JPH04201215A - Manufacture of injection-molded product - Google Patents

Abstract

PURPOSE:To improve appearance and performance by reducing the film thickness difference of a sheet at the time of performing. CONSTITUTION:A sheet 1 is fast stuck onto the underside of a hot plate 2 by suction and transferred up to the upper position of the cavity 5 of a female mold 4, and the hot plate 2 is arranged onto the top face of the female mold 4 and the end sections of the sheet 1 are brought into contact with the end faces of the frame sections 8 of the female mold 4 and the end sections of the sheet 1 are sucked from the suction ports 4a of the end faces and the end sections of the sheet 1 are fixed onto the end faces of the female mold 4. The hot plate 2 is moved, sheet hold-down members 7 are disposed to the upper section of the female mold 4 and the end sections of the sheet 1 are held among the upper end faces of the frame sections 8 of the female mold 4 and the sheet hold-down members 7. A gas at comparatively high pressure is jetted through the vent hole 4b of the female mold 4, and the sheet 1 is swollen to the side reverse to the female mold 4. The inside of the cavity 5 is brought into a low pressure state by drawing air through the suction port 4a, the sheet 1 is fast held onto the inner surface of the cavity 5 of the female mold 4, a male mold 10 is disposed onto the female mold 4 and a resin is injected into the cavity 5 formed by both molds 4, 5. That is, the sheet is expanded to the side reverse to the cavity of the female mold, and the whole sheet is extended uniformly.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is applicable to vehicle bodies such as automobiles and machine tools, OA equipment,
Regarding the manufacturing method of molded products formed by injection molding such as molding of home appliances or stationery, especially in fields where coating such as painting was applied in the post-process to improve appearance, surface hardness, and weather resistance. This invention relates to a method for manufacturing molded products.

(Prior technology) In recent years, in order to increase the added value of plastic molded products such as daily necessities and automobile interior parts, methods have been developed in which a pattern printed on a sheet is transferred to the surface of the molded product at the same time as injection molding, and thermoplastic A method is used in which a sheet is attached to the surface of a molded product.

For example, in Japanese Patent Application Laid-open No. 59-202830, a continuous sheet with a pattern printed thereon is sandwiched between a heating member having ventilation holes and a frame member, and the sheet is inserted into the female mold of an injection mold. The sheet is placed in an injection mold so as to face each other, and then the part of the sheet facing the female mold is heated between the heating member and the female mold, and the sheet is molded into a female mold by vacuum/pressure forming. A method has been proposed in which the material is brought into close contact with the mold surface (preforming) and then injection molded.

(Problems to be Solved by the Invention) According to the method disclosed in the above publication, it is not possible to transfer a pattern printed on a sheet or to attach a thermoplastic sheet to the surface of a deep-drawn molded product. be. However, when preforming a sheet into a female mold, the sheet is stretched significantly at the corners of the mold, resulting in a thin sheet film, which may reduce the appearance of the resulting molded product or reduce its durability. There were cases where sexual problems arose.

The present invention has solved the above problems, and its purpose is to create a uniform printed pattern even in the production of deep-drawn molded products by reducing the difference in sheet thickness during preforming. It is an object of the present invention to provide a method for producing an injection molded product that can be coated with a thermoplastic sheet to improve appearance and performance.

(Means for Solving the Problems) The method for producing an injection molded product of the present invention involves attaching a sheet to the inner surface of a cavity provided in a female mold, clamping the mold, and then injecting resin into the cavity. In a method for manufacturing a molded product, the peripheral edge of the sheet is held around the cavity of a female mold, and the air pressure inside the cavity surrounded by the sheet is made higher than the outside air pressure, whereby the sheet is placed in the mold cavity. The sheet is inflated to the opposite side, and then the air pressure inside the cavity surrounded by the sheet is made lower than the outside air pressure, so that the sheet is brought into close contact with the inner surface of the cavity, and then the resin is injected. The above objectives are achieved.

The present invention will be explained below based on the drawings.

1 to 5 show an example of an injection molding apparatus used in the manufacturing method of the present invention, and this apparatus includes a female mold 4 having a cavity 5 and a male mold 10 having a convex portion 11. ,
It includes a heating plate 2 and a frame-shaped sheet pressing member 7. The heating plate 2 is provided with a suction port 2a, and is configured to be able to attract the sheet 1 to the lower surface side of the heating plate 2. Suction ports 4a are also provided on the inner surface of the cavity 5 of the female mold 4 and on the end surface of the frame portion 8.
is provided. A gate 12 is provided on the convex portion 11 of the male die 10.
is provided.

To manufacture an injection molded product using such an apparatus, first, as shown in FIG. position, and then, as shown in FIG. 2, by placing the heating plate 2 on the upper surface of the female mold 4, the sheet 1
The end of the mold 4 is brought into contact with the end surface of the frame 8 of the female mold 4. At this time, it is preferable to fix the end of the sheet 1 to the end of the female mold 4 by suctioning from the suction port 4a provided on the end of the frame 8. Next, as shown in FIG. 3, the heating plate 2 is separated from the sheet 1 and moved to the side of the female mold 4, and the sheet pressing member 7 is placed above the female mold 4 and the pressing member 7
The end of the sheet 1 is held between the upper end surface of the frame part 8 of the female mold 4 and the upper end surface of the frame part 8 of the female mold 4. Note that when separating the heating plate 2 from the sheet 1, the sheet 1 may be easily separated by blowing gas out of a vent provided in the heating plate 2.

Thereafter, relatively high pressure gas (such as air) is ejected from the vent hole 4b provided in the female mold 4, thereby inflating the sheet 1 in the opposite direction from the female mold 4, as shown in FIG. The pressure of the compressed air at this time is preferably about 3 Kg/cm2, which is a pressure that does not cause the sheet 1 to deform much. In addition, in order to prevent the sheet 1 from being significantly deformed,
Pressure may be applied from the upper side of the sheet 1 toward the cavity 5 side.

Next, as shown in FIG. 4, by suctioning the gas in the cavity 5 from the suction port 4a in the female mold 4, the pressure inside the cavity 5 is reduced, and the sheet l is brought into close contact with the inner surface of the cavity 5 of the female mold 4. let Next, as shown in FIG. 5, a male mold 10 is placed on the female mold 4, and resin is injected into the cavity 5 formed by both molds 4.5 to obtain a molded product.

Note that the suction port 4a provided in the female mold 4 may also be used as the vent port 4b for pressurized air (and it is preferable that these holes be provided in an inconspicuous part of the finished molded product.

In addition, in the above method, the sheet 1 is transferred to the female die 4 while adsorbed to the lower surface of the heating plate 2, but as shown in FIG.
The end of the sheet 1 may be held between the heating plate 2 and the heating plate 2 and transferred to the female mold 4. Furthermore, as shown in FIG. Compressed air and heating may be performed simultaneously.

The sheet 1 used in the present invention is preferably formed of 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, whethyl ether ketone , a sheet whose main component is polyethylene sulfide.

■Thermosetting sheet: An uncured or semi-cured sheet whose main components are a reactive acrylic resin such as acrylic polyol and a blocked isocyanate; a reactive vinyl monomer and/or oligomer, a thermoplastic polymer and/or a vinyl group uncured or semi-cured sheets, etc. whose main components are a polymer with a peroxide and a peroxide.

■Photocurable sheet: An uncured or semi-cured sheet whose main components are a thermoplastic polymer, a reactive vinyl monomer, and a photoinitiator.

■Sheet made by laminating the sheet ■■ onto the sheet ■■ above.

(Function) Before injecting the resin into the mold, by inflating the sheet toward the side opposite to the female mold cavity, the entire sheet can be spread uniformly. Therefore, when the sheet is subsequently attached to the inner surface of the cavity of the mold, the sheet can be applied in a uniformly stretched state even at the corner of the mold.

(Example) Hereinafter, the present invention will be specifically explained based on Examples.

(A) Sheet Examples 1 and 6 used ABS sheet (manufactured by Royal Resin Industry ■, A205, film thickness 50
0 μm) Examples 2 and 7 ABS sheet (manufactured by Royal Resin Industry ■, A404, film thickness 25
0 μm) Examples 3 and 8 Photocurable sheet This sheet was prepared by adding 300 parts by weight of ethyl acetate, 100 parts by weight of /f Lapet beads (manufactured by Kyowa Gas Chemical Industry ■), and KA
YARAD DPCA-20 (manufactured by Nippon Kayaku ■) 50!
A photocurable resin composition obtained by mixing 1 part of 2.4.6-trimethyl benzoyl diphenylphosphine oxide, 2 parts by weight of N-methyljetanolamine, and 100 parts by weight of rutile titanium oxide. This is an uncured photocurable sheet obtained by coating the release surface of a terephthalate film (hereinafter referred to as PET film), drying it at 80° C. for 5 minutes, and then peeling off the PET film. The film thickness was 100 μm.

Examples 4 and 9 Photocurable sheets This sheet was prepared by coating the photocurable resin composition used in Example 3 above on the same ABS sheet A205 as in Example 1 above, and drying it at 80°C for 30 minutes. This is a photocurable sheet obtained by The film thickness of the sheet is ABS resin resin layer 50
Examples 5 and 10 Suede-like sheet This sheet is
Niraporan 5230 (manufactured by Nippon Polyurethane Industries, Ltd.)
100 parts by weight of solids (30% solids), elastic beads E
100 parts by weight of BS100 (acrylic urethane copolymer manufactured by Nippon Shokubai Chemical Co., Ltd.) was mixed, coated on the same ABS Sea) A2 05 as in Example 1 above, and dried at 80° C. for 30 minutes. It is a suede style sheet. The film thickness of the sheet was an ABS resin layer of 50 m.

(B) -1 Molding Test I (Examples 1 to 5) Molding was performed as follows. The shape of the cavity 5 of the female mold 4 used is shown in FIGS. 8(a) and (1)).

In the figure, the dimensions of each part of the cavity 5 are 200 mm.
mm, L2 is 200mm, L3 is 100mm,
The radius of curvature R was 10 mm.

■Heat the sheet 1 while suctioning it with the heating plate 2 and transport it to a position above the cavity 5 of the female mold 4 for injection molding (Fig. 1)
.

(2) Place the heating plate 2 on the upper surface of the female mold 4, and stop the suction of the heating plate 2 (Fig. 2).

(2) The end of the sheet 1 is brought into contact with the end surface of the female mold 4 by suctioning from the suction port 4a provided on the end surface of the female mold 4.

■ Raise the heating plate 2 and release it from the sheet 1, and hold the end of the sheet 1 between the sheet pressing member 7 and the end surface of the female mold 4,
The sheet 1 is inflated into a hemispherical shape on the side opposite to the cavity 5 of the female mold 4 by the pressurized air from the pressurized air vent 4b in the female mold 4 (Fig. 3).

(2) By suctioning the air inside the cavity 5 through the suction port 4a of the cavity 6, the sheet 1 is brought into close contact with the inner surface of the cavity 5 (FIG. 4).

■Close the mold and put ABS resin (Denki Kagaku Kogyo (iIli!!, ABS-ME) into the cavity 5 at 230"C'7
:” Inject (Figure 5).

The appearance of the injection molded product thus obtained was evaluated.

The results are shown in Table 1. In addition, the heating temperature of the sheet 1 and
Each part of the formed sheet 1 (the parts are (a') in Fig. 8,
(b) and (c)) are also shown in Table 1.

(B)-2 Molding Test H (Examples 6 to 10) Molding was performed as follows. The female mold 4 used was the same as that used in molding test (B)-I.

■Heat the sheet 1 while suctioning it with the heating plate 2 and transport it to a position above the cavity 5 of the female mold 4 for injection molding (Fig. 1)
.

(2) Place the heating plate 2 on the upper surface of the female mold 4, and stop the suction of the heating plate 2 (Fig. 2).

(2) The end of the sheet 1 is fixed to the end surface of the female mold 4 by suctioning through the suction port 4a provided on the end surface of the female mold 4.

■ Raise the heating plate 2 to separate it from the sheet 1, and pinch the end of the sheet 1 between the sheet pressing member 7 and the end surface of the female mold 4,
The sheet 1 is inflated into a hemispherical shape on the side opposite to the cavity 5 of the female mold 4 by compressed air from the vent 4b in the female mold 4 (the third
figure).

■ Make the inside of the cavity 5 a vacuum through the suction port 4a of the cavity 5, place the heating plate 2 on the end face of the female mold 4 again, and
By compressed air from the vent 2b provided in the heating plate 2,
The sheet 1 is brought into close contact with the female mold 4 (FIG. 7).

(2) Clamp the mold and inject 230"C-?" of ABS resin (manufactured by Denki Kagaku Kogyo Co., Ltd., ABS-ME) into the cavity 5 (Fig. 5).

The appearance of the injection molded product thus obtained was evaluated.

The results are shown in Table 2. In addition, the heating temperature of the sheet 1 and
Table 2 also shows the film thickness of each part of the molded sheet (the parts are shown in FIG. 6).

(Comparative Examples 1 to 5) (A) Sheet The same sheet as that used in Examples 1 to 5 was used.

(B) Molding test Molding was performed as follows.

■Heat the sheet l while suctioning it with the heating plate 2 and transport it to a position above the cavity 5 of the female mold 4 for injection molding (Fig. 1)
.

(2) Place the heating plate 2 on the upper surface of the female mold 4, and stop the suction of the heating plate 2 (Fig. 2).

■While sucking through the suction port 4a provided in the female mold 4,
The sheet 1 is brought into close contact with the inner surface of the cavity 5 of the female mold 4 by means of compressed air from the vent 2b provided in the heating plate 2 (FIG. 7).

(2) After the mold is clamped, As5m resin (manufactured by Denki Kagaku Kogyo (2), ABS-ME) is injected at 230'C'' into the cavity 5 (Fig. 5).

The appearance of the obtained injection molded product was evaluated. Table 3 shows the results.
Shown below. Table 3 also shows the heating temperature of the sheet and the film thickness of each part of the formed sheet (the parts are shown in FIG. 8).

(Margin below) (Effects of the Invention) According to the present invention, the sheet can be brought into close contact with the sheet in a uniformly stretched state even at the corner of the cavity, so that the film thickness of the sheet at the corner becomes thinner. Without a doubt, -
Resin can be injected into sheets of various thicknesses. Furthermore, if a sheet having a printed pattern on its surface is used as the sheet that is brought into close contact with the cavity, the resin can be injected onto the sheet that is brought into close contact with the cavity with a uniform thickness. Therefore, there is an advantage that an injection molded product with excellent appearance and performance can be obtained.

4. Don't worry! B FIGS. 1 to 5 are explanatory diagrams showing one embodiment of the method for manufacturing an injection molded product of the present invention, and FIGS. 6 and 7 are respectively other embodiments of the method for manufacturing an injection molded product of the present invention. FIGS. 8(a) and 8(b) are a plan view and a sectional view of the female mold.

l... Sheet, 2... Heating plate, 2a... Suction port,
2b...ventilation port, 4...female type, 4a...suction port,
4b... Vent hole, 5... Cavity, 6... Sheet clamping frame, 7... Sheet pressing member, 10... Male mold.

that's all

Claims (1)

[Claims] 1. In a method for manufacturing an injection molded product in which a sheet is attached to the inner surface of a cavity provided in a female mold, the mold is clamped, and resin is injected into the cavity, the peripheral edge of the sheet is attached to the inner surface of the cavity of the female mold. The sheet is inflated to the opposite side of the mold cavity by making the air pressure inside the cavity surrounded by the sheet higher than the outside air pressure while being held around the sheet, and then the air pressure inside the cavity surrounded by the sheet is released. A method for producing an injection molded product, which is characterized in that the sheet is brought into close contact with the inner surface of a cavity by lowering the atmospheric pressure compared to the atmospheric pressure, and then resin is injected.