JP3237498B2 - Surface-enhanced decorative paper and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing decorative paper used for decorative boards used for furniture, housing equipment and the like.
Particularly, the present invention relates to a decorative paper used for a high-grade decorative board having high surface hardness and excellent durability.

[0002]

2. Description of the Related Art Conventional decorative paper used for horizontal surfaces of furniture and household equipment is printed on a base paper having good permeability such as titanium paper and then coated with a thermosetting resin such as melamine resin and diallyl phthalate resin. A resin-impregnated paper made by impregnation is put on a base material such as phenol core paper or particle board, and is heated and compressed through a mirror plate to produce. According to this method, a decorative plate having surface hardness and abrasion resistance required for a horizontal surface can be obtained, but on the other hand, it has to be expensive because of poor production efficiency.

On the other hand, the use of water-based inks in decorative paper has recently been emphasized because problems such as the use of solvents and the effect on the environment of conventional oil-based inks have been emphasized in recent years.
The ink used is becoming mainstream. Further, in order to improve the production cost, various methods of using an electron beam-curable resin formulated as a solvent-free resin instead of a thermosetting resin have been studied in various ways. Things have not been obtained. In other words, when a solvent-free electron beam-curable resin is applied from the surface of the aqueous ink and electron beam irradiation is performed in a short time in the same process, the polarity of the aqueous ink is high, so that the penetration of the resin is hindered and the paper Not penetrate enough,
Before the impregnation, the electron beam curable resin is cured. Therefore, there is a problem that the adhesive force between the electron beam-curable resin layer and the aqueous ink layer is small, and furthermore, the curing shrinkage of the electron beam-curable resin layer is added, and the electron beam-curable resin is easily separated from the surface of the ink layer. Further, since the electron beam-curable resin hardly penetrates, the reinforcement of the paper layer becomes insufficient.

[0004] In general, active energy ray-curable solventless paints and inks which utilize the energy of active energy rays such as electron beams and ultraviolet rays for curing resins as described above have a greater effect than thermosetting. The advantages such as energy saving, high productivity and low temperature curing are emphasized. However, the active energy ray-curable non-solvent type resin composition used here generally comprises an oligomer (or a prepolymer) and a monomer as main components, and in photocuring, further comprises a photopolymerization initiator and a sensitizer. Although a 100% liquid type or organic solvent solution type resin composition is applied, the odor caused by the use of a low molecular weight vinyl monomer or a solvent for viscosity adjustment added to facilitate the coating workability is applied. There are many safety and health problems such as deterioration of the working environment due to fire, danger of fire due to ignition of monomers and solvents, and toxicity. Also, 100
%, There is a disadvantage that the addition of the monomer originally impairs the physical properties of the target oligomer. Therefore, no monomer or solvent is required,
It is desired to develop a water-based ultraviolet or electron beam curable resin composition that does not have the above-mentioned problems.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has as its object the hardness and hardness which can be used on a horizontal surface such as furniture and housing equipment. It is an object of the present invention to provide a high-quality decorative paper having abrasion resistance and capable of being manufactured efficiently and at low cost, and a method for manufacturing the same.

[0006]

SUMMARY OF THE INVENTION The present invention has been conceived in order to solve this problem, and the invention of claim 1 is to provide an active energy ray-curable aqueous solution obtained by providing a print layer on paper and curing the print layer thereon. This is a surface-reinforced decorative paper provided with a surface protective layer made of a resin layer. The invention according to claim 2 is characterized in that the active energy ray-curable aqueous resin is an ultraviolet or electron beam-curable polymer,
A resin composition comprising an oligomer, a monomer, and the like, wherein at least one component contains a bifunctional or more functional urethane acrylate or urethane methacrylate represented by the following formula (Chemical Formula 1). 2. The surface-reinforced decorative paper according to 1.

[0007]

Embedded image

[0008] The invention of claim 3 is an ether-based polyol in which the dihydric alcohol residue constituting the bifunctional or higher functional urethane acrylate or urethane methacrylate represented by the above formula (Formula 1) has a structure of ethylene oxide and propylene oxide. The surface-reinforced decorative paper according to claim 2, which is obtained by a compound selected from the group consisting of: The invention according to claim 4 is that the composition ratio (molar ratio) of each repeating unit structure of ethylene oxide and propylene oxide constituting the dihydric alcohol residue of the formula (Formula 1) is 9: 1 to 1: 1.
The surface-reinforced decorative paper according to claim 2 or 3, wherein the ratio is in the range of 4: 6. According to the invention of claim 5, a paper is printed or colored with an aqueous ink, and a coating agent containing an active energy ray-curable aqueous resin as a main component is applied as a surface protective layer on the dried ink layer. A method for producing a surface-reinforced decorative paper, which is characterized by irradiating an active energy ray (ultraviolet ray, electron beam, etc.) after heat drying.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
First, the constituent materials of the surface-reinforced decorative paper will be described, and then the method for producing the active energy ray-curable aqueous resin composition used as the surface protective layer of the decorative paper will be described in detail.

The decorative base paper of the decorative paper according to the present invention includes:
Base paper for decorative paper having a basis weight of 30 to 120 g / m2 is suitable.
A sealer treatment or the like may be performed in advance with a urethane-based resin or a vinyl-based resin. This is printed with an aqueous ink or colored over the entire surface. The printing method may be a known method such as a gravure printing method. The coating method of the surface protective layer is optional, but in the production stage, a roll coater, a reverse roll coater, a gravure coater, a knife coater or the like is generally used.

Next, a method for producing the active energy ray-curable aqueous resin composition will be described. Examples of the diisocyanate compound constituting the bifunctional or higher functional urethane acrylate or urethane methacrylate represented by the formula (Formula 1) include tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), diphenylmethane diisocyanate (MDI), and naphthylene diisocyanate ( Aromatic diisocyanates such as NDI),
Lysine diisocyanate methyl ester (LDIM),
Trimethylhexamethylene diisocyanate (TMD
I), dimer acid diisocyanate (DDI), hexamethylene diisocyanate, methylcyclohexylene-
2,4 (2,6) -diisocyanate, 1,3 (4)-
Aliphatic diisocyanates such as (diisocyanatomethol) cyclohexane, 4,4-bis (isocyanatocyclohexyl) methane, and isophorone diisocyanate can be used. As the diol component, ethylene glycol, propylene glycol, diethylene glycol,
Low molecular weight polyols such as dipropylene glycol, oligomer polyols such as polyoxyethylene glycol and polyoxypropylene glycol, and, if necessary, random or block polyethers of ethylene oxide and propylene oxide can also be used.

In order to introduce acrylate or methacrylate at both ends of the polyurethane diol obtained from the above-mentioned diisocyanate and diol, it is necessary to use a compound having a methacryloyl group and an isocyanate group in one molecule.
Functional monomers such as m-isopropenyl-α, α-dimethylbenzyl isocyanate (m-TMI) and 2-methacryloyloxyethyl isocyanate (MOI) can be used. Further, in addition to the various diisocyanate compounds exemplified above, an active hydrogen group such as an acryloyl or methacryloyl group and a hydroxyl group, a carboxyl group, an amine, or an amide in an isocyanate group and a molecule of an arbitrary difunctional or higher polyfunctional polyisocyanate compound. Compounds having at least one or more isocyanate groups and one or more acryloyl or methacryloyl groups in one molecule obtained by reacting an active hydrogen group of a compound having one or more compounds can be used. Compounds having an acryloyl or methacryloyl group and at least one active hydrogen group such as a hydroxyl group, a carboxyl group, an amine or an amide in a molecule required for synthesizing this compound are available in various grades and in various grades. It is available as a commercial product. Typically, for example, as anionic monomers, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, acrylic acid, methacrylic acid, methacrylic acid, itaconic acid, crotonic acid, And any oligomers containing these compounds as copolymerization components. Examples of the cationic monomer include amide monomers such as aminoalkyl acrylate and aminoalkyl methacrylate, acrylamide, N-methylolacrylamide, dimethylaminopropyl (meth) acrylamide, and N-isopropylacrylamide. (Equation 1)
Other constituents of the resin composition containing urethane acrylate or urethane methacrylate as an essential component include polymers represented by general acrylates such as polyester-based, polyepoxy-based, polyurethane-based, polyether-based, and polyacryl-based acrylates. Prepolymers can be used.
If necessary, monofunctional and polyfunctional acrylates or methacrylates having low odor and skin irritation may be added.

In the present invention, when the active energy ray is ultraviolet light, a photosensitizer (radical polymerization initiator) must be added, and benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl Benzoin such as methyl ketal and its alkyl ethers; acetophenone, 2,
2, -dimethoxy-2-phenylacetophenone, 1-
Acetophenones such as hydroxycyclohexylphenyl ketone; anthraquinones such as methylanthraquinone, 2-ethylanthraquinone and 2-amylanthraquinone; thioxanthones such as thioxanthone, 2,4-diethylthioxanthone and 2,4-diisopropylthioxanthone; acetophenone dimethyl ketal ,
Examples include ketals such as benzyldimethyl ketal; benzophenones such as benzophenone and 4,4-bismethylaminobenzophenone; and azo compounds. These can be used alone or as a mixture of two or more. Further, tertiary amines such as triethanolamine and methyldiethanolamine; benzoic acid derivatives such as 2-dimethylaminoethylbenzoic acid and ethyl 4-dimethylaminobenzoate; It can be used in combination with a photoinitiating aid or the like. The amount of the organic peroxide and the photopolymerization initiator used is 0.5 to 100 parts by weight of the polymerizable component of the resin composition.
To 20 parts by weight, preferably 1 to 15 parts by weight.

The main constituent materials that can be used in the present invention have been described above. Next, a method for producing an active energy ray-curable aqueous resin composition will be specifically described. Representative examples of the compounding and manufacturing process of the material according to the present invention will be described step by step.

First, for synthesizing the urethane acrylate or urethane methacrylate of the formula (Chemical Formula 1), an arbitrary bifunctional polyisocyanate and a polyether diol having a structure of ethylene oxide (EO) and propylene oxide (PO) are used. According to a conventional method, these are formulated in a suitable solvent so that the ratio of the isocyanate group to the hydroxyl group becomes substantially equimolar, and they are reacted. In this case, it is preferable to formulate the composition so that the composition ratio (molar ratio) of EO and PO is in the range of 9: 1 to 4: 6. In order to convert the hydroxyl groups at both ends of the obtained polyurethane diol into acryloyl groups or methacryloyl groups, (1) m-isopropenyl-α, α-dimethyl which is a bifunctional monomer having a methacryloyl group and an isocyanate group in one molecule. A compound such as benzyl isocyanate (m-TMI) or 2-methacryloyloxyethyl isocyanate (MOI), or (2) an isocyanate group and an acryloyl or methacryloyl group and a hydroxyl group in the molecule of an arbitrary difunctional or higher polyfunctional polyisocyanate compound; At least one or more isocyanate groups and one or more acryloyl or methacryloyl groups in one molecule obtained by reacting active hydrogen groups of a compound having at least one active hydrogen group such as a carboxyl group, an amine or an amide. Is reacted with 1 mole of the polyurethane diol to obtain a bifunctional or higher-functional urethane acrylate or urethane methacrylate.

Next, the urethane acrylate or urethane methacrylate obtained by the above-mentioned method is used as an essential component, and a common polymerizable prepolymer and, if necessary, monofunctional and polyfunctional compounds having low odor and skin irritation. An active energy ray-curable aqueous resin composition is obtained by blending an acrylate or methacrylate monomer and forcibly emulsifying and dispersing the composition in water.
In this case, the urethane acrylate or urethane methacrylate prepolymer of formula 1 acts as an emulsifier. When ultraviolet rays are used as active energy rays, it is preferable that the oil-soluble photopolymerization initiator is added to the resin composition before or after emulsification, and that the water-soluble photopolymerization initiator is added after the emulsification. The emulsification method conforms to a general forced emulsification method. For example, (1) water is added after mixing all the resin components, and if necessary, a heating operation or a solvent for the resin is added, whereby the mixture is strongly dispersed with a homomixer or the like. After the dispersion, cooling, removal of the solvent, and the like are performed. (2) First, after dissolving or dispersing urethane acrylate or urethane methacrylate of the above formula (Formula 1) acting as an emulsifier in water, the remaining resin composition is gradually added with vigorous stirring. (3) It can be produced by a general phase inversion emulsification method or the like.

The resin composition of the present invention obtained by the above method may be used, if necessary, with other general-purpose aqueous resins such as polyvinyl alcohol, carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, polyacrylic acid, casein, gelatin, starch, polyvinyl It is also possible to add water-soluble resins such as pyrrolidone, polyacrylamide and derivatives thereof; and water-dispersible resins such as styrene-butadiene copolymer, polyvinyl acetate and polyacrylate. Further, an active energy ray-curable aqueous resin available as a commercial product can also be used in admixture. Further, in order to impart various functions to the resin composition of the present invention, a coloring agent, an extender, a lubricant, a plasticizer, a stabilizer, a flame retardant, an antifoaming agent, an antioxidant, and a bactericide are provided as necessary. And additives such as a conductive material and a magnetic material.

As described above, in the present invention,
By applying a coating agent mainly composed of a water-based active energy ray-curable resin having excellent affinity for the ink layer as a surface protective layer of the surface-reinforced decorative paper using the water-based ink, The adhesive strength is improved, and the resin penetrates into the paper as the base material in the heat drying process before the active energy ray curing, so that a good reinforcement of the paper layer can be achieved. Furthermore, urethane acrylate or urethane methacrylate prepolymer shown in Chemical formula 1 is used as one component of the active energy ray-curable aqueous resin composition, and the composition ratio of ethylene oxide and propylene oxide in the main chain skeleton is adjusted appropriately. By setting the ratio in such a range, the hydrophilicity / hydrophobicity is balanced, thereby imparting an emulsifying ability to other resin composition components, whereby a stable resin dispersion can be obtained. In addition, since both ends of the prepolymer molecule have an acryloyl group or a methacryloyl group, by reacting with another polymerizable resin composition component by irradiating active energy rays such as ultraviolet rays and electron beams after forming a coating film. , Works as a component of the crosslinking agent,
No unreacted components remain in the final cured coating film.

Hereinafter, the present invention will be specifically described based on examples.

[0020]

【Example】

(Example 1) <Method for producing active energy ray-curable aqueous resin composition> In step 1 and subsequent steps , all parts and percentages are by weight unless otherwise specified. After putting 250 parts of 2-butanone and 100 parts of toluene into a glass reaction vessel equipped with a calcium chloride tube, 254 parts of diphenylmethane diisocyanate was charged into the mixed solvent, and 75 parts of diethylene glycol and 40 parts of dipropylene glycol were charged. After the mixture was added dropwise over about 2 hours, the reaction was carried out for 20 hours. Dipropyl alcohol is added at the end of the reaction
And the reaction was terminated.
By adding 2 parts, a polyurethane diol in which the structures of ethylene oxide and propylene oxide were randomly incorporated at a ratio of about 7/3 was obtained. Step 2 Next, 2-methacryloyloxyethyl isocyanate 6 is added to the polyurethane diol solution obtained in Step 1.
By adding 0 parts and reacting at 60 ° C., and then removing the solvent, a bifunctional urethane methacrylate prepolymer was obtained. The disappearance of the absorption due to the isocyanate group was confirmed by IR spectrum measurement. Step 3 50 parts of the bifunctional urethane methacrylate prepolymer obtained in Step 2 was subjected to ion-exchanged distilled water 465.
And the temperature was kept at 50 ° C. To this aqueous dispersion, a prepolymer composition comprising a light- or electron-beam-curable oligomer and a monomer having the following formulation was added little by little while sufficiently dispersing with a homomixer. The prepolymer composition having the following formulation was heated to 50 ° C. and charged in a state where the viscosity was lowered. After completion of the charging, stirring with a homomixer was continued for 10 minutes at a rotation speed of 6000 rpm. A milky white uniform UV-curable aqueous resin composition was obtained. (Prescription) 6-functional urethane acrylate oligomer (Art Resin UN-3320 HC Negami Kogyo Co., Ltd.) 150 parts PO, ECH modified bisphenol A diacrylate (Epoxy ester 3002A, Sakae Chemical Co., Ltd.) 50 parts Darocure 1173 (Ciba Geigy) 7.5 parts UV-curable aqueous resin composition obtained in step 4 step 3
An aqueous UV emulsion was prepared, and an ultraviolet curable aqueous coating composition was prepared according to the following formulation. (Formulation) ・ Aqueous UV emulsion 500 parts ・ Commercially available ultraviolet-curable aqueous resin (NeoRad NR-440: 70 parts manufactured by Zeneca) ・ Polyether-modified silicone (Kp-341: Shin-Etsu Chemical Co., Ltd.) 3.5 parts ・ Silica powder (Mizukasil P-510: manufactured by Mizusawa Chemical Co., Ltd.) 6 parts ・ Water-soluble photopolymerization initiator (Irgacure 2959: manufactured by Ciba Geigy) 4 parts Silica was dispersed by the homomixer used in step 2. Milky white stable suspension A coating composition consisting of

<Production method of surface-reinforced decorative paper and decorative board>
On the aqueous ink layer of a decorative paper base material, the above-mentioned UV-curable aqueous coating agent was printed on a base paper for decorative paper having a basis weight of 60 g / m ^{2 with} an oak-like woodgrain pattern using an aqueous ink (manufactured by Toyo Ink Mfg. Co., Ltd.). After coating with a wire bar so as to have a film thickness of about 14 μm and drying in an oven at 75 ° C. for 2 minutes,
Integrated light quantity 400mJ / cm ² by 80W high pressure mercury lamp
The above coating film was cured by irradiating UV light. A hard, tough film with good surface gloss was obtained. When the decorative paper thus obtained was bonded to a particle board with a urea / vinyl acetate adhesive to form a decorative board, it had a beautiful matte coating appearance in appearance and good scratch resistance on the surface. <Evaluation method of decorative board> The performance of the decorative board obtained by the above method was evaluated by the following method. 1) Solvent resistance: Rubbing was performed under the condition of a load of 500 g / cm ² while dropping 2-butanone onto the surface of the decorative board sample, and damage to the coating film surface due to the solvent was observed. 2) Cellophane tape resistance: Peeling with cellophane tape (40 ° C. ± 3 ° C., 2) based on the standard of printed plywood / color plywood standard (Japan Print Plywood / Color Plywood Industry Association)
After an hour), the surface condition was observed. 3) Abrasion resistance: According to the JAS abrasion B test standard, sandpaper is wrapped around a rubber abrasion wheel, abrasion test is performed under the condition of a load of 500 g, and if the printed pattern disappears by 50% or more, it is rejected. , 50% or less. 4) Stain resistance: According to the standards of the JAS Soil A test, a line having a width of 10 mm is formed on the coating surface of the decorative board using an oil-based ink, a water-based ink, and crayon, left for 4 hours, wiped off with methanol, and stained. Was observed. 5) Water resistance: The coating film test piece was immersed in water at room temperature for 3 days, and the degree of whitening of the film was evaluated by visual observation. 6) Acid resistance: After dripping acetic acid (5% aqueous solution) onto the coating film, the film was covered with a watch glass, and after 6 hours, the surface state was evaluated by visual observation. 7) Alkali resistance: After dropping sodium carbonate (1% aqueous solution) on the coating film, it was covered with a watch glass, and after 6 hours, the surface condition was evaluated by visual observation. Table 1 shows the results of the characteristic tests.

Example 2 The same method and conditions as in Example 1 were used without adding a photopolymerization initiator (Darocur 1173, Irgacure 2959) to the active energy ray-curable aqueous resin composition obtained in Example 1. A coating film was formed on the aqueous ink layer of the decorative paper substrate by heating, and after heat drying, the coating film was cured by irradiating an electron beam having an acceleration voltage of 200 keV from the coating film side under the conditions of an absorption dose of 4 Mrad. . As in Example 1, a matte coating feeling on the surface was excellent, and a hard crosslinked coating film was obtained. Table 1 shows the evaluation results. (Comparative Example 1) A decorative paper was prepared in the same manner as in Example 1 except that a solvent-free electron beam-curable coating composition having the following composition was used, and the coating film was cured in the same manner as in Example 2. Decorative boards were made by performing with a wire. Table 1 shows the evaluation results. (Composition) 6-functional urethane acrylate oligomer (Art Resin UN-3320 HC, Negami Kogyo) 150 parts PO, ECH modified bisphenol A diacrylate (Epoxy ester 3002A, Kyoeisha Chemical Co., Ltd.) 50 parts Tripropylene glycol di Acrylate 90 parts ・ Polyether-modified silicone (Kp-341: manufactured by Shin-Etsu Chemical Co., Ltd.) 3.5 parts ・ Silica powder (Mizukasil 510: manufactured by Mizusawa Chemical Co., Ltd.) 6 parts

[0023]

[Table 1]

[0024]

As is apparent from the above description of the embodiment, the surface-reinforced decorative paper according to the present invention can be obtained by using a coating agent containing an active energy ray-curable aqueous resin as a main component as a surface protective layer. The adhesive strength with the aqueous ink layer is improved, and the hardening and abrasion resistance that can be used on the horizontal surface can be improved because the hardening of the paper layer can be achieved by the penetration of the curable resin component of the aqueous coating agent into the paper. The high quality decorative paper provided can be manufactured efficiently and at low cost.

Further, the resin composition used in the present invention uses water as a diluent component instead of a volatile vinyl monomer or an organic solvent, and does not generate ammonia, amine or the like upon drying. Therefore, there is an advantage that there is no problem in environmental hygiene and high-speed curing is possible by irradiation with active energy rays.

Further, bifunctional or higher functional urethane acrylate or urethane methacrylate as an emulsifier and an emulsion stabilizer used in the present invention also acts as one component of coating film curing, so that solvent resistance, water resistance, acid resistance, alkali resistance, and film strength are obtained. A cured coating film having an excellent balance of physical properties such as the above can be obtained. In addition, since this aqueous coating agent is basically a one-part type, after use, the remaining coating liquid can be reused, which is excellent in economy, and can greatly reduce equipment investment for preventing air pollution. .

Claims (5)

(57) [Claims] 1. A surface-reinforced decorative paper comprising a paper provided with a printing layer and a surface protective layer comprising a cured active energy ray-curable aqueous resin layer provided thereon. 2. The active energy ray-curable aqueous resin is a resin composition composed of an ultraviolet or electron beam-curable polymer, oligomer, monomer or the like, and at least one of the components is represented by the following formula (1). 2. The surface-reinforced decorative paper according to claim 1, comprising a bifunctional or more functional urethane acrylate or urethane methacrylate. Embedded image 3. A compound wherein the dihydric alcohol residue constituting the bifunctional or higher-functional urethane acrylate or urethane methacrylate represented by the above formula (Formula 1) is selected from ether polyols having a structure of ethylene oxide and propylene oxide. The surface-reinforced decorative paper according to claim 2, which is obtained by the following method. 4. The composition ratio (molar ratio) of ethylene oxide and propylene oxide constituting each dihydric alcohol residue of the formula (Chemical Formula 1) per each repeating unit structure is in the range of 9: 1 to 4: 6. The surface-reinforced decorative paper according to claim 2 or 3, wherein: 5. A paper is printed or colored with an aqueous ink, and a coating agent containing an active energy ray-curable aqueous resin as a main component is applied as a surface protective layer on the dried ink layer;
A method for producing a surface-reinforced decorative paper, characterized by irradiating an active energy ray after drying with heat.