JPH0584769A - Production of injection molded product - Google Patents

Abstract

PURPOSE:To apply a printing pattern to the recessed surface of a molded product simultaneously with molding by bringing a heat-shrinkable sheet into close contact with the protruding part of the molding surface of an injection mold under heating and closing the injection mold to inject a main body molding resin in the cavity of the mold to mold the same. CONSTITUTION:A heat-shrinkable PP sheet 2 is brought into close contact with the protruding part 121 of a male mold 12 under heating. Subsequently, the mold 1 is closed and a main body molding PP resin is injected in the cavity of the mold 1 to be subjected to injection molding to obtain a desired injection molded product. By this constitution, a printing pattern can be applied to the recessed part of the molded product simultaneously with molding and surface decoration of excellent appearance is applied to the outer surface of the molded product and the functions of surface hardness, weatherability and soft touch properties can be imparted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to improve the surface hardness and weather resistance by applying a printing pattern to the concave portions of vehicle bodies such as automobiles and motorcycles, housings such as office automation equipment and home appliances, and stationery. The present invention relates to a method for manufacturing an injection-molded article used in a field that needs to be provided with a soft touch function.

[0002]

2. Description of the Related Art In recent years, as a method for increasing the added value of plastic molded products such as daily necessities and automobile interiors, a method of transferring a pattern printed on a sheet to the surface of the molded product at the same time as injection molding and various characteristics have been developed. For example, a method of attaching the provided thermoplastic resin sheet has been performed.

As a specific example thereof, for example, Japanese Patent Laid-Open No. 59-
As described in JP-A-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 supplied to an injection molding die so that the sheet faces the injection molding female die. Hold and then heat the part of the sheet that is held facing the female mold between the heating member and the female mold, and make the sheet adhere to the surface of the mold (pre-molding) by vacuum / pressure molding (injection molding). A device for performing is proposed.

[0004]

Problems to be Solved by the Invention JP-A-59-2028
According to the method disclosed in Japanese Patent No. 30, it is possible to transfer the pattern printed on the sheet to the surface of the deep-drawn molded product or to attach the thermoplastic resin sheet. However, according to the above method, since the thermoplastic resin sheet is preformed on the surface of the female mold, there is a problem that only a convex pattern of the molded product can be provided with a printed pattern or the like.

The present invention has been made for the purpose of solving the above-mentioned conventional problems and providing a method for producing an injection-molded article capable of forming a pattern such as printing on the concave surface of the article simultaneously with molding. It is a thing.

[0006]

According to the present invention, a sheet having heat shrinkability is heated and brought into close contact with a convex portion of a mold surface of an injection molding die, and then the injection molding die is closed to form a cavity. It is a method of manufacturing an injection-molded article, in which a resin for molding a main body is injection-molded. In the present invention, the heat-shrinkable sheet includes, for example, polyvinyl chloride, polyethylene, cross-linked polyethylene, polypropylene, polyethylene terephthalate, polystyrene, foamed polyolefin, and the like.
A uniaxially or biaxially stretched sheet having heat shrinkability is used. The heat shrinkage rate of the sheet having heat shrinkability is
It is appropriately determined according to the shape of the intended injection-molded product.

The heat-shrinkable sheet used in the present invention includes, for example, the following forms, in addition to the case of only the heat-shrinkable sheet (base layer). A sheet with patterns such as printing on the surface of the base layer by gravure, silk screen, offset, etc.

A sheet in which a release layer is provided on the surface of the base layer, and a pattern such as printing is formed on the release layer by gravure, silk screen, offset or the like. A release layer is provided on the surface of the base layer, a clear layer is provided thereon, and then a gravure, silk screen,
A sheet that has been patterned by printing, such as by offsetting.

The above-mentioned clear layer is cured by irradiating light with ordinary polymer compounds such as acryl, urethane, and fluorine, and a low molecular compound having a vinyl group and a photoinitiator added to these materials. A possible material is used.

In this case, the clear layer is formed as follows. When the thickness of the clear layer is relatively thin, it is preferably produced by a casting method or a laminating method.

In the case of the casting method, a solution obtained by sufficiently dissolving or dispersing the resin composition in an organic solvent is used as a base layer provided with a release layer by using an apparatus such as a bar coater or a knife coater (heat shrinkability). A sheet having a layer) and then dried to remove a solvent to form a clear layer.

In the case of the laminating method, first, a solution obtained by sufficiently dissolving or dispersing the resin composition in an organic solvent is used to prepare a process paper (usually silicone with a device such as a bar coater or a knife coater). Coated on the surface treated polyethylene terephthalate or paper),
Then, it is dried to remove the solvent to form a clear layer. Next, a base layer (sheet having heat shrinkability) is laminated and pressure-bonded by (heating) a roll press, or an adhesive layer is provided at an interface between both layers and pressure-bonded by a roll press to form a clear layer. The process paper used in the production can be used as a protective sheet.

When the thickness of the clear layer is large, for example, before forming the sheet (base layer) having heat shrinkability by stretching, the clear layer is provided by the above-mentioned method, and then stretched. Create a sheet.

As the resin for molding the main body used in the present invention,
Any material used for injection molding can be used, such as polystyrene, acrylic resin,
Polycarbonate, polyvinyl chloride, polyethylene, polypropylene, acrylonitrile-butadiene-styrene copolymer (ABS), modified polyphenylene oxide,
Examples thereof include polyphenylene sulfide, polyether imide, polyether ether ketone, polyethylene sulfide, liquid crystal resin, glass fiber reinforced polyester, glass fiber reinforced epoxy resin and glass fiber reinforced acrylic resin.

Examples of injection-molded articles suitably manufactured in the present invention include vehicle bodies such as automobiles and motorcycles, housings for OA equipment and home appliances, stationery and the like.

[0016]

In the present invention, after the heat-shrinkable sheet is brought into close contact with the convex portion of the mold surface of the injection molding die by heating,
By closing the injection molding die and injection-molding the resin for molding the main body into the cavity, it is possible to form patterns such as printing on the recesses of the molded product at the same time as molding. It is possible to perform surface decoration with an excellent appearance, and to impart functions of surface hardness, weather resistance improvement, and soft touch property.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments of the drawings. First, an example of an injection molding die used in the present invention will be described with reference to FIG.

Reference numeral 1 denotes an injection molding die used in the present invention, which comprises a fixed side female die 11 and a moving side male die 12,
Between the female mold 11 and the male mold 12, there is provided a cavity 13 having an inner surface shape corresponding to the outer surface shape of a molded product having a recess on the surface.

That is, the female die 11 is provided with a concave portion 111 forming a convex surface of a molded product to be molded, and the male die 12 is formed with a convex portion 121 forming a concave surface of the molded product and an end surface. And an end face forming part 122 that is provided.

When the die 1 is closed, the concave portion 111 of the female die 11, the convex portion 121 of the male die 12 and the end face forming portion 1 are formed.
Cavity 13 where the part surrounded by 22 is for molding the molded product
It is said that.

When the mold 1 is opened, a fixing frame 3 for fixing the heat-shrinkable sheet 2 shown in FIGS. 2 to 4 between the female mold 11 and the male mold 12, and a warm frame. A heating device 4 using wind, infrared rays, ultraviolet rays, or the like is introduced. In addition, male 12
When heating the surface of 100 ° C. or higher, the heating device 4 does not necessarily have to be used.

The fixed frame 3 has a plurality of window portions 3 in the shape of two ladders.
The heat-shrinkable sheet 2 is sandwiched between the frames 31 provided with two, and the window portion 32 is moved by one frame for each shot, and the heat-shrinkable sheet 2 is moved to the injection mold. It is possible to supply continuously. The mold 1 can be closed through the window 32.

Next, FIG. 2 sequentially showing an example of the process of the present invention.
~ It demonstrates with reference to FIG. First, as shown in FIG. 2, the mold 1 is opened, and the heat-shrinkable sheet 2 is sandwiched between the two frames 31 of the fixed frame 3 on the side surface of the male mold 12 from which the convex portion 121 projects. Supplied by.

Next, as shown in FIG. 3, the window portion 3 of the fixed frame 3 is shown.
The sheet 2 having the heat shrinkability of the portion 2 is pressed against the convex portion 121 of the male die 12 and heated by the heating device 4. As a result, the heat-shrinkable sheet 2 is heat-shrinked and comes into close contact with the surfaces of the convex portions 121 and the short-side surface forming portions 122 of the male die 12.

After that, the heating device 4 is removed, and the mold 1 is closed through the window 32 of the fixed frame 3 as shown in FIG. Inside the mold 1, the male mold 1 with the sheet 2 closely attached to the surface
The cavity 13 is formed between the convex portion 121 and the short surface forming portion 122 of No. 2 and the concave portion 111 of the female mold 11. A resin for molding a main body melted by an injection molding machine (not shown) is injected into the cavity 13 through a sprue 112 of a female mold 11.

After a lapse of a predetermined time and cooling in the mold 1, the mold 1 is opened, the molded product is taken out, and the sheet 2 protruding from the end face of the molded product is cut, as shown in FIG. , The coating 5 formed by the sheet 2 on the outer surface of the molded article body 51
An injection molded product 5 coated with 2 is obtained.

Example 1 Using the mold 1 shown in FIG. 1, according to the above steps shown in FIGS. 2 to 4, a coated molded article as shown in FIG. 5 was formed under the following conditions.

As the sheet 2 having heat shrinkability, the film thickness 4 is
A biaxially stretched polypropylene (PP) sheet of 0 μm (heat shrinkage of 40% in the longitudinal direction at 120 ° C.) having a stone pattern printed thereon was used, and
It was heated at 0 ° C. for 30 seconds and brought into close contact with the convex portion 121 of the male mold 12. Further, PP resin (manufactured by Mitsubishi Petrochemical Co., Ltd .: trade name “BC3”) was used as the resin for molding the main body, and the nozzle tip temperature was 220 ° C. in the cavity 13 where the temperature of the female mold 11 was 80 ° C. from the injection molding machine. The molten main body molding resin was injection molded at an injection speed of 50 mm / sec.

As a result, a coating 52 made of a PP sheet with a stone pattern printed on the outer surface of the PP molded article body 51.
It was possible to obtain an injection-molded product 5 coated with. The appearance of the injection-molded product 5 was good.

Example 2 As a sheet 2 having a heat shrinkability, a stone pattern is printed on a biaxially stretched polyethylene terephthalate (PET) sheet having a film thickness of 50 μm (heat shrinkage rate of 40% in the longitudinal direction at 100 ° C.). Except that the sheet 2 was heated by the far infrared heating device 4 at 100 ° C. for 30 seconds.
An injection-molded article was molded in the same manner as in Example 1.

As a result, the coating 5 made of a PET sheet on which the stone pattern is printed is formed on the outer surface of the molded body 51 made of PP.
An injection-molded article 5 coated with 2 could be obtained. The appearance of the injection-molded product 5 was good.

Example 3 As the heat-shrinkable sheet 2, a biaxially stretched PET sheet having a film thickness of 40 μm (heat shrinkage in the longitudinal direction at 100 ° C. of 70%) was printed with a stone pattern. The injection-molded article was molded in the same manner as in Example 1 except that the sheet 2 was heated by the far infrared heating device 4 at 100 ° C. for 30 seconds.

As a result, the coating 5 made of a PET sheet on which a stone pattern is printed is formed on the outer surface of the molded body 51 made of PP.
An injection-molded article 5 coated with 2 could be obtained. The appearance of the injection-molded product 5 was good.

Example 4 As the heat-shrinkable sheet 2, a photo-curable resin composition [ethyl acetate was applied onto a biaxially stretched PET sheet having a thickness of 40 μm (heat shrinkage in the longitudinal direction at 100 ° C .: 70%). In 300 parts by weight, 100 parts by weight of an acrylic resin (manufactured by Kyowa Gas Chemical Co., Ltd .: trade name "Parapet beads"), an acrylate monomer (manufactured by Nippon Kayaku Co .: trade name "KAYARAD D"
PCA-20 ") 50 parts by weight, 4 parts by weight of 2,4,6-trimethylbenzoyldiphenylphosphine oxide as a photopolymerization initiator, and 2 parts by weight of N-methyldiethanolamine are mixed to prepare a curable resin composition. It is applied to the release surface of a polyethylene phthalate (PET) film, dried at 80 ° C. for 5 minutes, and then the uncured product obtained by peeling off the PET film] is applied and dried to obtain a film thickness. A photocurable resin layer having a thickness of 30 μm was provided, and a stone pattern was printed on the photocurable resin layer, the sheet 2 was heated by the far infrared heating device 4 at 100 ° C. for 30 seconds, and after injection molding, An injection molded article was molded in the same manner as in Example 1 except that the photocurable resin was irradiated with ultraviolet rays from a high pressure mercury lamp.

As a result, P having a photocurable resin layer on which a stone pattern is printed is formed on the outer surface of the molded article body 51 made of PP.
It was possible to obtain the injection-molded article 5 coated with the coating 52 of the ET sheet. The appearance of the injection-molded product 5 was good.

[0036]

[Effect] In the present invention, because of the above-mentioned constitution, it is possible to form a pattern such as printing on the concave portion of the molded product at the same time as the molding, thereby providing an excellent appearance on the outer surface of the molded product. Add surface decoration, improve surface hardness, weather resistance,
A soft touch function can be added.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an example of a mold used in the present invention.

FIG. 2 is a vertical sectional view illustrating an example of a process of the present invention.

FIG. 3 is a vertical cross-sectional view illustrating an example of the process of the present invention.

FIG. 4 is a vertical cross-sectional view illustrating an example of the process of the present invention.

FIG. 5 is a vertical cross-sectional view showing an example of an injection-molded article obtained by the present invention.

[Explanation of symbols]

 1 Mold 2 Sheet 3 Fixed Frame 4 Heating Plate 5 Molded Product 11 Female Mold 12 Male Mold 13 Cavity 51 Molded Product Main Body 52 Coating 111 Recess 121 121 Convex 122 End Face Forming Part

Claims (1)

[Claims] 1. An injection molding die is closed after a heat-shrinkable sheet is brought into close contact with a convex portion of a mold surface of the injection molding die by heating, and a resin for molding a main body is injection-molded in a cavity. A method for manufacturing an injection-molded article, which is characterized by the above.