JPH08157721A - 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 extruding 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 and 0.1-5 pts.wt. curing agent, and molding and vulcanizing the extrudate at a pressure of 70kgf/cm<2> or below against the surface of an a core metal to form a semiconductive roll-like silicone rubber layer.

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
Although it is described that a conductive silicone rubber composition composed of an organopolysiloxane, a conductive material and a curing agent is extrusion-molded, there is a problem that the resistance varies depending on the extrusion conditions.

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

[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) a curing agent 0.1 to 5 parts by weight of a silicone rubber composition is pressed onto the surface of the core metal.
Outlet pressure is 70 kgf / cm²Half-molded and vulcanized below
By forming a conductive roll-shaped silicone rubber layer
Between the core metal and the roll surface^Four-10^TenOhm
Of the electric resistance in this semi-conducting region.
Forming a semi-conductive silicone rubber layer with low flicker
Of semi-conductive rolls that can produce stable and stable quality
It was found that it can be manufactured advantageously.

The extrusion molding technique is a general molding technique used for obtaining a hose molded product and a sponge molded product. However, the relationship between the extrusion pressure and the conductivity, especially in the semi-conductive region where the resistance easily varies. Little was considered about the stability of the resistance. Conventionally, roll molded products were molded using a compression molding machine or an injection molding machine, but in this case, pressure accompanying molding is generated, and this pressure changes the dispersion of conductive materials such as conductive carbon black. ,
Therefore, it was impossible to stably obtain the resistance value of the conductive region (10 ⁴ to 10 ¹⁰ ohm). On the other hand, when the above-mentioned silicone rubber composition is molded at an extrusion pressure of 70 kgf / cm ² or less at the head of an extruder, it is only the head pressure generated during extrusion, and this head pressure is the normal pressure of hot air in the next step. It is relaxed by vulcanization and steam vulcanization, and almost no internal pressure is generated inside the silicone rubber. Therefore, the inventors have found that the dispersed state of the conductive material is uniform over the entire roll and that stable surface resistance value and volume resistance value can be obtained, and the present invention has been completed.

Therefore, the present invention provides (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) 0.1 to 5 parts by weight of the curing agent. A semiconductive roll-shaped silicone rubber layer is formed by extruding and vulcanizing a silicone rubber composition containing a part on the surface of a core metal at a pressure of 70 kgf / cm ² or less. A method for manufacturing the same is provided.

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.

As the curing agent as the component (C), 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, relative to 100 parts of the organopolysiloxane (A).

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 above organopolysiloxane and organohydrogenpolysiloxane. Specifically, simple platinum, platinum compound, platinum complex, chloroplatinic acid chloride is added. , 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, in order to stabilize electric resistance, the particle size is 0.1
It is particularly preferable to add spherical silicone elastomer particles having a particle size of ˜100 μm in a range of 10 to 200 parts with respect to 100 parts of the organopolysiloxane as the component (A).

Further, the composition of the present invention may optionally contain, for example, a well-known silica filler. As the reinforcing silica used as a silica-based filler,
Conventional ones that have been compounded with silicone rubber can be used, but the specific surface area measured by the BET method is 50 m ² / g or more. It is preferable to use a resin having a viscosity of 100 m ² / g or more.

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 the reinforcing silica added is preferably in the range of 10 to 200 parts, particularly 20 to 80 parts, relative to 100 parts of the 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 resistance, 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 preferably has a low plasticity in order to suppress extrusion pressure, and has a Williams plasticity (JIS C-2123) of 100 to 300, particularly 15.
It is preferably 0 to 250. If it is less than 100, the composition may stick to the extruder, and if it exceeds 300, it may be difficult to control the extrusion pressure to 70 kgf / cm ² or less.

The composition of the present invention first comprises (A) and (B)
Banbury mixer, whose ingredients are commonly used for rubber,
The mixture is kneaded using a mixer such as a kneader, an intermixer, or a two-roll mill. At this time, if necessary, heat treatment or aging is performed, and then the prepared silicone rubber compound is cured as the component (C). A semiconductive roll can be obtained by adding the agent using a kneader such as a roll or a Banbury mixer, and then extruding the mixture onto the surface of a core metal and vulcanizing it.

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.

Furthermore, the extrusion pressure during extrusion molding is 7
0 kgf / cm ² or less, preferably one that the 50 kgf / cm ² or less, 70 kgf / cm ² greater than the molding pressure distribution of the carbon is changed by not stable resistance of the semiconductive region are obtained. The extrusion pressure may be obtained by inserting a pressure sensor into the head of the extruder. The molding pressure is not particularly limited, but is preferably low, and there is no lower limit to the condition if the molded product does not have fine foaming, and normal pressure may be used.

The material extruded by the above method is hot air atmospheric vulcanization (200 to 400 ° C. for 5 seconds to 10 minutes) or steam vulcanization (steam pressure 5 kgf / cm ² or more, 130 to 20).
It can be cured at 0 ° C. for 10 minutes to 1 hour).

[0033]

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.

[0034]

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 and 2, Comparative Examples 1 to 3] A dimethylsiloxane unit consisting of 99.825 mol%, a methylvinylsiloxane unit consisting of 0.15 mol% and a dimethylvinylsiloxane unit consisting of 0.025 mol%, having an average degree of polymerization of 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 base compound A, electrified acetylene black (manufactured by Denki Kagaku Co., Ltd.), conductive zinc flower F
X (manufactured by Honjo Chemical Co., Ltd.), C-19A (manufactured by Shin-Etsu Chemical Co., platinum paste), C-19B (manufactured by Shin-Etsu Chemical Co., organohydrogenpolysiloxane paste) as a curing agent
Was blended in the proportion shown in Table 1.

Next, using a 40 mm extruder, Table 1
The above material was extruded onto a metal (SUS) shaft having a diameter of 6 mm under the extrusion pressure shown in (1) to obtain a roll having a diameter of 20 mm. This roll was subjected to primary vulcanization at 200 ° C. for 30 minutes, 2
After secondary vulcanization at 00 ° C. for 4 hours, electric resistance was measured using the apparatus shown in FIG. For the measurement, roll 1 and electrode 2 of 7 mm
And the electrical resistance between the electrode 2 and the core metal 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.

[0038]

[Table 1]

From the results shown in Table 1, it was confirmed that the semiconductive rolls (Examples) obtained by the production 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 (72) Inventor Satao Hirabayashi 1 Hitomi, Oita, Matsuida-cho, Usui-gun, Gunma 10 Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory

Claims (2)

[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) a curing agent 0.1 to 5 parts by weight of a silicone rubber composition is pressed onto the surface of the core metal.
Outlet pressure is 70 kgf / cm²Half-molded and vulcanized below
Characterized by forming a conductive roll-shaped silicone rubber layer
And a method for manufacturing a semiconductive roll. 2. The plasticity of the silicone rubber composition (JIS
C-2123, Williams plasticity) is 100 to 30
The method for producing a semiconductive roll according to claim 1, wherein the method is 0.