JPH0437508A - Decorating method of three-dimensional formed item - Google Patents

Abstract

PURPOSE:To stably mass-produce the desired pattern and design by a method wherein a base material sheet having the desired pattern thereon is preformed into the shape along the predetermined mole surface of a casting mold and, after that, placed on the mold surface of the casting mold so as to pour resin in the mold and harden the resin. CONSTITUTION:Transparent acrylic film 1, onto which pattern 2 is printed in photogravure, is softened by heating with a heater and, after that, formed in the reverse shape of a washbowl by vacuum forming technique. Transparent polymerizable resin 4 is cast in a stainless steel casting mold 3 having the same shape as the reverse mold of the washbowl. The formed film 1 is placed on the transparent polymerizable resin layer 4. Under the condition just mentioned above, contact bonding and deaeration of the assembly of the casting mold 3, the resin layer 4 and the film 1 are carried out. Further, base polymerizable resin 5 is cast on the resin layer 4 and hardened by heating. Thus, three-dimensional formed item having the desired pattern and design can be stably mass-produced. Further, since the base material sheet, which has been formed with a separate mold, is installed on the casting mold, no suction hole mark of the forming mold or the like is left on the formed item, offering an attractive product.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for painting a three-dimensional resin molded article, and particularly to a method for painting a three-dimensional molded article that is effective when molding a three-dimensional molded article by cast molding.

[Conventional technology]

Conventionally, as a method of painting and applying patterns to three-dimensional cast molded products such as artificial marble, natural stone powder, colored particles, glitter particles, etc. are mixed into polymeric resin.
A method to express a painting with a stone pattern, a method to obtain a marble-like pattern by unevenly mixing coloring materials (pigments, dyes) in a polymeric resin, a method to create a coloring range different from the base color range, A known method is to mix the ingredients uniformly and then change the pouring direction of the mold during casting to obtain a marble-like pattern. However, with any of these methods, it is difficult to stably obtain designs, patterns, and patterns.
In addition to drawbacks such as insufficient stability of color tone during mass production, it also depends on the quality of the pattern and the skill level of the individuals involved, making it difficult to consistently obtain uniform products. It was difficult.

[Problem to be solved by the invention]

The present invention eliminates the above-mentioned drawbacks of the conventional painting method for cast molded products, and provides a method for producing three-dimensional molded products by cast molding, which allows desired patterns and designs to be stably obtained in large quantities. The purpose of painting is to obtain a method.

[Means to solve the problem]

In order to solve the above problems, the present invention preforms a base material sheet having a desired pattern into a shape along a predetermined mold surface of a casting mold, and applies the preformed base material sheet to a casting mold. After being placed on the mold surface, the resin three-dimensional molded product is painted in a desired manner by injecting a resin into the casting mold and curing the resin. Furthermore, in the present invention, for the purpose of protecting the pattern surface, a resin layer is applied to the mold surface of the casting mold before installing the preformed base material sheet on the mold surface of the casting mold. The method may further include the step of forming a surface protective layer for the pattern by placing a preformed base sheet on the resin layer. Furthermore, it is particularly desirable to use a polymeric resin as the resin injected into the casting mold.

The painting method according to the invention is particularly effective when used for painting decorative artificial marble, and can also be used for painting many other types of resin three-dimensional shapes, such as wash basins and bathtubs. It is possible. The resins used include pigments, dyes,
Polymerizable resins (polymerizable syrup) mixed with fillers, polymerization initiators, etc. are preferred, and methyl methacrylate resins and polymers thereof, or unsaturated polyester resins and derivatives thereof are particularly preferred.

The base sheet is made of acrylic, vinyl chloride, polyester,
Thermoplastic resins such as acrylic styrene and acrylonitrile butadiene styrene are preferred.

Further, it is desirable from the viewpoint of improving adhesiveness that the SP values of the base sheet and the polymerizable resin are similar.

Furthermore, depending on the product to be molded, it is possible to omit the surface protective layer, and the base sheet may be transparent or
It is desirable to use a semi-transparent material because it makes the pattern easier to see.

As the casting mold used in the present invention, conventionally known molds can be used, such as FRP molds, stainless steel molds, aluminum molds, and epoxy molds.

Materials used for the base sheet include polyethylene film, polypropylene film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, polyethylene terephthalate film, polycarbonate film, nylon film, polystyrene film, and ethylene vinyl acetate film. polymer film,
Examples include ethylene vinyl alcohol copolymer film, ionomer plastic film, and acrylic film.

As a means for imparting a pattern to the base sheet, printing means can be used, and advantageous printing methods include intaglio printing such as gravure and gravure offset, letterpress printing such as letterpress and flexography, and lithographic printing such as lithographic offset. , stencil printing such as silk screen printing, die litho printing, electrostatic printing, inkjet printing, and the like.

Various molding methods can be used to pre-form a decorative sheet with a desired pattern on the base sheet into a mold having the same shape as a casting mold, such as vacuum molding, vacuum-pressure molding, and press molding. Various molding means using heat and/or pressure can be used. Moreover, the shape of the mold used for preliminary molding is the same as that of the casting mold.

The ink used for printing is prepared by appropriately mixing a vehicle with coloring agents such as pigments and dyes, extender pigments, solvents, stabilizers, plasticizers, catalysts, curing agents, etc., as necessary. The vehicle is appropriately selected from among thermoplastic resins, thermosetting resins, ionizing radiation-curable resins, etc. depending on the application, required physical properties, printability, etc.

Examples of thermoplastic resins include cellulose derivatives such as ethyl cellulose, cellulose nitrate, cellulose acetate, ethyl hydroxyethyl cellulose, and cellulose acetate propionate, styrene resins or styrene copolymers such as polystyrene and polyα-methylstyrene, and polymethyl methacrylate. , acrylic resins such as polyethyl methacrylate, polyethyl acrylate, polybutyl acrylate,
Vinyl polymers such as polyvinyl chloride, polyvinyl acetate, vinyl chloride/vinyl acetate copolymer, polyvinyl butyral, rosin, rosin-modified maleic acid resin, rosin-modified phenol resin, rosin ester resin such as polymerized rosin, coumaron resin, vinyl Natural or synthetic resins such as toluene resin and polyamide resin can be used.

Thermosetting resins include phenol resin, urea resin, diallyl phthalate resin, melamine resin, guanamine resin, unsaturated polyester resin, polyurethane resin, epoxy resin, aminoalkyd resin, melamine/urea cocondensation resin, silicone resin, There are polysiloxane resins, etc., and if necessary, curing agents such as crosslinking agents and polymerization initiators,
Add polymerization accelerators, solvents, viscosity modifiers, extender pigments, etc.

As curing agents, isocyanates are usually used for unsaturated polyester resins and polyurethane resins, amines are used for epoxy resins, peroxides such as methyl ethyl ketone peroxide, radical initiators such as abbis isobutyronitrile, or unsaturated polyester resins are used. Commonly used in resins.

As the isocyanate, an aliphatic or aromatic isocyanate having a valence of two or more can be used, but aliphatic isocyanates are preferable from the viewpoint of prevention of thermal discoloration and weather resistance. Specific examples include tolylene diisocyanate, xylene diisocyanate, 4,4-diphenylmethane diisocyanate, l
Examples include xamethylene diisocyanate and redane diisocyanate.

Further, in order to accelerate the curing reaction, heating may be performed after coating, if necessary. For example, in the case of incyanate-cured urethane-curable unsaturated polyester resins or polyurethane resins, it is usually kept at 40 to 60°C for about 1 to 5 days, and in the case of polysiloxane resins, it is usually kept at 80 to 150°C for about 1 to 30 days.
It takes about 0 minutes.

It is possible to use an ionizing radiation-curable resin, in which case a composition containing an appropriate mixture of prepolymers, oligomers, and/or monomers having polymerizable non-bonds or epoxy groups in the molecule is used. .

In this case, ionizing radiation refers to electromagnetic waves or charged particle beams that polymerize and crosslink molecules and have L energy quantum.

Transparent, semi-transparent polymeric resin (surface protective layer) for casting molds
Various coating methods such as pour coating, brush coating, and spray coating can be used to provide the coating.

Pouring, hollow molding, and low-pressure injection can be used to inject the mixed polymeric resin (base resin) into the casting mold.

Moreover, as mentioned above, the polymerizable resin used in the present invention is preferably methyl methacrylate resin and its polymer, or unsaturated polyester resin and its derivative. Acrylic resins include homopolymers of methyl methacrylate and methyl methacrylate and α and β.
Copolymers with ethylenically unsaturated compounds are typical, but other polymers of (meth)acrylic acid or its esters can also be used. Examples of monomers constituting the above polymer include vinyl acetate, styrene, methyl (
Mention may be made of meth)acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, ethyl methacrylate, butyl methacrylate and cyclohexyl methacrylate. As the polyester resin, various kinds of known ones used for FRP, artificial marble, etc. can be used. For example, an unsaturated alkyd containing an α-β unsaturated polybasic acid as one component, modified with any saturated acid and/or unsaturated acid, and obtained by an esterification reaction with a polyhydric alcohol is dissolved in a solution. type, bisphenol-based unsaturated polyester resin, isophthalic acid-based unsaturated polyester resin, etc. can be used.

The polymerization initiator is commonly used as a catalyst for syrup.
Peroxy compounds, hemibarmaleates (eg mono-tert-butyl peroxymaleate) are preferred.

Curing agents include ethylene dimethacrylate, propylene dimethacrylate, polyethylene glycol dimethacrylate, divinylbenzene, triallyl cyanurate and diallyl phthalate.

Fillers include aluminum hydroxide, magnesium carbonate, barium sulfate, calcium sulfate, alumina, stone powder, and FRP.
Select from among waste materials, silica sand, glass fiber, clay, kaolin, and talc, taking into consideration the impact on aesthetics and product strength.

The present invention achieves the required initial objectives under the above conditions. Furthermore, in the present invention, in addition to the pattern layer, if necessary, on one side or both sides of the base sheet,
A more stable molded product can be obtained by providing a primer layer made of urethane paint or the like for the purpose of improving adhesion to the surface protective layer and the polymeric resin that is the base resin layer. In addition, in order to improve the adhesion between the base sheet and the polymeric resin and obtain a better product, it is highly desirable to have the solubility parameter and the SP value of the base sheet/polymerizable resin match or have similar values. That's true.

[Effects of invention]

According to the present invention, it is possible to mass-produce three-dimensional molded products having stable desired patterns and designs by casting. In addition, since the moldable base sheet is completely molded in a separate mold before being attached to the casting mold, even complex three-dimensional shaped casting molds can be molded without wrinkles or tears. It can be installed in a perfectly aligned state, and no traces of the air intake holes of the vacuum or pressure molding mold remain on the molded product, making it possible to obtain a final product with a good appearance.

〔Example〕

Hereinafter, the invention will be explained in more detail with reference to some embodiments based on the accompanying drawings.

[Example 1] 1. A marble pattern 2 was printed by gravure printing on a transparent acrylic film J having a thickness of 100 μm. Acrylic ink was used as the printing ink.

2. The printed film was softened by heating with a heater and molded into the reverse shape of a washbasin bowl using a vacuum molding method.

3. Stainless steel casting mold 3 with the same shape as the reverse washbasin pole mold
A transparent polymerizable resin (surface protective layer) 4 having the following compounding ratio was poured into the sample by a flow method to a thickness of about 1 m/m.

Blending ratio: 100 parts of polymerizable solids of methyl methacrylate (manufactured by Mitsui Toatsu Chemical Co., Ltd.) t-butyl baroquinoneodecanoate
1 part 4, and 2 parts on the transparent polymerizable resin layer 4.
．． The molded film was placed, and pressure was applied using a hand roller to remove air.

5.Furthermore, 4. Base polymerizable resin 5 having the following blending ratio was poured from above by the flow method to a thickness of about 100 to 150 m/m.

Blending ratio: Polymerizable slag 11 of methyl methacrylate
30 parts (manufactured by Mitsui Toatsu Chemical Co., Ltd.) Silica sand 30 parts Aluminum hydroxide powder 40 parts (manufactured by Showa Denko Co., Ltd.) t-Butylperoquinoneodecanoute
The 0.3 part curing conditions were 70°C, 1 hour, pre-cure, -120°C, 1 hour, after-cure.

[Example 2] 1. 150μ thick transparent PVC film (plasticizer 12pt)
(R)] was printed with marble pattern 2 by gravure printing.

PVC acrylic ink was used as the printing ink.

2. Next, an easy-adhesion brimer 6 (see FIG. 2) made of urethane paint was applied to both sides of the film to a thickness of 2 μm by gravure coating.

3.2. The printed film was formed into the reverse shape of a washing bowl by vacuum forming.

4. A transparent polymerizable resin having the following blending ratio was poured into a FRP casting mold 3 having the same shape as the inverted washbowl mold by a flow method to a thickness of about 1 m/m (surface protective layer 4).

Silica sand aluminum hydroxide powder (manufactured by Showa Denko K.K.) 50 parts 50 parts Blending ratio: Unsaturated 11J ester resin 10
0 parts (manufactured by Showa Kobunshi Co., Ltd.) Cobalt naphthenate (accelerator)
0.1 part methyl ethyl ketone peroxide (curing agent) 0.3 part 5, 3 on the transparent polymerizable resin layer 4
．． The molded film was placed, and pressure was applied using a hand roller to remove air.

6.Furthermore, 5. Base polymerizable resin 5 having the following blending ratio was poured from above by the flow method to a thickness of about 100 to 150 m/m.

Blending ratio: unsaturated polyester resin 100
(manufactured by Showa Kobunshi Co., Ltd.) Cobalt caftenate (accelerator)
0.1 part Methyl ethyl ketone peroxide (curing agent) 0.3 part Curing conditions: room temperature (20°C) 12
It was time.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a step in which a three-dimensional molded article is cast according to the method of the present invention, and FIG. 2 is a diagram showing a state in which an easily adhesive brimer layer is applied to a molded sheet.

Claims (1)

[Claims] 1. A method for painting a cast three-dimensional molded product, which involves pre-molding a base sheet having a desired pattern into a shape along a predetermined mold surface of a casting mold, and After placing a preformed base material sheet on the mold surface of a casting mold, a resin is injected into the casting mold and cured, whereby a desired painting is applied to a resin three-dimensional molded product. How to do it. 2. Before installing the preformed base material sheet on the mold surface of the casting mold, a resin layer is formed on the mold surface part of the casting mold, and the preformed base material is placed on the resin layer. 2. The painting method according to claim 1, further comprising the step of forming a surface protective layer for the pattern by placing the sheet. 3. The painting method according to claim 1 or 2, wherein the resin injected into the casting mold is a polymeric resin.