JPH0342304B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention has electrical conductivity, flexibility, high temperature compression set,
The present invention relates to a conductive polymer composition that has excellent mechanical strength and has a high moldability equivalent to that of ordinary thermoplastic resins. In recent years, conductive rubber, which is made by blending carbon black with rubber to impart conductivity, has been used for purposes such as antistatic purposes in fields such as electronic equipment and electric wires. With the advancement of electronics,
Demand for conductive materials with rubber-like physical properties is becoming increasingly sophisticated, and themes that require a high level of moldability that allows products with complex shapes to be formed using the same molding method as ordinary thermoplastic resins. has increased significantly. Conventional conductive rubber requires a vulcanization process, so it can only be applied to molding methods such as compression molding, which have low productivity and cannot produce products with complex shapes. The reality was that this was not possible. The inventors of the present invention have made extensive studies in light of these circumstances, and have found that a large amount of non-aromatic rubber softeners, α-olefin polymers and carbon based on hydrogenated derivatives of styrene/conjugated diene block copolymers have been developed. With the composition containing black,
We succeeded in obtaining a conductive polymer composition that has the desired properties of conductivity, flexibility, high-temperature compression set, and mechanical strength, and also has high moldability comparable to that of ordinary thermoplastic resins. That is, the present invention is a conductive polymer composition characterized by comprising the following (a) to (d). (a) General formula A(-B-A)n (where A is a monovinyl-substituted aromatic hydrocarbon polymer block, B is a conjugated diene elastomeric polymer block, and n is an integer from 1 to 5. 100 parts by weight of a hydrogenated derivative of a copolymer represented by (b) 180 to 500 parts by weight of a softener for non-aromatic rubber (c) 30 to 500 parts by weight of an isotactic propylene homopolymer
400 parts by weight (d) 50 to 500 parts by weight of conductive carbon black (a) Component (a) used in the present invention has a general formula of A(-B
-A) It is a hydrogenated derivative obtained by hydrogenating a block copolymer represented by n, and in the above general formula, A is a polymer block of monovinyl-substituted aromatic hydrocarbon, and B is an elastomer of a conjugated diene. It is a polymer block, and n is an integer from 1 to 5. The monovinyl-substituted aromatic hydrocarbon monomer constituting the polymer block A is preferably styrene, and α-methylstyrene or the like may also be used. The conjugated diene monomer in polymer block B is preferably butadiene or isoprene, or may be a mixture of the two. When butadiene is used as the single conjugated diene monomer to form polymer block B, the block copolymer retains its elastomeric properties after being hydrogenated to saturate the double bonds. In order to achieve this, it is preferable to adopt polymerization conditions such that the 1,2-microstructure accounts for 20 to 50% of the microstructure in the polybutadiene block, and more preferably, the 1,2-microstructure accounts for 35 to 50% of the microstructure in the polybutadiene block.
45%. The weight average molecular weight of polymer block A in the block copolymer is 5,000 to 125,000, and that of block B is 15,000.
It is preferably in the range of ~250,000. Many methods have been proposed for producing these block copolymers, but a typical method is, for example, the method described in Japanese Patent Publication No. 40-23798, using a lithium catalyst or Ziegler type. It can be obtained by block polymerization in an inert solvent using a catalyst. The hydrogenation treatment of these block copolymers is
For example, hydrogenation is carried out in the presence of a hydrogenation catalyst in an inert solvent by the method described in the specifications of Japanese Patent Publication No. 42-8704, Japanese Patent Publication No. 43-6636, or Japanese Patent Publication No. 46-20814. . In this hydrogenation,
At least 50%, preferably 80% or more of the olefinic double bonds in polymer block B are hydrogenated, and the aromatic unsaturated bonds in polymer block A are hydrogenated.
Less than 25% is hydrogenated. One such hydrogenated block copolymer is Ciel.
There is one commercially available from Chemical Company under the trade name "KRATON-G." Component (b) The rubber softener used as component (b) in the present invention is suitably a non-aromatic mineral oil or a liquid or low molecular weight synthetic softener. Mineral oil-based rubber softeners, commonly called process oils or extender oils, are used to soften, increase volume, and improve processability of rubber, and are a mixture of aromatic rings, naphthenic rings, and paraffin chains. A paraffin chain in which the number of carbon atoms accounts for 50% or more of the total carbon atoms is called a paraffin, a naphthene ring has a carbon number of 30 to 45%, and a naphthenic one has an aromatic carbon number of more than 30%. It is considered to be aromatic. The mineral oil-based rubber softener used as component (b) of the present invention is preferably a naphthenic or paraffinic one in the above category, and has an aromatic carbon number of 30%.
The above aromatic compounds are not preferred in terms of dispersibility in the composition with component (a). The properties of these non-aromatic rubber softeners include a kinematic viscosity of 20 to 500 cst at 37.8°C, a pour point of -10 to -15°C, and a flash point of 170 to 300°C. As the synthetic softener, polybutene, low molecular weight polybutadiene, etc. can be used, but the above-mentioned mineral oil-based softeners for rubber give better results. Component (c) The isotactic propylene homopolymer used as component (c) in the present invention is a polymer that is thermally decomposed by heat treatment in the presence of peroxide to reduce the molecular weight and increase the fluidity of the resin. It is crystalline polypropylene. MFR of this resin (ASTM-
D-1238-L conditions, 230℃) is 0.1 to 50g/10 minutes,
Particularly preferred is a range of 0.5 to 30 g/10 minutes. (d) Component The carbon black used as component (d) in the present invention is a general conductive carbon black such as furnace black, acetylene black, thermal black, channel black, etc. In particular, it is advantageous to use a special furnace black (trade name of AKZO), which has a large specific surface area, in that a high degree of conductivity can be obtained with a small amount of blending. The present invention uses the above-mentioned components (a), (b), (c) and (d), and their blending ratio is: (a) 100 parts by weight of component (b) 180 to 500 parts by weight of component parts, preferably 300 to 500 parts by weight, (c) 30 to 400 parts by weight, preferably 80 to 300 parts by weight, and (d) 50 to 500 parts by weight, preferably 80 to 400 parts by weight. If a carbon black with a large specific surface area is used as component (d), component (b) will be within a preferable range.
This makes it easy to blend 300 to 500 parts by weight. In particular, the use of Ketchen black having a specific surface area of 900 m ² /g or more is advantageous for blending a large amount of component (b). When 300 to 500 parts by weight of component (b) is used, the moldability of the composition becomes good. In the present invention, it is possible to use a surprisingly large amount of component (b), but if it exceeds the above range, it is unfavorable from the viewpoint of bleeding, while if it is less than the above range, it is unfavorable from the viewpoint of moldability and economical efficiency. Furthermore, if the content of component (c) is above the above range, it is unfavorable in terms of flexibility, while if it is below the above range, it is unfavorable in terms of high temperature compression set. Furthermore, if component (d) exceeds the above range, it is unfavorable in terms of mechanical strength, while if it is less than the above range, it is unfavorable in terms of electrical conductivity. The composition of the present invention may further contain inorganic fillers other than carbon black, if necessary. Examples of inorganic fillers include calcium carbonate,
Talc, magnesium hydroxide, mica, clay,
Aluminum hydroxide, barium sulfate, silica, titanium oxide, wollastonite, glass fiber, graphite, etc. can be used. In particular, by incorporating graphite, it is possible to further improve electromagnetic shielding properties in addition to conductivity. Further, an olefin resin other than the above-mentioned component (c) may be further blended within a range that does not significantly impair the effects of the present invention. In particular, a copolymer of propylene and one or more α-olefins other than propylene,
Those having a density of 0.883 to 0.901 g/cm ³ are preferable in terms of the balance of flexibility, processability, heat deformation resistance, and mechanical strength of the composition. Composite The conductive polymer composition of the present invention is obtained by compounding each of the above-mentioned components, and the blending ratio of each component is determined as appropriate within the above-mentioned blending range depending on the use of the resulting composition. selected. As the means for compounding, methods used in the production of ordinary resin compositions or rubber compositions can be adopted, and basically mechanical melt-kneading is used.
Since the composition of the present invention uses a large amount of the softener (component (b)), components (a) and (b), and in some cases, component (c) are also added to prepare a common solvent, e.g. It is more efficient to dissolve it in toluene or the like, then remove the solvent by steam stripping to form a crumb, and then compound the resulting crumb with other components by a mechanical melt-kneading method. As the mechanical melt-kneading method, general melt-kneaders such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, and various kneaders can be used. Applications and Uses The compositions of the invention may optionally contain pigments, heat stabilizers, etc., as is done for conventional resin compositions.
Additives such as antioxidants and ultraviolet absorbers can also be added. Further, the composition of the present invention can be molded with a commonly used thermoplastic resin molding machine, and
Specifically, it is applicable to thermoplastic resin molding methods such as injection molding, extrusion molding, blow molding, and calendar molding. Multilayer injection molding with ordinary polyolefin resin, etc.
By molding by multilayer extrusion molding or the like, it is also possible to obtain a laminate molded product in which one layer on the surface or inner surface is conductive and the other layer on the surface or inner surface is insulating. The conductivity of the composition of the present invention is determined by the amount of the above-mentioned components (a), (b), (c), and (d), the amount of inorganic fillers other than carbon black, and the compounding process. The volume resistivity is controlled in the range of 10 ¹² to ^{10 −1} Ω·cm, which is controlled by the state of dispersion of each component through the process. Volume resistivity is 10 ¹² to ^{10 0} Ω・cm, preferably
Those with a volume resistivity of 10 ⁸ to 10 ⁰ Ω・cm are effective for preventing static electricity damage, and those with a volume resistivity of 10 ^{0 to 10 0}
10 ^-1 Ω・cm is effective not only for preventing static electricity interference but also for electromagnetic shielding materials (prevention of electromagnetic interference). The conductive polymer composition of the present invention can be used in various electronic products, parts, wire-related products, automobile parts, and the like. Specific applications include conductive gaskets,
It can be applied to a wide range of fields such as gaskets, mats, gloves and sacks, hoses, seal parts, and connector parts. In the following Examples and Comparative Examples, the test methods used for various evaluations are as follows. (1) Conductivity - Volume resistivity [Ω・cm] SRIS standard 2301-1969 Wheatstone bridge method. (2) Hardness [-] JIS-K-6301, A type. (3) Tensile strength [Kg/cm ² ] and tensile elongation [%] JIS-K-6301, the sample used was a 2 mm thick in-die extension sheet, and the test piece was No. 3 type. (4) Compression set [%] JIS-K-6301, 100℃, 22 hours, 25% deformation. (5) Injection moldability Injection molding machine: 5 oz in-line screw type. Mold: 100mm x 100mm x 2mm thick sheet Injection pressure: 500Kg/cm ² Injection temperature: 230℃ Mold temperature: 100 x 100 when injection molding is performed under conditions of 40℃ or higher
×2 If it was possible to mold a sheet of each mm thickness, there was no delamination or deformation, and there were no flow marks that significantly deteriorated the appearance, the injection moldability was judged to be good. (6) Stickiness of molded product Two sheets of 100 x 100 x 2 mm thick each obtained by the above injection molding are stacked, a load of 1 kg is applied on top of them, and after being left at room temperature for 24 hours, the two sheets are separated. If no blocking was observed when the two sheets were removed and the two sheets were peeled off, the stickiness was judged to be good. Further, each component used in Examples and Comparative Examples is as follows. (1) Component (a) KRATON-G1651 manufactured by Ciel Chemical Co., Ltd.
(Brookfield viscosity: 20% by weight toluene solution,
2000cps (77〓), n in the above general formula is 1. ) (2) Component (b) Diana Process Oil PW-90 manufactured by Idemitsu Kosan Co., Ltd.
(Paraffin type) (3) Component (c) PP-1: Polypropylene resin manufactured by Mitsubishi Yuka Co., Ltd.
MA-4<MFR (230℃) 5.0g/10 minutes, density 0.905g/ ^cm3 > PP-2: Propylene-ethylene copolymer resin manufactured by Mitsubishi Yuka Co., Ltd. SP-X 9800<MFR (230
°C) 1.5 g/10 minutes, density 0.892 g/cm ³ > (4) Component (d) Ketsuen Black: Manufactured by AKZO, specific surface area
1100m ² /g Acetylene black: manufactured by Denki Kagaku Co., Ltd., specific surface area
70m ² /g Example 1 After mixing the above (a), (b), (c) and (d) components in various proportions using a super mixer, the mixture was mixed using a Banbury mixer at 180°C and 80 rpm for 10 minutes. A composition was obtained by melt-kneading. Various physical properties of these compositions were measured. The results are shown in Table 1. As can be seen from Table 1, the products of the present invention were excellent in electrical conductivity, flexibility, tensile strength and elongation, and compression set, and had good injection moldability.

【table】

[Table] * indicates comparative example Example 2 A conductive packing was molded by injection molding using the No. 1 composition of Example 1, and a packing with excellent electromagnetic shielding properties was obtained.

Claims (1)

[Claims] 1 (a) General formula A(-B-A)n (where A is a monovinyl-substituted aromatic hydrocarbon polymer block, B is a conjugated diene elastomeric polymer block, 100 parts by weight of a hydrogenated derivative of a copolymer represented by (n is an integer from 1 to 5), (b) 180 to 500 parts by weight of a softener for non-aromatic rubber, (c) isotactic propylene monomer. Combined 30~
400 parts by weight and (d) 50 to 500 parts by weight of conductive carbon black.