JP2001001363A - Injection molding simultaneous decoration method and injection molding machine used therefor - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To enable transfer of a decorative sheet to a molded product having a deep drawing. SOLUTION: A decorative sheet S is heated and softened, and a closed space is depressurized to bring the decorative sheet S into close contact with the surface shape of a female cavity surface 24 and pre-mold the same. Injection molding in which a resin in a flowing state is injected and filled into a cavity space formed between the male and female molds after closing the molds 20 and 30, and the resin is solidified and the decorative sheet S is adhered and laminated on the surface of the molded product. In the simultaneous decorating method, the gas temperature of the closed space V between the female cavity surface 24 and the decorative sheet S formed by fixing the decorative sheet S with the sheet clamp 50 is higher than the outside air temperature, and The temperature should be lower than the softening temperature. The decorative sheet S is stretched as a whole to improve its formability, and it is possible to decorate a molded product with a deeper drawing than in the past by simultaneous injection molding, thereby reducing defects caused by insufficient molding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding simultaneous decorating method for forming a pattern by bonding and laminating a decorative sheet on the surface of a resin molded article in the same step as molding of the resin molded article, and injection molding used therefor. About the machine.

[0002]

2. Description of the Related Art Conventionally, as a method of providing a pattern on the surface of a resin molded product, a decorative sheet is inserted between male and female molds of injection molding, and the molds are engaged and clamped. In general, a method of injection-filling a resin sheet and bonding a decorative sheet to the surface of a resin molded product is generally performed. In particular,
A suction hole is provided in the female mold cavity surface, and a decorative sheet is fixed to the parting surface of the peripheral edge of the female mold cavity surface with a clamp to form a sealed space between the decorative sheet and the female mold cavity surface. The space is evacuated from the intake port connected to the vacuum pump and the pressure is reduced by bringing the decorative sheet into close contact with the surface shape of the female mold cavity surface. A resin in a flowing state is injected and filled into a closed space (cavity space) formed therebetween, and the resin is solidified and, at the same time, a decorative sheet is adhesively laminated on the surface of the molded product (Japanese Patent Publication No. Sho 5).
0-19132, JP-A-6-315950, etc.).

[0003]

However, in the above-described conventional simultaneous injection molding decorating method, it is difficult to uniformly apply heat to the decorative sheet. There is a situation in which only the amount of heat that does not cause heat is given to the decorative sheet.
Therefore, when the drawing of the mold is deep, depending on the surface shape of the molded product, the sheet temperature decreases at the center of the cavity during molding of the decorative sheet, and the shape of the mold surface may not be able to be followed. There has been a problem that the decoration sheet cannot be transferred or decorated by lamination.

[0004] The present invention has been made in view of the above problems, and an object of the present invention is to provide a simultaneous injection molding method capable of decorating a molded product having a deep drawing with a decorative sheet. An object of the present invention is to provide a decorating method and an injection molding machine used therefor.

[0005]

In order to achieve the above object, the present invention comprises inserting a decorative sheet between a pair of open male and female molds, and partitioning the decorative sheet around the periphery of the female cavity surface. The surface is fixed with a sheet clamp so that the female mold cavity surface and the decorative sheet are sealed tightly,
After the decorative sheet is heated and softened, the decorative sheet is brought into close contact with the surface shape of the female cavity surface by depressurizing the sealed space, and is preformed by pre-forming.
After the molds are closed, the resin in the fluid state is injected and filled into the cavity space formed between the male and female molds, and the resin is solidified, and at the same time, the decorative sheet is adhered and laminated on the surface of the molded article. In the decorating method, the gas temperature of the closed space between the female mold cavity surface formed by fixing the decorative sheet with the sheet clamp and the decorative sheet is set to a temperature higher than the outside air temperature and lower than the softening temperature of the decorative sheet. It is characterized by doing.

[0006] In carrying out this simultaneous injection molding decorating method, the gas temperature in the closed space between the female cavity surface formed by fixing the decorative sheet with the sheet clamp and the decorative sheet is increased. An injection molding machine provided with a heating mechanism is used.

In this injection molding machine, a heating mechanism supplies a heated air supply source for emitting gas at a predetermined temperature, a passage for sending the gas to a closed space between the female cavity surface and the decorative sheet, and a passage for passing the gas. A switching valve for switching between a heated air supply source and a vacuum pump, a vent for making the pressure in the sealed space equal to the outside pressure, and a leak valve for opening and closing the vent. Be composed.

[0008]

FIG. 1 shows an example of an injection molding machine used in the present invention. In the injection molding machine 10, the female mold 20 has a structure in which a vacuum suction hole 21 or a vacuum suction groove is provided so as to be applicable to vacuum suction molding. A part of the shape of the molded product formed by the above is shaped as the female cavity surface 24. The male mold 30 is fixed to a fixed platen 31 and also to a tie bar 40 (a total of four).
On the other hand, the female die 20 is fixed to a movable plate 22, and the movable plate 22 is slidably penetrated by a tie bar 40. The vacuum suction hole 21 of the female mold 20 is connected to the switching valve 71 through the passage 70.
The switching valve 71 switches the passage 70 between the heating air supply source H and the vacuum pump P. The female mold 20 is provided with a vent 72, and the vent 72 is provided with a leak valve 73 for opening and closing the vent.

Prior to the injection of the resin, the decorative sheet is preformed. In performing this preforming, first, the decorative sheet S inserted between the male and female molds is held by being sandwiched by the receiving chuck 23, and the decorative sheet S is held on the parting surface of the female mold 20 by the sheet clamp 50 with the cavity surface 24. Of the female mold cavity surface 24 and the decorative sheet S
To form a closed space V. This state is shown in FIG.

As described above, the closed space V is formed by the decorative sheet S.
Is formed, the leak valve 73 is opened, and the switching valve 7 is opened.
1 connects the passage 70 to the heated air supply source H to supply heated air into the closed space V. Then, the inside of the sealed space V is replaced with air at a predetermined temperature, and is higher than the outside air temperature (room temperature) and the Vicat softening temperature (JISK) of the decorative sheet.
7206), the decorative sheet S is heated and softened by the hot platen 60 inserted between the two molds. Then, the leak valve 73 is closed, and the switching valve 71 is used.
0 is connected to the vacuum pump P, and the vacuum suction holes 21 of the female mold 20 are
The decorative sheet S is drawn into the female cavity surface 2 as shown in FIGS.
4. Adhere to suction. At this time, the pressure in the sealed space V may be reduced monotonically from the atmospheric pressure to a vacuum at a stretch,
It is preferable to decrease it stepwise. The hot plate is made movable between a space between the male and female molds and a space outside the both molds by a drive mechanism such as a fluid pressure cylinder.

After the preliminary forming of the decorative sheet S is completed, the decorative sheet S is nipped by the sheet chuck 80 for conveyance, and the decorative sheet S is cut in the width direction by the sheet cutter 81. As the sheet cutter 81, cutting tools,
A heating wire or the like is used. In the illustrated example, the sheet cutter 81 is installed on the hot platen 60 and cuts the decorative sheet S in conjunction with bringing the hot platen 60 close to the decorative sheet S. It is also possible to cut the decorative sheet by setting it at 50 and interlocking with pressing and fixing of the sheet. Thereafter, the decorative sheet S is cooled. Alternatively, resin injection described later may be performed without waiting for the cooling of the decorative sheet S. As the hot platen 60 for heating and softening the decorative sheet S, the heating plate 60 is in close contact with the decorative sheet S and is heated by heat conduction, or a radiant heat from a position distant from the decorative sheet S or dielectric heating. (The heating plate 60 shown in FIG. 1 is of this type).

After completion of the preforming of the decorative sheet S as shown in FIG. 3, the hot platen 60 is retracted to an external standby position (not shown) between the male and female molds as shown in FIG. By operating the piston 91, the female die 20 with the decorative sheet S in close contact therewith is combined with the male die 30 while sliding on the tie bar 40, and the die is clamped. The cavity C is filled with the molded article forming resin M in a flowing state through the male gate 32 to perform injection molding. And the injected resin M
Is solidified, the decorative sheet S and the resin molded product are bonded and laminated, and then the male and female molds 20, 30 are opened as shown in FIG. Take it out of the mold. The female mold 20 and the male mold 30 are formed of metal such as iron or ceramics.

As the decorative sheet, a sheet which has a base sheet as a minimum element and which has been subjected to a decorative treatment by kneading a colorant, printing a pattern, forming a metal thin film or the like as necessary is used. The base sheet is made of polyolefin resin such as polyethylene, polypropylene, olefin-based thermoplastic elastomer, polymethyl (meth) acrylate, methyl (meth)
Acrylic resin such as acrylate-butyl (meth) acrylate copolymer, polyester resin such as polyethylene terephthalate and polybutylene terephthalate, vinyl chloride resin, polycarbonate resin, polystyrene, ABS
It consists of a sheet of thermoplastic resin such as resin, and the thickness is usually 2
It is about 0 to 300 μm.

[0014] When sufficient adhesion with the injection molded article cannot be obtained on the base sheet or the decoration treatment itself, an adhesive layer is formed on the molded article side. The adhesive is selected according to the combination of the decorative sheet and the material of the molded article. For example, in the case of a combination of a base sheet of a polyolefin resin and a molded product of a polyolefin resin, a chlorinated polyolefin resin (such as chlorinated polypropylene) is used. A two-component curable urethane resin layer is formed on a material sheet, and a chlorinated polyolefin resin layer is formed thereon in this order.

As the decorative sheet, any of a laminate sheet and a transfer sheet can be used.
In the case of the laminate sheet type, the adhesive force between the base sheet and the pattern printing or metal thin film layer constituting the decorative treatment or the adhesive force between the base sheet and the adhesive layer is not peeled off under the use conditions of the molded article. The resin for molding production and the decorative sheet are used while being integrated. On the other hand, in the case of the transfer sheet type, the adhesive strength between the base sheet and the pattern printing or metal thin film layer is set to such an extent that it can be easily peeled off. Then, only the base sheet is peeled off and removed to leave the picture print or the metal thin film adhered to the molded product side.

The resin in the fluid state injected from the male gate is a resin for injection molding, and is actually selected in accordance with required physical properties of the product, cost, and the like. Specifically, polyethylene, polypropylene, polybutene, polyolefin resins such as olefin-based thermoplastic elastomers, acrylonitrile-butadiene-styrene copolymer (ABS), polystyrene resin, acrylonitrile-styrene copolymer, polyvinyl chloride resin, polycarbonate, A resin such as an acrylic resin, which is heated and melted and injected, and cooled to be solidified; a polyurethane resin comprising a polyol and an isocyanate crosslinking agent; an epoxy resin having an amine as a curing agent; an isocyanate; In some cases, an uncured liquid component of a two-component reaction-curable resin such as an unsaturated polyester using a sulfonate, benzoyl peroxide or the like as a curing agent is injected and solidified by a chemical reaction.

[0017]

EXAMPLES (Example) Acrylic resin (polymethyl methacrylate) sheet having a Vicat softening temperature of 110 ° C. (1)
A decorative sheet was prepared by forming a wood-grain pattern layer on one side (25 μm thick) and an adhesive layer thereon. The picture layer is made of acrylic resin and vinyl chloride-vinyl acetate copolymer.
The mixture was formed by using an ink obtained by mixing a 1: 1 weight ratio mixture as a binder and a pigment consisting mainly of red iron oxide, carbon black, titanium white and isoindolinone. The adhesive layer was coated with an adhesive made of vinyl chloride-vinyl acetate copolymer at a thickness of 4 μm.

Using the decorative sheet of the laminate sheet type prepared as described above, simultaneous decoration was performed by an injection molding machine shown in FIG. First, the decorative sheet S is
Of the decorative sheet S and the female mold cavity surface 24 to form a closed space V. Next, with the leak valve 73 opened, the switching valve 71 connects the passage 70 to the heating air supply source H.
To the inside of the sealed space V to supply heated air to keep the sealed space V at 100 ° C., and then insert an infrared radiation type heat with a surface temperature of 350 ° C. inserted from outside of both molds by driving a hydraulic cylinder. The board 60 was heated by approaching the decorative sheet S to a distance of 40 mm. When the heating and softening of the decorative sheet S is completed, the leak valve 73 is closed to shut off the closed space V from the outside.
0 is switched from the heating air supply source H to the vacuum pump P, suction is performed by the vacuum pump P, and the air pressure in the closed space V is reduced. As shown in FIGS. 24, and the preforming was completed.

Next, the hot platen 60 is retracted to a standby position (not shown) outside the male and female molds, the vacuum pump 70 is shut off by the switching valve 71, and the male and female molds are closed as shown in FIG. Tighten the male gate 32 into the cavity space C between the two molds.
Was injected and filled with a 220 ° C. ABS resin, which was cooled and solidified. The temperature of both molds at this time was 60 ° C. Subsequently, as shown in FIG. 5, both molds were opened, and a molded product N having the decorative sheet S laminated and integrated on the surface was taken out.

(Comparative Example) A decorative molded article was manufactured in the same manner as in the example except that the decorative sheet was heated by the hot platen 60 without supplying heated air to the closed space.

Each decorative molded article obtained in the example and the comparative example was visually inspected for the presence or absence of peeling of the decorative sheet from the molded article. As a result, the decorative sheet peeled in the molded article of the comparative example. However, no peeling of the decorative sheet was observed in the molded article of the example.

[0022]

As described above, according to the present invention,
When performing simultaneous injection molding decoration, the gas temperature of the closed space between the female mold cavity surface and the decorative sheet formed by fixing the decorative sheet with the sheet clamp, higher than the outside air temperature and from the softening temperature of the decorative sheet By setting the temperature in a low range, the decorative sheet is stretched as a whole and its formability is improved, and it is possible to decorate a molded product with a deeper drawing than ever before by injection molding and reduce defects caused by insufficient molding. Can be done.

[Brief description of the drawings]

FIG. 1 is a partially cutaway view showing an example of an injection molding machine used in the present invention.

FIG. 2 is a partially cutaway view of the injection molding machine in a state in which the decorative sheet is being preformed.

FIG. 3 is a partially cutaway view of the injection molding machine shown after the preliminary molding of the decorative sheet has been completed.

FIG. 4 is a partially cutaway view of an injection molding machine showing a state in which a molding resin is injected after the preliminary molding of the decorative sheet is completed.

FIG. 5 is a partially cutaway view of an injection molding machine showing a state in which both male and female molds are opened and a resin molded product is taken out after injection molding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Injection molding machine 20 Female type 21 Suction hole 22 Movable plate 23 Reception chuck 30 Male type 31 Fixed plate 32 Gate 40 Tie bar 50 Sheet clamp 60 Hot plate 70 Passage 71 Switching valve 72 Vent hole 73 Leak valve 80 Sheet chuck 81 Sheet cutter 90 Fluid pressure cylinder 91 Piston S Decorative sheet C Cavity M Resin for forming molded product N Resin molded product V Closed space

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29C 45/78 B29C 45/78 F term (Reference) 4F202 AA13 AD05 AD09 AF08 AF10 AG03 CA11 CB01 CB13 CB19 CB28 CK11 CN01 CN25 CP01 CQ01 CQ06 4F206 AA13 AD05 AD09 AF08 AF10 AG03 JA07 JB13 JB19 JB28 JF05 JF35 JN26 JN43 JQ81

Claims (3)

[Claims] 1. A decorative sheet is inserted between a pair of opened male and female molds, and the decorative sheet is held between the female mold cavity surface and the decorative sheet by a sheet clamp on a parting surface of a peripheral edge of the female mold cavity surface. In a state that it is fixed so that it is sealed,
After the decorative sheet is heated and softened, the decorative sheet is brought into close contact with the surface shape of the female cavity surface by depressurizing the sealed space, and is preformed by pre-forming.
After the molds are closed, the resin in the fluid state is injected and filled into the cavity space formed between the male and female molds, and the resin is solidified, and at the same time, the decorative sheet is adhered and laminated on the surface of the molded article. In the decorating method, the gas temperature of the closed space between the female mold cavity surface formed by fixing the decorative sheet with the sheet clamp and the decorative sheet is set to a temperature higher than the outside air temperature and lower than the softening temperature of the decorative sheet. A simultaneous injection molding decoration method. 2. An injection molding machine used in the simultaneous injection molding and decorating method according to claim 1, wherein the decorative sheet is provided between a female cavity surface formed by fixing a decorative sheet with a sheet clamp and the decorative sheet. An injection molding machine provided with a heating mechanism for raising a gas temperature in a closed space. 3. A heating mechanism supplies a heated air supply source for emitting a gas having a predetermined temperature, a passage for sending the gas to a closed space between the female cavity surface and the decorative sheet, and a heating air supply passage for the passage. A switching valve for switching between a source and a vacuum pump, a vent for making the pressure in the sealed space equal to the outside pressure, and a leak valve for opening and closing the vent. Item 3. An injection molding machine according to Item 2.