JP3235434B2 - Semiconductive silicone elastomer composition and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-curable semiconductive silicone elastomer composition which is cured by a hydrosilylation reaction and a method for producing the same, and more particularly, to a region having a volume resistivity of 10 ⁵ to 10 ¹⁰ Ω · cm. The present invention relates to a semiconductive silicone elastomer composition which provides a semiconductive silicone elastomer having a stable semiconductive property and a small variation in volume resistivity, and a method for producing the same.

[0002]

BACKGROUND OF THE INVENTION Silicone rubber is used in many fields as an electrically insulating rubber because of its excellent heat resistance, cold resistance, weather resistance and electrical insulation. When imparting conductivity to the silicone rubber, π-electron transfer type conductive substances such as carbon black, graphite powder, carbon fiber, silver, nickel, copper, zinc, iron, gold, silicon, etc. A free electron transfer type conductive substance such as metal powder or metal flake, a compound represented by an oxide such as the above metal, or the like can be used, and the silicone elastomer composition to which these are added is widely used as a conductive silicone elastomer composition. Used in the field.

However, a semiconductive silicone elastomer having a volume resistivity of 10 ⁵ to 10 ¹⁰ Ω · cm, which is a semiconductive region, and having a small variation in this value has not been obtained so far. The semiconductive silicone elastomer having the above volume resistivity can be obtained, for example, by adjusting the amount of conductive carbon black added.
There is a problem that the volume resistivity varies when the silicone elastomer composition is molded.

Japanese Patent Application Laid-Open No. Sho 63-156858 proposes a method of blending a crosslinked silicone rubber pulverized product containing carbon black with a silicone rubber composition. The diameter is 0.
Since it is as large as 3 mm, when it is added to a liquid silicone elastomer composition, the dispersibility is poor, and it is difficult to obtain a silicone elastomer having a small variation in volume resistivity.

[0005] The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a semiconductive silicone elastomer composition in which a conductive substance is satisfactorily and uniformly dispersed in a silicone elastomer to give a semiconductive silicone elastomer having a small variation in volume resistivity, and a method for producing the same.

[0006]

Means for Solving the Problems and Embodiments of the Invention The present inventors have conducted intensive studies in order to achieve the above object, and as a result, have found that an aliphatic unsaturated hydrocarbon group bonded to a silicon atom in one molecule is two or more. At least one organopolysiloxane, and 1
When producing a semiconductive silicone elastomer composition containing an organohydrogenpolysiloxane containing two or more hydrogen atoms bonded to silicon atoms in a molecule and a conductive material, conductive carbon 1 is used as the conductive material. ~
A conductive filler other than conductive carbon having a volume resistivity of 10 ¹ to 10 ⁸ Ω · cm and a weight of 10 to 90% by weight.
And using the conductive material in an amount of 20 to 60% by weight of the entire composition. In this case, when the composition further contains a non-conductive inorganic filler, the conductive material contains It has been found that it is effective to set the amount to be 50 to 80% by weight of the total amount of the conductive substance and the inorganic filler. After kneading a part or all of an organopolysiloxane containing two or more group-unsaturated hydrocarbon groups and conductive carbon under heating at 100 to 200 ° C, the mixture is cooled to room temperature, and then cooled to 10 ^1. -10 ⁸ Ω
By adding a conductive filler other than conductive carbon having a specific volume resistivity of 0.5 cm and remixing at 0 to 60 ° C., the volume resistivity distribution is in the range of 10 ⁵ to 10 ¹⁰ Ω · cm. (Volume resistivity distribution means the ratio between the maximum value and the minimum value of the volume resistivity of the semiconductive silicone elastomer), and it has been found that the present invention provides a semiconductive silicone elastomer having 1 to 10. It is something that has been done.

Accordingly, the present invention provides an organopolysiloxane containing two or more aliphatically unsaturated hydrocarbon groups bonded to silicon atoms in one molecule, and two hydrogen atoms bonded to silicon atoms in one molecule. In the semiconductive silicone elastomer composition containing the organohydrogenpolysiloxane containing the above and a conductive substance, the conductive substance is
1 to 10% by weight of conductive carbon and a volume resistivity of 10
^1-10 together consist ⁸ Omega · cm-conductive filler 90 to 99% by weight of non-carbon and the constituted by the conductive material is blended 20-60% by weight of the total composition, 10 ⁵
A semiconductive silicone elastomer composition which provides a semiconductive silicone elastomer having a volume resistivity distribution of 1 to 10 within a range of 10 to 10 ¹⁰ Ω · cm; and a bond with a silicon atom in one molecule. 100 to 200 parts or all of the organopolysiloxane containing two or more aliphatic unsaturated hydrocarbon groups and all of the conductive carbon.
After kneading under heating at a temperature of room temperature (for example, 0 to 40).
° C), and then add all the conductive fillers other than conductive carbon having a volume resistivity of 10 ¹ to 10 ⁸ Ω · cm, and remix at 0 to 60 ° C to obtain a base compound. Producing said semiconductive silicone and then adding to said base compound an organohydrogenpolysiloxane containing the remainder of said organopolysiloxane and at least two hydrogen atoms bonded to silicon atoms in one molecule. Provided is a method for producing an elastomer composition.

Hereinafter, the present invention will be described in more detail. The semiconductive silicone elastomer composition of the present invention comprises (A)
An organopolysiloxane containing two or more aliphatic unsaturated hydrocarbon groups bonded to a silicon atom in one molecule, (B) 1
A conductive filler other than an organohydrogenpolysiloxane containing two or more hydrogen atoms bonded to silicon atoms in the molecule, (C) conductive carbon, and (D) conductive carbon; 10 ¹ to 10 ⁸ Ω · cm Containing a specific volume resistivity value of

Here, the organopolysiloxane containing two or more aliphatic unsaturated hydrocarbon groups bonded to silicon atoms in the molecule of the component (A) serves as a main component of the silicone elastomer composition of the present invention. It is. As this organopolysiloxane, ^one having an average composition formula represented by R ¹ _a SiO _{(4-a) / 2} is used. In this formula, R ¹ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and at least two of R ¹ are aliphatically unsaturated hydrocarbon groups. In this case, examples of the unsaturated hydrocarbon group include alkenyl groups such as a vinyl group, an allyl group, and an isopropenyl group. Examples of the organic group R ¹ other than the unsaturated hydrocarbon group include an alkyl group such as a methyl group, an ethyl group, a propyl group and a butyl group, an aryl group such as a phenyl group and a tolyl group, and a hydrogen atom of these organic groups. Examples thereof include a chloromethyl group, a trifluoromethyl group, a cyanoethyl group, and the like, in which a part or all of is substituted with a halogen atom or a cyano group. A is 1 to 3, preferably 1.9.
It is a positive number of ２．１2.1.

The structure of the organopolysiloxane is preferably linear, but may have a partially branched or cyclic skeleton. The viscosity of this organopolysiloxane at 25 ° C. is preferably 200 to 200,000 centistokes (cs), particularly preferably 100 to 100,000 cs.

On the other hand, an organohydrogenpolysiloxane having two or more hydrogen atoms (ie, SiH groups) bonded to silicon atoms in the molecule of the component (B) is used as a crosslinking agent for the organopolysiloxane of the component (A). Component. Those organic groups bonded to the silicon atoms other than hydrogen atoms the same as the organic group R ¹ in the component (A), preferably include those that do not have aliphatic unsaturated bonds, known organo as this thing Hydrogen polysiloxane can be used.

The structure of the organohydrogenpolysiloxane of the component (B) is generally linear, but it may have a branched, cyclic or three-dimensional network skeleton. Further, the degree of polymerization (the number of silicon atoms in the molecule) is preferably from 3 to 300.

The amount of component (B) is such that the molar ratio of hydrogen atoms bonded to silicon atoms in component (B) to aliphatic unsaturated hydrocarbon groups bonded to silicon atoms in component (A) is 10: 1. ~
The amount is preferably in the range of 1:10, preferably 3: 1 to 1: 3.

Further, a catalytic amount of a hydrosilylation reaction catalyst such as a platinum compound, a rhodium compound or a palladium compound is usually added to the composition of the present invention.

As the platinum or platinum-based compound, known compounds can be used, and specifically, platinum black, chloroplatinic acid,
Examples include alcohol-modified chloroplatinic acid, and complexes of chloroplatinic acid with olefins, aldehydes, vinylsiloxanes, acetylene alcohols, and the like.

The amount of platinum or a platinum-based compound, rhodium compound, or palladium compound can be appropriately increased or decreased in accordance with the desired curing rate by a catalytic amount. 0.1 to 1000 ppm, especially 1 to 50 ppm in terms of amount, rhodium amount or palladium amount.
It is preferable to set the range to 0 ppm.

The semiconductive silicone elastomer composition of the present invention contains a conductive substance. In the present invention, the conductive substance has (C) a volume resistivity of 10 ¹ Ω · A combination of a conductive carbon having a diameter of less than cm and a conductive filler other than the conductive carbon (D) is used.

In this case, the conductive carbon of the component (C) is not particularly limited, and may be any of commonly used carbon blacks such as graphites, acetylene black, oil furnace black and anthracene black. One of these may be used alone, or two or more of them may be used in combination. In particular, acetylene black, oil furnace black and the like are preferably used.

On the other hand, as the conductive filler other than the conductive carbon of the component (D), the volume specific resistance is 10 ¹ to 1.
To use one of the 0 ⁸ Ω · cm. Specific examples of such conductive fillers include conductive zinc white, titanium black, black iron oxide, tin oxide, metal oxides such as antimony oxide, germanium, and other metal types such as magnetite powder. Among them, metal oxides are particularly preferably used. These conductive fillers can be used alone or in combination of two or more.

Here, the compounding amount of the conductive substance (conductive carbon and conductive filler) is 20 to 20% of the whole composition.
60% (% by weight, hereinafter the same). If less than 20%, the resulting silicone elastomer is an insulating elastomer (ie, one having a volume resistivity of more than 10 ¹⁰ Ω · cm)
When more than 60%, the conductive elastomer (ie,
However, there is a disadvantage that the volume resistivity is less than 10 ⁵ Ω · cm.

The proportion of the above components (C) and (D) is 1 to 10%, preferably 2 to 7%, and 90% for the former.
To 99%, more preferably 93 to 98%. (D)
When the proportion of the component is less than 90%, the silicone elastomer becomes conductive.
Since it is difficult to obtain a semiconductivity of 0 ⁵ to 10 ¹⁰ Ω · cm, the object of the present invention cannot be achieved.

When a non-conductive inorganic filler having a volume resistivity of more than 10 ⁸ Ω · cm, such as silica fine powder described later, is added to the composition of the present invention, the amount of the component (D) is set to 50 to 80 of the total amount of the active substance and the inorganic filler
It is preferable to set the weight%. (D) The amount of the component is 5
If the amount is less than 0% by weight, it is difficult to sufficiently exhibit semiconductivity. If the amount exceeds 80% by weight, there is a case where a problem that the reinforcing property of the silicone elastomer is reduced and the strength of the silicone elastomer itself is reduced is caused.

If necessary, the silicone elastomer composition of the present invention may further contain a non-conductive inorganic filler such as silica fine powder or calcium carbonate as described above in an amount of 100 parts by weight of the organopolysiloxane (A). 0 to 200 parts, more preferably 5 to 100 parts, even more preferably 10 to 80 parts per 1).

Also, nitrogen-containing compounds, acetylene compounds, phosphorus compounds, nitrile compounds, carboxylates,
It is optional to add a hydrosilylation reaction control agent such as a tin compound, a mercury compound, or a sulfur compound, a heat-resistant agent such as iron oxide or cerium oxide, an adhesion-imparting agent, or a thixotropic agent.

In order to produce the semiconductive silicone elastomer composition of the present invention, first, a part or all of the organopolysiloxane (A) and the conductive carbon (C) are mixed. Heat to 200 ° C. and knead. In this case, the kneading time can be 1 to 5 hours. After completion of kneading, room temperature (normally 0 to 40 ° C, particularly 5 to
(30 ° C.), then the component (D) is added, and the mixture is further kneaded at 0 to 50 ° C. for 1 to 5 hours to obtain a base compound. A semiconductive silicone elastomer composition can be obtained by adding the remainder of the component (A), the organohydrogensiloxane of the component (B), and a hydrosilylation reaction catalyst to the base compound thus obtained.

That is, in the compounding amounts of the components (C) and (D), the conductive carbon of the component (C) and the conductive filler of the component (D) are simultaneously added to part or all of the component (A). When added and subjected to a heat treatment at 100 to 200 ° C., the resulting silicone elastomer becomes a material having a volume resistivity of the insulating region, that is, a volume resistivity exceeding 10 ¹⁰ Ω · cm. The resulting silicone elastomer has a volume resistivity of the conductive region, that is, 10 ⁵ Ω.
-The material has a volume resistivity smaller than cm. Further, it is difficult to stabilize the distribution of the volume resistivity widely by these methods. In contrast, the (C), (D) a portion of either of the components of the component (A) or the whole and kneading, by heat treatment, 10 ⁵ to 1
A silicone elastomer having a semiconductivity of 0 ¹⁰ Ω · cm is obtained. In this case, the conductive carbon of the component (C) is heat-treated with a part or all of the component (A),
It is recommended to adopt the above-described method because the variation of the volume resistivity is smaller and can be stabilized, and the volume resistivity distribution can be in the range of 1 to 10, particularly 2 to 5.

Here, in the present invention, the volume resistivity distribution means the ratio of the maximum value to the minimum value of the measured volume resistivity of the cured silicone elastomer, and this measured value is the same for the same cured product. It is desirable to measure at least 10 or more at different locations of the product, or at least 10 or more cured products cured under the same composition and curing conditions.

When a part of the component (A) is kneaded with the component (C), it is preferable to use 10 to 90% of the component (A). When the non-conductive inorganic filler is blended, it may be blended with the component (C) or with the component (D).

When the semiconductive silicone elastomer composition is cured, the composition is heated at 60 to 200 ° C. for 1 to 20 minutes, and after primary vulcanization such as press molding, if necessary, 150 ° C.
A method of secondary vulcanization at ~ 250 ° C for 2-7 hours may be employed.

The obtained silicone elastomer has 10
^It has a semiconductivity of ⁵ to 10 ¹⁰ Ω · cm, and has a very small volume resistivity distribution in this range, and is stable at 1 to 10. For this reason, the semiconductive silicone elastomer composition of the present invention is suitably used for applications such as a paper feed roller, a transfer roller, a developing roller, and a fixing roller for preventing paper wrapping such as a PPC, a printer, and a facsimile.

[0031]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

In the following example, the volume resistivity is
It was measured by the following method according to the Japan Rubber Association Standard Standard SRIS 2301-1969. In addition, rubber hardness (JIS
A hardness meter), tensile strength, elongation, compression set are JI
The measurement was performed according to the method described in SK-6301. As shown in FIG. 1, a test piece 1 having a length of 150 mm, a width of 20 mm, and a thickness of 0.5 to 1.0 mm is sandwiched between an upper electrode 2 and a lower electrode 3. The upper electrode 2 has a length of 30 mm and a width of 15 m
A pair of current terminals 2a, 2a having a thickness of 5 mm and a thickness of 5 mm are attached to an insulator 4 such as polyethylene, and a weight 5 is placed thereon so that a weight of 5 kg is applied to the current terminals 2a, 2a. On the other hand, the lower electrode 3 has a length of 30 mm and a width of 15 m
m, a pair of current terminals 3a, 3a having a thickness of 5 mm and a length of 30
mm, 5 mm wide pair of knife-shaped voltage terminals 3b, 3b
These current terminals 3a, 3a are arranged so as to face the current terminals 2a, 2a of the upper electrode 2. On the test piece 1, 0.5
A weight 7 of kg is placed, and the lower electrode 3 is set on an insulating plate 8. In this state, the upper electrode 2 and the lower electrode 3 are connected, and the volume resistivity is measured.

[Example 1] Carbon black (Ketjen Black EC-600JD, Lion Akzo Co., Ltd.)
1.2 g, a linear dimethylpolysiloxane containing (CH ₂ ＣＨCH) (CH ₃ ) SiO _2/2 units and having both ends capped with a trimethylsilyl group (viscosity 10,000 cs, vinyl group equivalent 0.0094 mol / 100 g) 60 g and crystalline silica 30 g were kneaded at 150 ° C. for 2 hours. Then 2
Cool to 5 ° C and add conductive zinc white (volume resistivity 60Ω)
・ Cm (under a pressure of 570 kg / cm ² )), and after mixing, the mixture was uniformly dispersed with three rolls at 25 ° C. to obtain a base compound A.

The base compound A is shown in Table 1.
The ingredients were blended in the amounts shown in Table 1 at 120 ° C. and 100 kg / c.
m^Two Press vulcanization at 200 ° C for 4 minutes 2
Next vulcanization, a total of 10 silicone elastomer sheets
The sheets were manufactured and the volume resistivity of these sheets was measured. The result
Also shown in Table 1.

[Example 2] Titanium black (volume specific resistance 90Ω ·
cm (under a pressure of 570 kg / cm ² )), 10 base compounds B and 10 silicone elastomer sheets were produced in the same manner as in Example 1, and the volume resistivity was measured. The results are also shown in Table 1.

Comparative Example 1 2.5 g of carbon black
60 g of the same vinyl group-containing dimethylpolysiloxane and 90 g of crystalline silica as used in Example 1 were kneaded at 150 ° C. for 2 hours, and then uniformly dispersed with three rolls at 25 ° C. to produce a base compound C. .

The base compound C was mixed with the substances shown in Table 1 and vulcanized under the same conditions as in Example 1 to produce 10 silicone elastomer sheets. The volume resistivity was measured in the same manner as in Example 1. did. The results are also shown in Table 1.

[Comparative Example 2] All the raw materials of the base compound A in Example 1 were mixed, and 1
The mixture was kneaded for 2 hours under heating at 50 ° C. to produce a base compound D. Ten sheets were produced in the same manner as in Example 1, and the volume resistivity was measured. The results are also shown in Table 1.

[Comparative Example 3] All the raw materials of the base compound A in Example 1 were kneaded at 25 ° C without heating.
Base compound E was manufactured, ten sheets were manufactured in the same manner as in Example 1, and the volume resistivity was measured. The results are also shown in Table 1.

[0040]

[Table 1]

[0041]

According to the present invention, it is possible to obtain a semiconductive silicone elastomer composition in which a conductive substance is satisfactorily and uniformly dispersed in a silicone elastomer to give a semiconductive silicone elastomer having a small variation in volume resistivity. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a method for measuring volume resistivity.

[Explanation of symbols]

 1 Test piece 2 Upper electrode 3 Lower electrode

Continuation of the front page (72) Inventor Kazuto Saito 1-10 Hitomi, Matsuida-cho, Usui-gun, Gunma Prefecture Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory (56) References (58) Investigated field (Int.Cl. ⁷ , DB name) C08L 83/07 C08K 3/00 C08K 3/10 C08K 7/04 C08L 83/05

Claims (4)

(57) [Claims] 1. An organopolysiloxane containing two or more aliphatic unsaturated hydrocarbon groups bonded to a silicon atom in one molecule, and an organopolysiloxane containing two or more hydrogen atoms bonded to a silicon atom in one molecule. In a semiconductive silicone elastomer composition containing a hydrogen polysiloxane and a conductive substance, the conductive substance is 1 to 10% by weight of conductive carbon and has a volume resistivity of 10 ¹ to 10 ⁸ Ω · c.
together comprising a conductive filler 90 to 99% by weight of non-conductive carbon m, made by the conductive material is blended 20-60% by weight of the total composition, ^{10 5} ~10 10 Ω · c
A semiconductive silicone elastomer composition which provides a semiconductive silicone elastomer having a volume resistivity distribution of 1 to 10 in the range of m. 2. The composition further comprises a non-conductive inorganic filler, and the content of the conductive filler is 50 to 80% by weight of the total amount of the conductive substance and the inorganic filler. 2. The semiconductive silicone elastomer composition according to 1. 3. The conductive filler other than conductive carbon is at least one selected from conductive zinc white, titanium black, black iron oxide, tin oxide, antimony oxide, germanium, and magnetite. Or the semiconductive silicone elastomer composition according to 2 above. 4. The method according to claim 1, wherein a part or all of the organopolysiloxane containing two or more aliphatic unsaturated hydrocarbon groups bonded to a silicon atom in one molecule and all of the conductive carbon are used.
After kneading under heating at 0 to 200 ° C., the mixture is cooled to room temperature, and then all conductive fillers other than conductive carbon having a volume resistivity of 10 ¹ to 10 ⁸ Ω · cm are added thereto, The mixture is remixed at 0 to 60 ° C. to produce a base compound. Then, the base compound is mixed with the remaining organopolysiloxane and an organohydrogenpolysiloxane containing at least two hydrogen atoms bonded to silicon atoms in one molecule. The method for producing a semiconductive silicone elastomer composition according to claim 1, wherein the composition is added.