JPS6333790B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a top coating agent for various types of decorative sheets, and more specifically, to an aqueous top coating agent suitable for surface protection and beautification when applied to a decorative surface in a method for producing various types of decorative sheets.

A large number of decorative sheets have been manufactured in the past, but these decorative sheets are made by applying various types of printing to a substrate sheet, then applying an oil-based paint, mainly an aminoalkyd type, and baking it to harden it to form a top layer. In these conventional top coating agents, the first
The first disadvantage is that a relatively high temperature is required for curing the top coating agent, the second disadvantage is that a large amount of solvent vapor is generated during drying, and the third disadvantage is that the top coating agent is difficult to form. The coated film surface has a strong tacky feel with glare, and even if a matte pigment is used in combination, it is not possible to create a natural surface like that of natural wood.

Furthermore, recently, three-dimensional patterns have been formed by forming the conduit portion of the woodgrain pattern into a concave shape, but in the case of conventional top coating agents, when using the known polymerization delay method or liquid coating method, it is difficult to cut the concave portion. There are drawbacks such as insufficient processing and the need for multiple treatments.

As a result of intensive research to solve the above-mentioned drawbacks of the prior art, the present inventor has found that when using a certain type of water-soluble resin paint as a top coating agent in the production of decorative sheets, the above-mentioned many drawbacks can be sufficiently overcome. The present invention was completed after discovering that the problem was solved and an excellent decorative sheet could be obtained.

That is, the present invention comprises 50 to 80 parts by weight of a water-soluble melamine resin, 5 to 10 parts by weight of a matting agent, 1 to 15 parts by weight of a curing catalyst, and the remaining part by weight of an aqueous medium, when the total amount is 100 parts by weight. This is a top coating agent for decorative sheets, characterized in that the main component of the water-soluble melamine resin is polyethylene glycol-modified methylol melamine.

To explain the present invention in detail, the water-soluble melamine resin used in the present invention and which mainly characterizes the present invention is methylolmelamine having 3 to 6 methylol groups/mol modified with polyethylene glycol having a molecular weight of about 100 to 5000. It is a water-soluble resin obtained by . The curing catalyst is a catalyst for crosslinking the melamine resin, and any of various organic or inorganic acidic substances can be used, but para-toluenesulfonic acid is particularly preferred in the present invention. In addition, the aqueous medium is one that has water as its main component and may also contain other water-miscible organic solvents such as alcohols.

The essential components of the top coating agent of the present invention are as described above, but in addition to the above components, the top coating agent of the present invention also includes titanium oxide, iron oxide (yellow ocher, Bengara, iron black, etc.), polyazo, phthalocyanine blue, etc. , phthalocyanine green, quinacridone, and other various additives may be added and mixed as necessary.

In particular, by incorporating about 0.5 to 2% by weight of a silicone coating agent into the top coating agent of the present invention, the removability of the final decorative sheet product with cellophane tape can be significantly improved.

The aqueous top coating agent of the present invention exhibits particularly remarkable effects when used as a top coating agent for various decorative sheets.

In other words, conventional aminoalkyd-based oil-based top coating agents were selective to base sheets for decorative laminates and printing inks for printing wood grains and other patterns, but the top coating agent of the present invention is selective to such substrates and printing inks. It has the advantage that there is no ink selection and it can be used with any substrate or in combination with printing inks.

Furthermore, since the top coating agent of the present invention is water-based, it does not require pre-drying or high curing temperatures unlike conventional top coating agents, and it also generates less solvent vapor, which is advantageous in terms of equipment. A particularly remarkable effect is that by using a small amount of matting agent, the surface of the coating film can have a natural feel similar to that of natural wood.

On the other hand, in the case of conventional top coating agents, the texture of the coating surface is too strong, and if a large amount of matting agent is used to weaken this texture, the applicability becomes poor, and the too strong texture is resolved. It was something I couldn't do. In addition, when used in the production of conventional decorative sheets with three-dimensional patterns that utilize polymerization retardation and repelling phenomena, in the case of conventional top coating agents, the top coating agent is applied, pre-dried to form concave portions, and then heated at a high temperature. However, when the top coating agent of the present invention is used to form the concave portions by a chemical method such as a polymerization retardation method or a repelling method, Since the top coating agent is water-based, the recesses are sharp and do not require pre-drying, and the coating is formed at a relatively low temperature, making it possible to form very sharp recesses without the recesses collapsing. It has the advantage that, in particular, it can provide sufficient resistance to cellophane tape peeling with one application.

Next, to explain the method for producing a decorative sheet using the top coating agent of the present invention, the base sheet to be used may be one of conventionally known materials, such as various types of paper, processed paper, cellophane, polyethylene, polyester, and other synthetic materials. resin film or sheet,
Any of metal materials such as aluminum foil, aluminum sheet, and steel plate, various types of wood, plywood, and laminates thereof can be used.

Of course, such a base sheet may be treated with various base paints or impregnating agents as necessary.

Next, an arbitrary pattern is printed on the base sheet as described above, but the printing ink for such printing can be the normal printing ink conventionally used in the production of decorative laminates. can. Further, the printing method may be any printing method such as gravure printing.

The top coating agent of the present invention is applied onto the printing base sheet obtained as described above,
When producing a three-dimensional decorative sheet in which recesses are formed in the top coat layer, a substance that retards the polymerization hardening of the top coat agent (for example, a polymerization inhibitor or a polymerization retardant) is added to the patterned portion of the printed surface where the recesses are to be formed. It is necessary to synchronize printing with a printing ink (for example, a melamine alkyd printing ink) containing a substance (for example, a silicone-based detergent) that binds the top coating agent and the top coat agent.

In such cases, the present inventors believe that when using the top coating agent of the present invention, alkaline substances are preferred as polymerization inhibitors or retarders, and alkaline earth metals of higher fatty acids such as calcium stearate are preferred as retarding agents. We have found that salt is particularly effective.

That is, since the top coating agent of the present invention is aqueous, it quickly acts with the polymerization inhibitor or retardant, and is quickly absorbed by the alkyl group of the higher fatty acid salt.

Furthermore, if necessary, the printed base sheet as described above or the specially printed base sheet as described above can be transferred to the next step as is, but if the base sheet is an impregnable material such as paper or processed paper. In such cases, by impregnating these printing base sheets with a resin impregnating agent such as acrylic resin, urea resin, or melamine resin before top coating, the peel strength of the printing in the concave areas formed after top coating can be significantly improved. We also found that it is possible to significantly increase

Next, the top coating agent of the present invention is applied to the printing base sheet as described above.
It can be applied using any method such as a gravure coater, air knife coater, flow coater, or spray coater, and the amount of application is about 5 to 20 g/solid content.
Preferably, it is ^m2 . There is no need to pre-dry the coating after application; for example, the desired decorative board can be obtained by heat treatment at a temperature of about 100 to 150° C. for about 30 seconds to 2 minutes. Contrary to expectations, the decorative board obtained in this way has excellent surface strength, and its surface does not have a harsh, artificial, or shiny texture, and has a feel similar to that of very good natural wood. In addition, in the case of a three-dimensional decorative sheet having concave portions in the surface layer, the notches in the concave portions are sharp, giving a more natural look than when conventional top coating agents are used. Ta.

Next, the present invention will be explained in more detail with reference to Examples. In the text, parts or percentages are based on weight unless otherwise specified.

Example 1 60 parts of polyethylene glycol-modified methyl etherified methylol melamine resin (polyethylene glycol molecular weight approximately 1000), 5 parts of matting agent (Syroid 162), 5 parts of para-toluene sulfonic acid, 1 part of water-dispersible silicone polishing agent, and water. 30 parts were mixed to obtain a top coating agent for decorative laminates () of the present invention.

Example 2 Polyethylene glycol modified methylol melamine resin (polyethylene glycol molecular weight approximately 700)
60 parts of a matting agent (Thyroid 162), 5 parts of para-toluenesulfonic acid, and 27 parts of water were mixed to obtain a top coat agent for decorative laminates () of the present invention.

Example 3 Nitrocellulose 15 was applied to thin paper with a basis weight of 50 g/ ^m2.
Solid printing, blur printing, pattern printing, and accent printing were performed using a gravure printing method using a conventional printing ink consisting of 40 parts of pigment, 40 parts of pigment, and 45 parts of solvent. The aqueous top coating agent of Example 1 was applied to the entire surface of this printing paper using a gravure coating method at a rate of 10 g/m ² (solid content), and dried and cured at 150° C. for 30 seconds.

The surface of the obtained decorative sheet was cleanly leveled without uneven penetration of the top coat agent. When this decorative sheet was laminated to the surface of a particle board using a urea resin adhesive at 150° C., 5 kg/cm ² and for 90 seconds, an excellent decorative board was obtained.

Example 4 Solid printing and blur printing were performed on titanium base paper with a basis weight of 100 g/m ² using a gravure printing method using a conventional gravure ink consisting of 5 parts of cellulose acetate, 20 parts of pigment, and 75 parts of solvent.

Next, a printing ink consisting of 20 parts of styrene maleic acid resin, 30 parts of pigment, 20 parts of triethanolamine, 20 parts of water, and 10 parts of ethylene glycol is used to perform gravure printing on the areas on the surface of this printing paper where concave portions are to be formed. I printed using this method.

After thoroughly drying the printing ink, apply the top coating agent of Example 2 to the entire printed surface using a reverse coater.
Apply at a rate of 20g/m ² (solid content) and 60g/m2 at 150℃
It was heated and cured for seconds.

The decorative sheet obtained had an excellent natural wood texture, and the conduit portions of the pattern were sharp with sharp cuts.

In addition, the decorative sheet is coated with a urea resin adhesive.
When laminated to particle board under the conditions of 150°C, 5 kg/cm ² and 90 seconds, an excellent embossed decorative board was obtained.

Example 5 Nitrocellulose 15 was applied to thin paper with a basis weight of 30 g/ ^m2 .
Solid printing and blur printing are performed using a gravure printing method using a conventional printing ink consisting of 40 parts of pigment and 45 parts of solvent, and then 20 parts of melamine resin and 10 parts of alkyd resin are applied to the areas of the printing paper where the recesses are to be formed.
Printing was carried out using a gravure printing method using a printing ink consisting of 10 parts of pigment, 45 parts of solvent, 5 parts of para-toluenesulfonic acid, and 10 parts of silicone polishing agent.

Next, the top coating agent of the present invention according to Example 1 was applied to the entire surface of the above printing paper using a gravure coating method at a rate of 10 g/m ^{2 .}
(solid content) and dried and cured at 150°C for 30 seconds.

The surface of the obtained decorative sheet had an excellent natural wood feel without being too tacky, and the conduit portions of the pattern were sharp with sharp cuts.

In addition, the decorative sheet was heated at 150℃ using a urea adhesive.
When laminated to the surface of a particle board under conditions of 5 kg/cm ² and 90 seconds, a decorative board with an excellent wood feel was obtained.

Example 6 Blur printing was carried out on a titanium base paper with a basis weight of 80 g/m ² using a gravure printing method using a conventional gravure ink consisting of 5 parts of cellulose acetate resin, 20 parts of pigment, and 75 parts of solvent.

Next, add 10 parts of water-soluble resin and 10 parts of calcium stearate to the part of the surface of the printed matter where the concave part is to be formed.
Printing was carried out using a gravure printing method using printing ink consisting of 70 parts and 70 parts of water.

After drying the printing ink, the printing paper was impregnated with an acrylic resin impregnating agent, and after drying, the top coating agent of the present invention of Example 2 was applied to the entire printed surface at a rate of 20 g/m ² (solid content) using a reverse coater. Then, when the same treatment as in Example 6 was carried out, a decorative board having excellent natural wood feel and unevenness as in Example 6 was obtained.

Claims (1)

[Claims] 1 When the total amount is 100 parts by weight, it consists of 50 to 80 parts by weight of a water-soluble melamine resin, 5 to 10 parts by weight of a matting agent, 1 to 15 parts by weight of a curing catalyst, and the remaining part by weight of an aqueous medium. A top coating agent for decorative sheets, characterized in that the main component is polyethylene glycol-modified methylolmelamine.