JPH08157724A - Production of semiconductive roll - Google Patents

Abstract

PURPOSE: To industrially advantageously produce a semiconductive roll having low dispersion of surface resistivity and volume resistivity and therefore stable in quality. CONSTITUTION: This production process comprises compression-molding a silicone rubber composition comprising 100 pts.wt. organopolysiloxane represented by the average compositional formula: RSiO(4-n)/2 (wherein Rs, which may be the same or different from each other, are (un)substituted monovalent hydrocarbons; and (n) is a positive number of 1.98-2.02), 3-300 pts.wt. conductive material, 5-200 pts.wt. spherical silicone elastomer particles having a particle diameter of 0.1-100μm and 0.1-5 pts.wt. curing agent against the surface of a core metal at such a pressure that the internal pressure exerted on the composition is 70kgf/cm<2> or below, and vulcanizing the molding to form a semiconductive roll-like silicone rubber layer around the core metal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a semiconductive roll capable of industrially producing a semiconductive roll excellent in stability of electric resistance in a semiconductive region.

[0002]

2. Description of the Related Art Silicone rubber is used as a roll material for copying machines, printers, facsimiles and the like because it is excellent in environmental stability and compression set resistance. Further, recently, as a measure against ozone, a charging roll, a developing roll, a transfer roll, a cleaning roll, and a carrying roll used in a contact type developing device have a resistance between the core metal and the roll surface of 10 ^4.
The use of silicone rubber moldings in the conductive region of about -10 ¹⁰ ohms is also being considered.

However, the resistance of the semiconductive roll around the development needs to be in an extremely narrow range,
It was difficult to manufacture. Further, generally, in order to obtain a silicone rubber layer having a resistance of 10 ⁴ to 10 ¹⁰ ohms between the core metal and the surface of the roll, conductive carbon black is added to the silicone rubber composition. There is a problem that it is difficult to stabilize in the semiconductive region.

Further, Japanese Patent Laid-Open No. 5-28691 discloses that
Molding pressure of conductive silicone rubber composition consisting of organopolysiloxane, conductive material and curing agent 30 kgf / c
Although it is described that the molding is performed with m ² , there is a problem that the resistance varies depending on the internal pressure of the silicone rubber composition in the mold even if the molding pressure is the same.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method of manufacturing a semiconductive roll having a stable quality and a small variation in electric resistance in the semiconductive region. To do.

[0006]

Means and Actions for Solving the Problems
As a result of intensive studies to achieve the object, (A) 100 parts by weight of an organopolysiloxane represented by the following average composition formula (1) R SiO_{(4-n) / 2} (1) (wherein R is the same or different, unsubstituted or substituted monovalent hydrocarbon group, and n is a positive number of 1.98 to 2.02.) (B) Conductive material 3 to 300 parts by weight (C) Spherical silicone elastomer particles having an average particle size of 0.1 to 100 μm 5 to 200 parts by weight (D) Curing agent 0.1 to 5 parts by weight Silicone rubber composition core Composition on gold surface
Internal pressure on the object 70kgf / cm²Compression molding with
・ Vulcanizes to form a semi-conductive roll-like silicone rubber layer
As a result, the gap between the cored bar and the roll surface is 10^Four-10
^TenIt has a resistance on the order of ohms, and the electric current in this semiconducting region is
Form a semi-conductive silicone rubber layer with a small variation in air resistance
Semi-conductive roll that can be made and has stable quality
Was found to be industrially advantageous.

That is, the compression molding is the most general molding technique as a rubber molding method, and the low pressure compression molding technique is particularly effective for molding a semiconductive roll. Conventionally, roll molded products were molded using a compression molding machine or an injection molding machine without fully clarifying the effect of molding pressure on the characteristics, but in this case, the pressure associated with molding occurs, and this pressure is changing the dispersion of the conductive material such as conductive carbon black, therefore, the conductive region (10 ⁴ to 10
It was impossible to obtain a stable resistance value of ¹⁰ ohms. On the other hand, when the silicone rubber composition is compression molded at an internal pressure of 70 kgf / cm ² or less applied to the composition, the internal pressure generated inside the material is relaxed before the curing. Therefore, the inventors have found that the dispersed state of the electrically conductive material is uniform over the entire roll, the variation is small, and a stable surface resistance value and volume resistance value can be obtained, and the present invention has been completed.

Therefore, according to the present invention, (A) 100 parts by weight of the organopolysiloxane represented by the above average composition formula (1) (B) 3 to 300 parts by weight of the conductive material (C) The average particle diameter is 0.1 to 0.1 parts by weight. A silicone rubber composition containing 100 μm spherical silicone elastomer particles 5 to 200 parts by weight (D) curing agent 0.1 to 5 parts by weight is compressed on the surface of a core metal at an internal pressure of 70 kgf / cm ² or less applied to the composition. Provided is a method for producing a semiconductive roll, which comprises molding and vulcanizing to form a semiconductive roll-shaped silicone rubber layer.

The present invention will be described in more detail below.
And in the method for producing a semiconductive roll of the present invention,
Silicone rubber forming an electrically conductive roll-shaped silicone rubber layer
The organopolysiloxane of component (A) of the
Average composition formula R SiO_{(4-n) / 2} (1) (wherein R is the same or different and is unsubstituted or substituted monovalent
It is a hydrocarbon group, and n is a positive number of 1.98 to 2.02.
It ).

In the above formula (1), R is preferably an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, such as methyl group, ethyl group, Alkyl groups such as propyl group, alkenyl groups such as vinyl group, cycloalkyl groups such as cyclohexyl group, aryl groups such as phenyl group and tolyl group, some or all hydrogen atoms of these groups are halogen atoms, cyano groups, etc. And a group selected from a chloromethyl group substituted with, a trifluoropropyl group, a cyanoethyl group, and the like. Further, it is preferable that 0.001 to 5 mol%, particularly 0.01 to 0.5 mol% of R is an alkenyl group. n is 1.98
Is a positive number of 2.02.

The organopolysiloxane of the above formula (1) is basically linear, but may be branched or cyclic, and may be one kind or a mixture of two or more kinds having different molecular structures. The viscosity at 25 ℃ is 100 cs
Above all, the range of 100,000 to 10,000,000 cs is particularly preferable. The degree of polymerization is 100 or more, especially 3
The range of 000 to 10,000 is preferable.

The above-mentioned organopolysiloxane is (co) containing one or more kinds of usually selected organohalosilanes.
It can be obtained by hydrolysis or by ring-opening polymerization of a cyclic polysiloxane (such as a trimer or tetramer of siloxane) using an alkaline or acidic catalyst.

The conductive material as the component (B) is not particularly limited as long as it is a substance capable of imparting conductivity, and for example, various metal powders such as carbon black, graphite, silver, nickel and copper, and various non-metals. Conductive powder, short fiber surface treated with metal such as silver, carbon fiber, metal fiber, conductive zinc oxide, conductive titanium oxide, titanium oxide surface treated with tin and antimony (eg Mitsubishi Materials WP-10, ECM-S2) and the like can be mentioned.

In this case, electroconductive carbon black is suitable as the electroconductive material, and as the electroconductive carbon black, those usually blended with silicone rubber can be used. Specific examples thereof include acetylene black, conductive furnace black, conductive channel black and the like. Further, as the acetylene black, specifically, electrified acetylene black (manufactured by Denki Kagaku) and Ketchan Black EC (manufactured by Ketchan Black International), which is a type of furnace black, can be used. In the present invention, two or more kinds of the above-mentioned conductive materials may be mixed and added.

The amount of the conductive material added varies depending on the material used, but is usually 3 to 300 relative to 100 parts (parts by weight, hereinafter the same) of 100 parts (A) of the organopolysiloxane.
Parts, in the case of conductive carbon, 3 to 30 parts, particularly 5 to 20 parts per 100 parts of the organopolysiloxane of component (A).
Parts, conductive zinc white and conductive titanium oxide are 10
300 parts, especially 50 to 250 parts, and in the case of ECM-S2, 5 to 40 parts, especially 10 to 30 parts are preferable. If the added amount of the conductive material is less than the above amount, satisfactory conductivity cannot be obtained, and if the added amount exceeds the above amount, it may become too conductive and the semiconductive region may not be formed.

The spherical silicone elastomer particles as the component (C) are blended to stabilize electric resistance.
The average particle size is 0.1 to 100 μm, preferably 0.1.
The one having a thickness of 5 to 40 μm is used. The average particle size is 0.
Particles having a particle size of less than 1 μm are difficult to produce, and it is difficult to sufficiently obtain the effect of addition thereof.

The spherical silicone elastomer particles are not limited in kind, grade, manufacturing method and the like as long as they are a cured product of an organopolysiloxane having the above-mentioned average particle diameter and have a spherical shape. Although the spherical silicone elastomer particles are not particularly limited, a method of obtaining a granular silicone elastomer by curing a curable organopolysiloxane composition in a spray dryer at 120 to 300 ° C. 59-96122), a curable organopolysiloxane composition, for example, an addition reaction type organopolysiloxane composition composed of a vinyl group-containing organopolysiloxane and an organohydrogenpolysiloxane in water using a surfactant. A method of emulsifying emulsion particles to a particle size of 20 μm or less, adding a platinum catalyst for addition reaction, and curing the organopolysiloxane contained in the emulsion particles before or after spray drying ( Japanese Patent Laid-Open No. 62-25793 It is possible to use those obtained by a method such as the method described in JP-A No. 1993-2000). Particularly, vinyl group-containing organopolysiloxane and organohydrogenpolysiloxane are made into an emulsion by using a surfactant, and the emulsion is subjected to an addition reaction with a platinum catalyst and cured. Those manufactured by the above method are preferable. As the elastomer particles, those whose surface is treated with silane, siloxane or the like in advance or during the production thereof can be used.

The spherical silicone elastomer particles are used in an amount of 5 to 200 parts, preferably 10 to 150 parts, based on 100 parts of the organopolysiloxane of the above formula (1). If the effect is not obtained and the electrical resistance becomes unstable, and the amount exceeds 200 parts, the mechanical strength of the cured product decreases.

As the curing agent as the component (D), a conventionally known one depending on the crosslinking reaction mechanism of the silicone composition can be used. Specifically, an organic peroxide which is a kind of cross-linking agent, for example, benzoyl peroxide, 2,4-
Dichlorobenzoyl peroxide, 2,5-dimethyl-bis (2,5-t-butylperoxy) hexane, p
-Methylbenzoyl peroxide, dicumyl peroxide, 1,6-bis (t-butylperoxycarboxy) hexane and the like are preferably used.

The amount of the curing agent added is 0.1 to 5 parts, preferably 0.2 to 3 parts, per 100 parts of the component (A) organopolysiloxane.

When the organopolysiloxane as the component (A) has two or more alkenyl groups directly bonded to silicon atoms, two or more S in one molecule as a curing agent.
The silicone rubber composition can be cured by using an iH group-containing organohydrogenpolysiloxane and crosslinking them by an addition reaction (hydrosilylation reaction) thereof.

In this case, the organohydrogenpolysiloxane may be linear, branched or cyclic, but preferably has a degree of polymerization of 300 or less. Specifically, a diorganopolysiloxane whose end is blocked with a dimethylhydrogensilyl group, a copolymer of a dimethylsiloxane unit and a methylhydrogensiloxane unit, a dimethylhydrogensiloxane unit (H (CH
₃ ) a low-viscosity fluid composed of ₂ SiO _0.5 units) and SiO ₂ units, 1,3,5,7-tetrahydrogen-1,3,3
5,7-Tetramethylcyclotetrasiloxane, 1-propyl-3,5,7-trihydrogen-1,3
5,7-Tetramethylcyclotetrasiloxane, 1,5
-Hydrogen-3,7-dihexyl-1,3,5
Examples thereof include 7-tetramethylcyclotetrasiloxane.

The organohydrogenpolysiloxane as the curing agent has a hydrogen atom of SiH group of 50 relative to the alkenyl group of the organopolysiloxane of the component (A).
It is preferably used in a proportion of about 500 mol%.

A known platinum-based catalyst is preferably added to the addition reaction of the organopolysiloxane with the organohydrogenpolysiloxane, specifically, platinum simple substance, platinum compound, platinum complex, chloroplatinic acid chloride. , Complexes with various olefins, and the like. The amount of the platinum-based catalyst added is preferably in the range of 1 to 2000 ppm as platinum atom with respect to the organopolysiloxane of the component (A).

The silicone rubber composition according to the present invention may contain other components in addition to the above essential components. For example, a well-known silica-based filler may be added. As the reinforcing silica used as the silica-based filler, general ones that have been conventionally compounded in silicone rubber and the like can be used.
The specific surface area measured by the method is 50 m ² / g or more, and in order to obtain a further excellent reinforcing effect, the specific surface area is 100 m ² / g.
It is preferable to use the above.

The reinforcing silica is roughly classified into a dry method and a wet method depending on its manufacturing method. As silica obtained by the dry method (dry silica), Aerosil (manufactured by Nippon Aerosil Co., Ltd.), Cabosil (manufactured by Cabot Corp.), or the like can be used. Examples of silica obtained by the wet method (wet silica) include Carplex (manufactured by Shionogi), Tokusil (manufactured by Tokuyama Soda Co., Ltd.), and Nipseal (manufactured by Nihon Silica).

The amount of reinforcing silica added is preferably in the range of 10 to 200 parts, particularly 20 to 80 parts, relative to 100 parts of component (A), and if less than 10 parts, a sufficient reinforcing effect cannot be obtained. If it exceeds 200 parts, satisfactory strength and durability may not be obtained.

Further, in order to improve weather resistance and flame retardancy, or to form a sponge, the following additives and foaming agents may be used in combination. For example, titanium oxide, aluminum oxide, metal oxides such as iron oxide as additives, calcium oxide, mica powder, clay, talc, quartz powder, celite, aluminum hydroxide, flame retardant, colorant,
Mold release agents, ultraviolet absorbers, dispersants, process oils, higher fatty acids such as stearic acid and lauric acid, various carbon functional silanes, and the like, and as the foaming agent, inorganic foaming agents such as sodium bicarbonate, Examples include nitroso compounds, azo compounds, sulfonyl hydrazides and the like.

The composition of the present invention comprises (A) to (C)
Banbury mixer, whose ingredients are commonly used for rubber,
Kneading is performed using a kneader, intermixer, two-roll mixer or the like. At this time, if necessary, after heat treatment or aging, the prepared silicone rubber compound is cured as the component (D). A semiconductive roll can be obtained by adding the agent using a kneader such as a roll or a Banbury mixer, and then compression-molding and vulcanizing this on the surface of the cored bar.

In this case, aluminum, steel or the like is preferably used as the core metal forming the semiconductive silicone rubber roll.

The silicone rubber composition is preferably formed in a layer having a desired thickness (usually 0.5 to 30 mm) on the surface of the cored bar.

The internal pressure applied to the silicone rubber composition during compression molding is 70 kgf / cm ² or less, preferably 50 kgf / cm ² or less.
If it exceeds cm ² , the dispersion of carbon changes due to the internal pressure. The internal pressure can be controlled by the pressure at the time of injection, the pressure at the time of charging the mold, etc., but the control at the time of injection is most preferable. Also,
The molding pressure is not particularly limited, but is preferably low, and there is no lower limit to the conditions unless the molded product has fine foaming. For example, after molding at an initial pressure of 50 kgf / cm ² , 10 kgf /
It may be molded at a low pressure of about cm ² .

The semiconductive roll thus obtained has a resistance of about 10 ⁴ to 10 ¹⁰ ohms between the core metal and the surface of the roll, and the electric resistance is stable in the semiconductive region. A silicone rubber layer is formed on a cored bar.

[0034]

According to the method for producing a semiconductive roll of the present invention, there is little variation in surface resistance and volume resistance, and a semiconductive roll having a resistance of about 10 ⁴ to 10 ¹⁰ ohms is provided between the core metal and the surface of the roll. A conductive silicone rubber layer is formed, and a semiconductive roll having stable quality can be industrially advantageously manufactured.

[0035]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. All parts in each example are parts by weight.

[Examples 1 to 3, Comparative Examples 1 to 4] Dimethyl siloxane unit is 99.825 mol%, methyl vinyl siloxane unit is 0.15 mol% and dimethyl vinyl siloxane unit is 0.025 mol%. Is about 80
100 parts of methyl vinyl polysiloxane of 00, 3 parts of diphenylsilanediol as a dispersant, 4 parts of terminal silanol group dimethyl polysiloxane (polymerization degree of 10) and silica having a specific surface area of 200 m ² / g (manufactured by Nippon Aerosil Co., Ltd.). 30 parts were added and heat-treated at 150 ° C. for 2 hours with a kneader to prepare a base compound A.

100 parts of the above-mentioned base compound A, electrified acetylene black (manufactured by Denki Kagaku) and conductive zinc flower F
X (manufactured by Honjo Chemical Co., Ltd.), spherical silicone elastomer particles (average particle size 13 μm, X-52-874, manufactured by Shin-Etsu Chemical Co., Ltd.), and dicumyl peroxide as a curing agent were mixed in the ratios shown in Tables 1 and 2.

Next, on a metal (SUS) shaft having a diameter of 6 mm, the molding pressure was adjusted by the hydraulic pressure of the ram using an injection molding machine, and the internal pressure was adjusted by adjusting the flange pressure. Compression molded with a diameter of 20
A roll of mm was obtained. This roll at 200 ℃ for 30 minutes 1
Secondary vulcanization, electrical resistance after secondary vulcanization at 200 ° C for 4 hours
It measured using the apparatus shown in. The roll 1 is 7m
Then, the electrical resistance between the electrode 2 and the cored bar 3 was measured by the measuring machine 4. The measuring voltage was 100 V, and the measuring instrument was Advantest Digital Super Resistance Meter R8340.

[0039]

[Table 1]

[0040]

[Table 2]

From the results of Tables 1 and 2, it was confirmed that the semiconductive rolls (Examples) obtained by the manufacturing method of the present invention had stable quality with little variation in electric resistance.

[Brief description of drawings]

FIG. 1 is a schematic view of an electric resistance measuring device used in Examples.

[Explanation of symbols]

 1 roll 2 electrode 3 core metal 4 measuring instrument

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area C08K 5/14 LRT // G03G 15/02 101

Claims (1)

[Claims] 1. (A) 100 parts by weight of organopolysiloxane represented by the following average composition formula (1) R SiO_{(4-n) / 2} (1) (wherein R is the same or different, unsubstituted or substituted monovalent hydrocarbon group, and n is a positive number of 1.98 to 2.02.) (B) Conductive material 3 to 300 parts by weight (C) Spherical silicone elastomer particles having an average particle size of 0.1 to 100 μm 5 to 200 parts by weight (D) Curing agent 0.1 to 5 parts by weight Silicone rubber composition core Composition on gold surface
Internal pressure on the object 70kgf / cm²Compression molding with
・ Vulcanizes to form a semi-conductive roll-like silicone rubber layer
A method for manufacturing a semiconductive roll, comprising: