JPS58131039A - Printing method of injection molded article - Google Patents

Abstract

PURPOSE:To do an injection molding and a transfer printing at the same time and shorten a process, by holding an extensible film on which a pattern is printed at the outer periphery of the injection molding position of a mold and pressure-feeding a raw molding material between the film and the mold. CONSTITUTION:A film 3 of which a printed pattern is faced to a core 2 is seated at the molding part of the female mold of a cavity 1 via a feed pitch 4 and the film 3 is fixed to the outer periphery of the molding part of the female mold with a fixing ring 5 by advancing a rod 6. When a raw resin material 7 is supplied at a molding pressure between the film 3 in the mold and the core 2, the film 3 is stretched and attached to the molding part of the female mold of a cavity 1 by the molding pressure, the printed pattern is adhered to the raw resin material 7, the raw molded material 7 is molded at the same time and the molded article is taken out opening the mold. In this time the fixing ring 5 does not retire, pushes and holds the film 3 without following the retiring action of the core 2 and only the printed pattern is separated from a base layer and transferred to the surface of the molded article.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves inserting a transfer film on which a surface pattern is printed onto a molded product into a predetermined position in the entire mold, injecting a molding base material such as plastic into the mold, The present invention relates to a printing method for injection molded products, in which a printing pattern is transferred from a transfer film to the molded product in a mold at the same time as the molded product is obtained.

Conventionally, methods for printing surface patterns on injection molded products made of resin base materials such as plastics include hot stamping, in which a printed layer of foil is transferred to the molded product by heating and pressure, and the printing pattern is printed on kraft transfer paper. A transfer printing method in which a coating is formed on the screen that prevents ink from passing through according to the printing pattern, and the ink is slid onto the screen with a spatula and transferred to the molded product directly under the screen. The silk screen printing method obtains a printed pattern, the dry offset method transfers the ink from the letterpress to a plunket onto the molded product, and the reverse printing method is applied to a transparent film made of the same material as the fabric of the molded product and this film is placed inside the mold. The printed pattern is embedded into the molded product by attaching the film to the molded product and integrating the film and molded product in the mold during the injection molding process. Color molding methods are known and are extremely useful as a simple and quick means of forming surface patterns for purposes such as decoration of molded products, function indication in terms of use, and surface protection.However, conventional printing methods inject・
All methods, except for the pattern method, print patterns such as letters, figures, symbols, patterns, etc. after the injection molding of the molded product is completed. Therefore, if the manufacturing process requires at least two steps: an injection molding step into a mold and a printing step, and the surface of the injection molded product is composed of a surface with many unevenness, There is a problem in that printing, especially printing on uneven areas, becomes extremely difficult. Meanwhile, Innoject
The O-pattern method has the advantage of shortening the manufacturing process to one step because the printed pattern is embedded on the surface of the molded product at the same time as injection molding. However, in the method of integrating this printed film into the molded product, It is necessary to use a transparent film that is made of the same material as the product, and is subject to severe restrictions in terms of materials, which limits its range of use. After the twisted film is installed in a mold, the film tends to be misaligned during plastic injection molding, making it impossible to accurately form a printing pattern at a predetermined position on a molded product.

In addition to the above-mentioned inkjet-o-pattern method, techniques for simultaneously performing injection molding and pattern printing in a mold include Japanese Patent Publication No. 52-31388 and Japanese Patent Application Laid-open No. 52-470.
As shown in No. 57, a metal foil or thin metal plate coated with an adhesive that can be bonded to the molded product is placed in a mold and injection molded to give a metallic luster to the surface of the molded product. Techniques for simultaneous formation are known. However, this method cannot be applied when only complex patterns such as letters and symbols are printed locally on the surface of the molded product, and the pressure during injection molding causes the metal foil to become unevenly plastic. There was a concern that cracks would occur in the metal foil due to the deformation force.

In view of the above-mentioned problems, the present invention makes it possible to perform injection molding and pattern printing at the same time by making full use of technical means, eliminates material constraints, and accurately places all types of molded products at predetermined positions. It is an object of the present invention to provide a new and useful method for printing injection molded articles that can form a printed pattern.

Hereinafter, the present invention will be explained according to embodiments with reference to the drawings.

1(A), (B), and (C) are manufacturing process diagrams of an injection molded article illustrating one embodiment of the present invention. The injection mold consists of a cavity 1 and a core 2. FIG. A film 3 having a transfer printing pattern formed on one side is seated in the cavity 1 by a bottle 4. The film 3 is a tape-shaped material stored in a supply source, and a printing pattern is continuously formed on the molded product. When the injection molding is completed, the molds are successively fed out to the molding position in the cavity 1 for each printing pattern. The specific structure of the film 3 in this embodiment is such that necessary characters, figures, symbols, etc. are attached to the polyester resin film having a thickness of about 30 μm to 150 μm, preferably around 75 μm, through an adhesive layer having an appropriate adhesive force. A transfer pattern is printed, and an adhesive is applied onto the pattern as necessary. On the other hand, a metal fixing ring 5 is connected to the core 2 to fix the film 3 at the outer periphery of the injection molding position. The fixed ring 5 is fixedly supported by a reciprocating rod 6 that penetrates the core 2 and moves back and forth by an external driving force such as a hydraulic cylinder or a spring body, and moves back and forth independently of the core 2.

When the film 3 is fed into the female molding part of the cavity L with the printed pattern facing the core 2 and is seated through the bin 4 as shown in FIG.
As shown in FIG.
is fixed. Next, the core 2 moves forward, and the male molded part passes through the inside of the fixing ring 5, pressing the film 3. The film 3 is stretched and deformed into the female molding part by the elastic stress of the polyester resin base layer due to the pressure of the core 2, as shown in FIG. This completes the mold clamping. A plastic base resin 7 is placed between the film 3 and the core 2 in this mold.
For example, polyethylene, ABS, polypropylene,
Supply vinyl chloride, etc. at a predetermined molding pressure. The base material resin 7 is injected by using a conventionally known injection molding nozzle (not shown) and supplying the heated plastic material into the mold while applying pressure from the nozzle side. It is desirable that the molding pressure and injection speed at this time be slightly higher than the conventional normal molding pressure and injection speed.

Further, the mold temperature may be room temperature. When the base resin 7 is injected, the film 3 is stuck along the inner surface of the female molding part of the cavity 1 by the molding pressure of the base resin 7, and the printed pattern formed on the film 3 is adhered to the base resin 7. . At the same time, the base material resin 7 is molded along the shape of the molded part, as shown in Fig. 1 (D
) as shown below.

When injection molding is completed, the mold is opened and the molded product is taken out. In this operation, as shown in FIG. 1(E), by retracting the core 2, the solidified molded product of the base resin 7 follows the core 2 and leaves the cavity 1 together with the transferred printed pattern.

The printed pattern formed on the film 3 is adhered to the base resin 7 during injection molding, and when the mold is opened, the printed pattern is separated from the base layer of the film 3 and transferred to the molded product. Further, when the mold is opened, the fixing ring 5 does not move back, but presses the film 3 around the outer periphery of the molded product. Therefore, due to the action of this fixing ring 5, the film 3 is held stationary on the cavity 1 side without following the retreating movement of the core 2, and only the printed pattern is peeled off from the base layer and is stuck with a stronger adhesive force than the base layer. This will be transferred to the surface of the molded product. The base layer is insoluble in the base resin 7 and is not adhered to the molded product. The molded product moves in conjunction with the core 2 because the supply path for the base material resin 7 to the mold is interposed within the core 2. By taking out the molded product held by the core 2, an injection molded product to which the printed pattern has been transferred is obtained. The film 3 in the cavity 1 that has not yet been printed is discharged, followed by a region of the film 3 having the next consecutively arranged printing pattern to be delivered to the injection molding position in the cavity l, and a similar injection molding operation is carried out. It will be repeated sequentially.

Figure 2 (A) Q3) (C) is a manufacturing process diagram of an injection molded product for a calculator cabinet explaining another embodiment of the present invention. A film 3 on which a printing pattern for transfer is formed is seated in the mold. This frame 4) is still fixed by a fixing ring 5 at the outer periphery of the injection molding area. Fixed ring 5
is fixedly supported by a reciprocating rod 6 that penetrates the core 2 and moves back and forth, and a portion of the fixing ring 5 that corresponds to the base material resin supply path is cut out. The planar shape of this fixing ring 5 is shown in FIG. After the film 3 in the injection molding area is positioned by the fixing ring 5, it is inserted into the cavity l by the core 2.
The mold is stretched into the inner female molding part, and by tightly connecting the cavity l and the core 2, the mold is clamped as shown in FIG. 2(3). An insert 8 for forming a hole in the molded product is inserted into the cavity 1, and the tip of the insert 8 is in contact with the protruding surface of the core 1 via the film 3. There is a minute gap between the insert 8 and the cavity 1 of about 001 to 0.1+w, and the aerodynamic force within the molding area is detected through this minute gap during injection molding. The supply path for the base material resin consists of a line 51 formed in the cavity 1 by the injection molding nozzle, a supply passage 10 in the mold communicating with the sprue 9, and a submarine gate 11 inserted just before the injection molding area. has been done.

When the base resin 7 is supplied from the sprue 9 at a predetermined molding pressure, the base resin 7 flows through the supply passage 10 and the submarine gate 11.
It is injected into the mold between the film 3 and the core 2 through the. Therefore, the film 3 is stuck along the inner surface of the female molding part of the cavity 1 due to the molding pressure of the base resin 7, and the marks i, ; At the same time, the base material resin 7 is molded along the shape of the molded part.Since the air between the cavity 1 and the film 3 cannot escape to the core 2 side, it is bonded to the core 2 side. The air is discharged to the outside through the minute gap formed between the insert 8 and the cavity 1.This air discharge is necessary for molded products with complex shapes to prevent damage to the film 3, sink marks, insufficient adhesion of the printed pattern, etc. Since this is very important, natural discharge using the minute gap or forced exhaust by vacuum suction is used.The state after the injection of the base material resin 7 is completed is shown in Fig. 2 (2).

After the base material resin 7 has solidified, the core 2 is moved back and the mold is opened, as shown in FIG. 2(C). When the core 2 retreats, the fixing ring 5 presses the film 3 to hold it stationary, and only the printed pattern on the film 3 is peeled off from the base layer, and the surface of the molded product moves away from the cavity 1 in conjunction with the core 2. transcribed. Remove the molded product from core 2,
By cutting the base material resin 7 at the submarine gate portion, an injection molded product with the printed pattern transferred thereon is obtained.

As explained in detail above, according to the present invention, only the printing pattern can be transferred and printed from the transfer film to the molded product at the same time as injection molding, and the manufacturing process can be significantly reduced. The base layer of the groove transfer film is not integrated into the molded product, so it is not limited by the material of the molded product, and is the most suitable one considering printing workability, elongation during molding, heat resistance, etc. A highly reproducible and reliable injection molding process can be established.

Since the lume is fixedly positioned around the outer periphery of the injection molding area, the printing pattern can only be positioned by clamping the mold, and when the mold is opened, the printing pattern transferred to the molded product can be easily peeled off from the base layer of the transfer film. I can do it. In addition, the elastic stress of the base layer of the transfer film eliminates local stress on the printed pattern to prevent cracks in the printed pattern, and it also follows the shape of the surface to be formed, ensuring accuracy even on uneven surfaces. Execute transfer printing. Since the printed pattern is supported by this base layer, the pattern shape can be arbitrarily applied, whether it is a metal pattern or an intermittent pattern of letters and symbols.

In addition to the above, the manufacturing method of the present invention has very excellent effects such as meeting the standards 1 H, easy standardization, and being compatible with automated lines, making it effective for mass production processes of injection molded products. It is an outstanding manufacturing technology of technical significance.

[Brief explanation of the drawing]

FIGS. 1(5), (5), (B), (C), (D), and (E) are manufacturing process diagrams of an injection molded product explaining one embodiment of the present invention. Fig. 2 (A) Q3) (C) describes another embodiment of the present invention. 1... Cavity, 2... Core, 3... Film, 4... Pin, 5 - Fixing ring , 6... Advance/retract rod, 7... Base material resin, 8... Insert, 11... Submarine Gate agent, patent attorney Yoshihiko Fukushi (and 2 others) (D') Figure 1 201- <E)

Claims (1)

[Claims] 1. Attach the extensible film with a printed surface pattern to the injection molding position in the mold, and after holding the extensible film stationary with a fixed ring around the outer periphery of the injection molding position, place the molding base material into the mold. and a step of releasing the solidified molded product of the molding base material from the mold while the extensible film is held stationary by the fixed ring, and the extensible film is supplied under pressure. A method for printing an injection molded product, comprising transferring and printing a surface pattern of the above onto the surface of the molding base material within the mold.