JPH07102585B2 - Method of manufacturing injection molded product with pattern - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method for producing an injection-molded article with a pattern.

[Conventional technology]

As a method of forming a pattern on the surface of a molded body, a transfer sheet is superposed on the surface of the molded body and heated, and the pattern of the transfer sheet is transferred to the surface of the molded body, and the transfer sheet is provided in an injection molding mold for injection molding. There is known a method of forming a molded body to which a pattern of a transfer sheet is transferred. A transfer sheet used for this type of application generally has a structure in which a resin layer serving as a protective layer for a pattern layer after transfer, a pattern layer, and an adhesive layer are sequentially laminated on one surface of a peeling base material. A transfer sheet in which a resin layer serving as a protective layer is made of a thermoplastic resin and a transfer sheet in which a resin layer serving as a protective layer is made of a thermosetting resin are used.

[Problems to be solved by the invention]

However, when a transfer sheet in which the resin layer serving as the protective layer is made of a thermoplastic resin is used, there is a problem that the resin melts and the pattern of the pattern layer is deformed and transferred when heated above the melting point of the resin during transfer. As the temperature adjustment becomes complicated, the protective layer made of thermoplastic resin has poor chemical resistance,
There is a drawback that the protective layer and thus the pattern layer are easily attacked by an organic solvent or the like. When a transfer sheet having a thermosetting resin as a protective layer is used, a resin layer serving as a protective layer may be too hard to cause cracks during transfer or transfer a pattern to a curved surface of a molded article. Was difficult.

[Means for solving problems]

As a result of intensive studies in view of the above points, the present inventor provided a thermal transfer sheet made of an ionizing radiation crosslinkable resin in which a resin layer serving as a protective layer after transfer is crosslinked by injection molding, thereby providing a curved surface. The inventors have found that a pattern can be satisfactorily transferred to a part or the like, that the protective layer has excellent chemical resistance, and that a pattern that is not attacked by a chemical such as an organic solvent can be provided, and thus the present invention has been completed.

That is, the present invention has a resin layer which is positioned on the surface of the pattern layer after transfer and serves as a protective layer for the pattern layer, and at least the resin layer which becomes the protective layer after transfer is radically polymerizable in a resin which is decomposed by ionizing radiation. At least a transfer sheet consisting of an ionizing radiation crosslinkable resin obtained by crosslinking a resin having a saturated group introduced therein or a resin that decomposes by ionizing radiation and a mixture of a monomer having a radically polymerizable unsaturated bond in the molecule is crosslinked. On a part of the inner wall of the molding die, the release substrate side of the transfer sheet is provided in close contact with the inner wall for injection molding, and then,
A gist of a method for producing an injection-molded article with a pattern is characterized in that a molded article having a transferred pattern is obtained by peeling a release base material of a transfer sheet.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of a transfer sheet 1 used in the present invention. The transfer sheet 1 is, for example, a resin layer 3a, which serves as a protective layer after transfer onto one surface of a release substrate 2 made of a polyester film such as polyethylene terephthalate, The pattern layer 4 and the adhesive layer 5 are sequentially laminated. As the peeling substrate 2, a polyvinyl chloride film, a nylon film, an acrylonitrile-butadiene-styrene copolymer film, or the like is used in addition to the polyester film, and those having vacuum moldability and heat resistance are preferable. Further, when a material having poor releasability such as polyvinyl chloride is used as the peeling base material 2, a peeling agent layer is provided between the peeling base material 2 and the resin layer 3a which becomes a protective layer after transfer. It is preferable.

The resin layer 3a, which becomes a protective layer after transfer, is composed of a crosslinked ionizing radiation crosslinkable resin. The ionizing radiation crosslinkable resin is a resin that can be crosslinked by irradiation with electron beams, γ rays or ultraviolet rays, and is a resin that is generally decomposed by irradiation with ionizing radiation, such as polymethacrylic acid esters, polyvinylidene chloride, nitrocellulose, methylcellulose, and ethylcellulose. In the case of cellulose derivatives, polyisobutylene, etc., an electron beam by introducing a radically polymerizable unsaturated group into these resins, or by mixing with a monomer having a radically polymerizable unsaturated bond in the molecule, Crosslinking by γ-ray irradiation becomes possible. These resins can be dissolved in an appropriate solvent and applied on the surface of the peeling base material 2 to form a resin layer 3a which is crosslinked by irradiation with electron beams or γ rays. Further, by adding an ultraviolet crosslinking agent such as a carbonyl compound such as benzoin alkyl ether or benzophenone; a sulfur compound; an azo compound; a dye such as an organic peroxide to the above resin, crosslinking can be carried out by irradiation with ultraviolet rays.

Ionizing radiation crosslinkable resin is an electron beam of 0.5 Mrad to 20 Mrad,
It can be crosslinked by γ-ray irradiation.

The pattern layer 4 is formed by printing in a desired pattern using a normal printing ink, but it is preferable to use an ink having excellent adhesiveness to the resin layer 3a serving as the protective layer. It is also possible to use an ink in which the above-mentioned ionizing radiation crosslinkable resin and a pigment are dispersed in a suitable solvent. Screen printing, gravure printing, offset printing,
Gravure offset printing etc. are mentioned.

The adhesive forming the adhesive layer 5 is not particularly limited, but for example, acrylic resin, vinyl acetate resin, rubber resin, olefin resin, vinyl chloride-vinyl acetate copolymer, epoxy resin, diallyl phthalate resin or epoxy resin. Various coatings such as natural coat, reverse roll coat, gravure roll coat, air knife coat, curtain flow coat, Miyabar coat, etc. are selected from the mixture of melamine resin and acrylic resin in consideration of the adhesiveness to the transfer material. It can be formed by a printing method such as a method, gravure printing, offset printing, screen printing, offset gravure printing. The resin layer serving as the above-mentioned protective layer
The resin forming 3a can also be applied by the same method as the adhesive layer 5.

In the method of the present invention, as shown in FIG. 2, the transfer sheet 1 is formed on at least a part of the inner walls of the injection molding dies 6a, 6b, and the release substrate 2 side of the transfer sheet 1 is formed on the inner walls of the molding dies 6a, 6b. They are provided so as to be in contact with each other, and the injection molding material is injected into the molds 6a and 6b for molding. Next, the molded body thus obtained is taken out from the molds 6a and 6b, and then the peeling base material 2 is peeled off as shown in FIG. 3 to have the transferred pattern layer 4, and the pattern layer 4 is provided on the surface of the pattern layer 4. An injection molded article with a pattern 7 on which the protective layer 3 made of a crosslinked ionizing radiation crosslinkable resin is formed is obtained.

Hereinafter, the present invention will be described in more detail with reference to specific examples.

Example 1 A 25 μm-thick polyester film (Lumirror manufactured by Toray Industries, Inc.) was used as a release substrate, and a coating agent A having the following composition was uniformly applied to the entire surface of the release substrate with a gravure solid plate having a plate depth of 40 μm. The solution was applied, passed through a dry hood at 80 ° C. to evaporate the solvent, and dried.

Coating agent A composition Next, the coating agent B having the following composition is used to print a wood grain pattern on the surface coated with the coating agent A with a halftone dot gravure plate, and the solvent is volatilized through a drying hood at 80 ° C to dry the pattern. Layers were formed.

Coating agent B composition Next, an electron beam accelerated at 200 KV was irradiated with 3 Mrad to coat and dry the coating agent A and the resin layer, and the wood grain pattern layer formed by the coating agent B was crosslinked and cured. On top of this, add an ink for forming an adhesive layer having the following composition to a plate depth of 60μ.
Was uniformly applied over the entire surface with a gravure solid plate to form an adhesive layer to obtain a transfer sheet.

The transfer sheet was provided in an injection molding die, and polypropylene resin was injection molded. After cooling, the peeling base material of the transfer sheet was peeled off to obtain a polypropylene molded body having a grain pattern. Using the obtained molded product, a cotton cloth (Kanakin No. 3) soaked with ethyl acetate, toluene, methyl ethyl ketone, and ethyl alcohol was rubbed 50 times with a Gakushin-type friction tester at a load of 200 g, and a rubbing test was conducted. , No change was observed on the surface of the grain pattern.

〔The invention's effect〕

As described above, according to the present invention, a transfer sheet made of an ionizing radiation crosslinkable resin in which a resin layer serving as a protective layer for a pattern layer is crosslinked after transfer is provided on at least a part of an inner wall of an injection molding die and injection molded. By adopting the method of peeling the peeling base material of the post-transfer sheet to obtain a molded article having a transferred pattern layer, the injection molded article with a pattern obtained by the present invention has excellent chemical resistance on the surface of the pattern layer. As a result of being covered with the protective layer, the pattern layer has excellent durability and the surface strength and other physical properties are significantly improved.
Further, the transfer sheet used in the method of the present invention is composed of an ionizing radiation crosslinkable resin obtained by crosslinking a resin layer to be a protective layer after transfer, so that there is no risk of cracks in the resin layer at the time of transfer, The pattern transfer can be easily performed. Further, since the method of the present invention does not require complicated steps such as transferring ionizing radiation during or after molding, it has various effects such that an excellent injection molded article with a pattern can be efficiently produced.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is a vertical sectional view of a transfer sheet used in the present invention, and FIG. 2 is a vertical sectional view showing a state in which the transfer sheet is provided on a part of an inner wall of an injection molding die. FIGS. 3A and 3B are longitudinal cross-sectional views of a main part showing a state in which the peeling base material is peeled off after injection molding. 1 ... Transfer sheet, 2 ... Peeling base material 3a ... Resin layer to be protective layer, 3 ... Protective layer 4 ... Design layer, 6a, 6b ... Mold for injection molding 7 ... Injection with design Molded body

Claims (2)

[Claims] 1. A resin layer which is located on the surface of a pattern layer after transfer and serves as a protective layer for the pattern layer, and at least the resin layer which becomes the protective layer after transfer is radical-polymerized in a resin which is decomposed by ionizing radiation. A transfer sheet composed of an ionizing radiation crosslinkable resin obtained by crosslinking a mixture of a resin having a polymerizable unsaturated group introduced or a resin having a radically polymerizable unsaturated bond in the molecule and a resin decomposing by ionizing radiation, At least a part of the inner wall of the mold for injection molding is provided with the peeling base material side of the transfer sheet in close contact with the inner wall for injection molding, and thereafter, the pattern transferred by peeling the peeling base material of the transfer sheet. A method for producing an injection-molded article with a pattern, which comprises obtaining a molded article having 2. The method for producing an injection-molded article with a pattern according to claim 1, which comprises an ionizing radiation crosslinkable resin in which a resin layer and a pattern layer, which become a protective layer after transfer, of the transfer sheet are crosslinked.