TWI389978B - Insulating silicone rubber composition - Google Patents

Description

Insulating polyoxyethylene rubber composition

The present invention relates to a thermosetting polyoxyxene rubber composition, and particularly relates to an insulating polyoxyxene rubber composition which is excellent in antistatic properties not only at room temperature but also at a high temperature.

Polyoxymethylene rubber is widely used in various fields of electrical equipment, automobiles, construction, medical care, and food because of its excellent weather resistance, electrical properties, low compression set, heat resistance, and cold resistance. Such as: small keyboard used as a rubber contact for remote control, typewriter, word processor, computer terminal, musical instrument, etc.; construction gasket; anti-vibration rubber for audio device; connection seal, spark plug shield, etc. For use in automotive parts, CD pads for use in computers, bread, and molds for cakes. At present, the demand for polyoxyxene rubber is increasing, and it is expected to develop polyoxyxene rubber with better characteristics.

These polyoxyxene rubbers are usually supplied in the form of a composition containing a high degree of polymerization of an organopolyoxane and a reinforcing filler. This composition is adjusted by mixing a reinforcing filler and various dispersants in a raw material polymer using a mixing device such as a cartridge mixer or a double roller. If the reinforcing filler material such as organic polyoxane or cerium oxide is an electrical insulating material, the polyfluorene rubber composition obtained by blending the polyfluorene oxide rubber composition and the cured product thereof will generate static electricity after being contacted with various substances, resulting in static electricity. Adsorption of dust and other problems in the air.

In the prior art, the antistatic rubber is a polyether (Patent Document 1) and carbon black (Patent Documents 2 and 3) which are antistatic agents. When a polyether is used, the polyether is decomposed at a high temperature, and the problem of an effective antistatic effect cannot occur. In particular, only after the heat-curable polyoxyxene rubber is known to be treated, there is still no antistatic effect. When carbon black is used, it is difficult to maintain electrical insulation, and it is limited by the problem of black. Japanese Patent Laid-Open Publication No. 2003-82232 (Patent Document 4) discloses a polyoxyxene rubber composition for a semiconductive roller to which a lithium salt is added. However, in the semiconductor range, it cannot be applied to a wire covered with an insulating material. The existence of problems such as small keyboards.

[Patent Document 1] Japanese Laid-Open Patent Publication No. 2002-507240 (Patent Document 3) Japanese Laid-Open Patent Publication No. JP-A No. 2002- 277

An object of the present invention is to provide an insulating polyoxyxene rubber composition which is excellent in insulating properties and antistatic properties and which can maintain excellent antistatic properties even when exposed to high temperatures.

The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, it has been found that a small amount of an ion conductive antistatic agent is added to the thermosetting polyoxyxene rubber composition, and the above-mentioned lessons can be solved, and the present invention can be completed. In other words, the present invention provides an insulating polyoxyxene rubber composition having a good antistatic property of 0.0001 to 5 parts by mass of an ion conductive antistatic agent in 100 parts by mass of the thermosetting polyoxyxene rubber composition.

The cured product of the insulating polyoxyxene rubber composition of the present invention can maintain insulation properties, has good antistatic properties, and can maintain good antistatic properties when exposed to high temperatures. Also, you can freely color.

[Best form of implementation of the invention]

Hereinafter, the detailed description of the present invention will be made.

The composition of the thermosetting polyoxyxene rubber is not particularly limited as long as it is a composition of the polyoxyethylene rubber which is hardened by heat, and is generally organic having at least two alkenyl groups as a base polymer in the molecule. In the case of a polyoxyalkylene, if necessary, a filler such as a reinforcing cerium oxide is used, and an addition reaction type curing agent and/or an organic peroxide curing agent which is a curing agent are preferably used. The shape can be a milling cutter or a liquid form.

[(A) an organopolyoxane having at least two alkenyl groups in the molecule]

As the component (A), the following average composition formula (I) can be used.

RaSiO _{( 4 - 2 ) / 2} (I)

(wherein R is an unsubstituted or substituted monovalent hydrocarbon group having the same or different carbon number of 1 to 10, and a is a positive number of 1.8 to 2.3)

Wherein R is the same or different carbon number of 1 to 10, preferably 1 to 8 of an unsubstituted or substituted monovalent hydrocarbon group, specifically, for example, methyl, ethyl, propyl, isopropyl, butyl , isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, decyl, decyl, etc., alkyl having 1 to 10 carbon atoms, phenyl, tolyl, xylene An aryl group such as an aryl group having 6 to 10 carbon atoms, a benzyl group, a phenylethyl group or a phenylpropyl group, a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a butenyl group, or the like. Alkenyl, cyclohexenyl, octenyl and the like have 2 to 10 alkenyl groups, and some or all of the hydrogen atoms of these groups are replaced by a halogen atom such as fluorine, bromine or chlorine, a cyano group or the like, such as: Examples of chloropropyl, bromoethyl, trifluoropropyl, cyanoethyl and the like. Among these, methyl, vinyl, phenyl, and trifluoropropyl are preferred, and R is at least 50 mol% or more, and particularly preferably 80 mol% or more. In this case, at least two of R must be an alkenyl group (the carbon number is preferably 2 to 8, more preferably 2 to 6). The content of the alkenyl group is 0.0001 to 20 mol% in R, particularly preferably 0.001 to 10 mol%. The alkenyl group may be bonded to a ruthenium atom at the end of the molecular chain, or may be bonded to a ruthenium atom in the middle of the molecular chain, or may be bonded to both.

a is 1.8 to 2.3, preferably a positive number of 1.9 to 2.1. The organopolyoxane is substantially linear, but may be partially branched without detracting from the rubber elasticity. The molecular weight is not particularly limited. It is generally used in the form of a rubber having a low viscosity and a high viscosity. However, in order to harden the rubbery elastomer, the degree of polymerization is preferably from 100 to 100,000, particularly preferably from 150 to 20,000.

Further, the organopolyoxane of the component (A) may be one type or a combination of two or more different molecular structures or degrees of polymerization.

The organopolyoxane can be condensed by (co)hydrolysis by one or more of organic halogenated decane, or by cyclic or polyoxane using an alkaline or acidic catalyst via ring opening. Aggregated.

[Reinforcing cerium oxide]

The thermosetting polyoxyxene rubber composition is mechanically strong or the like, and therefore it is preferable to blend (B) a reinforcing cerium oxide with the organopolysiloxane of the component (A).

As (B) reinforcing cerium oxide, such as aerosolous cerium oxide, precipitated (wet) cerium oxide. These cerium oxides preferably have a specific surface area of 50 m ² /g or more in the BET method, and more preferably 100 to 400 m ² /g.

The cerium oxide may also have a surface treated with a surface treatment agent such as an organic polyoxyethylene rubber, a decane, a chlorosilane or an alkoxy decane, if necessary. Further, when the organic polysiloxane of the component (A) is blended with the fine powder of cerium oxide, the surface treating agent may be blended.

(B) The combination of the components may be any, and generally 100 parts by mass of the organopolyoxane of the component (A) is preferably 0 to 100 parts by mass, preferably 1 to 80 parts by mass, particularly 5 ~50 parts by mass. If the amount is too small, sufficient rubber strength will not be obtained. Further, when a rubber is processed using a raw rubber as a raw material, the workability may be lowered. Moreover, when the amount of the mixture is too large, it may be difficult to mix, and the rubber property may be lowered.

The thermosetting polyoxyxene rubber composition may be optionally added with a filler such as pulverized quartz, crystalline cerium oxide, diatomaceous earth, calcium carbonate, or the like, in addition to the above components, without damaging the scope of the present application. Agent, lifting tensile strength agent, heat-resistant agent such as iron oxide or cerium oxide, flame retardant agent such as titanium oxide and platinum compound, acid resistance agent, thermal conductivity agent for lifting alumina, boron nitride, etc. Various alkoxydecanes for dispersants, especially phenyl-containing alkoxydecanes and hydrolyzates thereof, diphenyldecanediol, carbon functional decane, fluorenyl-containing low molecular oxiranes, etc. A known filler or additive in the thermosetting polyoxyxene rubber composition.

[hardener

(C) Hardener: For example, the above (C-1) addition reaction type hardener and (C-2) organic peroxide hardener.

As the (C-1) addition reaction type hardener, an organic hydrogenated polyoxyalkylene and a hydrosilation catalyst can be used in combination.

The hydroformylation catalyst is a catalyst for subjecting an alkenyl group of the component (A) to a hydrogen atom (SiH group) bonded to a ruthenium atom of an organohydrogenated polyoxyalkylene oxide.

As the hydroformylation catalyst, for example, a platinum metal catalyst, a platinum group metal monomer, and a compound thereof can be used as an addition reaction hardening type polyoxyethylene rubber composition, which is known in the prior art. Catalyst. For example, a particulate platinum metal adsorbed on a carrier of cerium oxide, aluminum oxide or cerium oxide gel, platinum chloride, chloroplatinic acid, chloroplatinic acid 6 molybdenum alcohol solution, palladium catalyst, ruthenium In the case of a catalyst or the like, platinum or a platinum compound is preferred. The addition amount of the catalyst may be such that the addition reaction can be promoted, and it is usually 10 to 500 pppm in terms of the amount of the platinum metal, and the amount of the organopolysiloxane of the component (A) is from 1 to 1% by weight. When the addition amount is less than 1 ppm, the addition reaction will not be effectively promoted, and insufficient hardening will occur. On the contrary, if it exceeds 1% by weight, a large amount will still have no influence on the reactivity, and it is not economical.

As the organic hydrogenated polyoxyalkylene, as long as one molecule contains two or more, preferably three or more SiH groups, it may be linear, branched or cyclic, and is used as an addition reaction. As the crosslinking agent of the thermosetting polyoxyethylene rubber composition, a known organic hydrogenated polyoxyalkylene can be used. For example, an organic hydrogenated polyoxyalkylene represented by the following average composition formula (II) can be used.

R ¹ _p H _q SiO _{( 4 - p . q ) / 2} (II)

In the above average composition formula (II), R1 represents an unsubstituted or substituted one-valent hydrocarbon group, which may be the same or different, and preferably does not contain an aliphatic unsaturated bond. Generally, the carbon number is preferably from 1 to 12, particularly preferably from 1 to 8. Specifically, for example, an alkyl group such as a methyl group, an ethyl group or a propyl group, a cycloalkyl group such as a cyclohexyl group, a vinyl group, an allyl group, or the like. An alkenyl group such as a butenyl group or a hexenyl group; an aryl group such as a phenyl group or a tolyl group; an aralkyl group such as a benzyl group, a 2-phenylethyl group or a 2-phenylpropyl group; and a part of such a group or A group in which all hydrogen atoms are replaced by a halogen atom or the like, such as a 3,3,3-trifluoropropyl group. Further, p, q satisfy 0 ≦ p < 3, preferably 1 ≦ p ≦ 2.2, 0 < q ≦ 3, preferably 0.002 ≦ q ≦ 1, 0 < p + q ≦ 3, preferably 1.002正p+q≦3 is a positive number.

The organic hydrogenated polyoxyalkylene system has two or more molecules, preferably three or more SiH groups, and this may be at the end of the molecular chain, in the middle of the molecular chain, or both. Further, as the organic hydrogenated polyoxyalkylene, the viscosity at 25 ° C is preferably 0.5 to 10,000 cSt, particularly preferably 1 to 300 cSt.

As a specific example of the organic hydrogenated polyoxyalkylene, the compound of the following structural formula can be exemplified.

(where k is an integer from 2 to 10, and s and t are integers from 0 to 10)

The amount of the above organic oxoxane is preferably 0.1 to 40 parts by weight based on 100 parts by weight of the component (A). Further, in the case of one of the aliphatic unsaturated bonds (alkenyl group and dienyl group) of the component (A), the ratio of the hydrogen atom (≡SiH group) bonded to the ruthenium atom is preferably in the range of 0.5 to 10, more preferably Good range of 0.7~5. When it is less than 0.5, the crosslinking is insufficient, and sufficient mechanical strength cannot be obtained. On the contrary, if it exceeds 10, the physical properties after hardening are lowered, particularly, the deterioration of heat resistance and permanent compression deformation is caused.

Further, in addition to the above-mentioned catalyst, an addition-crosslinking inhibitor may be used for the purpose of adjusting the curing rate. Specific examples thereof include an acetylene alcohol-based inhibitor such as acetylene cyclohexanol and a tetracyclomethylethylene polyoxane.

As (C-2) organic peroxides such as: benzamidine peroxide, 2,4-dichlorobenzamide peroxide, p-methylbenzamide peroxide, o-methyl Benzamidine peroxide, 2,4-dicumyl peroxide, 2,5-dimethyl-bis(2,5-tri-butyl peroxide) hexane, di-third-butyl Base peroxide, tri-butyl perbenzoate, 1,6-hexanediol-bis-tert-butyl percarbonate, and the like.

The amount of the organic peroxide added is preferably from 0.1 to 10 parts by weight, particularly preferably from 0.2 to 5 parts by weight, per 100 parts by weight of the component (A).

The thermosetting polyoxyxene rubber composition can be obtained by mixing the above components with a known kneader such as a kneader, a Banbury-type high-speed mixer, or a twin roll, and generally, mixing the organic polymerization of the component (A). It is preferred to add a hardener of the component (C) after the cerium oxide and the reinforcing cerium oxide of the component (B).

Commercially available products can also be used as the thermosetting polyoxyxene rubber composition.

The ion conductive antistatic agent contained in the insulating polyoxyethylene rubber composition of the present application is not particularly limited as long as it is not an electron conductive material of carbon black type but an ion conductive material, and a lithium salt is generally preferred.

Specifically, for example, LiBF ₄ , LiClO ₄ , LiPF ₆ , LiAsF ₆ , LiSbF ₆ , LiSO ₃ CF ₃ , LiN(SO ₂ CF ₃ ) ₂ , LiSO ₃ C ₄ F ₉ , LiC(SO ₂ CF ₃ ) ₃ , LiB ( Examples such as C ₆ H ₅ ) ₄ . These may be used alone or in combination of two or more.

The ion-conductive antistatic agent exhibits a stabilizing effect in order to improve the dispersibility in the thermosetting polyoxyxene rubber composition, and it is preferable to gelatinize the organopolysiloxane. At this time, the organopolyoxyalkylene is the same as or different from the component (A), and may be in the form of a raw rubber or oil. Preferred is dimethyl polyoxyalkylene or methyl vinyl polyoxyalkylene. Further, in the case of gelatinization, a filler such as reinforcing cerium oxide or diatomaceous earth may be added in order to improve workability. The concentration of the ion conductive antistatic agent in the gelatinization is preferably from 2 to 90% by mass, preferably from 5 to 80% by mass, particularly preferably from 10 to 50% by mass.

The amount of the ion-conductive antistatic agent to be added is preferably 0.0001 to 5 parts by mass, more preferably 0.0005 to 3 parts by mass, more preferably 0.001 to 1 part by mass for 100 parts by mass of the thermosetting polyoxyxene rubber composition. The portion is particularly preferably 0.001 to 0.5 parts by mass. When the amount is less than 0.0001 part by mass, the antistatic effect will be insufficient. On the other hand, if it is more than 5 parts by mass, the insulating property cannot be maintained, and the physical properties of the polyoxyxene rubber, heat resistance and the like are adversely affected.

The ionic antistatic agent may be added to the thermosetting polyoxymethylene rubber composition or may be added to the heat conductive polyoxymethylene rubber composition.

The insulating polyoxyxene rubber composition of the present invention is a polyoxyxene rubber which is excellent in insulation by heat curing. As the molding method, a method of injection molding, compression molding, injection molding, calender molding, extrusion molding, coating, screen printing, or the like is selected. As a curing condition, a known condition of the molding method may be used, and usually, it is at a temperature of 60 ° C to 450 ° C for several seconds to one day. Further, in order to reduce the compression set of the cured product, to lower the low molecular weight polyoxane component remaining in the polyoxyxene rubber, or to remove the decomposition product of the organic peroxide, the temperature is 200 ° C or higher, preferably The oven of 200 ° C to 250 ° C may be used for 1 hour or longer, preferably 1 hour to 70 hours, and more preferably 1 hour to 10 hours, and then hardened (2 times hardened).

The volume resistivity of the hardened material is 1G Ω. More than m, especially 2G Ω. When the m or more is good, the wire is covered, and the small keyboard is used, the insulation level can be fully utilized.

Further, as an antistatic property, an electrostatic function meter (CCDO Electrostatic Gas (manufactured by CCTV)) was used to make a static electricity gas into a 6 kV feed via a corona discharge on a surface of a polyoxyethylene rubber molded article, and the static voltage was half time ( The half-life is preferably within 2 minutes, particularly within 1 minute.

[Examples]

Hereinafter, the present invention will be specifically described by way of examples and comparative examples, but the present invention is not limited to the following examples.

The amount of static electricity and the volume resistance were measured by the following methods.

[Static measurement]

An electrostatic function meter (CCDO static electricity (manufactured by CO., Ltd.) was used, and after the electrostatic charge was applied to the surface of the molded article via corona discharge, the static voltage was measured for half of the time.

[Volume resistance measurement]

It is measured based on JIS-K6249.

The antistatic agent is gelatinized as described below.

[Adjustment of antistatic agent gelatinization]

42 parts by mass of a dimethylpolyoxane raw rubber terminated with a dimethyl oxiranyl group and a hydrophobized tourmaline having a specific surface area of 110 m ² /g (R-972, Japan Aerozil) 50 parts by mass of 20% by mass of adipate of LiN(SO ₂ CF ₃ ) ₂ was kneaded to prepare an antistatic agent paste 1.

The antistatic agent is a hydrophobized tourmaline (R) having a specific surface area of 110 m ² /g, which is 42 parts by mass of a dimethylpolyoxane raw rubber which is terminated with a dimethyl oxiranyl group. - 972, an antistatic agent paste 2 was prepared by dissolving 50 parts by weight of a polyether modified polysiloxane (KF351F Shin-Etsu Chemical Co., Ltd.) having a viscosity of 75 cs at a temperature of 25 ° C in an amount of 8 parts by mass.

[Example 1]

Adding dimethyl methoxyoxane unit 99.825 mol%, methyl vinyl siloxane unit 0.15 mol%, dimethyl vinyl fluorene unit 0.025 mol%, organic polymerization with an average degree of polymerization of about 6000 100 parts by mass of oxyalkylene and 45 parts by mass of a BET specific surface area of 200 m ² /g (Aerozil 200 Japan Aerozil Co., Ltd.), as a dispersing agent, having both terminal stanol groups and an average degree of polymerization of 15, 25 10 parts by mass of 30 Cs of dimethyl polyoxane at a viscosity of ° C, and kneading was carried out in a kneader, and heat treatment was performed at 170 ° C for 2 hours to prepare a composition.

To 100 parts by mass of the composition, 0.05 parts by mass of the antistatic agent paste 1 and 0.4 parts by mass of 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane as a crosslinking agent were added. Then, the mixture was uniformly mixed by a double roll, and then press-hardened for 10 minutes at 165 ° C under a condition of 70 kgf / cm ^{2 to} prepare a sheet having a thickness of 2 mm. The post-hardening was carried out in an oven at 200 ° C for 4 hours.

The polyoxyxene rubber was returned to room temperature, and the amount of static electricity (half-life) and volume resistance were measured. Similarly, the amount of static electricity and volume resistance were measured for 50 hours, 100 hours, and 400 hours in a 200 ° C oven.

The results are shown in Table 1.

[Embodiment 2]

The amount of static electricity and volume resistance were measured in the same manner as in Example 1 except that the amount of the antistatic agent paste 1 added was 0.01 parts by mass.

The results are shown in Table 1.

[Example 3]

The diorganotoxioxane unit of the main chain of the molecular chain contains methyl methoxide unit 10 mol% and dimethyl methoxy oxane unit 90 mol%, and the viscosity is 500 mPa. The dimethyl group of s is terminated with a trimethyl methoxyalkyl group at both ends of the molecular chain. Hydrophobized tourmaline (R-972 Japan Aerozil Co., Ltd.) 5 parts by mass, crystalline ceria (crysterlite Vx), 100 parts by mass of a methylvinyl siloxane copolymer and a specific surface area of 110 m ² /g -S Longsen (share) system) 38 parts by mass, viscosity 9mPa. a dimethyl methoxyoxane having a SiH group at both ends of the molecular chain of s and a non-terminal end of the molecular chain, a methyl hydride hydride copolymer (a hydrogen atom bonded to a ruthenium atom: 0.51% by mass), 1.5 parts, 1-acetylene 0.03 parts of cyclohexanol, a complex of chloroplatinic acid and diethylenetetramethyldioxane in terms of mass of platinum metal, dimethyl group terminated with trimethylphosphonyl group at both ends of the molecular chain Hexane. The composition was prepared by adding 15 ppm of methylvinyl siloxane copolymer.

To 100 parts by weight of the composition, 0.1 part by weight of the antistatic agent paste 1 was added, and press hardening was carried out for 10 minutes at 120 ° C and 100 kgf / cm ² . The post-hardening was carried out in an oven at 200 ° C for 4 hours.

The polyoxyxene rubber was returned to room temperature, and the amount of static electricity (half-life) and volume resistance were measured. The amount of static electricity and volume resistance were measured in the oven at 200 ° C for 50 hours, 100 hours, and 400 hours.

The results are shown in Table 1.

[Example 4]

The amount of static electricity and the volume resistance were measured in the same manner as in Example 3 except that the antistatic agent paste 1 was made into 0.05 part by weight. The results are shown in Table 1.

[Comparative Example 1]

The amount of static electricity and the volume resistance were measured in the same manner as in Example 1 except that the antistatic agent was not added.

The results are shown in Table 1.

[Comparative Example 2]

The amount of static electricity and volume resistance were measured in the same manner as in Example 1 except that the antistatic agent paste 2 was used instead of the antistatic agent paste 1.

The results are shown in Table 1.

[Comparative Example 3]

The amount of static electricity and volume resistance were measured in the same manner as in Example 3 except that the antistatic agent was not added.

The results are shown in Table 1.

(1.2E+12 stands for 1.2×10 ^{1 2} )

Claims (7)

An insulating polyoxyxene rubber composition having good antistatic property, characterized in that it contains an ion conductive antistatic agent of 0.0001 to 0.01 parts by mass for 100 parts by mass of the thermosetting polyoxyxene rubber composition; The polyoxyxene rubber composition is an addition-hardening type or an organic peroxide-curing type thermosetting type polysulfide rubber composition composed of the following (A) to (C), (A) the following average An organopolyoxane having at least two alkenyl groups bonded to a ruthenium atom in the molecule represented by the formula (I): 100 parts by mass of R _a SiO _(4-a) /2 (I) (wherein R is an unsubstituted or unsubstituted carbon number of 1 to 10 or a monovalent hydrocarbon group substituted by a halogen atom or a cyano group, a is a positive number of 1.8 to 2.3, and (B) a reinforcing cerium oxide: 0 to 100 a mass fraction, and (C) a hardener; the ion conductive antistatic agent is a lithium salt gelatinized with an organic polyoxane and an adipate; the volume resistivity of the cured product is 2.5×10 ¹¹ to 1.3× 10 ¹³ Ω. Cm. The insulating polyoxyxene rubber composition according to claim 1, wherein the component (B) is selected from the group consisting of aerosol-type cerium oxide having a BET specific surface area of 50 to 400 m ² /g and precipitated cerium oxide. An insulating polyoxyxene rubber composition according to claim 1, wherein the component (C) is (C-1) from an organohydrogenpolysiloxane and a hydrogenation catalyst. An additive anti-hardening hardener composed of a combination. An insulating polyoxymethylene rubber composition according to claim 1, wherein the component (C) is (C-2) an organic peroxide hardener. The insulating polyoxyxene rubber composition according to claim 1, wherein the ion conductive antistatic agent is selected from the group consisting of LiBF ₄ , LiClO ₄ , LiPF ₆ , LiAsF ₆ , LiSbF ₆ , LiSO ₃ CF ₃ , LiN ( One or two or more of SO ₂ CF ₃ ) ₂ , LiSO ₃ C ₄ F ₉ , LiC(SO ₂ CF ₃ ) ₃ , and LiB(C ₆ H ₅ ) ₄ . A cured product obtained by hardening an insulating polyoxyxene rubber composition according to any one of claims 1 to 5. A cured product of the composition of the insulating polyoxyxene rubber composition according to any one of claims 1 to 5, which is cured at 200 ° C or higher and then cured for 1 hour or longer.