JP2005325261A - Crosslinkable rubber composition for surface conductive rubber material, surface conductive rubber material formed by crosslinking the composition, and its application - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crosslinkable rubber composition capable of giving, by the same method as that of molding a conventional rubber material and easily from the specific crosslinkable rubber composition, a monolayer-structure, surface conductive rubber material which has a small surface resistivity and has (semi)conductivity only on the surface, which has a high volume resistivity, or insulating property in the direction of the front and rear surfaces and which has as a rubber material sufficient physical properties (hardness, modulus, compression set, etc.), and capable of unnecessitating, as to the obtained rubber material, further processes corresponding to the conventional surface treatment and the like; and to provide a surface conductive rubber material having the above characteristics. <P>SOLUTION: The surface conductive rubber material is formed by crosslinking the crosslinkable rubber composition containing a crosslinkable rubber, an organized layered compound and a conductive filler, and has a surface resistivity of ≤10<SP>6</SP>Ω and a volume resistivity of ≥10<SP>10</SP>Ωcm. The crosslinkable rubber composition for the surface conductive rubber material is provided which comprises (i) the crosslinkable rubber, 2.0-15.0 pts.wt. of the organized layered compound, 3.0-10.0 pts.wt. of the conductive filler, each based on 100 pts.wt. of the rubber, and a crosslinking agent. The surface conductive rubber material obtained by crosslinking the composition is also provided. The above layered compound is preferably the one wherein a layered inorganic compound is subjected to organization treatment with an ammonium salt. The above crosslinking treatment is preferably the one wherein the crosslinkable rubber composition is subjected to a primary heating/vulcanization/molding followed by a secondary vulcanization. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a crosslinkable rubber composition for a surface conductive rubber material, a surface conductive rubber material obtained by crosslinking the composition, and use thereof, and more particularly, a rubber material having a single-layer structure, A crosslinkable rubber composition for a surface conductive rubber material having a low resistance, a surface of the rubber material having (semi) conductivity, a large volume resistance, and an insulating property in a direction perpendicular to the surface. The present invention relates to a cross-linked surface conductive rubber material, a production method thereof, and a use thereof.

  In recent years, in semiconductor industries such as LSI, artificial satellite industry such as rockets and their control devices, factories that produce and use electronic devices such as computers, electronic cameras, mobile phones, and precision machinery such as robots, nuclear power plants, etc. Production equipment, control rooms, workers' clothes, shoes, etc. are also required to have high anti-electricity performance.

  In such production facilities and control rooms, for example, floor materials, wall materials, work tables, clothes, shoes, etc., can suppress the generation of static electricity, and can quickly reduce without static electricity generation even if static electricity occurs. -Insulation from the floor (substrate) etc. is also required so that workers wearing the clothing etc. that are in contact with the floor or walls due to electric leakage etc. are not damaged.

  As flooring materials and wall materials used for such applications, for example, they are flat and the surface is electrically conductive, and the direction perpendicular to the surface (the direction through the front and back surfaces) is insulative. In general, a material (molded body) in which two types of materials, a conductive metal foil and an insulating polymer material, are joined to form a two-layer structure is used.

  However, in order to manufacture such a sheet having a layer structure of two or more layers, it is necessary to laminate the melt-extruded insulating polymer material with the metal foil, which complicates the manufacturing process and peels off at the joint surface. There is a problem.

  Further, in order to obtain a molded body having conductivity only on the surface and insulating in the thickness direction of the layer, there is a method of surface-treating the surface of the insulating polymer material with a conductive polymer or the like, There is concern over the complexity of the manufacturing process.

  It is also possible to make the insulating polymer conductive by blending a conductive filler, but the insulating polymer and the conductive filler were melt-kneaded and extruded into a desired shape. In this case, the component composition becomes uniform regardless of the part, and conductivity is developed on the surface and inside of the obtained molded body. Therefore, in order to provide insulation only in the thickness direction of the molded body, it is necessary to separately provide an insulating layer on the surface thereof to have a two-layer structure or the like, and the manufacturing process becomes two or more steps, which is complicated.

  If there is no special surface treatment etc., it is possible to develop a rubber material having a single layer structure in a single step, insulating in the thickness direction, and having a conductive surface, and a method for manufacturing the same. If possible, there is a possibility that the manufacturing cost of the rubber material used for the above-described applications can be significantly reduced.

Therefore, as a result of intensive studies to solve the above problems, the present inventors have included a crosslinkable rubber, a layered compound subjected to a specific treatment, a conductive filler, and a crosslinker if necessary. When the crosslinkable rubber composition is used, it is composed of a rubber material having a single-layer structure in a single step and by the same vulcanization (crosslinking) molding method as in the prior art. A rubber material having conductivity and sufficient physical properties (hardness, modulus, compression set, etc.) as a rubber material is obtained, and a new process such as surface treatment is not required. The present inventors have found that the manufacturing cost can be significantly reduced and have completed the present invention.

Examples of the resin composition or rubber composition containing the organic layered inorganic layered compound include the following.
For example, (a) JP 2000-178422 A (Patent Document 1) discloses an inorganic layered compound and polybutylene terephthalate (PBT), polycarbonate, polyethylene terephthalate, phenol resin, phenoxy resin, fibrous reinforcing material, fluorine-based resin. In addition, a flame-retardant polybutylene terephthalate resin composition for electrical product terminal members containing carbon black and the like is disclosed, and is described as being excellent in flame retardancy, low warpage, heat resistance, self-tapping properties, and the like.

  In addition, examples of the inorganic layered compound include kaolinite, talc, smectite, mica, and the like, and an organic treatment for exchanging inorganic ions between layers with organic ions may be performed, and 0 to 30 weights with respect to 100 parts by weight of PBT. It is also described that it is added in parts.

  (B) Japanese Unexamined Patent Publication No. 2000-226585 (Patent Document 2) discloses a flame retardant containing an inorganic layered compound and a flame retardant molded article containing the same. From the viewpoint of flame retardancy, an inorganic layered compound is disclosed. It is also described that it is contained in an amount of 1% by weight or more.

Further, it is described that the flame retardant may contain a resin having a relatively slow combustion rate such as a polyolefin resin.
(C) Japanese Patent Application Laid-Open No. 7-82398 (Patent Document 3) discloses an antifogging agent composition containing a mixed colloid solution, an anionic surfactant, an organic electrolyte, an inorganic layered compound, and the like, and dispersing it in a dispersant. An anti-fogging agent that has been applied to the surface of a thermoplastic resin film and then dried is disclosed.

(D) Japanese Patent Application Laid-Open No. 7-205376 (Patent Document 4) includes a layer composed of a resin composition containing an inorganic layered compound having a particle size of 5 μm or less and an aspect ratio of 50 to 5000, and a resin , a heat seal layer, A gas barrier packaging bag having the following is disclosed.

  (E) In JP-A-8-302025 (Patent Document 5), a layered compound is brought into contact with an organic cation, then swelled with an organic solvent, and then the obtained product is kneaded with an elastomer to obtain high rigidity. A manufacturing method of an inorganic filler-containing elastomer having heat resistance and impact resistance and a composite resin material excellent in impact resistance are disclosed, and it is described that a fine inorganic filler can be contained in the elastomer at a high concentration. Examples of the elastomer include ethylene propylene copolymer (EPR), EBR, EPDM, SBR, BR, POR, SEBS and the like.

  However, Patent Document 5 does not relate to a conductive rubber material that can be suitably used as an anti-static molded body. In Patent Document 5, a crosslinkable fluororubber composition in which an unvulcanized fluororubber and a crosslinking agent, a co-crosslinking agent, and the like are blended is prepared by kneading blended components, and the like. There is no description or suggestion about the technical idea of vulcanizing (crosslinking) the composition into a desired shape within the mold.

(F) Japanese Patent Application Laid-Open No. 11-263876 (Patent Document 6) discloses an organic-inorganic composite (filler) in which an organic compound or a polymer thereof is intercalated between layers of a layered compound, and the composite A hybrid material in which (filler) is finely dispersed in a polymer matrix is disclosed, the mutual force between the polymer matrix and the composite is strong, has sufficient mechanical properties, and is useful for molding materials, films, etc. It is described.

  (G) JP-A-11-293033 (Patent Document 7) describes an organic-inorganic composite obtained by adding a solvent to the organic-inorganic composite (filler) described in JP-A-11-263876 (Patent Document 6). A body composition and a hybrid material in which the composition is finely dispersed in a polymer matrix are disclosed, and are described as having the same effect as Patent Document 6 above.

  However, among these Patent Documents 1-7, except for Patent Document 5, all attempts are made to improve various physical properties of the resin compound by blending the layered compound into the resin. It is not intended to obtain a conductive rubber material that can be suitably used.

Further, Patent Document 5 does not relate to a conductive rubber material that can be suitably used as an anti-static molded body. Moreover, in Patent Document 5, an organic / inorganic composite is blended and used together with an unvulcanized elastomer (uncrosslinked product), a crosslinking agent, a co-crosslinking agent and the like, and this compound is crosslinked (vulcanized) into a desired shape. ) There is no technical idea of molding.
JP 2000-178422 A JP 2000-226585 A JP-A-7-82398 JP-A-7-205376 JP-A-8-302025 JP-A-11-263876 Japanese Patent Laid-Open No. 11-293033

The present invention is intended to solve the problems associated with the prior art as described above, and can be easily obtained from a specific crosslinkable rubber composition in the same manner as the conventional method of molding a rubber material. Low surface resistivity, only surface (semi) conductivity, high volume resistivity in the front and back direction, insulation, and sufficient physical properties (hardness, modulus, compression set, etc.) as a rubber material1 A surface-conductive rubber material having a layer structure is obtained, and the obtained rubber material does not require a further step corresponding to a conventional surface treatment, etc., and a surface-conductive rubber having the above characteristics The purpose is to provide materials.

Another object of the present invention is to provide a low-cost anti-static molded body comprising the conductive rubber material and having the above properties in a well-balanced manner.
Another object of the present invention is to provide a simple (efficient) and safe manufacturing method of the conductive rubber material having the above-described characteristics.

The surface conductive rubber material according to the present invention comprises a crosslinkable rubber composition containing a crosslinkable rubber, an organically treated layered compound, and a conductive filler, and has a surface resistivity of 10 ⁶ Ω.
The volume resistivity is 10 ¹⁰ Ω · cm or more.

The crosslinkable rubber composition for the surface conductive rubber material according to the present invention is:
(i) a crosslinkable rubber;
For 100 parts by weight of the rubber,
(ii) 2.0 to 15.0 parts by weight of an organically treated layered compound;
(iii) 3.0 to 10.0 parts by weight of conductive filler;
(iv) It is characterized by comprising a crosslinking agent.

The surface conductive rubber material according to the present invention is characterized in that the crosslinkable rubber composition is subjected to a crosslinking treatment.
In the present invention, the cross-linking treatment is preferably performed by secondary vulcanization after the cross-linkable rubber composition is subjected to primary heat vulcanization molding.

The surface conductive rubber material according to the present invention is:
(ia) a crosslinked rubber;
For 100 parts by weight of the rubber,
(ii) 2.0 to 15.0 parts by weight of an organically treated layered compound;
(iii) 3.0 to 10.0 parts by weight of conductive filler;
It is characterized by comprising.

Any of the above surface conductive rubber materials according to the present invention preferably has a surface resistivity of 10 ⁶ Ω or less and a volume resistivity of 10 ¹⁰ Ω · cm or more.
The antistatic molded article according to the present invention is characterized by comprising only the surface conductive rubber material described in any of the above or using at least a part of the surface conductive rubber material.

The method for producing a surface conductive rubber material according to the present invention includes:
(i) a crosslinkable rubber;
(ii) an organically treated layered compound;
(iii) a conductive filler;
(iv) A crosslinkable rubber composition containing a crosslinking agent is subjected to a crosslinking treatment.

  According to the present invention, it has a single-layer structure, has no delamination, has conductivity only on the surface, has insulation in the front and back directions, and has sufficient physical properties (hardness, modulus, compression set) as a rubber material. And the like, and more preferably, a surface conductive rubber material having a good balance of properties and an antistatic molded article having excellent properties using the same are provided at low cost.

  Further, according to the above production method of the present invention, the surface conductive rubber material having the above characteristics from the crosslinkable rubber composition is subjected only to vulcanization molding (and further, by performing pressure, stretching, etc. if necessary). )) The surface conductive rubber material obtained efficiently and easily does not require a new step such as further surface treatment, and the manufacturing cost of the surface conductive rubber material can be significantly reduced.

  Further, according to the present invention, there is provided a crosslinkable rubber composition from which a surface conductive rubber material having the above characteristics can be obtained only by performing ordinary vulcanization molding.

Hereinafter, the crosslinkable rubber composition for the surface conductive rubber material according to the present invention, the surface conductive rubber material obtained by crosslinking the composition, and the production method thereof will be specifically described.
The surface conductive rubber material according to the present invention includes (i) a crosslinkable rubber, (ii) an organically treated layered compound, (iii) a conductive filler, and (iv) a crosslinker, if necessary. The resulting crosslinkable rubber composition is crosslinked (vulcanized). In a preferred embodiment of the surface conductive rubber material, the surface specific resistance is 10 ⁶ Ω or less and the volume specific resistance is 10 ¹⁰ Ω · cm or more.

[Crosslinkable rubber composition]
First, the crosslinkable rubber composition will be described.
<Crosslinkable rubber (i)>
The crosslinkable rubber (unvulcanized rubber) (I) contained in the crosslinkable rubber composition may be any of natural rubber and synthetic rubber, and may be either binary or ternary. There are no particular restrictions on the type of vulcanization (crosslinking) such as vulcanization, sulfur-containing vulcanization, and crosslinking with energy rays (eg, electron beam), and conventionally known ones can be appropriately selected and used.

  Examples of the crosslinkable rubber (i) include ethylene-propylene-diene rubber (EPDM), ethylene-propylene rubber (EPR), natural rubber, butyl rubber, nitrile rubber, polyisoprene rubber, polybutadiene rubber, silicone rubber, styrene-butadiene rubber, Non-vulcanized materials such as chloroprene rubber, acrylic rubber, fluoro rubber (eg vinylidene fluoride / hexafluoropropylene / tetrafluoroethylene ternary fluoro rubber) can be mentioned. It is preferable because it is excellent and can be used for a wide range of applications.

These crosslinkable rubbers may be used alone or in combination.
<Organized layered compound (ii)>
The layered compound (host, untreated) or swellable clay mineral to be subjected to the organic treatment is not limited in kind such as natural products and synthetic minerals. For example, [0014] of JP-A-8-302025 Swellable clay minerals as described in the column, specifically, natural or synthetic mica (mica), natural or synthetic smectite, vermiculite, chlorite, etc., among which synthetic mica (mica), synthetic smectite This is preferable in that there are few impurities. The average particle diameter (D50) of these layered compounds is usually about 0.1 to 100 μm, preferably about 0.1 to 2 μm. These untreated layered compounds may be used alone or in combination.

  As the organic treatment agent, that is, the compound (guest) that organicizes the layered compound, an alkylamine salt (also referred to as an ammonium salt or an amine salt) represented by the formula (a) as described later is preferable. These alkylamine salts that are guests may be commercially available as described later, and the higher the purity, the better.

  For example, in the alkylamine salt (a), the compounding ratio [layered compound to be subjected to organic treatment (host) / compound to make the layered compound organic (guest)] is [0016] of JP-A-8-302025. The “cation exchange capacity (CEC) for the layered compound” described in the column is determined, and the amount is desirably 1 to 10 equivalents relative to CEC.

  In detail, as the organically treated layered compound (ii) or a preparation method thereof, a conventionally known one or a preparation method can be appropriately employed. For example, JP-A-8-302025 (Patent Document 9) Items and methods described in columns [0014] to [0021], items and methods described in column [0036] of JP-A-2000-178422 (Patent Document 5), JP-A-2000-226585 (Patents) The method and method described in columns [0005] to [0013] of Document 6) and those described in columns [0016] to [0019] of JP-A-7-82398 (Patent Document 7) may be used.

  As a method for preparing the organically treated layered compound (ii), for example, first, water and a hydrophilic layered compound (example: hydrophilic) which is a layered compound (host) excellent in swelling property or cleavage property in water. Mica etc.).

Next, an amine derivative such as an ammonium salt (eg, quaternary ammonium salt) as an organic treatment agent (guest) for the layered compound is added to the mixed solution, and the mixture is stirred and mixed.
Thus, when a layered compound and an ammonium salt are brought into contact and reacted by adding and mixing, for example, an ammonium salt to the mixed solution of the layered compound, for example, in hydrophilic mica, sodium ions (Na ⁺ ) Is an organic molecule, for example, a cation of a quaternary ammonium salt (quaternary ammonium ion), for example, [N (R ¹ ) (R ² ) (R ³ ) ( R ⁴ )] ⁺¹ (wherein R ^{1 to} R ⁴ are all alkyl groups, etc.), and exchange of ions is performed, or the inclusion and coordination of the quaternary ammonium salt molecule It is considered that organic cations and organic molecules are intercalated (inclusion) between the layers.

  Treatment with an ammonium salt, which is a product of such a reaction [for example, ion exchange treatment or treatment such as coordination bonding or inclusion of a quaternary ammonium salt (molecule). The layered compound (ii) thus formed is not cleaved or dispersed in the presence of water, and becomes a precipitate. This layered compound (ii) is also referred to as an interlayer compound.

The reaction mixture is then filtered and the resulting filtrate is washed, for example, with water,
After removal of the unreacted product, the layered compound (ii) treated with an ammonium salt (amine salt)
) Is obtained. In such a treatment, it is considered that a layered compound (ii) in which ammonium ions are intercalated in the host is obtained in many cases.

The obtained filtrate is dried and then pulverized using a ball mill or the like, if necessary, to obtain a layered compound (ii) having a desired particle size treated with an ammonium salt.
Examples of amine derivatives such as the ammonium salt (amine salt) include ammonium salts (amine salts) described in, for example, columns [0015] to [0018] of JP-A-8-302020. The following alkylammonium salts (a-1) described in the publication;
Hydrochlorides, odorates and the like of amines (for example, aliphatic and aromatic primary to tertiary amines) as described in [0006] column of JP-A-9-194822; and amines An aqueous solution of

  That is, as an amine derivative represented by an ammonium salt (amine salt) that can be used in the present invention, a general formula (a):

[In the formula (a), R ¹ , R ² , R ³ and R ⁴ are each independently a hydrogen atom (H) or an alkyl group having about 1 to 30 carbon atoms which may have a branch, a substituent ( An aromatic hydrocarbon group having a total carbon number of about 6 to 25 which may have a C1-5 alkyl group, etc., and at least one of these R ¹ , R ² , R ³ , R ⁴ is hydrogen A group other than an atom. (In a preferred embodiment, the carbon number of the main chain of R ⁴ is the same as or larger than the carbon number of the main chain of R ¹ , R ² , R ³ ,
It is preferably about 30. ) X represents an anion of an acid constituting the salt (for example, a halogen ion such as Cl ⁻ , NO ₃ ⁻ , SO ₄ ²⁻ ) or the like. m represents the valence of the anion, and preferably 1, 2, and especially 1. ]
The thing represented by is mentioned.

  As amine derivatives such as ammonium salts (amine salts), more specifically, for example,

[In Formula (a-1), n is an integer of about 1 to 20. X represents, for example, Cl ⁻ , NO ₃ ⁻ , SO ₄ ²⁻ or the like. m represents the valence of the anion X, preferably 1. ] Is preferable.
Examples of such an organic ammonium salt include organic ammonium salts having a total carbon number of 4 to 23 described in [0015] column of JP-A-8-290907. As belonging to a) and not belonging to (a-1), alkyl or aryltrimethylammonium salts such as tetramethylammonium salt, tetraethylammonium salt, phenyltrimethylammonium salt, dioctyldimethylammonium salt, didecyldimethylammonium salt, etc. Or diaryldimethylammonium salt.

Examples of those belonging to the formula (a-1) include ethyl trimethylammonium salt, propyltrimethylammonium salt, butyltrimethylammonium salt, pentyltrimethylammonium salt, hexyltrimethylammonium salt, heptyltrimethylammonium salt, octyltrimethylammonium salt. Salt, nonyltrimethylammonium salt, decyltrimethylammonium salt, dodecyltrimethylammonium salt, tetradecyltrimethylammonium salt and the like.

These organic ammonium salts may be used alone or in combination of two or more.
Such amine derivatives such as alkylamine salts are conventionally known, for example, (
It can be obtained by reacting a primary to tertiary alkylamine and the like with an acid (eg, hydrochloric acid, nitric acid, sulfuric acid, etc.), water, an alkyl halide, an aryl halide and the like.

Further, specific examples of (first to third) alkylamines used in forming such alkylamine salts (alkylammonium salts) and the like include, for example, ammonia (NH ₃ ).
₁ to 3 n-hexylamine, n-dodecylamine, n-octadecylamine having a structure in which 1 to 3 of H is substituted with an alkyl group (C _n H _{2n + 1} , n = 1 to 20) And the like. Among them, primary to tertiary n-dodecylamine is preferable.

The ammonium salts as described above may be used alone or in combination of two or more.
Among the organically-treated layered compounds (ii), “Somasif MEE” {manufactured by Coop Chemical Co.}, “Smectite SAN” {manufactured by Coop Chemical Co.}, “Smectite STN” {manufactured by Coop Chemical Co., Ltd. } Etc. are mentioned.
<Conductive filler (iii)>
Examples of the conductive filler (iii) include particles, fibers, and scales.

  Examples of the particulate filler include metals such as conductive carbon black (eg, ketjen black), nickel, copper, iron, silver, and metal oxides such as tin oxide and zinc oxide.

  Examples of the fibrous filler include PAN- and pitch-based carbon fibers, metal fibers such as brass, stainless steel, and aluminum, and carbon-coated fibers such as carbon fibers and glass fibers that are surface-coated with nickel and aluminum. .

Examples of the flaky filler include metal flakes such as graphite, aluminum, copper, and nickel.
In the present invention, these conductive fillers may be used alone or in combination of two or more. <Crosslinking agent (iv)>
The crosslinking agent (vulcanizing agent) (iv) is appropriately selected from conventionally known ones according to the type of the crosslinkable rubber (i) as necessary.

  In the present invention, as the cross-linking agent, a peroxide-based cross-linking agent (peroxide-based cross-linking agent) is excellent in balance in terms of chemical resistance, mechanical properties, etc., and a cross-linked fluororubber molded article can be obtained. From the point of view, it is preferable.

As such a peroxide-based crosslinking agent, conventionally known ones can be widely used. Specifically, for example,
2,5-dimethyl-2,5-di (t-butylperoxy) hexane (“Perhexa 25B” manufactured by NOF Corporation), dicumyl peroxide (“PARK Mill D” manufactured by NOF Corporation), 2,4-dichlorobenzoyl Peroxide, di-t-butyl peroxide, t-butyl dicumyl peroxide, benzoyl peroxide (manufactured by NOF Corporation, “Nyper B”), 2,5-dimethyl-2,5- (t-butylperoxy) hexyne -3 (Nippon Yushi Co., Ltd., “Perhexine 25B”), 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, α, α′-bis (t-butylperoxy-m-isopropyl) benzene ( “Nippon Yushi Co., Ltd.
Perbutyl P "), t-butyl peroxyisopropyl carbonate, parachlorobenzoyl peroxide, t-butyl perbenzoate, and the like.

Of these, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, benzoyl peroxide, and α, α′-bis (t-butylperoxy-m-isopropyl) benzene are preferred.

These crosslinking agents may be used alone or in combination of two or more.
<Co-crosslinking agent (v)>
Specific examples of the co-crosslinking agent (vulcanization aid) (v) blended as necessary include triallyl isocyanurate (manufactured by Nippon Kasei Co., Ltd., “TAIC”), triallyl cyanurate, trially formal. , Triallyl trimellitate, N, N′-m-phenylenebismaleimide, dipropargyl terephthalate, diallyl phthalate, tetraallyl terephthalamide, and the like.
Of these, triallyl isocyanurate is preferable in terms of heat resistance and the like.

In this crosslinkable rubber composition, (i) with respect to 100 parts by weight of the crosslinkable rubber,
(ii) The organically treated layered compound (interlayer compound) is usually in an amount of 2.0 to 15.0 parts by weight,
(iii) The conductive filler is usually in an amount of 3.0 to 10.0 parts by weight,
(iv) The amount of the crosslinking agent is not particularly limited, but it is preferably contained in an amount of 0.5 to 2.0 parts by weight.

  Moreover, when a co-crosslinking agent (v) is blended if necessary, this co-crosslinking agent (v) is usually in an amount of 2.0 to 8.0 parts by weight, preferably 4.0 to 6.0 parts by weight. It is desirable to be included.

Further, if the content of the layered compound (ii) is less than the above range, the volume resistivity tends to decrease, and if it is more than the above range, molding failure tends to occur.
Further, the surface conductive rubber material obtained when the content of the conductive filler (iii) is less than the above range is insulative, and when the content is more than the above range, the conductivity is high but the surface of the molded material is bad. There is a tendency to develop tackiness.

Further, when the content of the crosslinking agent (iv) is less than the above range, the surface conductive rubber material obtained tends to be insufficiently crosslinked, and when it exceeds the above range, molding tends to be poor.
Further, when the content of the co-crosslinking agent (v) is less than the above range, the surface conductive rubber material obtained tends to have a decrease in tensile strength and a deterioration in compression set rate. The kneading workability at the time tends to deteriorate.
<Other ingredients>
The crosslinkable rubber composition according to the present invention contains the above components (i), (ii), (iii) and, if necessary, the component (iv), the component (v) and the like. Agents, organic / inorganic fillers, organic / inorganic pigments and the like may be contained in appropriate amounts.

[Method for producing crosslinkable rubber composition]
The method for producing the crosslinkable rubber composition according to the present invention comprises the above-mentioned amount of the crosslinkable rubber (i), the organically treated layered compound (ii), the conductive filler (iii), and, if necessary, a crosslinking agent (
iv) and, if necessary, the co-crosslinking agent (v) and the like may be added at once or in any order and mixed, that is, stirred, kneaded, or the like.

  In this mixing, if necessary, kneading may be performed using a commercially available Banbury, open roll, kneader, biaxial kneader or the like. Moreover, you may perform heating (example: 50-100 degreeC) etc. at the temperature which the vulcanization (crosslinking) of the said crosslinkable rubber (i) does not advance substantially if necessary.

  In the present invention, as the layered compound to be added in the production of the crosslinkable rubber composition, it is a production process that a compound previously treated with an amine derivative such as a quaternary ammonium salt is blended. Needed for simplicity.

  Here, instead of the above (ii) “Organized layered compound”, “Unorganized layered compound and organic agent (eg, quaternary ammonium salt, alkylamine salt, etc.) (I) a crosslinkable rubber, (iii) a conductive filler, if necessary (iv) a crosslinker, and optionally (v) ) Even when mixed with a co-crosslinking agent, etc., a vulcanized product cannot obtain a crosslinked rubber molded product having the desired physical properties, ie, (conductive only on the surface), probably because of the following reasons. That is, the organic treatment reaction (intercalation) proceeds only when the layered compound is cleaved, and the layered compound that has not been organically treated is cleaved and dispersible. Bad Therefore, seems to be unable to maximize the insulating effect not spread uniformly organic treatment agent layer compound material, it may be due.

[Surface conductive rubber material]
The conductive rubber material according to the present invention is obtained by subjecting a crosslinkable rubber composition to the above-mentioned crosslinking treatment by a conventionally known method. Such a crosslinking treatment is performed by first heating the crosslinkable rubber composition. From the viewpoint of improving tensile strength and compression set, it is desirable to perform secondary vulcanization after vulcanization molding.

The surface conductive rubber material according to the present invention is characterized by comprising (ia) a crosslinked rubber, (ii) an organically treated layered compound, and (iii) a conductive filler.
In this conductive rubber material, it is presumed that the layered compound (ii) contained is oriented in the plane direction, as will be described later. Therefore, in this conductive rubber material, in particular, the low surface specific resistance as described later is low. It is considered that high volume resistivity is expressed.

In the surface conductive rubber material of the present invention, (ii) the organically treated layered compound is usually in an amount of 2.0 to 15.0 parts by weight relative to 100 parts by weight of (ia) the crosslinked rubber.
(iii) It is desirable that the conductive filler is contained in an amount of 3.0 to 10.0 parts by weight.

  If the content of the layered compound (ii) with respect to the crosslinked rubber (ia) in the surface conductive rubber material of the present invention is less than the above range, the volume resistivity tends to decrease, and more than the above range. Tends to be defective.

  Further, if the content of the conductive filler (iii) relative to the crosslinked rubber (ia) is less than the above range, it tends to be insulative, and if it is more than the above range, the conductivity becomes high, but after molding, There is a tendency for the material surface to develop a terrible tackiness.

The surface conductive rubber material according to the present invention has a surface specific resistance (conforming to JIS K6911) of 10 ⁶ Ω or less, particularly 10 ³ to 10 ⁶ Ω, and a volume specific resistance (conforming to JIS K6911) of 10 ¹⁰ Ω · cm. As described above, in particular, 10 ¹⁰ to 10 ¹⁵ Ω · cm is desirable for preferable use in various applications as described in the “Background Art” column.

The surface conductive rubber material according to the present invention exhibits the above surface specific resistance and volume specific resistance only by performing the normal vulcanization operation as described above, and is also suitable as a vulcanized rubber as described below. As shown in FIG. 1, the physical properties are considered to be due to the following reasons.
<Figure 1>
FIG. 1 schematically shows a sheet-like surface conductive rubber material (rubber sheet) of the present invention. In FIG. 1, the layered compound (ii) that functions as an insulating filler is indicated by “−”, and the conductive filler (iii) is indicated by “•”.

  As shown in FIG. 1, in the surface conductive rubber material of the present invention, the layered compound (ii) which is an insulating compound contained is oriented in the plane direction of the sheet, and accordingly, on the layered compound (ii) Or the conductive filler existing between the layered compound (ii) and the layered compound (ii) is also preferably arranged with high density (continuously or discontinuously) in the surface direction of the sheet. It is thought that there is.

  As a result, in the surface direction of the obtained conductive rubber material such as a sheet, the conductive fillers are arranged more densely (and preferably continuously) than in the thickness direction of the layer. It is considered that the “specific resistance” has decreased.

Moreover, in the front and back direction of the conductive rubber material (sheet), the layered compound (ii) of the insulating compound forms a layer and exists in multiple layers so as to inhibit energization, and between the layered compounds (ii). The intervening conductive filler is also layered thereby and exists more discontinuously in the front and back direction of the sheet). For example, the “volume” is the resistance value in the front and back direction of the sheet-like conductive rubber material. The “specific resistance” is increased in the conductive rubber material of the present invention (see “Example 1”) as compared with the rubber material containing no layered compound (ii) (see “Comparative Example 1”). Conceivable.

In general, the surface resistivity (according to JIS K6911) is in the range of 10 ⁹ Ω to 10 ⁵ Ω in the “semiconductive material” and in the range of 10 ⁴ Ω or less in the “conductive material”. Also,
The volume resistivity (conforming to JIS K6911) is in the range of 10 ¹⁰ Ω · cm or more for the “insulating material” and in the range of 10 ⁹ Ω to 10 ⁵ Ω · cm for the “semiconductive material”. In the case of “material”, it is in the range of 10 ⁴ Ω · cm or less.

[Manufacture of surface conductive rubber material]
The method for producing a surface conductive rubber material according to the present invention comprises the above (i) crosslinkable rubber,
The crosslinkable rubber composition comprising (ii) an organically treated layered compound, (iii) a conductive filler, and (iv) a crosslinker, if necessary, is subjected to a crosslinking treatment.

  As described above, according to the present invention, the structure is a single layer, there is no delamination, only the surface is conductive, that is, the surface specific resistance is small, the surface is conductive, and the insulation between the front and back surfaces, ie, the volume specific resistance is large. An insulating surface conductive rubber material is provided at low cost.

  Crosslinking (vulcanization) may be performed by a conventional method. For example, the crosslinkable rubber composition (compound) may be formed into a desired shape (primary vulcanization) and then secondary vulcanized. it can.

  During primary vulcanization, that is, during molding into a desired shape (also referred to as pre-molding or primary molding), usually maintained at a heating temperature of 140 to 180 ° C. for 5 to 30 minutes under a pressure of 3 to 10 MPa. May be. The above conditions (temperature, pressure, etc.) may be raised or raised continuously or stepwise, then held at a constant temperature, pressure, etc. for a predetermined time, and then lowered or lowered.

  In the present invention, in the primary vulcanization, the kneaded crosslinkable rubber composition may be subjected only to a normal heat and pressure press, but it is desirable to perform a treatment such as stretching. For example, when a raw material rolled by a pressure roller is used as a preform or when molding is performed by an extrusion molding method, shearing acts on the material, and a stretching effect is obtained.

  As a result of the treatment such as pressurization and stretching, the layered compound (ii) which is an insulating compound contained in the crosslinkable rubber composition is oriented in the plane direction of the sheet, and accordingly, on the layered compound (ii) Or the conductive filler existing between the layered compound (ii) and the layered compound (ii) is also considered to be preferably arranged with high density (continuously or discontinuously) in the sheet surface direction. It is done.

In the present invention, a mold or the like can be used for the pressurization and molding, and a stretching roll or the like can be used for the stretching.
“Secondary vulcanization” is, for example, a temperature lower than the decomposition temperature of a compounded component, particularly an organic vulcanized rubber, an organically treated layered compound, etc. at a temperature about 10 to 50 ° C. higher than the primary vulcanization temperature. The heating is performed at 160 to 200 ° C. for 1 to 24 hours.

  As described above, according to the present invention, the surface conductive rubber material having the above characteristics can be obtained only by performing normal vulcanization molding under the above-mentioned pressure, and further, vulcanization molding under such pressure. In addition to the above, if necessary, the film can be efficiently and easily obtained by stretching.

In particular, when the amount of the layered compound (ii) used in the present invention is small, it is more effective to lower the surface conductivity and increase the volume resistance by adding positive stretching to the material. is there. It is presumed that the dispersibility and orientation of the layered compound (ii) are promoted.

Specifically, after roll-rolling as a pretreatment, the material is pre-formed, vulcanized with a mold, or formed by extrusion with a stretching effect, thereby obtaining a stretching effect.
[Anti-static product]
The molded body for anti-electrical resistance according to the present invention is made of only the surface conductive rubber material as described above, or at least partly using this surface conductive rubber material.

Examples of the antistatic molded body made of only the surface conductive rubber material include antistatic films, sheets, mats, wallpaper, printing paper, shoes, and shoe soles.
In addition, as an anti-static molded body using at least a part of this surface conductive rubber material, known methods such as appropriately laminating, pasting and stitching the surface conductive rubber material and other resins, rubber, metals, etc. As described above, the control room wall material, floor material, work table, worker clothes, shoes, gloves, protective glasses, masks, and the like, which are obtained by processing by the above method, can be mentioned.

  These antistatic moldings can suppress the generation of static electricity, and can be quickly reduced or removed without causing electric resistance even if static electricity occurs. In addition, when this antistatic molded body is work clothes, even if the clothes come into contact with the floor, walls, etc. due to electric leakage or the like, the worker wearing the clothes may be obstructed. Absent.

Further, for example, when this anti-static molded body is used as a floor material, insulation from the floor surface (substrate) or the like is also exhibited.
[Example]
Hereinafter, the cross-linkable rubber composition according to the present invention and the surface conductive rubber material (molded body) obtained by vulcanizing (cross-linking) the same will be described more specifically with reference to examples. It is not limited at all by an example.

The conditions for measuring normal physical properties used in the following examples and comparative examples are as follows.
(Hardness)
Based on JIS-K6253, it measured by the durometer type A hardness test at 25 degreeC.
(Tensile strength)
It measured at 25 degreeC based on JIS-K6251.
(Elongation)
It measured at 25 degreeC based on JIS-K6251.
(Compression set)
Based on JIS-K6262, the compression set was measured using a φ29 × 12.5 disk under the conditions of 120 ° C. × 70 hours and a compression rate of 25%.
(100% tensile stress (modulus))
Based on JIS K-6256, the stress when the marked line became 40 mm in width was measured.
(Surface resistivity)
(A) In accordance with JIS K6911, the surface resistivity was measured using a superinsulator (TOA Co., Ltd., model number “DSM8103”).

In general, the surface resistivity (according to JIS K6911) is in the range of 10 ⁹ Ω to 10 ⁵ Ω in the “semiconductive material” and in the range of 10 ⁴ Ω or less in the “conductive material”.
(B) Surface resistivity was measured using a measurement automatic insulation resistance meter (model number “DN-500UB” manufactured by NATIONAL) when the surface resistivity is 10 ⁻⁶ Ω or less.
(Volume resistivity)
In accordance with JIS K6911, the volume resistivity was measured using a superinsulator (TOA Co., Ltd., model number “DSM8103”).

In general, the volume resistivity (according to JIS K6911) is in the range of 10 ¹⁰ Ω · cm or more for the “insulating material” and in the range of 10 ⁹ Ω to 10 ⁵ Ω · cm for the “semiconductive material”. Yes, in the “conductive material”, it is in the range of 10 ⁴ Ω · cm or less.

(1) Production of sample A crosslinkable rubber composition having the composition shown in Table 1 was prepared.
That is, as a crosslinkable fluororubber, a ternary fluororubber [trade name “G9002”, vinylidene fluoride (i) / hexafluoropropylene (b) / tetrafluoroethylene (c) ternary fluororubber], Daikin Industries, Ltd. 100 parts by weight
2.0 parts by weight of an organically treated layered compound (trade name “Somasif MEE”, manufactured by Co-op Chemical)
3.0 parts by weight of conductive filler (trade name “Ketjen Black”, (LION) manufactured by)
1.5 parts by weight of a crosslinking agent (“Perhexa 25B”, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, manufactured by NOF Corporation)
4.0 parts by weight of a co-crosslinking agent (“TAIC”, triallyl isocyanurate, manufactured by Nippon Kasei Co., Ltd.) was kneaded with an open roll at 50 ° C. for 0.5 hour (30 minutes), and a rubber compound (crosslinkable rubber composition, total 110) 0.5 parts by weight) was obtained.

  The rubber compound is filled in a mold, subjected to heat-crosslinking molding at a heating temperature of 160 ° C. for 15 minutes, then transferred to an electric furnace, heated, and subjected to secondary vulcanization at a heating temperature of 180 ° C. for 12 hours. Thus, a molded body (shape and dimensions: sheet shape, 2 × 100 × 180 mm) was obtained.

Using this vulcanized molded body (surface conductive rubber material) as a test sample and measuring the normal physical properties, surface specific resistance, and volume specific resistance under the above conditions,
Hardness (according to JIS-K6253, durometer type A at 25 ° C) is 75,
The tensile strength (conforming to JIS-K6251 at 25 ° C) is 32.1 MPa,
Elongation (conforms to JIS-K6251, 25 ° C) is 300%,
100% tensile stress (modulus, according to JIS K-6256) is 6.4 MPa,
The surface specific resistance (conforming to JIS K6911) is 10 ⁶ Ω or less (Range Over) when measured with a superinsulator, and 5.00 × 10 ⁴ Ω (“5.00E +” when measured with an automatic insulation resistance meter.
04 ". The same applies hereinafter. )

Further, the volume resistivity (based on JIS K6911) was 1.24 × 10 ¹¹ Ω · cm.
The results are also shown in Table 1.
[Examples 2-3]
In Example 1, a surface conductive rubber material (vulcanized molded body) was prepared in the same manner as in Example 1 except that the composition of the crosslinkable rubber composition was changed as shown in Table 1. Example 1 The same test was conducted.

The results are shown in Table 1.
[Comparative Example 1]
In Example 1, as shown in Table 1, 100 parts by weight of the same crosslinkable fluororubber,
Non-conductive filler ("Thermo Black MT", manufactured by (Cancarb) Co., Ltd.) 20 parts by weight,
1.5 parts by weight of the same crosslinking agent (“Perhexa 25B”),
4 parts by weight of the same co-crosslinking agent (“TAIC”) was kneaded with an open roll to obtain a rubber compound (125.5 parts by weight in total).

  This rubber compound is filled in a similar mold, heated (crosslinked) for 15 minutes at 160 ° C., and then subjected to secondary vulcanization in an electric furnace at 180 ° C. for 12 hours (hrs). Got the body.

About the obtained molded object, it carried out similarly to the said Example 1, and measured the normal physical property of the molded object, surface specific resistance, and volume specific resistance.
The results are shown in Table 1.
[Comparative Examples 2-3]
In Example 1, a rubber material (vulcanized molded product) was prepared in the same manner as in Example 1 except that the compounding component composition of the crosslinkable rubber composition was changed as shown in Table 1. A test was conducted.

The results are shown in Table 1.
[Comparative Example 4]
As shown in Table 1, 100 parts by weight of a crosslinkable fluororubber, 3 parts by weight of a conductive filler (trade name “Ketjen Black” (manufactured by (LION) Co., Ltd.), and the same crosslinking agent (“Perhexa 25B”) 1 0.5 parts by weight and 4.0 parts by weight of a co-crosslinking agent (“TAIC”) were kneaded with an open roll to obtain a rubber compound. This was filled in a mold, heated (crosslinked) for 15 minutes at 160 ° C., and then subjected to secondary vulcanization at 180 ° C. for 12 hours (hrs) in an electric furnace to obtain a molded body.

About the obtained molded object, it carried out similarly to the said Example 1, and measured the normal physical property of the molded object, surface specific resistance, and volume specific resistance.
The results are shown in Table 1.
[Comparative Examples 5-6]
In Example 1, a rubber material (vulcanized molded product) was prepared in the same manner as in Example 1 except that the compounding component composition of the crosslinkable rubber composition was changed as shown in Table 1. A test was conducted.

  The results are shown in Table 1.

FIG. 1 is a schematic diagram for explaining the arrangement of layered compounds and conductive fillers in a sheet-like conductive rubber material according to the present invention.

Claims (9)

A crosslinkable rubber composition containing a crosslinkable rubber, an organically treated layered compound, and a conductive filler is cross-linked, and has a surface resistivity of 10 ⁶ Ω or less and a volume resistivity of 10 ¹⁰ Ω.
A surface conductive rubber material characterized by being cm or more. (i) a crosslinkable rubber;
For 100 parts by weight of the rubber,
(ii) 2.0 to 15.0 parts by weight of an organically treated layered compound;
(iii) 3.0 to 10.0 parts by weight of conductive filler;
(iv) A crosslinkable rubber composition for a surface conductive rubber material, comprising a crosslinking agent.   The crosslinkable rubber composition for a surface conductive rubber material according to claim 2, wherein the layered compound (ii) is obtained by organically treating a layered inorganic compound with an ammonium salt.   A surface conductive rubber material obtained by crosslinking the crosslinkable rubber composition according to any one of claims 2 to 3. 5. The surface conductive rubber material according to claim 1, wherein the cross-linking treatment is a secondary vulcanization after the cross-linkable rubber composition is subjected to primary heat vulcanization molding. (ia) a crosslinked rubber;
For 100 parts by weight of the rubber,
(ii) 2.0 to 15.0 parts by weight of an organically treated layered compound;
(iii) 3.0 to 10.0 parts by weight of conductive filler;
A surface conductive rubber material comprising:   The surface conductive rubber material according to claim 6, wherein the layered compound (ii) is obtained by organically treating a layered inorganic compound with an ammonium salt. The surface conductive rubber material has a surface resistivity of 10 ⁶ Ω or less and a volume resistivity of 10 ¹⁰
The surface conductive rubber material according to any one of claims 4 to 7, which is Ω · cm or more.   An anti-static molded body made of only the surface conductive rubber material according to any one of claims 1 and 4 to 8, or comprising at least a part of the surface conductive rubber material.

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