JPH0371186B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a decorative sheet, and more particularly, to a method for manufacturing a decorative sheet having an uneven surface that is completely in sync with a printed pattern on a base material. Conventionally, decorative decorative sheets with wood grain or geometric uneven patterns on the surface have been widely used as exterior panels for furniture, fittings, or electrical equipment. It is manufactured by However, with such mechanical methods, it is difficult to create an uneven pattern that closely matches the pattern of the sheet, and there is also the problem that it requires a large number of large equipment, which increases manufacturing costs. be. In order to solve such problems, for example, Japanese Patent Application Laid-open No. 122553/1983 has already proposed printing on a substrate with a printing ink composition containing a so-called curing inhibitor such as an ultraviolet absorber or a polymerization inhibitor. By forming a desired printing pattern on the printed pattern, applying an ultraviolet curable resin composition thereon, and irradiating this with ultraviolet rays, depressions are created in the cured resin layer corresponding to the printed pattern, thus printing A method of manufacturing a decorative sheet has been proposed in which a three-dimensional uneven surface is formed in accordance with a pattern. In such conventional methods, conventionally known ultraviolet absorbers and polymerization inhibitors such as benzotriazole derivatives and quinones are used as curing inhibitors. When a printed pattern is applied to a substrate using a printing ink containing a printing agent, and an uneven surface is formed on the cured resin layer as described above, the biggest problem is that the recesses that are formed corresponding to the printed pattern. It is said that the surface area is still shallow and the three-dimensionality is poor. In addition, in general, in natural precious woods, the conduit part of the tissue has less luster or luster than other parts, but
A conduit portion as a pattern is printed on a base material using the above-described printing ink containing a conventionally known curing inhibitor, and a cured resin layer is formed in accordance with the printed pattern as described above. When a concave portion is formed in the sheet, the concave portion becomes noticeably more glossy or glossy than the other portions, and there is also the problem that it gives a very unnatural impression as a decorative sheet with a wood grain pattern. The present invention has been made in order to solve the above-mentioned problems, and has excellent three-dimensionality because it perfectly synchronizes with the printed pattern on the base material and has deep recesses corresponding to the printed pattern. It is an object of the present invention to provide a method for manufacturing a decorative sheet in which the recesses have substantially no luster or gloss. The method for manufacturing a decorative sheet according to the present invention has the following general formula: (However, R is an alkyl group, an aryl group, an alkylaryl group, or an arylalkyl group, and n is 1 to 6
, M represents an n-valent metal or ammonium. )
A printing pattern is applied to a substrate using a printing ink composition containing an N-nitrosohydroxylamine salt represented by the following formula, an ultraviolet curable resin composition is applied onto this substrate, and then ultraviolet rays are irradiated onto the substrate. The method is characterized in that a concave portion corresponding to the printed pattern is formed in the cured resin layer. In the method of the present invention, the base material is not particularly limited, and examples include paper, resin sheets, wood boards, plywood,
A metal plate or the like is used. As the resin sheet, sheets made of resin such as polyvinyl chloride resin, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, polyvinyl acetate, saturated polyester, polyvinylidene chloride, acrylic resin, thermoplastic polyurethane resin, etc. are preferably used. It will be done.
Such a resin sheet may contain various additives required depending on the resin, such as a plasticizer, a filler, a coloring agent, an antioxidant, and the like. The printing ink used in the method of the present invention contains as a curing inhibitor the general formula (However, R is an alkyl group, an aryl group, an alkylaryl group, or an arylalkyl group, and n is 1 to 6
, M represents an n-valent metal or ammonium. ) Contains an N-nitrosohydroxylamine salt represented by: In the above N-nitrosohydroxylamine salt, R is, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tertiary-butyl, amine, neopentyl, isoamyl, hexyl, isohexyl, heptyl, octyl, isooctyl, 2-ethylhexyl, decyl, isodecyl, lauryl, tridecyl, _C12
~ _C15 mixed alkyl groups, alkyl groups such as stearyl, cyclopentyl, cyclohexyl, cyclooctyl, cyclododecyl, 4-methylcyclohexyl, cycloalkyl groups, aryl groups such as phenyl, naphthyl groups, benzyl, β-phenylethyl, γ-phenyl groups, etc. Aryl alkyl groups such as enylpropyl and β-phenylpropyl, tolyl, xylyl,
Examples include alkylaryl groups such as ethyl phenyl, butylphenyl, tert-butylphenyl, octylphenyl, isooctyl phenyl, tertiary octylphenyl, and nonylphenyl. Examples of M include alkali metals such as sodium and potassium, alkaline earth metals such as calcium and magnesium, metals such as aluminum and cerium, and ammonium. This N-nitrosohydroxylamine salt is added to the printing ink in an amount of 1 to 10% by weight, preferably 3 to 8% by weight.
Contains. Based on the printing ink, the content of this N-nitrosohydroxylamine salt is 1% by weight.
If the amount is less than , when the ultraviolet ray curable resin composition layer coated on the printed pattern of the base material by this printing ink is irradiated with ultraviolet rays, the curing of the resin composition layer corresponding to the printed pattern is suppressed. The effect is poor, and therefore it is difficult to form deep recesses in the cured resin layer in synchronization with the printed pattern. on the other hand,
When the content is more than 10% by weight, diffusion from the printed pattern containing it into the ultraviolet curable resin composition layer above it becomes excessive, and a wide concave portion is formed corresponding to the printed pattern. This is not preferable because it reduces the resolution, so to speak. According to the method of the present invention, since the printing ink contains the above-mentioned N-nitrosohydroxylamine salt as an effect inhibitor, printing with the printing ink is more effective than printing inks containing conventionally known effect inhibitors. It is possible to form significantly deeper recesses in the cured resin layer in accordance with the pattern. The printing ink used in the method of the present invention has a normal composition except for containing the curing inhibitor, and contains, for example, 10 to 15% by weight of a resin and 60 to 85% by weight of an organic solvent, along with an appropriate amount of pigment. do. According to the method of the present invention, after a desired printing pattern is printed on a substrate using such a printing ink, an ultraviolet curable resin composition is applied thereon. The ultraviolet curable resin composition that can be preferably used in the method of the present invention usually contains a film-forming component, a reactive diluent, and a photopolymerization initiator, and if necessary, a solvent, dye and pigment, and filler. It is a resin composition that usually crosslinks and cures within a few seconds when exposed to ultraviolet rays. High molecular weight polymers, oligomers, monomers, etc. having an acryloyl group, a methacryloyl group, or other addition-polymerizable double bonds in the molecule are usually used as the film-forming component. In the present invention, polyester (meth)acrylate, polyurethane (meth)acrylate, epoxy (methacrylate), etc. are preferably used as such coating film-forming components. The reactive diluent is blended to reduce the viscosity of the film-forming component to make it coatable, and to crosslink and network the film-forming component when exposed to ultraviolet rays. , a polyfunctional oligomer or monomer. However, it can also be used by itself as a film-forming component. In the present invention, monomers having two or more acrylate groups and/or methacrylate groups in the molecule are preferably used as such reactive diluents, and specific examples thereof include trimethylolpropane tri(meth)acrylate, Examples include pentaerythritol tri(meth)acrylate, butanediol di(meth)acrylate, neopentyl glycol(meth)acrylate, 1,6-hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, and the like. Furthermore, monofunctional monomers such as 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, N-vinyl-2-pyrrolidone, and tetrahydrofurfuryl (meth)acrylate are used in combination with these. can do. Also,
As the photopolymerization initiator, benzyl, benzophenone, benzoin ether, chlorothioxanthone, diethoxyacetophenone, benzyl dimethyl ketal, etc. are usually used. The amount of each component in the ultraviolet curable resin composition as described above is usually about 20% of the film-forming component.
-90% by weight, preferably 40-70% by weight, reactive diluent about 10-80% by weight, preferably 30-60% by weight, photoinitiator about 0.5-10% by weight, optionally The above-mentioned components are further blended. In the method of the present invention, UV-curable unsaturated polyester resin compositions can also be preferably used. In this resin composition, unsaturated dibasic acids such as maleic acid, fumaric acid, and itaconic acid or their anhydrides are usually used, and if necessary, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, and succinic acid are used. , adipic acid, sebacic acid, etc., and ethylene glycol, propylene glycol, butylene glycol, glycerin, diethylene glycol, triethylene glycol, neopentyl glycol, pentaerythritol, trimethylolpropane, etc. A reaction product with a polyhydric alcohol is used as a film-forming component. A photosensitizer and, if necessary, higher fatty acids such as tung oil, linseed oil, dehydrated castor oil, and soybean oil, polymerizable monomers, other fillers, pigments, etc. are blended into this to form an ultraviolet curable resin composition. is formed. It is also possible to use urethane-modified polyester resins in which unsaturated polyester is partially substituted with tolylene diisocyanate, methylene diisocyanate, etc., or epoxy-modified resins. Next, according to the present invention, this ultraviolet curable resin composition layer on the base material is irradiated with ultraviolet rays to form deep recesses in the cured resin layer corresponding to the printed pattern. The ultraviolet rays may be irradiated by any conventional method known in the art, for example, by using an ultraviolet source such as a xenon lamp, a low pressure, medium pressure, high pressure, or ultra-high pressure mercury lamp. The amount of ultraviolet rays that is sufficient to fully cure the ultraviolet curable resin composition may be irradiated, and is appropriately selected depending on the composition. For example, the main wavelength is 365 mμ, and the output is 80 W/cm.
In the case of a mercury lamp, irradiation may be performed for one to several seconds. FIG. 1 shows a sectional view of a main part of a base material 1 before irradiation with ultraviolet rays in the method of the present invention, and a desired printed pattern 2 is formed on this base material with a printing ink containing the curing inhibitor. Further, a resin layer 3 made of the above-mentioned ultraviolet curable resin composition is formed thereon. In such a resin layer, the mechanism is not necessarily clear, and the present invention is not limited by any theory, but as shown in the figure, the curing inhibitor 4 of the printed pattern 2 is The resin layer 3 is diffused along the surface side,
It will be included in the resin layer along the printed pattern.
As a result, by irradiating such a resin layer with ultraviolet rays, as shown in FIG. 2, crosslinking is delayed in the portion 5 of the resin layer along the printed pattern;
The other portions 6 are quickly crosslinked. That is, the resin layer that does not correspond to the printed pattern is rapidly cured by ultraviolet irradiation and becomes three-dimensional, but the portion 5 of the resin layer in which the curing inhibitor has been diffused is delayed in curing, forming the recess 7. In this way, a cured resin layer 8 having an uneven surface completely in sync with the printed pattern is formed. Furthermore,
The recesses thus formed are less glossy or glossy than other parts. As described above, according to the method of the present invention, a printing pattern is applied to a substrate using a printing ink containing the above-mentioned curing inhibitor N-nitrosohydroxylamine salt, and an ultraviolet curable resin composition is applied on the substrate. is applied and then irradiated with ultraviolet rays, so the curing of the resin layer corresponding to the printed pattern is significantly delayed.
As a result, deeper recesses than ever before are formed in the resin layer corresponding to the printed pattern, and thus the formed uneven pattern perfectly matches the printed pattern and has excellent three-dimensionality. Furthermore, this recessed portion has substantially no luster or luster, and for example, when a conduit portion in a wood grain pattern is formed into a recessed portion, it has a natural three-dimensionality comparable to that of natural precious wood. Furthermore, since the printed pattern is covered with a cross-linked and cured resin layer, it has excellent heat resistance, abrasion resistance, strength, and desirable properties as a decorative sheet. The method for producing a decorative sheet according to the present invention will be described below with reference to Examples. Example 1 A vinyl chloride resin sheet with a thickness of 0.1 mm containing 20 parts by weight of plasticizer per 100 parts by weight of resin was used as the base material, solid printing was performed on this with ordinary gravure ink, and then a wood grain pattern was applied. After printing, a pattern representing the conduit portion was printed using a printing ink containing the hardening inhibitor shown in the table. A UV-curable resin composition containing trimethylolpropane trimethacrylate as a film-forming component is applied onto this printed pattern to a certain thickness.
It was applied to a thickness of 20 μm. Next, print onto this resin layer.
The resin layer was cured by irradiating ultraviolet rays for 1 second using an 80 W/cm mercury lamp to form an uneven surface. Further, as a comparative example, a resin layer was cured in the same manner as above except that a conventional printing ink containing a polymerization inhibitor was used. The depth of the recesses, that is, the degree of recess on each of the uneven surfaces formed as described above was measured using a contraster, and the luster or luster of the recesses was visually observed. The results are shown in the table. In addition, in the gloss evaluation in the table, ○ means that the concave part is less glossy than other parts, △ means that it is slightly glossy, ×
indicates that each part is more glossy than other parts. As is clear from the table, according to the method of the present invention, deep recesses are formed corresponding to the printed pattern, and

【table】

【table】 This recessed portion does not have luster or luster.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of essential parts showing the base material, the printed pattern thereon, and the ultraviolet curable resin composition layer, and Figure 2 shows the unevenness of the cured resin layer corresponding to the printed pattern by the method of the present invention. FIG. 2 is a sectional view of a main part showing a decorative sheet on which a pattern is formed. DESCRIPTION OF SYMBOLS 1... Base material, 2... Print pattern, 3... Ultraviolet curable resin composition layer, 4... Curing inhibitor, 7... Recessed part, 8... Cured resin layer.

Claims (1)

[Claims] 1. General formula (However, R is an alkyl group, an aryl group, an alkylaryl group, or an arylalkyl group, and n is 1 to 6
, M represents an n-valent metal or ammonium. ) A printing pattern is applied to a substrate using a printing ink composition containing an N-nitrosohydroxylamine salt represented by the following formula, an ultraviolet curable resin composition is applied onto this substrate, and then ultraviolet rays are irradiated onto the substrate. A method for producing a decorative sheet, comprising: forming concave portions in the cured resin layer that match the printed pattern. 2. The method for producing a decorative sheet according to claim 1, wherein the N-nitrosohydroxyamine salt is an N-nitrosophenylhydroxylamine aluminum salt.