Title of Invention	PVC COMPOSITIONS FOR DOOR GASKET OF REFRIGERATOR
Abstract	PVC compositions for door gasket of a refrigerator comprising 0.01 to 1.0 parts by weight of at least one biocide selected from a group consisting of methyl-2-benzimidazol carbamate, 2-(4-triazolyl)- benzimidazol, O-[2-(4-chlorophenyl)-ethyl]-O-(1,1-dimethylethyl)-1H-1, 2, 4-triazol-1-ethanol, and zinc bis(2-pyridylthio-1-oxide) based on 100 parts by weight of PVC.

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BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyvinyl chloride (PVC) compositions for door gasket of a refrigerator and a method for manufacturing a door gasket of a refrigerator using the compositions and particularly, to PVC compositions for door gasket of a refrigerator and a method for manufacturing a door gasket of a refrigerator using the compositions which prohibit formation of molds or bacteria due to migration of plasticizer by adding a certain biocide to the PVC compositions. 2. Description of the Background Art The conventional PVC compositions for door gasket of a refrigerator comprises PVC, plasticizer, heat-resistant, cold-resistant and weather-resistant stabilizers, filler and pigment. A gasket is manufactured by mixing, compounding and extruding. Since the PVC has a form of powder, a plasticizer is used to smoothen the PVC thus to facilitate the manufacturing process. However, a PVC door gasket for a refrigerant manufactured by the above- mentioned process has a migration phenomenon which causes the plasticizer to be leak off the gasket at 60 to 80°C. Also, at a high temperature higher than 100 °c, more than 1 to 2% of plasticizer in a total weight of the PVC gasket comes out. Therefore, portions of contact surfaces with ABS or HIPS which are materials for inner surface of a refrigerator are easily contaminated and there is a problem that the portion is discoloured to yellow, blue dot or red color since there are sufficient spaces on the surface of the gasket where molds and bacteria can propogate. In order to prohibit propagation of bacteria, a mold preventive in which 10, 10"-oxybisphenoxagene (product name of Hokustar-HP of the Gitagooga furnitures of Japan) is added is disclosed in Korean Patent laid-open No. 10- 1993-023682 and Publication No. 10-1995-006264 but the effect was not sufficient. SUMMARY OF THE INVENTION Therefore, it is, an object of the present invention to provide PVC compositions for door gasket of a refrigerator and a method for manufacturing a door gasket of a refrigerator using the compositions which prohibit contamination and discoloration due to propagation of molds or bacteria on the surface of a gasket by adding a certain biocide to PVC. To achieve these and other advantages and in accordance with the purpose of the present invention as embodied and broadly described herein, there is provided a polyvinyl chloride composition for door gasket of a refrigerator comprising 0.01 to 1.0 parts by weight of methyl-2-benzimidazol carbamate, 2- (4-thiazolyl)-benzimidazol, a-[2-(4-chlorophenyl)-ethyl]- a-(1,1-dimethylethyl)-1 H- 1,2,4-triazol-1-ethanol and zinc bis(2-pyridylthio-1-oxide) based on 100 parts by weight of polyvinyl chloride. The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention. According to the present invention, a polyvinyl chloride having a degree of polymerization of about 1300 may be used. Biocides used in the present invention prohibit contamination and discoloration by molds or bacteria occurred by migration of a plasticizer. Following biocides are used in the present invention. Methyl-2-benzimidazol carbamate (general name: carbendazim) C [T^N^>—nhccoch3 2-(4-triazolyl)-benzimidazol (general name: TBZ) a- [2-(4-chlorophenyl)-ethyl]- a-(1,1-dimethylethyl)- 1H-l,2,4-triazol-1-ethanol (general name: tebukonazol) Zinc bis (2-pyridylthio-1 -oxide) (general name : zinc-pyrithion) As a biocide, a single chemical compound can be used and two or more kinds of biocides can be mixed to use. The biocide according to the present invention can obtain more preferable efficiency mixing two or more chemical compounds. The amount of the biocide in use is 0.01 to 1.0 parts by weight based on 100 parts by weight of PVC. If the amount of biocide is smaller than 0.01 parts by weight, the effect of the biocide is not remarkable and if larger than 1 parts by weight, further effect cannot be obtained. In the PVC composition in accordance with the present invention, other general additives may be added. Plasticizer may be added to make the process of extraction, compressed transformation easier by causing a plastic flow giving fluidity to PVC macromolecule and to increase flexibility by decreasing hardness of the polymer. A As a plasticizer, dioctyl phthalate (DOP), dioctyl adiphate (DOA), diisodecyi phthalate (DIP) and trioctyl trimelitate (TOTM) are used and generally, 30 to 80 parts by weight or preferably, 50 to 70 parts by weight of plasticizer is used based on 100 parts by weight of PVC. Also, a stabilizer may be added to stabilize the polymer to heat, oxygen and ultraviolet rays in processing progress or in use. Stabilizer includes a heat- resistant stabilizer such as barium stearate, calcium stearate and epoxyed bean oil, a cold-resistant stabilizer such as butyltin laurate complex and a weather- resistant stabilizer such as organic phosphite ester-based complex. 1 to 5 parts by weight of stabilizer is used based on 100 parts by weight of PVC. Filler may be added to improve mechanical intensity, size stability, heat transformation temperature, hardness and other physical characteristics. As a filler of the present invention, CaCO3 is preferably used and added in the amount of 5 to 50 parts by weight and preferably, 10 to 30 parts by weight based on 100 parts by weight of PVC. Also, pigment may be added to obtain a favorable color and added in the amount of 0.001 to 1 parts by weight based on 100 parts by weight of PVC. For example, the pigment include titanium oxide, carbon black or violet. In one illustration to manufacture the PVC of the present invention, conventionally, a Henschal mixer may be used. PVC, the alternative additives and pigments as described above are added in the mixture, maintaining the temperature of the mixer in the range of 60 to 120°C, and stirred at a low speed of 400rpm for 1 to 2 minutes. Plasticizer is introduced into the mixture at the temperature of 50 to 100°C and stirred at low speed or alternately at low and high speed, and preferably at low speed. Then, filler is added and formulated at the temperature of 105 to 110°C. The formulation is discharged and transferred into a cooling mixer. The formulation is treated by cooling to lower than 40°C and a resultant product in the form of powder is obtained. The powder products are transferred to an extruder and extruded. Hereinafter, the present invention will be described with reference to Examples. Examples 1 to 6 Temperature of an oil jacket of a 200L Henschal mixer was maintained at 80°C and PVC having 1300 of polymerization degree and the other additives were introduced into the mixer as defined in table 1. The PVC mixture was stirred at a low speed of 400 rpm for 2 min. In Table 1, BP-203S is a commercial product comprising Barium stearate (Songwon Industrial Co. Ltd. in Pusan, Korea) and BZ-108 is a commercial product comprising Calcium stearate (Songwon Industrial Co. Ltd. in Pusan, Korea), which are heat- resistant stabilizers. Then, 1 kg. of plasticizer per one minute was added through a plasticizer heat riser and stirred at a speed of 500 rpm. Calcium carbonate (CaCO3) based filler is added to the above resultant mixure, formulated at 110°C. The formulation was discharged at 125°C and transferred to a cooling mixer. Then the resultant formulation was treated by cooling to lower than 40°C and the product was obtained in the form of powder. The powder-type products were extruded to manufacture a gasket. The result of a characteristic measurement of the products obtained from the above Examples is described in Table 2. resistance test against bacteria : name of colon bacilli E-Coli (ATCC 25922) resistance test against mold : ASRM G-21 As apparent from the result of the Examples, a PVC composition of the present invention has an excellent characteristic to be used for a door gasket of a refrigerator and particularly, there is an advantage that the compositions are efficient to prohibit transformation and discoloration of the gasket by prohibiting propagation of molds and bacteria due to migration of plasticizer. As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the meets and bounds of the claims, or equivalence of such meets and bounds are therefore intended to be embraced by the appended claims. WE CLAIM : 1. A polyvinyl chloride composition for door gasket of a refrigerator comprising 0.01 to 1.0 parts by weight of methyl-2-benzimidazol carbamate, 2- (4-thiazolyl)-benzimidazol, a-[2-(4-chlorophenyl)-ethyl]- a-(1,1-dimethylethyl)-1 H- 1,2,4-triazo-1-ethanol and zinc bis(2-pyridylthio-1 -oxide) based on 100 parts by weight of polyvinylchloride. 2. The composition as claimed in claim 1 comprising 30 to 80 parts by weight of a plasticizer, 1 to 5 parts by weight of a stabilizer, 5 to 50 parts by weight of a filler and 0.001 to 1 parts by weight of pigment based on 100 parts by weight of polyvinyl chloride. 3. A method for manufacturing a door gasket of a refrigerator comprising the steps of mixing 0.01 to 1.0 parts by weight of methyl-2-benzimidazol carbamate, 2-(4-thiazolyl)-benzimidazol, a-[2-(4-chlorophenyl)-ethyl]- a-(1,1-dimethylethyl)- 1H-1,2,4-triazol-1-ethanol and zinc bis(2-pyridylthio-1 -oxide), 30 to 80 parts by weight of a plasticizer, 1 to 5 parts by weight of a stabilizer, 5 to 50 parts by weight of a filler and 0.001 to 1 parts by weight of a pigment based on 100 parts by weight of polyvinyl chloride at the temperature of 50 to 120°C in a mixer ; discharging and cooling the mixture at a temperature lower than 40°C in a cooling mixer to produce a pulverized formulation ; and extruding the pulverized formulation in an extruder. 4. A polyvinyl chloride composition for door gasket of a refrigerator, substantially as herein described, particularly with reference to the examples. PVC compositions for door gasket of a refrigerator comprising 0.01 to 1.0 parts by weight of at least one biocide selected from a group consisting of methyl-2-benzimidazol carbamate, 2-(4-triazolyl)- benzimidazol, Ó-[2-(4-chlorophenyl)- ethyl]- Ó-(1,1-dimethylethyl)- 1H-1, 2, 4-triazol-l-ethanol, and zinc bis(2-pyridylthio-l-oxide) based on 100 parts by weight of PVC.

Documents:

00530-cal-2001-abstract.pdf

00530-cal-2001-claims.pdf

00530-cal-2001-correspondence.pdf

00530-cal-2001-description (complete).pdf

00530-cal-2001-form 1.pdf

00530-cal-2001-form 13.pdf

00530-cal-2001-form 18.pdf

00530-cal-2001-form 2.pdf

00530-cal-2001-form 3.pdf

00530-cal-2001-form 5.pdf

00530-cal-2001-letter patent.pdf

00530-cal-2001-priority document others.pdf

00530-cal-2001-reply f.e.r.pdf