JP2002067209A - Conductive plastic sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive plastic sheet having sufficient conductivity for antistatic properties and further having a thermally stable surface specific resistance value. SOLUTION: The conductive plastic sheet comprises a conductive resin composition obtained by blending a polyester resin, a carbon nanotube and a solvent of 27:23:50 by weight and uniformly formed in a thickness of 30 μm on one side surface of a polystyrene resin sheet having a thickness of 0.3 mm. As a result of measuring a surface specific resistance of the surface molded with the composition, the specific resistance is 106 Ω with sufficient antistatic properties. Further, when the surface specific resistance of the plastic sheet is measured after the plastic sheet is held at 80 deg.C for 20 hours, the resistance is 106 Ωwhich is not changed with sufficient thermal stability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a conductive plastic sheet used for carrier tapes, trays and the like used for transporting, storing and mounting electronic components such as ICs and transistors.

[0002]

2. Description of the Related Art In recent years, with the remarkable progress of surface mounting technology in the production of electronic components, demand for high-performance and small-sized electronic components, particularly small-sized chip-type electronic components has been rapidly increasing. The chip-type electronic components include an IC, a transistor, a diode, and the like, which are stored in a carrier tape or a tray, transported, and stored.

[0003] For example, in the case of a carrier tape, it is supplied as a package sealed with a top tape serving as a lid material. The assembling of this chip-type electronic component into an electronic circuit is performed by sequentially sending out the package. In this method, a top tape is peeled off from a carrier tape, chip-type electronic components are automatically picked up, and are automatically mounted at predetermined positions on a circuit board.

[0004] However, in the transport and mounting steps, the carrier tape is charged by static electricity due to friction and static electricity generated in the step of peeling off the top tape. Due to the charging of this carrier tape,
There are problems that it is difficult to accurately mount the chip-type electronic component at a predetermined position, and that electrostatic breakdown occurs. Therefore, it is necessary to impart conductivity to this package to prevent accumulation of static electricity.

[0005] In order to impart conductivity to the carrier tape, a conductive polystyrene obtained by kneading a large amount of carbon black as a conductive filler into a polystyrene resin on the front and back sides of a base sheet made of a polystyrene resin as a resin composition. A conductive plastic sheet formed by integrally laminating a resin composition and a base sheet by coextrusion is produced by secondary processing such as press molding or vacuum molding.

[0006]

In such a carrier sheet, carbon black has poor thermal stability, and when subjected to high-temperature treatment during an integral lamination process with a base sheet or during secondary processing, the carbon black itself does not have a high thermal stability. The resistance value changes, and as a result, the specific resistance value of the conductive plastic sheet surface does not reach a predetermined value, and the resistance value becomes too large to obtain sufficient conductivity or the resistance value becomes small. This causes a problem that the terminals of the electronic component that come into contact with the surface of the conductive composition are conductive and shorts occur.

[0007] The present invention has been made to solve the above problem, and has as its object to provide a conductive plastic sheet which is not affected by static electricity and is thermally stable.

[0008]

Means for Solving the Problems To solve the above problems, the conductive plastic sheet of the present invention is based on a conductive resin composition containing carbon nanotubes on one or both sides of a base sheet made of the resin composition. The conductive composition has a surface specific resistance of 10 ⁴ Ω to 10 ⁸ Ω.

The resin used for the conductive resin composition is not particularly limited, but one or a blend of two or more selected from polystyrene resins, polyester resins, polyolefin resins and polyvinyl chloride resins is used. You. In addition, various additives such as stabilizers, lubricants, antioxidants, and ultraviolet absorbers can be added to these resins as needed, as long as the basic performance such as strength and moldability is not impaired. .

The base sheet manufactured using the above resin may be a single layer sheet made of a single resin or a multilayer sheet obtained by laminating two or more kinds of resins. Although there is no particular limitation on the method for producing the base sheet, a general method such as a T-die extrusion method and a calendar method is used. The method of laminating the multilayer sheet is a multilayer die that is melt-extruded by several extruders, a co-extrusion method in which the sheet is guided by a field block, or a single-layer sheet or film that forms each layer using an appropriate adhesive. Dry nomination method or the like is used.

In the conductive plastic sheet of the present invention, a conductive resin composition containing carbon nanotubes on one or both sides is formed integrally with a base sheet. The main component is a nanotube and a solvent. As the resin component, an acrylic resin, a polyester resin, a polyurethane resin, or the like is used. As the solvent, ester type, alcohol type,
Hydrocarbons are used. Ethyl acetate, butyl acetate and the like are used as the ester type, methanol and ethanol are used as the alcohol type, and toluene, xylene and the like are used as the hydrocarbon type. The contents of the various components are not particularly limited, but the resin content is 5 to 50% by weight, the carbon nanotubes are 5 to 45% by weight, and the solvent is 3 to 5% by weight.
0 to 80% by weight is suitable. In addition to these main components, a dispersant, a plasticizer, and the like may be appropriately used as additives in the conductive composition. Further, the thickness of the conductive plastic sheet is 0.1 to 0.8 mm, more preferably 0.25 to 0.8 mm, in order to obtain sufficient strength and good moldability during secondary processing.
A range of 0.55 mm is appropriate.

As the method for molding the conductive composition of the present invention on the surface of a substrate sheet, methods such as a gravure coating method, a dip coating method, and a roll coating method can be used. The surface resistivity of the carbon nanotube-containing conductive composition is suitably from 10 ⁴ to 10 ⁸ Ω. If the surface specific resistance value is less than 10 ⁴ Ω, there is a risk that the terminals of the electronic components that come into contact with the surface of the conductive composition will conduct and shorts. If it is 10 ⁸ Ω or more, sufficient conductivity cannot be obtained.
Static electricity is easily generated, and the object of the present invention cannot be achieved.

[0013]

Embodiments of the present invention will be described below in detail. Carbon nanotubes were produced by the following method (catalytic hydrogen reduction of carbon dioxide).

Flow type fixed bed reactor (diameter 8 cm, length 3
0 cm) was charged with 300 g of a catalyst (50 w% Ni / SiO ₂ ), reduced with hydrogen (1 L / min.) At 400 ° C. for 1 hour, and then reacted with 7.5 L / min. (H ₂ : CO ₂ =
2: 1 v / v) and react at 500 ° C. for 4 hours. After the reaction, the inside of the reactor was replaced with nitrogen gas. The reactor was cooled to room temperature, and the catalyst in the reactor was observed with a scanning electron microscope. As a result, formation of carbon nanotubes on the catalyst surface was confirmed. Note that the carbon nanotubes may be manufactured by a general manufacturing method such as an arc discharge method, a laser evaporation method, or a thermal decomposition method.

As a conductive resin composition, a polyester resin, carbon nanotubes obtained by the above method and a solvent (a mixed solvent of toluene / ethyl acetate) were mixed at a weight ratio of 27:23:50 and dispersed. After appropriately adding additives such as an agent, a plasticizer, an antioxidant, and an ultraviolet absorber, the mixture was mixed by a ball mill for 40 minutes to prepare a mixture. As the solvent, ketone solvents such as acetone, ester solvents such as ethyl acetate, aromatic solvents such as toluene,
Alcohol solvents such as methanol may be used alone or in combination of two or more. As the additive, commonly used known ones can be appropriately used according to the purpose.

Next, a first embodiment of the conductive plastic sheet of the present invention will be described. Using a polystyrene resin as the base sheet, a 0.3 mm thick polystyrene sheet having both surfaces of the sheet being mirror surfaces was prepared by a T-die extrusion method. Next, the conductive resin composition containing the carbon nanotubes was formed on one surface of a polystyrene resin base sheet to a thickness of 30 μm by a gravure coating method to prepare a conductive plastic sheet. Among the prepared conductive plastic sheets, the surface specific resistance of the surface on which the conductive composition was molded was measured by the method specified in JIS-K-6911, and as a result, was 10 ⁶ Ω.

The conductive plastic sheet is placed in a thermostat and heated to 80 ° C. at a rate of 1 ° C./min.
In after 20 hours, was measured the surface resistivity of the surface which is molded a conductive composition was taken out to room temperature, 10 ⁶
Ω and there was no change. Further, the conductive plastic sheet is directly put into a constant temperature bath heated to 80 ° C., kept at 80 ° C. for 20 hours, taken out at room temperature, and measured for the surface resistivity of the surface on which the conductive composition was molded. As a result, it was 10 ⁶ Ω, and there was no change.

Next, a second embodiment of the plastic sheet of the present invention will be described. A polyester resin was used as a base sheet, and a 0.5 mm-thick polyester in which both surfaces of the sheet were mirror surfaces was prepared by a T-die extrusion method. next,
The conductive resin composition containing the carbon nanotubes was formed on both surfaces of a polyester resin base sheet to a thickness of 30 μm by a gravure coating method to prepare a conductive plastic sheet. As a result of measuring the surface resistivity of both sides of the produced conductive plastic sheet, 10
⁶ Ω.

[0019] Put the conductive plastic sheet in a constant temperature bath heated to 80 ° C., was held at 80 ° C. 20 hours, was measured the surface resistivity of the double-sided taken out into room temperature, either 10 ⁶ Omega There was no change.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments, and various changes may be made within the scope of the present invention described in the appended claims. be able to. For example, the thickness of the conductive resin composition containing carbon nanotubes formed on the surface of the base material sheet is not limited to the above examples, and a uniform film can be formed, and the moldability during the secondary processing is improved. It can be selected within a range that does not adversely affect.

The conductive plastic sheet of the present invention is
Since the conductive resin composition containing carbon nanotubes is formed as a conductive layer on the surface of the resin substrate sheet, and the surface specific resistance of the conductive layer is controlled in the range of 10 ⁴ to 10 ⁸ , sufficient antistatic properties are provided. It has properties and thermal stability. A conductive plastic sheet having such characteristics is most suitable for carrier tapes and trays used for transporting, storing, and mounting electronic components.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 5/24 C09D 5/24 7/12 7/12 201/00 201/00 H01B 5/14 H01B 5 / 14 Z H01L 23/00 H01L 23/00 Z // C08L 101: 00 C08L 101: 00 F term (reference) 4D075 CA22 DA04 DB31 DC19 EA02 EA06 EC01 EC22 4F006 AA12 AA15 AA17 AB24 AB35 AB37 AB72 CA08 4F100 AA37B AK01A AK01BAKA BA02 GB41 JG01B JG03 JG04B JJ03 YY00B 4J038 DD001 HA026 KA12 KA21 NA14 NA20 PC08 5G307 GA02 GC02

Claims (1)

[Claims] 1. A conductive layer comprising a conductive resin composition containing carbon nanotubes and having a surface specific resistance in a range of 10 ⁴ to 10 ⁸ Ω is provided on at least one surface of a resin base sheet. Conductive plastic sheet.