JP3296938B2 - Resin molded product and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molded product and a method for producing the same, and more particularly, to a resin molded product in which a net is buried near the surface of the molded product by injection molding and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, a laminated product in which a copper fiber net, a conductive polyester cloth, or the like is inserted between two glass or transparent resin plates has been used as a front plate, a window, and the like for preventing electromagnetic interference. Since the production of the laminated product is performed by a casting method, a lamination method, or the like, there have been problems such as complicated processes, a low yield, and a high production cost. On the other hand, there has been proposed a method of manufacturing a molded product by injection molding using a molding material containing a conductive filler such as aluminum flake, carbon fiber, and copper fiber. Application Issued January 1994 220
225 pages), problems such as abrasion of screws and cylinders of an injection molding machine, reduction in conductivity due to uneven distribution of fillers, and occurrence of poor appearance due to exposure of fillers to the surface of a molded product have not been sufficiently solved. There was a problem.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a resin molded product in which a net, particularly a conductive net is buried in the vicinity of the surface of the molded product, and a simple production method thereof. It is in.

[0004]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted intensive studies on a method of uniformly and simply embedding a net-like material in a resin. Injection molding with a synthetic resin film or the like having poor thermal conductivity interposed between the resin and the mesh material prevents the formation of a cooled solidified layer on the surface of the molded product due to the heat insulation effect. And found that it was buried in the part, and completed the present invention.

Namely, the object according to the present invention, for molding at least one surface constructed from low thermal conductivity material relative to other aspects of the cavity consisting <br/> molded article is molded Using a mold, place a mesh on the cavity surface with poor thermal conductivity in the mold, inject molten resin into the mold, mold the resin, and bury the mesh near the surface of the molded product. This is achieved by a method of manufacturing a resin molded product.

Hereinafter, the present invention will be described in detail. As the resin used in the present invention is not particularly limited as long as injection moldable resin is preferably from the viewpoint of handling properties is a thermoplastic resin, such as acrylic resins, styrene resins, polycarbonate chromatography Bonnet chromatography Resin, ABS resin, olefin resin and the like. Among these thermoplastic resins, acrylic resins in terms of transparency or impact resistance,
Polycarbonate over Bonnet over preparative resin is particularly preferably used.

[0007] The mesh used in the present invention is not particularly limited as long as it has a hole through which the molten resin passes and is not melted or hardly melted by the heat of the molten resin. Examples thereof include nets and fabrics made of metal fibers such as stainless steel fibers and brass fibers, inorganic fibers such as carbon fibers, and synthetic fibers such as polyester fibers and polyamide fibers. If a conductive material is selected from these nets, electromagnetic wave shielding can be achieved.
Can be imparted to the resin molded product, but from the viewpoint of handleability, etc., made of synthetic resin fibers such as polyester fiber and polyamide fiber, and plated, coated, woven fabric to which conductivity is imparted by vapor deposition, etc. In particular, a conductive synthetic fiber fabric such as a conductive polyester cloth or a conductive nylon cloth is preferably used. The pore diameter of the mesh may be any size as long as the molten resin can pass therethrough, and is usually 50 to 50 μm.
1000 mesh, preferably about 100 to 300 mesh is used.

[0008] The resin molded article of the present invention is obtained by burying the above-mentioned net in the vicinity of the surface of the resin molded article. In other words, the net is formed at a desired portion of the resin molded article. Near the surface of, ie, 0.001 to 0.5 mm from the surface of the resin molded product, preferably 0.005 to
It refers to one that is arranged inside by about 0.2 mm. For this reason, in the case of molding using a mold having a smooth mold surface, the mesh material is buried in the vicinity of the surface of the molded article, resulting in a resin molded article having a smooth resin surface. The degree of burying of the mesh in the molded article can be adjusted by the thickness of a film or sheet described later, selection of a material having poor heat conductivity, selection of injection conditions, and the like.

In a preferred embodiment of the method for producing a resin molded product of the present invention, for example, after a film or sheet provided with a mesh is placed in a molding die, the film or sheet is placed from the mesh side. There is a method of injecting a molten resin into a mold to mold the resin and bury the mesh material in the vicinity of the surface of the molded article. Examples of the film or sheet include polyester, polyolefin, nylon, and polyacetate.
A film or sheet of a synthetic resin such as polyester, polycarbonate, polyamide or the like can be used. Among them, a polyethylene terephthalate film or sheet is preferable in terms of handleability and versatility. The thickness of the film or sheet is usually 0.001 to 0.6 mm, preferably 0.01 to 0.6 mm.
Those having a range of 0.1 mm can be used. The method for providing the mesh on the film or sheet is not particularly limited, and the mesh may be spot-bonded to the film or sheet, or an adhesive may be provided between the film or sheet and the mesh. A layer may be provided.

In the above method, after a film or a sheet provided with a mesh is placed in a molding die or the like, the molten resin is injected into the mold from the mesh. In addition to molding the resin, the mesh is buried near the surface of the molded article, but the injection molding conditions differ depending on the type of the mesh or resin, the material of the film or sheet, the shape of the mold, etc. , About mold temperature 4
The temperature ranges from 0 to 180 ° C and the resin temperature ranges from 150 to 450 ° C. For example, when a polyethylene terephthalate film to which a conductive polyester cloth is point-bonded is inserted into a molding die and then an acrylic resin or a polycarbonate resin is injected and molded, a usual metal mold is used. Mold temperature 40-1
This is performed under the temperature conditions of 20 ° C. and a resin temperature of 260 to 360 ° C.

In another preferred embodiment of the method for producing a resin molded product of the present invention, for example, at least one surface of a cavity in which the molded product is molded has a lower heat conductivity than the other surface. Using a molding die composed of a material, after arranging a mesh on the cavity surface with poor thermal conductivity in the mold, injecting a molten resin into the mold, molding the resin, and removing the mesh. A method of burying in the vicinity of the surface of a molded article is exemplified. As the material of the mold used for injection molding,
Normally, steel materials such as carbon steel, chrome molybdenum steel, and stainless steel [having a thermal conductivity of about 15 to 55 W / (m · K)] are used. Examples of the bad material include those having a thermal conductivity of usually 5 W / (m · K) or less, for example, plastics such as epoxy resin [having a thermal conductivity of about 0.1 to 0.5 W / (m · K)] ], Glass / ceramics [Thermal conductivity is 1-3W]
/ (M · K)], ceramic reinforced plastics and the like, and a plastic sheet or the like having a lower thermal conductivity is provided on the commonly used steel material. You may.

In the above method, at least one surface of the cavity in which the molded product is molded is formed of a material having a lower heat conductivity than the other surface. After placing the mesh on the poorly-cavity surface, the molten resin is injected into the mold to mold the resin and to bury the mesh near the surface of the molded article. However, the injection molding conditions vary depending on the type of mesh or resin, the shape of the mold, the material of the mold, and the like.
The range is 0 to 450 ° C. For example, when a conductive polyester cloth is inserted into a molding die provided with a polyethylene terephthalate sheet on a cavity surface, an acrylic resin or a polycarbonate resin is injected and molded. Is usually a mold temperature of 40 to 120 ° C. and a resin temperature of 26.
It is performed under a temperature condition of 0 to 360 ° C.

In the resin molded article of the present invention, since the mesh is buried in the vicinity of the surface of the molded article, it is possible to add a design property to the surface of the molded article and the mesh, and to improve the material of the mesh. Various functions such as electromagnetic shielding can be added.

[0014]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. The injection molding machine used, the mold, the molding material, the molding conditions and the method of measuring the transmitted light intensity ratio are as follows. Injection molding machine: IS-60B (manufactured by Toshiba Machine Co., Ltd.) Die: flat plate type (width 40 mm x length 200 mm x thickness 3)
mm) Molding material: Parapet G-1000, Parapet GF
-1000 (acrylic transparent resin, made by Kuraray) Molding conditions: cylinder temperature 250 ° C, mold temperature 30 ° C,
50 ° C or 90 ° C, injection pressure 85 kg / cm ² , holding pressure 30
kg / cm ² , 50 kg / cm ² or 70 kg / cm ² , cooling time 15 seconds, molding cycle 30 seconds

Measurement method of transmitted light intensity ratio: Using a laser transmitter (HeNe gas laser, wavelength 633 nm, light spot diameter 1 mm) and light power meter (manufactured by Ando Electric), After the laser emitted from the laser transmitter is incident on the measurement sample at right angles, these are arranged so that the transmitted laser is incident on the sensor of the optical power meter. After that, the light intensity of the portion where the mesh is present and the portion where the mesh is not present are measured, and the following equation is obtained from the measured value.

[0016]

## EQU1 ## X = (light intensity of a portion having a mesh / light intensity of a portion having no mesh) × 100

Thus, the transmitted light intensity ratio (X) is calculated.

<Example 1> 39 mm wide x 198 mm long
A polyethylene terephthalate film having a width of 30 mm and a length of 180 mm (commercially available 200 mesh, conductor-deposited product) spotted with an adhesive at approximately the center of a polyethylene terephthalate film having a thickness of 0.25 mm was used. -The insert film was inserted into the mold so that the film was on the side of the cavity of the mold. Using Parapet G-1000 as a molding material, the resin melted into the mold from the conductive polyester cloth side was subjected to the above molding conditions (however, the mold temperature was 50 ° C., and the holding pressure was 50 kg / cm 2).
To produce a molded product. The obtained flat molded product is
The surface is smooth, and when the surface is observed with an optical microscope,
The conductive polyester cloth was completely buried in the resin. The distance between the cloth and the surface of the molded product is approximately 0.01 mm
Met. In addition, 50m from OHP sheet for visibility measurement
The obtained molded product was placed at a distance of m from the printed sheet on the screen so as to block the printed characters, and was projected by OHP to evaluate the visibility of the obtained molded product. The projected printed characters could be confirmed, and the visibility of the obtained molded product was good.

<Embodiment 2> One cavity wall (size: width 40 mm × length 200 mm) of the mold has a thickness of 1 mm.
After the polyethylene terephthalate sheet is adhered, a conductive polyester cloth (commercially available 200 mesh, conductive vapor-deposited product) having a width of 30 mm and a length of 180 mm is further substantially placed at the center of the polyethylene terephthalate sheet. It was scored on tape. Using this molding die, the molten resin was injected into the die under the same molding material and molding conditions as in Example 1 to produce a molded product. The obtained flat molded product had a smooth surface, and the surface was observed with an optical microscope. As a result, the conductive polyester cloth was completely buried in the resin. The distance between the cloth and the surface of the molded product is approximately 0.03.
mm. When the visibility was evaluated in the same manner as in Example 1, the visibility of the molded product obtained in the same manner as in Example 1 was good.

<Comparative Example 1> A molten resin was injected into the mold and molded in the same manner as in Example 1 except that the conductive polyester cloth was directly inserted into the mold without using the polyethylene terephthalate film. The product was manufactured. The surface of the obtained flat molded product was not smooth, and when the surface of the molded product was observed with an optical microscope, the conductive polyester cloth was exposed on the surface of the molded product. When the visibility was evaluated in the same manner as in Example 1, the printed characters were not projected on the screen, and the printed characters could not be confirmed.

<Embodiment 3> 39 mm wide × 198 mm long
A polyethylene terephthalate film having a thickness of 0.25 mm and a conductive nylon cloth having a width of 30 mm and a length of 180 mm (electroless plating of a 200 mesh nylon cloth with a nickel compound) spotted with an adhesive at approximately the center. Was inserted into the mold such that the polyethylene terephthalate film was on the cavity side of the mold. Using Parapet GF-1000 as a molding material, the resin melted in the mold from the conductive nylon cloth side was subjected to the above molding conditions (the mold temperature was 50 ° C. and the dwell pressure was 50 mm).
kg / cm ² ) to produce a molded article. The obtained flat molded product had a smooth surface, and the surface was observed with an optical microscope. As a result, the conductive nylon cloth was completely buried in the resin. The distance between the cloth and the surface of the molded product was approximately 0.01 mm. When the visibility was evaluated in the same manner as in Example 1, the visibility of the obtained molded article was good. The transmitted light intensity ratio was 42%.

<Comparative Examples 2 to 4> In the same manner as in Comparative Example 1, a conductive nylon cloth was directly placed in a mold, and a mold temperature of 30 was used.
° C and the holding pressure were 30 kg / cm ² (Comparative Example 2) and 50, respectively.
kg / cm ² (Comparative Example 3), 70 kg / cm ² (Comparative Example 4)
A molded article was produced in the same manner as in Example 3 except for the above.
The surface of the obtained flat molded product was not smooth, and the surface was observed with an optical microscope. As a result, the conductive nylon cloth was exposed on the surface of the molded product. When the visibility was evaluated in the same manner as in Example 1, the printed characters were not projected on the screen, and the printed characters could not be confirmed. The transmitted light intensity ratios were 7% (Comparative Example 2), 10% (Comparative Example 3),
18% (Comparative Example 4).

<Comparative Examples 5 to 7> In the same manner as in Comparative Example 1, a conductive nylon cloth was directly placed in a mold, and a mold temperature of 90 was used.
° C and the holding pressure were 30 kg / cm ² (Comparative Example 5) and 50, respectively.
kg / cm ² (Comparative Example 6), 70 kg / cm ² (Comparative Example 7)
A molded article was produced in the same manner as in Example 3 except for the above.
The surface of the obtained flat molded product was not smooth, and the surface was observed with an optical microscope. As a result, the conductive nylon cloth was exposed on the surface of the molded product. When the visibility was evaluated in the same manner as in Example 1, the printed characters were not projected on the screen, and the printed characters could not be confirmed. The transmitted light intensity ratios were 33% (Comparative Example 5), 35% (Comparative Example 6), and 36% (Comparative Example 7), respectively.

[0024]

As described above, in the resin molded article of the present invention, since the mesh is buried in the vicinity of the surface of the molded article, it is possible to add a design to the surface of the molded article and the mesh. together, has a characteristic that that Ki out adding also various functionalities by appropriately selecting the material and the like of the net-like product. Further, the resin molded product of the present invention can be easily produced by an injection molding method. For this reason, electromagnetic waves with good visibility? It is possible to supply a resin molded product having designability and functionality, such as a molded product for molding and a resin-reinforced molded product having good surface properties, with high productivity.

Claims (1)

(57) [Claims] 1. A molding die in which at least one surface of a cavity in which a molded article is molded is made of a material having a lower thermal conductivity than the other surface, wherein the thermal conductivity in the mold is poor. A method for producing a resin molded product, comprising: arranging a net on a cavity surface, injecting a molten resin into a mold to mold the resin, and burying the net in the vicinity of the surface of the molded product.