DE19528419A1 - Multi-layer fabric for an inner casing of a chiller - Google Patents

Abstract

The multi-layer sheet for an internal box of a refrigerator, which is prepared by a co-extrusion process, comprises an inner layer of an acrylonitrile/butadiene/styrene(ABS) copolymer having a weight-average molecular weight of 150,000 SIMILAR 300,000, which contains 10 SIMILAR 20% by weight of a butadiene rubber as per the ABS copolymer and 20 SIMILAR 45 % by weight of an acrylonitrile as per the matrix of styrene/acrylonitrile; and an outer layer of a styrene/acrylonitrile(SAN) copolymer having a weight-average molecular weight of 100,000 SIMILAR 200,000, which contains 20 SIMILAR 30 % by weight of an acrylonitrile. The multi-layer sheet of this invention may comprise a further inner layer of a modified ABS copolymer containing 5 SIMILAR 25 % by weight of a butadiene rubber as per the ABS resin and 35 SIMILAR 45 % by weight of an acrylonitrile as per the matrix of styrene/acrylonitrile.

Description

The invention is concerned with multi-layer sheets for an inner housing of a refrigerator, such as a refrigerator or the like, which are made from synthetic resins. In particular, the invention is concerned with multilayer fabrics for forming an inner housing of a Kältema machine by means of a vacuum molding process, which are produced by coextrusion of synthetic resins. The inner housing of a refrigerator according to the invention has an excellent glossy external appearance and stress cracking resistance to a foaming agent, such as CFC-11 (trichloromonofluoromethane), cyclopentane or HCFC 141b (1.1-di chloro-1-fluoroethane
The term "an inner housing of a refrigerator" includes the inside of a door of a refrigerator or a refrigerator or the like.

The housing of a refrigerator or refrigerator is manufactured in that an inner housing and an outer housing be composed, with a space between the two Ge houses is filled with a rigid polyurethane foam, which is formed by the fact that a liquid polyurethane and a foaming agent can be injected. In general it is Outer housing made of sheet steel, and the inner The housing is made of a flat material made of hard materials Vacuum molding process manufactured. The rigid polyurethane foam has the function of a heat insulator, which is thereby formed is that a liquid polyurethane and a foaming agent be injected.  

As a foaming agent, CFC-11 is often used for thermal insulation foam from refrigerators or refrigerators, is replaced by HCFC 141b nowadays because CFC-11 is used for Destruction of the ozone layer in the stratosphere contributes.

Numerous fabrics for the inner casing and process Ways of making the same have been proposed.

EP 431 166 A1 describes an inner housing of a refrigerator or described a refrigerator, which with a thermoplastic resin composition which (a) has a high thermoplastic nitrile resin composition, which a Graft copolymer obtained by polymerization is in the presence of a corresponding synthetic chew Tschuks based on diene, a monomer mixture from a vinylzya nid compound and an aromatic vinyl compound, and / or (b) a thermoplastic high nitrile resin composition tongue, which is a mixture of a graft copolymer with a Vinyl cyanide compound / aromatic vinyl compound copo has lymer.

In Japanese Patent Application Laid-Open No. 5-42588 described a lamination sheet for an inner case ben, which by means of a styrene polymer or styrene polymer and a polybutylene terephthalate is laminated. For this one message it is known that the layer of polybutylene terephthalate lat resistant to fluorinated / chlorinated hydrocarbons is fabric.

Japanese Patent Application Laid-Open No. 6-293112 is described a sheet for an inner housing, which comprises two layers. One layer is a propylene layer and the other is a styrene polymer layer, and both layers are connected to each other by means of a connecting material, wel ches a hydrogenated styrene / corresponding diene copolymer contains.  

In addition, EP 531 931 A2 describes a laminate which at least one surface layer made of a styrene polymer which is highly syndiotactic in configuration and has at least one different layer than the surfaces Has layer of a thermoplastic resin.

The flat structures for the inner housing of a refrigerator or a refrigerator should have good physical properties, such as Stiffness and impact resistance, easy formability, one excellent gloss and resistance to stress cracking over a foaming agent. Furthermore, with regard to Environmental problems the inner case is recycled and simple Way can be reused.

The inner housing, which is made of highly impact-resistant polystyrene (HIPS) manufactured, can not have an excellent gloss, whether it has good properties in terms of stiffness that Formability and stress crack resistance. In general NEN has excellent acrylonitrile / butadiene / styrene (ABS) resin shiny outer appearance, but there is Tends to have the excellent glossy appearance image disappears after vacuum forming.

The molded inner case of a refrigerator and the one made of waste Resin obtained should be at the time of molding be recycled and reused without environmental pro surrender.

With conventional flat structures for the inner housing, this difficulty due to poor compatibility of the Do not easily dissolve polymers in the resin composition. At for example, the inner case can be Japanese Disclosure No. 6-293112 do not recycle because Polypro pylene and styrene are not compatible. Of course it is important tig that the inner housing against a foaming agent, such as CFC 11, cyclopentane or HCFC 141b should be resistant.  

According to the invention, a multi-layer sheet for the Ent housing of a refrigerator or refrigerator wraps, the inner case being an excellent shiny external appearance and a favorable resistance ge compared to foaming agents such as CFC-11, cyclopentane and HCFC 141b has, and recycled and easily again as a resin material for that Inner case can be reused.

The invention aims to provide a multilayer sheet to provide for the inner housing of a refrigerator, wherein the inner case is an excellent shiny outer appearance has image.

Furthermore, according to the invention, a multilayer sheet is said to be be provided for the inner housing of a refrigerator, the inner case being easily recycled and used as a resin material can be reused without causing environmental problems can.

Furthermore, according to the invention, a multilayer sheet is said to be be provided for the inner housing of a refrigerator, which has a stress crack resistance to foaming agents, such as CFC-11, cyclopentane and HCFC 141b as well as balanced white has other physical properties.

The multi-layer fabric for an inner housing of a cooling cabinet, which is produced according to a coextrusion process has an inner layer made of an acrylonitrile / butadiene / styrene / (ABS) copolymer with an average molecular weight weight of 150 000∼300 000, which 10∼20 weight per percent of a butadiene rubber per ABS copolymer and 20∼45 Weight percent of an acrylonitrile per matrix made of styrene / Acrylni tril contains; and an outer layer of a styrene / acrylic ni tril (SAN) copolymer, which is a weight-average molecule lar weight of 100 000∼200 000, and which 20∼30 Ge contains percent by weight of an acrylonitrile.  

The thickness of the outer layer can preferably be in a range of 30-100 µm. If CFC-11 or Cyclopenthan as If foaming agent is used, the ABS copolymer 20∼35 Weight percent of an acrylonitrile per matrix of styrene / acrylic contain nitrile. On the other hand, if HCFC 141b as a foaming agent is used, the ABS copolymer 35∼45 weight pro zent as acrylonitrile per styrene / acrylonitrile matrix included ten.

In addition, the multi-layer fabric has the Erfin an inner layer made of a modified ABS copolymer on which 5∼25 percent by weight of a butadiene rubber per ABS copolymer and 35-45 weight percent of an acrylonitrile per Contains matrix of styrene / acrylonitrile, also a medium one Layer of an ABS copolymer, which is a weighted has a molecular weight of 150,000-300,000, which is 10-20 Weight percent of a butadiene rubber per ABS copolymer and 20-45 percent by weight of an acrylonitrile per matrix Contains styrene / acrylonitrile; and the fabric has one outer layer of a SAN copolymer, which gave way has average molecular weight of 100,000-200,000, and which contains 20-30 percent by weight of an acrylonitrile. The preferred thicknesses of the inner, middle and outer layers amount to 0.1∼1.0 mm, 1.0∼5.0 mm and 30∼100 µm, each.

The middle layer can be a recycled resin from the interior Have house, which was produced according to the invention is.

In the present application, "inner layer" means one Layer which the insulating material, such as polyurethane foam, contacted, "outer layer" means a layer that the inner walls of a refrigerator forms, and "middle layer" means a layer between the inner and the outer ren layer is co-extruded.  

The multi-layer fabric for an inner housing according to the Invention has a structure with two layers or three layers The multilayer sheet is made by means of a coextru sionsverfahren prepared, as it is for the expert can be carried out without the use of a binder.

In a two-layer fabric according to the invention, the inner layer, which contacts the insulating material an ABS resin, and the outer layer is covered with the inner layer co-extruded with a SAN resin.

The ABS resin for the inner layer should be of importance have a molecular weight of 150,000-300,000 and 10-20 % By weight of a butadiene rubber per ABS copolymer and 25-45 percent by weight of an acrylonitrile per matrix from Sty rol / acrylonitrile included. If the weight-average molecule larweight is less than 150,000, the thickness of the surface can formed after vacuum forming are no longer uniform.

On the other hand, if the weight average molecular weight Exceeds 300,000, difficulties arise with the Preparation of the resin or extrusion of the same.

If regarding the content of butadiene rubber this content is less than 10 percent by weight per ABS resin, the shock is strength of the fabric or the inner housing is insufficient Lich. On the other hand, if the content is over 20% by weight steps, is the stiffness of the fabric or the Inner casing unacceptable.

The content of an acrylonitrile in the styrene / acrylic matrix tril depends on the foaming agents used in the insulation material of a refrigerator can be used. If CFC-11 or Cyclopentane can be used as a foaming agent a preferred range of the acrylonitrile content to 20∼35 Weight percent per matrix of styrene / acrylonitrile,  and if HCFC 141b is used, the preferred one Range to 35-45 weight percent. Generally is the solubility of ABS resin to HCFC 141b greater than that of ABS resin to CFC-11 or cyclopentane. So if the salary of an acrylonitrile in the styrene / acrylonitrile matrix smaller than 35% by weight, a crack phenomenon occurs. If this, on the other hand, exceeds 45 percent by weight ABS resin has low processability during extrusion and vacuum forming.

The preferred thickness of the outer layer of the sheet can be in the range of 30∼100 µm.

The total thickness of the fabric is approximately 3∼5 mm, which is easy to understand for the expert. If the fat the outer layer exceeds 100 microns, the shock resistance reduced and it is no longer sufficient for that Inner case of a refrigerator. On the other hand, if the thickness of the outer layer is less than 30 microns, the fabric can no longer have an excellent gloss after vacuum forming.

In the two-layer fabric according to the invention, the inner layer, which is formed by an ABS resin, a preferred resistance to stress cracking over a foam pattern ner, and the outer layer, which is formed by a SAN resin gives this fabric a preferred glossy finish external appearance when the fabric becomes an in is vacuum-formed. To the inner and co-extrude outer layers in a preferred manner, the viscosity of the SAN resin should be approximately in the same range like those of the ABS resin.

As a result, the SAN resin should be a weight average molecular have a weight of 100,000-200,000 and 20-30 weight percent contain an acrylonitrile.  

For a three-layer fabric, which is a another preferred embodiment according to the invention, the fabric comprises an inner layer, a middle one Layer and an outer layer. The inner layer that the Insulated material is contacted by a modified ABS Resin formed, the outer layer of a SAN resin, and the middle layer is made of an ABS resin between the inner Layer and the outer layer formed.

In particular, the three-layer fabric is provided, excellent resistance to stress cracking To have foaming agents of the genus HCFC 141b. The modifi graced ABS resin that comes in contact with HCFC 141b is a ABS copolymer, which is 5-25% by weight of a butadiene chew tschuks per ABS resin and 35∼45 percent by weight of an acrylic ni tril per styrene / acrylonitrile matrix.

If the modified ABS resin less than 5 weight percent contains a butadiene rubber, cracks can form and there may be yellowing on the fabric during the vacuum reshaping occur. On the other hand, if the modified ABS resin contains more than 25 percent by weight of a butadiene rubber, may experience mechanical difficulties during extrusion result from the high viscosity. Even if the modified ABS resin less than 35 weight percent of an acrylonitrile per Styrene / acrylonitrile matrix can be used in use stood cracks and deformities occur. If others on the other hand, the modified ABS resin more than 45 percent by weight contains one acrylonitrile per matrix of styrene / acrylonitrile, may result in delamination from the middle class as a result of the mistake Adhesiveness to the middle layer occur.

The ABS resin for the middle layer of the three-layer surface the should have an average molecular weight of 150,000∼ Have 300,000 and 10-20 percent by weight of a butadiene chew Tschuks per ABS resin and 25∼45 percent by weight of an acrylic  trils per matrix made of styrene / acrylonitrile. The Grenzwer te for the molecular weight and the contents of the components for the same reasons as related to the two-layer fabric specified. There the multilayer fabrics according to the invention by a Coextrusion process without a binding material or binder are manufactured, the inner housing can be easily recycled and it can be reused as a resin material. The recy celte resin can be used as a resin material for the middle layer be taken. To preferably coextrude the three layers ren, the SAN resin should be a weight average molecular weight weight of 100,000-200,000 and 20-30 weight percent contain an acrylonitrile.

The preferred thicknesses of the inner, middle and outer Layers are 0.1∼1.0 mm, 1.0∼5.0 mm and 30∼ 100 µm, each. If the thickness of the inner layer is less than 0.1 mm, HCFC 141b can penetrate the inner layer, or the middle layer may be exposed to HCFC 141b because the inner layer of the inner housing up to 300 µm as a result of Stretching of the fabric during vacuum forming can get thin.

The invention is illustrated below by means of examples clarifies which are for illustration purposes only but not for Limitation of the scope of protection can be specified.

Examples

Example 1 is the preparation of a two-layer fabric which comprises an inner layer and an outer layer the invention, and a comparative example 1 is used for comparison with this example 1.  

example 1

An extruder with a feed block was used to coextrude one Two-layer fabric used. The extruder had one Main extruder with a screw diameter of 65 mm and one Sub-extruder with a screw diameter of 45 mm. Of the The main extruder was loaded with an ABS resin, and the sub extruder was loaded with a SAN resin. The middle tem temperatures of the main extruder and the sub-extruder at 210 ° C and 205 ° C, respectively. The screw speeds of the main extruder and the sub-extruder amounted to 80 l / min and 20 l / min respectively. The ABS resin to form a inner layer had a weight average molecular weight of 200,000 and contained 27 percent by weight of an acrylonitrile the matrix of styrene / acrylonitrile and 13 weight percent one Butadiene rubber in the ABS resin. The SAN resin for education an outer layer had a weight average molecular weight of 150,000 and contained 27 percent by weight of an acrylic nitrils.

The co-extruded sheet had a thickness of 3.0 mm and the thickness of the outer layer, which is made of a SAN resin was 50 µm. The outer layer of the flä Chengebildes had a gloss index of 99, which according to ASTM D 2457 (60 °) was measured.

The fabric was vacuum formed in a conventional manner and the gloss index was measured as previously mentioned. Here the gloss index was 98. The vacuum forming of the surface formed did not lead to a big difference in the shiny outer appearance. For the fabric the Falling Dart Impact (FDI) in accordance with ASTM D 3029 measured, and an impact resistance of 2900 N was obtained.  

Comparative Example 1

The procedure in Example 1 was carried out with the deviation that the operation of the sub-extruder has been stopped. The flat structure had a thickness of 3.0 mm and was only from an ABS Resin layer formed. The gloss index of the fabric and the vacuum molded article amounted to 96 and 92 respectively, resulting in a reduced gloss index after vacuum forming animals.

Three-layer fabrics were formed according to Examples 2-4 rides an inner layer, a middle layer and included an outer layer according to the invention, and Ver Comparative examples 2-4 were used for comparison with examples 2-4 executed.

Example 2

An extruder with a feed block was used to make one To co-extrude three-layer fabrics. The extruder had a main extruder with a screw diameter of 65 mm, a first sub-extruder with a screw diameter of 45 mm, and a second sub-extruder with a screw through knife of 40 mm. The main extruder was coated with an ABS resin sends, the first sub-extruder was modified ABS resin loaded, and the second sub-extruder with a SAN Resin. The mean temperatures of the main extruder and the first and second sub-extruders each amounted to 210 ° C, 220 ° C and 205 ° C. The screw speeds of the Main extruders and the first and second sub-extruders to 80, 40 and 20 l / min respectively. The modified ABS resin for coextrusion of an inner layer had a weighting average molecular weight of 110,000 and contained 40 weights percent of an acrylonitrile in the styrene / acrylonitrile matrix and 10 weight percent of a butadiene rubber in the ABS resin.  

The ABS resin to form a middle layer had a soft average molecular weight of 180,000 and contained 27 Weight percent of an acrylonitrile in the styrene matrix Acrylonitrile and 13 weight percent of a butadiene rubber in the ABS resin. The SAN resin to form an outer layer has a weight average molecular weight of 120,000 and contained 27 percent by weight of an acrylonitrile.

The thicknesses of the inner, middle and outer layers were 0.5 mm, 2.5 mm and 50 µm. That co-extruded Sheets had a gloss index of 99, which was made to measure ASTM D 2457 (60 °) was measured.

A refrigerator or refrigerator was with the three Layered fabrics made. HCFC 141b was considered a Foaming agent used in the refrigerator. With the cooling cabinet, 4-cycle heating and cooling tests were carried out. Everyone Test included an initial cycle in which the refrigerator -30 ° C for four hours, a second cycle, where he warmed up from -30 ° C to + 60 ° C for two hours was a third cycle in which it was four hours at about 60 ° C which was left long and a fourth cycle during which cooling from 60 ° C to -30 ° C took place over two hours. As a result of the test, no cracks or deformity could be found NEN can be found on the inner housing. A yellowing The index of the inner case was determined in accordance with JIS K 7103 measured and amounted to 0.1.

Example 3

The procedure of Example 2 was otherwise followed by led that the modified ABS resin to form an inner Layer has an average molecular weight of 120,000 had and 35 percent by weight of an acrylonitrile in the matrix  made of acrylonitrile / styrene and 10 percent by weight of a butadiene rubber contained in the ABS resin. As a result of a four Cycles of heating and cooling tests could not crack conditions or deformations on the inner housing. The gloss index was 99 and the yellowness index was 0.2 measured.

Example 4

The procedure of Example 2 was followed, apart from that causes the ABS resin to coextrude a middle layer 15 % By weight of a resin contained, which from the Innenge housing was obtained by recycling, which according to the example 2 has been produced. As a result of four cycles Send heating and cooling tests could not crack or Deformation can be found on the inner housing. The shine index was 99 and the yellowness index was 0.2 according to the measurements.

Comparative Example 2

The procedure of Example 2 was otherwise followed by led that the modified ABS resin for coextrusion of a inner layer has a weight average molecular weight of 130,000 and 32 percent by weight of an acrylonitrile in the Matrix of styrene / acrylonitrile and 10 percent by weight of a buta service rubber contained in the ABS resin. As a result of a four Cycles of heating and cooling tests were cracked observed on the inner case. The gloss index was after the measurements to 99 and the yellowness index to 0.1.  

Comparative Example 3

The procedure of Example 2 was otherwise followed by led to the operation of the first and second sub-extruders was stopped. The sheet had a thickness of 3.0 mm and included only one layer of ABS resin. As a result of one Four cycles of heating and cooling tests showed cracks found on the inner housing. The gloss index was after measurements to 96 and the yellowness index to 0.1.

Comparative Example 4

The procedure of Example 3 was otherwise followed by led that the modified ABS resin after the comparison game 2 was used instead of the ABS resin, and that the average temperature of the main extruder is about 220 ° C. ran. As a result, four cycles of heating and cooling tests could not fix cracks on the inner housing be put. The gloss index was 95 and the yellow Coloring index to 1.3 according to the measurements.

Claims (9)

1. Two-layer flat structure for an inner housing of a refrigeration machine (refrigerator), which is produced by means of a coextrusion process, characterized by the following:
an inner layer of an acrylonitrile / butadiene / - styrene (ABS) copolymer, which has a weight-average molecular weight of 150,000-300,000, and 10-20 percent by weight of a butadiene rubber per ABS copolymer and 20-45 percent by weight of an acrylonitrile per matrix made of styrene / acrylonitrile; and
an outer layer of a styrene / acrylonitrile (SAN) copolymer, which has a weight-average molecular weight of 100,000-200,000, and contains 20-30 percent by weight of an acrylonitrile. 2. Two-layer fabric according to claim 1, characterized records that the ABS copolymer 20∼35 weight percent one acrylonitrile per styrene / acrylonitrile matrix contains the case when CFC-11 or cyclopentane as a Foaming agent is used. 3. Two-layer fabric according to claim 1, characterized records that the ABS copolymer 35-45 weight percent one acrylonitrile per styrene / acrylonitrile matrix for includes the case that HCFC 141b as a foaming agent is set. 4. Two-layer fabric according to claim 1, characterized records that the outer surface has a thickness of 30∼100 microns Has.   5. Three-layer flat structure for an inner housing of a refrigeration machine (refrigerator), which is produced by means of a coextrusion process, characterized by the following:
an inner layer of a modified ABS copolymer, which contains 5-25% by weight of a butadiene rubber per ABS copolymer and 35-45% by weight of an acrylonitrile per matrix of styrene / acrylonitrile; a middle layer of an ABS copolymer which has a weight average molecular weight of 150,000∼300,000 and which contains 10∼20 percent by weight of a butadiene rubber per ABS copolymer and 20∼45 percent by weight of an acrylonitrile per matrix of styrene / acrylonitrile; and
an outer layer of a SAN copolymer, which has a weight average molecular weight of 100,000∼200,000, and 20∼30 percent by weight of an acrylonitrile. 6. three-layer fabric according to claim 5, characterized records that the inner layer has a thickness of 0.1-1.0 mm. 7. three-layer fabric according to claim 6, characterized records that the middle layer has a thickness of 1.0∼5.0 mm. 8. three-layer fabric according to claim 7, characterized records that the outer layer has a thickness of 30∼100 microns Has. 9. Three-layer fabric according to one of claims 5 to 8, characterized in that the middle layer ABS resin obtained by recycling, which a a weight-average molecular weight of 150,000∼ 300,000, and 10-20 percent by weight of a butadiene rubber per ABS copolymer and 20∼45 weight percent one acrylonitrile per styrene / acrylonitrile matrix holds.