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.
Full Text 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


Patent Number 211062
Indian Patent Application Number 530/CAL/2001
PG Journal Number 42/2007
Publication Date 19-Oct-2007
Grant Date 16-Oct-2007
Date of Filing 18-Sep-2001
Name of Patentee LG ELECTRONICS INC.
Applicant Address 20, YOIDO-DONG YONGDUNGPO-KU, SEOUL
Inventors:
# Inventor's Name Inventor's Address
1 KIM HYUN KYO LUCKY APT. 8-1320, JURYE 3-DONG, SASANG-KU BUSAN
PCT International Classification Number C 08 K 3/00,5/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 28922/2001 2001-05-25 Republic of Korea