JPH0524070A - Manufacture of injection molded product - Google Patents

Abstract

PURPOSE:To obtain an injection molded product where thinning of a film thickness of a sheet to be molded within a female mold is reduced, it does not happen that the sheet at a corner part becomes too thin even in a deep drawn molded product, it has comparatively uniform facial properties and a desired pattern. CONSTITUTION:A sheet 2 is held between a female mold 3 possessing a cavity 4, a recessed stepped part 10 provided in the circumference of an opening a cavity 4, a recessed stepped part 10 provided in the circumference of an opening of the cavity 4 and an air blow-off port 3b provided in the recessed stepped part 10 and a heating template 1 possessing a vent port 1a. Then simultaneously with blowing-off of gas through the vent port 1a of the heating template 1, gas is blown off through the air blow-off port 3b and the sheet 2 is arranged within the cavity 4. Then the inside of the cavity 4 is decompressed and the sheet 2 is molded within the cavity 4. Then resin 7 is injected within the cavity 4 and an injection molded product is manufactured after that.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an injection-molded article in which a sheet is preliminarily attached in a cavity of a female mold and then the mold is clamped for injection molding. Injection molded products in fields with surface decoration, from vehicle bodies such as motorcycles to housings and stationery for OA equipment and home appliances, and in fields requiring surface hardness, weather resistance improvement, soft touch and other functions. The present invention relates to a manufacturing method of.

[0002]

2. Description of the Related Art In recent years, as a method for increasing the added value of plastics moldings such as daily necessities and automobile interiors, a method of transferring a pattern printed on a sheet at the same time as injection molding,
For example, a method of attaching a thermoplastic sheet is used. For example, in Japanese Unexamined Patent Publication No. 59-202830, a continuous sheet on which a pattern is printed is sandwiched between a heating member having a ventilation hole and a frame member and then supplied to an injection molding die to form the sheet by injection molding. The sheet is held facing the female die, and then the portion of the sheet held facing the female die is heated between the heating member and the female die and the sheet is brought into close contact with the die surface by vacuum / pressure molding ( An apparatus has been proposed which performs injection molding by preforming.

[0003]

According to the method disclosed in Japanese Patent Laid-Open No. 59-202830, it is possible to transfer a pattern printed on a sheet to the surface of a deep-drawn molded article or to attach a thermoplastic sheet. Is possible. However, when the sheet is preformed into a female mold, the sheet is greatly stretched at the corners of the mold, etc., so the film thickness of the sheet becomes extremely thin in some parts, and the appearance of the obtained molded product deteriorates. Or there may be a problem with durability.

The present invention has solved the above-mentioned problems, and an object thereof is to increase the film thickness of a sheet at the time of molding, and to make a sheet thin portion such as a corner portion of a deep drawn molded product. It is an object of the present invention to provide a method for manufacturing an injection-molded product, which is improved and enables the sheet coating of a deep-drawn product.

[0005]

According to the method of manufacturing an injection-molded article of the present invention, a cavity having an opening on one side, a concave step portion provided on an opening peripheral edge of the cavity, and a gas provided on the concave step portion are provided. A step of heating a sheet by holding a sheet between a female mold having an outlet and a heating plate having a vent, and blowing gas from the vent of the heating plate, and from the gas outlet of the female mold. A step of deforming the sheet by blowing out gas to dispose the sheet in the cavity; a step of bringing the sheet into close contact with the cavity by lowering the pressure in the cavity surrounded by the sheet as compared with the atmospheric pressure; It includes the step of injecting resin into the cavity, which achieves the above objectives.

The present invention will be described below with reference to the drawings.

1 (a) to 1 (f) show an example of an injection molding apparatus used in the manufacturing method of the present invention. This apparatus is provided with a female cavity 4 which is open on one side. The mold 3, the male mold 5 having the convex portion 5a, the heating plate 1, and the injection molding machine 8 for supplying the resin into the cavity 4 are provided.

The heating platen 1 is provided with a suction port 1a having an opening on its surface so as to adsorb the sheet 2 (the surface temperature of the heating platen 1 is preferably uniform).

A concave step portion 10 is provided on the entire circumference or a part of the opening peripheral edge of the cavity 4 of the female mold 3. Therefore, the cavity 4 has a wide mouth portion 4a formed inside the concave step portion 10 and a resin injection portion 4b having an opening area smaller than that of the wide mouth portion 4a formed at the bottom thereof. The recessed step portion 10 is provided with an air blowing port 3b for pushing up and degassing the sheet 2, and the female mold 3 is provided with a ventilation port 3a opening to the bottom of the cavity 4. On the outer surface of the frame of the female die 3, the sealing material 3
c (O ring) is provided.

As shown in FIG. 1 (f), the convex portion 5a of the male die 5 has a convex step portion 5b which faces the concave step portion 10 at a small interval when fitted to the female die 3. A convex portion 5c that protrudes into the resin injection portion 4b is formed. A gate 6 is provided on the convex portion 5c of the male die 5.

In order to manufacture an injection-molded article using such an apparatus, first, as shown in FIG. 1 (b), the sheet 2 is pressed against the heating surface of the heating platen 1 and the sheet 2 is sucked from the suction port 1a. The sheet 2 is heated while being brought into close contact with the heating surface. Next, as shown in FIG. 1C, the heating plate 1 and the sheet 2 are transferred to the side surface of the cavity 4 of the female die 3 and brought into contact with the end surface of the sealing material 3c.

Next, as shown in FIG. 1D, the heating plate 1
The compressed air (gas) of about ² to 10 kg / cm ² is ejected from the ventilation port 1a provided in the, and at the same time, the compressed air of the same degree is ejected from the compressed air blowout port 3b of the female die 3 to the center of the sheet 2. The sheet 2 corresponding to the concave step portion 10 is extended while pushing the portion into the cavity 4. Almost at the same time, a few seconds later, suction is started from the vent 3a of the female die 3, and the air blowout port 3b is switched from the gas blowout state to the suction state. As shown in FIG.
Is molded along the concave step portion 10 of the female mold 3 and the resin injection portion 4b. Then, the heating platen 1 is moved upward, and as shown in FIG.
As shown in (f), the male die 5 is fitted into the female die 3 and the convex step portion 5b of the male die 5 is arranged in the wide mouth portion 4a of the cavity 4.
A resin 7 is injected into the resin injection part 4b from the injection molding machine 8 to manufacture a molded product. When the concave step portion 10 and the convex step portion 5b have a cut-out structure, the mold release and the finishing after the molding are easy.

According to the present invention, the recessed step portion 10 larger than the opening of the resin injection portion 4b is provided on the entire circumference or a part of the opening peripheral edge of the cavity 4 of the female die 3 as described above, and air is blown into the recessed step portion 10. The feature is that the female mold 3 provided with the mouth 3b is used. If the recessed step portion 10 is formed in multiple steps or if the depth from the opening of the cavity 4 is increased, the area of the sheet 2 inserted into the cavity 4 becomes wider, so that the sheet 2 is inserted into the corner portion of the resin injection portion 4b. Can be reduced locally.

The shape of the cavity 4 of the female mold 3 used in the method of the present invention can be changed according to the shape of the injection-molded article to be manufactured.

The term "cavity" generally means a space corresponding to a molded product in a molding die, but in the present invention, the space corresponding to the molded product and the space extended to the space are expedient for convenience. The term "concave" means the whole.

Further, the heating plate 1, the female die 3 and the male die 5 can be placed vertically as well as horizontally. The injection molded article manufactured by the method of the present invention can be used in various applications such as vehicle bodies such as automobiles and motorcycles, interior members, OA equipment, housings and stationery for home electric appliances and the like.

The vents and suction ports provided in the apparatus used in this method are preferably provided in unobtrusive portions and sizes of the finished molded product.

The sheet 2 used in the present invention is preferably formed of a sheet (film) which is malleable at least under heating. According to the method of the present invention, it is possible to use a relatively thin sheet that is easily broken during spreading or an uncured or semi-cured sheet. The material and shape of the sheet are selected according to the purpose of using the sheet, for example, surface decoration, surface strength improvement, weather resistance improvement, soft touch application, or the like. 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, polyether A sheet that contains ether ketone, ionomer, etc. as its main component (the surface may be printed).

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

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

A sheet having functions such as soft touch, antifouling, and antifungal.

A sheet obtained by laminating the above-mentioned sheet.

[0024]

When the heated sheet is brought into close contact with the female mold, the peripheral portion of the sheet is extended by blowing gas from the air outlet provided in the concave step portion, and a wide portion including the portion corresponding to the concave step portion is provided. A sheet of surface area is deformed and disposed in the female cavity. For this reason, the film thickness of the sheet subsequently molded in the resin injection portion can be made thicker than in the case where the recessed step portion is not provided, and the sheet thickness of the corner portion and the like will not be too thin.

[0025]

EXAMPLES (A) Sheet used 1. ABS sheet (A205, manufactured by Sanpo Resin Co., Ltd.)
Film thickness 500 μm).

2. ABS sheet (Sanpo Resin Co., Ltd.)
Manufactured, A106, film thickness 250 μm).

3. Light curable sheet (300 parts of ethyl acetate and 100 parts of Parapet beads manufactured by Kyowa Gas Chemical Co., Ltd.)
Part, Nippon Kayaku Co., Ltd. KAYARAD DPCA-2050 parts, 2,4,6-
A curable resin composition obtained by mixing 4 parts of trimethyl benzoyl diphenylphosphine oxide, 2 parts of N-methyldiethanolamine and 100 parts of rutile type titanium oxide was applied to the release surface of the PET film and dried at 80 ° C for 5 minutes. After that, the uncured photocurable sheet obtained by peeling off the PET film. Film thickness 100
μm).

4. Light-curable sheet (The curable resin composition of Example 3 above was used as an ABS sheet A similar to that of Example 1 above.
A photocurable sheet obtained by coating the composition on 205 and drying at 80 ° C. for 30 minutes. ABS resin layer 500 μm + photocurable resin layer 100 μm).

5. A suede-like sheet (Nipporan 5120 (solid content 30%) manufactured by Nippon Polyurethane Industry Co., Ltd.) was mixed with 100 parts by solid content, and 100 parts of elastic beads EBS100 manufactured by Nippon Shokubai Kagaku Kogyo Co., Ltd. were mixed, and the above-mentioned Example 2 was used. Similar AB
A suede-like sheet obtained by coating on S sheet A106 and drying at 80 ° C. for 30 minutes. ABS resin layer 500 μm
+ Suede-like resin layer 100 μm).

(B) Molding Test Molding was performed as follows. The outline of the cavity of the used female mold is shown in FIG. 2 (a), and the plan view of the entire female mold is shown in FIG. 2 (b). In addition, the heating plate (the one whose surface is fluorinated and has about 0.5 mm vent holes on the surface with about 10 holes / cm ² ) and the female mold are overlapped with each other outside the cavity of the female mold. Make sure to stick out 30mm from the outside diameter evenly. The dimensions (mm) of each part shown in FIG. 2 are as follows.

L ₁ = 150, L ₂ = 90, L ₃ = 30, L ₄
= 180, L ₅ = 120, L ₆ = 30, L ₇ = 90, L ₈ =
60, L ₉ = 30, L ₁₀ = 150, L ₁₁ = 90, L ₁₂ =
30, L ₁₃ = 60, L ₁₄ = 30, L ₂₀ = 15, L ₂₁ = 1
5.

The molding sequence is as follows.

The sheet is sucked into a heating platen and heated.

The sheet and heating plate are moved to the front of the cavity of the female mold for injection molding.

The heating platen is moved toward the female mold and the suction of the heating platen is stopped.

The vent provided in the heating plate is pressurized (discharges compressed air), and the vent of the female concave step is pressurized.
After 0.5 seconds, the vent of the cavity of the female mold is evacuated, and the vent of the concave step of the female is also evacuated to form the sheet.

The vent of the heating platen is kept at normal pressure, and the heating platen is moved away from the female mold and moved upward.

A male mold is fitted and injection molding (ABS resin (ABS-ME, manufactured by Denki Kagaku Kogyo KK) is injected at 230 ° C.) to prepare a molded product.

Table 1 shows the heating temperature of the sheet and the film thickness of each part of the molded sheet (measured during the procedure. The site is shown in FIG. 1 (f)).

The appearance of the finished product was evaluated. The results are shown in Table 1.

[0041]

[Table 1]

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

(B) Molding Test Molding was carried out using a female mold having no recessed step portion.

The molding order is as follows.

The sheet is heated while sucking the heating plate.

The flat pressing plate is removed from the sheet.

The sheet and heating plate are moved to the front of the cavity of the female mold for injection molding.

The heating platen is moved toward the female mold, and the suction of the heating platen is stopped.

A vent is provided in the heating platen under pressure (discharges compressed air) and a female vent is evacuated to form a sheet.

The air vent of the heating platen is set to normal pressure, and the heating platen is moved away from the female mold and moved upward.

A male die is fitted and injection molding (ABS resin (ABS-ME, manufactured by Denki Kagaku Kogyo KK) is injected at 230 ° C.) to prepare a molded product.

Table 2 shows the heating temperature of the sheet and the film thickness of each part (the same as in the example) of the formed sheet.

The appearance of the finished product was evaluated. The results are shown in Table 2.

[0054]

[Table 2]

[0055]

According to the present invention, the film thickness of the sheet formed in the cavity of the female mold is less reduced, and the sheet such as the corner portion is not too thin even in the deep-drawn molded product. Therefore, a molded product having a relatively uniform surface performance and having a desired pattern can be obtained.

[Brief description of drawings]

FIG. 1 is a manufacturing process diagram showing a method for manufacturing an injection-molded article of the present invention.

FIG. 2A is a diagram showing a contour of a cavity used in an embodiment of the present invention. (B) is a plan view showing the shape of a female mold.

[Explanation of symbols]

 1 Heating Plate 1a Vent 2 Sheet 3 Female 3a Vent 3b Air Blowout 3c Sealing Material 4 Cavity 4b Cavity Resin Injection Part 5 Male 5a Convex 6 Gate 7 Resin 8 Injection Molding Machine 10 Recessed Step

Claims (1)

Claim: What is claimed is: 1. A female mold having a cavity having an opening on one side, a recessed step portion provided on an opening peripheral edge of the cavity, and a gas outlet provided in the recessed step portion. A step of heating the sheet by holding the sheet between it and a heating plate having a vent, and blowing gas from the vent of the heating plate and deforming the sheet by blowing gas from the female gas outlet A step of disposing the sheet inside the cavity, a step of bringing the sheet into close contact with the cavity by lowering the pressure inside the cavity surrounded by the sheet as compared with the atmospheric pressure, and a step of injecting a resin into the cavity, A method for producing an injection-molded article, including: