JP2653770B2 - Multilayer sheet for refrigerator interior with excellent gloss and chemical resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer sheet used in a refrigerator, and more particularly, to a refrigerator having a vacuum-molding process, wherein the refrigerator has a good internal gloss and a surface in contact with a heat insulating material. The present invention relates to a multilayer sheet for refrigerator interiors having excellent resistance to a foaming agent used for forming a heat insulating material in a refrigerator.

[0002]

2. Description of the Related Art Usually, a refrigerator case is constructed by assembling a steel sheet outside and a vacuum-formed interior molded article of a synthetic resin sheet inside the interior and then forming a liquid between the steel sheet and the interior molded article. Manufactured by injecting polyurethane and a foaming agent to form a polyurethane foam insulation.

[0003] Sheets for producing molded articles for interior use are made of various synthetic resins. European Patent Publication No. 0431
No. 166 A1 discloses a molded article for refrigerator interiors comprising a nitrile thermoplastic resin composition obtained by polymerizing a monomer mixture of a vinyl cyanide compound and an aromatic vinyl compound in the presence of a conjugated diene-based synthetic rubber.

Japanese Patent Application Laid-Open No. 5-42588 discloses a multilayer sheet for refrigerator interiors having a structure in which a styrene-based sheet and polybutylene terephthalate are laminated, wherein the polybutylene terephthalate layer has high resistance to Freon (trade name) gas. I have.

JP-A-6-293112 discloses a laminate sheet for refrigerator interiors comprising a polypropylene layer and a styrene-based resin layer, and bonding these two layers with an adhesive composed of hydrogenated styrene / conjugated diene copolymer. doing.

Further, European Patent Publication No. 053193 is disclosed.
No. 1 A2 discloses a method of forming a molded article for refrigerator interior by thermally deforming a sheet made of a styrenic polymer having a high syndiotactic shape.

[0007] The conventional molded article for refrigerator interior has the following problems.

First, the glossiness of molded articles for refrigerator interiors is poor. In particular, high impact polystyrene (HIPS) used as a raw material is a resin having no surface gloss. An ABS resin is generally superior in gloss surface to HIPS, but has a disadvantage that gloss is significantly reduced after vacuum forming. The molded product for the interior of the refrigerator should have high glossiness in view of aesthetics or the cleanness inside the refrigerator.

Second, the interior molding of the refrigerator, especially the layer in contact with the heat insulating material, should have high resistance to chemical substances such as foaming agents contained in the heat insulating material. C as a foaming agent
There are FC11, cyclopentane, HCFC141b, and the like, and these materials should maintain high resistance so as not to cause a crack or damage to an interior molded product.

Third, the molded articles for refrigerator interiors should be reusable in view of environmental pollution problems.

Accordingly, the present inventors have developed a multilayer sheet for refrigerator interiors that does not have the above-mentioned disadvantages and that satisfies the mechanical properties and workability as a molded product.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide a multilayer sheet for refrigerator interior which can maintain excellent gloss even after vacuum forming.

Another object of the present invention is to provide a multilayer sheet for refrigerator interiors having high resistance to a foaming agent contained in a heat insulating material of a refrigerator, such as CFC11, cyclopentane, and HCFC141b.

Still another object of the present invention is to provide a multilayer sheet for refrigerator interior in which a molded article for refrigerator interior can be reused.

[0015]

According to the multilayer sheet for refrigerator interior of the present invention, the inner layer of the sheet or the molded article is in contact with the heat insulating material of the refrigerator, and the outer layer is formed inside the refrigerator including the inside of the refrigerator door. The inner layer is made of an acrylonitrile / butadiene / styrene copolymer (hereinafter referred to as “ABS resin”), and the outer layer is preferably made of styrene having a thickness of 30 to 100 μm.
This is a laminate layer made of an acrylonitrile copolymer (hereinafter referred to as “SAN resin”). The ABS resin constituting the inner layer is an acrylonitrile / butadiene / styrene copolymer having a butadiene content of 10-2.
0% by weight and a weight average molecular weight of 150,000 to 3
The acrylonitrile content of the portion excluding butadiene is 20 to 45% by weight.

In the present invention, the weight-average molecular weight of the ABS resin refers to the SAN constituting the ABS resin matrix.
It means the weight average molecular weight of the resin.

Further, another multilayer sheet for refrigerator interior of the present invention comprises an inner layer, an outer layer, and an intermediate layer located between the inner layer and the outer layer in contact with the heat insulating material, wherein the inner layer is a modified ABS. The intermediate layer is made of ABS resin, and the outer layer is made of SAN resin. The modified AB
The S resin is an acrylonitrile / butadiene / styrene copolymer, the butadiene content of the modified ABS resin is 5 to 25% by weight, and the acrylonitrile content of the portion excluding butadiene is 35 to 45% by weight.

SAN as an outer layer of the multilayer sheet of the present invention
The resin has an acrylonitrile content of 20 to 30% by weight and a weight average molecular weight of 100,000 to 200,000.
It is.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The multilayer sheet for refrigerator interior according to the present invention has a structure comprising an inner layer and an outer layer or an inner layer, an intermediate layer and an outer layer.

In the present invention, the term "inner layer" refers to a layer in contact with a heat insulating material in a multilayer sheet for refrigerator interior or a molded product thereof, and the term "outer layer" forms the interior of the refrigerator including the interior of the door of the refrigerator. "Interlayer" means a layer located between the inner and outer layers.

The multilayer sheet of the present invention is manufactured by a co-extrusion method by extrusion molding without using an adhesive, in which an inner layer and an outer layer or an inner layer, an intermediate layer and an outer layer are used.

In a sheet comprising an inner layer and an outer layer,
The inner layer in contact with the heat insulating material is made of ABS resin, and the outer layer is preferably SAN having a thickness of 30 to 100 μm.
Made of resin.

The ABS resin constituting the inner layer is an acrylonitrile / butadiene / styrene copolymer, the butadiene rubber component is 10 to 20% by weight based on the ABS resin, and the weight average molecular weight is 150,000 to 300,000.
The acrolinitrile content of the portion excluding butadiene is desirably 20 to 45% by weight. here,
The acrylonitrile content means the acrylonitrile content of the acrylonitrile / butadiene / styrene copolymer excluding butadiene. If the weight average molecular weight of the ABS resin is less than 150,000, the thickness of the sheet tends to be uneven during vacuum forming, and if the weight average molecular weight exceeds 300,000, the compounding process and the extrusion process become poor. Cheap. The content of acrylonitrile functions as a factor for controlling the chemical resistance to a chemical such as a foaming agent, and is appropriately set depending on the type and properties (for example, solubility) of the foaming agent used.

The foaming agent used in the heat insulating material is, for example, CFC
In the case of a fluorochloro-substituted hydrocarbon such as 11 or a hydrocarbon compound such as cyclopentane, the content of acrylonitrile is desirably 20 to 35% by weight. When the blowing agent is a fluorochloro-substituted hydrocarbon such as HCFC141b, acrylonitrile is used. Content is 35-45% by weight
Is desirable. When a foaming agent having high solubility in ABS resin such as HCFC141b is used, if the content of acrylonitrile is less than 35% by weight, the molded article for interior may be sharpened by HCFC141b.
When the acrylonitrile content exceeds 45% by weight, no sharpness occurs, but the workability is poor and discoloration tends to occur during the processing. When the content of the butadiene rubber component constituting the ABS resin is less than 10% by weight, the impact strength is insufficient, and when the content exceeds 20% by weight, rigidity is insufficient.

The SAN resin forming the outer layer is 30 to 10
It is desirable to have a thickness of 0 μm. Its thickness is 10
When the thickness exceeds 0 μm, the impact strength of the sheet is reduced and the sheet is unsuitable for refrigerator interior. When the thickness is less than 30 μm, it is difficult to have excellent gloss. S forming the outer layer
It is desirable that the AN resin has excellent gloss and transparency, and has a small difference in viscosity from the ABS resin. SAN resin and A
This is because if the difference in viscosity from the BS resin is large, the lamination process is difficult to perform smoothly. To meet these requirements, the acrylonitrile content of the SAN resin is in the range of 20-30% by weight and its weight average molecular weight is 100,00.
It should be in the range of 0-200,000.

Further, another multilayer sheet for refrigerator interior according to the present invention comprises an inner layer in contact with a heat insulating material, an outer layer and an intermediate layer located therebetween, wherein the inner layer is made of a modified ABS resin, and the intermediate layer is The outer layer is made of an ABS resin, and the outer layer is made of a SAN resin.

One embodiment of the present invention, comprising an inner layer, an intermediate layer and an outer layer, has been developed to be particularly resistant to HCFC141b. Foaming agent HCFC
The modified ABS resin forming the inner layer in contact with 141b is an acrylonitrile / butadiene / styrene copolymer,
The butadiene rubber component is 5 to 25 with respect to the modified ABS resin.
% By weight, and the acrylonitrile content of the portion excluding butadiene is 35 to 45% by weight. When the content of acrylonitrile is less than 35% by weight, the molded article after the production of the refrigerator is not easily resistant to HCFC141b, so that the molded article is apt to crack or deform. When the content exceeds 45% by weight, the ABS resin forming the intermediate layer is used. Peeling phenomenon occurs due to insufficient adhesive strength. When the butadiene rubber content in the modified ABS resin is less than 5% by weight, the sheet tends to be crushed at the time of vacuum forming, and when the rubber content exceeds 25% by weight, the viscosity is high and mechanical problems occur in the extrusion process.

ABS resin forming the intermediate layer and S forming the outer layer
The AN resin is the same as the ABS resin and the SAN resin in the sheet having the above-described two-layer structure of the inner layer and the outer layer. However, in a sheet having a three-layer structure consisting of an inner layer / intermediate layer / external layer, a recycled ABS resin can be used for the intermediate layer. The two-layer or three-layer sheet according to the present invention can be reused because it is manufactured by a lamination process without using an adhesive.

The sheet of the present invention comprising an inner layer / intermediate layer / outer layer preferably has an inner layer thickness of 0.1 to 1.0.
mm, the thickness of the intermediate layer is 1.0 to 5.0 mm, and the thickness of the outer layer is 30 to 100 μm. Modified AB
If the thickness of the inner layer made of S resin is less than 0.1 mm, stretching occurs during the vacuum forming process and the thickness becomes 300 μm or less, so that HCFC141b used as a foaming agent penetrates through the modified ABS layer and enters inside. There is also a possibility that the intermediate layer is exposed due to permeation or surface defect.

The multilayer structure for refrigerator interior having a two-layer structure or a three-layer structure according to the present invention maintains excellent gloss after vacuum forming, has high resistance to blowing agents such as CFC11, cyclopentane and HCFC141b, and is a molded article. Can be reused.

[0031]

Next, the present invention will be described more specifically with reference to the following examples. The following examples are merely illustrative of the present invention and do not limit the scope of the present invention.

Example 1 Example 1 is an example of a sheet having a two-layer structure of an inner layer and an outer layer according to the present invention, and Comparative Example 1 is an example for comparison with Example 1.

An ABS resin is charged into a main extruder having a screw diameter of 65 mm into a sheet extruder provided with a feed block capable of extruding a sheet having a two-layer structure, and a sub-extruder having a screw diameter of 45 mm is provided. The SAN extruder is charged with the average temperature of the main extruder at 210 ° C., the average temperature of the sub-extruder at 205 ° C., the screw speed of the main extruder at 80 rpm, and the screw speed of the sub-extruder. At 20 rpm to laminate the sheet. The ABS resin for forming the inner layer has an acrylonitrile content of 27% by weight, a weight average molecular weight of 200,000, and a butadiene rubber content of 13% by weight except for butadiene.
Met. The SAN resin for forming the outer layer had an acrylonitrile content of 27% by weight and a weight average molecular weight of 150,000.

The overall thickness of the laminated sheet was 3.0 mm, and the thickness of the outer layer formed of SAN resin was 50 μm. The gloss of this sheet is 99, which is ASTM D2457 (incident angle 60
Degree).

After vacuum forming the sheet, the glossiness was measured by the above method. The result was 98, and there was almost no change in glossiness after vacuum forming. According to ASTM D3029, the impact strength (F
DI: Falling Dart Impact) 2900N
Met.

(Comparative Example 1) The operation of the sub-extruder was stopped and a sheet consisting of a single layer of 3.0 mm thick ABS resin was produced in the same manner as in Example 1 using only the main extruder to obtain a sheet. The gloss of the sheet was measured. The glossiness of the sheet was 96, and the glossiness after vacuum forming was 92. Therefore, in Comparative Example 1, it was found that the glossiness after vacuum forming was significantly lower than the glossiness before vacuum forming.

(Example 2) Examples 2 to 4 are examples of a sheet having a three-layer structure of an inner layer / intermediate layer / outer layer according to the present invention. Comparative Examples 2 to 4 are sheets of Examples 2 to 4. This is an example for comparison.

A sheet extruder capable of extruding a three-layered sheet, an ABS extruder having a screw diameter of 65 mm is used.
The modified ABS resin was introduced into the first sub-extruder having a screw diameter of 45 mm, and the screw diameter was 40 mm.
The second extruder of 2 mm was charged with SAN resin, and the average temperatures of the main extruder, the first sub-extruder and the second sub-extruder were set to 210 ° C., 220 ° C. and 205 ° C., respectively. The sheet was laminated and formed with the first sub-extruder and the second sub-extruder at screw rotation speeds of 80, 40 and 20 rpm, respectively. The modified ABS resin for forming the inner layer has an acrylonitrile content of 40 parts except for butadiene.
% By weight, the weight average molecular weight was 110,000, and the butadiene rubber content was 10% by weight. The ABS resin for forming the intermediate layer has an acrylonitrile content of 27% by weight and a weight average molecular weight of 18% excluding butadiene.
000, butadiene rubber content was 13% by weight. The SAN resin for forming the outer layer has an acrylonitrile content of 27% by weight and a weight average molecular weight of 12,000.
It was 0.

The thickness of the laminated sheet is 0.5 mm for the inner layer, 2.5 mm for the intermediate layer, and 50 μm for the outer layer.
m. The glossiness of this sheet was 99. At this time, HCFC141b was used as a foaming agent, and the produced refrigerator was subjected to a temperature change from −30 ° C. to 60 ° C. for 2 hours, 60 ° C. for 4 hours, and 60 ° C. to −30 ° C. As a result of observing the appearance of the molded article such as cracks and deformation through a four-cycle cooling / heating test in which the temperature was changed for 2 hours, no abnormalities were found. The yellowness of the molded article measured by JIS K7103 was 0.1.

(Example 3) The acrylonitrile content excluding butadiene was 35% by weight, and the weight average molecular weight was 1
A sheet was formed in the same manner as in Example 2 except that a modified ABS resin having a 20,000 butadiene rubber content of 10% by weight was used, and a similar test was performed. As a result, there was no abnormality in the thermal cycle test,
The glossiness was 99 and the yellowness was 0.2.

(Example 4) In place of the ABS resin forming the intermediate layer, the molded product produced in Example 2 was crushed into AB.
A sheet was formed in the same manner as in Example 2 except that 15% by weight of the S resin was mixed with an ABS resin (main extruder) to form an intermediate layer, and a similar test was performed. As a result, there was no abnormality in the cooling / heating cycle test, and the glossiness was 99 and the yellowness was 0.2.

Comparative Example 2 An acrylonitrile content of 32
A sheet was formed and tested in the same manner as in Example 2, except that a modified ABS resin having a weight% of 130,000 and a butadiene rubber content of 10% by weight was used. As a result, in the cooling / heating cycle test, a glow was generated, and the glossiness was 99 and the yellowness was 0.1.

Comparative Example 3 A method similar to that of Example 2 except that the operation of the first sub-extruder and the second sub-extruder was stopped in Example 2, and a single-layer sheet of 3.0 mm was produced. To form a sheet, and a test was conducted. As a result, in the cooling / heating cycle test, a sharpness was generated, and the glossiness was 96 and the yellowness was 0.2.

Comparative Example 4 A sheet was prepared in the same manner as in Comparative Example 3 except that the modified ABS resin was used instead of the ABS resin and the cylinder average temperature of the main extruder was set to 220 ° C. Formed and tested. As a result, in the cooling / heating cycle test, no sharpness occurred, and the glossiness was 95 and the yellowness was 1.3.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location F25D 23/06 F25D 23/06 T // B29C 47/06 B29C 47/06 51/14 51/14 B29K 55:02 (72) Inventor Kim Tae Wook Republic of Korea Gyeonggi-do Gumpo Dangdong Dusan apartment 101-205 (56) References JP-A-2-284906 (JP, A) JP-A-6-313091 (JP, A) JP-A-6-293112 (JP, A) JP-A-5-42588 (JP, A)

Claims (9)

(57) [Claims] 1. A butadiene rubber content of 10 to 20% by weight
Having a weight average molecular weight of 150,000 to 300,0
An inner layer of an acrylonitrile / butadiene / styrene copolymer (ABS resin ) having an acrylonitrile content of 20 to 45% by weight excluding butadiene, and an acrylonitrile content of 20 to 30% by weight. A multilayer sheet for refrigerator interiors comprising an outer layer made of a styrene / acrylonitrile copolymer having an average molecular weight of 100,000 to 200,000 and manufactured by a laminating process. 2. The foaming agent used for the heat insulating material of the refrigerator is CF.
In the case of C11 or cyclopentane, the ABSresin
Means that the acrylonitrile content of the part excluding butadiene
2. The composition according to claim 1, wherein the content is 20 to 35% by weight.
Refrigerator interior sheet. 3. The foaming agent used for the heat insulating material of the refrigerator is HC.
In the case of FC141b, the ABS resin has an acrylonitrile content of 35 to 45% by weight excluding butadiene.
The multilayer sheet for refrigerator interior according to claim 1, wherein: 4. Any of Claims 1 to 3 the thickness of the outer layer is characterized in that it is a 30~100μm
Multilayer sheet for refrigerator interior according to any. 5. An inner layer comprising an acrylonitrile / butadiene / styrene modified copolymer having a butadiene rubber content of 5 to 25% by weight and an acrylonitonyl content excluding butadiene of 35 to 45% by weight, and a butadiene rubber. The content is 10 to 20% by weight, the weight average molecular weight is 150,000 to 300,000, and the acrylonitrile content excluding butadiene is 20 to 20%.
An intermediate layer composed of an acrylonitrile / butadiene / styrene copolymer having a weight percentage of 45% by weight and a styrene / acrylonitrile copolymer having an acrylonitrile content of 20 to 30% by weight and a weight average molecular weight of 100,000 to 200,000; A multilayer sheet for refrigerator interior, which is made up of an outer layer and manufactured by a laminating process. 6. The thickness of the inner layer is 0.1 to 1.0 mm.
The multilayer sheet for refrigerator interior according to claim 5, wherein: 7. The intermediate layer has a thickness of 1.0 to 5.0 mm.
The multilayer sheet for refrigerator interior according to claim 5 or 6, wherein: 8. The multilayer sheet for refrigerator interior according to claim 5, wherein the thickness of the outer layer is 30 to 100 μm. 9. The intermediate layer according to claim 1 , wherein
The multilayer sheet for refrigerator interior according to claim 5, comprising a recycled ABS resin recycled from the molded article for refrigerator interior manufactured by the multilayer sheet according to any one of the above.