JP3158879B2 - Semiconductive silicone rubber members for office machines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to rolls and belts for office machines such as copiers and facsimiles, and more particularly to 1 * 10 < ³ >
Semiconductive silicone rubber members for office machines particularly useful for semiconductive silicone rubber rolls and semiconductive silicone rubber belts such as charging rolls, transfer rolls, and developing rolls set to a specific resistance value of 1 × 10 ¹² Ω · cm. About.

[0002]

2. Description of the Related Art Roll materials are one of the rubber materials for office machines. Currently, rubber materials include silicone rubber, urethane elastomer, ethylene propylene rubber, natural rubber and the like. And various composite materials have been proposed. These rubber materials have been used for various purposes as an electrically insulating material or as a conductive material containing a conductive material for the purpose of preventing static electricity or conducting electricity. 10 ³ to 1 × 10 ¹² Ω
Cm The semi-conductive material in the medium resistance region has been used for roll materials such as copying machines.

[0003] The semiconductive roll material has a very stable resistance value in most usage environments in order to control the current flowing according to the resistance value of the rubber material itself, for example, to have a purpose such as transfer ability. It is important. Further, in order to stabilize the value of the current flowing through the roll material, and to effectively apply a charge to the OPC, a voltage of 300 V
A voltage of 10 KV is often applied.

However, in such a use environment under a high voltage, most of the semiconductive roll materials do not have sufficient withstand voltage characteristics, and the resistance value is deviated from the set resistance value when used for a long time. There is a problem. Particularly, the higher the voltage becomes, and the more the current flows, the more remarkably this drawback appears.

The present invention has been made to improve the above circumstances, and uses a silicone rubber mixed with a high proportion of conductive zinc white for a roll material, thereby enabling a roll to be used under a high voltage or the like. The purpose of the present invention is to provide a semiconductive silicone rubber member for office machines, such as a semiconductive silicone rubber roll and a semiconductive silicone rubber belt, which can stabilize the resistance value of a belt or belt and can withstand long-term use under high voltage. .

[0006]

The present inventors have made intensive studies to achieve the above object, and as a result, rolled a silicone rubber containing a high proportion of conductive zinc oxide into the silicone rubber. Used as a material for office equipment such as belts, and has a large amount of conductive zinc on the surface of rolls and belts, so it is stable against changes in resistance under high voltage and can withstand long-term use It has been found that a semiconductive silicone rubber roll and a semiconductive silicone rubber belt can be obtained.

That is, a silicone rubber containing an organopolysiloxane represented by the above average composition formula (1), a reinforcing silica powder having a specific surface area of 50 m ² / g or more, conductive zinc white, and, if necessary, conductive carbon black. The composition can be cured by an organic peroxide or an organohydrogenpolysiloxane / platinum catalyst, or by a combination system of an organic peroxide catalyst and an organohydrogenpolysiloxane / platinum catalyst. Because of the presence of a large amount of conductive zinc white on the surface of rolls and belts, there is little change in the resistance of semiconductive members for office machines used under high voltage, and it can withstand long-term use. The inventors have found that they are most suitable for rolls and belts for machines, and have accomplished the present invention.

Accordingly, the present invention provides a semiconductive silicone rubber composition having a specific resistance of 1 × 10 ³ to 1 × when cured.
In a semiconducting silicone rubber member for office machines of 10 ¹² Ω · cm, the composition is (A) an organopolysiloxane 100 having the following average composition formula (1) and having at least two aliphatic unsaturated groups.
Parts by weight, R ¹ _n SiO _{(4-n) / 2} (1) (where R ¹ is the same or different unsubstituted or substituted 1
And n is a positive number from 1.98 to 2.02. (B) 5 to 70 parts by weight of a reinforcing silica powder having a specific surface area of 50 m ² / g or more, (C) 30 to 700 parts by weight of conductive zinc white, (D) 0 to 50 parts by weight of conductive carbon black, (E) A semiconductive silicone rubber member for office machines, comprising a curing agent in an amount capable of curing the component (A).

Hereinafter, the present invention will be described in more detail. The organopolysiloxane as the first essential component of the silicone rubber composition according to the present invention is represented by the following average composition formula (1).

R ¹ _n SiO _{(4-n) / 2} (1) wherein R ¹ is the same or different unsubstituted or substituted 1
And n is a positive number from 1.98 to 2.02. )

In the above formula, R ¹ is an alkyl group such as a methyl group, an ethyl group, a propyl group or a butyl group, a cycloalkyl group such as a cyclohexyl group, a vinyl group, an allyl group,
Alkenyl groups such as butenyl group and hexenyl group, aryl groups such as phenyl group and tolyl group, or chloromethyl in which part or all of the hydrogen atoms bonded to carbon atoms of these groups are substituted with halogen atoms, cyano groups, etc. And the same or different unsubstituted or substituted monovalent hydrocarbon groups having 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, selected from a group, trifluoropropyl group, cyanoethyl group and the like. In this case, R ¹ needs to have at least two aliphatic unsaturated groups (alkenyl groups),
The content of the aliphatic unsaturated group in R ¹ is desirably 0.001 to 20 mol%, particularly preferably 0.025 to 5 mol%. N is a positive number between 1.98 and 2.02. The organopolysiloxane of the above formula (1) is preferably basically linear, but one or two having a different molecular structure.
It may be a mixture of more than one species.

Further, the above-mentioned organopolysiloxane has an average degree of polymerization of 100 to 10,000, especially 3,000 to 8,
000 is preferred.

Next, the reinforcing silica powder, which is the second essential component of the silicone rubber composition, is essential for obtaining a silicone rubber having excellent mechanical strength. Has a specific surface area of 50 m ² / g or more,
Preferably, it is required to be 100 to 300 m ² / g.
If the specific surface area is less than 50 m ² / g, the mechanical strength of the cured product will be low.

Examples of such reinforcing silica powder include fumed silica, precipitated silica, and the like, and those whose surfaces are hydrophobized with chlorosilane, hexamethyldisilazane, or the like are also preferably used.

The amount of the reinforcing silica powder to be added is 5 to 70 parts based on 100 parts of the first component organopolysiloxane.
In particular, it is preferably 10 to 50 parts, and if it is less than 5 parts, the amount of addition may be too small to obtain a reinforcing effect,
If the amount exceeds 70 parts, workability may deteriorate and mechanical strength may decrease.

[0016]

The conductive zinc white, which is the third essential component of the present invention, is obtained by calcining an insulating zinc white at a high temperature in a vacuum to increase the conductivity and further dissolving aluminum oxide in the zinc white. Products made of conductive zinc white, specifically, conductive zinc white
1, conductive zinc white 2. Conductive zinc white FX (all manufactured by Honjo Chemical Co., Ltd.) and the like, and the above-mentioned conductive zinc white doped with aluminum is particularly preferable.

The addition amount is from 30 to 700 parts, preferably 1 part, per 100 parts of the first component organopolysiloxane.
The amount is preferably from 00 to 400 parts, and the maximum amount is preferably added so as not to affect the required physical properties of the rubber member. If the addition amount is less than 30 parts, sufficient conductive zinc white does not appear on the surface of the rubber member, and the intended effect may not be recognized. If the addition amount exceeds 700 parts, the compounding becomes extremely difficult, and the physical (mechanical) Target) The characteristics may decrease.
If the amount of the conductive zinc white exceeds 400 parts, the compoundability deteriorates and the compound may not be formed. However, if the compounding is difficult, the low polymerization degree (average polymerization) of the first component organopolysiloxane is difficult. (1,000 degrees or less) may be added in an appropriate amount.

The silicone rubber composition according to the fourth aspect of the present invention
The conductive carbon black, which is a component, is an optional component suitable for adjusting to a target volume resistance value, and is not particularly limited, and may be a component usually blended in a silicone rubber composition. it can. Specifically, acetylene black, conductive furnace black (CF), superconductive furnace black (SCF), extra conductive furnace black (XCF), conductive channel black (CC), and furnace black and channels heat-treated at a high temperature of about 1500 ° C. Black and the like can be mentioned.

Specific examples of acetylene black include electrified acetylene black (manufactured by Denki Kagaku), Shaunigan acetylene black (manufactured by Shaunigan Chemical Company), and conductive furnace black include Continex CF (manufactured by Continental Carbon Co., Ltd.). ), Vulcan C (manufactured by Cabot Corporation), and Continex SCF as specific examples of superconductive furnace black.
Specific examples of (Continental Carbon), Vulcan SC (Cabot), and Extra Conductive Furnace Black include Asahi HS-500 (Asahi Carbon), Vulcan XC-72 (Cabot), and Conductive Channel Black. , Kolux L
(Made by Degussa). Ketjen Black EC and Ketjen Black EC-600JD (Ketjen Black International), which are one type of furnace black, can also be used.

Among these, acetylene black has a low impurity content and has a developed secondary structure structure and thus has excellent conductivity, and is particularly preferably used in the present invention. In addition, Ketjen Black EC and Ketjen Black EC-600JD exhibit excellent conductivity even at a low filling amount due to their excellent specific surface area.
Etc. can also be preferably used.

The conductive carbon black is added in an amount of 0 to 100 parts by weight of the first component organopolysiloxane.
It is preferably 50 parts, especially 1 to 10 parts. If it exceeds 50 parts, the resulting member may have an electrical resistance of 10 ² Ω or less, and may not be the intended semiconductive region.

[0023]

In the present invention, a known organohydrogenpolysiloxane / platinum catalyst (curing agent for addition reaction) or an organic peroxide catalyst can be used as the curing agent of the fifth essential component.

As the platinum-based catalyst, known catalysts can be used, and specifically, a platinum element simple substance, a platinum compound, a platinum complex, chloroplatinic acid, an alcohol compound of chloroplatinic acid, an aldehyde compound, an ether compound, various olefins And the like. The amount of the platinum-based catalyst to be added is preferably in the range of 1 to 2,000 ppm as platinum atoms based on the organopolysiloxane of the first component.

On the other hand, the organohydrogenpolysiloxane may be linear, branched or cyclic, but preferably has a degree of polymerization of 300 or less, and the terminal is blocked with a dimethylhydrogensilyl group. Diorganopolysiloxanes, copolymers of dimethylsiloxane units with methylhydrogensiloxane units and terminal trimethylsiloxy units, low-molecular-weight copolymers composed of dimethylhydrogensiloxane units ( _0.5 units of H (CH ₃ ) ₂ SiO) and SiO ₂ units Viscous fluid, 1,3,5,7-tetrahydrogen-1,3,5,7-tetramethylcyclotetrasiloxane, 1-propyl-3,5,7-trihydrogen-1,3,5,7 -Tetramethylcyclotetrasiloxane, 1,5-dihydrogen-3,7-dihexyl-1,3,5, - tetramethyl cyclotetrasiloxane and the like.

The addition amount of the organohydrogenpolysiloxane as the curing agent is such that the hydrogen atom directly bonded to the silicon atom is 50 to 500 with respect to the aliphatic unsaturated group (alkenyl group) of the organopolysiloxane of the first component. Mol%
It is desirable to use them in such a ratio.

Examples of the organic peroxide catalyst include, for example, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, p-methylbenzoyl peroxide, 2,4-dicumyl peroxide, and 2,5-dimethyl-bis. (2,5-t-butylperoxy) hexane,
Di-t-butyl peroxide, t-butyl perbenzoate and the like. The addition amount of the organic peroxide catalyst may be 0.1 to 5 parts with respect to 100 parts of the first component organopolysiloxane.

The silicone rubber composition according to the present invention comprises:
In addition to the above-mentioned essential components, if necessary as long as the effects of the present invention are not impaired as optional components, other inorganic materials such as titanium oxide, silicone rubber powder as a bulking agent, redwood,
Ground quartz, calcium carbonate, etc. may be added. Further, an inorganic or organic foaming agent for forming a sponge may be added. Examples of the foaming agent include azobisisobutyronitrile, dinitropentamethylenetetramine, benzenesulfone hydrazide azodicarbonamide, and the like.
The range of 1 to 10 parts per part is preferable.

By adding a foaming agent to the composition of the present invention, a sponge-like silicone rubber can be obtained.

It is optional to add various additives such as a colorant and a heat resistance improver, a reaction control agent, a release agent or a filler dispersant to the composition of the present invention, if necessary. However, diphenylsilanediol, various alkoxysilanes, carbon functional silane, silanol group-containing low molecular weight siloxane, etc. used as the filler dispersant are limited to the minimum amount so as not to impair the effects of the present invention. Is preferred.

Further, in order to make the silicone rubber composition of the present invention flame-retardant and fire-resistant, platinum-containing materials, platinum compounds and titanium dioxide, platinum and manganese carbonate, platinum and γ-Fe
Known additives such as ₂ O ₃ , ferrite, mica, glass fiber and glass flake may be added.

In the silicone rubber composition according to the present invention, the above-mentioned components are uniformly mixed by using a rubber kneading machine such as a two-roll mill, a Banbury mixer or a dough mixer (kneader). In this case, for example, the base compound is prepared by previously mixing the organopolysiloxane of the first component and the reinforcing silica powder of the second component, and the conductive compound of the third component is added thereto. Zinc white, the conductive carbon black of the fourth component, may be prepared by mixing in advance a three-roll treatment with the organopolysiloxane of the first component, and then mixing and dispersing the three components. May be added and mixed.

In this case, the conductive zinc white is preferably subjected to a three-roll treatment in order to disperse it uniformly. If the dispersibility is not good, the resistance value of a certain portion may be different from the surrounding resistance value, which may lead to white spots on the image of the copying machine or uneven printing.

The silicone rubber composition thus obtained is coated and laminated on a core metal of a roll or a belt substrate, and then cured. The curing is carried out by a usual vulcanization method of silicone rubber such as press vulcanization, normal pressure hot air vulcanization (HAV), and steam vulcanization (CV).
It can be performed at 0 ° C. for about 30 seconds to 5 hours.

In this case, it is preferable to use a primer or an adhesive in order to adhere the silicone rubber to the core metal or the belt base material.

The thickness of the silicone rubber layer coated on the roll core, the belt base material and the like is appropriately selected, but is usually from 0.2 to 20 mm, especially from 1 to 6 mm.

The semiconductive silicone rubber member for office machines of the present invention uses a silicone rubber mixed with a high proportion of conductive zinc white, so that the rubber material used under a high voltage or the like is unique to the material. Stabilized against changes in resistance,
Semiconductive silicone rubber members such as rolls and belts for office machines that can withstand long-term use under high voltage, especially 1 ×
It is used as a charging roll, a transfer roll, a developing roll or the like set to a specific resistance value of 10 ³ to 1 × 10 ¹² Ω · cm.

[0039]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, Reference Examples, and Comparative Examples, but the present invention is not limited to the following Examples.

REFERENCE EXAMPLE 1 A rubber comprising 99.825 mol% of dimethylsiloxane units, 0.15 mol% of methylvinylsiloxane units and 0.025 mol% of dimethylvinylsiloxane units and having an average degree of polymerization of about 5,000. Organopolysiloxane 10
0 parts, 3 parts of diphenylsilanediol as a dispersant,
Terminal silanol group dimethylpolysiloxane (degree of polymerization n =
10) 4 parts and 30 parts of treated silica (manufactured by Nippon Aerosil Co., Ltd.) having a specific surface area of 200 m ² / g were added by a kneader, kneaded, and heat-treated at 160 ° C. for 2 hours to prepare a base compound.

After 100 parts of the above base compound and 50 parts of Zinhua No. 3 (manufactured by Honjo Chemical Co., Ltd.) and 6 parts of Denka acetylene black (manufactured by Denki Kagaku Kogyo KK) were kneaded with a pressure kneader, and the three pieces were kneaded. The compound was prepared by uniformly dispersing the compound with a roll.

In the above compound, 2,5-
2 parts of dimethyl-2,5-di (t-butylperoxy) hexane is kneaded, and 20 m in diameter is placed on a core having a diameter of 10 mm.
m rolls (5 mm thick) were produced. Molding temperature is 16
The molding pressure was 5 ° C./10 minutes, and the molding pressure was 30 kgf / cm ² .

[Examples 1 and 2, Reference Examples 2 to 4, Comparative Examples 1 and 2] Rolls were produced in the same manner as in Reference Example 1 at the compounding ratios shown in Table 1. However, the base compounds are all the same,
Carbon black is Denka acetylene black, zinc white is zinc white 3, organic peroxide is 2,5-dimethyl-2,
For 5-di (t-butylperoxy) hexane and conductive zinc white, conductive zinc white FX (manufactured by Honjo Chemical Co., Ltd.) was used.

In the vulcanization method, methylhydrogensiloxane / platinum was used in an amount of 0.5 g of an alcohol solution of chloroplatinic acid (platinum amount: 1.0%) with respect to 100 parts of the compound.
1.2 parts of methyl hydrogen polysiloxane having a SiH content of 0.005 mol% was used.

The obtained silicone rubber roll was heated at 200 ° C.
After the post-curing for / 4 hours, the roll 1 was placed on a platinum electrode plate A placed on a glass epoxy substrate B as shown in FIG. 1 core metal 2
After applying a current of 4 KV / 10 min between the platinum electrode plates A, the resistance value of the silicone rubber was measured, and the rate of the change was calculated.
In addition, the resistance value of the roll 1 measured the electric property between the electrode 3 and the core metal 2 by making the roll 1 contact the electrode 3 as shown in FIG. The measuring voltage was 100 V, and the measuring device 4 was Advantest Digital Super Resistance Meter R8340. Table 1 shows the results.

[0046]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a perspective view showing an apparatus for applying a high voltage to a semiconductive silicone rubber roll.

FIG. 2 is a plan view of an apparatus for measuring the resistance of the silicone rubber roll.

[Description of Signs] 1 Roll 2 Core 3 Electrode 4 Measuring instrument

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI H01B 1/00 H01B 1/00 A 1/24 1/24 Z (72) Inventor Masaharu Takahashi Matsuida-machi, Daiji, Hitomi, Gunma Prefecture 1-10 Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory (72) Inventor Tomiyoshi Tsuchida 1-chome, Matsuida-cho, Usui-gun, Gunma Prefecture 1-10 Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory (56) Reference Document JP-A-6-41434 (JP, A) JP-A-6-41437 (JP, A) JP-A-59-45356 (JP, A) JP-A-55-120657 (JP, A) 295263 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 83/07 C08K 3/04 C08K 3/22 C08K 3/36

Claims (3)

(57) [Claims] 1. A semiconductive silicone rubber member for office machines having a specific resistance value of 1 × 10 ³ to 1 × 10 ¹² Ω · cm obtained by curing a semiconductive silicone rubber composition, wherein the composition comprises ( A) An organopolysiloxane 100 represented by the following average composition formula (1) and having at least two aliphatic unsaturated groups:
Parts by weight, R ¹ _n SiO _{(4-n) / 2} (1) (where R ¹ is the same or different unsubstituted or substituted 1
And n is a positive number from 1.98 to 2.02. (B) 5 to 70 parts by weight of a reinforcing silica powder having a specific surface area of 50 m ² / g or more, (C) 30 to 700 parts by weight of conductive zinc white, (D) 0 to 50 parts by weight of conductive carbon black, (E) A semiconductive silicone rubber member for office machines, comprising a curing agent in an amount capable of curing the component (A). 2. The semiconductive silicone rubber member for office machines according to claim 1, wherein the conductive zinc white is doped with aluminum. 3. The semiconductive silicone rubber member for an office machine according to claim 1, wherein the semiconductive silicone rubber member is a semiconductive silicone rubber roll or a semiconductive silicone rubber belt.