JP2005081827A - Anti-static resin molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an anti-static resin molding having a surface resistivity of 10<SP>12</SP>Ω/cm<SP>2</SP>or higher, which can be used for housings of electric/electronic parts and apparatuses, molded parts of resins, transporting containers for electric/electronic parts and apparatuses, and the like. <P>SOLUTION: The anti-static resin molding is produced by injection molding, and on the whole surface of a substrate made of a thermoplastic resin is formed a layer composed of an anti-static resin molding having a melting point of 150°C or higher and a surface resistivity of 10<SP>6</SP>-10<SP>12</SP>Ω/cm<SP>2</SP>under standard condition. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  Thermoplastic resins, which are general-purpose resins, are used in various fields, but usually have electrical insulating properties and are easily charged with static electricity. For this reason, there is a problem that foreign matters are likely to adhere to the molded product, and the electrical characteristics of the device are disturbed by static electricity. For example, it is transported in a container such as a carrier tape, magazine, tray, or bag as a storage container that stores electronic components such as IC components, LEDs, and wiring boards. During transport, a short circuit occurs between the storage container and the interior component side (ESD), resulting in a decrease in workability when mounting electronic components. Furthermore, static electricity is short-circuited between finely structured wirings, which causes the quality to deteriorate. Therefore, the storage container is required to have electrical conductivity and antistatic properties so as not to have an influence of static electricity on electronic devices and components. In recent years, especially with the high integration of integrated circuits, circuits have been miniaturized, and the importance of antistatic is increasing.

  In order to prevent such an electrostatic charge, a metal powder, metal oxide powder, carbon black, carbon fiber, or the like is kneaded to impart conductivity (for example, Patent Document 1), or applied to impart antistatic properties. There exists a method of using a thing (for example, patent document 2) as a packaging container.

  In addition, a conductive substance is used as a substance having an antistatic effect, and the packaging container is partially short-circuited or shielded by interposing it in a film layer on the inner surface, outer surface of the packaging container or the packaging container itself, thereby partially charging the packaging container. A technique for preventing this is disclosed (for example, Patent Document 3). Further, a packaging body is disclosed in which an antistatic sheet in which a resin having a good antistatic property is laminated is incorporated in the packaging container, and the contents are protected from impact during transportation and the trouble of static electricity is suppressed (for example, Patent Document 4).

  However, when an antistatic material is kneaded for antistatic purposes, these fillers must be kneaded into a resin to form pellets, and then melted and injection molded. In addition, the characteristics of the resin to be kneaded affect the entire container.

  In addition, when a conductive substance is interposed in the container as an antistatic substance or when an electrode for discharging is provided, a process of manufacturing these, a process of separately preparing such a material, and a process of combining with a container member Need.

  Furthermore, in the case where the antistatic sheet is contained in the container, this sheet forming process is performed separately from the container forming process, and when the electronic component is stored, a process of incorporating it in the container at the same time as the component must be passed. Don't be.

  Further, in resin injection molding, there is a problem in handling defective products occurring before and after mold replacement, and unnecessary resin accumulated in nozzles in the cold runner method. These are usually reused as the resin raw material to be used. However, since they contain impurities, a large blending ratio leads to a decrease in product quality. For this reason, the blending ratio is limited to a certain ratio or less, and much must be discarded.

  However, in recent years, official regulations have been imposed on the disposal of waste, which necessitates a detoxification process at the time of disposal, which increases costs.

Japanese Patent No. 3283831 Japanese Patent No. 2541637 Japanese Patent Laid-Open No. 1983376 JP 2003-236916 A

  There is a demand for an application in which waste resin generated during resin molding can be used without being discarded. On the other hand, a method for economically obtaining a packaging container having an antistatic effect in a packaging container for packing and transporting electronic components has been awaited.

  In view of the above, the present inventor has conducted earnest research with the aim of developing a packaging container made of an antistatic resin molded product that can withstand use as a packaging container for electronic components while using various resins including waste resin. The present invention has been repeated.

An embodiment of the resin molded product according to the present invention is a resin molded product by injection molding, and the entire surface of a base material made of a thermoplastic resin has a melting temperature of 150 ° C. or higher and a surface resistivity of standard. It has a structure in which a layer made of an antistatic resin that is 10 ⁶ to 10 ¹² Ω / cm ² in the state is formed.

  The antistatic resin molding according to the present invention can be molded in one cycle by injecting the thermoplastic resin and antistatic resin into a single mold by a sandwich molding machine.

Furthermore, the antistatic resin molding according to the present invention has a surface resistivity of 10 ¹² Ω / cm ² or less in a standard state.

  Here, the antistatic resin can be made of a resin composition containing a polyvinyl alcohol-based resin as a main component. Further, a resin composition containing a vinyl acetate-vinyl alcohol copolymer derivative as a main component can be used as a main component.

  The antistatic resin molded product of the present invention can be used in a storage container for transporting electronic / electrical parts.

  Or the antistatic resin molding of this invention can be used for the housing of an electric / electronic device. Alternatively, it can be used as a structure of electric / electronic parts.

  The antistatic resin molding according to the present invention has a configuration in which an antistatic resin layer is formed on the entire surface of a base material made of a thermoplastic resin, and a container molded using this has, for example, a fine wiring structure. As a packaging container for packing and transporting electronic components such as semiconductor devices, wiring boards, and LEDs, it is possible to prevent the generation of static electricity due to friction between containers or between the container and the electronic components.

Since the resin molded product of the present invention has an antistatic property that the surface resistivity is 10 ¹² Ω / cm ² or less in a standard state, when this is used for a housing or a storage container of an electric / electronic device, electrostatic induction Can prevent electrostatic breakdown.

  The resin molded product of the present invention can be manufactured from a raw material resin by sandwich molding, using a single mold in one step, and a surface layer is formed on the molded product, which is a manufacturing process for other members that has been conventionally required. Since other steps such as a coating step are not required, it can be manufactured at low cost.

The resin molded product of the present invention forms a surface layer using an antistatic resin having a melting temperature of 150 ° C. or higher and a surface resistivity of 10 ⁶ to 10 ¹² Ω / cm ² in a standard state. In addition, it has an excellent anti-static effect on resin molded products. This is obtained by using an antistatic resin, preferably a polyvinyl alcohol-based resin, particularly a resin made of a vinyl acetate-vinyl alcohol copolymer as a main component. Further, the antistatic resin can have a certain hygroscopic property. For this reason, it has a humidity control effect. When storing and storing electrical and electronic equipment, the effect of the external environment, especially normal humidity, increases the antistatic property along with the moisture retention phenomenon and realizes low surface resistivity. To do.

  In the resin molded product of the present invention, any resin can be used as the thermoplastic resin as a base material used therein as long as the resin has mechanical strength that can withstand resin molding. Furthermore, it is possible to use a resin containing impurities that had to be discarded and having deteriorated physical properties, a recycled resin from a discarded plastic, or the like. For this reason, the resin molding which is comparatively cheap and has the outstanding antistatic property can be obtained.

  Hereinafter, the resin molded product of the present invention will be described together with the production method.

  The packaging container of the present invention is injection-molded using a die having a shape that matches the shape of the electronic component that is housed therein and conveyed. For this reason, various shapes can be selected, but the cross section basically has a three-layer structure. A thermoplastic resin is used as a base material, and a layer made of an antistatic resin is arranged on the entire surface with a constant thickness. FIG. 1 shows a schematic cross-sectional view of a resin molded product 10 of the present invention. In this structure, the antistatic resin 14 is coated on the entire surface of the thermoplastic resin 12 serving as a base material.

  Various general-purpose thermoplastic resins can be used as the thermoplastic resin 12 used as the base material of the resin molded product of the present invention as long as the moldability by injection molding can be basically maintained. For example, polypropylene, polyethylene, polyacrylate, polymethacrylate, polystyrene, poly-p-xylylene, polyvinyl acetate, polyacrylonitrile, acrylonitrile / styrene resin, acrylonitrile / butadiene / styrene resin, polyvinyl resin, vinylidene chloride, polyethylene terephthalate, poly Examples include butylene terephthalate, polyamide resin, polycarbonate, fluorine plastic, polyvinyl ether, polyvinyl ketone, polyether, thermoplastic polyester, polyamide, and polyurethane plastic. In the processing steps of these resins, resins whose quality is deteriorated due to mixing of impurities, variations in polymerization degree, and the like, and recycled resins of plastic waste can be used as long as the mechanical strength can be maintained.

The antistatic resin 14 for covering the entire surface of the thermoplastic resin used in the resin molded product of the present invention is variously selected in the range where the surface resistivity is 10 ⁶ to 10 ¹² Ω / cm ² in the standard state. Yes. If the surface resistivity is within this range, it is difficult to be charged, and even if it is charged with static electricity, it has a characteristic of being easily diffused.

If the surface resistivity is less than 10 ⁶ Ω / cm ² in the standard state, the electrical conductivity is good, so if charges are accumulated on the electronic component side, discharge may occur on the inner surface side of the container. On the other hand, if it exceeds 10 ¹² Ω / cm ² , the antistatic effect is reduced, and high static electricity is charged on the inner surface of the container, which may cause discharge to the internal product.

In addition, the antistatic resin 14 used in the present invention is resistant to injection molding in the relationship with the thermoplastic resin that is the base material of the antistatic resin molded product of the present invention. From the viewpoint of securing adhesiveness, the melting temperature is preferably 150 ° C. or higher. If the temperature is lower than this temperature, the adhesiveness to the surface of the thermoplastic resin may not be ensured, and if it exceeds 220 ° C., it may be decomposed in the injection molding machine to deteriorate the performance.

  Examples of the antistatic resin having the above-described characteristics include olefinic resins or derivatives thereof, cyclic olefins, polystyrene and derivatives thereof, and hydrophilic groups such as hydroxyl groups, ether groups, amino groups such as vinyl resins and polyamide resins. And a resin composition containing a derivative thereof. Preferably, a resin composition containing a polyvinyl alcohol-based resin, particularly a resin composition containing a vinyl acetate-vinyl alcohol copolymer derivative is preferred. Those imparted with mechanical strength, electrical characteristics, and fluidity by adjusting the degree of saponification or the degree of polymerization or introducing other organic groups are preferably used.

  By adjusting the degree of saponification, moisture absorption can be imparted in addition to the antistatic property, and the electrical characteristics of the electric / electronic device can be maintained without being affected by the external environment depending on the usage environment. It may be produced by a method in which monomers are mixed and polymerized to produce a block copolymer, or a method in which an acetyl group is substituted with a hydroxyl group by saponifying a vinyl acetate polymer after production. Also, other organic groups are added to the vinyl acetate-vinyl alcohol copolymer and / or polymer alloy, for example, a compatible polymer blend with other thermoplastic resin, block copolymer or graft copolymer, etc. Thus, suitable characteristics can be imparted to the resin molded product of the present invention.

  Additives such as plasticizers, stabilizers, compatibilizers, etc. to the above resins, in addition to antistatic properties, mechanical properties, flexibility, etc., improvement of adhesion to thermoplastic resin as the base material, etc. Various characteristics may be added. Furthermore, it can also color by adding an inorganic pigment and an organic pigment.

  The compatibilizing agent is appropriately selected depending on the individual combination so that the viscosity of the antistatic resin composition is adjusted and the combination of the thermoplastic resin used as the base material and the antistatic resin has good adhesion. Can be used. Examples thereof include copolymers such as styrene butadiene rubber, silicon-modified epoxy resin, and polyolefin resin.

  The resin molded product according to the present invention can be obtained by connecting a sandwich molding machine and a mold that can be molded into a desired shape, and injection molding the two kinds of resins. Specifically, the thermoplastic resin as the base material, antistatic resin pellets, powders, particulate solids and a hopper are installed in the hopper and melted through the nozzle of the flow path in another path. To introduce. At this time, the antistatic resin is first injected into the mold, and then switched to the thermoplastic resin to be the base material. By controlling the timing of this injection and the melting temperature, mold temperature, melt viscosity, etc., the two types of resins introduced into the mold have the entire surface of the thermoplastic resin as the base material in the molded product. The entire surface is covered with antistatic resin with a certain thickness, and the entire surface is a resin molded product having antistatic properties.

  The resin molded product of the present invention can be manufactured by one step of an injection molding process using one mold as described above. In addition, when the nozzle for introducing the resin is switched from the antistatic resin to the thermoplastic resin, the antistatic resin remaining in the nozzle without reaching the mold is mixed into the thermoplastic resin to be discharged afterwards, and is transferred to the mold. By being introduced, the antistatic resin covers the surface as a part of the base material and is encapsulated in the resin molded product. Therefore, it is not necessary to remove the resin remaining in the nozzle, and the material can be used without waste.

  The thickness of the antistatic resin can be appropriately selected by setting the conditions of the molding machine. It is also possible to form a thickness of 0.5 mm or less. From the viewpoint of maintaining antistatic properties over time, about 0.5 mm is preferable. When applying a coating film with antistatic effect, since the film is thin, the antistatic effect may deteriorate over time, and the process and equipment that require multiple applications will be complicated. The resin molding by sandwich molding of the invention can form an antistatic layer having a certain thickness in one step.

Thus, the obtained antistatic resin molding of the present invention has a surface resistivity of 10 ¹² Ω / cm ² or less in a standard state, and has an excellent antistatic effect.

  Embodiments based on the present invention will be described below. In Examples, a double injection FN4000-25AD manufactured by Nissei Plastic Industry was used as an injection molding machine, a disk-shaped mold having a thickness of 3 mm and a diameter of 120 mm was sandwich-molded, and a sample was collected.

  The surface resistivity was measured using a Hirester-UP MCP-HT450 manufactured by Mitsubishi Chemical, and the measurement probe was a constant temperature chamber (20 ° C. relative humidity 60%) using a URS probe RMH214.

  HDPE (manufactured by Asahi Kasei Corporation) was used as the thermoplastic resin for the internal substrate. As the antistatic resin, modified polyvinyl alcohol resin A (manufactured by Kuraray Co., Ltd.) was used. A sandwich molding machine was used. It was operated at a cylinder internal temperature of 160 ° C. to 200 ° C. and injected into a die held at a mold temperature of 20 ° C. to produce a disk-shaped resin molded product having a diameter of 12 cm and a thickness of 3 mm. The average thickness of the antistatic resin forming the surface was 0.5 mm. The surface resistivity of the molded product was measured. The results are shown in Table 1.

  A resin molded product was prepared in the same manner as in Example 1 except that modified polyvinyl alcohol resin B (manufactured by Kuraray Co., Ltd.) was used as the antistatic resin. About the manufactured molded article, the surface resistivity was measured. The results are shown in Table 1.

[Reference Examples 1 and 2]
About modified polyvinyl alcohol-type resin A and B (made by Kuraray Co., Ltd.), it carried out similarly to Example 1, and manufactured the resin molded product. For these, the surface resistivity was measured. The results are shown in Table 1.

[Comparative Example 1]
Using HDPE (manufactured by Asahi Kasei Co., Ltd.) used in Example 1, molding was performed in the same manner as in Example 1. The surface resistivity was measured. The results are shown in Table 1.

The antistatic resin molded product according to the present invention has a good antistatic effect, and is suitably used as a housing for electrical and electronic equipment, a container for transporting and storing electronic components, and the like. In addition, since there is almost no decrease in the antistatic effect due to washing or aging, it can withstand repeated use. Furthermore, the thermoplastic resin used as the base material can be variously selected as long as it has mechanical strength, and a high-quality, high-functional resin molded product can be obtained inexpensively and easily.

It is a cross-sectional schematic diagram of one example of the resin molded product concerning this invention.

Explanation of symbols

10; Resin molded product according to the present invention 12; Thermoplastic resin 14; Antistatic resin

Claims (8)

A resin molded product by injection molding, having a melting temperature of 150 ° C. or higher and a surface resistivity of 10 ⁶ to 10 ¹² Ω / cm ² in a standard state over the entire surface of a base material made of a thermoplastic resin. An antistatic resin molded article in which a layer made of an antistatic resin is formed. The antistatic resin molded article according to claim 1, wherein the thermoplastic resin and the antistatic resin are injected into one mold by a sandwich molding machine and two-color molding is performed by one clamping. The antistatic resin molded product according to claim 1, wherein the surface resistivity is 10 ¹² Ω / cm ² or less in a standard state. The antistatic resin molded product according to any one of claims 1 to 3, wherein the antistatic resin is made of a resin composition containing a vinyl alcohol polymer as a main component. The antistatic resin molded product according to claim 4, wherein the antistatic resin contains a resin composed of a vinyl acetate-vinyl alcohol copolymer derivative as a main component. The antistatic resin molded product according to any one of claims 1 to 5, which is used in a storage container for transporting electronic / electrical parts. The antistatic resin molded product according to any one of claims 1 to 5, which is used for a housing of an electric / electronic device. The antistatic resin molded product according to any one of claims 1 to 5, which is used for a resin molded portion of an electric / electronic component.

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