JPH045358Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention is made by inserting into the mold after being molded in advance,
The present invention relates to a transfer sheet suitable for adding a pattern to molding resin injected into a mold.

Various materials have been tried as base materials for transfer sheets for applying patterns during injection molding, but the reality is that nothing satisfactory has yet been obtained.
Typical examples of transfer sheet substrates that have been attempted in the past include nylon film, polyethylene terephthalate film (stretched), stretched polypropylene film,
It is polyvinyl chloride film. However, although nylon film has excellent moldability and heat resistance, it has the disadvantage of being easily stretched during long printing, while polyethylene terephthalate film (stretched) is difficult to stretch during long printing, that is, it has excellent dimensional stability, but Moldability is insufficient. Although stretched polypropylene film can be molded, the temperature range in which it can be molded is narrow, and the resulting molded sheet has a lot of uneven thickness, and the film does not have sufficient heat resistance.Furthermore, a hard polyvinyl chloride film is selected. This provides dimensional stability and excellent moldability, but on the other hand, it has poor heat resistance.

Generally, the base material of the transfer sheet used for patterning during injection molding has dimensional stability, moldability (for example, moldability that can be vacuum formed by heating to about 100°C), and injection moldability. Heat resistance must be sufficient to withstand the temperature of the injected resin that comes into contact with it during molding, but no material with all of these properties has been available.

The inventors of the present invention have conducted various studies in an attempt to eliminate the drawbacks of the prior art as described above, and have developed a synthetic resin film layer that has dimensional stability and moldability, and a synthetic resin that has heat resistance and vacuum moldability. The inventors have discovered that all the drawbacks of the prior art can be overcome by laminating film layers to form the base material of the transfer sheet, and have thus arrived at the present invention.

That is, the present invention provides a method for forming a layer on a second synthetic resin film layer on a laminate including a first synthetic resin film layer having dimensional stability and moldability, and a second synthetic resin film layer having heat resistance and moldability. A printed pattern layer is laminated on the laminate, and the laminate has dimensional stability with virtually no elongation against tension loads associated with processing such as printing in a temperature range from room temperature to 70°C. , has moldability to the extent that it can be vacuum formed at a temperature of 100℃ or higher, has heat resistance that does not cause thermal deformation or blistering even when it comes into contact with molten resin injected by injection molding, and has a total thickness of 50 to 200 μm. Well, the second one
The thickness of the synthetic resin film layer is 20 to 50% of the total thickness.
It is characterized by:

Furthermore, in the transfer sheet, an adhesive layer can be laminated on the printed pattern layer, or a release layer can be laminated between the second synthetic resin film layer and the printed pattern layer on the laminate, if necessary. .

To explain the transfer sheet of the present invention in more detail with reference to the drawings, as shown in Fig. 1, the transfer sheet A, which is the most preferred embodiment of the present invention, is a first synthetic resin film having dimensional stability and moldability. layer 1
and a second synthetic resin film layer 2 having heat resistance and vacuum formability are laminated together with an adhesive layer 3 interposed therebetween,
A peelable layer 5 is further formed on the synthetic resin film layer 2 side of the laminate 4 made up of the above layers, and a printed pattern layer 6 and an adhesive layer 7 are sequentially formed on the surface of the peelable layer 5. This is what is being done.

Each layer 1 to 6 in the above will be explained next.

The first synthetic resin film layer 1 supports the second synthetic resin film layer 2 and reinforces the laminate 4, and is necessary for printing on the laminate 4 (via a peelable layer if necessary). In addition to providing excellent dimensional stability,
It is necessary that the moldability is equivalent to that of the synthetic resin film layer 2 or that it does not substantially deteriorate during lamination. Specific materials for the first synthetic resin film layer 1 include polyvinyl chloride resin films (especially hard ones with a non-plastic to 5 PHR), acrylic resin films such as polymethyl methacrylate resin films, unstretched polyethylene terephthalate resin films, Alternatively, an unstretched polypropylene resin film may be used.

The second synthetic resin film layer 2 has moldability,
It is necessary to have heat resistance to the extent that deformation or blistering does not occur due to the heat of the molten resin injected during injection molding. Second synthetic resin film layer 2
The specific material is 6-nylon or 6,
6-Polyamide resin film such as nylon, acrylic resin film such as polymethyl methacrylate, acrylonitrile resin film, polyarylate resin film, polycarbonate resin film, cellulose resin film such as cellulose diacetate, cellulose triacetate or cellulose acetate butyrate, etc. can be mentioned.

The adhesive layer 3 laminates both the first synthetic resin film layer 1 and the second synthetic resin film layer 2, and prevents peeling or shifting during molding of the transfer sheet or injection molding. It is necessary that the material can be stretched in the same way as the first and second synthetic resin film layers during molding of the transfer sheet. Specific materials for the adhesive layer 3 include polyvinyl acetate resin, polyvinyl alcohol resin, polyvinyl acetal resin, polyvinyl chloride resin, acrylic resin such as polyacrylic acid ester resin, polyethylene resin, or cellulose resin. Examples of adhesives include thermoplastic resin adhesives such as those based on nitrile rubber, styrene rubber, or elastomer adhesives such as butyl rubber.

To manufacture the laminate 4, after applying an adhesive to one or both of the adhesive surfaces of each synthetic resin film constituting the first and second synthetic resin film layers,
This may be carried out by lamination such as dry lamination, or by melting and extruding an adhesive and pressing each synthetic resin film from both sides.

The laminate 4 has temperature stability for dimensional stability during printing.
The elongation must be 0.1% or less in an atmosphere of 70°C or lower, and it must also be moldable at temperatures of 100°C or higher, and heat resistant without blistering or thermal deformation at the temperature of the molten resin during injection molding. sexuality is required.

The reason for this is that in the intended application of the present invention, when printing on the base material of the transfer sheet, the ink is usually placed in an atmosphere with a maximum drying temperature of about 70°C, but the registration of multicolor printing due to film expansion and contraction is If it is less than 0.1 mm, it is practically unnoticeable, and is usually used in preliminary forming such as vacuum forming prior to injection molding.
Formed into a mold shape at a temperature of 100℃ or higher,
During injection molding transfer, the surface of the base sheet is usually kept at a temperature of 100℃ or higher due to the injection molding resin.
This is because if the base film is deformed or blistered at this time, the pattern on the molded product may be distorted or wrinkled.

From the above point of view, the thickness of the laminate 4 is 50 to 200 μm,
Preferably it is 50 to 100 μm. The thickness of the second synthetic resin film layer of the laminate 4 is 20 to 50%, preferably 30 to 50%, of the thickness of the laminate 4. If the thickness of the laminate 4 is less than the lower limit, it will be difficult to handle, and if it exceeds the upper limit, the thickness will likely be uneven when molded into a molded sheet. In addition, if the thickness of the second synthetic resin film layer is less than the lower limit, wrinkles will easily appear when formed into a molded sheet, and if it exceeds the upper limit, moldability tends to decrease, and in general, resin films with high heat resistance are Since it is expensive, the cost will increase.

The peelable layer 5 imparts peelability to the surface of the layer 2 side of the laminate 4, and is made of, for example, acrylic resin such as polymethacrylate resin, polyvinyl chloride resin, polyvinylidene chloride resin, acrylonitrile resin, etc. Among thermoplastic resins such as styrene copolymer resin, polystyrene resin, or acrylonitrile-butadiene-styrene copolymer resin, or chlorinated rubber, these resins have excellent releasability during heat transfer. A material with low releasability is appropriately selected and used while taking into consideration adhesiveness with the printed pattern layer described later.

The printed pattern layer 6 is formed using ordinary inks and printing methods, and the ink vehicle may be, for example, chlorinated polypropylene resin, ethylene-vinyl acetate resin, vinyl chloride-vinyl acetate copolymer resin, or polyester. It is appropriately selected from acrylic resins such as (meth)acrylic acid ester resins.

The adhesive layer 7 increases the adhesion between the resin injected during transfer and the printed pattern layer 6 of the transfer sheet A, and the specific materials are those constituting the adhesive layer 3 in the laminate 4. Similar things can be mentioned.

Although the most preferred example of the present invention has been described above, one or some of the layers may be omitted in the transfer sheet A of FIG. 1, as described below.

(B) First, the adhesive layer 3, which is the intermediate layer of the laminate 4, can be laminated by the first and second synthetic resin film layers without the need for an adhesive layer by heat fusion, high frequency adhesion, etc. of each layer. You can omit this at times.

(b) Next, the releasable layer 5 can be omitted when the space between the second synthetic resin film layer and the printed pattern layer 6 has releasability due to the selection of the respective materials. In short, it is sufficient that the surface of the laminate 4 on the printed pattern 6 side has releasability during thermal transfer.

(c) Furthermore, the adhesive layer 7 is attached to the printed pattern layer 6 during heat transfer.
This is to bond the injected molding resin and the printed pattern layer to the surface of the molded body, but since the adhesive layer 7 acts like a heat-sensitive adhesive, it can also be affected by the vehicle in the printed pattern. Alternatively, the printed pattern layer can also be used as an adhesive layer by replacing part or the front part of the vehicle with the material constituting the adhesive layer 7. In such a case, the adhesive layer 7 can be omitted.

According to the present invention, as the base material of the transfer sheet, the first synthetic resin film layer having dimensional stability and moldability is placed on the side opposite to the printed pattern, and the first synthetic resin film layer having heat resistance and moldability is placed on the printed pattern side. This is a laminate obtained by laminating second synthetic resin film layers each having a has dimensional stability with virtually no elongation,
Formability to the extent that vacuum forming is possible at temperatures of 100℃ or higher,
It also has heat resistance without thermal deformation or blistering even when it comes into contact with the molten resin injected by injection molding, and has a total thickness of 50 to 200 μm, of which the thickness of the second synthetic resin film layer is the total thickness. By adopting a configuration that is 20 to 50% of It has excellent formability in vacuum forming and the like, and even when injection molding is performed using a molded transfer sheet, it is possible to form a pattern on the surface of the molded product due to the heat of the casting resin without causing problems such as pattern distortion or wrinkles.

In addition, the transfer sheet of the present invention has excellent dimensional stability, so conventionally, after hot stamping, characters, symbols, patterns, etc. that require dimensional and positional accuracy can be printed directly onto the molded product using a silk screen. However, by aligning and performing all the necessary printing on one transfer sheet, it is possible to perform transfer in one go.

Example A polyamide resin adhesive was gravure coated on one side of a 100 μm thick polyvinyl chloride resin film (hard), and a 40 μm thick 6-nylon film was dry laminated on the coated surface. A releasable layer, a printed pattern layer, and an adhesive layer were formed on the 6-nylon film side of the obtained composite film using each composition using a polymethyl methacrylate resin as a vehicle to prepare a transfer sheet.

The obtained transfer sheet is formed by vacuum forming,
A molded article with a pattern was obtained by placing the molded sheet in a mold and performing injection molding.

In the above, there was no misregistration of printing on the transfer sheet, and no defects during vacuum molding or injection molding.

For comparison, the same procedure as above was carried out except that a 140 μm thick polyvinyl chloride resin film alone and a 140 μm thick 6-nylon film were used. When the polyvinyl chloride resin film was used, printing misregistration and There were no defects during vacuum forming, but holes were formed in the transfer sheet base material during injection molding, resulting in areas with no pattern on the molded product, and when using 6-nylon film, vacuum forming and injection molding Although the printing process itself was successful, due to misregistration of the printing on the transfer sheet, the pattern applied to the molded body had a color shift.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of the transfer sheet of the present invention. 1...First synthetic resin film layer, 2...Second
synthetic resin film layer, 3...adhesive layer, 4...
Laminate, 5...Peelable layer, 6...Printed pattern layer, 7
...Adhesive layer.

Claims (1)

[Claims for Utility Model Registration] (1) A first synthetic resin film layer that has dimensional stability and moldability, and a second synthetic resin film layer that has heat resistance and moldability.
A second layer on a laminate consisting of a synthetic resin film layer of
A printed pattern layer is laminated on a synthetic resin film layer, and the laminate does not substantially elongate under tension loads associated with processing such as printing in a temperature range from room temperature to 70°C. It has dimensional stability, has moldability to the extent that it can be vacuum formed at temperatures of 100℃ or higher, has heat resistance that does not cause thermal deformation or blistering even when it comes into contact with molten resin injected in injection molding, and has a total thickness of is 50 to 200 μm, and the thickness of the second synthetic resin film layer is 20 to 50% of the total thickness. (2) The transfer sheet according to item (1) of the utility model registration claim, further comprising an adhesive layer laminated on the printed pattern layer. (3) Paragraph (1) of the claims for utility model registration, characterized in that a release layer is further laminated between the second synthetic resin film layer and the printed pattern layer on the laminate; or The transfer sheet described in paragraph (2).