JPH07299996A - Transfer sheet - Google Patents

Abstract

PURPOSE:To provide a transfer sheet wherein a crack, crazing, or collapse of a pattern or the like are not generated in a transfer layer, the transfer layer does not peel off from a substrate sheet, even though it is formed by stretching at ordinary temperature. CONSTITUTION:In a transfer sheet composed by laminating at least a decorative layer 4 on a base material sheet 1, the decorative layer 4 has 5-150% of elongation at rupture at ordinary temperature, and as the base material sheet 1 it can follow elongation of the decorative layer 4. After a transfer sheet S is subjected to a coat-forming to a material to be transferred at ordinary temperature along its irregular shape by vacuum forming or vacuum and pressure forming, an adhesive property of a transfer layer is developed by pressing or heating with a heating rubber, and the transfer layer is bonded to the material to be transferred. The transfer sheet can execute decoration of a curved surface of a three-dimensional molded product without generating any crack by following its irregularity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a case where a vacuum press transfer method is used to decorate and decorate the outer surface of a base (transfer target) having a three-dimensional shape such as a cabinet of light electric equipment and an interior member of an automobile. The present invention relates to a transfer sheet used in.

[0002]

2. Description of the Related Art Generally, a transfer sheet of this type has a structure in which a release layer, a decorative layer, an adhesive layer, etc. are laminated on a base material sheet, and roll transfer or up-down transfer is performed on the surface of a transfer target already formed. There are an after-transfer sheet used for decorating by transfer and an in-mold transfer sheet used for transferring at the same time when the transfer target is molded.

[0003]

The former transfer sheet described in the prior art has the following problems. The decorative surface is limited to a two-dimensional plane or a cylindrical side surface, and it is not possible to transfer and paint on a three-dimensional base body (transfer target) having a diaphragm or the like. When the transfer sheet is stretch-molded at room temperature, the transfer layer is peeled off from the base material sheet, and the design failure such as cracking or collapse of the transfer layer occurs.

On the other hand, the latter transfer sheet has the following problems. It is used in a system that decorates simultaneously with injection molding, resulting in poor productivity and high cost. Since the molded products that have already been molded cannot be decorated, they cannot be re-decorated and the yield is poor. The size of the molded product is limited. If the transfer sheet is not heated and softened as a pre-transfer operation, cracks and cracks will occur in the transfer layer, and it will not be possible to decorate the deep-drawn substrate (transfer target).

The present invention has been made in view of the above problems, and an object thereof is to prevent the transfer layer from being peeled off from the base sheet even when stretch-molded at room temperature, and Another object of the present invention is to provide a transfer sheet in which cracks, breaks, etc. are prevented from collapsing.

[0006]

In order to achieve the above object, the present invention provides a transfer sheet comprising a base material sheet and at least a decorative layer laminated on the base sheet. It is characterized in that the base sheet used is up to 150%, and the base sheet that follows the elongation of the decorative layer is used.

In the transfer sheet of the present invention, the transfer layer (the layer which is separated from the base material sheet and is transferred to the transferred material) is at least a decorative layer, but if necessary, a release layer and an adhesive layer may be provided. Is added. Therefore, as the layer structure of the transfer layer,
Base sheet / decorative layer, base sheet / release layer / decorative layer, base sheet / decorative layer / adhesive layer, or base sheet / release layer / decorative layer / adhesive layer.

In principle, the material for the substrate sheet may be any material as long as it has releasability from the transfer layer used in this type of transfer sheet, and its thickness is usually 5 to 200 μm.
m is preferable, and more preferably 19 to 50 μm. Specific examples of the material of the base sheet include polyethylene terephthalate, polybutylene terephthalate, polyester resins such as polyethylene terephthalate / isophthalate copolymer, polyethylene, polypropylene, polyolefin resins such as polymethylpentene,
Polyvinyl Fluoride, Polyvinylidene Fluoride, Poly Tetra Fluoro Ethylene, Poly Fluoro Ethylene Resins such as Ethylene Tetra Fluoro Ethylene Copolymer, Nylon-6, Nylon-6,6
Polyamide resin such as polyvinyl chloride, vinyl chloride, vinyl chloride / vinyl acetate copolymer, ethylene / vinyl alcohol copolymer, polyvinyl alcohol and other vinyl resins, cellulose triacetate, cellophane and other cellulose resins, polymethylmethacrylate Examples include acrylic resins such as polyethylmethacrylate and polybutylacrylate, and synthetic resins such as high-impact polystyrene, polycarbonate, polyarylate, and polyimide. It is not particularly limited as long as it is a material that can be stretched following it. The base sheet may be kneaded with a matting agent or the like, or may be printed or coated with a matting agent-containing ink that has releasability from the transfer layer and is in close contact with the base sheet. It is also possible to change.

On the release surface of the substrate sheet, a release layer, which is a surface layer of the transfer layer transferred to the substrate (transferred material), is formed as needed. That is, the release layer serves as a surface layer of the transfer layer that remains on the substrate (transfer target) side when the base sheet is released from the transfer sheet after the transfer step, and the transfer layer is used as the base sheet before transfer. It holds and facilitates peeling between the base sheet and the transfer layer after transfer, and further protects the transferred decorative layer. This release layer is
For example, acrylic resins such as polymethylmethacrylate and polybutylmethacrylate, polyurethane resins, vinyl chloride / vinyl acetate copolymer resins, unsaturated polyesters, chlorinated rubbers, cyclized rubbers and other resins, as well as mixed resins thereof, etc. The thickness is usually 1.0 to 4.0 μm, preferably 1.5 to 3.0 μm.

The decorative layer is to add design characteristics to the substrate (transferred material) by transferring the transfer layer, and is a pattern layer having a pattern, a pattern or the like, each layer alone or two layers thereof. It consists of the above. This decorative layer is formed by printing or applying an ink in which a colorant such as a dye or a pigment is added to a resin binder. In the present invention, the peeling of the transfer layer from the base sheet or the cracks or breaks of the transfer layer, which occur when the transfer sheet is three-dimensionally molded on the substrate (transfer target) at room temperature by the vacuum pressing method, constitutes the decorative layer. It was discovered that it depends on the stretchability of the resin (specifically, the elongation at break (%) is evaluated), and the transfer sheet of the present invention was developed.

The decorative layer is a layer that extends in accordance with the local stretching that occurs during vacuum forming at room temperature, and more specifically, at room temperature when the three-dimensional shape of an ordinary molded product is targeted. Any material having an elongation at break of 5 to 150% can be used. If the elongation at break is less than 5%, it can be transferred only to a substantially flat molded product. On the contrary, if it exceeds 150%, the foil burr becomes remarkable at the time of transfer and its removal becomes difficult. Here, the foil burr means that the transfer layer is not sharply cut at the boundary between the transferred part and the non-transferred part, and sticks out to form a so-called “burr”. The binder for this decorative layer has an elongation at break of 5 to 150.
% Or higher is selected. The resin that can be selected depends on the stretch ratio at the time of molding. Examples thereof include coalesce, vinylidene chloride / vinyl chloride copolymer, acrylonitrile / vinyl chloride copolymer, and rubber. Among these, a mixture of polyurethane and a vinyl chloride / vinyl acetate copolymer is preferable in terms of stretchability and foil burr prevention. The decorative layer uses these resins as vehicles, titanium white, carbon black, quinacridone, azo pigments, isoindolinone,
It is formed of a layer having a coloring or glittering property in which calcium carbonate, silica, barium sulfate, aluminum foil powder, titanium dioxide-coated mica foil powder or the like is dispersed. Then, the elongation at break of the decorative layer formed by adding the colorant or the like to the resin binder may be 5 to 150%. Foil burrs can be reduced by adding inorganic pigments such as calcium carbonate, silica and barium sulfate among the above pigments. However, if it is added too much, the elongation at break will decrease.

An adhesive layer is formed on the decorative layer as needed. This adhesive layer is, for example, an acrylic resin,
It is formed of a hot-melt resin such as an acrylic / styrene copolymer resin, a vinyl chloride / vinyl acetate copolymer resin, a thermoplastic polyurethane, an ionomer, a chlorinated rubber, a cyclized rubber, or a chlorinated polypropylene. It should be noted that when the adhesive layer is previously formed on the surface of the substrate that is the transfer target or when the decorative layer itself has heat-sensitive adhesiveness, it is not necessary to form the adhesive layer on the transfer sheet. Further, in the case where the surface of the substrate to be transferred is smooth, etc., the particle size is 0.5 to 5
A matting agent comprising silica, calcium carbonate, barium sulfate, kaolinite, talc, alumina, or other inorganic fine particles, or phenol resin, epoxy resin, melamine resin, or other thermosetting resin fine particles having a size of about μm, more preferably 1 to 3 μm Is added to form fine irregularities on the surface of the adhesive layer, the slip property between the transfer layer and the substrate before heat activation of the adhesive layer can be improved, and the fine irregularities on the surface of the adhesive layer can be prevented. It is possible to prevent air from being trapped between the transfer layer and the substrate during vacuum forming due to the favorable flow of the air sucked through the gap with the surface of the transfer body, and to prevent wrinkles from being formed during transfer. From this viewpoint, the fine irregularities on the surface of the adhesive layer, that is, the surface roughness, is preferably 0.4 μm or more in the center line average roughness (Ra) of JIS-B-0601.

If only fine irregularities are formed on the surface of the adhesive layer, the fine irregularities are embossed on the surface of the adhesive layer by a known method such as heat pressing without adding a matting agent to the adhesive layer. Good. However, in that case, the minute irregularities are likely to be reduced or disappeared depending on the temperature and pressure conditions during storage of the transfer sheet. Therefore, in order to avoid this, it is preferable to add a matting agent such as inorganic fine particles or thermosetting resin fine particles which are not easily deformed as described above.

The above resin layers in the transfer sheet can be formed by a coating means such as gravure coating or roll coating, or a printing means such as gravure printing or screen printing.

[0015]

The transfer sheet of the present invention is formed by coating the transfer target material at room temperature (about 10 to 30 ° C.) along the uneven shape by vacuum forming or vacuum pressure forming, and then pressing with a forming rubber. Transfer is performed according to a known vacuum press transfer method (see, for example, JP-A-5-131545, etc.) in which the transfer layer is heated to develop the adhesiveness and the transfer layer is adhered to the transfer target. That is, it is arranged so that the surface of the substrate that is the transfer target and the opposite surface (transfer layer side) of the base sheet of the transfer sheet face each other, and the transfer sheet is stretch-molded by vacuum molding at room temperature or the like to form the substrate After the alignment, the base material sheet side is pressed by the molding rubber and is heated by the heat of the molding rubber, so that the three-dimensional surface of the substrate having the three-dimensional shape is favorably decorated. In this case, since the transfer layer is molded on the surface of the substrate in a state where the adhesive force has not yet been expressed (activated) at room temperature, even if wrinkles, lumps, air pockets, etc. are present at the moment of bonding to the substrate surface. The transfer sheet slips on the surface of the substrate and moves to remove them, and cracks and breaks due to elongation of the transfer layer do not occur.

Embodiments of the present invention will be described below with reference to the drawings.

[0017]

【Example】

(Example) A transfer sheet S having a laminated structure shown in FIG. 1 was produced by the following procedure. First, thickness 2 with corona treatment on one side
A 6 μm matte polyester film (Lumirror X455, manufactured by Toray) was used as the base sheet 1, and a mat ink layer 2 that remained on the base sheet side after transfer was formed on the corona-treated side of the base sheet 1. . Specifically, a mixture of a matte ink consisting of aminoalkyd / butylated melamine / silica powder (weight ratio: 70/15/5) and a hydrochloric acid (20%) methanol solution at a ratio of 100: 5 was gravure-printed. After printing with a desired pattern, heat treatment was performed at 100 ° C. for 5 seconds.

Next, a peeling varnish (acrylic resin, glass transition point: 105 ° C.) is applied over the entire surface of the matte ink layer 2 to form a peeling layer 3 having a thickness of 2.5 μm. A decorative layer 4 was formed on top of No. 3. Specifically, the colored pattern layer 4a is formed in a desired pattern with a flexible ink whose binder is polyurethane / vinyl chloride / vinyl acetate copolymer (weight ratio: 50/50), and the colored pattern layer 4a is formed thereon. Solid layer 4 with different hue
b was formed with the same kind of flexible ink to a thickness of 2.5 μm, and further solid layers 4c and 4d having a thickness of 3 μm were formed with the same kind of white flexible ink.

Then, an adhesive layer 5 was formed on the decorative layer 4. Specifically, a mixture of silica powder having a particle diameter of 2.5 μm at a ratio of 5% by weight as a matting agent to an acrylic resin binder was applied to a thickness of 4 μm. The surface roughness of this adhesive layer 5 is JIS-B-0601.
The center line average roughness was 0.45 μm.

Using the transfer sheet S thus prepared, an air-conditioning panel with a three-dimensional curved surface lattice formed of polystyrene resin (the transfer sheet has a maximum elongation of 5% in the portion covered by the transfer sheet). Designed in shape)
On the other hand, it was decorated by the vacuum press transfer method. As a procedure, first, the adhesive layer 5 of the transfer sheet S was arranged so as to face the panel surface, and the transfer sheet S was stretched and formed by vacuum forming at room temperature of 20 ° C., and was placed along the air conditioner panel. In this state, a silicone molding rubber heated to 170 ° C. was pressed from the side of the base material sheet 1 for about 3 seconds to heat and pressurize, and then the base material sheet 1 was peeled off.

As a result, the air-conditioning panel including the three-dimensional curved surface was well decorated without cracks or cracks in the transfer layer. Furthermore, what was called a foil burr did not occur in the lattice part of the air conditioner panel. In addition, the decorative surface had a high-grade decoration with a gloss matte effect.

(Experiment 1) A transfer sheet having the same layer constitution was prepared by changing the resin blending ratio in the binder of the flexible ink forming the decorative layer 4 in the above-mentioned embodiment, and using this, an air conditioner panel was used in the same manner as in the above-mentioned embodiment. Decorated. The film thickness of the decorative layer 4 is the same as that in the above-mentioned embodiment. The results of evaluation in each of these cases are shown in Table 1 together with the above examples (indicated in C). In Table 1, X is polyurethane and Y is vinyl chloride.
Represents a vinyl acetate copolymer.

[0023]

[Table 1]

As can be seen from these results, when the elongation at break is 5 to 150%, the decorative layer is not cracked, and the transfer failure does not occur due to delamination of the transfer layer during transfer. It was Further, foil burr was not generated, or even if it was generated in a small amount, it could be easily removed by cloth wiping or air blowing.

(Experiment 2) Adhesive layer 5 in the above embodiment
By changing the mixing ratio of the matting agent (silica powder having a particle size of 2.5 μm) in the inside, a transfer sheet having the same layer structure (the adhesive layer has the same thickness of 4 μm) is prepared, and the air conditioner panel is similarly decorated. did. The results of evaluation in each of these cases are shown in Table 2 together with the examples (shown in H).

[0026]

[Table 2]

As can be seen from these results, the surface roughness of the adhesive layer is the center line average roughness (R) of JIS-B-0601.
In the case of a) having an adhesive layer of 0.4 μm or more, no air pockets and the like were generated when transferred to any substrate (transfer target). There is no particular upper limit to Ra from the viewpoint of air accumulation, but if it is too large, the surface of the transfer layer will become rough, so an appropriate Ra may be selected within such a range. The particle size of the matting agent to be added is preferably in the range of 1 to 3 μm. If it is less than 1 μm, Ra of 0.4 μm or more cannot be produced at all, or even if it is produced, the amount of addition becomes too large and the coating becomes brittle or loses printability, and conversely exceeds 3 μm. Then, even if Ra is the same, Rmax (JIS-B-0
This is because the maximum height (601) tends to increase, and the surface of the transferred transfer layer becomes rough.

[0028]

Since the present invention is constructed as described above, it has the following effects.

After the transfer sheet is vacuum formed at room temperature, the transfer layer is heated to develop the adhesiveness of the transfer layer and transferred, whereby the three-dimensional molded article can be decorated with a curved surface. At that time, wrinkles, lumps, and air traps on the transfer sheet, which tend to occur, are not generated. In addition, cracks and the like due to elongation of the transfer layer do not occur.

It is not necessary to heat the transfer sheet as a pre-transfer operation, and a curved surface can be efficiently decorated on a three-dimensional molded product by an inexpensive transfer system utilizing a conventional vacuum press transfer machine.

It becomes possible to decorate a molded three-dimensional molded product with a curved surface, and it is possible to modify the decorating, which was not possible with the existing three-dimensional transfer system (in-mold molding method), and it is possible to improve the yield. it can.

[Brief description of drawings]

FIG. 1 is a sectional view of a transfer sheet for explaining an embodiment of the present invention.

[Explanation of symbols]

 1 Base Material Sheet 2 Matte Ink Layer 3 Release Layer 4 Decorative Layer 4a Pattern Layer 4b, 4c, 4d Solid Layer 5 Adhesive Layer

Claims (1)

[Claims] 1. A transfer sheet comprising at least a decorative layer laminated on a base sheet, wherein the decorative layer has an elongation at break of 5 to 150% at room temperature, and the base sheet is a decorative layer. A transfer sheet that uses a material that follows elongation.