JPH0453688B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method of inserting a transfer sheet into a mold and performing transfer simultaneously with injection molding (hereinafter abbreviated as insert molding transfer). By providing a raised pattern layer on the back side of the base sheet of the transfer sheet, a texture different from the surface of the mold is formed on the transferred surface of the molded product.

(Prior Art) Conventionally, the process of transferring to a molded product by insert molding is significantly shorter than the method of performing transfer and molding in separate processes. Low defective rate, 3
Research is progressing and it is being put into practical use because it is possible to transfer onto surfaces such as dimensional curved surfaces.

However, conventional transfer sheets only transfer the design onto the surface of the molded product, and the shape of the transferred surface depends on the surface shape of the mold. Therefore, the present inventors investigated a transfer sheet that can be textured at the same time as the transfer. The advantages of texturing using a transfer sheet are as follows.

(1) There is no need to texture the mold,
Mold making costs are lower.

(2) The shape of the texture can be changed simply by replacing the transfer sheet, and many types of textures can be obtained with one mold.

(3) It becomes very easy to match the texture and the design by transfer.

In insert molding transfer, in order to obtain a texture with a transfer sheet, the release sheet, which is peeled off after transfer, must be thick and thin to form a texture.
The following methods are available for applying this thickness to the release sheet.

(a) A raised pattern layer is formed on the transfer layer side of the base sheet, and a release layer, a colored pattern layer, and an adhesive layer are formed thereon to obtain a transfer sheet.

(b) Use a thick and thin single-layer release sheet.

(c) Form a raised pattern layer on the opposite side of the base sheet from the transfer layer.

Among these, (b) requires molding a single sheet into an arbitrary pattern, which makes it difficult to mold and makes it difficult to obtain an arbitrary shape. In addition, sheets with a low softening temperature can generally be processed such as molding, but they have drawbacks such as low heat resistance and breakage during transfer during insert molding, or fusion to molds or molded objects. On the other hand, method (a) can be easily obtained by providing a raised pattern layer on a uniform sheet, and the raised pattern layer can also be formed arbitrarily by a simple method such as a printing method. Furthermore, in (a), it is necessary to form a transfer layer such as a release layer on top of the raised pattern layer, and it is necessary to form these layers on an uneven surface without defects. In order to achieve stable peeling at the interface, there are problems such as the material of the raised pattern layer being limited.

On the other hand, the transfer sheet with the structure (c) was conventionally used for the method of layering the molded product and applying heat and pressure from the back side using a heating plate or heating roll. Texture reproduction is poor due to the base sheet in between.

However, according to studies by the present inventors, if this is used for the above-mentioned insert molding transfer, the base sheet will be sufficiently softened by the heat of the molten resin, and the injection pressure of the resin will not affect the transfer sheet regardless of its unevenness. It was found that because the transfer sheet was applied uniformly over the entire surface, the transfer sheet was sufficiently deformed and had excellent texture reproduction.

(Structure) The structure of the transfer method of the present invention will be explained. Transfer sheets generally consist of two parts: a transfer layer that is transferred to the object to be transferred and forms patterns and various colors on its surface, and a base sheet that holds this layer in the form of a transfer sheet and is peeled off after transfer. It's working. Furthermore, the transfer layer is divided into layers having different functions, such as a release layer, a colored pattern layer, and an adhesive layer, starting from the base sheet side. The release layer has the function of closely adhering the transfer layer to the base sheet without falling off when it is in the form of a transfer sheet, and easily peeling it off from the base sheet during transfer. The colored pattern layer is a part that forms a pattern or a colored layer, and sometimes has a concealing function so that the color of the pattern or colored layer is not affected by the color of the transfer object. The adhesive layer has the function of adhering these transfer layers to the object to be transferred and bringing them into close contact with the surface of the object to be transferred.
Various plastic films such as polyethylene, polypropylene, polyester, polyacrylic ester, polyamide, polyvinylidene chloride, ethylene vinyl acetate copolymer, cellophane, etc. can be used as the material for the base sheet, and each can be used alone or in combination. . Furthermore, silicone,
Mold release treatment may be performed using a mold release agent such as wax or a curable resin such as melamine resin, aminoalkyd resin, or unsaturated polyester resin. The transfer layer is mainly composed of resin, such as phenol, melamine, alkyd, diallyl phthalate, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl acetal, polystyrene, and polyacrylic ester. , chlorinated polypropylene, chlorinated polyethylene, polyamide, natural rubber and its derivatives, cellulose resins, and resins to which extender pigments such as silicon dioxide, calcium carbonate, barium sulfate, and titanium white are added can be used. . As the coloring agent, organic pigments such as azo pigments such as Lake Red 4R, Fast Yellow G, and Benzidine Yellow G, azo lake pigments such as Lake Red C, Lake Red D, Brilliant Scarlet G, and Brilliant Carmine 6B, phthalocyanine blue, and phthalocyanine can be used. Phthalocyanine pigments such as green, Industhrene Violet RH, Induslin Direct Black B, Industhrene Brilliant Orange GR, Industhrene Brown BR, Industhrene Scarlet RB, Industhrene Orange
Threnic pigments such as RRT, Industhrene Orange RRTP, Alizarin Lake, Quinacridone pigments such as Sinclair Sheared, Dioxane pigments such as PV Fast Violet BL, Acid dye lake pigments such as Green Gold, Auramine Lake. Basic dye lake pigments such as Yellow O, nitro pigments such as naphthol yellow, architectural dye pigments, mordant dye pigments, nitro pigments, and inorganic pigments such as titanium white, carbon black, deep blue, ultramarine, Examples include iron oxide and alumina white. Then, appropriate additives such as surfactants and anti-abrasion agents are added to the above resins, or resins with extender pigments and coloring pigments added, and intaglio printing is carried out.
Printing methods such as letterpress printing, stencil printing, lithographic printing,
The transfer layer is formed by a coating method such as gravure coating, roll coating, kiss coating, knife coating, air knife coating, rod coating, spray coating, or extrusion coating.

The transfer sheet of the present invention has an arbitrary raised pattern layer formed on the surface of the base sheet of the transfer sheet opposite to the transfer layer as described above. This raised pattern layer may be formed before, during or at the same time as forming the transfer layer on the base sheet, and the most suitable method for forming it is intaglio printing, letterpress printing, stencil printing, lithographic printing, etc. In particular, the thicker the raised pattern layer, the greater the texture effect, so intaglio printing and stencil printing are effective. In addition, a method of pasting sheets with thick and thin patterns, such as sheets with holes, woven cloth, etc., can also be considered.
However, in this case, the raised pattern on the transfer sheet and the surface shape of the molded product obtained by injection molding have a male-female relationship; that is, the convex portions on the transfer sheet become concave portions of the molded product, and the concave portions on the transfer sheet become concave portions of the molded product. It is necessary to take into account that there will be a convex part on the product.

Since the base sheet generally has a thickness of 20 μm or more, the thickness of the raised pattern layer must be 5 μm or more in order to sufficiently reproduce the texture.

The transfer sheet is placed on the inner surface of a well-known plastic injection mold, and the plastic is injection molded and laminated. The plastic is, for example, ABS resin, and injection molding may be performed by a known method. After lamination, the base sheet can be peeled off together with the raised pattern layer to obtain a molded article with reproduced texture.

(Function) As described above, by inserting the transfer sheet of the present invention into a mold and performing injection molding, it is possible to form a pattern and a texture on the molded product at the same time, which was previously difficult. This makes it possible to easily obtain molded products with a variety of different types at low cost.

(Example) A raised pattern layer was formed as follows on a hot stamp foil for an ABS resin molded product with a cedar grain pattern using a 25μ thick polyester film as a base sheet.

●Varnish; Dianal LR-469 Polyacrylic acid ester resin manufactured by Mitsubishi Rayon Co., Ltd. 62 parts by weight Calcium carbonate 18 Toluene 15 Ethyl acetate 15 Total 110 parts by weight● Printing method: Gravure printing method - Thickness of raised pattern: Approximately 10 μm (after drying) The raised pattern layer was formed in the shape of a spring wood pattern so as to match the cedar spring wood portion of the hot stamp foil used.

The transfer sheet produced in this way was inserted into a mold for producing a board with a smooth surface so that the raised pattern of the transfer sheet was in contact with the mold, and then an ABS resin board was produced by injection molding. .
Then, when the base sheet was removed from the mold and the base sheet was peeled off, the surface of the ABS resin plate was similar to that of a floating process in which the spring wood part of the grain pattern of cedar became a concave part. A decorative board with an appearance of

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the configuration of a transfer sheet according to the present invention, Fig. 2 is a sectional view showing the state inside the mold after the transfer sheet is inserted into a mold and resin is injected, and Fig. 3 1 and 2 respectively show cross-sectional views of the molded product after the molded product has been taken out from the mold after injection molding and the base sheet has been peeled off. 1... Raised pattern layer, 2... Base sheet, 3
...Peeling layer, 4...Colored pattern layer, 5...Adhesive layer,
6... Transfer layer, 7... Injection molding resin, 8... Injection mold.

Claims (1)

[Claims] 1 On one side of the base sheet, a release layer, a colored pattern layer,
Adhesive layers are sequentially applied to the other side of the base sheet to a thickness of 5 μm.
A transfer method comprising placing a transfer sheet having a raised pattern layer of m or more in length in a mold, injecting resin from the adhesive layer side to mold the sheet, and then peeling and removing the base sheet.