JPH0311262B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a resin laminate, and more particularly to a resin laminate that has good appearance and interlayer adhesion, and also has excellent chemical resistance. Generally, a laminate of foamed urethane and polystyrene using a low boiling point halogenated alkane as a blowing agent is used as a heat insulating material for the inner box of a refrigerator. However, polystyrene is easily corroded by the low boiling point halogenated alkane which is a blowing agent, and if the polystyrene layer is thin, it has the disadvantage that the side opposite to the side in contact with the urethane foam layer is corroded, resulting in poor appearance. Therefore, it has been proposed to use a laminate of ABS resin and urethane foam, which are resistant to low-boiling halogenated alkanes. However, ABS
Although the resin is resistant to low-boiling halogenated alkanes, it has drawbacks such as poor moldability and high price. Another known method is to cover the polystyrene layer with a polyolefin film or the like to protect the surface and then perform urethane foaming to laminate the layers. There are drawbacks such as bad. The inventors of the present invention have made extensive studies in order to eliminate the above-mentioned conventional drawbacks. As a result, it has excellent chemical resistance,
A resin composition in which an inexpensive polypropylene resin that is resistant to low-boiling halogenated alkanes is used in place of polystyrene, and an ethylene-vinyl acetate copolymer or a modified polypropylene resin is added to the copolymer as an adhesive layer. The inventors have discovered that a resin laminate with good appearance and interlayer adhesion as well as excellent chemical resistance can be obtained by using this method, and have completed the present invention. That is, the present invention provides a resin layer (A) made of either an ethylene-vinyl acetate copolymer or a resin composition made of an ethylene-vinyl acetate copolymer and a polypropylene resin modified with an unsaturated carboxylic acid or a derivative thereof. The present invention provides a resin laminate in which a polypropylene resin layer (B) and a foamed urethane layer (C) are laminated via a polypropylene resin layer (B) and a foamed urethane layer (C). In the present invention, the adhesive layer (A) is an ethylene-
It consists of either a vinyl acetate copolymer alone or a resin composition in which the copolymer is blended with a polypropylene resin modified with an unsaturated galboxic acid or a derivative thereof. There are no particular restrictions on the ethylene-vinyl acetate copolymer, but the vinyl acetate content is 5 to 70% by weight and the melt index (MI) is 0.5 to 100g/
10 minutes is preferably used. If the vinyl acetate content is less than 5% by weight, sufficient adhesive strength cannot be obtained. On the other hand, if it exceeds 70% by weight, the elastic modulus and tensile strength of the adhesive layer will also be low, resulting in insufficient strength of the adhesive layer at the operating temperature. For layer (A), the above ethylene-vinyl acetate copolymer may be used alone, but a resin composition in which the copolymer is blended with a polypropylene resin modified with an unsaturated carboxylic acid or a derivative thereof is used. You can also do that. By using such a resin composition, the adhesive strength with the polypropylene resin layer (B) can be further improved. The above-mentioned polypropylene resin modified with an unsaturated carboxylic acid or a derivative thereof means a polypropylene resin modified with an unsaturated carboxylic acid or a derivative thereof, or a mixture of the modified polypropylene resin and an unmodified polypropylene resin. Examples of polypropylene resins include propylene homopolymers, block copolymers of propylene and other α-olefins such as ethylene, and random copolymers. Examples of the unsaturated carboxylic acids used for modifying the polypropylene resin include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, citraconic acid, sorbic acid, mesaconic acid,
including angelic acid. Further, its derivatives include acid anhydrides, esters, amides, imides, metal salts, etc., such as maleic anhydride, itaconic anhydride, citraconic anhydride, methyl acrylate, methyl methacrylate, ethyl acrylate,
Examples include butyl acrylate, monoethyl maleate, acrylamide, monoamide maleate, maleimide, N-butylmaleimide, sodium acrylate, and sodium methacrylate. The method for modifying polypropylene resin with these unsaturated carboxylic acids or derivatives thereof is not particularly limited, and various known methods can be used. For example, a radical initiator is added to polypropylene resin and maleic anhydride in the presence or absence of a solvent, and the mixture is heated. During the reaction, other vinyl monomers such as styrene or rubbers such as liquid rubber and thermoplastic rubber may also be present. The amount of acid addition of the unsaturated carboxylic acid or its derivative in the modified polypropylene resin thus obtained is usually 0.001 to 13% by weight, preferably 0.01% by weight.
~6% by weight. When using a resin composition in which the above-mentioned ethylene-vinyl acetate copolymer is blended with a polypropylene resin modified with an unsaturated carboxylic acid or its derivatives as layer (A), the latter modified polypropylene resin is
It is blended in an amount of 0.1 to 60% by weight, preferably 5 to 30% by weight. If the blending ratio of modified polypropylene exceeds 60% by weight, it is not preferable because the adhesion to the layer (C) described later, that is, the foamed urethane layer, deteriorates.
Moreover, if it is less than 0.1% by weight, the adhesive strength with the polypropylene resin layer (B) cannot be further improved. Next, the polypropylene resin for layer (B) in the resin laminate of the present invention includes a propylene homopolymer and a copolymer of propylene and other α-olefins such as ethylene, and the α-olefin content is 30%.
It is appropriate that the amount is less than % by weight. Further, the foamed urethane of layer (C) in the resin laminate of the present invention is a foamed polyurethane resin. Polyurethane resins can be obtained by reacting diisocyanates such as tolylene diisocyanate; diphenylmethane-4,4'-diisocyanate with polyols such as propylene glycol and trimethylolpropane. A foamed urethane can be obtained by foaming this polyurethane resin using a low boiling point halogenated alkane such as trichloromonofluoromethane, methylene chloride, monochlorodifluoromethane, or dichlorodifluoromethane as a foaming agent. The method for foaming the polyurethane resin is not particularly limited, and may be injection foaming or spray foaming using a well-known method such as a non-frosting method or a frothing method. In addition, by using a low boiling point halogenated alkane as the blowing agent as described above, the consumption of diisocyanates is small, the production cost is low, and a foamed urethane with excellent heat insulation properties can be obtained. The resin laminate of the present invention can be obtained by laminating the above (A), (B), and (C) layers with the (B) layer and (C) layer via the (A) layer. Here, the lamination method can be performed by a known method. For example, after producing a two-layer sheet by co-extruding the polypropylene resin that is a component of the (B) layer and the component of the (A) layer (adhesive layer), the (A) layer (adhesive layer)
A resin laminate can be obtained by foaming a polyurethane resin on the side using a foaming agent. The thickness of each layer in the resin laminate of the present invention varies depending on the purpose of use of the laminate and is not uniquely determined, but usually (B) layer / (A layer) / (C) layer = 0.5 to 3.5
mm/0.005~1.0mm/5~100mm, preferably 0.8~
2.5mm/0.05~0.2mm/5~50mm. The resin laminate of the present invention is thus made of ethylene-
A polypropylene resin layer is formed through a resin layer (A) made of either a vinyl acetate copolymer or a resin composition made of a polypropylene resin modified with an ethylene-vinyl acetate copolymer and an unsaturated carboxylic acid or a derivative thereof. (B) and a foamed urethane layer (C) are laminated, so it has excellent interlayer adhesion. In addition, the polypropylene resin that is a component of layer (B) is inexpensive and has excellent chemical resistance, as well as resistance to low-boiling halogenated alkanes, so the resin laminate of the present invention has a good appearance. . Therefore, the resin laminate of the present invention can be effectively used as a heat insulating material for various products, particularly for the inner box of a refrigerator. Next, examples of the present invention will be shown. Example 1 Ethylene-vinyl acetate copolymer (vinyl acetate content 26% by weight, M 14 g/10 min) and propylene homopolymer (MI 2.0 g/10 min, density 0.91 g/cc) were mixed at 200 g/cc.
Coextruded at °C, ethylene-vinyl acetate copolymer ((A) layer) 0.1 mm, polypropylene resin ((B) layer) 2 mm
A laminate with a thickness of . Next, a polyurethane foam layer is formed on the (A) layer side of this laminate, that is, on the adhesive layer side, by the following method, and a resin laminate consisting of three layers (A), (B), and (C) is formed. I got a body. First, sugar (sugar) and glycerin are mixed at a ratio of 3:1 by weight, and propylene oxide is added by a known method to increase the hydroxyl value to 400.
A polyether polyol having mg·KOH/g and a viscosity of 4000 cps/25°C was obtained (this will be referred to as "Polyol A"). Next, in a container, 100 parts by weight of the polyol A, 2 parts by weight of an amine catalyst (Dabco33LV, manufactured by Sankyo Air Products), 0.8 parts by weight of dimethylethynolamine (DMEA) as a promoter, and silicone SH-193 (Toray (Manufactured by Silicone Inc.) 1.5 parts by weight and trichloromonofluoromethane as a blowing agent
Take 54 parts by weight and thoroughly mix it as the main ingredient, add 103 parts by weight of crude MDI (diphenylmethane-4,4'-diisocyanate) (NCO content: 30.5%) as a curing agent, and stir for 10 seconds. Mixed. Next, the solution obtained with this mixing ratio was poured into an aluminum mold (length 15 cm, width 10 cm, depth 5 cm) in which the two-layer laminates (A) and (B) created earlier were set. An aluminum lid was placed in a press molding machine, and the foaming pressure was applied to an extent that the lid would not be pushed up. Foaming is completed in about 140 seconds, and (A), (B),
The resin laminate consisting of three layers (C) was taken out. The density of the resulting urethane foam layer (C) is 0.033.
g/cm ³ and the thickness was about 5 cm. Table 1 shows the adhesive strength of the resin laminate obtained. Example 2 In Example 1, 90% by weight of ethylene-vinyl acetate copolymer (vinyl acetate content 26% by weight, MI 4g/10min) and maleic anhydride-modified polypropylene (anhydrous) were used instead of ethylene-vinyl acetate copolymer. Maleic acid addition amount 6% by weight, MI90g/10min) 10
A resin laminate was obtained in the same manner as in Example 1 except that a resin composition consisting of % by weight was used. Table 1 shows the adhesive strength of the resin laminate obtained. Example 3 In Example 2, the amount of maleic anhydride added was 2% by weight as the maleic anhydride-modified polypropylene.
A resin laminate was obtained in the same manner as in Example 2 except that a resin laminate was used. Table 1 shows the adhesive strength of the resin laminate obtained. Example 4 A resin laminate was obtained in the same manner as in Example 2, except that the amount of maleic anhydride-modified polypropylene was 25% by weight. Table 1 shows the adhesive strength of the resin laminate obtained. Example 5 In Example 4, the amount of maleic anhydride added was 2% by weight as maleic anhydride-modified polypropylene.
A resin laminate was obtained in the same manner as in Example 4 except that a resin laminate was used. Table 1 shows the adhesive strength of the resin laminate obtained. Comparative Example 1 Polyurethane resin was applied to a sheet (thickness 2 mm) of propylene homopolymer (MI 2.0 g/10 min, density 0.91 g/cc) in the same manner as in Example 1, using trichloromonofluoromethane as a blowing agent. Foamed urethane was laminated to a thickness of 5 cm. This laminate did not adhere. Reference example 1 Impact-resistant polystyrene with a thickness of 2 mm (MI2.0g/
10 minutes), polyurethane resin was foamed using trichloromonofluoromethane in the same manner as in Example 1, and 5 cm thick urethane foam was laminated to obtain a two-layer resin laminate. After holding this resin laminate at -20℃ for 2 hours,
The temperature was rapidly raised to 50°C and held for 2 hours. After repeating this operation three times, the impact-resistant polystyrene layer was visually observed. As a result, many corroded parts were observed in the layer.

[Table] *1 Ethylene-vinyl acetate copolymer *2 Between (B) layer and (C) layer

Claims (1)

[Scope of Claims] 1. A resin layer (A ) through polypropylene resin layer (B) and urethane foam layer
A resin laminate made by laminating (C). 2. The resin laminate according to claim 1, wherein the foamed urethane layer (C) is obtained by using a low boiling point halogenated alkane as a blowing agent.