during a dehydration process. Also, the efficiency thereof may decrease because direct steam is not used but energy is transferred to the slurry by condensing water as a medium.
[0013] As another method of collecting the powder from the emulsion
polymerized latex, a polymer latex powder is collected by using a gas-phase spray system. This is a method of collecting a polymer latex resin having a high solid content as a spherical powder by spraying the resin onto a surface with the flow of an excessive amount of a coagulant by using an atomizer. In this case, since the polymer latex maintaining a high solid content is in contact with the coagulant, rapid coagulation is completed at the moment of contact with the coagulant and thus, high apparent specific gravity may be obtained and the collection of a spherical powder required in a slow coagulation process may be possible. However, since an excessive amount of the coagulant must be used in order to prevent the generation of an unreacted latex, the generation of a large amount of wastewater is inevitable, and since a clogging phenomenon of the atomizer occurs frequently, the foregoing method is disadvantageous in terms of process stability.

[0014] Also, there has been much research controlling a particle size of the
powder under the existence of an organic solvent and improving apparent specific gravity, but in these cases, the foregoing powder characteristics may only be secured by using an excessive amount of the organic solvent.
[0015] As another method, there is shear coagulation, in which a slurry is
prepared by agglomeration between latex particles with application of shear stress caused by a strong mechanical force. A coagulant is not used but a polymer latex slurry is prepared by the application of shear stress caused by a high-speed rotation of 4000 rpm or more. However, with respect to the emulsion polymerized polymer latex having stability secured by using an emulsifier, the residual emulsifier remains in a collected powder and thus, may adversely affect thermal stability and color during processing.
SUMMARY
[0016] The present invention provides a method of preparing a polymer latex
powder having a high solid content as well as process characteristics being maintained in the preparation of a polymer latex powder with various methods by using a typical preparation apparatus for an emulsion polymerized polymer latex resin powder including a coagulation bath, an aging bath, a dehydration bath, and a dryer, in order to resolve various limitations of the related art.
[0017] The present invention is based on observations, in which a retention
time required for coagulation and aging is increased to about 30 minutes to 1 hour because typical coagulation and aging baths have separate and independent configurations and accordingly, various limitations are generated. According to the present invention, coagulation and aging processes may not only be substantially

performed in one reactor at the same time and in a very short retention time by using
a new preparation apparatus for coagulation of a polymer latex, in which both
coagulation and aging baths are included in an integrated-type reactor and one or
more barrel pins are attached to the integrated reactor, but excellent powder
characteristics may be secured by using a small amount of a coagulant and direct
steam. With respect to the foregoing polymer latex resin powder, various
characteristics, such as a high solid content, a low water content, a high apparent
specific gravity, and excellent processability, may be controlled to desired levels.
[0018] Embodiments of the present invention provide a new preparation
apparatus for coagulation of a polymer latex able to prepare a polymer latex resin powder having a desired high level of physical properties.
[0019] In other embodiments of the present invention, a method of preparing
of a polymer latex resin powder having a high solid content by using the new preparation apparatus for coagulation of a polymer latex is provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The accompanying drawings are included to provide a further
understanding of the present invention, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present invention and, together with the description, serve to explain principles of the present invention. In the drawings:
[0021] FIG. 1 is a schematic drawing illustrating a typical apparatus for a
coagulation process; and

[0022] FIG. 2 is a schematic drawing illustrating an integrated reactor of a
newly designed apparatus for preparing a polymer latex slurry according to the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0023] Preferred embodiments of the present invention will be described
below in more detail with reference to the accompanying drawings. The present
invention may. however, be embodied in different forms and should not be
constructed as limited to the embodiments set forth herein. Rather, these
embodiments are provided so that this disclosure will be thorough and complete, and
wiJJ fully convey the scope of the present invention to those skilled in the art.
[0024] An apparatus for preparing a polymer latex resin powder of the
present invention includes a latex tank, a coagulation bath, an aging bath, a
dehydrator, and a dryer, wherein the apparatus for preparing a polymer latex resin
powder has a structure including the coagulation and aging baths in an integrated-
type reactor and the reactor has a ratio of length to diameter of 5 to 20.
[0025] Also, a method of preparing a polymer latex resin powder of the
present invention is characterized in that coagulating and aging are not performed in two separate steps but performed at the same time in one reactor by using the new preparation apparatus for coagulation of a polymer latex.
[0026] Hereinafter, the present invention will be described in more detail
with reference to the accompanying drawings.
[0027] The present invention relates to a method of preparing a powder
having a low content of fine particles and improved apparent specific gravity through effective coagulation and aging of a slurry having a high solid content by using a

newly designed apparatus in which two steps, coagulation and aging processes, are reduced to one step.
[0028] FIG. 2 is a schematic drawing illustrating an integrated-type reactor
including both coagulation and aging baths in a newly designed apparatus for preparing a polymer latex slurry according to the present invention, in which the newly designed apparatus has a structure including the coagulation and aging baths in an integrated-type reactor 100 and the integrated-type reactor 100 has a ratio of length L to diameter D of 5 to 20.
[0029] Typically, the coagulation bath and the aging bath are included in
separate reactors and thus, a polymer slurry, which is coagulated by adding a coagulant and an appropriate amount of water to a polymer latex, is transferred to the aging bath to perform a process of aging at a predetermined temperature for a predetermined time.
[0030] However, in the present invention, coagulation and aging are
performed at the same time in the integrated-type reactor 100. In particular, a polymer latex is added to the reactor 100 through a polymer latex input line 110 and a small amount of a coagulant and direct steam are added thereto through a coagulant input line 120 and a steam input line 130, respectively.
[0031] In the integrated-type reactor 100 according to the present invention,
barrel pins inserted into the inside of the reactor are fixed at the outside thereof and one or more stirrers 150 rotate in the reactor. In particular, one or more barrel pins 140a and 140b are included in any one surface of an upper or lower portion of the inside of the reactor from the outside of the integrated-type reactor 100. Also, since the internal stirrers 150 continuously rotate in a polymer slurry, the polymer slurry in preparation may be induced to be broken up well without agglomeration while the

polymer slurry is in contact with the internal stirrers 150 and the barrel pins 140a and
140b. Shape of the barrel pin is not particularly limited and the barrel pins having
any shape, such as circle, triangle, taper, ellipse, diamond, or quadrangle, may be
used. Type of the stirrer 150 is not particularly limited and the stirrers having any
type, such as paddle, screw, twin-screw, or pin, may be used.
[0032] The apparatus of the present invention may adjust the viscosity of the
polymer slurry by the action of the barrel pins and the internal stirrers as well as the
structure of the integrated reactor, and a water content thereof may be adjusted by
using a mechanical force after the preparation of a slurry having high viscosity.
[0033] In the integrated-type reactor 100 having the foregoing structure, a
coagulation reaction occurs near positions where polymer latex, coagulant, and steam are introduced, and an aging reaction occurs in a rear portion of the reactor. Therefore, coagulation and aging may be substantially performed at the same time in the same reactor.
[0034] In particular, the integrated reactor 100 may have a ratio of length to
diameter of 5 to 20 in order to perform coagulation and aging at the same time and
the ratio having the foregoing range is desirable in terms of particle size control
through break-up. Also, since a use amount of water is minimized and direct steam
is used, heat may be effectively supplied by inducing condensation of the steam.
[0035] Meanwhile, a method of preparing a polymer latex resin powder of
the present invention having a high solid content by using the foregoing new preparation apparatus for coagulation of a polymer latex is characterized in that coagulating and aging are not performed in two separate steps but performed at the same time in one reactor.

[0036] A polymer latex used in the present invention is an emulsion
polymerized polymer latex having a solid content of 10 wt% to 90 wt% and may be a
graft copolymer composed of a vinyl cyanide compound, a conjugated diene
compound, and an aromatic vinyl compound. The graft copolymer is prepared by
polymerizing a mixture of an aromatic vinyl compound and a monomer of a vinyl
cyanide compound with a conjugated diene compound.
[0037] The conjugated diene compound is selected from the group consisting
of a butadiene rubber (BR), an ethylene-propylene-diene monomer rubber (EPDM),
a halobutyl rubber, a butyl rubber, styrene-isoprene-styrene (SIS), and a styrene-
butadiene rubber (SBR).
[0038] Also, the vinyl cyanide compound is selected from the group
consisting of acrylorritrile, methacrylonitrile, ethacrylonitrile, and a derivative thereof.
[0039] The aromatic vinyl compound is selected from the group consisting of
styrene, α-methylstyrene, α-ethylstyrene, para-methylstyrene, vinyl toluene, and a
derivative thereof.
[0040] A solid content of the graft copolymer is in a range of 25 wt% to 60
wt% and the solid content thereof may include 40 to 70 wt% of butadiene, 5 to 20
wt% of acrylonitrile, and 10 to 40 wt% of styrene.
[0041] The polymer latex of the present invention is not limited to the graft
copolymer composed of the vinyl cyanide compound, the conjugated diene
compound, and the aromatic vinyl compound, and other polymer latexes including an
emulsifier to maintain the stability thereof may be used.
[0042] Examples of the other polymer latexes including an emulsifier to
maintain the stability thereof may be a styrene polymer, a butadiene polymer, a
styrene-butadiene copolymer, an alkyl acrylate polymer, an alkyl methacrylate

polymer, an alkyl acrylate-acrylonitrile copolymer, an acrylonitrile-butadiene copolymer, an acrylonitrile-butadiene-styrene copolymer, an acrylonitrile-alkyl acrylate-styrene copolymer, an alkyl methacrylate-butadiene-styrene copolymer, an alkyl acrylate-alkyl methacrylate copolymer, etc.
[0043] Examples of the coagulant may be a water-soluble inorganic acid,
such as a sulfuric acid, a phosphoric acid, and a hydrochloric acid, or an inorganic salt such as a sulfate and a calcium salt. In general, the coagulant may be introduced more than a theoretical value required for coagulation and in the present invention, the coagulant is used in an amount range of 0.5 to 5.0 parts by weight based on 100 parts by weight of the polymer latex, may be used in an amount range of 0.5 to 3.0 parts by weight, and for example, may be used in an amount range of 0.5 to 2.0 parts by weight. That is, a polymer latex may be effectively coagulated by only a trace amount of the coagulant in the present invention.
[0044] The present invention prepares a polymer latex slurry through
coagulation by adding a coagulant and direct steam to the polymer latex, and when a solid content of the polymer latex used is higher than that of the polymer slurry to be prepared, a liquid phase of water may be selectively added in order to adjust the solid content. At this time, a content of the added water may be selected in a range of 5 to 500 parts by weight based on 100 parts by weight of the polymer latex in order to obtain an appropriate solid content.
[0045] Therefore, coagulation and aging are performed by adding the
polymer latex, a small amount of the coagulant the direct steam, and if necessary, the liquid phase of water into an integrated reactor as shown in FIG. 2. At this time, a coagulation and aging temperature may be in a range of 60°C to 100°C. In the integrated-type reactor having a structure of FIG. 2, a coagulation reaction occurs

near positions where polymer latex, coagulant, and steam are introduced, and an
aging reaction occurs in a rear portion of the reactor. Therefore, coagulation and
aging may be substantially performed at the same time in the same reactor.
[0046] Meanwhile, a retention time of the polymer slurry residing in the
integrated-type reactor is in a range of 0.5 minutes to 30 minutes, may be in a range
of 0.5 minutes to 10 minutes, and for example, may be in a range of 0.5 minutes to 5
minutes. Different from the case in which a long retention time of about 30 minutes
to 1 hour is needed when coagulation and aging processes are separately performed
by using a typical preparation apparatus as shown in FIG. 1, a slurry having excellent
powder characteristics may be prepared in a very short retention time by using a
newly designed apparatus in the present invention. The coagulation process is
substantially completed within a range of a few seconds to 1 minute during the
retention time, and aging is performed immediately after the coagulation process is
finished and continuously performed until the polymer slurry is discharged outside.
[0047] In the present invention, reaction may be performed in such a manner
that the retention time of the polymer slurry in the coagulation and aging processes exceeds 30 minutes, but the foregoing case is not economical because a size of the apparatus will be large.
[0048] A solid content of the polymer latex slurry of the present invention
prepared by using the foregoing process differs according to a solid content of the polymer latex, but the solid content of the polymer latex slurry may generally be in a range of 25 wt% to 60 wt%. When the solid content is less than 25 wt%, the retention time of the slurry may not be secured because the flowability of the slurry is too high, and when the solid content is more than 60 wt%, operation may be

impossible because the slurry blocks the inside of the apparatus due to a decrease in a feed force of the slurry.
[0049] The polymer slurry, in which the coagulation and the aging are
performed at the same time, is discharged from the integrated-type reactor and transferred to a slurry storage tank. The coagulated and aged slurry is collected as a powder through typical dehydration and drying processes.
[0050] Although aging at a high temperature is required for the
interpenetration between polymer chains in a typical process, a polymer slurry having a high solid content may be prepared by coagulation and aging processes in a short retention time in the present invention. High apparent specific gravity may be obtained with respect to the powder obtained through dehydration and drying because of the foregoing coagulation characteristics, and a content of fine particles may be very small. Also, since a slurry having high viscosity may be prepared according to selectively including a liquid phase of water, a water content may be adjusted by using a mechanical force of the stirrer and a powder having a low water content may be prepared.
[0051] The finally prepared polymer latex resin powder according to the
present invention may have a water content of 30 wt% or less and this may be desirable in terms of increasing apparent specific gravity.
[0052] Also, a content of fine particles having an average particle diameter of
75 um or less in the finally prepared polymer latex resin powder according to the present invention may be 1.5 wt% or less and this may be desirable in terms of minimizing a blow-off phenomenon during the collection of the powder and maximizing product recovery efficiency.

[0053] Hereinafter, examples are provided to allow for a clearer
understanding of the present invention, but the following examples are merely
presented to exemplify the present invention and the scope of the present invention is
not limited to the following examples.
[0054] Example 1
[0055] A graft copolymer composed of a vinyl cyanide compound, a
conjugated diene compound, and an aromatic vinyl compound of the present invention was an acrylonitrile (AN)-butadiene (BD)-styrene (SM) copolymer having a weight percentage ratio of AN : BD : SM of 13 : 60 : 27 and had a solid content of 44%.
[0056] The latex was introduced at a flow rate of 12 kg/hr into a new
integrated-type reactor as shown in FIG. 2 and a diluted sulfuric acid (H2SO4) was
used as a coagulant in an amount of 1.0 part by weight based on 100 parts by weight
of a total polymer content. While introducing direct steam, a liquid phase of water
was further mixed with a sulfuric acid corresponding to a solid content of a slurry
and then introduced to adjust the solid content of the polymer latex slurry to 30%.
[0057] A retention time in the newly designed integrated-type reactor was an
average of 1.5 minutes, and a coagulation and aging temperature was 75°C. An
aging process began immediately after a coagulation process finished and was
continuously performed until the slurry was discharged outside. The coagulated
slurry was discharged outside through newly designed stirrers and transferred to a
slurry storage tank. The coagulated and aged slurry was collected as a polymer resin
powder through dehydration and drying processes.
[0058] Example 2

[0059] A polymer resin powder was prepared in the same manner as Example
1 except that a solid content of a polymer latex slurry was 35%.
[0060] Example 3
[0061] A polymer resin powder was prepared in the same manner as Example
1 except that a solid content of a polymer latex slurry was 44%.
[0062] Example 4
[0063] A polymer resin powder was prepared in the same manner as Example
1 except that an input amount of a coagulant used was 0.7 parts by weight based on
100 parts by weight of a polymer latex.
[0064] Example 5
[0065] A polymer resin powder was prepared in the same manner as Example
1 except that an input amount of a coagulant used was 1.5 parts by weight based on
100 parts by weight of a polymer latex.
[0066] Comparative Example 1
[0067] An emulsion polymerized latex was prepared by using a typical
apparatus of FIG. 1. The same latex as that of Example 1 was introduced and a 10%
diluted sulfuric acid was used as a coagulant in an amount of 1.0 part by weight
based on 100 parts by weight of a total polymer content. A solid content of a total
slurry was adjusted to 27% by further adding water in order to maintain the
flowability of the slurry, and a retention time was 10 minutes and a coagulation
temperature was maintained at 75°C. The coagulated slurry was transferred to an
aging bath by means of an overflow method, a retention time in the aging bath was
60 minutes, and temperature thereof was maintained at 90°C. Subsequent processes
were the same as those of Example 1.
[0068] Comparative Example 2

[0069] An emulsion polymerized latex was prepared in the same manner as
Example 1 except that the coagulant in Comparative Example 1 is used in an amount
of 1.5 parts by weight based on 100 parts by weight of the polymer content.
[0070] Comparative Example 3
[0071] An emulsion polymerized latex was prepared in the same manner as
Example 1 except that the coagulant in Comparative Example 1 is used in an amount
of 2.0 parts by weight based on 100 parts by weight of the polymer content.
[0072] Water contents, apparent specific gravities, particle size distributions,
and whiteness values of the polymer iatex resin powders of Examples and
Comparative Examples were measured by using the following methods, and the
results thereof are presented in Table 1.
[0073] 1) Water content: Changes in weight were measured after completely
drying at 150°C by using a moisture meter (Merrier Toledo HR83-P).
[0074] 2) Apparent specific gravity: Measured in accordance with ASTM
D1985.
[0075] 3) Particle size distribution: Particle diameters were measured by
using standard sieves and contents of fine particles having a particle diameter of
75um or less and contents of coarse particles having a particle diameter of 1400 um
or more were measured.
[0076] 4) Whiteness of powders: L, a, and b values were measured by using a
colorimeter (Hunter Lab Co. Color Quest II). L. a, and b respectively denote values
of coordinate axes representing inherent colors. L may have a value from 0 to 100,
and L represents black as the value approaches 0 and white as the value approaches
100. a may be a positive or negative number with reference to 0, and a represents red
as the value is greater than 0 and green as the value is smaller than 0. b may be a

positive or negative number with reference to 0, and b represents yellow as the value
is greater than 0 and blue as the value is smaller than 0.
[0077] [Table 1]

Solid
content
(%) Coagulant (parts by weight) Water content (wt%) Apparent specific gravity (g/ml) Fine content (wt%) Coarse
content (wt%) Color

L a b
Example 1 30 1.0 26.10 0.32 0.7 16.3 96.37 0.16 2.35
Example 2 35 1.0 24.85 0.34 0.4 17.2 96.54 0.13 2.24
Example 3 44 1.0 21.23 0.37 0.3 18.4 96.81 0.10 2.13
Example 4 30 0.7 34.91 0.30 1.4 15.6 97.15 0.08 2.05
Example 5 30 1.5 22.97 0.33 0.9 24.2 96.31 0.16 2.47
Comparative Example 1 27 1.0 43.96 0.27 5.6 18.7 94.64 0.22 3.21
Comparative Example 2 27 1.5 34.59 0.28 4.1 23.7 94.77 0.22 3.65
Comparative
Example 3 27 2.0 25.92 0.30 2.5 27.1 94.72 0.16 4.01
[0078] As shown in Table 1, according to the results of Examples of the
present invention in which polymer latex slurries were prepared by using a new preparation apparatus for a polymer latex slurry, it may be confirmed that the slurry coagulated for having a higher solid content than that of Comparative Example 3 had a much lower water content, a content of fine particles was decreased, and whiteness was increased, when the same coagulant was used.
[0079] With respect to the coagulation of the slurry having a high solid
content, a content of fine particles significantly decreased as well as apparent specific gravity being increased. Accordingly, since post processing, such as transfer of the polymer latex resin powder and packaging of products, was facilitated and a blow-off

phenomenon of the fine particles disappeared, a working environment may be improved and productivity may be increased. Also, it may be understood that the higher the solid content was, the larger the apparent specific viscosity and the smaller the content of the fine particles were. In addition, since the added water was minimized, the generation of wastewater, an environmental problem, was reduced as well as an energy saving effects being obtained, and thus, post-processing costs may be reduced.
[0080] Also, when compared with the methods of Comparative Examples in
which powders were prepared through separate coagulation and aging processes typically requiring a time of 1 hour or more, the new coagulation process using a slurry having a high solid content may prepare a powder having physical properties equivalent to those of a typical powder by only using a short retention time of 5 minutes or less.
[0081] Further, in order to confirm physical properties of the polymer slurry
powders according to the present invention, 1 wt% of a lubricant and 0.5 wt% of an antioxidant were added to 26 wt% of the obtained acrylonitrile-butadiene-styrene copolymer dry powder and 74 wt% of styrene-acrylonitrile copolymer (LG Chemical. Ltd. 92HR) as a hard matrix and mixed. The mixture was prepared as pellet forms by using a 40 O extrusion kneader at a cylinder temperature of 220°C and physical property samples were prepared by injection molding the pellets. Physical properties were measured as below by using the samples and the results thereof are presented in the following Table 2.
[0082] 1) Izod impact strength (1/4" notched at 23°C, kg-cm/cm) - Measured
in accordance with ASTM D256.

[0083] 2) Izod impact strength (1/8" notched at 23°C, kg-cm/cm) - Measured
in accordance with ASTM D256.
[0084] 3) Tensile strength (50 mm/min, kg/cm ) - Measured in accordance
with ASTM D638.
[0085] 4) Gloss (45° angle) - Measured in accordance with ASTM D523.
[0086] 5) Flow index (220°C/10 kg, g/10 min) - Measured in accordance
with ASTM D123-8.
[0087] 6) Flexural strength (50 mm/min, kg/cm2) - Measured in accordance
with ASTM D790.
[0088] [Table 2]

Izod impact strength (1/4) Izod impact strength (1/8) Flow index Tensile strength Flexural
strength Gloss
Example 1 29.4 32.3 22.3 415 793 101.5
Example 2 29.7 32.8 22.1 413 794 101.8
Example 3 29.6 31.6 21.6 415 792 101.8
Example 4 29.1 32.1 22.1 416 791 101.4
Example 5 29.6 32.8 22.8 413 796 101.6
Comparative Example 1 28.4 28.6 22.1 414 793 101.9
Comparative Example 2 28.8 28.8 21.9 415 794 101.7
Comparative Example 3 29.0 29.2 21.6 418 794 101.4
[0089] As confirmed by the results of Table 2, when the results of physical
property measurements using the powder of Example 1 prepared according to the present invention were compared with those of Comparative Example 1, it may be confirmed that impact strength slightly increased even though the content of the

coagulant used was the same, and flow index, tensile strength, flexural strength, and
gloss were not much different from those obtained by using a typical process. Also,
physical properties of the powders according to the present invention were the same
as or better than those of Comparative Examples, and therefore, it was confirmed that
a polymer latex powder may be effectively prepared by using a new preparation
apparatus for coagulation of a polymer latex according to the present invention.
[0090] According to the present invention, since a slurry having a higher
solid content than that of a typical process may be prepared by using a new preparation apparatus for coagulation of a polymer latex and a use amount of water may be minimized in coagulation and aging processes of an emulsion polymerized polymer latex, energy costs may be reduced and an amount of generated wastewater may be decreased. In addition, since an amount of a coagulant used in the coagulation process may be reduced, cost reduction and quality improvement may be obtained. Also, there are effects of reducing logistics costs, such as packaging costs and transportation costs, due to a removal of fine particles of a polymer resin powder and an increase in apparent specific gravity. In addition, reduction of operational and investment costs may be obtained through simplification and efficiency of a process by developing an integrated process of coagulation and aging by simplifying typical coagulation and aging processes as well as coagulating with reduction of a long retention time of 30 minutes to 1 hour or more.
[0091] The above-disclosed subject matter is to be considered illustrative,
and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments, which fall within the true spirit and scope of the present invention. Thus, to the maximum extent allowed by law, the scope of the present invention is to be determined by the broadest

permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.

WHAT IS CLAIMED IS:
1. An apparatus for preparing a polymer latex resin powder comprising:
a latex tank;
a coagulation bath;
an aging bath;
a dehydrator; and
a dryer.
wherein the apparatus for preparing a polymer latex resin powder has a structure including the coagulation and aging baths in an integrated-type reactor and the reactor has a ratio of length to diameter of 5 to 20.
2. The apparatus for preparing a polymer latex resin powder of claim 1, wherein one or more barrel pins are included in at least one surface of an upper or lower portion of inside of the reactor from outside of the integrated-type reactor including the coagulation and aging baths.
3. The apparatus for preparing a polymer latex resin powder of claim 1, wherein one or more internal stirrers are included in the integrated-type reactor including the coagulation and aging baths.
4. The apparatus for preparing a polymer latex resin powder of claim 1, wherein coagulation and aging of a polymer are substantially performed at the same time in the integrated-type reactor including the coagulation and aging baths.

5. The apparatus for preparing a polymer latex resin powder of claim 1, wherein the integrated-type reactor including the coagulation and aging baths comprises a polymer latex input line, a coagulant input line, and a steam input line.
6. A method of preparing a polymer latex resin powder using the preparation apparatus of claim 1 characterized in that coagulating and aging are not performed in two separate steps but performed at the same time in one reactor.
7. The method of claim 6, wherein a retention time of a polymer slurry in the coagulating and aging is in a range of 0.5 minutes to 30 minutes.
8. The method of claim 6, wherein a solid content of the polymer slurry is in a range of 25 wt% to 60 wt%.
9. The method of claim 6, wherein the coagulating is performed by adding 0.5 to 5 parts by weight of a coagulant based on 100 parts by weight of a polymer latex and direct steam.
10. The method of claim 6, wherein a solid content of the polymer latex is in a range of 10 wt% to 90 wt%.
11. The method of claim 6, wherein the polymer latex is a graft copolymer composed of a vinyl cyanide compound, a conjugated diene compound, and an aromatic vinyl compound.

12. The method of claim 6, wherein the polymer latex is selected from the group consisting of a styrene polymer latex, a butadiene polymer latex, a styrene-butadiene copolymer latex, an alkyl acrylate polymer latex, an alkyl methacrylate polymer latex, an alkyl acrylate-acrylonitrile copolymer latex, an acrylonitrile-butadiene copolymer latex, an acrylonitrile-butadiene-styrene copolymer latex, an acrylonitrile-alkyl acrylate-styrene copolymer latex, an alkyl methacrylate-butadiene-styrene copolymer latex, and an alkyl acrylate-alkyl methacrylate copolymer latex.
13. The method of claim 6, wherein a content of fine particles having an average particle diameter of 75 µm or less in the polymer latex resin powder is 1.5 wt% or less.
14. The method of claim 6, wherein a water content of the polymer latex resin powder is 30 wt% or less.

Documents:

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Patent Number

279086

Indian Patent Application Number

361/MUMNP/2012

PG Journal Number

02/2017

Publication Date

13-Jan-2017

Grant Date

11-Jan-2017

Date of Filing

13-Feb-2012

Name of Patentee

LG CHEM, LTD.

Applicant Address

LG TWIN TOWERS 20 YEOUIDO-DONG, YEONGDEUNGPO-GU SEOUL 150-721 REPUBLIC OF KOREA

Inventors:

#	Inventor's Name	Inventor's Address
1	LEE, HYUNG SUB	3-1006, KUMHO APT. SOHO-DONG YEOSU-SI, JEOLLANAM-DO 555-713 REPUBLIC OF KOREA
2	KIM, CHANG SULL	2-605, LG CHEMINCAL DOWON SATAEK ANSAN-DONG YEOSU-SI, JEOLLANAM-DO 555-050 REPUBLIC OF KOREA
3	OH, HYUN TAEK	1-205, LG CHEMICAL DOWON SATAEK ANSAN-DONG YEOSU-SI, JEOLLANAM-DO 555-050 REPUBLIC OF KOREA
4	KIM, YONG	242-74, GUUI-DONG GWANGJIN-GU, SEOUL 143-200 REPUBLIC OF KOREA
5	PARK, EUN SEON	2-405, LG CHEMICAL ANSAN SATAEK 29, ANSAN-DONG, YEOSU-SI, JEOLLANAM-DO 555-050 REPUBLIC OF KOREA

PCT International Classification Number

B01J 2/00,B29B 9/02

PCT International Application Number

PCT/KR2010/004680

PCT International Filing date

2010-07-19

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	10-2009-0072597	2009-08-07	Republic of Korea