JP2019064076A - Laminate - Google Patents

Abstract

To provide a laminate which has a resin film as a reinforcement material of a resin foam sheet, and can easily peel the resin film from the resin foam sheet without impairing performance of a resin foam sheet when the resin film is peeled from the resin foam sheet.SOLUTION: A laminate is formed by laminating a resin sheet (A) and a resin foam sheet (B), where 180° peel strength of the resin sheet (A) and the resin foam sheet (B) is 0.02 to 0.50 N/25 mm. In the laminate, the resin sheet (A) is formed of one or more selected from polyethylene, polypropylene, polyethylene terephthalate or polyamide, and the resin foam sheet (B) is formed of a resin containing linear polyethylene polymerized using a metallocene catalyst as a main component.SELECTED DRAWING: None

Description

  The present invention relates to a laminate including a resin sheet and a resin foam sheet.

  Conventionally, porous resin materials in which a large number of holes are formed in the resin layer are excellent in, for example, buffer properties, heat insulation properties, waterproof properties, and moisture proof properties, and thus protection from article packaging materials, gases or liquids is required. It is used for various applications, such as a sealing material which seals a peripheral part of a part, a case, etc., a shock absorbing material which damps vibration and impact, a base material of an adhesive sheet, etc. For example, Patent Document 1 discloses a crosslinked polyolefin resin foam sheet obtained by foaming and crosslinking a foamable polyolefin resin sheet containing a thermal decomposition-type foaming agent (see, for example, Patent Document 1).

In recent years, in various electronic devices such as mobile phones, IT devices such as personal computers, digital cameras, and small video cameras, resin foam sheets used inside these electronic devices are also thin layers as the products become smaller and thinner. It is desirable to
However, the thin resin foam sheet is weak in mechanical strength, and when processed, there is a problem that elongation, breakage, wrinkles and the like are easily generated. In order to prevent this, it is desirable that the resin foam sheet be processed while being supported by a support for reinforcing mechanical strength.

As a method of providing a support on a resin foam sheet, for example, a composition serving as a raw material of a resin foam sheet is applied onto a resin film which is a support, and the composition is foamed on the support. And a method of obtaining a laminate of a support and a resin foam sheet. However, according to this method, since the support and the resin foam sheet become an integrated laminate, the support can not be separated from the resin foam sheet, and the compression characteristics of the resin foam sheet are impaired. There was a case.
Moreover, as another method of providing a support body in a resin foam sheet, the method of sticking the support body which has an adhesive layer on the surface facing a resin foam sheet on a resin foam sheet is mentioned. However, according to this method, after peeling the support, there may be a problem in the resin foam sheet such as a component derived from the pressure-sensitive adhesive layer remaining on the surface of the resin foam sheet.

WO 2005/007731

  The present invention has been made in view of the above circumstances, and when a resin film as a support effectively functions as a reinforcing material for a resin foam sheet, and when the resin film is peeled from the resin foam sheet. An object of the present invention is to provide a laminate that can be easily peeled off without causing a defect in a resin foam sheet.

As a result of intensive studies to achieve the above object, the present inventors are a laminate formed by laminating a resin sheet as a support and a resin foam sheet, wherein the resin sheet and the resin foam sheet The inventors found that a laminate in which the 180 ° peel strength thereof was adjusted to a specific range could solve the above problems, and completed the present invention.
That is, the present invention provides the following [1] to [10].
[1] A laminate formed by laminating a resin sheet (A) and a resin foam sheet (B), wherein the 180 ° peel strength between the resin sheet (A) and the resin foam sheet (B) is 0 The laminated body which is .02-0.50 N / 25 mm.
[2] The laminate according to the above [1], wherein the resin sheet (A) contains as a main component one or more selected from polyethylene, polypropylene, polyethylene terephthalate and polyamide.
[3] The lamination according to the above [1] or [2], wherein the arithmetic average surface roughness Ra of the surface of the resin sheet (A) facing the resin foam sheet (B) is 0.5 μm or less body.
[4] The laminate according to any one of the above [1] to [3], which does not have an adhesive coating layer between the resin sheet (A) and the resin foam sheet (B).
[5] The laminate according to any one of the above [1] to [4], wherein the resin foam sheet (B) is mainly composed of linear polyethylene polymerized using a metallocene catalyst.
[6] The arithmetic mean surface roughness Ra of the surface of the resin foam sheet (B) on the side facing the resin sheet (A) is 1.0 to 15.0 μm in the above [1] to [5] The laminated body in any one.
[7] The laminate according to any one of the above [1] to [6], wherein the apparent density of the resin foam sheet (B) is 0.05 to 0.75 g / cm ³ .
[8] The laminate according to any one of the above [1] to [7], wherein the thickness of the resin foam sheet (B) is 0.05 to 3.0 mm.
[9] The laminate according to any one of the above [1] to [8], wherein the tensile elastic modulus of the resin foam sheet (B) is 0.5 to 50.0 MPa.
[10] At least one of the surface of the resin sheet (A) facing the resin foam sheet (B) and the surface of the resin foam sheet (B) facing the resin sheet (A) The laminated body in any one of said [1]-[9] which is what is corona-treated.

  According to the present invention, the resin film effectively functions as a reinforcing material for the resin foam sheet, and when the resin film is peeled from the resin foam sheet, the resin foam sheet does not have a problem. It is possible to provide a laminate that can be easily peeled off.

Hereinafter, the present invention will be described in detail using embodiments.
[Laminate]
The laminate of the present invention is a laminate formed by laminating a resin sheet (A) and a resin foam sheet (B), and the 180 ° peeling of the resin sheet (A) and the resin foam sheet (B) It is a laminated body whose intensity is 0.02 to 0.50 N / 25 mm.

<180 ° peel strength>
The 180 ° peel strength between the resin sheet (A) and the resin foam sheet (B) in the laminate of the present invention (hereinafter, also simply referred to as “peel strength”) is 0.02 to 0.50 N / 25 mm.
The laminate of the present invention can effectively function the resin film (A) as a reinforcing material for the resin foam sheet (B) by setting the above-mentioned peel strength to 0.02 N / 25 mm or more. Handleability and processability of the body sheet (B) can be improved. On the other hand, when peeling the resin film (A) from the resin foam sheet (B) by setting the peel strength between the resin sheet (A) and the resin foam sheet (B) to 0.50 N / 25 mm or less Thus, the resin foam sheet (B) can be easily peeled off without causing a problem.

On the other hand, when the peel strength between the resin sheet (A) and the resin foam sheet (B) is less than 0.02 N / 25 mm, the adhesion strength is too low, and the resin sheet (A) is a resin foam sheet It becomes difficult to reinforce the mechanical strength of (B). Moreover, when the peel strength between the resin sheet (A) and the resin foam sheet (B) exceeds 0.50 N / 25 mm, the adhesion strength becomes too high, and the resin foam sheet (B) When the resin foam sheet (B) is peeled off, it becomes difficult to peel off without damaging the resin foam sheet (B).
The 180 ° peel strength between the resin sheet (A) and the resin foam sheet (B) is 0. 0 in order to be able to peel the release sheet (A) without damaging the resin foam sheet (B). 02-0.5 N / 25 mm is preferable, 0.02-0.4 N / 25 mm is more preferable, and 0.03-0.3 N / 25 mm is still more preferable.
The 180 ° peel strength can be adjusted by the material of the resin sheet (A) and the resin foam sheet (B) described later, the surface treatment method, and the like.
The 180 ° peel strength in the present specification can be determined by the method described in the examples.
Hereinafter, the resin sheet (A) and the resin foam sheet (B) provided in the laminate of the present invention will be described in order.

<Resin sheet (A)>
The resin sheet (A) is a resin sheet which plays a role as a support of the resin foam sheet (B).
The resin sheet (A) reinforces the mechanical strength of the resin foam sheet (B) as a support at the time of processing, and is peeled from the resin foam sheet (B) before and after lamination processing such as coating and laminating. Ru.

(Arithmetic average surface roughness Ra of resin sheet (A))
The arithmetic mean surface roughness Ra of the surface of the resin sheet (A) on the side facing the resin foam sheet (B) is preferably 0.5 μm or less. By setting the arithmetic average surface roughness Ra to 0.5 μm or less, the adhesion between the resin sheet (A) and the resin foam sheet (B) does not become too large, and the resin sheet (A) is a resin foam It becomes possible to peel off without damaging the body sheet (B). From the same viewpoint, the arithmetic mean surface roughness Ra is more preferably 0.4 μm or less, and still more preferably 0.3 μm or less.
The lower limit value of the arithmetic average surface roughness Ra of the resin sheet (A) is not particularly limited, but may be 0.01 μm or more or 0.05 μm or more from the viewpoint of availability etc. .
In addition, arithmetic mean surface roughness Ra in this specification is a value based on JISB0601 (2001), and can be calculated | required by the method as described in an Example.

(Dimension of resin sheet (A))
The thickness of the resin sheet (A) is not particularly limited, but it is preferably 10 to 500 μm from the viewpoint of effectively functioning as a reinforcing material for the resin foam sheet (B) and improving handleability and processability. -200 micrometers is more preferable, and 15-100 micrometers is still more preferable.

The resin constituting the resin sheet (A) is a polyester resin such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN); high density polyethylene (HDPE), low density polyethylene (LDPE), Linear resins such as low density polyethylene (LLDPE), polyolefin resins such as polypropylene (PP); polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene / vinyl acetate copolymer, ethylene / vinyl alcohol copolymer, etc. Acrylic resins such as vinyl resins; methyl poly (meth) acrylate and ethyl poly (meth) acrylate; styrene resins such as polystyrene; and polyamide resins such as nylon 6, nylon 66 and the like. One of these resins may be used alone, or two or more thereof may be used in combination. Also, these polymers may be homopolymers or copolymers into which a plurality of copolymerized units are introduced.
Among these, from the viewpoint of handleability and versatility, one or more selected from polyester resins, polyolefin resins and polyamide resins is preferable, and one or more selected from polyethylene, polypropylene, polyethylene terephthalate and polyamide is more preferable, and polypropylene is preferable. More preferable.

  The polypropylene may be a propylene homopolymer or a copolymer, but in the case of a copolymer, the copolymerization ratio of propylene units is preferably 50 mol% or more, more preferably 70 mol% or more, 90 mol% or more is more preferable, and 95 mol% or more is still more preferable. Examples of copolymerizable monomers include α-olefins, acrylic esters, and vinyl acetate. One of these monomers may be used alone, or two or more of these monomers may be used in combination.

The resin sheet (A) preferably contains the above-described resin as a main component, and the content thereof is preferably 60% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass or more. In addition, the main component in this specification means the component with most content rate.
The resin sheet (A) may contain, as necessary, additives such as an antioxidant, a heat stabilizer, a colorant, a flame retardant, an antistatic agent, and a filler, in addition to the above-described resin. .

The resin sheet (A) may be stretched at least uniaxially in the MD direction and the TD direction, or may be biaxially stretched.
Examples of the biaxially stretched resin sheet (A) include a biaxially stretched polypropylene (OPP) sheet, a biaxially stretched polyethylene terephthalate sheet, and a biaxially stretched polyamide sheet.

<Resin foam sheet (B)>
The resin foam sheet (B) is laminated on the resin sheet (A), and is preferably provided directly on the surface of the resin sheet (A).
(Arithmetic mean surface roughness Ra)
The arithmetic mean surface roughness Ra of the surface of the resin foam sheet (B) on the side facing the resin sheet (A) is preferably 1.0 to 15.0 μm. By making said arithmetic mean surface roughness Ra into 1.0 micrometer or more, the area which receives the pressurization at the time of adhesion becomes small, and by making load concentrate, resin sheet (A) and resin foam sheet (B) The resin sheet (A) can reinforce the mechanical strength of the resin foam sheet (B) having weak mechanical strength, and can improve its handleability and processability. On the other hand, by setting said arithmetic mean surface roughness Ra to 15.0 micrometers or less, the adhesion area of a resin sheet (A) and a resin foam sheet (B) is ensured, and appropriate adhesiveness is acquired. From these viewpoints, the arithmetic mean surface roughness Ra is more preferably 2.0 to 10.0 μm, and still more preferably 2.0 to 8.0 μm. In the foamed sheet, the surface roughness Ra can be adjusted depending on the degree of foaming, the degree of crosslinking at the time of foaming, the presence or absence of surface treatment, the type, etc. For example, the apparent density and the degree of crosslinking are adjusted to the desired ranges described later This makes it easy to adjust the surface roughness Ra within the above range.

(Dimensions of resin foam sheet (B))
The thickness of the resin foam sheet (B) is preferably 0.05 to 3.0 mm. By setting the thickness to 0.05 mm or more, securing of the mechanical strength and flexibility of the resin foam sheet (B) is facilitated. On the other hand, by setting the thickness to 3.0 mm or less, thin film formation becomes possible, and the film can be suitably used for miniaturized electronic devices. From these viewpoints, the thickness of the resin foam sheet (B) is more preferably 0.05 to 2.0 mm, and still more preferably 0.05 to 1.5 mm. When the thickness of the resin foam sheet (B) is, for example, 0.2 mm or more, when the resin sheet (A) is peeled off, the resin foam sheet (B) is hardly stretched.

(Apparent density)
The apparent density of the resin foam sheet (B) is preferably 0.05 to 0.75 g / cm ³ . By setting the apparent density to 0.05 g / cm ³ or more, mechanical strength is enhanced, and durability can be further improved. On the other hand, by setting the apparent density to 0.75 g / cm ³ or less, the compressive strength and the flexibility become good, and the impact absorptivity of the resin foam sheet (B), the sealability and the like tend to be good. From these viewpoints, the apparent density of the resin foam sheet (B) is more preferably 0.07~0.70g / cm ^3, more preferably 0.10~0.60g / cm ^3.
The apparent density of the resin foam sheet (B) can be measured in accordance with JIS K 7222 (2005).

(Tensile modulus)
The tensile elastic modulus of the resin foam sheet (B) is preferably 0.5 to 50.0 MPa. By setting the tensile elastic modulus to 0.5 MPa or more, the mechanical strength becomes high, and the durability can be more easily improved. On the other hand, by setting the tensile elastic modulus to 50.0 MPa or less, the compressive strength and the flexibility become good, and the impact absorptivity and the sealability of the resin foam sheet (B) tend to be favorable. From these viewpoints, the tensile modulus is more preferably 1.0 to 45.0 MPa, and still more preferably 2.0 to 40.0 MPa.
In addition, the tensile elasticity modulus of the resin foam sheet (B) means the tensile elasticity modulus of MD direction in 23 degreeC, and it can obtain | require based on JISK7161-1 (2014).

(Crosslinking degree)
The resin foam sheet (B) is preferably crosslinked, and the degree of crosslinking is preferably 10 to 80% by mass. By setting the degree of crosslinking to 10% by mass or more, the mechanical strength becomes high, and the durability can be easily improved. On the other hand, by setting the degree of crosslinking to 80% by mass or less, the compressive strength and the flexibility become good, and the impact absorptivity and the sealability of the resin foam sheet (B) tend to be favorable. From these viewpoints, the crosslinking degree is more preferably 20 to 70% by mass, and still more preferably 25 to 65% by mass.
The degree of crosslinking can be measured by the following method.
<Method of measuring crosslinking degree>
About 100 mg of a test piece is taken from the resin foam sheet (B), and the weight A (mg) of the test piece is precisely weighed. Next, the test piece is immersed in 30 cm ³ of xylene at 120 ° C. and left for 24 hours, and then filtered through a 200 mesh wire mesh to collect insolubles on the wire net, vacuum-dried, and the weight of the insoluble portion Carefully weigh B (mg). From the obtained values, the degree of crosslinking (% by mass) is calculated by the following equation.
Degree of crosslinking (% by mass) = 100 × (B / A)

(Material of resin foam sheet (B))
As a resin used for the resin foam sheet (B), various resins may be used, and among them, it is preferable to use a polyolefin resin. By using a polyolefin resin, it is possible to ensure the flexibility of the resin foam sheet (B).

[Polyolefin resin]
As a polyolefin resin, a polyethylene resin, a polypropylene resin, an ethylene-vinyl acetate copolymer etc. are mentioned, Among these, a polyethylene resin is preferable.
The polyethylene resin may, for example, be a polyethylene resin polymerized with a polymerization catalyst such as a Ziegler-Natta compound, a metallocene compound or a chromium oxide compound, and a polyethylene resin polymerized with a polymerization catalyst of a metallocene compound is preferable.

Moreover, as a polyethylene resin, linear low density polyethylene is preferable. By using linear low density polyethylene, high flexibility can be obtained in the resulting resin foam sheet (B), and thinning of the resin foam sheet (B) can be achieved. The linear low density polyethylene is more preferably one obtained by using a polymerization catalyst such as a metallocene compound. In addition, linear low density polyethylene is obtained by copolymerizing ethylene (for example, 75% by mass or more, preferably 90% by mass or more with respect to the total amount of monomers) and, if necessary, a small amount of α-olefin. Linear low density polyethylene is more preferred.
Specific examples of the α-olefin include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene and the like. Among these, C4-C10 alpha-olefin is preferable.
Polyethylene resin, for example the density of the linear low density polyethylene as described above is preferably 0.870~0.910g / cm ^3, more preferably 0.875~0.907g / cm ^3, 0.880~0.905g / Cm ³ is more preferred. As a polyethylene resin, a plurality of polyethylene resins can also be used, and polyethylene resins other than the above-described density range may be added.

[Metallocene compounds]
As a metallocene compound, compounds, such as a bis (cyclopentadienyl) metal complex which has a structure which pinched | interposed the transition metal between the pi-electron type unsaturated compounds, are mentioned. More specifically, one or more cyclopentadienyl rings or their analogs exist as ligands (ligands) in tetravalent transition metals such as titanium, zirconium, nickel, palladium, hafnium, platinum and the like. Compounds are mentioned.
Such metallocene compounds are uniform in the nature of the active site, and each active site has the same activity. A polymer synthesized using a metallocene compound has high uniformity in molecular weight, molecular weight distribution, composition, composition distribution, etc. Therefore, when a sheet containing a polymer synthesized using a metallocene compound is crosslinked, the crosslinking becomes uniform. Proceed to

Examples of the ligand include cyclic compounds such as cyclopentadienyl ring and indenyl ring. These cyclic compounds may be substituted by a hydrocarbon group, a substituted hydrocarbon group or a hydrocarbon-substituted metalloid group. As a hydrocarbon group, a methyl group, an ethyl group, various propyl groups, various butyl groups, various amyl groups, various hexyl groups, 2-ethylhexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups, various types A cetyl group, a phenyl group etc. are mentioned. "Various" means various isomers including n-, sec-, tert- and iso-.
Also, a polymer obtained by polymerizing a cyclic compound as an oligomer may be used as a ligand.
Furthermore, in addition to unsaturated compounds of π electron system, monovalent anionic ligands or divalent anionic chelate ligands such as chlorine and bromine, hydrocarbons, alkoxides, arylamides, aryloxides, aryloxides, amides, arylamides, phosphides, aryls Phosphide or the like may be used.

As a metallocene compound containing a tetravalent transition metal, a ligand, etc., cyclopentadienyl titanium tris (dimethyl amide), methyl cyclopenta dienyl titanium tris (dimethyl amide), bis (cyclopentadienyl) titanium dichloride, dimethyl silyl Examples include tetramethylcyclopentadienyl-t-butylamidozirconium dichloride and the like.
The metallocene compound acts as a catalyst in the polymerization of various olefins in combination with a specific co-catalyst (co-catalyst). Specific examples of the cocatalyst include methylaluminoxane (MAO) and boron compounds. The molar ratio of the cocatalyst to the metallocene compound is preferably 10 to 1,000,000 mol, and more preferably 50 to 5,000 mol.
As the polyolefin resin contained in the resin foam sheet (B), when the above linear low density polyethylene is used, the above linear low density polyethylene may be used alone, but with other polyolefin resins It may be used in combination, for example, in combination with other polyolefin resins described below. When it contains other polyolefin resin, 40 mass% or less is preferable, as for the ratio of the other polyolefin resin with respect to linear low density polyethylene (100 mass%), 30 mass% or less is more preferable, and 20 mass% or less is further preferable.

As an ethylene-vinyl acetate copolymer used as polyolefin resin, the ethylene-vinyl acetate copolymer which contains 50 mass% or more of ethylene is mentioned, for example.
Moreover, as a polypropylene resin, a polypropylene, a propylene-alpha-olefin copolymer which contains 50 mass% or more of propylene, etc. are mentioned. One of these may be used alone, or two or more may be used in combination.
Specific examples of the α-olefin constituting the propylene-α-olefin copolymer include ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1- An octene etc. are mentioned. Among these, C6-C12 alpha-olefin is preferable.

When using polyolefin resin as resin, although polyolefin resin may be used independently, resin other than polyolefin resin may be included. In the resin foam sheet (B), 60 mass% or more is preferable, as for the ratio with respect to resin whole quantity of polyolefin resin, 70 mass% or more is more preferable, and 80 mass% or more is still more preferable.
Moreover, as resin other than polyolefin resin used for a resin foam sheet (B), various elastomers, such as a styrene-type thermoplastic elastomer and EPDM, are mentioned.

(Pyrolytic foam)
The resin foam sheet (B) is preferably formed by foaming a foamable composition containing the above-mentioned resin and a thermal decomposition-type foaming agent.
As a thermal decomposition type foaming agent, an organic foaming agent and an inorganic foaming agent can be used. As an organic foaming agent, azo compounds such as azodicarbonamide, metal salts of azodicarboxylic acid (such as barium azodicarboxylate), azobisisobutyronitrile and the like; nitroso compounds such as N, N'-dinitrosopentamethylenetetramine and the like; Hydrazine derivatives such as zodicarbonamide, 4,4'-oxybis (benzenesulfonyl hydrazide), toluene sulfonyl hydrazide; semicarbazide compounds such as toluene sulfonyl semicarbazide etc. may be mentioned.
Examples of the inorganic foaming agent include ammonium acid, sodium carbonate, ammonium hydrogencarbonate, sodium hydrogencarbonate, ammonium nitrite, sodium borohydride, anhydrous monosodium citrate and the like.
Among these, an azo compound is preferable, and azodicarbonamide is more preferable, from the viewpoint of obtaining fine bubbles, and from the viewpoint of economy and safety.
The thermal decomposition-type foaming agents may be used alone or in combination of two or more.
The blending amount of the thermal decomposition-type foaming agent in the foamable composition is preferably 1 to 10 parts by mass, more preferably 1 to 8 parts by mass, and still more preferably 1.5 to 7 parts by mass with respect to 100 parts by mass of the resin. .

In addition to the resin and the thermal decomposition type foaming agent, the foamable composition preferably contains a cell nucleus modifier. Examples of the cell nucleus modifier include zinc compounds such as zinc oxide and zinc stearate, and organic compounds such as citric acid and urea. Among these, zinc oxide is preferable. By using the cell nucleus adjusting agent in addition to the above-described small particle size foaming agent, the cell diameter can be easily reduced. 0.4-8 mass parts is preferable with respect to 100 mass parts of resin, 0.5-5 mass parts is more preferable, and, as for the compounding quantity of a cell nucleus regulator, 0.8-2.5 mass parts is still more preferable. .
The foamable composition optionally contains, in addition to the above, additives generally used for foams such as an antioxidant, a heat stabilizer, a colorant, a flame retardant, an antistatic agent, and a filler. It may be done.

(Method for producing resin foam sheet (B))
Although the manufacturing method of a resin foam sheet (B) does not have a restriction | limiting in particular, For example, it manufactures by heating a foamable composition containing resin and a thermal decomposition-type foaming agent, and foaming a thermal decomposition-type foaming agent. More specifically, the manufacturing method includes the following steps (1) to (3).
Step (1): A step of forming a foamable composition by mixing a resin and an additive containing a thermal decomposition-type foaming agent to obtain a foamable composition, and forming the foamable composition into a sheet (step 2): Sheet-like foaming Process of irradiating the ionizable radiation with the ionizable radiation to crosslink the foamable composition step (3): heating the crosslinked foamable composition to foam the thermal decomposition-type foaming agent to form cells

Although the method to shape | mold a sheet-like foamable composition in a process (1) is not specifically limited, For example, resin and an additive are supplied to an extruder, melt-kneaded, and a sheet of a foamable composition from an extruder It may be molded by extruding in the form of
As a method of crosslinking the foamable composition in the step (2), a method of irradiating the foamable composition with ionizing radiation such as electron beam, α ray, β ray, γ ray and the like is used. The irradiation dose of the ionizing radiation may be adjusted so that the degree of crosslinking of the resulting foam sheet falls within the above-described desired range, but 3 to 15 Mrad is preferable, and 4 to 13 Mrad is more preferable.
In the step (3), the heating temperature when heating the foamable composition to foam the thermal decomposition-type foaming agent may be at least the foaming temperature of the thermal decomposition-type foaming agent, but the foaming temperature is preferably +20 to 100 ° C. And foaming temperature + 30-70 ° C is more preferred.
Moreover, after forming a bubble, you may extend | stretch in one or both directions of MD direction or TD direction.

  However, the present manufacturing method is not limited to the above, and the resin foam sheet (B) may be obtained by a method other than the above. For example, instead of irradiating ionizing radiation, crosslinking may be carried out by a method in which an organic peroxide is blended in advance with the foamable composition and the foamable composition is heated to decompose the organic peroxide. Good.

[Structure of laminate]
The laminate of the present invention can be produced by laminating the resin sheet (A) and the resin foam sheet (B) as described above, whereby the resin sheet can be used without using an adhesive or the like. (A) and the resin foam sheet (B) have both good adhesion and releasability. Therefore, the laminate of the present invention has an adhesive application layer between the resin sheet (A) and the resin foam sheet (B) from the viewpoint of keeping the surface characteristics of the resin foam sheet (B) good. It is preferable that the resin foam sheet (B) be directly provided on the resin sheet (A) as described above.
In the present specification, the pressure-sensitive adhesive application layer is a polymer layer having so-called pressure-sensitive adhesiveness obtained by an application process such as gravure coating, and, for example, acrylic pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives, vinyl alkyl ether-based The adhesive includes silicone adhesive, polyester adhesive, polyamide adhesive, polyurethane adhesive, fluorine adhesive, epoxy adhesive, polyethylene wax and the like. These generally contain low molecular weight components derived from tackifying resins such as main component polymers or rosin derivative resins, polyterpene resins, petroleum resins, oil-soluble phenolic resins, etc. when compared to molded sheets such as resin sheets (A) In many cases, the low molecular weight component remains at the adherend interface after peeling, and the surface properties may be impaired.

The surface of the resin sheet (A) constituting the laminate of the present invention on the side facing the resin foam sheet (B), and the surface on the side of the resin foam sheet (B) facing the resin sheet (A) It may be processed. As a method of surface treatment, corona treatment, plasma discharge treatment, ozone, ultraviolet irradiation treatment and the like can be mentioned, and among these, corona treatment is preferable.
The conditions for the corona treatment may be appropriately adjusted so that the 180 ° peel strength of the resin sheet (A) with the resin foam sheet (B) falls within the above range, for example, the temperature 23 ° C. and the humidity 60% RH Under the atmosphere, the corona treatment density can be 0.01 to 4.0 kW · min / m ² .
The laminate of the present invention is at least one of the surface of the resin sheet (A) facing the resin foam sheet (B) and the surface of the resin foam sheet (B) facing the resin sheet (A). Preferably, one of the surfaces is corona-treated, and more preferably, one of the surfaces is corona-treated. By this, the adhesiveness for making a support function effectively as a reinforcing material at the time of processing, and the releasability which can peel a support easily easily after processing can be made to be highly compatible.

[Method of manufacturing laminate]
Although the manufacturing method of the laminated body of this invention is not specifically limited, It is preferable to bond and manufacture a resin sheet (A) and a resin foam sheet (B).
Bonding of the resin sheet (A) and the resin foam sheet (B) is preferably performed under pressure. Although pressurization can be performed using a roll press, a flat plate press, etc., it is preferable to bond together by a roll press from a viewpoint of productivity. The pressure bonding pressure at the time of pressurization may be appropriately determined according to the material of the support and the like, but can be, for example, in the range of 0.5 to 3.0 MPa. Moreover, you may heat at the time of pressurization, and heating temperature can be made into the range of 30-70 degreeC, for example.

[Uses of laminates, etc.]
The laminate of the present invention is usually processed and the like, and then the resin sheet (A) is peeled off from the resin foam sheet (B).
Although the use of the resin foam sheet (B) with which the laminated body of this invention is equipped is not specifically limited, For example, it is preferable to use inside electronic devices. Since the laminate of the present invention is excellent in handleability, it can be suitably used particularly in various portable electronic devices in which the space for arranging the resin foam sheet (B) is small. The portable electronic device includes a mobile phone, a camera, a game device, an electronic notebook, a personal computer and the like. Moreover, the resin foam sheet (B) with which the laminated body of this invention is equipped can be used as an impact-absorbing material and a sealing material inside electronic devices, and you may use it for an adhesive tape.

  The present invention will be described in more detail by way of examples, but the present invention is not limited by these examples.

[Measuring method]
The measuring method and evaluation method of each physical property are as follows.

<180 ° peel strength>
The laminate obtained in each example was cut into a length of 25 mm × 200 mm, and then the foam surface was bonded to a polycarbonate plate using a double-sided adhesive tape using PET as a base material, to obtain a measurement sample.
Among the fixed laminates, one end of the resin film (A) was peeled off by 30 mm, and fixed to a chuck of a tensile tester ("Tensilon universal material tester" manufactured by A & D Co., Ltd.). Thereafter, the resin sheet (A) was pulled by 50 mm or more at a peeling angle of 180 ° and a speed of 300 mm / min, and the section average value of the load (N) detected by the load cell was recorded.

<Damage of resin foam sheet (B) at peeling off>
After the 180 ° peel strength test, the surface of the resin foam sheet (B) after peeling the resin sheet (A) is visually observed in the range of 25 × 100 mm, and the resin at the time of peeling based on the following criteria Damage to the foam sheet (B) was evaluated.
A: The resin foam sheet (B) was not damaged.
B: Roughening occurred on the surface of the resin foam sheet (B).
C: The surface of the resin foam sheet (B) was roughened, and elongation was also generated.
D: Peeling did not occur at the interface between the resin sheet (A) and the resin foam sheet (B), and the resin foam sheet (B) was broken.

<Apparent density>
The apparent density of the resin foam sheet was measured in accordance with JIS K7222 (2005).

<Tensile modulus>
The tensile modulus of elasticity of the resin foam sheet was determined in the MD direction at 23 ° C. in accordance with JIS K 7222 (2005).

<Surface tension>
The surface tension of the resin film (A) was measured in accordance with JIS K6768 (1999).

Arithmetic Average Surface Roughness Ra (μm)
Photographing the surface of the resin sheet (A) and the resin foam sheet (B) at a magnification of 10 times using a laser microscope "VK-X100" manufactured by Keyence Corporation, and using the attached analysis application The analysis was done. A measurement line of 1 mm in length was set at an arbitrary position on the photographed screen, and a line roughness curve of that portion was measured. Next, the obtained curve was analyzed under the conditions shown below to calculate the arithmetic mean surface roughness Ra at any position. Furthermore, the same measurement was performed at three arbitrary places of the resin foam sheet, and the average value was taken as the arithmetic average surface roughness Ra.
<Analysis condition>
・ Light amount smoothing: None ・ Height smoothing: ± 12 simple average ・ Inclination correction: None ・ Cutoff by phase compensation type reduction filter: λs 25 μm, λ c no

Example 1
A resin sheet comprising a long foamable composition which is supplied with a resin, a thermal decomposition type foaming agent, a cell core regulator and an antioxidant according to the composition shown in Table 1 and is melt-kneaded at 130 ° C. Extruded.
Next, 5.0 Mrad of electron beam with an accelerating voltage of 500 kV is irradiated on both sides of the above long resin sheet to crosslink the resin sheet, and then the cross-linked resin sheet is foamed maintained at 250 ° C. by hot air and infrared heater. The mixture was continuously fed into a furnace, heated and foamed to obtain a foamed sheet having a thickness of 300 μm. The obtained resin foam sheet was subjected to a corona treatment for the purpose of improving the adhesion with the resin sheet as a support. The corona treatment is performed by using a high frequency power supply "AGF-B20" manufactured by Kasuga Denki Co., Ltd. and a wire type electrode, under an atmosphere of temperature 23 ° C. and humidity 60% RH, corona treatment density 1.0 kW · min / It was carried out under the conditions of m ^2.
Then, using a roll press, the resin foam sheet obtained above and a 20 μm-thick biaxially oriented polypropylene (OPP) sheet shown in Table 1 have a temperature of 30 ° C. and a pressure bonding pressure of 1.0 MPa. Under pressure, the laminate was bonded to obtain a laminate.

[Examples 2 to 13, Comparative Example 3, Comparative Example 4]
A laminate was obtained in the same manner as in Example 1 except that the resin sheet (A) and the resin foam sheet (B) were changed to those shown in Table 1 in Example 1.

Comparative Example 1
"PORON SR-S-40P (brand name)" (made by Roger Sui Noac Co., Ltd.) which is a commercial item of a layered product provided with a resin foam sheet and a resin film was used.

Comparative Example 2
A laminate was obtained in the same manner as in Example 2 except that the resin foam sheet was changed to a bulk sheet produced by the method shown below in Example 2.
<Production of bulk sheet>
In the method for producing a resin foam sheet of Example 1, one prepared by the same method as Example 1 except that the thermal decomposition type foaming agent and the cell nucleus adjusting agent were not added and was not introduced into the foaming furnace. As a bulk sheet.

  The evaluation results of the laminate obtained in each of the above examples are shown in Table 1. In the table, "-" means not measured or unknown.

(* 1)
-OPP: biaxially oriented polypropylene sheet (Futamura Chemical Co., Ltd., trade name: FOA)
PET-1: biaxially stretched polyethylene terephthalate sheet (Toyobo Co., Ltd., trade name: E3120-12)
-PET-2: biaxially stretched polyethylene terephthalate sheet (manufactured by UNITICA CORPORATION, trade name: PTHA-25)
・ LL: Linear low density polyethylene sheet (Toyobo Co., Ltd., trade name: SE620L)
・ CPP: Axle-oriented polypropylene sheet (made by Toyobo Co., Ltd., trade name: P1128)
(* 2) Linear low density polyethylene resin (LLDPE) (manufactured by Exxon Chemical Co., Ltd., trade name “EXACT3027”, density: 0.900 g / cm ³ )
(* 3) azodicarbonamide (* 4) zinc oxide

  From Table 1, the laminate of Examples 1 to 13 in which the 180 ° peel strength between the resin sheet (A) and the resin foam sheet (B) is 0.02 to 0.50 N / 25 mm is the resin sheet (A) It can be seen that while the resin foam sheet (B) has adequate adhesion, it can be peeled off without damaging the resin foam sheet (B). On the other hand, in the laminate of Comparative Example 1 in which the 180 ° peel strength exceeds 0.50 N / 25 mm, the resin sheet (A) could not be peeled from the resin foam sheet (B). In addition, the laminates of Comparative Examples 2 to 4 in which the 180 ° peel strength is less than 0.02 N / 25 mm maintain the laminated form of the resin sheet (A) and the resin foam sheet (B) because the peel strength is too low. I could not.

Claims (10)

  It is a laminated body formed by laminating a resin sheet (A) and a resin foam sheet (B), and the 180 ° peel strength of the resin sheet (A) and the resin foam sheet (B) is 0.02 to A laminate that is 0.50 N / 25 mm.   The laminate according to claim 1, wherein the resin sheet (A) contains as a main component one or more selected from polyethylene, polypropylene, polyethylene terephthalate and polyamide.   The laminated body of Claim 1 or 2 whose arithmetic mean surface roughness Ra of the surface of the side which opposes the resin foam sheet (B) of a resin sheet (A) is 0.5 micrometer or less.   The laminated body of any one of Claims 1-3 which does not have an adhesion application layer between a resin sheet (A) and a resin foam sheet (B).   The laminate according to any one of claims 1 to 4, wherein the resin foam sheet (B) is mainly composed of linear polyethylene polymerized using a metallocene catalyst.   The arithmetic average surface roughness Ra of the surface on the side facing the resin sheet (A) of the resin foam sheet (B) is 1.0 to 15.0 μm, according to any one of claims 1 to 5. Stacks. The laminated body of any one of Claims 1-6 whose apparent density of a resin foam sheet (B) is 0.05-0.75 g / cm < ³ >.   The laminated body of any one of Claims 1-7 whose thickness of a resin foam sheet (B) is 0.05-3.0 mm.   The laminated body of any one of Claims 1-8 whose tensile elasticity modulus of a resin foam sheet (B) is 0.5-50.0 Mpa.   At least one of the surface of the resin sheet (A) on the side facing the resin foam sheet (B) and the surface on the side of the resin foam sheet (B) facing the resin sheet (A) have a corona The laminated body of any one of Claims 1-9 which is processed.