JPH04353412A - Manufacture of injection-molded item - Google Patents

Abstract

PURPOSE:To obtain an injection-molded item having improved outer appearance and performance by a method wherein, for manufacturing a molded item coated with a sheet, uniform printed patterns can be applied to the surface of the molded item or the molded item can be covered with a thermoplastic sheet having even film thickness. CONSTITUTION:A method for manufacturing an injection-molded item comprises the steps of applying a sheet 2 to the surface of a heating board 1 having a degassing port 1a for blowing gas toward the outer side of the board 1 from the central part thereof, bringing the sheet 2 into close contact with the inner surface of a cavity 5 of a female mold 4 by placing the board 1 near the female mold 4 of a mold for injection molding to blow gas from the port 1a of the board 1, and injecting resin 12 into the cavity 5 of the mold after clamping the mold for injection molding.

Description

[Detailed description of the invention]

0001

[Industrial Application Fields] The present invention is applicable to fields involving surface decoration such as vehicle bodies such as automobiles and motorcycles; housings for OA equipment and home appliances; stationery, etc.; The present invention relates to a method for manufacturing injection molded products used in fields that require functionality such as touch.

0002

[Prior Art] In recent years, in order to increase the added value of plastic molded products such as daily necessities and automobile interiors, methods have been developed in which a pattern printed on a sheet is simultaneously transferred during injection molding, and a thermoplastic sheet is added to the surface of the molded product. Methods such as pasting them on

For example, in Japanese Patent Application Laid-Open No. 59-202830, a continuous sheet with a pattern printed thereon is sandwiched between a heating plate having ventilation holes and a frame member, and this sheet is inserted into the female mold of an injection mold. Then, the part of this sheet facing the female mold is heated between the heating plate and the female mold, and the sheet is molded onto the inner surface of the female mold by vacuum/pressure forming. A technique has been proposed in which the materials are brought into close contact (preforming) and then injection molding is performed.

0004

[Problem to be Solved by the Invention] According to the technology disclosed in the above publication, it is possible to transfer a pattern printed on a sheet to the surface of a deep-drawn molded product or to attach a thermoplastic sheet. be.

However, when preforming the sheet into a female mold, the sheet is stretched significantly at the corners of the mold, so the film thickness of the sheet becomes extremely thin in some parts, and the appearance of the resulting molded product deteriorates. In some cases, this may result in a decrease in performance or a problem with durability.

The present invention has solved the above-mentioned problems, and its purpose is to reduce the difference in film thickness of the sheet during preforming of the sheet, and to improve the quality of the molded product even in the production of deep-drawn molded products. It is an object of the present invention to provide a method for producing an injection molded product, which can have a uniform printed pattern on the surface of the product and can be coated with a thermoplastic sheet of uniform thickness, thereby improving its appearance and performance.

[0007]

[Means for Solving the Problems] The method for manufacturing an injection molded product of the present invention includes applying a sheet to the surface of a heating plate that has a vent that can blow out gas from the center of the heating plate toward the outside of the heating plate. a step of coating, a step of disposing the heating plate in the female mold of an injection mold, and a step of bringing the sheet into close contact with the inner surface of the cavity of the female mold by blowing out gas from the vent of the heating plate, and injection molding. The method includes a step of injecting resin into the cavity of the mold after the mold is clamped, thereby achieving the above object.

[0008] The sheet used in the present invention is preferably composed of a sheet (including a film) that is malleable at least under heating, and for example, the following sheets are used.

■ Thermoplastic sheet: polystyrene, acrylic polymer, polycarbonate, polyvinyl chloride, polyethylene, polypropylene, ABS (acrylonitrile-butadiene-styrene copolymer), modified polyphenylene oxide, polyphenylene sulfide, polyetherimide, poly A sheet whose main component is ether ether ketone, ionomer, etc. (the surface may be printed).

■ Thermosetting sheet: An uncured or semi-cured sheet containing a reactive acrylic resin such as acrylic polyol and a blocked isocyanate as main components, a reactive vinyl monomer and/or oligomer, a thermoplastic polymer and /Or an uncured or semi-cured sheet containing a vinyl group-containing polymer and peroxide as main components.

[0011] Photocurable sheet: An uncured or semi-cured sheet containing a thermoplastic polymer, a reactive vinyl monomer, and a photoinitiator as main components.

[0012] ■ Sheets with functions such as soft touch, stain resistance, and mold resistance.

[0013] ■A sheet obtained by laminating the sheets of ■■■ on the sheet of ■ above.

FIGS. 1(a) to 1(e) show an example of an injection molding device used in the manufacturing method of the present invention, and this device includes a female mold 4 having a cavity 5 and a convex portion 10. An injection molding machine 9 for supplying resin into a cavity 5 formed by the female mold 4 and the male mold 6, and a heating plate 1 for heating the sheet 2 are provided.

The heating plate 1 is configured to be movable toward and away from the cavity 5 of the female mold 4, and is provided with driving means (not shown) for driving the heating plate 1.

The female mold 4 is provided with a vent hole 4a that opens into the inner surface of the cavity 5, and a sealing material 8 is provided around the female mold 4.
(O-ring) is provided. A gate 7 is provided on the convex portion 10 of the male mold 6 for supplying resin 12 injected from an injection molding machine 9 into the cavity 5.

The heating plate 1 is made of a material having a predetermined thermal conductivity, and its surface is set at a predetermined temperature. Further, it is preferable that the temperature of the surface of the heating plate 1 is uniform over the entire surface. The material, heat capacity, etc. of this heating plate 1 may be those commonly used.

The heating plate 1 is provided with a large number of vents 1a having openings 1b on its surface, and a communication port 11 communicating with each vent 1a. The communication port 11 is provided inside the heating plate 1, and the other end of the communication port 11 is switchably connected to a suction device and a gas discharge device.

Among the many ventilation holes 1a, the ventilation hole 1a provided in the center of the heating plate 1 is located in the thickness direction of the heating plate 1 (
The ventilation hole 1a, which is formed to face in a direction perpendicular to the surface of the heating plate 1 and is provided at a location other than the center of the heating plate 1, is arranged so that its opening 1b is located on the outside compared to the base. It is formed. The heating plate 1 is arranged in the female mold 4 so that its center coincides with the vicinity of the center of the cavity 5 of the female mold 4.

The diameter of these vent holes 1a can be changed as appropriate depending on the purpose, and can be, for example, about 0.1 to 1 mm. Further, the diameter of each vent 1a may be changed. For example, the diameter of the vent 1a provided at the center of the heating plate 1 may be small, and the diameter of the vent 1a provided at a location other than the center may be large.

[0021] It is preferable that the vents 1a and 4a provided in the apparatus be provided at appropriate locations on the heating plate 1 and the female mold 4, and with appropriate sizes so as not to be noticeable on the molded product.

To manufacture an injection molded product using such an apparatus, first, as shown in FIGS. 1(a) and 1(b), the sheet 2 is heated while suction is being drawn from the vent 1a of the heating plate 1. By pressing the sheet 2 onto the surface of the heating plate 1
The sheet 2 is heated in close contact with the surface of the sheet. Here, the sheet 2 is heated by the heat from the heating plate 1 and its ductility increases.

Next, as shown in FIG. 1(c), the heating plate 1
and transfer the sheet 2 to the side of the cavity 5 of the female mold 4,
It is brought into contact with the end surface of the sealing material 8.

Next, as shown in FIG. 1(d), the heating plate 1
Pressure air (gas) of about 2 to 10 kg/cm2 is ejected from the vent 1a provided in the vent 1a (and sucked from the vent 4a), and the sheet 2 is molded along the inner surface of the cavity 5 of the female mold 4. do.

Here, the air blown out from the vent 1a of the heating plate 1 is blown outward from the center of the heating plate 1, so the sheet 2 is blown out by the pressure of the air. While being pressed toward the cavity 5 side, the sheet 2 is also moved toward the side of the cavity 5, and as a result, the sheet 2 is placed in the female mold 4 with the entire sheet 2 being stretched relatively uniformly. It is molded on the inner surface of the cavity 5.

Next, after moving the heating plate 1 to the upper part, as shown in FIG.
As shown in (e), the male die 6 is fitted into the female die 4, and the resin 1 is injected into the cavity 5 from the injection molding machine 9 through the gate 7.
2 is injected to produce a molded product.

[0027]

[Operation] Gas from each vent of the heating plate is ejected outward from the center of the heating plate, so the sheet moves toward the bottom of the cavity due to the pressure of the ejected gas, and at the same time, the sheet moves closer to the heating plate. The sheet portion will move away from the center of the heating plate.

[0028] As a result, the sheet portions that are normally difficult to stretch can be forcibly stretched, and the thickness of the sheet can be made uniform (the portions that are normally thinner are made thicker). Thus, the sheet is formed into the female mold inner surface in a relatively uniformly stretched state.

[0029]

[Examples] Examples of the method for manufacturing injection molded products of the present invention will be described below.

[0030] In the following examples, "parts" are "parts by weight".
means.

Sheet 1 used in Example (A). ABS sheet (manufactured by Sanpo Jushi Kogyo Co., Ltd., A205,
Film thickness: 500 μm).

2. ABS sheet (manufactured by Sanpo Jushi Kogyo Co., Ltd., A106, film thickness 250 μm).

3. Photocurable sheet (300 parts of ethyl acetate, 100 parapet beads manufactured by Kyowa Gas Chemical Industry Co., Ltd.)
Department, KAYARAD DPCA-2 manufactured by Nippon Kayaku Co., Ltd.
A curable resin composition obtained by mixing 50 parts of 2,4,6-trimethyl benzoyl diphenylphosphine oxide, 2 parts of N-methyldiethanolamine, and 100 parts of rutile titanium oxide was applied to the release surface of the PET film. After coating and drying at 80°C for 60 minutes, P
An uncured photocurable sheet obtained by peeling off an ET film. film thickness 100 μm).

4. Photocurable sheet (the curable resin composition obtained in 3 above was used as an ABS sheet A20 similar to 1 above)
5 and dried at 80°C for 60 minutes. ABS resin layer 500 μm + photocurable resin layer 100 μm).

5. Mix 100 parts of suede-like sheet (Nipporan 5120 (solid content 30%) manufactured by Nippon Polyurethane Industries Co., Ltd. and 100 parts of elastic beads EBS100 manufactured by Nippon Shokubai Chemical Co., Ltd.), and use the same method as in 2 above. A
A suede-like sheet obtained by coating on BS sheet A106 and drying at 80°C for 30 minutes. ABS resin layer 500μ
m + suede-like resin layer 100 μm).

(B) Molding test Molding was performed as follows.

FIG. 2 shows the outline of the cavity 5 of the female mold 4 used.
FIG. 3 shows a plan view of the female mold 4, and FIG. 4 shows the heating plate 1. In addition, the heating plate 1 and the female mold 4 overlap each other.
The outer periphery of the cavity 5 of the female mold 4 was made to protrude uniformly outward by 30 mm from the outer periphery of the cavity 5.

[0038] The surface of the heating plate 1 is treated with fluorine, and there are 10 ventilation holes of about 0.5 mm on the surface.
The one with about 2 layers was used. Further, as shown in FIG. 4, the vents 1a provided in the heating plate 1 were formed radially outward from the center thereof.

The dimensions of each member shown in FIGS. 2 to 4 are (mm)
It is as follows.

[0040] L1=75, L2=45, L3=90, L
4=30, L5=150, L6=30, L7=15, L
8=15, L9=10.

The molding order was as follows.

(2) Heat the sheet while suctioning it onto the surface of the heating plate.

(2) Move the sheet and heating plate to the front of the female mold cavity for injection molding.

(2) Move the heating plate to the female mold side and stop the suction of the heating plate.

(2) Pressurize the vent provided in the heating plate (discharge compressed air), evacuate the vent in the female mold, and form a sheet on the inner surface of the female mold.

(2) Set the ventilation port of the heating plate to normal pressure, remove the heating plate from the female mold, and move it to the upper part.

(2) A male mold is fitted into a female mold, and ABS resin (manufactured by Denki Kagaku Kogyo Co., Ltd., ABS-ME) is injected from an injection molding machine at 230° C. to produce a molded product.

Table 1 shows the heating temperature of the sheet and the film thickness of each part of the formed sheet (measured in step (2); the parts are shown in FIG. 2(a)). The appearance of the obtained product was evaluated. The results are shown in Table 1.

[0049]

[Table 1]

Comparative example (A) Sheet used The sheet used was the same as that used in the example.

(B) Molding Test A molded product was produced in the same manner as in Example 1 above, except that a heating plate provided with vents for blowing air out in the thickness direction of the heating plate was used.

The heating temperature of the sheet and the film thickness of each part of the molded sheet (same as in the example) are shown in the following table. The appearance of the obtained product was evaluated. The results are shown in Table 2.

[0053]

[Table 2]

[0054]

[Effects of the Invention] According to the present invention, it is possible to forcibly stretch the sheet portion that is normally difficult to stretch, and to form the sheet on the inner surface of the female die with a uniform film thickness. In manufacturing, patterns with good appearance can be applied, or molded products with uniform surface functions can be obtained by coating a sheet with a relatively uniform thickness.

In particular, the method of the present invention is excellent as a method for coating the outer periphery of a concave container with a sheet.

[Brief explanation of drawings]

FIGS. 1(a) to 1(e) are process diagrams for explaining an example of the method for manufacturing an injection molded article of the present invention.

FIG. 2(a) is a plan view showing the contour of the cavity shape of the injection molded product manufacturing apparatus of the present invention. (b) is a side view showing the contour of the cavity shape. (c) is a side view showing the contour of the cavity shape.

FIG. 3 is a plan view of a female mold showing an example of a manufacturing apparatus used in the method of manufacturing an injection molded article of the present invention.

FIG. 4(a) is a plan view of the heating plate used in the example. (b) is a sectional view of the heating plate. (c) is a sectional view of the heating plate.

[Explanation of symbols]

1 Heating plate 1a Heating plate vent 2 Sheet 4 Female type 5 Cavity 6 Male type 7 Gate 8 Sealing material 9 Injection molding machine 10 Convex part 11 Communication port 12 Resin

Claims (1)

[Claims] Claim 1: A step of covering the surface of a heating plate with a sheet having a vent that can blow gas from the center of the heating plate toward the outside of the heating plate, and applying the heating to the female mold of an injection mold. The step of placing the plate in close contact with the inner surface of the cavity of the female mold by blowing gas from the vent of the heating plate, and after closing the injection mold, the inside of the cavity of the mold. A method for manufacturing an injection molded product, which includes a step of injecting a resin into the product.