JP5649693B2 - Laminated body of foamed decorative sheet before foaming, foamed decorative sheet and method for producing them - Google Patents

Description

  The present invention relates to a resin composition for producing a foam and a foam using the same.

  As a foam, the foamed resin layer used for a foaming decorative sheet is mentioned, for example.

  Conventionally, a foamed decorative sheet is known in which a foamed resin layer of vinyl chloride resin is formed on a paper-based substrate (backing paper). In recent years, in consideration of the environment, resins that do not contain a halogen component such as ethylene-vinyl acetate copolymer resin (EVA), acrylic resin, and olefin resin have been used for the foamed resin layer (Patent Document 1). ~ 3 etc.).

  The foamed resin layer is obtained, for example, by heating and foaming a foaming agent-containing resin layer formed from a resin composition containing a resin component, a thermal decomposition foaming agent, and a foaming aid. Examples of the composition of the resin composition include, for example, EVA, resin components such as ethylene-methyl methacrylate copolymer (EMMA), azodicarbonamide foaming agent (ADCA foaming agent), metal oxide foaming aid, Formulation examples containing a fatty acid metal salt foaming aid (for example, zinc stearate, zinc oxide, magnesium oxide, etc.) are known.

  However, in the above blending example, when the resin component is changed to a carboxyl group-containing resin (for example, ethylene methacrylic acid copolymer: EMAA), the finally obtained foamed resin layer is discolored (yellowed) There is a problem that the paper base material is yellowed. This is because the carboxyl group-containing resin and the foaming aid (metal oxide type and fatty acid metal salt type) chemically react to impair the foaming promotion effect of the foaming aid. It is considered that the heating is necessary and the resin layer and the paper base are burnt (discolored). It is also considered that the carboxyl group-containing resin, the foaming agent, and the foaming aid form a chromophore (yellow) such as a complex to color the resin layer.

  The above-mentioned problem is a problem common to not only foamed decorative sheets but also resin compositions for foam production containing a carboxyl group-containing resin, an ADCA-based foaming agent, and a foaming aid (metal oxide-based and fatty acid metal salt-based). is there. When using a carboxyl group-containing resin (especially EMAA), since the foam surface strength is higher than when using other resins, the above problems have been improved by devising the type of foaming aid. It is desired to develop a resin composition for foam production and a foam.

Japanese Patent Laid-Open No. 6-47875 JP 2000-255011 A JP 2001-347611 A

  The present invention relates to a resin composition for foam production comprising a carboxyl group-containing resin and an ADCA-based foaming agent, and a foam with improved problems such as discoloration (yellowing) of the foam obtained by heating and foaming. It aims at providing the resin composition for manufacture. Moreover, it aims also at providing the foam obtained using the said resin composition for foam manufacture.

  As a result of intensive studies, the present inventor has found that the above object can be achieved when a specific compound is used as a foaming aid, and has completed the present invention.

That is, the present invention relates to the following resin composition for foam production and foam.
1. A resin composition for producing a foam, which comprises a resin containing a carboxyl group, an azodicarbonamide-based foaming agent, and a carboxylic acid hydrazide compound.
2. Item 2. The item 1, wherein the carboxyl group-containing resin is at least one selected from the group consisting of ethylene-methacrylic acid copolymers, ethylene-acrylic acid copolymers, and ionomers containing these copolymers. Resin composition for foam production.
3. Item 2. The resin composition for foam production according to Item 1, wherein the carboxyl group-containing resin is an ethylene-methacrylic acid copolymer.
4). Item 4. The resin composition for foam production according to any one of Items 1 to 3, wherein the carboxylic acid hydrazide compound is adipic acid dihydrazide.
5. The foam obtained by heat-foaming after shape | molding the resin composition for foam manufacture in any one of said claim | item 1-4 to a desired shape.
6). The foamed resin layer obtained by heat-foaming after shape | molding the resin composition for foam manufacture in any one of said claim | item 1-4 to a sheet form.
7). Item 7. A foamed decorative sheet having at least the foamed resin layer described in Item 6 above on a paper-based substrate.
8). The foaming decorative sheet which laminated | stacked the foaming resin layer of the said claim | item 6, and the non-foaming resin layer A in order on the paper quality base material.
9. Item 9. The foamed decorative sheet according to Item 8, further comprising a non-foamed resin layer B between the paper substrate and the foamed resin layer.
10. Item 10. The foamed decorative sheet according to any one of Items 7 to 9, wherein embossing is performed on the outermost surface layer.

Hereinafter, the resin composition for foam production and the foam of the present invention will be described.
1. Resin composition for foam production The resin composition for foam production of the present invention contains a carboxyl group-containing resin, an azodicarbonamide foaming agent (ADCA foaming agent), and a carboxylic acid hydrazide compound.

  In the resin composition for producing a foam of the present invention having the above characteristics, a carboxylic acid hydrazide compound acts as a foaming aid. Conventionally, when a carboxyl group-containing resin and a foaming aid (metal oxide type and fatty acid metal salt type: for example, zinc oxide, zinc stearate, etc.) are used in combination, There was a problem that the original effect was lost or the chromophore was formed and the resin layer and the paper substrate were discolored (yellowing). By using the carboxylic acid hydrazide compound, the effect of the foaming aid was obtained. It is possible to provide a foam which is not impaired and has improved problems such as discoloration.

  Hereinafter, each component of the resin composition for foam production will be described.

Carboxyl group-containing resin The carboxyl group-containing resin is not particularly limited as long as it contains a carboxyl group in the resin. As the carboxyl group-containing resin, for example, a copolymer obtained by a combination of at least one monomer of acrylic acid and methacrylic acid and ethylene can be suitably used. Specifically, it is desirable to use at least one of ethylene-methacrylic acid copolymer (EMAA), ethylene-acrylic acid copolymer (EAA), and ionomers containing these copolymers. As the ionomer, a resin having a structure in which EMAA and / or EAA molecules are intermolecularly bonded with metal ions such as sodium and zinc can be used. By using the above resin (polymer or ionomer), a strong layer resulting from hydrogen bonding or the like in the resin can be formed, so that the surface strength of the foam can be easily increased.

  In the present invention, other resins may be added to the carboxyl group-containing resin. For example, you may add other resin (EVA etc.) in the range which does not impair the effect of this invention. In addition, when mixing and using carboxyl group-containing resin and other resin, it is preferable to set content of carboxyl group-containing resin in 100 weight% of resin components to 60 weight% or more.

Azodicarbonamide foaming agent In the present invention, an azodicarbonamide (ADCA) foaming agent is used as the foaming agent.

  The ADCA-based blowing agent has a high thermal decomposition temperature, and therefore has high film-forming properties, and is preferable from the viewpoint of reducing the risk of in-machine foaming during extrusion film formation. In the present invention, an ADCA foaming agent may be used alone as the thermal decomposition foaming agent, but within a range not impairing the effects of the invention, an oxybisbenzenesulfonylhydrazide (OBSH) foaming agent and the like are used together with the ADCA foaming agent. Other pyrolytic foaming agents may be used in combination.

  The content of the pyrolytic foaming agent in the resin composition can be appropriately set according to the expansion ratio. For example, the expansion ratio is adjusted to 1.5 times or more, preferably about 3 to 7 times. Specifically, 3 to 6 parts by weight is preferable with respect to 100 parts by weight of the resin component, and 3.5 to 5 parts by weight is more preferable. In the present invention, it is only necessary to use only the ADCA foaming agent. However, when the OBSH foaming agent is used in combination, the content of the ADCA foaming agent contained in 100% by weight of the foaming agent is 50% by weight. The above is preferable.

Carboxylic acid hydrazide compound In the present invention, a carboxylic acid hydrazide compound is used as a foaming aid. Even when the carboxylic acid hydrazide compound is used in combination with a carboxyl group-containing resin, the efficacy of the foaming aid is not deactivated by a chemical reaction. Therefore, when producing a foam containing a carboxyl group-containing resin as a resin component, the foam can be obtained without causing discoloration of the foam.

  Examples of the carboxylic acid hydrazide compound include a monohydrazide compound having one hydrazide group in the molecule, a dihydrazide compound having two hydrazide groups in the molecule, and a polyhydrazide compound having three or more hydrazide groups in the molecule. Is mentioned.

Specific examples of the monohydrazide compound include, for example, the general formula (1)
R—CO—NHNH ₂ (1)
[Wherein, R represents a hydrogen atom, an alkyl group or an aryl group which may have a substituent. ]
The monohydrazide compound represented by these is mentioned.

  In the general formula (1), examples of the alkyl group represented by R include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, C1-C12 linear alkyl groups, such as an n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, are mentioned. As an aryl group, a phenyl group, a biphenyl group, a naphthyl group etc. can be mentioned, for example, Among these, a phenyl group is preferable. Examples of the substituent for the aryl group include a halogen atom such as a hydroxyl group, fluorine, chlorine and bromine, a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, a tert-butyl group, and an iso group. -C1-C4 linear or branched alkyl groups, such as a butyl group, etc. can be mentioned.

More specific examples of the hydrazide compound of the general formula (1) include lauric acid hydrazide, salicylic acid hydrazide, form hydrazide, acetohydrazide, propionic acid hydrazide, p-hydroxybenzoic acid hydrazide, naphthoic acid hydrazide, 3-hydroxy- Examples include 2-naphthoic acid hydrazide.

Specific examples of the dihydrazide compound include, for example, the general formula (2)
_{H 2 NHN-X-NHNH 2} (2)
[In formula, X shows group -CO- or group -CO-A-CO-. A represents an alkylene group or an arylene group which may have a substituent. ]
The dihydrazide compound represented by these is mentioned.

  In the general formula (2), examples of the alkylene group represented by A include a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, a heptamethylene group, an octamethylene group, and a nonamethylene group. C1-C12 linear alkylene groups, such as a decamethylene group and an undecamethylene group. Examples of the substituent for the alkylene group include a hydroxyl group. Examples of the arylene group include a phenylene group, a biphenylene group, a naphthylene group, an anthrylene group, and a phenanthrylene group. Among these, a phenylene group and a naphthylene group are preferable. Examples of the substituent of the arylene group include the same substituents as the aryl group.

  Specific examples of the dihydrazide compound of the general formula (2) include oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecandiohydrazide, maleic acid dihydrazide, Examples thereof include dibasic acid dihydrazides such as fumaric acid dihydrazide, diglycolic acid dihydrazide, tartaric acid dihydrazide, malic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, dimer acid dihydrazide, and 2,6-naphthoic acid dihydrazide. Furthermore, various dibasic acid dihydrazide compounds described in Japanese Patent Publication No. 2-4607, 2,4-dihydrazino-6-methylamino-sym-triazine, and the like can also be used as the dihydrazide of the present invention.

  Specific examples of the polyhydrazide compound include polyacrylic hydrazide.

  Among these, dihydrazide compounds are preferable, dibasic acid dihydrazide is particularly preferable, and adipic acid dihydrazide is most preferable.

  The said hydrazide compound can be used individually or in mixture of 2 or more types.

  Although content of a carboxylic acid hydrazide compound is not limited, 0.2-1 weight part is preferable with respect to 1 weight part of ADCA type foaming agents, and 0.3-0.7 weight part is more preferable.

The resin composition for producing other additive foams may contain an additive as long as the effects of the invention are not impaired.

  Examples of the additive include an inorganic filler, a pigment, a lubricant, a fluidity improver, and a crosslinking agent.

Examples of the inorganic filler include calcium carbonate, aluminum hydroxide, magnesium hydroxide, antimony trioxide, and a molybdenum compound. By including the inorganic filler, the amount of the resin component used can be relatively reduced. Moreover, the effect of improving the surface strength can be obtained. Furthermore, when the foam is a foamed resin layer of a foamed decorative sheet, an effect of suppressing curling of the foamed decorative sheet can be obtained by adding an inorganic filler. The content of such an inorganic filler is preferably 0 to 100 parts by weight and more preferably 20 to 70 parts by weight with respect to 100 parts by weight of the resin component.

  Examples of the pigment include titanium oxide, carbon black, black iron oxide, yellow iron oxide, yellow lead, molybdate orange, cadmium yellow, nickel titanium yellow, chromium titanium yellow, iron oxide (valve), cadmium red, ultramarine blue, Inorganic pigments such as bitumen, cobalt blue, chromium oxide, cobalt green, aluminum powder, bronze powder, titanium mica; aniline black, perylene black, azo (azo lake, insoluble azo, condensed azo), polycyclic (isoindole) Linone, isoindoline, quinophthalone, perinone, flavantron, anthrapyrimidine, anthraquinone, quinacridone, perylene, diketopyrrolopyrrole, dibromoanthanthrone, dioxazine, thioindigo, phthalocyanine, indanthrone, halogenated phthalo Cyanine) and organic pigments such as. The content of the pigment is preferably 10 to 50 parts by weight and more preferably 15 to 30 parts by weight with respect to 100 parts by weight of the resin component.

  Any crosslinking agent that promotes crosslinking by electron beam irradiation may be used. Examples thereof include polyfunctional monomers such as neopentyl glycol dimethacrylate and trimethylolpropane trimethacrylate, oligomers, and the like. The crosslinking agent is preferably 0 to 10 parts by weight and more preferably 1 to 4 parts by weight with respect to 100 parts by weight of the resin component.

The resin composition for producing a foam is obtained by preparing and kneading a predetermined amount of the above components. The kneading method is not particularly limited, and may be kneaded with a known mixer or the like.
2. Foam of the Present Invention The foam of the present invention is obtained by heating and foaming a resin composition for producing a foam into a desired shape. For example, the resin composition for producing a foam in a molten state is formed into a desired shape (for example, a sheet shape), and then obtained by heating and foaming the formed body.

  The heating condition is not limited as long as the foam is formed by the decomposition of the pyrolytic foaming agent. The heating temperature is preferably about 190 to 240 ° C., and the heating time is preferably about 15 to 90 seconds.

  Electron beam irradiation may be performed before the heat treatment. Thereby, since a resin component can be bridge | crosslinked, the expansion ratio and surface strength of a foam can be adjusted. The energy of the electron beam is preferably about 150 kV. The irradiation amount is preferably about 10 to 70 kGy. A known electron beam irradiation apparatus can be used as the electron beam source. Crosslinking can also be carried out using a chemical crosslinking agent (crosslinking agent or crosslinking aid).

  The foam of this invention can be utilized suitably as a foaming resin layer of a foaming decorative sheet. For example, the foaming decorative sheet which laminated | stacked the foaming resin layer on the paper-like base material is mentioned. Hereinafter, a foamed decorative sheet will be described as an example of the foam. Specifically, it has a non-foamed resin layer B (arbitrary layer), a foamed resin layer, a non-foamed resin layer A (arbitrary layer), a pattern layer (arbitrary layer), and a surface protective layer (arbitrary layer) on the substrate. The foam decorative sheet will be described.

The base material is not particularly limited as long as it has mechanical strength, heat resistance and the like suitable as a decorative sheet base material. For example, a resin sheet, a fibrous sheet (paper, etc.) can be generally 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 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 10 to 50 μm, more preferably about 10 to 20 μm.

Foamed resin layer The foamed resin layer is formed by foaming a foaming agent-containing resin layer. In this invention, it is obtained by forming the foaming agent containing resin layer shape | molded in the sheet form from the resin composition for foam manufacture, and making it heat-foam.

  Although the thickness of a foamed resin layer is not limited, 70-150 micrometers is preferable in a non-foaming state (before foaming). 300-900 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 foamed resin layer.

The non-foamed resin layer (non-foamed resin layer A) mainly protects the foamed resin layer. In the present invention, a layer formed of a resin composition containing, as a resin component, a polymer obtained using at least one of acrylic acid (CH ₂ ═CHCOOH) and methacrylic acid (CH ₂ ═C (CH ₃ ) COOH) as a monomer. Is preferably a non-foamed resin layer.

  As the resin component, for example, a copolymer obtained by a combination of at least one monomer of acrylic acid and methacrylic acid and ethylene can be suitably used as the resin component. More specifically, it is desirable to use at least one of EMAA, ethylene-acrylic acid copolymer, and ionomer resin. As the ionomer resin, a resin having a structure in which EMAA and / or ethylene-acrylic acid copolymer molecules 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 particularly due to hydrogen bonds in the resin, so that excellent scratch resistance, abrasion resistance, and the like can be obtained. These may be known or commercially available.

  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 is not limited, but is preferably about 10 to 50 μm, more preferably about 10 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 front surface of the non-foamed resin layer A as necessary.

  The design pattern layer imparts design properties to the foamed decorative 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 foaming decorative 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 picture pattern layer, you may form a primer layer previously as needed. 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 a coloring agent, the pigment used for the resin composition for foam manufacture can be used, for example.

  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 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.), stain resistance, and protection of a pattern layer of a foamed decorative sheet, those containing an ionizing radiation curable resin as a resin component 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 decorative 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 foamed decorative sheet>
The manufacturing method of a foaming decorative sheet is not specifically limited. For example, in order to produce a foamed decorative sheet having a foamed resin layer and a non-foamed resin layer A on a substrate such as paper, simultaneous extrusion with a T-die extruder is suitable. A multi-manifold type T-die capable of simultaneously forming two layers by simultaneously extruding molten resin corresponding to two 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 A are placed in separate cylinders, and two types and two layers are simultaneously extruded to form and laminate. do it. In this method, the coextruded laminate is simultaneously laminated (film formation) on the substrate. Since the resin layer laminated simultaneously with extrusion on the base material has adhesiveness by heat melting, it is bonded to the base material.

  In addition, a laminate in which two types and two layers are simultaneously formed in advance may be prepared, placed on the substrate, and bonded to the substrate by thermal lamination.

  In addition, when an inorganic filler is contained in the resin composition forming the foaming agent-containing resin layer, an inorganic filler residue (so-called eyes) is easily generated at the extrusion port (so-called die) of the extrusion molding machine. It tends to be a foreign material on the sheet surface. Therefore, when an inorganic filler is contained in the resin composition forming the foaming agent-containing resin layer, the non-foaming resin layer A and the non-foaming resin layer B are co-extruded with the foaming agent-containing resin layer (three types). (Three layer coextrusion molding) is preferable. The coextrusion molding can be performed, for example, by using a multi-manifold type T die. 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.

  When a surface protective layer containing an ionizing radiation curable resin is formed, the surface protective layer can be cured by electron beam irradiation. Such electron beam irradiation can be performed simultaneously (same processing) as electron beam irradiation performed to crosslink the resin contained in the foaming agent-containing resin layer. 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.

  When producing a foam decorative sheet having a pattern layer, it is preferable to form the pattern layer on the surface of the non-foamed resin layer before the heat treatment.

  In the resin composition for producing a foam of the present invention, a carboxylic acid hydrazide compound acts as a foaming aid. Conventionally, when a carboxyl group-containing resin and a foaming aid (metal oxide type and fatty acid metal salt type: for example, zinc oxide, zinc stearate, etc.) are used in combination, There was a problem that the original effect was lost or the chromophore was formed and the resin layer and the paper substrate were discolored (yellowing). By using the carboxylic acid hydrazide compound, the effect of the foaming aid was improved. A foam with improved problems such as discoloration can be provided without damage.

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

Example 1
A resin composition for foam production (resin composition for forming a foaming agent-containing resin layer) comprising the components shown in Table 1 below was prepared.

  Using a T-die extruder, the foaming agent-containing resin layer (100 μm) was extruded and formed on a substrate (backing paper). As a base material, backing paper “WK-665DO (manufactured by Kojin), thickness 110 μm, basis weight 65 g” was prepared, and a foaming agent-containing resin layer was extruded and formed into a film.

The cylinder temperature which accommodated the resin composition for forming a foaming agent containing resin layer among extrusion conditions was 100 degreeC.

  The laminated body was irradiated with an electron beam (200 kV, 50 kGy) from the foaming agent-containing resin layer side to crosslink EMAA contained in the foaming agent-containing resin layer.

Next, an EVA-based aqueous emulsion was applied (2 g / m ² ) on the foaming agent-containing resin layer to form a primer layer, and a fabric pattern was printed with aqueous ink “Hydric” (manufactured by Dainichi Seika Kogyo). .

  Next, the laminate on which the fabric pattern was printed was heated in a gear oven (at 220 ° C. for 45 seconds) to foam the foaming agent-containing resin layer.

  Finally, the foam was embossed with a texture pattern to produce a foam decorative sheet.

Example 2
A foamed decorative sheet was produced in the same manner as in Example 1 except that the foaming aid was changed to sebacic acid dihydrazide (product name “SDH” manufactured by Otsuka Chemical).

Example 3
A foamed decorative sheet was produced in the same manner as in Example 1 except that the foaming aid was changed to dodecanediohydrazide (product name “DDH” manufactured by Otsuka Chemical).

Example 4
A foamed decorative sheet was prepared in the same manner as in Example 1 except that the foaming aid was changed to isophthalic acid dihydrazide (product name “IDH” manufactured by Otsuka Chemical).

Comparative Example 1
A foamed decorative sheet was prepared by heating at 240 ° C. for 45 seconds in the same manner as in Example 1 except that 5 parts by weight of zinc stearate was used as a foaming aid.

Comparative Example 2
A foamed decorative sheet was produced in the same manner as in Example 1 by heating at 240 ° C. for 45 seconds without adding a foaming aid.

Comparative Example 3
A foamed decorative sheet was produced in the same manner as in Example 1 except that 1 part by weight of urea was used as the foaming aid.

Comparative Example 4
The resin component was EVA (MFR = 20 g / 10 min, vinyl acetate content: 20% by weight) 100 parts by weight, zinc stearate 5 parts by weight as a foaming aid, and foaming agent content 4 parts by weight, A foamed decorative sheet was produced in the same manner as in Example 1.

Test Example 1 (In-machine foaming)
In Examples and Comparative Examples, the presence or absence of in-machine foaming during extrusion was confirmed. In-machine foaming means abnormal foaming before extrusion inside the T-die extruder.

  The case where in-machine foaming was not recognized was marked with ◯, and the case where foaming inside the machine was recognized was marked with x.

Test Example 2 (Whiteness of foamed resin layer)
The whiteness of the foamed resin layer of the foamed wallpaper produced in Examples and Comparative Examples was evaluated using a color difference meter CR-300 (manufactured by Konica Minolta).

  Specifically, the b value was measured, and when the b value was 5 or less, the whiteness was evaluated as high.

Test Example 3 (Scratch resistance)
The scratch resistance of the foamed wallpaper produced in the examples and comparative examples was evaluated.

  The tests and evaluations were conducted in accordance with the “Surface-enhanced wallpaper performance regulations” established by the Japan Vinyl Industry Association Vinyl Construction Committee. Specifically, tests and evaluations were performed according to the following procedures.

  A test piece (foamed wallpaper) was attached to a Gakushin Abrasion Tester (JIS L0849 Abrasion Tester Type II). Using a metal claw designated by the group as a friction machine of the testing machine, a load of 200 g was applied to the tip of the metal claw and the sample was reciprocated five times. The surface condition of the test piece after the test was visually observed.

  Evaluation of scratch resistance in the above-mentioned regulations is as follows: Grade 5: No change, Grade 4: A little change on the surface, Grade 3: The surface appears torn, Grade 2: The surface is torn and a backing material such as paper is visible (long) Less than 1 cm) First grade: There are five stages in which the surface is torn and the backing material such as paper can be seen (length is 1 cm or more).

  The thing corresponding to the said 5th-4th grade was evaluated as (circle), and the thing applicable to the 3rd-1st grade was evaluated as x.

Test Example 4 (Discoloration of paper base material)
The discoloration of the paper-based substrate of the foamed wallpaper produced in the examples and comparative examples was confirmed visually.

  The case where no discoloration was observed was marked with ○, and the case where discoloration was recognized was marked with ×.

  The results of the above test are shown in Table 2 below.

Claims (9)

A laminate before foaming of a foam decorative sheet having at least a foaming agent-containing resin layer on a paper substrate,
The foaming agent-containing resin layer is obtained by extruding a foamed resin composition containing a carboxyl group-containing resin, an azodicarbonamide-based foaming agent, and a carboxylic acid hydrazide compound in a molten state to form a foamed decorative sheet. Laminated body before foaming.   2. The carboxyl group-containing resin is at least one selected from the group consisting of an ethylene-methacrylic acid copolymer, an ethylene-acrylic acid copolymer, and an ionomer containing these copolymers. Laminated body of foamed decorative sheet before foaming.   The laminated body before foaming of the foamed decorative sheet according to claim 1, wherein the carboxyl group-containing resin is an ethylene-methacrylic acid copolymer.   The laminated body before foaming of the foamed decorative sheet according to any one of claims 1 to 3, wherein the carboxylic acid hydrazide compound is adipic acid dihydrazide.   The laminated body before foaming of the foaming decorative sheet in any one of Claims 1-4 in which the said foaming agent containing resin layer is resin-crosslinked by the electron beam.   The foaming decorative sheet obtained by heat-foaming the laminated body before foaming of the foaming decorative sheet of Claim 5. A method for producing a laminate before foaming of a foam decorative sheet,
A process for forming a foaming agent-containing resin layer by extruding a resin composition for foam production containing a carboxyl group-containing resin, an azodicarbonamide-based foaming agent, and a carboxylic acid hydrazide compound on a paper substrate in a molten state. The manufacturing method of the laminated body before foaming of a foaming decorative sheet including this. A method for producing a foam decorative sheet,
(1) A resin composition for producing a foam by extruding a resin composition in a molten state on a paper base material, followed by heating and foaming, wherein the resin contains a carboxyl group and an azodicarbonamide-based foaming agent And a step of forming a foaming agent-containing resin layer by extruding a resin composition for foam production containing a carboxylic acid hydrazide compound in a molten state to form a foaming agent-containing resin layer, and (2) a step of heating and foaming the foaming agent-containing resin layer. A method for producing a foamed decorative sheet.   The foaming according to claim 8, wherein the foaming agent-containing resin layer obtained in the step (1) is irradiated with an electron beam to crosslink the resin contained in the foaming agent-containing resin layer before the step (2). A method for producing a decorative sheet.