JP2013071320A - Moisture-permeable foamed multilayer sheet and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foamed multilayer sheet having both of moisture permeability and contamination resistance (particularly in a venthole portion).SOLUTION: The foamed multilayer sheet is obtained by layering a foamed resin layer, which is formed by a melt-molding method, and a surface protective layer in this order on a base material. Ventholes, each of which penetrates the surface protective layer and the foamed resin layer at the least, are formed on the foamed multilayer sheet, so that the foamed multilayer sheet has contamination resistance while ensuring moisture permeability.

Description

  The present invention relates to a foamed laminated sheet having both moisture permeability and contamination resistance. Moreover, this invention relates to the laminated sheet used for manufacture of the said foaming laminated sheet. Furthermore, this invention relates to the manufacturing method of the said foaming lamination sheet and a lamination sheet.

  In recent years, the demand for comfort in the living environment has been enumerated, and in the field of architectural interiors, as a decorative sheet used for wallpaper, the stain resistance, scratch resistance, durability, Various foamed laminated sheets with cracking properties and the like have been developed. For example, Patent Document 1 reports a wallpaper in which a coating layer composed of a foaming agent, an aqueous emulsion resin and other additives is provided on a base material, and a foamed resin film having a stain resistance is further pasted. Yes. The foam laminated sheet provided with a surface protective layer and a foamed resin layer made of a resin film or the like as in Patent Document 1 can have characteristics such as surface strength, chemical resistance, solvent resistance, and contamination resistance, There exists a fault that moisture permeability is impaired by the said surface protective layer. The wallpaper having low moisture permeability has a problem of causing condensation depending on the room humidity. Furthermore, the wallpaper having low moisture permeability also has a problem that the construction paste is difficult to dry at the time of wallpaper construction.

  On the other hand, it is conventionally known that moisture permeability can be ensured by providing a through hole (vent hole) in a film or sheet. In the field of wallpaper, it is also known that by providing a through-hole in a foamed laminated sheet, not only moisture permeability but also peel-up property can be imparted and air puncture can be prevented (for example, Patent Documents 2-4) reference). However, the foamed laminated sheet having through-holes has a drawback in that contaminants easily enter the sheet through the through-holes, and the stain resistance is reduced. In particular, when a through-hole is provided in a laminated foam sheet having a surface protective layer and a foamed resin layer, a contaminant penetrates into the interface between the foamed resin layer and the surface protective layer, which spreads and deteriorates the contamination. There is a problem that once a contaminant is mixed in, it becomes difficult to remove the contaminant.

  In recent years, as the number of houses with high airtightness has increased, a foamed laminated sheet having both moisture permeability and contamination resistance is required, but a foamed laminated sheet having both of these characteristics has not been developed. Is the current situation.

JP-A-8-309903 JP-A-4-246537 Japanese Patent Publication No. 60-25262 Japanese Patent Publication No. 60-39544

  The present invention provides a foamed laminated sheet having moisture permeability and contamination resistance (especially, contamination resistance in a vent hole portion), a laminated sheet used for the production of the foamed laminated sheet, and a method for producing these. Objective.

  The inventors of the present invention made extensive studies to solve the above problems, and in the laminated foamed sheet in which the foamed resin layer formed by melt molding and the surface protective layer were sequentially laminated on the base material, at least the It has been found that by providing a vent hole penetrating the surface protective layer and the foamed resin layer, the vent hole can ensure moisture permeability and also have stain resistance in the vent hole portion. The present invention has been completed by further studies based on such knowledge.

That is, this invention provides the foaming lamination sheet of the aspect hung up below, a lamination sheet, and these manufacturing methods.
Item 1. A foamed resin layer formed by melt molding and a surface protective layer are sequentially laminated on a base material, and has at least a vent hole penetrating the surface protective layer and the foamed resin layer. A foamed laminated sheet.
Item 2. Item 2. The foamed laminated sheet according to Item 1, wherein an average pore diameter of the vent holes on the surface of the surface protective layer is 50 to 300 µm.
Item 3. Item 3. The foamed laminated sheet according to Item 1 or 2, wherein the surface protective layer contains a thermoplastic resin.
Item 4. Item 4. The foamed laminated sheet according to any one of Items 1 to 3, wherein the foamed resin layer is crosslinked.
Item 5. Item 5. The foamed laminated sheet according to any one of Items 1 to 4, further comprising a non-foamed resin layer between the base material and the foamed resin layer and / or between the foamed resin layer and the surface protective layer.
Item 6. On the base material, a foaming agent-containing resin layer formed by melt molding and a surface protective layer are sequentially laminated, and at least have a vent hole penetrating the surface protective layer and the foaming agent-containing resin layer. A laminated sheet characterized by that.
Item 7. A method for producing a foamed laminated sheet having air holes,
A first step of forming a foaming agent-containing resin layer on the substrate by melt molding;
A second step of forming a surface protective layer on the foaming agent-containing resin layer, and a third step of foaming the foaming agent-containing resin layer to form a foamed resin layer,
And after the said 2nd process or the 3rd process, the manufacturing method of the foaming laminated sheet characterized by including the drilling process which forms the vent hole which penetrates at least the said surface protective layer and the said foamed resin layer.
Item 8. Item 8. The method for producing a foamed laminated sheet according to Item 7, wherein a crosslinking treatment is performed on the foaming agent-containing resin layer after the first step or the second step.
Item 9. A method for producing a laminated sheet having air holes,
A first step of forming a foaming agent-containing resin layer on the substrate by melt molding;
It includes a second step of forming a surface protective layer on the foaming agent-containing resin layer, and a drilling step of forming a vent hole penetrating at least the surface protective layer and the foaming agent-containing resin layer. The manufacturing method of a foam lamination sheet.
Item 10. Item 10. The method for producing a foamed laminated sheet according to Item 9, wherein a crosslinking treatment is performed on the foaming agent-containing resin layer after the first step or the second step.

  Since the foamed laminated sheet of the present invention has excellent moisture permeability, it is possible to suppress the occurrence of dew condensation even when the indoor humidity is high, and it is also possible to make it easier to dry the construction paste during wallpaper construction. Yes. In addition, the foamed laminated sheet of the present invention has good peelability when the glued surfaces are brought into close contact with each other during wallpaper construction, and is also good in terms of ease of construction. Furthermore, the foamed laminated sheet of the present invention can suppress contamination from entering the interface between the surface protective layer and the foamed resin layer through the vents, and has excellent stain resistance. Yes.

  In addition, the laminated sheet of the present invention can be produced by the simple method of foaming the foaming agent-containing resin layer contained therein, and the raw material for producing the foamed laminated sheet (raw fabric) Can be used as

  In the present specification, the “foamed laminated sheet” means a foamed sheet having a foamed resin layer, and the “laminated sheet” means a state before foaming of the foamed laminated sheet, which means a so-called unfoamed raw fabric. .

1. Foamed laminated sheet In the foamed laminated sheet of the present invention, a foamed resin layer formed by melt molding and a surface protective layer are sequentially laminated on a substrate, and at least penetrates the surface protective layer and the foamed resin layer. It has a vent hole. Hereinafter, the foamed laminated sheet of the present invention will be described in detail.

Laminated structure of foamed laminated sheet The foamed laminated sheet of the present invention has a laminated structure in which a foamed resin layer formed by melt molding and a surface protective layer are sequentially laminated on a substrate.

  In the foamed laminated sheet of the present invention, a non-foamed resin layer (non-foamed resin layer) is provided between the base material and the foamed resin layer as necessary for the purpose of improving the adhesive force between the base material and the foamed resin layer. B) may be formed. The top surface of the foamed resin layer (the surface on which the surface protective layer is laminated) is necessary for the purpose of clarifying the pattern when forming the pattern layer and improving the scratch resistance of the foamed resin layer. The non-foamed resin layer (non-foamed resin layer A) may be formed accordingly.

  In addition, even if a pattern layer is formed on the upper surface of the foamed resin layer (or the non-foamed resin layer A) and the lower surface of the surface protective layer for the purpose of imparting design properties to the foamed laminate sheet, Good.

  That is, in the foamed laminated sheet of the present invention, when the non-foamed resin layer B, the non-foamed resin layer A, and the pattern layer are provided, the base material / non-foamed resin layer B / foamed resin layer / non-foamed resin layer A It becomes a laminated structure in which / pattern pattern layer / surface protective layer is laminated in order.

  The surface protective layer may be provided with a concavo-convex pattern by embossing in order to impart design properties to the foamed laminated sheet of the present invention.

  Hereinafter, the composition and forming method of each layer constituting the foamed laminated sheet of the present invention will be described.

[Base material]
The substrate used in the present invention is not particularly limited, and a fibrous substrate that is usually used as wallpaper paper can be used. Further, the base material may contain a flame retardant, an inorganic agent, a dry paper strength enhancer, a wet paper strength enhancer, a colorant, a sizing agent, a fixing agent, and the like as necessary. Specific examples of the base material include wallpaper paper (pulp-based sheets sized with a sizing agent) and flame-retardant paper (pulp-based sheets treated with a flame retardant such as guanidine sulfamate or guanidine phosphate). Inorganic paper containing inorganic additives such as aluminum hydroxide and magnesium hydroxide; fine paper; thin paper; fiber mixed paper (mixed synthetic fiber with pulp) and the like.

The basis weight of the base material is not particularly limited, for example, 50 to 300 g / ^{m 2} approximately, and preferably about 50 to 120 / ^{m 2.}

[Foamed resin layer]
The foamed resin layer is formed by foaming the foaming agent-containing resin layer after forming a foaming agent-containing resin layer made of a resin composition containing a resin component and a foaming agent by melt molding. Thus, by using the foamed resin layer formed by melt molding, the foamed laminated sheet of the present invention can be provided with contamination resistance (particularly, contamination resistance at the vent hole portion).

  The resin component used in the foamed resin layer is not particularly limited. For example, 1) polyethylene, and 2) an ethylene copolymer having monomers other than ethylene and ethylene (hereinafter referred to as “ethylene copolymer”). Containing at least one of the following). The ethylene copolymer has characteristics suitable for film formation by melt molding from the viewpoint of melting point and MFR.

The polyethylene used in the present invention is not particularly limited, for example, density 0.942 g / cm ³ or more high-density polyethylene (HDPE) and density 0.93 g / cm ³ or more 0.942 g / cm ³ less than in Examples thereof include density polyethylene (MDPE), low density polyethylene (LDPE) having a density of 0.91 g / cm ³ or more and less than 0.93 g / cm ³ , and linear low density polyethylene (LLDPE). Among these, low density polyethylene is preferable.

  Examples of the ethylene copolymer used in the present invention include ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), and ethylene-methyl. Examples include acrylate copolymers (EMA), ethylene- (meth) acrylic acid copolymers (EMAA), and ethylene-α olefin copolymers. In the present specification, “(meth) acrylic acid” means acrylic acid or methacrylic acid. These ethylene copolymers may be used individually by 1 type, and may be used in combination of 2 or more type.

  In the ethylene copolymer, the ratio of monomers other than ethylene and ethylene is not particularly limited. For example, the content of monomers other than ethylene is usually 5 to 25% by mass, preferably 5 to 20% by mass. Can be mentioned. By adopting such a copolymerization ratio, the film forming property by melt molding can be further enhanced. Specifically, the copolymerization ratio (VA amount) of vinyl acetate in the ethylene-vinyl acetate copolymer is, for example, 9 to 25% by mass, preferably 9 to 20% by mass. The copolymerization ratio (MMA amount) of methyl methacrylate in the ethylene-methyl methacrylate copolymer is, for example, 5 to 25% by mass, preferably 5 to 15% by mass. The copolymerization ratio (MAA amount) of (meth) acrylic acid in the ethylene- (meth) acrylic acid copolymer is, for example, 2 to 15% by mass, preferably 5 to 11% by mass.

  The resin component used for the foamed resin layer is preferably an ethylene-vinyl acetate copolymer, an ethylene-methyl methacrylate copolymer, an ethylene- (meth) acrylic acid copolymer, and a polyethylene / ethylene-α-olefin copolymer. Examples include at least one mixture (hereinafter abbreviated as “preferred resin component”).

  When a mixture of polyethylene and ethylene-α-olefin copolymer is used as the resin component, these ratios are not particularly limited. For example, per 100 parts by mass of polyethylene and ethylene-α-olefin copolymer, ethylene- Examples of the α-olefin copolymer include 50 parts by mass or more and less than 100 parts by mass.

  Further, when the preferred resin component and another resin component are used in combination as the resin component, these ratios are not particularly limited. For example, the preferred resin component is 70 parts by mass or more per 100 parts by mass of the total amount of the resin components. The amount is less than 100 parts by mass, preferably 80 parts by mass or more and less than 100 parts by mass.

  The resin component contained in the foamed resin layer preferably has an MFR (melt flow rate) measured at 190 ° C. and a load of 21.18 N described in JIS K 6922 of 10 to 100 g / 10 minutes. When the MFR is within the above range, the foaming agent-containing resin layer can be formed in a non-foamed state with little temperature rise when it is formed by melt molding. Printing can be performed on the surface, and pattern omission can be reduced.

  It does not restrict | limit especially as a foaming agent used for a foamed resin layer, It can select from a well-known foaming agent. For example, azo type such as azodicarbonamide (ADCA) and azobisformamide; organic thermal decomposition type blowing agent such as hydrazide type such as oxybenzenesulfonyl hydrazide (OBSH) and paratoluenesulfonyl hydrazide; microcapsule type blowing agent; baking soda Inorganic foaming agents such as

  The content of the foaming agent can be appropriately set according to the type of foaming agent, the expansion ratio, and the like. From the viewpoint of the expansion ratio, it is 7 times or more, preferably about 7 to 10 times, and the foaming agent may be, for example, about 1 to 20 parts by mass with respect to 100 parts by mass of the resin component.

  In order to improve the foaming effect of the foaming agent, a foaming aid may be included in the foamed resin layer as necessary. Although it does not restrict | limit especially as a foaming adjuvant, For example, a metal oxide, a fatty-acid metal salt, etc. are mentioned. More specifically, zinc stearate, calcium stearate, magnesium stearate, zinc octylate, calcium octylate, magnesium octylate, zinc laurate, calcium laurate, magnesium laurate, zinc oxide, magnesium oxide, lauric hydrazide, Salicylic acid hydrazide, form hydrazide, acetohydrazide, propionic acid hydrazide, p-hydroxybenzoic acid hydrazide, naphthoic acid hydrazide, 3-hydroxy-2-naphthoic acid hydrazide, lauric acid hydrazide, salicylic acid hydrazide, form hydrazide, acetohydrazide, propionic acid P-hydroxybenzoic acid hydrazide, naphthoic acid hydrazide, 3-hydroxy-2-naphthoic acid hydrazide and the like. These foaming aids may be used alone or in combination of two or more. Although content of these foaming adjuvants is suitably set according to the kind of foaming adjuvant, the kind of foaming agent, content, etc., for example, 0.3-10 mass with respect to 100 mass parts of resin components About 1 part, Preferably about 1-7 mass parts is mentioned.

  The foamed resin layer may contain an inorganic filler as necessary for imparting flame retardancy, suppressing see-through, improving surface characteristics, and the like. The inorganic filler is not particularly limited, and examples thereof include calcium carbonate, aluminum hydroxide, magnesium hydroxide, antimony trioxide, zinc borate, and a molybdenum compound. These inorganic fillers may be used individually by 1 type, and may be used in combination of 2 or more type. Although content in particular of these inorganic fillers is not restrict | limited, For example, about 0-100 mass parts with respect to 100 mass parts of resin components, Preferably about 20-70 mass parts is mentioned.

  The foamed resin layer may contain a pigment as necessary. The pigment is not particularly limited and may be either an inorganic pigment or an organic pigment. Inorganic pigments include, for example, titanium oxide, zinc white, carbon black, black iron oxide, yellow iron oxide, yellow lead, molybdate orange, cadmium yellow, nickel titanium yellow, chrome titanium yellow, iron oxide (valve), and cadmium. Examples thereof include red, ultramarine blue, bitumen, cobalt blue, chromium oxide, cobalt green, aluminum powder, bronze powder, titanium mica, and zinc sulfide. Examples of organic pigments include aniline black, perylene black, azo (azo lake, insoluble azo, condensed azo), polycyclic (isoindolinone, isoindoline, quinophthalone, perinone, flavantron, anthrapyrimidine, anthraquinone, quinacridone, Perylene, diketopyrrolopyrrole, dibromoanthanthrone, dioxazine, thioindigo, phthalocyanine, indanthrone, halogenated phthalocyanine) and the like. These pigments may be used alone or in combination of two or more. Although content in particular of these pigments is not restrict | limited, For example, about 10-50 mass parts with respect to 100 mass parts of resin components, Preferably about 15-30 mass parts is mentioned.

  Furthermore, the foamed resin layer may contain additives such as an antioxidant, a cross-linking agent, and a surface treatment agent as necessary as long as the effects of the present invention are not hindered.

  The foamed resin layer may be cross-linked as necessary. The method for crosslinking the foamed resin layer is not particularly limited. For example, there is a method of previously crosslinking the foaming agent-containing resin layer before foaming by irradiating the foaming agent-containing resin layer before foaming with an electron beam. Can be mentioned. Specifically, with respect to the foaming agent-containing resin layer, the acceleration voltage is 100 to 150 kV, preferably 100 to 140 kV, the irradiation amount is set to 2 to 200 kGy, preferably 2.5 to 100 kGy, and the electron beam irradiation is performed. The method of performing is illustrated.

  Although it does not restrict | limit especially about the thickness of a foamed resin layer, For example, 300-700 micrometers is mentioned. As thickness before foaming of a foamed resin layer (namely, thickness of a foaming agent containing resin layer), 40-100 micrometers is mentioned, for example.

  As long as the foamed resin layer is formed on the substrate by melt molding, the formation method is not particularly limited, and examples thereof include a method of extrusion forming with a T-die extruder and a method of forming by a calendar method. A method of extrusion forming with a T-die extruder is preferred.

  The foamed resin layer is formed by melt molding a foaming agent-containing resin layer comprising a resin composition containing a resin component, a foaming agent, and other additives as required, and then foaming the foaming agent-containing resin layer. It is formed by.

[Non-foamed resin layer B (adhesive resin layer)]
The non-foamed resin layer B is an adhesive resin layer formed between the base material and the foamed resin layer as necessary for the purpose of improving the adhesive force between the base material and the foamed resin layer.

  The resin component of the non-foamed resin layer B is not particularly limited, but an ethylene-vinyl acetate copolymer (EVA) is preferable. EVA can be a known or commercially available one. In the EVA used for the non-foamed resin layer B, the ratio of the vinyl acetate component (VA component) is not particularly limited, but may be, for example, 10 to 46 mass%, preferably 15 to 41 mass%.

  Although it does not restrict | limit especially about the thickness of the non-foaming resin layer B, For example, 3-50 micrometers, Preferably about 3-20 micrometers is mentioned.

  The method for forming the non-foamed resin layer B is not particularly limited, but preferably includes a method of forming by melt molding, more preferably a method of forming by extrusion using a T-die extruder. In particular, it is desirable to form the foamed resin layer and the non-foamed resin layer B by coextrusion using a multi-manifold type T die that can simultaneously form two or more layers by extruding the molten resin simultaneously.

[Non-foamed resin layer A]
The non-foamed resin layer A is a layer formed on the upper surface of the foamed resin layer as necessary for the purpose of clarifying the pattern when forming the pattern layer or improving the scratch resistance of the foamed resin layer. It is.

  The resin component of the non-foamed resin layer A is not particularly limited, and examples thereof include polyolefin resins, methacrylic resins, thermoplastic polyester resins, polyvinyl alcohol resins, and fluorine resins. These resin components may be used individually by 1 type, and may be used in combination of 2 or more type. Among these resin components, a polyolefin resin is preferable.

  Specific examples of polyolefin resins include polyethylene, polypropylene, polybutene, polybutadiene, polyisoprene, and other resins, copolymers of α-olefins having 4 or more carbon atoms (linear low density polyethylene), and ethylene-acrylic acid. Examples thereof include a methyl copolymer, an ethylene-ethyl acrylate copolymer, an ethylene- (meth) acrylic acid copolymer, an ethylene-vinyl acetate copolymer, a saponified ethylene-vinyl acetate copolymer, and an ionomer.

  Although it does not restrict | limit especially about the thickness of the non-foaming resin layer A, For example, 3-50 micrometers, Preferably about 3-20 micrometers is mentioned.

  The method for forming the non-foamed resin layer A is not particularly limited, but preferably includes a method of forming by melt molding, and more preferably a method of forming by extrusion with a T-die extruder. In particular, it is desirable to form the foamed resin layer and the non-foamed resin layer B by coextrusion using a multi-manifold type T die. When three layers of the non-foamed resin layer A, the foamed resin layer, and the non-foamed resin layer B are provided, these three layers are formed using a multi-manifold type T-die capable of forming three layers simultaneously. It is desirable to form by coextrusion.

[Pattern pattern layer]
The pattern layer is a layer formed on the top surface of the foamed resin layer (or non-foamed resin layer A) as necessary for the purpose of imparting design properties to the foamed laminate sheet.

  Examples of the design pattern include a wood grain pattern, a stone pattern, a grain pattern, a tiled pattern, a brickwork pattern, a cloth pattern, a leather pattern, a geometric figure, a character, a symbol, and an abstract pattern. A design pattern can be suitably selected according to the use of a foaming lamination sheet.

  The pattern pattern layer can be formed, for example, by printing a pattern pattern. Examples of printing methods include gravure printing, flexographic printing, silk screen printing, offset printing, and the like. As the printing ink, a printing ink containing a colorant, a binder resin, a solvent (or a dispersion medium), and the like can be used. These inks may be known or commercially available.

  Although it does not restrict | limit especially as a coloring agent, For example, the pigment used with the said foamed resin layer can be used suitably.

  The binder resin may be set as appropriate according to the type of the base sheet. For example, acrylic resin, styrene resin, polyester resin, urethane resin, chlorinated polyolefin resin, vinyl chloride-vinyl acetate. Examples include copolymer resins, polyvinyl butyral resins, alkyd resins, petroleum resins, ketone resins, epoxy resins, melamine resins, fluorine resins, silicone resins, fiber derivatives, rubber resins, and the like. These binder resins may be used alone or in combination of two or more.

  Although it does not restrict | limit especially as a solvent (or dispersion medium), For example, petroleum-type organic solvents, such as hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane, methylcyclohexane; Ethyl acetate, butyl acetate, 2-methoxyacetate Ester-based organic solvents such as ethyl and 2-ethoxyethyl acetate; alcohol-based organic solvents such as methyl alcohol, ethyl alcohol, normal propyl alcohol, isopropyl alcohol, isobutyl alcohol, ethylene glycol, propylene glycol; acetone, methyl ethyl ketone, methyl isobutyl ketone Ketone organic solvents such as cyclohexanone; ether organic solvents such as diethyl ether, dioxane and tetrahydrofuran; dichloromethane, carbon tetrachloride, trichloroethylene, Chlorinated organic solvents such as tiger chloroethylene; and water. These solvents (or dispersion media) may be used individually by 1 type, and may be used in combination of 2 or more type.

  The thickness of the design pattern layer is appropriately set according to the type of design pattern and the like, and may be about 0.1 to 10 μm, for example.

[Surface protective layer]
A surface protective layer is formed on the top surface of the foamed resin layer (or the non-foamed resin layer A or the pattern layer). In order to further improve the adhesion of the surface protective layer, the surface protection is performed after easy adhesion treatment (primer treatment) on the surface of the foamed resin layer (or non-foamed resin layer A or pattern layer) on which the surface protective layer is laminated. Layers can also be provided.

  The material for the surface protective layer is not particularly limited, and a known resin can be used. For example, the surface protective layer may be a layer formed of a thermoplastic resin (hereinafter abbreviated as a thermoplastic resin layer), or a layer formed by curing a curable resin (hereinafter, a cured resin). (Abbreviated as layer). In particular, when vents are provided in a foamed laminate sheet made by laminating a foamed resin layer and a thermoplastic resin layer formed by a technique other than melt molding such as a coating method, the interface between the foamed resin layer and the thermoplastic resin layer is contaminated. Substances are significantly mixed, and pollutants spread in the foamed layer. In the foamed laminated sheet of the present invention, the foamed resin layer provided by such a coating method and a thermoplastic resin layer are used in combination. It is possible to solve the problems and to have excellent contamination resistance. In view of the effect of the present invention, a preferable example of the surface protective layer includes one having at least a thermoplastic resin layer.

  The surface protective layer may be a single layer or may be a laminate of two or more layers. For example, a two-layer structure in which a cured resin layer is formed on the outermost surface and a thermoplastic resin layer is laminated on the lower layer thereof may be used.

  Although it does not restrict | limit especially as thickness of a surface protective layer, For example, in the case of a thermoplastic resin layer, 5-25 micrometers normally, Preferably 10-20 micrometers is mentioned, In the case of a cured resin layer, it is 1-10 micrometers normally. Preferably, 2-5 micrometers is mentioned.

  Hereinafter, the thermoplastic resin layer and the cured resin layer will be described.

(Thermoplastic resin layer)
Although it does not restrict | limit especially as a resin component used for a thermoplastic resin layer, For example, polyolefin resin, polyvinyl alcohol resin, a fluororesin etc. are mentioned. These resin components may be used individually by 1 type, and may be used in combination of 2 or more type. Among these resin components, a polyolefin resin is preferable.

  Specific examples of the polyolefin resin include polyethylene, ethylene copolymer, polypropylene, polybutene, polybutadiene, and polyisoprene. Among these polyolefin resins, polyethylene and ethylene copolymers are preferable, and polyethylene is more preferable.

The polyethylene used in the thermoplastic resin layer is not particularly limited, for example, density 0.942 g / cm ³ or more high-density polyethylene (HDPE) and density 0.93 g / cm ³ or more 0.942 g / cm less than ³ density polyethylene (MDPE) within, such as density 0.91 g / cm ³ or more 0.93 g / cm ³ less than the low-density polyethylene (LDPE) and the like. Moreover, you may use the ultra-low density polyethylene (LLDPE) whose density is the range of 0.85-0.91 g / cm <3>. Among these polyethylenes, it is preferable to use polyethylene having a low density because curling of the foamed laminated sheet can be suppressed.

  Although it does not restrict | limit especially as an ethylene copolymer used for a thermoplastic resin layer, For example, ethylene-acrylic acid copolymer resin, ethylene-methyl acrylate copolymer resin, ethylene-ethyl acrylate copolymer resin , Ethylene (meth) acrylic acid copolymer resin such as ethylene-methacrylic acid copolymer resin, ethylene-vinyl acetate copolymer (EVA), saponified ethylene-vinyl acetate copolymer resin, ionomer and the like. . Among these polyethylenes, ethylene (meth) acrylic acid copolymer resins are preferable, and ethylene-methacrylic acid copolymer resins are more preferable.

  Further, when the thermoplastic resin layer contains a crosslinkable resin component such as polyethylene or an ethylene copolymer, the thermoplastic resin layer may be subjected to a crosslinking treatment as necessary. When the thermoplastic resin layer is cross-linked in this way, the heat resistance of the thermoplastic resin layer can be improved, and even when the thermoplastic resin layer is formed in a thin film shape, the surface falling during heating and foaming is suppressed. Therefore, it is possible to effectively prevent a decrease in contamination resistance. The method for crosslinking the thermoplastic resin layer is not particularly limited, and examples thereof include a method of irradiating the thermoplastic resin layer with an electron beam. Specifically, a method of irradiating the thermoplastic resin layer with an electron beam by setting an acceleration voltage of about 70 to 300 kV and an irradiation dose of about 5 to 250 kGy is exemplified.

  Further, the thermoplastic resin layer may contain various additives such as an ultraviolet absorber, an antioxidant, a crosslinking agent, an antistatic agent, and an antibacterial agent, depending on the desired physical properties to be provided.

  The thermoplastic resin layer may be formed by sticking a previously prepared thermoplastic resin film to the surface of the foamed resin layer (or the non-foamed resin layer A or the design pattern layer). Therefore, it is desirable to extrude and form a thermoplastic resin on the surface of the foamed resin layer (or the non-foamed resin layer A or the pattern layer).

(Cured resin layer)
Examples of the curable resin used for the curable resin layer include an ionizing radiation curable resin and a thermosetting resin (including a room temperature curable resin and a two-component reaction curable resin). Among these, an ionizing radiation curable resin is preferable because it has a high curing rate and good workability, and it is easy to adjust the physical properties of the resin such as flexibility and hardness.

  Specific examples of the ionizing radiation curable resin include those obtained by appropriately mixing a prepolymer, an oligomer, and / or a monomer having a polymerizable unsaturated bond or an epoxy group in the molecule. Here, the ionizing radiation refers to an electromagnetic wave or a charged particle beam having an energy quantum capable of polymerizing or cross-linking molecules, and usually an ultraviolet ray or an electron beam is used. The ionizing radiation curable resin is preferably one that undergoes radical polymerization (curing) by electron beam irradiation.

  The cured resin layer may contain silicone (meth) acrylate, if necessary, for the purpose of imparting surface physical properties such as contamination resistance and controlling the surface tension of the surface protective layer. The silicone (meth) acrylate is not particularly limited as long as the organic group is a methacryl group or an acryl group, and examples thereof include modified silicone oils having 1 to 6 organic groups. The structure of the modified silicone oil is roughly classified into a side chain type, a both-end type, a one-end type, and a side-chain both end type depending on the bonding position of the organic group to be substituted. Not limited. Moreover, it does not restrict | limit especially as a functional group equivalent (molecular weight / functional group number) of silicone (meth) acrylate, For example, what has the conditions of 1000-20000 is mentioned.

  Although content in particular of silicone (meth) acrylate is not restrict | limited, For example, 0.5-4 mass parts with respect to 100 mass parts of ionizing radiation-curable resins, Preferably 1.0-2.5 mass parts is mentioned. .

  The cured resin layer has a weather resistance improver, an abrasion resistance improver, a polymerization inhibitor, a crosslinking agent, an infrared absorber, an antistatic agent, an adhesion improver, and a leveling depending on the desired physical properties to be provided. Various additives such as an agent, a thixotropic agent, a coupling agent, a plasticizer, an antifoaming agent, a filler, a solvent, and a coloring agent may be included.

  The cured resin layer may be formed by a method according to the type of curable resin to be used. For example, when an ionizing radiation curable resin is used, the method can be performed by the following method: 1) Prepare an ionizing radiation curable resin composition in which an ionizing radiation curable resin and, if necessary, silicone (meth) acrylate and various additives are mixed, (2) an ionizing radiation curable resin composition, gravure coat, The foamed resin layer (or the non-foamed resin layer A or the pattern layer) is applied by a method such as bar coating, roll coating, reverse roll coating, or comma coating. (3) Ionizing radiation is irradiated to cure the ionizing radiation curable resin composition. When the ionizing radiation curable resin composition is cured, when an electron beam is used as the ionizing radiation, examples of the electron beam irradiation condition include an acceleration voltage of about 70 to 300 kV and an irradiation dose of about 5 to 250 kGy.

[Uneven pattern]
In order to impart designability to the foamed laminated sheet of the invention, the surface protective layer may be provided with an uneven pattern by embossing as necessary. Embossing can be performed by known means such as pressing of an embossed plate. The uneven pattern is not particularly limited, and examples thereof include a wood grain plate conduit groove, a stone plate surface unevenness, a cloth surface texture, a satin texture, a grain, a hairline, and a striated groove.

Structure of Vent Hole of Foamed Laminate Sheet The foamed laminate sheet of the present invention has a vent hole penetrating at least the surface protective layer and the foamed resin layer.

  The air holes provided in the foamed laminated sheet of the present invention need only penetrate the foamed resin layer from the upper surface of the surface protective layer, but from the viewpoint of providing excellent moisture permeability, the air holes are provided on the surface protective layer. It is preferable to penetrate from the upper surface to the lower surface of the substrate (the surface opposite to the surface on which the foamed resin layer is laminated).

  The cross-sectional shape of the air holes provided in the foamed laminated sheet of the present invention is not limited to a circle, and may be a polygon such as a triangle or a rectangle.

  The average pore diameter of the vent holes provided in the foamed laminated sheet of the present invention is not particularly limited, and examples thereof include an average pore diameter of 50 to 300 μm, preferably 100 to 250 μm on the surface of the surface protective layer. The said average hole diameter is a value calculated by measuring a hole diameter about ten ventilation holes provided in the foaming lamination sheet with the optical microscope, and calculating the average value.

Further, the number of ventilation holes per unit area of the foamed laminate sheet of the present invention is not particularly limited, for example, foamed laminate sheet 1 cm ² per 0.75 to 30, preferably include 1 to 25 amino .

Further, the opening area in the foamed laminated sheet of the present invention is determined according to the number of ventilation holes per unit area, the hole diameter, etc., and is not particularly limited, but from the viewpoint of further improving moisture permeability. preferably 0.04~1.5mm ² / cm ^2, more preferably 0.05~1.25mm ² / cm ^2. In addition, an opening area is a ratio of the surface area which the ventilation hole per unit surface area of a foaming lamination sheet occupies.

The formation of the air holes in the foamed laminated sheet of the present invention can be performed, for example, by a method using a CO2 laser, a method using a needle embossing device composed of a needle roll and a back roll, or the like.
2. Laminated sheet

  In the laminated sheet of the present invention, a foaming agent-containing resin layer formed by melt molding and a surface protective layer are sequentially laminated on a substrate, and at least penetrates the surface protective layer and the foaming agent-containing resin layer. It has a vent hole.

  The laminated sheet of the present invention is in a state before foaming of the foamed laminated sheet, and the foamed resin layer of the foamed laminated sheet is in a state before foaming (that is, a foaming agent-containing resin layer containing a resin component and a foaming agent). Except this, it is the same as the foamed laminated sheet.

  The laminated sheet of the present invention is used as a raw material for producing the foamed laminated sheet (unfoamed raw fabric).

3. Foamed laminated sheet and method for producing laminated sheet The foamed laminated sheet and laminated sheet of the present invention are produced , for example, by the following production method, but are not limited thereto. In the following description of the production method, the contents already described in the section of “1. Foamed laminated sheet” regarding the foamed laminated sheet, the method of forming each layer constituting the laminated sheet, the method of forming the air holes, etc. Omit.

  First, a foaming agent-containing resin layer is formed on a substrate by melt molding (first step). When the non-foamed resin layer A and / or the non-foamed resin layer B is provided, the non-foamed resin layer A and / or the non-foamed resin layer is used together with the foaming agent-containing resin layer using a multi-manifold type T die. It is desirable to coextrude B.

  What is necessary is just to set suitably according to the kind etc. of the resin component to be used about the cylinder temperature and die temperature at the time of extruding and forming a foaming agent containing resin layer with a T-die extruder, but generally it is about 100-140 degreeC.

  In the first step, the foaming agent-containing resin layer is directly extruded onto the base material by melt molding, and the base material and the foaming agent-containing resin layer (non-foaming resin layer A as required) are utilized by utilizing the adhesiveness by heat melting. And / or non-foamed resin layer B) may be adhered, and a foaming agent-containing resin layer (non-foamed resin layer A and / or non-foamed resin layer B as required) is prepared in advance and heated. The substrate may be thermocompression bonded.

  Next, a pattern protective layer is formed on the foaming agent-containing resin layer (or non-foamed resin layer A) as necessary, and then a surface protective layer is formed (second step). When the surface protective layer is a cured resin layer, a crosslinking treatment is performed to cure the curable resin. Moreover, also when a surface protective layer is a crosslinkable thermoplastic resin layer, such as polyethylene and an ethylene-type copolymer, you may perform a crosslinking process to the said thermoplastic resin layer as needed.

  Thus, a laminated sheet (ventilation hole not formed) in which the foaming agent-containing resin layer and the surface protective layer are sequentially laminated on the substrate is prepared.

  After the formation of the surface protective layer, the foaming agent-containing resin layer is converted into a foamed resin layer by foaming the foaming agent-containing resin layer (third step). The conditions for foaming the foaming agent-containing resin layer are appropriately set according to the type of foaming agent, and examples include a method of heat treatment at a heating temperature of about 210 to 240 ° C. and a heating time of about 20 to 80 seconds.

  After the first step or the second step, in order to adjust the melt tension of the foaming agent-containing resin layer and easily obtain a desired foaming ratio, a crosslinking treatment is performed on the foaming agent-containing resin layer as necessary. It can be performed. As described above, when the surface protective layer is also subjected to a crosslinking treatment, the foaming agent-containing resin layer and the surface protective layer may be crosslinked simultaneously after the second step.

  In the production of the foamed laminated sheet of the present invention, the perforating step for forming the air holes is performed after the second step or after the third step. That is, after the second step, after performing the drilling step of forming at least air holes penetrating the surface protective layer and the foaming agent-containing resin layer to obtain the laminated sheet of the present invention, the third step is performed. May be. Further, after the third step, a drilling step of forming a vent hole penetrating at least the surface protective layer and the foamed resin layer may be performed. Thus, the foamed laminated sheet and laminated sheet of the present invention are produced.

  Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the examples.

Example 1
Using a three-type three-layer T-die extruder, the film is extruded onto a fibrous sheet so that the thickness is 8 μm / 60 μm / 8 μm in the order of non-foamed resin layer A / foaming agent-containing resin layer / non-foamed resin layer B. did. Thereby, the laminated body which consists of non-foaming resin layer A / foaming agent containing resin layer / non-foaming resin layer B / fibrous sheet was obtained. As the fibrous sheet, wallpaper paper “WK-665, manufactured by Kojin” was used.

  Extrusion conditions were such that the cylinder temperature containing the resin for forming the non-foamed resin layer A was 130 ° C., the cylinder temperature containing the resin composition for forming the foaming agent-containing resin layer was 120 ° C., and non-foamed The temperature of the cylinder containing the resin for forming the resin layer B was 120 ° C. The die temperature was 120 ° C. for all.

Each layer was formed using the following components.
The non-foamed resin layer A was formed by EMAA (“Nucleel N1560”, manufactured by Mitsui DuPont Polychemical).

  The foaming agent-containing resin layer is composed of 100 parts by weight of EMAA (“Nucrel N1110H”, manufactured by Mitsui DuPont Polychemical), 30 parts by weight of calcium carbonate (“Whiteon H”, manufactured by Shiroishi Kogyo), and a colorant (“Tai Pure R350”, It was formed by 20 parts by weight of DuPont), 5 parts by weight of a foaming agent (“Vinole AC # 3”, manufactured by Eiwa Kasei Kogyo), and 5 parts by weight of a foaming aid (“ADHS”, manufactured by Otsuka Chemical).

  The non-foamed resin layer B was formed by EVA (“Ultrasen 750”, manufactured by Tosoh Corporation).

  Next, after the non-foamed resin layer A was subjected to corona discharge treatment, a textile pattern was printed using a water-based ink (“Hydric”, manufactured by Dainichi Seika Kogyo Co., Ltd.) as a pattern print by a gravure printing machine to form a pattern pattern layer.

  Thereafter, using an extruder, a thermoplastic resin layer (surface protective layer) was extruded and formed on the surface of the pattern layer so as to have a thickness of 10 μm, and was laminated on the pattern layer. The extrusion conditions were 300 ° C. for both the cylinder and the die. As a raw material for the surface protective layer, low density polyethylene (LDPE) ("Novatech LC600A", manufactured by Nippon Polyethylene) (MFR = 7) was used. Thereafter, the surface of the thermoplastic resin layer (surface protective layer) was irradiated with an electron beam under the conditions of an acceleration voltage of 195 kV and an irradiation dose of 50 kGy.

Next, the obtained laminated sheet is heated in an oven (220 ° C., 35 seconds) to foam the foaming agent-containing resin layer so that the total thickness of the laminated sheet becomes 580 μm, and then embossing with a texture is performed. This was done to obtain a foamed laminated sheet (no hole formed state). Using a CO ₂ laser, the foamed laminated sheet (holes not formed) was perforated in a lattice shape with a pore diameter of 250 μm and a pitch of 2 mm, and vent holes (through holes) were formed in the foamed laminated sheet. The opening area of the obtained foamed laminated sheet was 1.23 mm ² / cm ² .

Example 2
A foamed laminated sheet was produced in the same manner as in Example 1 except that through holes were formed by perforating in a lattice pattern at a hole diameter of 50 μm and a pitch of 2 mm. The opening area of the obtained foamed laminated sheet was 0.05 mm ² / cm ² .

Example 3
A foamed laminated sheet was produced in the same manner as in Example 1 except that through holes were formed by perforating in a lattice shape at a hole diameter of 200 μm and a pitch of 5 mm. The opening area of the obtained foamed laminated sheet was 0.12 mm ² / cm ² .

Example 4
Under the same conditions as in Example 1, a laminate comprising a thermoplastic resin layer / pattern pattern layer / non-foamed resin layer A / foaming agent-containing resin layer / non-foamed resin layer B / fibrous sheet was obtained. Next, an ionizing radiation curable resin composition was applied on the thermoplastic resin layer of the laminate by a gravure direct coater method at a coating amount of 2.0 g / m ² . The ionizing radiation curable resin composition used consisted of 100 parts by mass of urethane acrylate, 10 parts by mass of silica, and 5 parts by mass of methyl butyl ketone. Then, the cured resin layer was formed on the thermoplastic resin layer by irradiating the layer of the ionizing radiation curable resin composition with an electron beam under conditions of an acceleration voltage of 200 kV and an irradiation dose of 50 kGy.

Next, the obtained laminated sheet was foamed, embossed, and perforated under the same conditions as in Example 1 to produce a foamed laminated sheet having vent holes (through holes). The opening area of the obtained foamed laminated sheet was 1.23 mm ² / cm ² .

Example 5
Under the same conditions as in Example 1, a laminate comprising a pattern layer / non-foamed resin layer A / foaming agent-containing resin layer / non-foamed resin layer B / fibrous sheet was obtained. Next, this laminate was subjected to application of an ionizing radiation curable resin composition and electron beam irradiation under the same conditions as in Example 4 to form a cured resin layer on the pattern layer.

Next, the obtained laminated sheet was foamed, embossed, and perforated under the same conditions as in Example 1 to produce a foamed laminated sheet having vent holes (through holes). The opening area of the obtained foamed laminated sheet was 1.23 mm ² / cm ² .

Comparative Example 1
The emulsion resin composition was coated on a fibrous sheet, and a foaming agent-containing resin layer having a thickness of 100 μm was laminated. As the fibrous sheet, wallpaper paper “WK-665, manufactured by Kojin” was used. Moreover, as an emulsion resin composition, ethylene-vinyl acetate resin 55 mass parts, aluminum hydroxide 100 mass parts, titanium oxide 3 mass parts, a dispersing agent "poise", Kao make 1 mass part, foaming agent ("AZ- B 95 ", manufactured by Otsuka Chemical Co., Ltd.) 10 parts by mass, a foaming agent (" F-85 ", Matsumoto Yushi Seiyaku Co., Ltd.) 0.5 parts by mass, and water 110 parts by mass were used.

  Next, the foaming agent-containing resin layer was subjected to corona discharge treatment, and then a textile pattern was printed as a pattern print using a water-based ink (“Hydric”, manufactured by Dainichi Seika Kogyo Co., Ltd.) by a gravure printing machine to form a pattern pattern layer.

Thereafter, under the same conditions as in Example 1, formation of a surface protective layer surface, heat foaming, embossing treatment, and perforation were performed to produce a foamed laminated sheet having vent holes (through holes). The opening area of the obtained foamed laminated sheet was 1.23 mm ² / cm ² .

Comparative Example 2
Apply vinyl chloride paste sol 250g / m2 by a comma coat method to 65g / m2 wallpaper backing paper [Kojin Co., Ltd .: WK-665 (trade name)], and dry it at 150 ° C for 1 minute. A sol layer was formed. The vinyl chloride paste sol includes 100 parts by weight of vinyl chloride resin, 110 parts by weight of calcium carbonate, 4.5 parts by weight of a foaming agent (azodicarbonamide), 50 parts by weight of a plasticizer (diisononyl phthalate), and a stabilizer (epoxidation). 2 parts by weight of soybean oil, 5 parts by weight of stabilizer (“FL-47” manufactured by ADEKA), 23 parts by weight of liquid toner (manufactured by Nihongo Bix) “DE-24”, diluent (Shell Japan “Shellsol S”) The amount was 20 parts by weight.

  Next, the foaming agent-containing resin layer was subjected to corona discharge treatment, and then a textile pattern was printed as a pattern print using a water-based ink (“Hydric”, manufactured by Dainichi Seika Kogyo Co., Ltd.) by a gravure printing machine to form a pattern pattern layer.

Thereafter, under the same conditions as in Example 1, formation of a surface protective layer surface, heat foaming, embossing treatment, and perforation were performed to produce a foamed laminated sheet having vent holes (through holes). The opening area of the obtained foamed laminated sheet was 1.23 mm ² / cm ² .

Test Example 1 (Evaluation of moisture permeability, stain resistance, and phase peelability)
About each foaming lamination sheet of Example 1-5 and Comparative Example 1-2, moisture permeability, stain resistance, and phase peeling property were evaluated in accordance with the following method.

Evaluation of moisture permeability The water vapor permeability of each foamed laminated sheet was measured according to the method defined in JIS Z 0208. The measurement of moisture permeability was performed under the conditions of 40 ° C. and relative humidity 90%.

Further, regarding the moisture permeability of each foamed laminated sheet, the case where the water vapor transmission rate was 200 g / m ² · 24 hr or more was judged as ◯, and the case where the water vapor transmission rate was less than 200 g / m ² · 24 hr was judged as x.

Evaluation of stain resistance Each foamed laminated sheet (length 30 cm, width 20 cm) was left for 24 hours in a state where 50 mL of coffee was spilled, then the coffee was wiped off, each foamed laminated sheet was washed with water, and then visually The degree of contamination of each foamed laminated sheet was confirmed, and the stain resistance was evaluated according to the following criteria.
<Criteria for contamination resistance>
○: No residual coffee is observed in the vent holes of the foamed laminated sheet.
Δ: Residual coffee was slightly observed in the vent portion of the foamed laminated sheet, but there is no practical problem.
X: Residual coffee was remarkably observed in the vent holes of the foamed laminated sheet.

Evaluation of phase peelability After applying glue to the back of each foamed laminated sheet (the surface of the fibrous sheet) at 130 g / m ² and bringing the glued surfaces into close contact with each other, they are stored in a polyethylene bag and left for 24 hours. did. Thereafter, the glued surfaces that were brought into close contact with each other were peeled off to evaluate the appearance.

  The evaluation results of moisture permeability and contamination resistance are shown in Table 1. As is clear from Table 1, in the foamed laminated sheet of Comparative Example 1-2 in which the foamed resin layer was formed by a technique other than melt molding, contaminants remained in the vent portion, and the stain resistance was impaired. On the other hand, in the foamed laminated sheet of Example 1-5 in which the foamed resin layer was formed by melt molding, no contaminants remained in the vent portion, and excellent stain resistance was provided. In particular, the foamed laminated sheets having the thermoplastic resin layers of Examples 1 to 4 are remarkably superior in stain resistance, applied with black magic that is more easily recognized than coffee, and rubbed for 24 hours. However, the ink was removed by wiping with ethanol, and contamination was hardly observed. In addition, all of the foamed laminated sheets of Example 1-5 also had good moisture permeability.

Regarding the phase peelability, in the foamed laminated sheet of Comparative Example 1, the glued surfaces were difficult to peel apart, and part of the glued surface after peeling was peeled off, but in the foamed laminated sheet of Example 1-5 The gluing surfaces were easily peeled off, and the gluing surfaces after peeling were kept in a clean state in which the construction glue was uniformly applied.

Claims (8)

  A foamed resin layer formed by melt molding and a surface protective layer are sequentially laminated on a base material, and has at least a vent hole penetrating the surface protective layer and the foamed resin layer. A foamed laminated sheet.   The foaming laminated sheet of Claim 1 whose average hole diameter of the said ventilation hole in the surface of the said surface protective layer is 50-300 micrometers.   The foam laminate sheet according to claim 1 or 2, wherein the surface protective layer contains a thermoplastic resin. The foamed laminated sheet according to any one of claims 1 to 3, wherein the foamed resin layer is crosslinked.   The foaming laminated sheet in any one of Claims 1-3 which has a non-foaming resin layer between the said base material and the said foaming resin layer, and / or between the said foaming resin layer and the said surface protective layer.   On the base material, a foaming agent-containing resin layer formed by melt molding and a surface protective layer are sequentially laminated, and at least have a vent hole penetrating the surface protective layer and the foaming agent-containing resin layer. A laminated sheet characterized by that. A method for producing a foamed laminated sheet having air holes,
A first step of forming a foaming agent-containing resin layer on the substrate by melt molding;
A second step of forming a surface protective layer on the foaming agent-containing resin layer, and a third step of foaming the foaming agent-containing resin layer to form a foamed resin layer,
And after the said 2nd process or the 3rd process, the manufacturing method of the foaming laminated sheet characterized by including the drilling process which forms the vent hole which penetrates at least the said surface protective layer and the said foamed resin layer. The manufacturing method of the foaming lamination sheet of Claim 7 which performs a crosslinking process with respect to a foaming agent containing resin layer after the said 1st process or a 2nd process.