JPS58132529A - Simultaneous injection and molding process - Google Patents

Abstract

PURPOSE:To do the surface treatment of a molded article simultaneously with an injection molding and intend the automatization, the mass production and the energy saving of a manufacturing process, by heat-molding a face transfer sheet in the one side of a mold, then injection-molding closing the mold with another side of the mold. CONSTITUTION:A face transfer sheet A composed of for example a carrier film 1, a separating layer 2, ink layers 3, 4 and a hot melt type adhesive layer 5, being heated by a heater 11, is vacuum-molded in a mold 10 provided with a vacuum hole 10a and a connecting hole 10b connected to a vacuum pump. A molded article of which the surface is treated with the transfer of the layers 2- 5 of the transfer sheet is obtained by moving the heater 11, facing the mold 10 to another mold 9 by moving the mold 10, then doing an injection molding. EFFECT:The cost down of a product is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION In general, resin molded products used in industrial products are put into practical use after being subjected to various surface treatments after injection molding. As this surface treatment method, painting, plating, transfer (hot stamping), silk printing, etc. are often used. However, from the viewpoint of social demands for resource and energy conservation, the current situation is that the above-mentioned surface treatments are all post-processing and cannot effectively utilize thermal energy, pressure energy, etc. during injection molding. For this reason, if surface treatment can be performed at the same time as conventional injection molding, it will be possible to meet the above social demands and automate the process.

Various studies have been conducted because unmanned operation is possible and a significant cost reduction can be achieved. In particular, if the resin molded product is a small molded product with a depth of 10 to 15 mm or less, a transfer sheet, leather sheet, etc. is sandwiched onto the parting surface of the mold, and then injection molded, eliminating the need for post-processing. The following method is used. However, in the case of large molded products and deep drawn molded products, the sandwiched sheet may be torn or wrinkled, resulting in a high number of defective products, and therefore cannot be put to practical use. As a result of intensive research, the inventors of the present invention have found a new method in which the decorative transfer sheet is thermoformed on one side of the mold, and then the mold is closed on the other side of the mold to perform injection molding. did it.

Conventionally, in the case of large molded products, a method of vacuum forming a decorative thermoplastic resin sheet, inserting it into a mold, and injection molding has also been put into practical use. In this case, heat-resistant ABS resin sheets are commonly used as decorative thermoplastic resin notebooks because the sheet must not be torn by the heat and pressure during injection molding. However, a drawback of this method is that it requires a vacuum molding mold in addition to the injection molding mold.

Furthermore, since the thermoplastic resin sheet after vacuum forming is inserted into a mold, it has the drawback of being difficult to automate and resulting in high costs. Furthermore, it is necessary to trim the unnecessary sheets at the ends of the molded product.

As a method different from the above conventional method, there is a method in which the decorative transfer sheet is matured on one side of the mold, and then the mold is closed on the other side of the mold and injection molding is performed, which does not require post-processing and is automated. We came to the conclusion that this method is possible and suitable for commercial products.

The method of the present invention will be described in detail below. First, the decorative transfer sheet has a material structure shown in FIG. In the figure, 1 is a carrier film. This film 1 needs to be suitable for thermoforming such as vacuum forming, and needs to be transparent, so it can be made of vinyl chloride, unstretched polyenalene terephthalate polysterene resin, AB
Thermoplastic resin such as S resin is used. 2 is a release layer, 3.4 is an ink layer having a wood grain pattern, etc., and 6 is a hot melt type adhesive layer. In particular, as the adhesive, an acrylic resin adhesive having a melting point of 100° C. to 150° C. is preferable.

Next, the steps of this method will be explained with reference to FIG.

Reference numeral 6 denotes a supply roll for the decorative transfer sheet, which supplies the decorative transfer sheet via a pinch roller 7 and finally winds it up on a take-up roll 8 . Also, 9 is a mold, 10 is a mold, and 10 a is a mold 1.
0 is a vacuum hole for vacuum forming, 10b is a connection hole for a vacuum pump provided in the mold 1o, and 11 is a sheet heater.

Here, the decorative transfer sheet A shown in FIG.
Vacuum forming through 0b. After that, the heater 11'f
:” After moving in two directions and positioning it outside the mold 1o,
The mold 10 is moved and butted against the mold 9 on the other side.

Then, injection molding is performed, molds 9 and 10 are opened, and mold 1
Take out the molded product from inside 0. At this time, the surface of the molded product is peeled off between the gear rear film 1 and the release layer 20 in FIG. 1 due to the decorative transfer sheet A), and layers 2 to 5 are transferred to the surface of the molded product. That is, the adhesive 5 becomes molten due to the heat and pressure during injection molding, and after injection molding,
It is cooled and bonded.

Note that the heater 11 is a rod-shaped or plate-shaped heater,
A far-infrared type is suitable. After the above-mentioned process is completed, the molded product is completely destroyed, and the unnecessary sheet portion after the transfer is wound up on the take-up roll 8, and at the same time, a new decorative transfer sheet A is supplied from the supply roll 6.

Therefore, a major feature of this method is that the mold 10 serves both as an injection mold and a vacuum mold. That is, a large number of vacuum holes 10a and 10f are provided, and a connection hole 10bi connected to a vacuum pump is provided to complete vacuum forming in the mold 1o before injection molding. In this case, if the vacuum forming is not sufficient, the decorative transfer cant may be torn or wrinkled due to the heat and pressure during injection molding, and the resulting molded product will have a poor appearance and become unusable. For this reason, it is extremely important to perform vacuum forming so that the mold 10 is brought into close contact with the inside of the mold 10. The case in FIG. 2 is for a direct gate molded product, but in the case of a tunnel gate, the mold cavity surface serves both as an injection mold and a vacuum mold.

Note that FIG. 2 is a longitudinal cross-sectional view of the mold, and is a view of the injection molding from the lateral direction.

As described above, according to the method of the present invention, it is possible to obtain a molded product that is sufficiently durable for practical use by surface treatment at the same time as injection molding, and is therefore energy-saving, and its value is extremely high. .

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of the material structure of a decorative transfer sheet, and FIG. 2 is a longitudinal sectional view showing an example of the structure of an apparatus for realizing the simultaneous injection molding method of the present invention. A... Decorative transfer sheet, 6..., Decorative transfer shift supply 07/l/, 8... Winding roll, 9.10... Mold, 10a...Vacuum hole, 10b...Connection hole, 11...Heater.

Claims (1)

[Claims] A simultaneous injection molding method in which a decorative transfer sheet is thermoformed on one side of the mold, and then the mold is closed on the other side of the mold to perform all injection molding and surface treatment at the same time.