JPH0948081A - Laminate - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a laminated body that does not generate an avatar phenomenon or a charge mark when vacuum molding or stamping molding is performed. A reactive monomer having two functional groups (for example,
1,10-decanediol dimethacrylate) on at least one surface of a foam A made of a thermoplastic resin containing
A laminated body in which a foamed body B made of a thermoplastic resin containing a reactive monomer having a functional group number of 3 (for example, trimethylolpropane trimethacrylate) is laminated.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a laminate suitable for vacuum forming or stamping forming.

[0002]

2. Description of the Related Art Foams have been molded and commercialized using ordinary molding methods such as vacuum molding for ceiling materials, door materials, interior materials for vehicles such as instrument panels, and heat insulating materials for houses. There is. At that time, when vacuum forming is used as the forming method, a weak portion of the foam film of the foam is broken by heat and the broken portion is contracted to cause unevenness on the foam surface, a so-called avatar phenomenon occurs. Or, when stamping molding is used, when the base resin is injected into the mold, the foam is destroyed by contact with the high temperature resin, and the destruction reaches the foam surface, There was a problem that unevenness, so-called charge marks, occurred on the surface.

Therefore, in order to solve the above problems, it has been attempted to add a bifunctional monomer and a monofunctional monomer to the expandable polyolefin resin composition (JP-A-5-1170). However, even if a bifunctional monomer or the like is added, the heat resistance of the obtained foam is still insufficient, and the avatar phenomenon and charge mark cannot be prevented.

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a laminate which does not cause an avatar phenomenon or a charge mark even when it is formed by vacuum forming or stamping forming.

The present invention has two functional groups.
The foam B containing the reactive monomer having a functional group number of 3 on at least one surface of the foam A containing the reactive monomer
Is in a laminated body.

The thermoplastic resin used in the foam A or the foam B is not particularly limited as long as it is usually used in foam applications. For example, linear low density polyethylene, low density polyethylene, and medium density polyethylene. , Polyethylene resins such as high-density polyethylene and ultra-low-density polyethylene, homopolypropylene, propylene component and α-olefin (eg, ethylene, 1-hexene, 4-methyl-
1-pentene, 1-octene, 1-butene, 1-pentene, etc.) polypropylene resins such as random copolymers and block copolymers, ethylene-vinyl acetate copolymers, polystyrene, polyvinyl chloride, polychlorine Examples thereof include chemical vinyl chloride, and these may be used alone or in combination of two or more kinds. Among these, it is preferable to use a resin containing 40 to 90% by weight of a polypropylene resin in order to improve moldability. The polypropylene resin has a melt index (MI) of 0.3 to 1.
0 is preferred. The polyethylene resin preferably has a melt index of 1.0 to 20, and linear low density polyethylene is particularly preferable. In the present invention, the melt index refers to that measured according to JIS K7210.

In the present invention, in order to improve the heat resistance of the surface of the laminated body and prevent the avatar phenomenon and the charge mark, a part of the laminated body is a foam B containing a reactive monomer having a functional group number of 3. .

The reactive monomer having 3 functional groups is not particularly limited, and examples thereof include trimethylolpropane trimethacrylate, triallyl trimate, triallyl cyanurate, and the like, which may be used alone. Two or more kinds may be mixed and used.

Foam B of reactive monomer having 3 functional groups
If the content is low, it becomes difficult to crosslink, and if the content is high, the reactive monomer bleeds out to lower the surface property of the laminate, or the reactive monomer becomes uniform when the foamable resin sheet is produced. Since it may not be dispersed, 0.5-
30% by weight is preferable, and 1.5 to 15% by weight is more preferable.

In the present invention, in order to maintain the formability,
A part of the laminate is a foam A containing a reactive monomer having 2 functional groups.

Examples of the reactive monomer having 2 functional groups include 1,6-hexadiol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, and 1,10-decanediol di (meth). ) Acrylate, divinylnaphthalene, divinyltoluene, etc. may be mentioned, and these may be used alone or in combination of two or more kinds.

Foam B of reactive monomer having 2 functional groups
The content thereof is preferably 0.5 to 30% by weight, and is preferably 1.5 to 15 for the same reason as that of the reactive monomer having 3 functional groups.
% By weight is more preferred.

In the laminate of the present invention, if the ratio of the thickness of foam A to the thickness of foam B (thickness of foam A / thickness of foam B) is large, the heat resistance of the laminate is lowered, On the other hand, if it is too small, the moldability of the laminate will be deteriorated. When the foam B is laminated on both sides of the foam A, the thickness of the foam B means the total thickness thereof.

Next, a method for manufacturing the laminate of the present invention will be described. First, a foamable resin sheet is produced, but the method is not particularly limited. For example, a foamable resin containing a reactive monomer having a functional group of 2 and a foamable resin containing a reactive monomer having a functional group of 3 are used. In addition to the method of producing a foamable resin sheet by laminating the co-extrusion, a foamable resin sheet containing a reactive monomer having a functional group of 2 and a foamable resin sheet containing a reactive monomer having a functional group of 3 are separately produced. Then, a method for producing a foamable resin sheet by subjecting these to hot lamination is mentioned.

The expandable resin sheet comprises a resin, a reactive monomer and a foaming agent, and if necessary, additives such as a crosslinking aid, an antioxidant and a pigment. The foaming agent is not particularly limited as long as it is used in foam production, and examples thereof include azodicarbonamide, hydrazodicarbonamide, azodicarboxylic acid amide, azodicarboxylic acid barium salt, dinitrosopentaethylenetetramine and nitroso. Examples include guanidine, p, p'-oxybisbenzenesulfonyl semicarbazide, trihydrazine symmetric triazine, bisbenzenesulfonyl hydrazide barium azodicarboxylate, azobisisobutyronitrile, toluenesulfonyl hydrazide, which are used alone. Alternatively, two or more kinds may be mixed and used. The amount of the foaming agent added is appropriately adjusted according to the expansion ratio of the foam, but if it is large, it will break, and if it is small, it will not foam, so 1 to 50 parts by weight is preferable relative to 100 parts by weight of the resin, It is more preferably 1 to 30 parts by weight.

The laminate can be obtained by subjecting the expandable resin sheet obtained as described above to electron beam cross-linking or chemical cross-linking, and heating / foaming by a usual heating means. When a cross-linking treatment is carried out, if the degree of cross-linking is high, not only a high foam cannot be obtained, but also the moldability decreases, and if it is low, a foam with a high expansion ratio cannot be obtained. It is preferable to perform the crosslinking treatment so that the gel fraction is preferably 20 to 75% by weight, more preferably 30 to 60% by weight. In the present invention, the gel fraction is 120
The weight percentage of the dry residue weight after immersion in xylene at 0 ° C. for 24 hours with respect to the weight before immersion.

In the laminate of the present invention, a skin material may be laminated on the side of the foam B for use. As such a skin material,
There is no particular limitation, and examples thereof include polyester-based, polyamide-based, acrylic-based synthetic fibers, cloths made of natural fibers such as cotton and silk, vinyl chloride-based resins, synthetic resin sheets made of thermoplastic elastomer, and the like. The lamination of the laminate and the skin material is not particularly limited, and may be an adhesive or heat fusion.

The foam A is cross-linked with a reactive monomer having a functional number of 2. The cross-linked structure using a reactive monomer having a functional number of 2 is considered to be a gentle cross-linked or bundle-type cross-linked structure, the movement of the molecular chain is smooth against stress, and the foam A has a high degree of elongation. It has a high degree of moldability. Further, the foam B is cross-linked by using a reactive monomer having 3 functional groups. The crosslinked structure using a reactive monomer having a functional group of 3 is considered to have a strong crosslinked structure, and at the time of crosslinking, the decrease in the molecular weight of the resin can be minimized, and the foam B has heat resistance. It is excellent.

[0016]

【Example】

(Examples 1, 2 and Comparative Examples 1 to 3) Extruders A, B and C of 3
In each extruder, 70 parts by weight of a polypropylene resin (propylene-ethylene random copolymer having an ethylene content of 4.8% by weight, MI = 1.8), a polyethylene resin (density 0.920 g / cm ³ Linear low-density polyethylene, MI = 2.0) 30 parts by weight, azodicarbonamide 9 parts by weight as a foaming agent, antioxidant (BHT)
0.5 parts by weight and the amount of trimethylolpropane trimethacrylate (TM) shown in Table 1 as the reactive monomer
P) or 1,10-decanediol dimethacrylate (DD) is supplied and coextruded so that the resin thickness ratios extruded from the extruders A, B and C are as shown in Table 1 to obtain a foamable resin sheet. Obtained. Both sides of the obtained foamable resin sheet were irradiated with an electron beam (800 kv) of 3.5 Mrad,
After crosslinking, this was heated to 280 ° C. to obtain a laminate. The physical properties of the obtained laminate were measured by the following methods, and the results are shown in Table 1.

Presence or Absence of Avatar Phenomenon In the obtained laminate, a urethane adhesive is applied to the foam surface obtained by foaming the resin extruded from the extruder A and dried, and then the surface is heated to soft chloride. A skin material made of a vinyl resin sheet (thickness 0.4 mm) was pressed and attached to obtain a laminate with skin material. At this time, the presence or absence of irregularities on the surface of the skin material was visually confirmed, and those without irregularities were regarded as acceptable. In addition, in Table 1, all those that passed are “none”,
If there was even one failure, it was designated as "Yes".

Vacuum Formability The laminate with the skin material was heated to 180 ° C. and vacuum-formed using a concave portion of a cylindrical mold having a drawing ratio (diameter 500 mm) of 0.8 so that the skin material has a convex surface. . A product that could be molded into a cup shape without tearing the laminate was regarded as acceptable. In addition, in Table 1, those that passed all were regarded as "good", and those that failed even one were regarded as "bad".

Presence or absence of charge mark The laminate with the skin material is heated to 190 ° C., and preliminarily applied by using a concave portion of a cylindrical mold having a drawing ratio (diameter 100 mm) of 0.6 so that the skin material has a convex surface. Typed The obtained preformed laminate was placed in a mold while keeping the skin material side toward the female mold side while being kept at 190 ° C, and 210 ° C polypyropyrene was placed between the laminate and the male mold. Was injected and the mold was clamped to obtain a molded body. The surface of the skin material of the obtained molded product was visually observed, and a product without a charge mark was regarded as acceptable. In addition, in Table 1, those that were all passed were defined as "no" and those that were even failed were "present".

[0020]

[Table 1]

All of the above three evaluations are "none" or "good".
Those that were evaluated as "Comprehensive" were evaluated as comprehensive evaluation, and those that were not evaluated as "Failed".

In the laminate of the present invention, the foam B containing the reactive monomer having the functional group number of 3 is laminated on at least one surface of the foam A containing the reactive monomer having the functional group number of 2. Is characterized by. The foam A obtained by cross-linking with a reactive monomer having a functional number of 2 is as described above.
It is excellent in moldability but inferior in heat resistance. on the other hand,
The foam B obtained by crosslinking with a reactive monomer having 3 functional groups has excellent heat resistance but poor moldability as described above. The laminated body of the present invention is one in which the foamed body B is laminated on at least one surface of the foamed body A, so that the defects of each foamed body are compensated for while maintaining the characteristics of both foamed bodies. Therefore, when performing vacuum forming using the laminate of the present invention, if the laminate is set and formed so that the noticeable portion becomes the foam B (or the skin material when the skin material is laminated), the avatar can be formed. It is possible to obtain a molded product having a complicated shape, which is excellent in surface property and has no phenomenon. When stamping molding, the visible part is the foam B.
When the laminate is set and molded so as to be (a skin material when the skin material is laminated), a molded product having no charge mark, excellent surface properties, and a complicated shape can be obtained.

Claims (2)

[Claims] 1. A foam A made of a thermoplastic resin containing a reactive monomer having a functional number of 2 is provided on at least one surface of the foam A.
A laminated body in which a foamed body B made of a thermoplastic resin containing a reactive monomer having a functional group number of 3 is laminated. 2. The polypropylene resin 4 as the thermoplastic resin.
The laminate according to claim 1, which contains 0 to 90% by weight.