JP6221304B2 - FOAM SHEET, FOAM LAMINATED SHEET AND METHOD FOR PRODUCING THEM - Google Patents

Description

  The present invention relates to a foam sheet, a foam laminate sheet, and a method for producing them.

  Conventionally, in order to increase the foaming volume of the entire foamed wallpaper, it is known to make the foamed layer of the foamed wallpaper highly foamed. In this case, it is required to reduce the content of the inorganic additive that hinders foaming.

  However, if the content of the inorganic additive contained in the foam layer is reduced, the concealability required for wallpaper may be insufficient.

  As one method for improving the above problem, it is known to separately provide a layer containing a shielding material (hereinafter also referred to as a shielding layer) on the foam layer. According to this method, the concealability can be ensured by the concealment layer.

  However, when a large amount of pigment is used to ensure concealment, (1) eyeslip is generated in the die slip during extrusion film formation, (2) holes are formed in the formed concealment layer, (3) When an electron beam is applied to a foaming agent-containing resin layer for forming a foamed layer to give a resin crosslinking effect, there is a problem that sufficient crosslinking cannot be obtained due to the shielding effect of the pigment. . Therefore, there is room for further improvement.

Japanese Unexamined Patent Publication No. 2000-071365

  The present invention provides a foamed laminated sheet having excellent concealability without using a large amount of an inorganic additive while ensuring the foaming volume of the whole foamed laminated sheet, and a foamed sheet useful for producing the foamed laminated sheet The purpose is to provide.

  The present invention has found that the object can be achieved by a foamed sheet having two different foamed layers and a foamed laminated sheet obtained by laminating a base material or the like on the foamed sheet, and has completed the present invention.

That is, the present invention relates to the following foamed sheet and foamed laminated sheet.
1. a foam sheet having at least a first foam layer and a second foam layer,
(1) In the first foam layer, the number of foam cells having a major axis of 100 μm or more is 50% or more of the total number of foam cells constituting the first foam layer,
(2) In the second foam layer, the number of foam cells having a major axis of less than 100 μm is 50% or more of the total number of foam cells constituting the second foam layer,
(3) The first foam layer is obtained by foaming a foaming agent-containing resin layer,
The blowing agent remelted and kneaded containing resin layer and the second foamed layer state, and are the total light transmittance of the resin composition was molded to 150μm thick sheet is 70% or more,
(4) The thickness of the first foam layer is 300 to 700 μm.
A foamed sheet characterized by the above.
2. A foam laminate sheet in which a first foam layer and a second foam layer are laminated in order on a substrate,
(1) In the first foam layer, the number of foam cells having a major axis of 100 μm or more is 50% or more of the total number of foam cells constituting the first foam layer,
(2) In the second foam layer, the number of foam cells having a major axis of less than 100 μm is 50% or more of the total number of foam cells constituting the second foam layer,
(3) The first foam layer is obtained by foaming a foaming agent-containing resin layer,
The blowing agent remelted and kneaded containing resin layer and the second foamed layer state, and are the total light transmittance of the resin composition was molded to 150μm thick sheet is 70% or more,
(4) The thickness of the first foam layer is 300 to 700 μm.
A foamed laminated sheet characterized by that.
3. The foamed laminated sheet according to Item 2, wherein the first foamed layer is obtained by foaming a foaming agent-containing resin layer that is resin-crosslinked by electron beam irradiation.
4. The foamed laminated sheet according to Item 2 or 3, wherein the second foamed layer is resin-crosslinked by electron beam irradiation.

≪Foam sheet≫
The foam sheet of the present invention is a foam sheet having at least a first foam layer and a second foam layer,
(1) In the first foam layer, the number of foam cells having a major axis of 100 μm or more is 50% or more of the total number of foam cells constituting the first foam layer,
(2) In the second foam layer, the number of foam cells having a major axis of less than 100 μm is 50% or more of the total number of foam cells constituting the second foam layer.
It is characterized by
Since the foam sheet of the present invention having the above characteristics has the above two different specific foam layers, it has excellent concealability without using a large amount of an inorganic additive while ensuring the foam volume of the entire foam laminate sheet. This is useful for the production of foamed laminated sheets.

  The layer structure of the foam sheet of the present invention is not particularly limited as long as it has a first foam layer and a second foam layer. For example, (i) a layer structure composed of a first foam layer and a second foam layer, (ii) a non-foam resin layer B, a first foam layer, a non-foam resin layer A and a second foam layer in that order. The layer structure which has is mentioned. Hereinafter, each layer will be described by taking the layer configuration (ii) as an example.

First foam layer The foam sheet of the present invention has a first foam layer.

  In the first foam layer, the number of foam cells having a major axis of 100 μm or more is 50% or more of the total number of foam cells constituting the first foam layer. That is, the first foam layer showing the closed cell structure has a large number of foam cells (bubbles), and the foam cell of half or more of the total number of the foam cells has a major axis of 100 μm or more. Therefore, the foam volume of the foam sheet (and the foam laminate sheet) can be secured.

  The major axis of the foamed cell means the length of a line connecting two farthest points in each foamed cell visible from the microscope. The major axis can be measured using a microscope (for example, an optical microscope). In the present invention, the major axis of the foamed cell is measured by a digital microscope VHX-100 (observation magnification 100 times) manufactured by Keyence Corporation.

In the present invention, the ratio of the number of foam cells having a major axis of 100 μm or more to the total number of foam cells in the first foam layer is represented by the following procedures (1) to (3):
(1) A foam sheet having a length of 5 mm (note that the length refers to the length in the horizontal direction of the foam sheet, and the thickness (thickness) of the foam sheet refers to the length in the vertical direction), Prepare a foam sheet that can observe the cross section of the first foam layer,
(2) The thickness of the first foam layer is vertical, and the first foam layer cross-sectional area with the length (1 mm) is observed with a microscope,
(3) (a) the total number of foam cells included in the first foam layer cross-sectional area, (b) the major diameter of each foam cell, and (c) the number of foam cells whose major diameter is 100 μm or more.
It is gained by.

  The resin component contained in the first foamed layer is at least one of 1) polyethylene and 2) an ethylene copolymer having monomers other than ethylene and ethylene (hereinafter abbreviated as “ethylene copolymer”). Species are preferred.

  As the polyethylene, low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), and the like can be widely used. Among these, low-density polyethylene is preferable.

  Ethylene copolymers are suitable for extrusion film formation in terms of melting point and MFR. Examples of the ethylene copolymer include an ethylene-vinyl acetate copolymer (EVA), an ethylene-acrylic acid copolymer (EAA), an ethylene-methacrylic acid copolymer (EMAA), and an ethylene-methyl methacrylate copolymer ( EMMA), ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-α olefin copolymer, and the like.

  In the first foam layer, the ethylene resin and another resin may be used in combination as a resin component. When used in combination, the content of the ethylene-based resin is preferably 70% by mass or more, and more preferably 80% by mass or more.

  In addition, the content of monomers other than ethylene in the ethylene copolymer can further enhance the extrusion film forming property by adopting an appropriate copolymerization ratio depending on the components to be copolymerized. Specifically, in the case of an ethylene-vinyl acetate copolymer, the copolymerization ratio (VA amount) of vinyl acetate is preferably 5 to 40% by mass, and more preferably 10 to 30% by mass. In the case of an ethylene-acrylic acid copolymer, the copolymerization ratio (AA amount) of acrylic acid is preferably 2 to 15% by mass, and more preferably 5 to 11% by mass. In the case of an ethylene-methacrylic acid copolymer, the copolymerization ratio (MAA amount) of methacrylic acid is preferably 2 to 15% by mass, and more preferably 5 to 11% by mass. Moreover, in the case of an ethylene-alpha olefin copolymer, 0.5-50 mass% is preferable as a copolymerization ratio of alpha olefin.

  The melt flow rate of the resin component contained in the first foam layer (melt flow rate (MFR) measured under the conditions of 190 ° C. and load of 21.18 N described in JIS K 6922) is the molding method of the foam-containing resin layer described later. What is necessary is just to set suitably according to. For example, when the foaming agent-containing resin layer is formed by extrusion molding, the MFR is preferably 10 to 35 g / 10 min. When a foaming agent-containing resin layer containing a resin component having an MFR within the above range is formed by extrusion film formation, the temperature rise is small and film formation can be performed in a non-foamed state. Therefore, when the pattern layer is formed later, the printing process can be performed on a smooth surface, and there are few pattern omissions. If the MFR is too large, the resin is too soft and the resulting foamed resin layer may have insufficient scratch resistance. On the other hand, when the foaming agent-containing resin layer is formed by calendar molding, the MFR is preferably 0.5 to 20 g / 10 min.

  The first foam layer is obtained by foaming the foaming agent-containing resin layer. That is, the foamed sheet can be obtained by foaming at least the foaming agent-containing resin layer and the foaming agent-containing resin layer of the raw sheet for foaming sheet having the second foaming layer described later. The relationship between the foam sheet and the foam sheet raw material is the relationship between the finished product and the intermediate, and the foamed resin layer formed by foaming the foam sheet original fabric having the foaming agent-containing resin layer is foamed. It is a sheet. Similarly, the foamed laminated sheet described later foams the foaming agent-containing resin layer of the raw material for the foamed laminated sheet having at least a foaming agent-containing resin layer and a second foamed layer on the base material, The foamed laminated sheet and the foamed laminated sheet original are in a relationship between the finished product and the intermediate.

  As the resin composition for forming the foaming agent-containing resin layer (first foaming layer-forming resin composition), for example, a resin composition containing the above resin component, foaming agent, foaming aid, crosslinking aid, etc. is suitable. Can be used for In addition, inorganic fillers, stabilizers, lubricants, and the like can be used as additives to the extent that the effects of the present invention are not impaired.

  Examples of the thermally decomposable foaming agent include azo series such as azodicarbonamide (ADCA) and azobisformamide; hydrazide series such as oxybenzenesulfonyl hydrazide (OBSH) and paratoluenesulfonyl hydrazide. The content of the pyrolytic 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 4 times or more, preferably about 5 to 10 times, and the pyrolytic foaming agent is preferably about 1 to 20 parts by mass with respect to 100 parts by mass of the resin component.

  As the microcapsule type foaming agent, for example, a known or commercially available one can be used. For example, a microscopic material in which a volatile liquid expansion agent such as propane, butane, isobutane, pentane, hexane or the like is encapsulated in a thermoplastic polymer shell such as vinylidene chloride-acrylonitrile-divinylbenzene copolymer or methacrylate-acrylonitrile-divinylbenzene copolymer. A capsule etc. are mentioned. The average particle size of the microcapsule type foaming agent is preferably about 10 to 40 μm. From the viewpoint of the expansion ratio, it is 2 times or more, preferably about 3 to 6 times, and the microcapsule type foaming agent is preferably about 1 to 10 parts by mass with respect to 100 parts by mass of the resin component.

The foaming aid is preferably a metal oxide and / or a fatty acid metal salt. For example, zinc stearate, calcium stearate, magnesium stearate, zinc octylate, calcium octylate, magnesium octylate, zinc laurate, calcium laurate, laurin Magnesium acid, zinc oxide, magnesium oxide and the like can be used. About 0.3-10 mass parts is preferable with respect to 100 mass parts of resin components, and, as for content of these foaming adjuvants, about 1-5 mass parts is more preferable.

  When these foaming aids, EMAA-like copolymers having a carboxyl group in the molecule and ADCA foaming agent are used in combination, in the foaming step, the carboxyl group portion of the copolymer and the foaming aid are used. There is a problem that the effect of the original foaming aid is impaired by the reaction of the agent. Therefore, when used in combination with a copolymer having a carboxyl group in the molecule, such as EMAA, and an ADCA foaming agent, as explained in Japanese Laid-Open Publication No. 2009-197219, as a foaming aid It is preferable to use a carboxylic acid hydrazide compound. At this time, the carboxylic acid hydrazide compound is preferably used in an amount of about 0.2 to 1 part by mass with respect to 1 part by mass of the ADCA foaming agent.

Examples of the inorganic filler include calcium carbonate, aluminum hydroxide, magnesium hydroxide, antimony trioxide, zinc borate, molybdenum compound, and talc. By including an inorganic filler, an effect of suppressing see-through, an effect of improving surface characteristics, and the like are obtained. About 0-20 mass parts is preferable with respect to 100 mass parts of resin components, and, as for content of an inorganic filler, about 1-10 mass parts is more preferable.

  In the present invention, the foaming agent-containing resin layer may be resin-crosslinked by electron beam irradiation. What is necessary is just to implement according to the method described in the postscript manufacturing method as a method of irradiating an electron beam to a foaming agent containing resin layer, and the method of making it foam. The thickness of the foaming agent-containing resin layer is preferably about 40 to 100 μm, and the thickness of the first foamed layer after foaming is preferably about 300 to 700 μm.

Non-foamed resin layers A and B
The foamed sheet of the present invention may have a non-foamed resin layer on one side or both sides of the first foamed layer.

  For example, the back surface of the first foam layer (the surface on which the base material is laminated) may have a non-foamed resin layer B (adhesive resin layer) for the purpose of improving the adhesive strength with the base material.

  The resin component of the adhesive resin layer is not particularly limited, but an ethylene-vinyl acetate copolymer (EVA) is preferable. As the EVA, a known or commercially available EVA can be used. In particular, the vinyl acetate component (VA component) is preferably 10 to 46% by mass, more preferably 15 to 41% by mass.

  The thickness of the adhesive resin layer is not limited, but is preferably about 5 to 50 μm.

  A non-foamed resin layer A may be provided on the upper surface of the first foam layer for the purpose of improving the scratch resistance of the first foam layer.

  Examples of the resin component of the non-foamed resin layer A include polyolefin resins, methacrylic resins, thermoplastic polyester resins, polyvinyl alcohol resins, and fluorine resins. Of these, polyolefin resins are preferred.

  Examples of the polyolefin resin include polyethylene, polypropylene, polybutene, polybutadiene, polyisoprene, and the like, a copolymer of ethylene and an α-olefin having 4 or more carbon atoms (linear low density polyethylene), ethylene-acrylic acid copolymer, and the like. Polymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene- (meth) acrylic acid copolymer such as ethylene-methacrylic acid copolymer (EMAA), ethylene-vinyl acetate copolymer Examples thereof include at least one of a polymer (EVA), a saponified ethylene-vinyl acetate copolymer, and an ionomer. Note that “(meth) acryl” means acryl or methacryl, and the same applies to other similar portions.

  The thickness of the non-foamed resin layer A is not limited, but is preferably about 5 to 50 μm.

Second foam layer The foam sheet of the present invention has a second foam layer.

  In the second foam layer, the number of foam cells having a major axis of less than 100 μm is 50% or more of the total number of foam cells constituting the first foam layer. That is, the first foam layer showing the closed cell structure has a large number of foam cells (bubbles), and the foam cell of half or more of the total number of the foam cells has a major axis of less than 100 μm. More than half of the fine foam cells impart concealability to the foam sheet.

  In the present invention, the method for calculating the ratio of the number of foam cells whose major axis is less than 100 μm with respect to the total number of foam cells in the second foam layer is that the major axis with respect to the total number of foam cells in the first foam layer is 100 μm or more. This is the same as the method for calculating the ratio of the number of foam cells.

  The explanation of the resin component contained in the second foam layer is the same as the explanation of the resin component contained in the first foam layer. For example, as the resin component contained in the second foam layer, the same resin component as the resin component contained in the first foam layer can be used.

  The second foam layer is obtained by adding a supercritical fluid to the second foam layer-forming resin composition and then subjecting the foam composition to foam extrusion.

  As the second foam layer forming resin composition, for example, a resin composition containing the above resin component, inorganic filler, crosslinking aid and the like can be suitably used. In addition, stabilizers, lubricants and the like can be used as additives.

  The inorganic filler can be used as a so-called foam nucleating agent that gives the effect of forming finer foam cells. Examples of the inorganic filler include calcium carbonate, aluminum hydroxide, magnesium hydroxide, antimony trioxide, zinc borate, molybdenum compound, and talc. The content of the inorganic filler is preferably about 0 to 10 parts by mass and more preferably about 0.3 to 5 parts by mass with respect to 100 parts by mass of the resin component.

  In the present invention, the second foamed layer may be resin-crosslinked by electron beam irradiation. When the second foamed layer is resin-crosslinked by electron beam irradiation, heat resistance and strength are improved. Therefore, when giving the embossing pattern by the embossing mentioned later, it is excellent in the said embossing moldability. The method of irradiating the second foamed layer with the electron beam may be carried out according to the method described in the production method described later. The thickness of the second foam layer is preferably about 100 to 500 μm.

  The resin composition obtained by remelting and kneading the foaming agent-containing resin layer and the second foamed layer in which the first foamed layer is in an unfoamed state preferably has a total light transmittance of 70% or more. . In this case, when the material is remelted and returned to the first and / or second foamed layer forming resin composition which is a raw material, the raw material is less colored. In addition, remelting is easy to perform when the formation method of the said foaming agent containing resin layer is extrusion molding or calendar molding.

  In order to make the total light transmittance of the resin composition obtained by remelting and kneading 70% or more, it can be adjusted by, for example, coloring components, concealing components, transparent resin content, etc. .

  The total light transmittance in the present invention is based on JIS K7361, and specifically, measured using a DIRECT READING HAZE METER manufactured by Toyo Seiki Seisakusho Co., Ltd.

≪Foamed laminated sheet≫
The foam laminate sheet of the present invention is a foam laminate sheet in which a first foam layer and a second foam layer are sequentially laminated on a substrate,
(1) In the first foam layer, the number of foam cells having a major axis of 100 μm or more is 50% or more of the total number of foam cells constituting the first foam layer,
(2) In the second foam layer, the number of foam cells having a major axis of less than 100 μm is 50% or more of the total number of foam cells constituting the second foam layer.
It is characterized by that.

  The foamed laminated sheet of the present invention having the above characteristics has the above-mentioned two specific foamed layers, so that the foaming volume of the whole foamed laminated sheet is ensured and concealment is achieved without using a large amount of inorganic additives. Excellent.

The layer configuration of the foamed laminated sheet of the present invention is not particularly limited as long as the first foamed layer and the second foamed layer are sequentially laminated on the base material. For example, (i) a layer configuration having a first foamed layer and a second foamed layer in that order on the substrate, (ii) a non-foamed resin layer B, a first foamed layer, a non-foamed on the substrate A layer structure having a resin layer A and a second foam layer in that order; (iii) a non-foam resin layer B, a first foam layer, a non-foam resin layer A, a second foam layer, and a pattern on the substrate; Examples include a layer configuration having a layer and a protective layer in that order. The description of the first foam layer, the second foam layer, the non-foamed resin layer A, and the non-foamed resin layer B is the same as the description of each layer in the above-described foamed sheet.
In the foamed laminated sheet of the present invention, the second foamed layer is a so-called “front surface” (surface visually recognized after construction). Therefore, in this specification, the direction in which the second foamed layer is present with respect to the substrate is referred to as “front” or “upper”, and the opposite side is referred to as “back” or “lower”.

Not limited as the substrate base material, a known fibrous substrate (backing sheet), etc. can be used.

  Specifically, wallpaper general paper (pulp-based sheet sized with a known sizing agent); flame-retardant paper (pulp-based sheet 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 (paper made by mixing pulp and synthetic fiber). In addition, what corresponds to a nonwoven fabric on classification is included in these fibrous base materials.

Patterned Pattern Layer The foamed laminated sheet of the present invention may have a patterned pattern layer. The pattern pattern layer can be formed on the second foam layer, for example.

  The pattern layer imparts design properties to the foamed laminated 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 selected according to the kind of foam 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, and a solvent can be used. These inks may be known or commercially available.

  As the colorant, inorganic pigments, organic pigments, and the like can be used as appropriate. 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), cadmium red. , Ultramarine, bitumen, cobalt blue, chromium oxide, cobalt green, aluminum powder, bronze powder, titanium mica, zinc sulfide and the like. 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).

  The binder resin is, for example, an acrylic resin, a styrene resin, a polyester resin, a urethane resin, a chlorinated polyolefin resin, a vinyl chloride-vinyl acetate copolymer resin, a polyvinyl butyral resin, an alkyd resin, or a petroleum resin. Examples include resins, ketone resins, epoxy resins, melamine resins, fluorine resins, silicone resins, fiber derivatives, rubber resins, and the like.

  Examples of the solvent (or dispersion medium) include petroleum organic solvents such as hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane, and methylcyclohexane; ethyl acetate, butyl acetate, acetic acid-2-methoxyethyl, acetic acid-2 -Ester-based organic solvents such as ethoxyethyl; alcohol-based organic solvents such as methyl alcohol, ethyl alcohol, normal propyl alcohol, isopropyl alcohol, isobutyl alcohol, ethylene glycol, propylene glycol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone Organic solvents such as diethyl ether, dioxane, and tetrahydrofuran; dichloromethane, carbon tetrachloride, trichloroethylene, tetrachloroethylene, etc. Containing organic solvent; and water. These solvents (or dispersion media) can be used alone or in the form of a mixture.

  The thickness of the design pattern layer is different from the type of design pattern, but is generally preferably about 0.1 to 10 μm.

Protective layer The foamed laminated sheet of the present invention may have a protective layer. The protective layer can be formed on the surface of the second foam layer or the pattern layer, for example. A protective layer is a layer formed in order to adjust the glossiness of the surface of a foaming laminated sheet or a foaming laminated sheet raw material, or to give intensity | strength and stain resistance to a surface. Further, when the pattern layer is provided on the foam laminate sheet or the foam laminate sheet original, the protective layer is a layer formed on the pattern layer as necessary to protect the pattern layer. .

  What is necessary is just to select suitably from well-known resin components, such as a thermoplastic resin and a curable resin, as a resin component used for formation of a protective layer.

  Examples of the thermoplastic resin used for forming the protective layer include polyolefin resins, acrylic resins, polyvinyl alcohol resins, and fluorine resins. Among these thermoplastic resins, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer are preferable. Ethylene (meth) acrylic acid copolymer resin such as ethylene-vinyl acetate copolymer (EVA); Saponified ethylene-vinyl acetate copolymer resin; Ionomer; Ethylene copolymer such as ethylene-olefin copolymer A polyolefin resin such as polyethylene or polypropylene; These thermoplastic resins may be used alone or in combination of two or more. Further, when a crosslinkable thermoplastic resin such as an ethylene copolymer is used for forming the protective layer, the thermoplastic resin may be subjected to a crosslinking treatment as necessary.

  Further, the curable resin used for forming the protective layer is not particularly limited, and for example, a room temperature curable resin, a heat curable resin, an ionizing radiation curable resin, a one-component reaction curable resin, and a two-component reaction curable resin. Any of a curable resin, an ionizing radiation curable resin and the like may be used, but a one-component reaction curable resin is preferable. Among these curable resins, acrylic resins, urethane resins, and the like are preferable, and one-component reaction curable acrylic resins are more preferable. These curable resins may be used alone or in combination of two or more. Moreover, when using curable resin for formation of a protective layer, in order to advance hardening reaction, you may use a crosslinking agent, a polymerization initiator, a polymerization accelerator, etc. as needed.

  Further, the protective layer may be a single layer, or two or more layers that are the same or different may be laminated. For example, it may have a two-layer structure in which a layer formed of a curable resin is formed on the outermost surface and a layer formed of a thermoplastic resin is laminated on the lower layer.

  Although the thickness of a protective layer is not specifically limited, For example, 1-20 micrometers is preferable and 1-15 micrometers is more preferable.

  The protective layer may be formed by a method corresponding to the type of resin component used. For example, in the case of forming a protective layer using a thermoplastic resin, the protective layer may be formed by pasting a thermoplastic resin film prepared in advance to the surface of the pattern layer. The protective layer may be formed by extruding a thermoplastic resin on the surface of the layer to form a film.

  In the case of forming a protective layer using a curable resin, for example, a resin composition containing various additives as required in the curable resin can be used as a gravure coat, a bar coat, a roll coat, a reverse roll. After coating the second foamed layer or pattern layer by a method such as coating or comma coating, the resin composition is dried and cured by heating or the like, if necessary.

  In addition, before forming the protective layer, a surface treatment such as corona treatment or plasma treatment, or a primer layer may be provided on the surface of the second foam layer or the pattern layer in consideration of adhesiveness.

  As the resin contained in the primer layer, for example, acrylic resin, vinyl chloride-vinyl acetate copolymer, polyester, polyurethane, chlorinated polypropylene, chlorinated polyethylene, and the like can be used. Polypropylene or the like is desirable.

  The thickness of the primer layer is not limited, but is preferably about 0.1 to 10 μm, more preferably about 0.1 to 5 μm.

  Further, when the protective layer is formed of a thermoplastic resin, an adhesive resin layer may be formed between the protective layer and the second foam layer or the pattern layer in consideration of the adhesive property of the protective layer. Good. Examples of the resin contained in the adhesive resin layer include polyvinyl chloride, polyvinyl acetate, and resins obtained by polymerizing polyolefin with polar groups such as maleic anhydride and acrylic acid, and are appropriately selected depending on the layer to be bonded.

  The thickness of the adhesive resin layer is preferably about 1 to 10 μm, and more preferably about 3 to 5 μm.

  The foamed laminated sheet of the present invention may be embossed from the top surface layer. Embossing can be performed by known means such as an embossed plate. For example, when the outermost surface layer is the protective layer, a desired embossed pattern can be formed by pressing the embossed plate after heat-softening the protective layer. Examples of the embossed pattern include a wood grain plate conduit groove, a stone plate surface unevenness, a cloth surface texture, a satin texture, a grain texture, a hairline, and a multiline groove.

≪Method for producing foam sheet and foam laminated sheet≫
The method for producing a foam sheet of the present invention is not particularly limited, and is a method for producing a foam sheet having at least a first foam layer and a second foam layer,
(i) forming a foaming agent-containing resin layer by extruding or calendering the first foam layer-forming resin composition;
Step 1 of forming a second foam layer by adding a supercritical fluid to the second foam layer-forming resin composition and then foam-extruding the second foam layer-forming resin composition,
(ii) Step 2 of laminating the foaming agent-containing resin layer and the second foamed layer, and
(iii) Step 3 of obtaining the first foamed layer by foaming the foaming agent-containing resin layer,
The foamed sheet of the present invention can be preferably produced by a production method characterized by comprising

  According to the method for producing a foamed sheet of the present invention having the above characteristics, since the two specific foamed layers can be formed, a large amount of inorganic additive can be added while securing the foamed volume of the entire foamed laminated sheet. Even if it is not used, a foamed sheet useful for producing a foamed laminated sheet having excellent concealability can be obtained.

  Hereinafter, each process of the manufacturing method of a foam sheet is demonstrated. The non-foamed resin layer A and / or B may be formed on one side or both sides of the first foamed layer or the foaming agent-containing resin layer. In the description of each step below, the first foamed layer or the foaming agent-containing resin layer includes the case where the non-foamed resin layers A and / or B are formed on one side or both sides.

Process 1
In step 1, a foaming agent-containing resin layer and a second foam layer are formed. Hereinafter, formation of each layer will be described.

(Formation of foaming agent-containing resin layer)
The foaming agent-containing resin layer is formed by extruding or calendering the first foam layer-forming resin composition. Each component contained in the first foam layer forming resin composition is the same as each component described in the item of the first foam layer.

  As the extrusion molding of the first resin composition for forming a foam layer, molding by a known extrusion molding method can be employed. For example, extrusion molding using a T-die extruder, a cylindrical extruder, or the like can be given. Examples of T-die include multi-manifold type and feed block type.

  When the foaming agent-containing resin layer has a non-foamed resin layer on one side or both sides, co-extrusion with a T-die extruder is suitable. In this case, (i) the non-foamed resin layer B forming resin composition, (ii) the first foamed layer forming resin composition, and (iii) the non-foamed resin layer A forming resin composition in separate cylinders. The three resin compositions may be extruded simultaneously using a T die. The coextrusion molding by this T-die extruder is excellent in adhesiveness because each resin is melted at the time of extrusion. In addition, since the foaming agent-containing resin layer is extruded in a form sandwiched between two non-foaming resin layers, residues of additives (such as inorganic fillers) contained in the foaming agent-containing resin layer are removed from the extrusion port of the extruder ( It is difficult to generate a foreign material after film formation.

  The foaming agent-containing resin layer obtained by extrusion molding may be directly laminated on the substrate or the back surface of the second foamed layer, or may be cooled once and wound up.

  As the calendar molding of the first foam layer forming resin composition, molding by a known calendar molding method can be employed. For example, a film-like foaming agent-containing resin layer is formed by supplying and heating and pressing the first foam layer-forming resin composition between a pair of heated calender rolls. The foaming agent-containing resin layer obtained by calendering can be cooled and wound up.

(Formation of second foam layer)
The second foamed layer is formed by adding a supercritical fluid to the second foamed layer forming resin composition and then foaming and extruding the second foamed layer forming resin composition. Each component contained in the second foam layer-forming resin composition is the same as each component described in the item of the second foam layer.

  In the foam extrusion molding, a supercritical fluid is injected into a cylinder of an extruder containing the second foam layer forming resin composition and then extruded. At the stage where the second foam layer forming resin composition into which the supercritical fluid has been injected is extruded from an extruder (for example, discharged from a die of a T-die extruder), foaming of the extruded sheet has started.

  As the supercritical fluid, supercritical water, supercritical nitrogen, supercritical carbon dioxide, or the like can be used. By injecting the supercritical fluid into the second foam layer forming resin composition, a resin composition in which the supercritical fluid is dissolved in the resin is obtained. Among supercritical fluids, carbon dioxide is supercritical at 31.1 ° C. and 7.4 MPa or higher, and is therefore relatively easy to handle. Therefore, it is preferable to use supercritical carbon dioxide.

The injection amount of the supercritical fluid can be set from the viewpoint of the expansion ratio, and the injection amount is set so that the expansion ratio is 2 times or more, preferably about 2 to 10 times. For example, the supercritical fluid is preferably about 3 to 8 parts by mass with respect to 100 parts by mass of the resin component. In addition, said "foaming ratio" is the following procedures (1) to (4):
(1) Measure or calculate the weight G ′ of the resin component per unit area of the second foam layer
(2) Next, measure the thickness T ₂ ^′ of the second foam layer,
(3) Next, from the T ₂ ^′ , the weight G of the resin component per unit area in the case where the thickness is T ₂ ^′ without foaming the second foam layer,
(4) Then calculate G ÷ G '.
Thus, the expansion ratio of the second foam layer is calculated.

  The opening degree of the die opening in the foam extrusion molding machine is preferably about 100 to 800 μm. The second foam layer-forming resin composition foams at the moment when it is pushed out of the die and spreads out from the die mouth. Thereby, the second foam layer is obtained.

Process 2
In step 2, the foaming agent-containing resin layer and the second foamed layer are laminated. As a method of laminating the foaming agent-containing resin layer and the second foaming layer, (a) a method of laminating by extrusion molding or coextrusion molding, (b) a method of laminating by thermal lamination, (c) via an adhesive And laminating methods. In the method (a), the formation of the foaming agent-containing resin layer and / or the second foam layer in step 1 and the step 2 are simultaneously performed.

  As a method of laminating by extrusion molding or coextrusion molding, a method of laminating the first foam layer forming resin composition extruded from the extruder directly on the back surface of the second foam layer, foam extrusion molding from the extruder Examples include a method of laminating the second foam layer directly on the foaming agent-containing resin layer, a method of laminating by coextrusion molding of the foaming agent-containing resin layer and the second foaming layer, and the like. In the lamination by extrusion molding or coextrusion molding, the foaming agent-containing resin layer and the second foaming layer are bonded and laminated by the heat of the resin melted at the time of extrusion.

  As a method of heat laminating, the second foamed layer obtained by foam extrusion molding is laminated on the foaming agent-containing resin layer obtained by molding and heat laminated. In the lamination by thermal lamination, the foaming agent-containing resin layer and the second foamed layer are bonded and laminated by thermocompression bonding using a laminate roll.

  As a method of laminating via an adhesive, the adhesive is applied on the foaming agent-containing resin layer obtained by molding or the second foamed layer back surface, the second obtained by molding on the coated surface The foamed layer or the foaming agent-containing resin layer is adhered and laminated. It does not specifically limit as an adhesive agent, A well-known adhesive agent (For example, a urethane type adhesive agent, an acrylic adhesive agent, etc.) can be used.

Process 3
In step 3, the first foamed layer is formed by foaming the foaming agent-containing resin layer.

  The heating conditions at the time of foaming are not limited as long as the first foamed layer is formed by the decomposition of the pyrolytic foaming agent. The heating temperature is preferably about 210 to 240 ° C., and the heating time is preferably about 20 to 80 seconds. The thickness of the first foamed layer after foaming is about 300 to 700 μm.

Before the electron beam irradiation step 3, the foaming agent-containing resin layer and the second foam layer may be irradiated with an electron beam. By irradiating the foaming agent-containing resin layer with an electron beam, the foaming agent-containing resin layer is resin-crosslinked and the melt tension is adjusted, so that the expansion ratio and the uniformity of the foamed cells can be ensured. In addition, by irradiating the second foamed layer with an electron beam, the second foamed layer is resin-crosslinked, whereby heat resistance and strength are improved. Therefore, when giving the embossing pattern by the embossing mentioned later, it is excellent in the said embossing moldability. When electron beam irradiation is performed between Step 2 and Step 3, it is preferable because resin crosslinking of the foaming agent-containing resin layer and the second foamed layer can be performed simultaneously.

  The energy of the electron beam is preferably about 150 to 250 kV, more preferably about 175 to 200 kV. The irradiation amount is preferably about 10 to 100 kGy, and more preferably about 10 to 50 kGy. A known electron beam irradiation apparatus can be used as the electron beam source. In addition, this electron beam irradiation may be after forming the pattern layer or the surface protective layer.

After excision and reuse step 2 of the foaming agent-containing resin layer and the second foaming layer, both ends of the foaming agent-containing resin layer and the second foaming layer are excised, and both the excised ends are treated as step 1. May be reused as part of the first foam layer-forming resin composition and / or the second foam layer-forming resin composition. Specifically, when Step 1 to Step 3 of the present invention are continuously repeated, the slit waste cut after Step 2 is used as the first foam layer forming resin composition of Step 1 and / or Reuse as part of the second foam layer-forming resin composition. Thereby, the cost reduction in manufacture of a foam sheet and a foam lamination sheet can be aimed at.

  When the electron beam irradiation is performed before step 3, it is preferable that the both ends of the foaming agent-containing resin layer and the second foam layer are excised before the electron beam irradiation. In this case, the slit waste obtained by cutting off both ends of the foaming agent-containing resin layer and the second foamed layer is not resin-crosslinked, and therefore easily melts again. Further, as described above, the second foam layer can ensure concealment without using a pigment and can be reused.

After the embossing step 3, an embossed pattern may be appropriately added by the above-described embossing. Embossing can be performed by known means such as pressing an embossed plate. For example, a desired embossed pattern can be formed by pressing the embossed plate after heat softening the second foam layer.

Lamination of the substrate At any time, the substrate may be laminated on the back surface of the foaming agent-containing resin layer or the first foam layer. In the case of laminating the base material at the time of Step 1 or between Step 1 and Step 2, before performing Step 2, a sheet in which a foaming agent-containing resin layer is laminated on the base material and a second foam layer sheet Is obtained. When the base material is laminated between Step 2 and Step 3, before performing Step 3, a sheet in which the foaming agent-containing resin layer and the second foam layer are laminated in that order on the base material is obtained. . When the substrate is laminated after step 3, a foamed laminated sheet is obtained in which the first foamed layer and the second foamed layer are laminated in this order on the substrate. In the case where the both ends of the foaming agent-containing resin layer and the second foamed layer are excised, the base material is preferably laminated after the excision.

  As a method of laminating the base material after step 1, the foam sheet containing the foaming agent-containing resin layer and the second foam layer, or the foam sheet containing the first foam layer and the second foam layer, A method of heat laminating on a base material is mentioned. Examples of the step of laminating the base material in the step 1 include a method of extruding a foaming agent-containing resin layer on the base material.

Lamination of the pattern layer and the protective layer At any time, the pattern layer and / or the protective layer may be laminated on the second foam layer. In particular, it is preferable to laminate before step 3. About the formation method of a pattern pattern layer and / or a protective layer, it can laminate | stack by the method demonstrated by the item of the said pattern pattern layer and a protective layer.

  The foamed laminated sheet of the present invention can be used for applications such as foamed wallpaper, a laminated decorative skin material, a cushioning flooring material, and a heat insulating decorative material.

  Since the foamed laminated sheet of the present invention has the above two different specific foamed layers, the foamed laminated sheet is excellent in concealment without securing a foaming volume of the whole foamed laminated sheet and using a large amount of inorganic additive. The foamed sheet of the present invention is useful for the production of the foamed laminated sheet.

FIG. 1 is a schematic cross-sectional view of a foamed laminated sheet of the present invention. FIG. 2 is a schematic diagram showing a foam cell (dotted line) and its long diameter (arrow).

  The present invention will be specifically described below with reference to examples and comparative examples. However, the present invention is not limited to the examples.

Example 1
While melt-kneading the resin composition a described in Table 1 below using a twin-screw kneading extruder having a T die, the supercritical fluid carbon dioxide becomes 3 wt% with respect to the resin component at an injection pressure of 10 MPa. Thus, the resin composition a was kneaded and extruded from a T-die and simultaneously foamed. In this way, a sheet-like second foam layer (thickness 300 μm) was produced.

  Further, by foaming and laminating the foaming agent-containing resin pellets prepared by the resin composition e described in Table 1 below with a single-screw extruder having a T die to a thickness of 70 μm, (1) A foaming agent-containing resin layer for forming the first foamed layer and (2) the second foamed layer were laminated to obtain a foam sheet original fabric.

  Next, both ends of the foamed sheet original fabric composed of the bonded foaming agent-containing resin layer and the second foamed layer were slit. The slit piece was pulverized and returned to the first foamed layer forming resin composition and reused as a part.

  Next, the foam sheet original fabric and the paper are integrated by laminating the foam sheet original fabric on the paper (WK-665 KJ special paper) while heating the paper. Obtained. In addition, the foam sheet-containing resin layer was cross-linked by integrating the raw sheet for foam sheet and paper and simultaneously performing electron beam irradiation (200 KV, 50 KGy). After foaming the foaming agent-containing resin layer to 400 μm by heating the chemical foaming agent contained in the foaming agent-containing resin layer at 220 ° C. for 30 seconds, by pressing a metal roll having a grainy uneven pattern, A concavo-convex pattern was formed on the front side. This obtained the foaming lamination sheet.

Example 2
A foamed laminated sheet was obtained in the same manner as in Example 1 except that the resin composition b described in Table 1 below was used instead of the resin composition a described in Table 1 below. The thickness of the second foam layer was 400 μm.

Comparative Example 1
Instead of the resin composition a described in Table 1 below, the resin composition c described in Table 1 below was used, and carbon dioxide as a supercritical fluid was not kneaded in the resin composition c. Further, in place of the resin composition e described in Table 1 below, the resin composition f described in Table 1 below was used. For other matters, a foamed laminated sheet was obtained in the same manner as in Example 1. Note that the thickness of the second layer of Comparative Example 1 was 150 μm.

Comparative Example 2
The foaming agent-containing resin pellets prepared from the resin composition d described in Table 1 below were formed into a thickness of 100 μm using a single screw extruder having a T die, and the foaming agent-containing resin layer (single layer) Formed.

  Next, both ends of the foaming agent-containing resin layer were slit. The slit piece was pulverized, returned to the foaming agent-containing resin layer forming resin composition, and reused as a part.

  Next, foaming is performed in the same manner as in Example 1, except that the foaming agent-containing resin layer (single layer) is used in place of the foam sheet raw material and the electron beam irradiation amount is 200 KV, 30 KGy. A laminated sheet was obtained.

Comparative Example 3
Instead of the resin composition a described in Table 1 below, the resin composition d described in Table 1 below was used, and carbon dioxide as a supercritical fluid was not kneaded into the resin composition d. Further, in place of the resin composition e described in Table 1 below, the resin composition f described in Table 1 below was used. For other matters, a foamed laminated sheet was obtained in the same manner as in Example 1. Note that both the second layer formed of the resin composition d and the first layer formed of the resin composition f are foamed.

Comparative Example 4
While melt-kneading the resin composition a described in Table 1 below using a twin-screw kneading extruder having a T die, the supercritical fluid carbon dioxide becomes 3 wt% with respect to the resin component at an injection pressure of 10 MPa. Thus, the resin composition a was kneaded and extruded from a T-die and simultaneously foamed. In this way, a sheet-like second foam layer (thickness 300 μm) was produced.

  Next, both end portions of the obtained second foamed layer were slit. The slit piece was pulverized, returned to the second foam layer forming resin composition, and reused as a part.

  Next, while heating the paper (WK-665 KJ special paper), the second foam layer and the paper are integrated by laminating the sheet-like second foam layer on the paper, and at the same time, the electron beam The second foamed layer was crosslinked with resin by irradiation (200 KV, 50 KGy). Thereafter, a metal roll having a grainy uneven pattern was pressed to mold the uneven pattern on the second foam layer. This obtained the foaming lamination sheet.

The ratio of carbon dioxide (CO ₂ ) in each component and supercritical fluid in the resin composition used in each example and comparative example is shown in Table 1 below.

The layer configurations of the foamed laminated sheets of Examples 1 and 2 and Comparative Examples 1 and 3 are paper (base material), first layer, and second layer in order from the bottom. The first foam layer in Examples 1 and 2 corresponds to the first layer, and the second foam layer in Examples 1 and 2 corresponds to the second layer.
The layer structures of the foamed laminated sheets of Comparative Examples 2 and 4 are paper (base material) and foamed layer in order from the bottom. Here, in Comparative Example 2, since the foam layer is formed using the chemical foaming agent without using carbon dioxide of the supercritical fluid, the layer configuration of the foam laminated sheet of Comparative Example 2 is convenient. It can be a paper (base material) and a first foam layer (first layer). On the other hand, in Comparative Example 4, since the foamed layer is formed using carbon dioxide as a supercritical fluid, the layer configuration of the foamed laminated sheet of Comparative Example 4 is conveniently made of paper (base material) and The second foam layer (second layer) can be used.

Measurement 1 (Measurement of foam cell diameter)
The foam cell diameters in the first layer and the second layer were measured. Specifically, the cross section of the foamed laminated sheet was observed with a digital microscope VHX-100 manufactured by Keyence Corporation, and the first layer and the first layer with the thickness of the first foamed layer as vertical and the length of 1 mm as horizontal The major axis of the foam cell existing in the cross-sectional area of the two layers was measured.

Measurement 2 (Measurement of foaming ratio)
The expansion ratio of the first layer and the second layer was measured. The expansion ratio of the first layer, calculated by the thickness T ₁ of the first layer before foaming, and the first layer after the foam thickness T ₁ ^'was measured, T _1' to calculate the ÷ T ₁ did.
The expansion ratio of the second layer was calculated as follows. First, the weight G ′ of the resin component per unit area of the foamed second layer was measured or calculated. Next, the thickness T ₂ ^′ of the foamed second layer was measured. Then, the T ₂ ^'from the thickness without the second layer foaming T ^_2' was calculated weight G of the resin component per unit area in the case where the. Thereafter, the expansion ratio of the second layer was calculated by calculating G ÷ G ′.

Evaluation 1 (Concealment evaluation)
The concealability of each foamed laminated sheet was evaluated. Specifically, it was as follows. First, a white plate was placed on the front surface of each foamed laminated sheet, and color measurement was performed from above each foamed laminated sheet. Moreover, it replaced with the white board instead of the white board on the front surface of each foaming lamination sheet, and measured the color from on each said foaming lamination sheet. Thereafter, the difference between the colorimetric value obtained by overlapping the black plates and the colorimetric value obtained by overlapping the white plates was calculated, and the value was taken as ΔE. For colorimetry, SPECTROPHOTOMETER CM-3700d manufactured by Konica Minolta Co., Ltd. was used.
(Evaluation method)
○: ΔE is less than 2.5 ×: ΔE is 2.5 or more

Evaluation 2 (Embossing moldability evaluation)
The embossability of each foamed laminated sheet was evaluated. Specifically, the embossed pattern on the surface of each foamed laminated sheet was visually observed.
(Evaluation method)
○: The embossed pattern shape is clearly formed.
(Triangle | delta): The pattern shape of an embossed pattern is not shaped clearly, but is shaped sweetly.
X: The pattern shape of an embossed pattern cannot be observed clearly.

Evaluation 3 (Scratch resistance evaluation)
The scratch resistance of each foamed laminated sheet was evaluated. Specifically, it was evaluated by the surface strengthening test method established by the Wallpaper Industry Association.
(Evaluation method)
○: Grade 3 or higher ×: Grade 2 or lower

Evaluation 4 (Volume feeling evaluation)
The volume feeling of each foamed laminated sheet was evaluated. Specifically, the thickness of the foam sheet before embossing (the total thickness of the first layer and the second layer) was measured.
(Evaluation method)
○: 600 μm or more Δ: 400 μm or more and less than 600 μm ×: less than 400 μm

Evaluation 5 (extruded resin switchability evaluation)
The switchability of the extruded resin of each foamed laminated sheet was evaluated. Specifically, the raw sheet for foamed sheets not foamed by heat foaming was remelted and kneaded, formed into a 150 μm thick sheet, and the total light transmittance was measured and evaluated. For the measurement of total light transmittance, DIRECT READING HAZE METER manufactured by Toyo Seiki Seisakusho Co., Ltd. was used based on JIS K7361.
(Evaluation method)
○: 70% or more ×: less than 70%

  Table 2 below shows the measurement results, the evaluation results, and the calculated ratio of the number of foam cells having a major axis of 100 μm or more.

* 1: In Comparative Example 1, neither the supercritical fluid carbon dioxide nor the chemical foaming agent is used for the second layer, so the second layer is not foamed. For this reason, there is no foam cell in the second layer of Comparative Example 1.
* 2: In Comparative Examples 1 and 3, the titanium dioxide contained in the second layer inhibits the resin crosslinking of the first layer by electron beam irradiation. Therefore, the first layer of Comparative Examples 1 and 3 cannot obtain an appropriate melt tension, foam cell collapse occurs, and the foam cell diameter and expansion ratio in the first layer cannot be measured.
* 3: In Comparative Example 2, the second layer is not formed. In Comparative Example 4, the first layer is not formed.

1.Base material
2. First foam layer
3. Second foam layer
4. Foam cell
5.Long diameter of foam cell

Claims (4)

A foam sheet having at least a first foam layer and a second foam layer,
(1) In the first foam layer, the number of foam cells having a major axis of 100 μm or more is 50% or more of the total number of foam cells constituting the first foam layer,
(2) In the second foam layer, the number of foam cells having a major axis of less than 100 μm is 50% or more of the total number of foam cells constituting the second foam layer,
(3) The first foam layer is obtained by foaming a foaming agent-containing resin layer,
The blowing agent remelted and kneaded containing resin layer and the second foamed layer state, and are the total light transmittance of the resin composition was molded to 150μm thick sheet is 70% or more,
(4) The thickness of the first foam layer is 300 to 700 μm.
A foamed sheet characterized by the above. A foam laminated sheet in which a first foam layer and a second foam layer are laminated in order on a substrate,
(1) In the first foam layer, the number of foam cells having a major axis of 100 μm or more is 50% or more of the total number of foam cells constituting the first foam layer,
(2) In the second foam layer, the number of foam cells having a major axis of less than 100 μm is 50% or more of the total number of foam cells constituting the second foam layer,
(3) The first foam layer is obtained by foaming a foaming agent-containing resin layer,
The blowing agent remelted and kneaded containing resin layer and the second foamed layer state, and are the total light transmittance of the resin composition was molded to 150μm thick sheet is 70% or more,
(4) The thickness of the first foam layer is 300 to 700 μm.
A foamed laminated sheet characterized by that.   The said 1st foaming layer is a foaming lamination sheet of Claim 2 obtained by foaming the foaming agent containing resin layer resin-crosslinked by electron beam irradiation.   The foamed laminated sheet according to claim 2 or 3, wherein the second foamed layer is resin-crosslinked by electron beam irradiation.

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