JP4811535B2 - Foamed wallpaper with excellent surface properties - Google Patents

Description

  The present invention relates to a foam wallpaper having excellent surface characteristics (surface strength, stain resistance, weather resistance, etc.).

  Conventionally, in the field of foamed wallpaper, attempts have been made to improve the surface characteristics of wallpaper by using ionizing radiation curable resins.

  For example, Patent Document 1 is characterized in that a foamed embossed decorative sheet having a foamable resin layer on a base material and optionally provided with a printing layer is provided with an ultraviolet curable resin layer on the surface. A foamed embossed decorative sheet is disclosed.

  However, in this technique, since an ultraviolet curable resin is used for the surface protective layer, among the surface characteristics, the stain resistance is particularly insufficient, and there is room for further improvement. In addition, since the UV curable resin almost contains a UV initiator, the weather resistance of the decorative sheet tends to be insufficient.

  Further, in Patent Document 1, as a method for producing the decorative sheet, a foamable resin is applied and dried on a base material, a printing layer is optionally provided by printing, and an ultraviolet curable resin is applied and dried thereon. A process of foaming a foamable resin by heating, embossing the surface, and then irradiating the surface with ultraviolet rays to completely cure the ultraviolet curable resin is disclosed.

  However, this manufacturing method has a problem that the sheet is clung to the transfer roll in the foaming step, the embossing step, and the like, and the smooth production of the decorative sheet is hindered.

  As a wallpaper using an ionizing radiation curable resin, for example, Patent Document 2 also discloses. Specifically, Patent Document 2 discloses a foamed wallpaper in which a foamed resin layer cured with active energy rays and a printed layer are sequentially laminated on a base sheet.

  This technique is intended to improve the surface characteristics of foamed wallpaper by providing a foamed resin layer cured with resin by irradiation with active energy rays.

  However, the foamed wallpaper produced by this technique also has insufficient surface characteristics, and further improvements are required.

  In Cited Document 2, an active energy ray-curable foamable resin layer is laminated on a base material sheet, a printed layer is laminated on the foamable resin layer, and a foaming sheet is produced. A method for producing a foamed wallpaper is disclosed in which a foamable resin layer is formed by foaming a foamable resin layer of a sheet, and then the foamed resin layer is cured by irradiation with active energy rays.

  Similar to the manufacturing method described in Patent Document 1, this manufacturing method has also been pointed out that, in the printing layer formation, foaming, embossing process, etc., the sheet clings to the transfer roll and hinders the smooth manufacturing of the foam wallpaper. .

JP-A-9-109303 Japanese Patent Laid-Open No. 10-296894

  The main object of the present invention is to provide a foam wallpaper having excellent surface strength, stain resistance and weather resistance.

  As a result of intensive studies to achieve the above object, the present inventor has found that a foamed wallpaper formed with a specific layer can achieve the above object, and has completed the present invention.

That is, the present invention relates to the following foam wallpaper.
1. A foamed wallpaper obtained by sequentially forming a foamed resin layer and a surface protective layer on a paper base material,
(1) The foamed resin layer has at least one selected from the group consisting of an ethylene homopolymer resin and an ethylene copolymer resin as a resin component and is crosslinked by electron beam irradiation,
(2) The surface protective layer contains an electron beam curable resin and silica,
(3) The electron beam curable resin contains a urethane acrylate prepolymer and an acrylate monomer, and is crosslinked by electron beam irradiation.
Foam wallpaper characterized by that.
2. Item 2. The foamed wallpaper according to Item 1, which has an embossed pattern.

  Hereinafter, the foamed wallpaper of the present invention and the manufacturing method thereof will be described in detail.

  The foamed wallpaper of the present invention is characterized in that an electron beam curable foamed resin layer and an electron beam curable surface protective layer are sequentially formed on a paper-based substrate.

The paper-based substrate is not particularly limited, and those conventionally known as backing paper for wallpaper can be widely used. For example, flame retardant paper (sheets made by treating pulp-based sheets with flame retardants such as guanidine sulfamate and guanidine phosphate); inorganic paper mixed with inorganic agents such as aluminum hydroxide and magnesium hydroxide; fine paper, thin paper And general paper such as Japanese paper.

The basis weight of the paper-based substrate is not particularly limited, but is usually about 20 to 300 g / m ² , preferably about 40 to 110 g / m ² .

Electron beam curable (crosslinked) foamed resin layer An electron beam curable foamed resin layer (hereinafter abbreviated as “foamed resin layer”) is formed on a paper-based substrate.

  In the foamed resin layer, the resin constituting the layer is crosslinked by electron beam irradiation.

  Although it does not specifically limit as resin which comprises a foamed resin layer, Considering processability, foamability, etc., ethylene-type resin is preferable. For example, ethylene homopolymer resin, ethylene-vinyl acetate copolymer resin (EVA), ethylene-methyl acrylate copolymer resin (EMA), ethylene-ethyl acrylate copolymer resin (EEA), 3 to 5 carbon atoms Examples thereof include olefin copolymer resins such as ethylene-alkyl acrylate copolymer resins and ethylene-methyl methacrylate copolymer resins (EMMA), and mixtures of these resins. Any of these resins can be easily crosslinked by electron beam irradiation. Among these, EVA is particularly preferable.

  EVA preferably has a vinyl acetate content of 10 to 30% by weight and a melt flow rate at 190 ° C. of 40 to 120 g / 10 min.

  The foaming agent contained in the foamed resin layer is preferably a pyrolytic foaming agent. Examples thereof include azo compounds such as azodicarbonamide and azobisformamide, and hydrazine compounds such as 4,4′-oxybisbenzenesulfonyl hydrazide. These foaming agents can be used alone or in combination of two or more.

  The addition amount of the foaming agent may be appropriately determined in consideration of the degree of foaming, the design of the foamed wallpaper, etc., but is usually about 2 to 15 parts by weight, preferably about 3 to 6 parts by weight with respect to 100 parts by weight of the resin. .

  The foamed resin layer may contain an inorganic filler as necessary. Examples of the inorganic filler include calcium carbonate, aluminum hydroxide, magnesium hydroxide, antimony trioxide, zinc borate, and a molybdenum compound. Among these, aluminum hydroxide and calcium carbonate are particularly preferable. By containing an inorganic filler, the effect of suppressing the see-through of the foamed wallpaper, the effect of enhancing the surface characteristics of the foamed wallpaper, and the like can be obtained. As addition amount of an inorganic filler, it is 0-100 weight part with respect to 100 weight part of resin, and 20-70 weight part is preferable.

  The foamed resin layer may contain a crosslinking aid that promotes resin crosslinking by electron beam irradiation, if necessary.

  The crosslinking aid is not particularly limited as long as it promotes resin crosslinking by electron beam irradiation, and examples thereof include polyfunctional monomers such as neopentyl glycol dimethacrylate and trimethylolpropane trimethacrylate, oligomers, and the like. As addition amount of a crosslinking adjuvant, it is 0-10 weight part with respect to 100 weight part of resin, and 1-4 weight part is preferable.

  The foamed resin layer may be colored by adding a pigment or the like, if necessary. Moreover, you may add well-known adjuvants, such as a foaming cell regulator, a heat stabilizer, a flame retardant. There are no particular limitations on the type, amount, and the like of these auxiliaries, which can be set as appropriate according to the desired characteristics of the foam wallpaper.

  The foamed resin layer is formed by, for example, forming a layer made of a composition for forming a foamed resin layer (a mixture containing a resin, a foaming agent, various auxiliary agents, and the like) on a paper substrate, and then crosslinking the layer by electron beam irradiation. Furthermore, it can form by making a foaming agent foam.

  For example, a dry lamination method or an extrusion lamination method can be applied to the formation of the foamed resin layer. Alternatively, the foamed resin layer forming composition may be formed into a sheet (film) by a T-die extrusion method, a calendering method, or the like, and at the same time, the foamed resin layer forming composition may be laminated on a paper base. When the foamed resin layer forming composition exhibits high fluidity at the processing temperature, for example, a coating technique such as a roll coating method, a gravure coating method, or a comma coating method may be employed. In the present invention, among the above T-die extrusion methods, the foamed resin layer is formed by using a T-die extruder or a multi-manifold type T-die extruder equipped with a feed block capable of simultaneous multilayer extrusion. A forming composition and a surface protective layer forming composition for forming an electron beam curable surface protective layer (hereinafter abbreviated as “surface protective layer”), which will be described later, are integrally formed on a paper-based substrate by a multilayer coextrusion method. May be. This method is particularly suitable when the temperature characteristics of the compositions forming both layers are equivalent. When the multilayer coextrusion method is used, electron beam irradiation and heat foaming may be performed after the two resin layers are simultaneously formed.

  What is necessary is just to irradiate an electron beam in order to bridge | crosslink resin which comprises a foamed resin layer. As the electron beam irradiation device, for example, various electron beam accelerators such as a cockcroft Walton type, a bandegraft type, a resonant transformer type, an insulated core transformer type, a linear type, a dynamitron type, and a high frequency type can be used.

  The energy of the electron beam is usually 50 to 300 kV, preferably about 80 to 200 kV. The irradiation amount is usually about 1 to 30 Mrad, preferably about 2 to 10 Mrad.

  The foaming agent can be foamed by heating, for example. The heating conditions are not particularly limited, and can be appropriately set according to the desired degree of foaming, the design of the foamed wallpaper, and the like. Usually, it may be heated at 200 to 240 ° C. for 20 to 40 seconds.

  Although the thickness of a foamed resin layer (after foaming) is not specifically limited, Usually, it is 300-1000 micrometers, Preferably it is about 400-800 micrometers.

A surface protective layer is formed on the electron beam curable surface protective layer foamed resin layer (a pattern layer to be described later may be formed on the surface). The surface protective layer is an electron beam curable type, and the constituent resin is cross-linked by electron beam irradiation. By forming such a surface protective layer, the surface characteristics of the foamed wallpaper are enhanced.

  Although it does not specifically limit as resin which comprises a surface protective layer, It has as a main component the prepolymer (including an oligomer) and / or monomer which contain the radically polymerizable double bond which can carry out a polymerization crosslinking reaction by electron beam irradiation in a molecule | numerator. A transparent resin can be used. These prepolymers or monomers can be used alone or in combination. The curing reaction is usually a cross-linking curing reaction.

  Specifically, as the prepolymer or monomer, a compound having in the molecule a radically polymerizable unsaturated group such as a (meth) acryloyl group or (meth) acryloyloxy group, or a cationically polymerizable functional group such as an epoxy group. Is mentioned. Further, a polyene / thiol prepolymer based on a combination of polyene and polythiol is also preferable. Here, the (meth) acryloyl group means an acryloyl group or a methacryloyl group.

  Examples of the prepolymer having a radically polymerizable unsaturated group include polyester (meth) acrylate, urethane (meth) acrylate, epoxy (meth) acrylate, melamine (meth) acrylate, triazine (meth) acrylate, and silicone (meth) acrylate. Etc. These molecular weights are usually preferably about 250 to 100,000.

  As a monomer which has a radically polymerizable unsaturated group, methyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, phenoxyethyl (meth) acrylate etc. are mentioned as a monofunctional monomer, for example. Examples of the polyfunctional monomer include diethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane ethylene oxide tri (meth) acrylate, dipentaerythritol tetra ( And (meth) acrylate, dipentaerythritol penta (meth) acrylate, and dipentaerythritol hexa (meth) acrylate.

  Examples of the prepolymer having a cationic polymerizable functional group include prepolymers of epoxy resins such as bisphenol type epoxy resins and novolac type epoxy compounds, and vinyl ether type resins such as fatty acid type vinyl ethers and aromatic vinyl ethers. Examples of the thiol include polythiols such as trimethylolpropane trithioglycolate and pentaerythritol tetrathioglycolate. Examples of the polyene include those in which allyl alcohol is added to both ends of polyurethane by diol and diisocyanate.

  The surface protective layer may contain silica as necessary. By including silica, the effect of improving scratch resistance and blocking resistance can be obtained. The content of silica is not particularly limited, but is usually about 1 to 50 parts by weight, preferably about 5 to 20 parts by weight with respect to 100 parts by weight of the resin.

  The surface protective layer may contain a known auxiliary agent such as a crosslinking auxiliary agent, a heat stabilizer, a flame retardant, etc., if necessary. There are no particular limitations on the type, amount, and the like of these auxiliaries, which can be set as appropriate according to the desired characteristics of the foam wallpaper.

  For the formation of the surface protective layer, a dry lamination method, an extrusion lamination method, or the like can be applied as in the method of forming the foamed resin layer.

  Electron beam irradiation equipment, irradiation conditions, etc. are the same as in the case of the foamed resin layer described above. Usually, after forming the foamed resin layer and the surface protective layer, both layers may be irradiated with an electron beam at once from the surface protective layer side. The foaming of the foamed resin layer is preferably carried out after forming both layers and then crosslinking the resins in both layers by electron beam irradiation.

  The thickness of the surface protective layer is not particularly limited and can be appropriately set according to the characteristics of the final product, but is usually about 0.1 to 50 μm, preferably about 1 to 20 μm.

A picture pattern layer may be further formed between the picture print layer foamed resin layer and the surface protective layer.

  The design pattern layer imparts design properties with a desired design to the foamed wallpaper, and the type of the design is not particularly limited. Examples thereof 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 method for forming the pattern layer is not particularly limited. For example, a colored ink or coating obtained by dissolving (or dispersing) a known colorant (dye or pigment) in a solvent (or dispersion medium) together with a binder resin. What is necessary is just to form in the foaming resin layer surface by the printing method etc. which used the agent etc. Therefore, when a pattern layer is formed on the surface of the foamed resin layer, the foamed resin layer and the surface protective layer cannot be formed by multi-layer coextrusion, so that the pattern layer is formed after the pattern layer is formed. A surface protective layer may be further formed.

  Examples of the colorant include inorganic pigments such as carbon black, titanium white, zinc white, dial, bitumen, and cadmium red; azo pigments, lake pigments, anthraquinone pigments, quinacridone pigments, phthalocyanine pigments, isoindolinone pigments, dioxazine pigments. Organic pigments such as aluminum powder, metal powder pigments such as bronze powder, pearlescent pigments such as titanium oxide-coated mica and bismuth oxide chloride; fluorescent pigments; These colorants can be used alone or in admixture of two or more. These colorants may further contain fillers such as silica, extender pigments such as organic beads, neutralizing agents, surfactants and the like.

  Examples of the binder resin include acrylic resins, styrene resins, polyester resins, urethane resins, chlorinated polyolefin resins, vinyl chloride-vinyl acetate copolymer resins, polyvinyl butyral resins, alkyd resins, petroleum Resin, ketone resin, epoxy resin, melamine resin, fluorine resin, silicone resin, fiber derivative, rubber resin and the like. These resins can be used alone or in admixture of two or more.

  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 Inorganic solvents and the like, such as water; chlorinated organic solvents. These solvents (or dispersion media) can be used alone or in admixture of two or more.

  Examples of the printing method used for forming the pattern layer include a gravure printing method, an offset printing method, a screen printing method, a flexographic printing method, an electrostatic printing method, and an inkjet printing method. When forming a solid pattern pattern layer, for example, roll coating method, knife coating method, air knife coating method, die coating method, lip coating method, comma coating method, kiss coating method, flow coating method, dip coating Various coating methods such as a coating method may be mentioned. In addition, the hand-drawn method, the ink-sink method, the photographic method, the transfer method, the laser beam drawing method, the electron beam drawing method, the metal partial evaporation method, the etching method, etc. may be used or combined with other forming methods. Good.

  The thickness of the pattern layer is not particularly limited and can be set as appropriate according to product characteristics. The layer thickness at the time of coating is about 1 to 15 μm, and the layer thickness after drying is about 0.1 to 10 μm.

Embossing The foamed wallpaper of the present invention may optionally be provided with an embossed pattern in addition to the embossed pattern generated by foaming. That is, you may have arbitrary uneven | corrugated patterns from a surface protective layer to a foamed resin layer.

  Usually, the concavo-convex pattern is applied by embossing. The embossing method is not particularly limited, and for example, a preferable method is to heat soften the front surface of the surface protective layer, pressurize and shape with an emboss plate, and then cool. For embossing, a known single-wafer or rotary embossing machine is used. Examples of the concavo-convex shape include a wood grain plate conduit groove, a stone plate surface unevenness (such as granite cleaved surface), a cloth surface texture, a satin texture, a grain, a hairline, a ridge line, and the like.

Production method of foamed wallpaper The production method of the foamed wallpaper of the present invention is not particularly limited, and for example, a production method having the following steps in order can be mentioned as a suitable production method.
(1) Step 1 of forming a layer made of a composition for forming an electron beam curable foamed resin layer on a paper substrate,
(2) Step 2 of forming a layer comprising the electron beam curable surface protective layer forming composition on the layer obtained in Step 1;
(3) Step 3 of crosslinking the electron beam curable resin contained in the two layers by irradiating an electron beam, and (4) Step 4 of foaming the pyrolytic foaming agent by heating.

  Hereinafter, this manufacturing method will be described.

  In step 1, a layer made of the foamed resin layer forming composition is formed on the paper substrate.

  In step 2, a layer made of the surface protective layer forming composition is formed on the layer obtained in step 1.

  In steps 1 and 2, as described above, a dry lamination method, an extrusion lamination method, or the like can be applied as a method for forming each layer.

  A pattern layer may be formed on the surface of the foamed resin layer as necessary. When the pattern layer is formed, it is formed between step 1 and step 2. The method for forming the pattern layer is as described above.

  In step 3, the electron beam curable resin contained in the two layers is crosslinked by irradiating an electron beam.

  The electron beam irradiation conditions and the like are as described above. In this production method, resin crosslinking by electron beam irradiation is performed prior to heating and foaming of the foaming agent. Therefore, the resin layer is cured by the action of resin crosslinking, and in the subsequent foaming agent foaming step, the laminated sheet is transferred to the transfer roll. The clinging is suppressed. Thereby, the smooth transfer of a lamination sheet is realizable, and the subsequent foaming agent can be foamed smoothly.

  In step 4, the pyrolytic foaming agent is foamed by heating. About heating conditions etc., as above-mentioned, it can adjust suitably according to the designability of foaming wallpaper, and the foaming degree.

  The foamed wallpaper of the present invention is formed by sequentially forming an electron beam curable foamed resin layer and an electron beam curable surface protective layer on a paper-based substrate, and has excellent surface strength, stain resistance and weather resistance.

  According to the production method of the present invention, the resin layer is cured by electron beam irradiation prior to the heat foaming of the foaming agent, so that the resin layer is cured by the action of the resin crosslinking, and in the subsequent foaming agent foaming step, the laminated sheet Is prevented from clinging to the transfer roll. Thereby, a smooth transfer of a lamination sheet is realizable, a subsequent process can be implemented smoothly and a foam wallpaper can be manufactured.

  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
Ethylene-vinyl acetate copolymer resin (MFR at 190 ° C .: 70 g / 10 min, vinyl acetate content: 20% by weight), inorganic filler (calcium carbonate), colorant (titanium oxide), foaming agent and stabilizer The mixture was used as a foamed resin layer forming composition. The composition of the foamed resin layer forming composition is shown in Table 1 below.

  The composition was sheeted on a backing paper having a thickness of 110 μm (basis weight: 70 g) to a thickness of 100 μm using a T-die molding machine.

  Next, after a pattern layer was formed on the surface of the foamed resin layer with an acrylic water-based ink, an electron beam curable resin layer (surface protective layer) having a thickness of 10 μm was formed on the surface. The composition of the electron beam curable resin layer forming composition is shown in Table 2 below.

  An electron beam of 175 kV was irradiated from the electron beam curable resin layer side by 3 Mrad to crosslink the electron beam curable resin contained in the foamed resin layer and the surface protective layer.

  Next, a foamed embossed pattern was imparted by heating in a 230 ° C. oven for 30 seconds to produce a foamed wallpaper.

Comparative Example 1
Example 1 except that an ultraviolet (UV) curable resin layer was formed instead of the electron beam curable resin layer (surface protective layer) and UV irradiation for resin crosslinking was performed after the foamed embossed pattern was applied. A foamed wallpaper was prepared in the same manner. The composition of the electron beam curable resin layer forming composition is shown in Table 3 below.

Comparative Example 2
A foamed wallpaper was prepared in the same manner as in Comparative Example 1 except that UV irradiation was performed before the foamed embossed pattern was applied.

Comparative Example 3
A foamed wallpaper was prepared in the same manner as in Example 1 except that the electron beam curable resin layer was not formed.

Test example 1
The characteristics (surface roughness, surface strength, contamination resistance and weather resistance during the production process) of the foamed wallpaper produced in the examples and comparative examples were evaluated.
(Surface stickiness during the manufacturing process)
The presence or absence of clinging to the roll was visually observed by passing the sheet through a portion (laminate portion) where the metal roll and the rubber roll were in contact and rotating simultaneously. The higher the degree of stickiness, the easier it is for rolls to be taken (attachment to the rolls) in the manufacturing process.
(Surface strength)
The surface strength of the foamed wallpaper was evaluated by the method of “Surface-Enhanced Product Performance Labeling Regulations” established by the Japan Vinyl Industry Association Building Committee.
(Contamination resistance)
Contamination resistance was evaluated by the method of “Prevention of Anti-Smudge Product Performance Labeling” established by the Japan Vinyl Industry Association Construction Department.

  These evaluation results are shown in Table 4 below.

○: Good △: Somewhat bad ×: Bad

Claims (2)

A foamed wallpaper obtained by sequentially forming a foamed resin layer and a surface protective layer on a paper base material,
(1) The foamed resin layer has at least one selected from the group consisting of an ethylene homopolymer resin and an ethylene copolymer resin as a resin component and is crosslinked by electron beam irradiation,
(2) The surface protective layer contains an electron beam curable resin and silica,
(3) The electron beam curable resin contains a urethane acrylate prepolymer and an acrylate monomer, and is crosslinked by electron beam irradiation.
Foam wallpaper characterized by that. The foam wallpaper of Claim 1 which has an embossed pattern .