JP5640607B2 - Laminated sheet and foam laminated sheet - Google Patents

Description

  The present invention relates to a laminated sheet and a foam laminated sheet.

  Conventionally, a foamed laminated sheet is known in which a foamed resin layer of vinyl chloride resin is formed on a base material (for example, backing paper). In recent years, in consideration of the environment, resins that do not contain halogen such as ethylene-vinyl acetate copolymer resin (EVA), acrylic resin, and olefin resin have been used for the foamed resin layer. The foamed resin layer is generally obtained by forming a foaming agent-containing resin layer on a substrate and then foaming the foaming agent-containing resin layer by heating. Examples of the method for forming the foaming agent-containing resin layer include a calendar method, an extrusion method using a T-die, and a method of applying a resin emulsion.

  Here, for the purpose of imparting flame retardancy to the foamed laminated sheet, reducing the amount of the resin component contained in the foaming agent-containing resin layer, etc., the laminated sheet before foaming (hereinafter also simply referred to as a laminated sheet) Inexpensive heavy calcium carbonate is used as the inorganic filler contained in the foaming agent-containing resin layer (Patent Document 1).

JP 2006-102950 A

  However, when the foaming agent-containing resin layer containing heavy calcium carbonate is crosslinked by electron beam irradiation for the purpose of increasing the melt tension and adjusting the expansion ratio, the foaming agent-containing resin layer is discolored. However, there is a problem that the design cannot be expressed when a foamed laminated sheet is used.

  Therefore, the development of a laminated sheet having at least a foaming agent-containing resin layer on a substrate, the inorganic foaming agent being contained in the foaming agent-containing resin layer, and discoloration suppressed even after electron beam crosslinking has been developed. It is desired.

  The present invention is a laminated sheet having at least a foaming agent-containing resin layer on a substrate, wherein the foaming agent-containing resin layer contains an inorganic filler, and discoloration is suppressed even after electron beam crosslinking, And it aims at providing the foaming lamination sheet by which discoloration was suppressed.

  As a result of intensive studies, the present inventor has found that the object can be achieved by containing a specific amount of a specific inorganic filler in the foaming agent-containing resin layer, and has completed the present invention.

That is, the present invention relates to the following laminated sheet and foamed laminated sheet.
1. A laminated sheet having at least a foaming agent-containing resin layer on a substrate,
(1) The foaming agent-containing resin layer contains light calcium carbonate and heavy calcium carbonate as essential components, and 25 parts by weight of light calcium carbonate having an average particle size of 16 μm or less with respect to 100 parts by weight of the resin component. And the content of heavy calcium carbonate with respect to 100 parts by weight of the resin component is less than 20 parts by weight,
(2) The foaming agent-containing resin layer is electron beam cross-linked,
A laminated sheet characterized by that.
2. The said foaming agent containing resin layer is a lamination sheet of said claim | item 1 containing at least 1 sort (s) chosen from the group which consists of polyethylene and an ethylene copolymer as a resin component.
3. Item 3. The laminated sheet according to Item 1 or 2, wherein a non-foamed resin layer A is formed on the foaming agent-containing resin layer.
4). Item 4. The laminated sheet according to any one of Items 1 to 3, wherein a non-foamed resin layer B is formed between the base material and the foaming agent-containing resin layer.
5. The foaming lamination sheet obtained by heat-foaming the lamination sheet in any one of said items 1-4.
6). Item 6. The foamed laminated sheet according to Item 5, wherein the substrate is a fibrous sheet.

  Hereinafter, the laminated sheet and the foamed laminated sheet of the present invention will be described in detail.

Laminated sheet The laminated sheet of the present invention is a laminated sheet having at least a foaming agent-containing resin layer on a substrate,
(1) The foaming agent-containing resin layer contains 25 parts by weight or more of light calcium carbonate having an average particle size of 16 μm or less with respect to 100 parts by weight of the resin component, and
The content of heavy calcium carbonate with respect to the resin component is less than 20 parts by weight,
(2) The foaming agent-containing resin layer is electron beam cross-linked.

  Since the said laminated sheet contains light calcium carbonate in the foaming agent containing resin layer, it is excellent in resin film formability, providing a flame retardance, and also discoloration is suppressed after electron beam bridge | crosslinking. Moreover, discoloration of the foamed laminated sheet obtained by foaming the foaming agent-containing resin layer of the laminated sheet is suppressed.

  The configuration of the laminated sheet of the present invention is not limited, and may be a laminated sheet having at least a foaming agent-containing resin layer on a substrate. Examples thereof include a laminated sheet in which a non-foamed resin layer B, a foaming agent-containing resin layer, a non-foamed resin layer A, a design pattern layer, and a surface protective layer are laminated in this order on a substrate. Hereinafter, each layer constituting the laminated sheet will be described as a representative example.

The base material is not particularly limited as long as it has mechanical strength, heat resistance and the like suitable as the base material of the laminated sheet, and is, for example, a resin sheet, a fibrous sheet (for example, paper, non-woven fabric, etc .; simply referred to as fibrous). ) Etc. can generally be used.

  Of these, fiber sheets such as paper are preferable. Specifically, flame retardant paper (pulp-based sheets treated with flame retardants such as guanidine sulfamate and guanidine phosphate); aluminum hydroxide, magnesium hydroxide Inorganic paper containing inorganic additives such as: high-quality paper; thin paper.

Although the basis weight of the substrate is not critical, preferably about 50 to 300 g / ^{m 2,} about 50 to 80 g / ^{m 2} is more preferable.

Non-foamed resin layer B
In the present invention, a non-foamed resin layer (non-foamed resin layer B) may be formed between the substrate and the foamed resin layer as necessary. In particular, when the non-foamed resin layer B is formed as an adhesive layer, excellent adhesion between the substrate and the foamed resin layer can be obtained.

  As the non-foamed resin layer B, for example, ethylene-vinyl acetate copolymer (EVA) or the like can be suitably used. The non-foamed resin layer B may contain known additives in addition to the resin component, but is preferably blended so that the content of the resin component is 70 to 100% by weight.

  The thickness of the non-foamed resin layer B is not limited, but is preferably about 5 to 50 μm, more preferably about 5 to 15 μm.

In the present invention, the foaming agent-containing resin layer contains at least a resin component, light calcium carbonate having an average particle size of 16 μm or less, and a foaming agent.

  The resin component contains at least one selected from the group consisting of polyethylene and ethylene copolymers having monomers other than ethylene and ethylene (hereinafter abbreviated as “ethylene copolymer”). Is preferred.

  Polyethylene and ethylene copolymers are suitable for extrusion film formation in terms of melting point and MFR. Examples of the ethylene copolymer include ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate copolymer ( EMA), ethylene- (meth) acrylic acid copolymer (EMAA), ethylene-α olefin copolymer, and the like. These ethylene copolymers can be used alone or in admixture of two or more.

  In particular, it is preferable to contain any one of an ethylene-vinyl acetate copolymer, an ethylene-methyl methacrylate copolymer, and a mixture of polyethylene and an ethylene-α-olefin copolymer. When the resin component contains a mixture of polyethylene and an ethylene-α-olefin copolymer, the content of the ethylene-α-olefin copolymer is preferably 50% by weight or more.

  When any one of ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, and a mixture of polyethylene and ethylene-α-olefin copolymer is used in combination with one or more other resins, The content of any one kind of resin component is preferably 70% by weight or more, and more preferably 80% by weight or more.

  The MFR of the polyethylene or ethylene copolymer is preferably 9 to 70 g / 10 minutes, and more preferably 9 to 20 g / 10 minutes. By adopting such MFR, the extrusion film forming property is further enhanced. In addition, MFR of this specification is the value measured by the test method of JISK7210 (flow test method of thermoplastics). As test conditions, “190 ° C., 21.18 N (2.16 kgf)” described in JIS K 6760 is adopted.

  Moreover, 5-30 weight% is preferable as an ethylene copolymer content of monomers other than ethylene, and 9-20 weight% is more preferable. By adopting such a copolymerization ratio, the extrusion film forming property is further enhanced. As a specific example, the ethylene-vinyl acetate copolymer has a vinyl acetate copolymerization ratio (VA amount) of preferably 9 to 25% by weight, more preferably 9 to 20% by weight. Moreover, 5-25 weight% is preferable as a copolymerization ratio (MMA amount) of a methylmethacrylate, and, as for the ethylene-methylmethacrylate copolymer, 5-15 weight% is more preferable.

  The foaming agent can be selected from known foaming agents. For example, azo type such as azodicarbonamide (ADCA) and azobisformamide; organic thermal decomposition type foaming agent such as hydrazide type such as oxybenzenesulfonyl hydrazide (OBSH) and paratoluenesulfonyl hydrazide, microcapsule type foaming agent, Examples include inorganic foaming agents such as baking soda. The content of the foaming agent is set according to the type of foaming agent and the expansion ratio. In the present invention, the expansion ratio is 5 times or more, preferably about 6.5 to 10 times. The foaming agent is preferably about 1 to 10 parts by weight with respect to 100 parts by weight of the resin component.

  In the present invention, the foaming agent-containing resin layer contains light calcium carbonate having an average particle size of 16 μm or less. By containing the light calcium carbonate in the foaming agent-containing resin layer, while imparting flame retardancy to the foaming agent-containing resin layer, it is excellent in resin film formability, and further discoloration is suppressed even after electron beam crosslinking. The

  The light calcium carbonate in the present invention refers to calcium carbonate (synthetic product) that is chemically produced from (dense) limestone as a raw material, and is a naturally occurring weathered oyster shell, marine microbial shell deposit, sugar It is distinguished from heavy calcium carbonate (natural product) produced by dry or wet grinding of crystal limestone.

  What is marketed can be used for the said light calcium carbonate in this invention. For example, trade name: PC (manufactured by Shiroishi Kogyo Co., Ltd.), trade name: Brilliant-15 (manufactured by Shiroishi Kogyo Co., Ltd.) and the like can be used.

  Moreover, the said light calcium carbonate can be manufactured by a well-known method (for example, carbon dioxide compounding method). The carbon dioxide compound method is a calcium hydroxide suspension (lime milk) produced by calcining (dense) limestone at about 1000 ° C. to decompose quicklime and carbon dioxide, and reacting this quicklime with water. ), Carbon dioxide gas generated during firing is introduced and reacted to form and precipitate calcium carbonate, which is dehydrated and dried to produce a product.

  Light calcium carbonate having an average particle size of 16 μm or less is used. A preferable average particle diameter is 7 micrometers or less, More preferably, it is 0.02-3.2 micrometers. The average particle diameter in the present invention refers to the mode diameter (maximum value of particle diameter distribution (frequency distribution)). The average particle diameter can be measured using a laser diffraction scattering method. When the particle size is in the above range, even when the thickness of the foaming agent-containing resin layer is thinly extruded (particularly less than 90 μm), the resin hardly breaks down and can be formed at high speed.

  The light calcium carbonate content may be 25 parts by weight or more with respect to 100 parts by weight of the resin component, and the preferred content is 100 parts by weight or less with respect to 100 parts by weight of the resin component. From the viewpoint of foam volume, the upper limit of the content is more preferably 80 parts by weight.

  The shape of light calcium carbonate is not limited, but the primary particles such as cubes, spindles, needles (or rods), plates, fine cubes and needles are loosened and agglomerated into algae. Examples include coalescence.

  In the present invention, heavy calcium carbonate may be used in combination under the condition of less than 20 parts by weight per 100 parts by weight of the resin component. By adding heavy calcium carbonate within the above range, the machinability and flame retardancy of the foamed laminated sheet are improved. However, when heavy calcium carbonate is used in an amount of 20 parts by weight or more with respect to 100 parts by weight of the resin component, discoloration of the foaming agent-containing resin layer is remarkable when crosslinking is performed by electron beam irradiation, and in particular, a particle size of less than 20 μm. When many are included, the tendency becomes remarkable, which is not preferable.

  Other inorganic fillers may be used in the foaming agent-containing resin layer as long as the effects of the present invention are not affected. Examples thereof include aluminum hydroxide and magnesium hydroxide. Although content of the said inorganic filler is not specifically limited, What is necessary is just to be about 1-20 weight part with respect to 100 weight part of resin components.

  An additive may be added to the foaming agent-containing resin layer as long as the effect of the present invention is not affected. For example, pigments, foam stabilizers, antioxidants, foaming aids (zinc compounds), crosslinking agents, surface treatment agents, fluorescent whitening agents, fungicides, lubricants, and the like can be used as additives.

  As for pigments, 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 Inorganic pigments such as ultramarine, bituminous, cobalt blue, chromium oxide, cobalt green, aluminum powder, bronze powder, titanium mica, zinc sulfide; for example, 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, indanthro , And organic pigments halogenated phthalocyanine), or the like. About 10-50 weight part is preferable with respect to 100 weight part of resin components, and, as for content of a pigment, about 15-40 weight part is more preferable.

  Examples of the foam stabilizer include alkyl sulfonate and alkyl benzene sulfonate. Specifically, at least one of sodium dodecylbenzenesulfonate and calcium dodecylbenzenesulfonate is preferable.

  Further, a metal soap such as zinc stearate and a surfactant can be used. These contents are preferably about 0.3 to 10 parts by weight, and more preferably about 1 to 5 parts by weight with respect to 100 parts by weight of the resin component.

  Examples of the antioxidant include 2,6-ditert-butyl-p-cresol and tetrakis [methylene-3 (3,5-di-tert-butyl-4-hydroxy-phenyl), which are phenolic antioxidants. Propionate] methane, phosphorous antioxidant tris (2,4-di-butylphenyl) phosphite, distearyl pentaerythritol diphosphite and the like.

  Examples of the foaming aid include zinc oxide, hydroxide, carbonate, basic carbonate, sulfate, nitrate, phosphite, carboxylate and the like. Such a zinc compound is preferably added from the viewpoint of improving the foaming speed. Examples of the carboxylate include acetic acid, propionic acid, 2-ethylhexanoic acid, nonanoic acid, isononanoic acid, isodecanoic acid, neodecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, oleic acid, Examples include aliphatic acids such as 12-hydroxystearic acid, ricinoleic acid, and behenic acid, and aromatic acids such as benzoic acid, p-tert-butylbenzoic acid, toluic acid, salicylic acid, and naphthenic acid. The zinc carboxylate using these carboxylic acids may be in the form of a normal salt, an acid salt, or a basic salt. The above-mentioned carboxylic acids constituting the zinc carboxylate can be used, but from the viewpoint of reducing VOC, those which are powders at room temperature using fatty acids having 12 or more carbon atoms, such as zinc stearate Zinc laurate and the like are preferable. When other carboxylic acid is used, it may be liquid or may need to be dissolved in an organic solvent in order to improve handling properties.

  The content of the zinc compound is preferably about 0.001 to 20 parts by weight and more preferably about 0.001 to 10 parts by weight with respect to 100 parts by weight of the resin component.

  Although the thickness of a foaming agent containing resin layer is not limited, it is about 40-100 micrometers in a non-foaming state (before foaming), and 50-70 micrometers is more preferable. 400-700 micrometers is preferable after foaming.

  What is necessary is just to implement according to the method described in the manufacturing method of the postscript as a method of foaming a foaming agent containing resin layer.

Non-foamed resin layer A
A non-foamed resin layer A may be further formed on the front surface of the foaming agent-containing resin layer.

  The non-foamed resin layer A mainly protects the foaming agent-containing resin layer.

  The resin component contained in the non-foamed resin layer A is not particularly limited, and for example, polyethylene, an ethylene copolymer, an ionomer resin, or the like can be used. Examples of the ethylene copolymer include ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), and ethylene-methyl acrylate copolymer (EMA). ), Ethylene- (meth) acrylic acid copolymer (EMAA), ethylene-α olefin copolymer, and the like. These resin components can be used alone or in admixture of two or more.

In order to obtain particularly excellent scratch resistance and abrasion resistance, the resin component is at least one of acrylic acid (CH ₂ ═CHCOOH) and methacrylic acid (CH ₂ ═C (CH ₃ ) COOH). A copolymer obtained by a combination of a monomer and ethylene can be suitably used as a resin component. More specifically, it is desirable to use at least one of an ethylene- (meth) acrylic acid copolymer and an ionomer resin. As the ionomer resin, a resin having a structure in which the molecules of the ethylene- (meth) acrylic acid copolymer are intermolecularly bonded with metal ions such as sodium and zinc can be used. When such a resin component is used, it is possible to form a strong layer caused by hydrogen bonds in the resin. In addition, these can use a well-known or commercially available thing.

  The content of acrylic acid or methacrylic acid in the copolymer is not limited, but is preferably 15% by weight or less, more preferably about 4 to 15% by weight. Such a resin can also use a commercial item. A known additive can also be blended in the resin composition.

  The thickness of the non-foamed resin layer A is not limited, but is preferably about 5 to 50 μm, more preferably about 8 to 20 μm.

  Although the melt flow rate value of the resin component depends on the type of the resin component to be used, etc., it is generally set as appropriate within a range of 10 g / 10 min or more. Usually, it is preferably 10 to 100 g / 10 minutes, particularly preferably 10 to 95 g / 10 minutes, and more preferably 20 to 80 g / 10 minutes. By using a material having such a numerical range, more excellent scratch resistance, wear resistance and the like can be obtained.

  Moreover, although content of the said resin component in a resin composition is not limited, Usually, it is preferable to set suitably in the range of 70 to 100 weight%.

Pattern Pattern Layer In the present invention, a pattern pattern layer may be provided on the foaming agent-containing resin layer (when the non-foamed resin layer A is provided).

  The design 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. The pattern can be selected according to the type of the (foamed) laminated sheet.

  The pattern pattern layer can be formed, for example, by printing a pattern pattern on the front surface of the non-foamed resin layer A. In addition, when forming a pattern layer, a primer layer may be formed in advance as necessary, or the surface of the non-foamed resin layer A may be subjected to corona discharge treatment. The corona discharge treatment can be performed according to a known method.

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

  As the colorant, for example, a pigment used in the above-described foaming agent-containing resin layer can be appropriately used.

  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, 2-methoxyethyl acetate, and 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; ether organic solvents such as diethyl ether, dioxane, tetrahydrofuran; dichloromethane, carbon tetrachloride, trichloroethylene, tetrachloroethylene, etc. Chlorinated organic solvents; and water.

  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.

Surface protective layer (overcoat layer)
In the present invention, a surface protective layer may be provided on the surface of the design pattern layer for the purpose of adjusting the gloss and / or protecting the design pattern layer. The kind of surface protective layer is not limited. If it is a surface protective layer aiming at gloss adjustment, there exists a surface protective layer containing known fillers, such as a silica, for example. As a method for forming the surface protective layer, a known method such as gravure printing can be employed. In addition, when the adhesiveness of a pattern pattern layer and a surface protective layer is not fully acquired, a surface protective layer can also be provided after carrying out the adhesion process (primer process) of the surface of a pattern pattern layer.

  When forming a surface protective layer for the purpose of surface strength (scratch resistance, etc.), contamination resistance, pattern layer protection, etc. of foamed laminated sheets, those containing ionizing radiation curable resins as resin components are suitable It is. The ionizing radiation curable resin is preferably one that undergoes radical polymerization (curing) by electron beam irradiation.

  The thickness of the surface protective layer is not limited, but is preferably about 0.1 to 15 μm.

Embossing In this invention, you may attach | subject an embossing pattern suitably. In this case, what is necessary is just to emboss from the uppermost surface layer (opposite side of a base material) of a (foaming) laminated sheet. Embossing can be performed by known means such as pressing an embossed plate. For example, when the outermost surface layer is a surface protective layer, a desired embossed pattern can be formed by pressing the embossed plate after heat-softening the front surface. 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 laminated sheet>
The manufacturing method of a foam lamination sheet is not specifically limited. For example, a foamed laminated sheet having a foamed resin layer and a non-foamed resin layer A on a substrate is formed by forming a foaming agent-containing resin layer and a non-foamed resin layer A on a substrate by simultaneous melt extrusion, and then laminating the sheet. After obtaining, an electron beam is irradiated from the front side of the foaming agent-containing resin layer, and then the foaming agent-containing resin layer is foamed by heating.

  For simultaneous melt extrusion, a multi-manifold type T-die capable of simultaneously forming a plurality of layers can be used. In this case, the resin composition for forming the foaming agent-containing resin layer and the resin composition for forming the non-foamed resin layer may be placed in separate cylinders, and multiple layers may be simultaneously extruded to form and laminate. . In addition, since the foaming agent-containing resin layer contains an inorganic filler, when the foaming agent-containing resin layer is formed by extrusion molding, an inorganic filler residue (so-called eyes or nibs) is formed at the extrusion port (so-called die) of the extrusion molding machine. ) Are likely to occur, and this tends to be a foreign matter on the sheet surface. Therefore, it is preferable to co-extrusion the non-foamed resin layer B together with the foaming agent-containing resin layer in addition to the non-foamed resin layer A. Thus, by simultaneously extruding and molding the foaming agent-containing resin layer between the non-foamed resin layers, it is possible to suppress the occurrence of the eyes. Moreover, since the resin layer laminated | stacked on the base material simultaneously with extrusion has adhesiveness by heat melting, it adhere | attaches with a base material.

  Alternatively, a laminate in which multiple layers are simultaneously formed may be prepared, placed on the substrate, and bonded to the substrate by thermal lamination.

  The electron beam irradiation is performed before the heat treatment. Thereby, since a resin component can be bridge | crosslinked, the surface strength of a foaming lamination sheet, the foaming degree, etc. can be controlled. The energy of the electron beam is preferably about 150 to 250 kV. The irradiation amount is preferably about 1 to 7 Mrad. A known electron beam irradiation apparatus can be used as the electron beam source.

  The crosslinking of the resin component can also be carried out using a chemical crosslinking agent (also referred to as a crosslinking agent or a crosslinking aid). Examples thereof include polyfunctional monomers such as neopentyl glycol dimethacrylate and trimethylolpropane trimethacrylate, oligomers, and the like. The crosslinking agent is preferably about 0 to 10 parts by weight, more preferably 1 to 4 parts by weight with respect to 100 parts by weight of the resin component. In addition, it is also possible to promote the bridge | crosslinking by electron beam irradiation by using electron beam irradiation and the said crosslinking agent together.

  In addition, you may form a pattern pattern layer and a surface protective layer before irradiating an electron beam. The pattern pattern layer may be formed as described above. In addition, when a surface protective layer containing an ionizing radiation curable resin is formed, the surface protective layer is cured simultaneously (by the same treatment) with electron beam irradiation performed to crosslink the resin contained in the foaming agent-containing resin layer. To be efficient. That is, after forming a foaming agent-containing resin layer, a non-foaming resin layer, a pattern layer, and a surface protective layer containing an ionizing radiation curable resin in this order, the resin contained in the foaming agent-containing resin layer is irradiated with an electron beam. The resin contained in the surface protective layer can be cured while being crosslinked.

  The heating conditions are not limited as long as the foamed resin layer is formed by the decomposition of the foaming agent. The heating temperature is about 200 to 220 ° C., and the heating time is about 30 to 45 seconds. Moreover, you may emboss the obtained foaming laminated sheet.

  The foamed laminated sheet can be used for applications such as foamed wallpaper, laminated skin material, cushioning flooring material, and heat-insulating cosmetic material.

  Since the laminated sheet of the present invention contains light calcium carbonate in the foaming agent-containing resin layer, it is excellent in resin film-forming properties while imparting flame retardancy, and further discoloration is suppressed even after electron beam crosslinking. . Moreover, discoloration of the foamed laminated sheet obtained by foaming the foaming agent-containing resin layer of the laminated sheet is suppressed.

  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
Using a three-type three-layer multi-manifold T-die extruder, a paper-based substrate (backing paper) so that the thickness is 10 μm / 70 μm / 10 μm in the order of non-foamed resin layer A / foaming agent-containing resin layer / non-foamed resin layer B To form a film. Thereby, the laminated body which consists of non-foaming resin layer A / foaming agent containing resin layer / non-foaming resin layer B / paper-type base material was obtained.

  As a base material, backing paper “WK-665DO (manufactured by Kojin Co., Ltd.)” was prepared, heated to 90 ° C., and then the above three layers were extruded to form a film.

  Extrusion conditions were such that the cylinder temperature containing the resin for forming the non-foamed resin layer A was 140 ° C., the cylinder temperature containing the resin composition for forming the foaming agent-containing resin layer was 120 ° C., and non-foamed The cylinder temperature in which the resin for forming the resin layer B was accommodated was 100 ° C. The die temperature was 120 ° C. for all.

  The laminate was irradiated with an electron beam (195 kV, 30 KGy) from the non-foamed resin layer A side, and in particular, the foaming agent-containing resin layer was resin-crosslinked. Further, a corona discharge treatment was performed on the non-foamed resin layer A.

  Next, a texture pattern was printed on the non-foamed resin layer A by gravure printing using a water-based ink “Hydric” (manufactured by Dainichi Seika Kogyo Co., Ltd.) to obtain a laminated sheet.

  Next, the laminated sheet on which the fabric pattern was printed was heated in a gear oven (at 220 ° C. for 35 seconds) to foam the foaming agent-containing resin layer.

  Finally, the foam was embossed with a texture pattern to obtain a foam laminated sheet.

  Each layer was formed using the following components.

  The non-foamed resin layer A was formed of an ethylene- (meth) acrylic acid copolymer “Nucleel N1560 (MAA content: 15% by weight), manufactured by Mitsui DuPont Polychemical Co., Ltd.”.

The foaming agent-containing resin layer
EVA "Ultrasen 633 (VA content: 20% by weight), manufactured by Tosoh Corporation" 100 parts by weight,
4 parts by weight of foaming agent “Uniform Ultra AZ3050 Otsuka Chemical Co., Ltd.”
Light calcium carbonate “PC, average particle size: 3.2 μm, manufactured by Shiroishi Kogyo Co., Ltd.” 80 parts by weight,
20 parts by weight of titanium dioxide “Tai Pure R-350, manufactured by DuPont”
4 parts by weight of a foaming aid “MFX-50J-3, manufactured by Daikyo Kasei Kogyo Co., Ltd.”
It was formed with 1 part by weight of a crosslinking aid “OPSTAR JUA702, manufactured by JSR Corporation”.

  The non-foamed resin layer B was formed by EVA “Ultrasen 750 (VA content: 32% by weight), manufactured by Tosoh Corporation”.

  The expansion ratio of the foamed resin layer was 7 times.

Example 2
The non-foamed resin layer A was formed of low-density polyethylene “Petrocene 202, manufactured by Tosoh Corporation”.

The foaming agent-containing resin layer
50 parts by weight of low density polyethylene “Petrocene 208, manufactured by Tosoh Corporation”
50 parts by weight of ultra-low density polyethylene “LUMITAC 54-1 manufactured by Tosoh Corporation”
4 parts by weight of foaming agent “Uniform Ultra AZ3050 Otsuka Chemical Co., Ltd.”
Light calcium carbonate “Brilliant-15, average particle size: 0.15 μm, manufactured by Shiroishi Kogyo Co., Ltd.” 40 parts by weight,
30 parts by weight of titanium dioxide “Tai Pure R-108, DuPont Co., Ltd.”
Foaming aid “ADK STAB OF-101, manufactured by ADEKA Corporation” 5 parts by weight,
It was formed with 1 part by weight of a crosslinking aid “OPSTAR JUA702, manufactured by JSR Corporation”.

  Conditions other than the above were the same as in Example 1, and a laminated sheet and a foamed laminated sheet were produced.

  The expansion ratio of the foamed resin layer was 6.5 times.

Example 3
Instead of 40 parts by weight of light calcium carbonate “Brillant-15, manufactured by Shiroishi Kogyo Co., Ltd.”, 25 parts by weight of light calcium carbonate “Brilliant-15, manufactured by Shiroishi Kogyo Co., Ltd.” and heavy calcium carbonate “Whiteon P- A laminated sheet and a foamed laminated sheet were obtained in the same manner as in Example 2 except that 19 parts by weight (50 (average particle size: 19 μm), manufactured by Shiraishi Kogyo Co., Ltd.) was used.

  The expansion ratio of the foamed resin layer was 6.5 times.

Comparative Example 1
Example 1 except that heavy calcium carbonate “Whiteon H (average particle size: 22 μm), manufactured by Shiraishi Kogyo Co., Ltd.” was used instead of light calcium carbonate “PC, manufactured by Shiroishi Kogyo Co., Ltd.” Thus, a laminated sheet and a foam laminated sheet were obtained.

Comparative Example 2
Example 1 except that heavy calcium carbonate “Whiteon 306 (average particle size: 12 μm), manufactured by Shiroishi Kogyo Co., Ltd.” was used instead of light calcium carbonate “PC, manufactured by Shiroishi Kogyo Co., Ltd.” Thus, a laminated sheet and a foam laminated sheet were obtained.

Comparative Example 3
Example 1 except that light calcium carbonate “PC, manufactured by Shiraishi Kogyo Co., Ltd.” was used instead of heavy calcium carbonate “Whiteon P-10 (average particle size: 3 μm), manufactured by Shiroishi Kogyo Co., Ltd.” In the same manner as above, a laminated sheet and a foamed laminated sheet were obtained.

Comparative Example 4
Implemented except using heavy calcium carbonate “Whiteon P-30 (average particle size: 4 μm), Shiraishi Kogyo Co., Ltd.” instead of light calcium carbonate “Brillant-15, Shiraishi Kogyo Co., Ltd.” In the same manner as in Example 2, a laminated sheet and a foamed laminated sheet were obtained.

Test example 1
The color difference (ΔE) viewed from the resin layer side was examined before and after electron beam irradiation of the laminated sheet and before and after heating and foaming of the foamed laminated sheet.

ΔE was calculated using equation (1) by measuring L *, a *, b * using a Minolta color difference meter (CR-300). L *, a *, and b * are measurement data, and L * _t , a * _t , and b * _t are color difference reference colors.
ΔE = √ {(L * −L * _t ) ² + (a * −a * _t ) ² + (b * −b * _t ) ² } (1)
The results are shown in Table 1 below.

Test example 2
Regarding the laminated sheets prepared in Examples and Comparative Examples, the film forming property of the foaming agent-containing resin layer was evaluated. The case where there was no in-machine foaming (early foaming in the extruder cylinder before extrusion film formation), and the film could be formed normally without cutting the resin at a take-up speed of 60 m / min, was evaluated as ○, and the take-up speed was up to 45 m / min. In this case, the case where the film could be formed without cutting the resin was evaluated as Δ, and the case where the take-up speed was up to 30 m / min was evaluated as x.

  The laminated sheets in the examples are excellent in resin film formability, and further have a color difference (ΔE) of 1.0 or less before and after electron beam irradiation, and discoloration is suppressed. Moreover, the foam lamination sheet in an Example has the color difference ((DELTA) E) before and behind heat foaming of 3.0 or less, and discoloration is suppressed.

Claims (6)

A laminated sheet having at least a foaming agent-containing resin layer on a substrate,
(1) The foaming agent-containing resin layer contains light calcium carbonate and heavy calcium carbonate as essential components, and 25 parts by weight of light calcium carbonate having an average particle size of 16 μm or less with respect to 100 parts by weight of the resin component. And the content of heavy calcium carbonate with respect to 100 parts by weight of the resin component is less than 20 parts by weight,
(2) The foaming agent-containing resin layer is electron beam cross-linked,
A laminated sheet characterized by that.   The said foaming agent containing resin layer is a laminated sheet of Claim 1 containing at least 1 sort (s) chosen from the group which consists of polyethylene and an ethylene copolymer as a resin component.   The laminated sheet according to claim 1 or 2, wherein a non-foamed resin layer A is formed on the foaming agent-containing resin layer.   The laminated sheet according to any one of claims 1 to 3, wherein a non-foamed resin layer B is formed between the base material and the foaming agent-containing resin layer.   The foaming lamination sheet obtained by heat-foaming the lamination sheet in any one of Claims 1-4.   The foaming laminated sheet of Claim 5 whose said base material is a fibrous sheet.