JPH0558098A - Transfer foil for decoration simultaneous with injection molding - Google Patents

Abstract

PURPOSE:To enable transfer simultaneous with in-mold formation even for a molded item having relatively severe shape by making impact strength and elongation at rupture of biaxially stretched polyester film as a base film in both flow direction and width direction larger than specific values. CONSTITUTION:A transfer leaf has a conventional constitution, excluding base film material and its physical properties and, as a strippable base film, a biaxially stretched polyester film having a thickness of 25-100mum, impact strength at film formation of 80kgf mm or more and elongation at rupture in both flow direction and width direction of 120% or more is employed. If necessary, coating of mold releasing resin such as a mixed resin of silicone, melamine and acryl, fluororesin etc., a mold release layer formed from extrusion coat, a strippable layer having a thickness of about 0.1-10mum made of thermosetting resin or ionizing radiation setting resin etc., are layered successively over the base film, on which an appropriate pattern layer is printed by means of gravure printing, gravure-offset printing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer foil for painting, and in particular, during injection molding, a transfer foil for makeup inserted between male and female molds is integrated with an injection resin to form a paint on the surface against molding. The present invention relates to a transfer foil for painting used when performing.

[0002]

2. Description of the Related Art Conventionally, as a method of forming characters and patterns on a synthetic resin molded product, there is a method of directly painting on the surface after molding by a method such as transfer, but for molded products having complicated shapes Are either impossible or extremely difficult to implement. Therefore, it is common to perform painting directly on a molded product with a complicated shape by pad printing, painting, etc. However, since molding and painting are separate processes, that is, two processes, cost is reduced. There is a demand for an improved method for painting an injection-molded article having a severe shape, which is disadvantageous both in terms of time and time.

An injection molding simultaneous painting method is known as one of the means. The injection molding simultaneous painting method means that, during injection molding, the transfer foil is inserted between the male and female molds so that the transfer layer faces the cavity side, and after the mold is clamped, the resin is injected to separate the injection resin and the transfer foil. A method of painting a synthetic resin molded product by creating a united molded product, cooling and demolding it, peeling only the base film of the transfer foil, and leaving the transfer layer on the surface of the molded product. , Which is roughly classified as an in-mold molding simultaneous transfer method, after the mold is clamped, the transfer foil is made to conform to the mold shape by heat and pressure of the injection resin and the injection resin and the transfer foil are united. A method of forming a molded body (see Japanese Patent Publication No. 2-4080), a transfer foil is fixed to a female mold for injection molding so that a printing layer is on a side opposite to the female mold, and the transfer foil is heated and softened. After performing pre-forming by vacuum suction into the female mold, place the male mold on the female mold. Body allowed,
A method is known in which a molten synthetic resin is injected into a male and female mold to form a molded body in which the injected resin and a transfer foil are united (see Japanese Patent Publication No. 50-19132).

This molding method is effective because it is possible to perform in-line molding and painting only within the injection molding apparatus even for a molded product having a considerably strict shape as long as the shape pattern can be vacuum-molded. Has become a means.

[0005]

The injection molding simultaneous painting method described above, however, has some problems to be solved. That is, in the in-mold molding simultaneous transfer method, the transfer foil is heated and softened by the heat and pressure of the injection resin and pressed onto the inner surface of the female mold at the same time as molding, so that the transfer foil itself has a considerable moldability. Therefore, as a material for the base film, vinyl chloride film,
Resin sheets such as unstretched or uniaxially stretched polyethylene terephthalate film are mainly used.
This means that the transfer foil is poor in dimensional stability and is accompanied by defects due to misalignment during printing and misalignment during molding.
Inevitably, there is a limit to the painting that can be performed.

In the simultaneous forming and painting method for performing preforming, since the transfer foil is heat-formed in advance and brought into close contact with the inside of the female mold, there is no particular limitation on the material of the base film of the transfer foil. All that can withstand the thermal environment during injection molding can be used, and sufficient transfer can be performed even for molded products with severe shapes. Compared with this, the time for preforming is required, or the equipment for preforming needs to be attached to the injection molding apparatus, which leads to high product cost.

[0007] In order to obtain a transfer foil free from printing defects and misalignment, a base film is made of a polyester resin sheet.
It is empirically known that it is preferable to use a biaxially stretched polyester film, but polyester resin sheets that are generally manufactured lack moldability,
As it is, it lacks adaptability as a base film for transfer molding used in the in-mold molding simultaneous transfer method.

That is, PET (polyethylene terephthalate), which is one of ordinary biaxially stretched polyester films, is used.
G) The film has a breaking strength of 100 to 150%, but an impact strength of 40 to 80 kgf · mm, and is pressed to the molding surface with a momentary stress such as injection resin pressure in injection molding. If you do, damage will occur depending on the shape. For example, it is extremely difficult to form a shape obtained by half-cutting a columnar surface (a cylinder, an elliptic cylinder, a hyperboloidal column, etc.) having an edge with a radius of curvature of about 5 mm, that is, a so-called kamaboko shape. In addition, when referring to "impact strength" in the present specification, in the impact test by ASTM-D-3763, a 1/2 inch R attachment is used as an attachment at 3.3 m / sec at 23 ° C. The value of. The unit of measurement is "load x elongation at break", for example, kgf · mm. By increasing the thickness, it is possible to increase the apparent impact strength, but if the thickness increases, it will not strictly follow the uneven shape of the molding surface instead of causing damage,
As a base film for a transfer foil, an upper limit naturally occurs for a base film for a transfer foil due to a molded product having a strict surface shape, and it is empirically that the value is about 50 μm or less for practical use.

In order to solve the above-mentioned inconveniences of the prior art, the inventors of the present invention have evaluated the impact strength and elongation at break of the base film of the transfer foil used in the in-mold molding simultaneous transfer method, and the values at the time of molding. Even after using a biaxially stretched polyester film as the base film, we have conducted extensive research on damage to control the impact strength and elongation at break by adjusting the film-forming conditions, etc. The present invention has been completed by finding that in-mold molding simultaneous transfer can be performed even for a severe molded body.

[0010]

As a means for solving the above problems, the present invention provides a transfer foil for simultaneous injection-molding, which comprises a biaxially stretched polyester film and at least a picture layer laminated thereon, Disclosed is a transfer foil for simultaneous injection-molding painting, characterized in that the biaxially stretched polyester film as a base film has an impact strength of 80 kgf · mm or more and a breaking elongation rate of 120% or more in both the machine direction and the width direction. .. It is a particularly preferred embodiment that the biaxially stretched polyester film is a polyethylene terephthalate film.

As the constitution of the transfer foil according to the present invention, the constitution of the conventional transfer foil for simultaneous injection-molding painting can be used as it is except for the material of the base film and the physical properties thereof. That is, the peelable base film has a thickness of 25 to
A biaxially stretched polyester film having a thickness of 100 μm and an impact strength of 80 kgf · mm or more and a breaking elongation of 120% or more in both the flow direction and the width direction at the time of film formation by the means described later is used. A silicone resin, a mixed resin of melamine and acrylic, a release resin such as a fluororesin, or a release layer formed by an extrusion coat, a thermosetting resin or an ionizing radiation curing resin. A peeling layer having a thickness of about 1 to 10 μm is sequentially laminated. An appropriate pattern layer is printed thereon by means such as gravure printing and gravure offset printing.

If necessary, an adhesive layer made of a heat-sensitive adhesive or the like is formed on the pattern layer to transfer and adhere the transfer layer to the transferred material. This adhesive layer can be omitted if the transfer layer itself such as a pattern layer and a release layer has sufficient adhesiveness. Furthermore, in order to improve the adhesiveness between the injection resin and the release foil, the surface may be subjected to an easy adhesion treatment such as corona discharge treatment or various known primer coatings. Further, a surface protective layer may be provided to improve surface properties such as scratch resistance and stain resistance of the decorative decorative layer, and an antistatic layer may be formed on the back surface of the peelable base film, if necessary. You can also do it.

In the present invention, when a biaxially stretched polyester film which is a peelable base film is formed, the film forming conditions are changed to increase the impact strength. As a method therefor, the draw ratio and the heat setting temperature are increased. As a result, the impact strength of a normal biaxially stretched polyester film is 40 kgf · mm, while that after adjustment is 8
It was possible to obtain items of 0 kgf · mm or more.

Using the biaxially stretched polyester film thus prepared as a peelable base film, a peeling foil is formed by a conventional method. When the simultaneous injection-molding painting was performed using the peeling foil by the same method as the conventional method, the peeling foil can be applied even to the resin molded product having a severe surface shape which was impossible in the past. No breakage occurred, and painting and peeling of the peeling film were carried out satisfactorily.

[0015]

EXAMPLES The present invention will be described below with reference to examples.

[0016]

Example 1 A biaxially stretched PET (GH38; thickness: 38 μm, manufactured by Tia foil Co., Ltd.) coated with an acrylic / melamine release layer was prepared at a higher stretching ratio and heat setting temperature than usual film forming conditions during PET film formation. And the impact strength is 85
kgf · mm and elongation at break were set to 130%. On the release surface of the film, a release layer, a pattern layer, and an adhesive layer are sequentially printed with gravure ink to produce a release foil, and both ends have a kamaboko-shaped protrusion with a curvature of 5 mm, a width of 6 mm, and a height of 3 mm. Injection molding simultaneous painting was performed on the molded product. ABS resin was used as the resin. After cooling and demolding, the release base film was peeled off, leaving only the transfer layer on the surface of the molded product.

No breakage occurred in the release foil.

[0018]

[Example 2] A biaxially stretched PET (GH50; thickness 50 µm, manufactured by Tia foil Co., Ltd.) coated with an acrylic / melamine release layer was subjected to stretching ratio and heat setting temperature as in Example 1 at the time of PET film formation. Prepared and impact strength 9
The breaking elongation was set to 8.5 kgf · mm and 120%. A transfer foil was produced using the film in the same manner as in Example 1, and then a molded product was molded.

No breakage occurred in the release foil.

[0020]

Example 3 A biaxially stretched PET having an impact strength of 90.0 kgf · mm and an elongation at break of 125% was prepared by adjusting the stretching ratio and heat setting temperature as in Example 1, and acryl-melamine was formed on the film. Resin coating (170 ℃ × 30
Then, the release-treated surface was subjected to the same treatment as in Example 1 to produce a transfer foil, and then a molded product was molded.

No breakage occurred in the release foil.

[0022]

[Comparative Example 1] Biaxially stretched PE with impact strength of 60.0 kgf · mm
T was prepared at a normal heat setting temperature, and the release treated surface was subjected to the same treatment as in Example 1 to produce a transfer foil, and then a molded product was molded. The breakage rate of the release foil was 100%.

[0023]

EFFECTS OF THE INVENTION Even for a molded product having a severe surface shape, simultaneous injection molding and painting can be carried out without causing breakage of the transfer foil.

Claims (1)

[Claims] 1. A transfer foil for injection-molding simultaneous painting, comprising a biaxially stretched polyester film and at least a pattern layer laminated on the biaxially stretched polyester film, which is measured by ASTM-D-3763 of a biaxially stretched polyester film as a base film. A transfer foil for simultaneous injection-molding painting, which has an impact strength of 80 kgf · mm or more and a breaking elongation of 120% or more in both the flow direction and the width direction.