JP3449501B2 - Method of manufacturing conductive resin plate - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of a conductive resin plate having high conductivity which is useful as a radio wave shield, various contacts, antistatic, sheet heating element, and the like. About the method. [0002] Conventionally, as a conductive resin plate, synthetic resin 1
5 Add metal or carbon-based conductivity-imparting filler to
A dispersion of about 100 parts by volume is known. As the conductivity-imparting filler, corrosion resistance and volume resistivity are 10 ⁰
For applications requiring a relatively high resistance of about Ωcm,
Used conductive filler of the carbon-based, 10 ⁰ Ω · cm or less, even more applications where high conductivity of 10 ^-2 Ω · cm order is required, gold, silver, copper, palladium, a metal such as aluminum Made of a conductive additive filler manufactured by Toshiba Corporation .
For the production thereof, a method of kneading using a Banbury mixer, a Henschel mixer, a two-roll mill or the like, followed by forming into a plate by calendering, extrusion or the like has been employed. On the other hand, the present inventors assumed that the corrosion resistance of 10
A process of dissolving a synthetic resin in a solvent to form a synthetic resin solution in order to obtain a conductive resin plate having a high conductivity of ^-2 Ωcm order, and adding a carbon-based conductivity-imparting filler to the synthetic resin solution. A step of dispersing and mixing to obtain a conductive resin solution, a step of applying the conductive resin solution onto a peelable carrier and drying to form a conductive resin layer, and a step of removing the conductive resin layer from the carrier. A method for producing a conductive resin plate, comprising the steps of: peeling to obtain a conductive resin plate. However, when a conductive resin filler formed of a carbon-based material is used in a conductive resin plate formed by the above-described conventional method, air derived from the carbon-based conductive material filler is entrapped. When the true density / bulk density is 5 or more, the tendency is remarkable, and the obtained molded article has a high resistance due to the formation of voids therein. structural destruction of the carbon-based fine particles occurs, the lower limit of the resistance value is increased and so the order of 10 ⁰ Ω · cm as one proceeds. This is the same in calendering, and the air entrainment resistance in the bank portion generated at the corner in the calender roll is increased. On the other hand, in the method according to the present inventors, 10 ^-2 Ω · cm O
Although the resistance value of the hopper is obtained, there are drawbacks such as cost and environmental problems because a large amount of solvent is used. When a metal conductive filler is used, conductivity of the order of 10 ^-2 Ωcm can be obtained, but for applications requiring corrosion resistance, it is necessary to use a noble metal such as gold, platinum, or palladium. Yes, they are very expensive and heavy. An object of the present invention is to provide a method for producing a lightweight and inexpensive conductive resin plate having a high conductivity of the order of 10 ⁻² Ω · cm. SUMMARY OF THE INVENTION The present inventors have found that the reason why the resistance value of a conductive resin plate made of a synthetic resin and a carbon-based conductivity-imparting filler is high, as described above, is that a carbon-based conductive plate has a high conductivity. In the molded product in which the air derived from the property-imparting filler is involved, voids are generated inside and the resistance increases, and when the kneading time is lengthened, the voids decrease, but as the kneading progresses, the structural destruction of the carbon-based fine particles occurs, As a result, the inventors have found that the resistance value increases, and as a result of variously examining a method of reducing the gap without excessive kneading, the present invention has been completed. That is, the production method of the conductive resin plate according to the present invention was obtained <br/> by a carbon-based conductivity-imparting filler and the synthetic resin is true density / bulk density of 5 or more and kneaded within 10 minutes kneading The product is formed into a sheet and then rolled at a temperature above the glass transition point of the synthetic resin and below the melting point.
And a conductive resin with conductivity of the order of 10 ^-2 Ωcm
It is characterized in that a plate is obtained , and in particular, it is preferable that the carbon-based conductive filler has a true density / bulk density of 5 or more, preferably 1,000 or less, more preferably 500 or less. Things. The "melting point" used herein includes "softening temperature" defined by JIS K 7196 or JIS K 7206, for example, those which do not show a sharp melting point like amorphous resins. Hereinafter, the present invention will be described in detail. As the synthetic resin used for the conductive resin plate of the present invention, a conventionally known synthetic resin can be used, and it may be appropriately selected according to its use and purpose. As such a synthetic resin, for example, polycarbonate, phenoxy resin, polyamide,
Polyvinyl chloride, polyvinyl alcohol, polystyrene, polyvinyl acetate, polyvinylidene chloride, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, polyacrylic acid, polymethacrylic acid, polymethyl acrylate, polymethacrylic acid methyl, polyacrylic acid higher esters, polyacrylonitrile, chlorinated polyethylene, chlorosulfonated polyethylene, epichlorohydrin rubber, acrylic rubber, ethylene propylene rubber, ethylene propylene diene rubber, styrene-ethylene-butylene-styrene block copolymer, carboxylated styrene Thermoplastic, thermosetting, preferably thermoplastic, such as ethylene butylene / styrene block copolymers, may be used alone or in combination of two or more. [0006] On the other hand, the flake natural graphite as a carbon filler, amorphous natural graphite, artificial graphite, graphite powder, such as expanded graphite, acetylene black, Ketjen black ^R EC, carbon black such as a conductive oil furnace black alone or A combination of two or more types is mentioned, and in particular, graphite and carbon black are mixed in a ratio of 2: 1 to 1
The ratio is preferably 5: 1 so that a resin having a lower volume resistivity can be obtained when the resin matrix is filled. In this case, the compounding amount of the carbon-based conductivity-imparting filler with respect to the synthetic resin is too small, a desired resistance value cannot be obtained, and if too large, the physical strength of the product is weak. It is preferably 20 to 120 parts by volume, particularly preferably 30 to 100 parts by volume. These carbon-based conductivity-imparting fillers are directly kneaded into a synthetic resin to obtain a conductive resin composition. As a method for obtaining a conductive resin composition, there are two rolls with a heating device, a Banbury mixer, a pressurized kneader, a Henschel mixer, a co-kneader (biaxial Extruder) and the like. The conductive resin used for the conductive resin plate of the present invention may further contain various additives such as a processing aid, a reinforcing agent, a heat stabilizer, a light stabilizer, and an antioxidant. [0007] The conductive resin composition thus obtained is formed into a sheet by calendering, extrusion T
Die forming, dispensing with two rolls, and the like are exemplified.
Next, the sheet-shaped conductive resin is rolled using a roll. The speed ratio of the rolls at this time is preferably set to 1: 1. May have a speed difference of about 1: 1.2,
Exceeding this is not preferred because the rolled product is apt to wrinkle. The roll temperature must be equal to or higher than the glass transition point of the used synthetic resin and equal to or lower than the melting point. Below the glass transition point, cracks occur. Above the melting point, peeling from the roll is poor, and in any case, rolling becomes difficult. . Rolling efficiency can be increased by previously heating the sheet-shaped conductive resin to a temperature similar to that of a roll. By giving a temperature difference between the rolls, the rolled sheet can be made to follow one of the rolls. [0008] Rather than producing a thin sheet from the beginning and obtaining a desired thickness by one rolling, the first sheet is made thicker and passed through a plurality of rolls to obtain a desired thickness. The amount can be increased, and a conductive resin plate having a lower resistance value can be obtained. Specifically, the thickness after rolling is preferably ２ or less, particularly preferably と or less with respect to the initial thickness. A desired thickness may be obtained from one rolled sheet. However, if a desired thickness is obtained by combining a plurality of sheets, the rolling amount can be further increased, and the resistance value can be further increased. A low conductive resin plate can be obtained. Examples of a method of combining and integrating a plurality of sheets include a method in which the sheets are stacked to be thicker than a desired thickness, passed between rolls, and a method using a press. The present invention is based on the manufacturing method as described above. However, since the degree of kneading greatly affects the resistance value of the finally obtained conductive resin plate, the effect on the resistance value by the kneading device is confirmed. It is important that the kneading be completed within 10 minutes, especially 5 minutes after the total amount of the carbon-based conductivity-imparting filler is charged, thereby preventing structural destruction and maintaining a low resistance value. When using a carbon-based conductivity-imparting filler, it is preferable that the structure is easily formed in order to obtain higher conductivity. Therefore, those having a true density / bulk density of 5 or more are preferred.
It is particularly useful. In addition, true density / bulk density is 1000
If it is larger, it is difficult to mix and workability is likely to be poor. In the present invention, after the conductive resin composition is formed into a sheet, a rolling process is performed to reduce the gaps caused by the entrainment of air derived from the carbon-based conductivity- imparting filler. And a conductive resin plate having a low resistance value can be obtained. Further, since a carbon-based filler is used as the conductivity-imparting filler, an inexpensive and lightweight conductive resin plate can be obtained. EXAMPLES (Example 1) Chlorinated polyethylene having a chlorination degree of 40%: Eraslen 401A
3 parts by weight of β-aminocrotonate (manufactured by Showa Chemical Industry Co., Ltd.) as a stabilizer were added to 100 parts by weight (manufactured by Showa Denko KK, trade name, Tg point −15 ° C., melting point [softening point] 140 ° C.)
Dry up with a Henschel mixer. Expanded graphite BSP-50 (manufactured by Chuetsu Graphite Industry Co., Ltd., trade name, true density)
2.2 g / cm ³ , bulk density 0.2 g / cm ³ ) 112.5 parts by weight and carbon black: Ketchen Black EC (manufactured by Lion, trade name, true density 1.9 g / cm ³ , bulk density 0.15 g / cm ³ ) 37.5 And kneaded at 100 ° C. for 5 minutes with a pressure kneader to obtain a conductive resin composition. Since this composition had a high content of the conductivity-imparting filler, it was not a lump but a granular. The conductive resin composition was dispensed using two rolls and formed into a sheet having a thickness of 1.5 mm, a width of 400 mm, and a length of 600 mm. Next, this sheet-shaped conductive resin composition was
Heat to 0 ° C and apply 200kgf linear pressure between 14 inch rolls at 100 ° C
It was rolled three times at a speed of 1.5 m / min at a speed of 1.5 m / min and rolled to a thickness of 0.5 mm. Finally, two pieces of the obtained product were put on each other, and 170 ° C, 7
0 kgf / cm ² after heat pressing 10 min, 30 ° C. while under pressure
This was cooled to obtain a conductive resin plate having a thickness of 1.0 mm. When this volume specific resistance was measured using Loresta AP MCP-T400 (trade name, manufactured by Mitsubishi Yuka), it was 1.4 la 10 ^-2 Ω · cm. Comparative Example 1 In Example 1, scaly graphite was used instead of expanded graphite BSP-50.
BF-50A (manufactured by Chuetsu Graphite Industries, trade name, true density 2.2 g / cm ³ ,
A conductive resin plate having a thickness of 1.0 mm was obtained in the same manner except that the bulk density was 0.6 g / cm ³ ) and 112.5 parts by weight were used. The volume resistivity was measured using a Loresta AP · MCP-T400 (supra), was 3.5 La 10 ⁰ Ω · cm. According to the present invention, a conductive resin plate having high conductivity on the order of 10 ⁻² Ω · cm can be obtained at a low weight and at a low cost.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI B29K 507: 04 B29K 507: 04 (56) References JP-A-4-275127 (JP, A) JP-A-59-196224 (JP) , A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01B 1/24 B29C 43/00-43/58

Claims (1)

(57) Patent Claims 1. A true density / bulk density of 5 or more in a carbon-based conductivity-imparting filler and a synthetic resin and a sheet of the kneaded product obtained by kneading within 10 minutes A method for producing a conductive resin plate, characterized in that the conductive resin plate is formed by rolling at a temperature not lower than the glass transition point of the synthetic resin and not higher than the melting point, and has a conductivity of the order of 10 ^-2 Ω · cm .