JPH07207163A - Silicone rubber composition for fluororesin-coated fixing roll - Google Patents

Abstract

PURPOSE:To obtain a silicone rubber composition for forming a fluororesin- coated fixing roll suitable for electrophotographic copying machine, printer, etc. CONSTITUTION:This silicone rubber composition is composed of (A) 100 pts.-wt. of a diorganopolysiloxane having at least one Si-bonded alkenyl group on the side chain of molecular chain and at least three Si-bonded alkenyl groups in one molecule, (B) 10-1,000 pts.wt. of a diorganopolysiloxane having <=2 (0.5-1.5 on an average) Si-bonded hydrogen atoms in one molecule, (C) an organopolysiloxane having at least two Si-bonded hydrogen atoms in one molecule (the amount of the component C is 0.5-20mol in terms of the Si-bonded hydrogen atom in the component C based on 1mol of the Si-bonded alkenyl group in the component A and the component B in total) and (D) a catalytic amount of a platinum-based catalyst.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicone rubber composition for a fluororesin-coated fixing roll, and more specifically, it has a silicone rubber layer having a low hardness and a low compression set on the outer peripheral surface of a roll shaft. The present invention relates to a silicone rubber composition having a fluororesin layer on the outer peripheral surface of a rubber layer for forming a fluororesin-coated fixing roll suitable for electrophotographic copying machines, printers and the like.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic copying machine, there is a contact heat fixing system in which a toner image formed on the surface of a photoconductor is transferred onto a transfer sheet, and then the toner image is fixed onto the transfer sheet by a fixing roll to make a copy. Widely adopted. In the electrophotographic copying machine of this type, the fixing roll is required to have high toner releasability in order to obtain a clear image.

A conventional fixing roll having only a silicone rubber layer on the outer peripheral surface of a metal roll shaft does not have sufficient toner releasability, and as a fixing roll having excellent toner releasability, a metal roll shaft A number of fluororesin-coated fixing rolls have been proposed in which an elastic layer made of silicone rubber is formed on the outer peripheral surface and the elastic layer is coated with a hard layer made of fluororesin (Japanese Patent Laid-Open No. 53-74436). Japanese Laid-Open Patent Publication No. 57-89785, Japanese Utility Model Laid-Open No. 58-15.
7351, JP-A-59-74578 and JP-A-59-52269).

[0004]

However, since the hardness of the fluororesin is relatively high, the hardness of the fluororesin-coated fixing roll is considerably higher than that of the conventional fixing roll, and the repulsion of the fixing roll itself is high. Since the elasticity decreases, if such a fluororesin-coated fixing roll is used,
There has been a problem that wrinkles occur on transfer paper having an uneven thickness, such as an envelope.

Therefore, although silicone rubber having a relatively low hardness is used as the silicone rubber forming the elastic layer between the fluororesin and the metal roll shaft, it was used as the fluororesin-coated fixing roll. In this case, there has been a problem that the impact resilience is deteriorated due to repeated deformation and deterioration due to creep is caused.

The present inventors have arrived at the present invention as a result of extensive studies to solve the above problems.

That is, an object of the present invention is to provide a silicone rubber composition for forming a fluororesin-coated fixing roll suitable for electrophotographic copying machines, printers and the like.

[0008]

The present invention provides (A) at least one silicon atom-bonded alkenyl group in a side chain of a molecule, and at least three silicon atom-bonded alkenyl groups in one molecule. Group-containing diorganopolysiloxane
100 parts by weight, (B) having 2 or less silicon atom-bonded alkenyl groups at the end of the molecular chain and having an average value of 0.5 to
Diorganopolysiloxane having 1.5 and not having a silicon atom-bonded alkenyl group in the side chain of the molecular chain
10 to 1000 parts by weight of (C) the organopolysiloxane having at least two silicon-bonded hydrogen atoms in one molecule {(C) component is mixed in the (A) component
0.5 mol of the silicon atom-bonded hydrogen atoms in the component (C) per 1 mol of the total silicon atom-bonded alkenyl groups in the component (B).
The amount is about 20 mol. } And (D) a composition comprising a catalytic amount of a platinum-based catalyst, wherein a silicone rubber obtained by curing the composition has a JIS A hardness of 10 or less specified in JIS K 6301 and a compression set. Is 15% or less, the present invention relates to a silicone rubber composition for a fluororesin-coated fixing roll, which has a silicone rubber layer on the outer peripheral surface of the roll shaft and a fluororesin layer on the outer peripheral surface of the silicone rubber layer.

The silicone rubber composition for a fluororesin-coated fixing roll of the present invention will be described in detail.

The component (A), a diorganopolysiloxane, is the main ingredient of the present composition and is a component for reducing the compression set of the silicone rubber obtained by curing the present composition. The component (A) is required to have at least one silicon atom-bonded alkenyl group in the side chain of the molecular chain and at least three silicon atom-bonded alkenyl groups in one molecule. The silicon-bonded alkenyl group having at least one silicon atom in the chain can reduce the compression set of the silicone rubber obtained by curing the composition. Specific examples of the silicon atom-bonded alkenyl group in the component (A) include vinyl group, allyl group, butenyl group, pentenyl group, hexenyl group and heptenyl group, and vinyl group is preferable. Further, as the silicon atom-bonded organic group other than the silicon atom-bonded alkenyl group in the component (A), specifically, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group or a hexyl group; a phenyl group , Aryl groups such as tolyl group and xylyl group; aralkyl groups such as benzyl group and phenethyl group; 3-
Halo-substituted alkyl groups such as chloropropyl group and 3,3,3-trifluoropropyl group are exemplified, and methyl group and phenyl group are preferable. The viscosity of the component (A) is not particularly limited, and for example, the viscosity at 25 ° C. is preferably 1,000 centipoise or more,
It is preferably in the range of 00 to 500,000 centipoise.

Specific examples of the diorganopolysiloxane of the component (A) include a dimethylsiloxy / methylvinylsiloxane copolymer capped with trimethylsiloxy groups at both ends of the molecular chain, and a methylvinylpolyblocked with trimethylsiloxy groups at both ends of the molecular chain. Siloxane, molecular chain both ends trimethylsiloxy group blocked methyl vinyl siloxane / methylphenyl siloxane copolymer, molecular chain both ends trimethyl siloxy group blocked dimethyl siloxane / methyl vinyl siloxane
Methylphenyl siloxane copolymer, dimethylvinylsiloxy group-blocked dimethylvinylsiloxy group copolymer at both molecular chain ends, dimethylvinylsiloxy group-blocked methylvinylpolysiloxane at both molecular chain ends, dimethylvinylsiloxy group-blocked methyl at both molecular chain ends Vinyl siloxane / methyl phenyl siloxane copolymer, dimethyl vinyl siloxy group-capped dimethyl siloxane / methyl vinyl siloxane / methyl phenyl siloxane copolymer, molecular chain both ends silanol group dimethyl siloxane / methyl vinyl siloxane copolymer, Examples include silanol group-blocked methylvinylpolysiloxane having silanol groups at both ends of the molecular chain, and dimethylsiloxane / methylvinylsiloxane / methylphenylsiloxane copolymers having silanol groups at both ends of the molecular chain.

The component (B) diorganopolysiloxane is
It is a component for lowering the hardness of the silicone rubber obtained by curing the composition and for not deteriorating the compression set. The component (B) has not more than 2 silicon atom-bonded alkenyl groups at the end of the molecular chain and has an average value of 0.5 to 1.5.
It is necessary that the number of the alkenyl groups is a number and that the side chain of the molecular chain does not have a silicon atom-bonded alkenyl group. Specific examples of the silicon atom-bonded alkenyl group in the component (B) include a vinyl group, an allyl group, a butenyl group, a pentenyl group, a hexenyl group and a heptenyl group, and a vinyl group is preferable. Further, as the silicon atom-bonded organic group other than the silicon atom-bonded alkenyl group in the component (B), specifically, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group or a hexyl group; a phenyl group , Aryl groups such as tolyl group and xylyl group; aralkyl groups such as benzyl group and phenethyl group; halo-substituted alkyl groups such as 3-chloropropyl group, 3,3,3-trifluoropropyl group and the like, preferably methyl. Group, a phenyl group. The viscosity of the component (B) is not particularly limited, and for example, the viscosity at 25 ° C is 5
It is preferably at least 00 centipoise and more preferably within the range of 1,000 to 100,000 centipoise.

The method for preparing the diorganopolysiloxane of the component (B) is not particularly limited. For example, a dimethylpolysiloxane capped with dimethylvinylsiloxy groups at both ends of the molecular chain and a dimethylpolysiloxane capped with trimethylsiloxy groups at both ends of the molecular chain. A method of carrying out a re-equilibration reaction with siloxane in the presence of an acidic catalyst such as activated clay or an alkaline catalyst such as potassium hydroxide can be mentioned.

As such a diorganopolysiloxane of the component (B), specifically, a dimethylpolysiloxane whose molecular chain ends are blocked with trimethylsiloxy groups and other molecular chain ends are blocked with dimethylvinylsiloxy groups. , Methylphenylpolysiloxane whose molecular chain ends are blocked with trimethylsiloxy groups and other molecular chain ends are blocked with dimethylvinylsiloxy groups, molecular chain ends are blocked with trimethylsiloxy groups, and other molecular chain ends are Dimethylsiloxane / methylphenylsiloxane copolymer blocked with dimethylvinylsiloxy groups, dimethylpolysiloxane with both ends of the molecular chain blocked with trimethylsiloxy groups, and dimethylpolysiloxane with both ends of the molecular chain blocked with dimethylvinylsiloxy groups With an acidic or alkaline catalyst. The dimethylpolysiloxane mixture obtained by the oxidization reaction, a dimethylpolysiloxane whose both molecular chain ends are blocked with trimethylsiloxy groups and a methylphenylpolysiloxane whose both molecular chain ends are blocked with dimethylvinylsiloxy groups are used as an acidic catalyst or Dimethyl siloxane-methyl phenyl siloxane copolymer mixture obtained by re-equilibration reaction with an alkaline catalyst, methyl phenyl polysiloxane with both ends of the molecular chain blocked with trimethylsiloxy groups and dimethyl vinyl siloxy groups at both ends of the molecular chain An example is a dimethylsiloxane / methylphenylsiloxane copolymer mixture obtained by re-equilibrating the blocked dimethylpolysiloxane with an acidic catalyst or an alkaline catalyst.

In this composition, the compounding amount of the component (B) is
It is necessary to be in the range of 10 to 1000 parts by weight, preferably 10 to 20 parts by weight, relative to 100 parts by weight of the component (A).
Within the range of 0 parts by weight. This is because when the amount of the component (B) blended is less than 10 parts by weight relative to 100 parts by weight of the component (A), the JIS value specified in JIS K 6301 after curing is determined.
A silicone rubber composition for forming a silicone rubber having an SA hardness of 10 or less cannot be prepared,
Further, this is because the fluorine resin-coated fixing roll using such a silicone rubber composition causes wrinkles on the transfer paper when the transfer paper such as an envelope is used.
If it exceeds 0 part by weight, a silicone rubber composition for forming a silicone rubber having a compression set of 15% or less as specified in JIS K6301 after curing cannot be prepared, and such a silicone rubber cannot be prepared. This is because the rubber composition will not cure sufficiently and the fixing roll cannot be formed.

The organopolysiloxane as the component (C) acts as a cross-linking agent for curing the composition, and must have at least two silicon-bonded hydrogen atoms in one molecule, preferably The number of hydrogen atoms bonded to silicon atoms is within the range of 2 to 6 in one molecule. The bonding position of the silicon atom-bonded hydrogen atom in the component (C) is not particularly limited, and examples thereof include a molecular chain terminal, a molecular chain side chain, and a molecular chain terminal and a molecular chain side chain. Specific examples of the silicon atom-bonded organic group in the component (C) include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group and hexyl group; phenyl group, tolyl group, xylyl group, etc. Aryl group; aralkyl group such as benzyl group and phenethyl group; 3-
Halo-substituted alkyl groups such as chloropropyl group and 3,3,3-trifluoropropyl group are exemplified, and methyl group and phenyl group are preferable. Further, the molecular structure of the component (C) is not particularly limited, and specific examples thereof include linear, partially branched linear, branched, and reticulated, and preferably linear.
It is straight-chain with some branches. The viscosity of the component (C) is not particularly limited, and for example, the viscosity at 25 ° C is 3 to
It is preferably in the range of 10,000 centipoise, and more preferably in the range of 3 to 300 centipoise.

Specific examples of the organopolysiloxane of the component (C) include methylhydrogenpolysiloxane blocked with trimethylsiloxy groups at both ends of the molecular chain, and dimethylsiloxane blocked with trimethylsiloxy groups at both ends of the molecular chain.
Methyl hydrogen siloxane copolymer, molecular chain both ends trimethylsiloxy group blocked methyl hydrogen siloxane / methyl phenyl siloxane copolymer, molecular chain both ends trimethyl siloxy group blocked dimethyl siloxane / methyl hydrogen siloxane / methyl phenyl siloxane copolymer , Dimethylpolysiloxane with dimethylhydrogensiloxy group blocked at both ends of the molecular chain, methylhydrogenpolysiloxane with dimethylhydrogensiloxy group blocked at both ends of the molecular chain, dimethylsiloxane / methylhydrogensiloxane copolyester with dimethylhydrogensiloxy group blocked at both ends of the molecular chain Copolymerization, dimethylhydrogensiloxy group-capped dimethylhydrogensiloxysiloxane copolymer at both ends of the molecular chain Xyl group-blocked methylphenylpolysiloxane, molecular chain both-end silanol group-blocked methylhydrogenpolysiloxane, molecular chain both-end silanol group-blocked dimethylsiloxane-methylhydrogensiloxane copolymer, molecular chain both-end silanol group-blocked methylhydrogensiloxane Examples thereof include a methylphenylsiloxane copolymer, a silanol group-capped dimethylsiloxane having both molecular chain terminals, a methylhydrogensiloxane, and a methylphenylsiloxane copolymer.

In this composition, the compounding amount of the component (C) is
The amount is such that the silicon atom-bonded hydrogen atoms in the component (C) are within the range of 0.5 to 20 mols per 1 mol of the total silicon atom-bonded alkenyl groups in the component (A) and the component (B). It is necessary, and the amount is preferably in the range of 0.8 to 3 mol. This is because the amount of component (C) is the same as that in component (A).
When the amount of the silicon atom-bonded hydrogen atoms of the component (C) is less than 0.5 mol based on 1 mol of the total silicon atom-bonded alkenyl groups in the component (B), the obtained composition cannot be sufficiently cured. The reason is that a good fixing roll cannot be formed, and if the amount is more than 20 mol, the composition obtained easily foams during curing, and the mechanical strength of the silicone rubber obtained by curing is high. This is because it is small and the heat resistance is significantly reduced.

The platinum catalyst as the component (D) is a catalyst for accelerating the curing of the present composition, and generally known compounds can be used as catalysts for hydrosilylation reaction. Specific examples of the component (D) include platinum black, platinum-supported alumina powder, platinum-supported silica powder, platinum-supported carbon powder, chloroplatinic acid, alcohol solution of chloroplatinic acid, chloroplatinic acid and olefin. And a complex of chloroplatinic acid and vinyl siloxane, and the platinum-based catalysts of these examples are dispersed in a thermoplastic organic resin such as methyl methacrylate resin, polycarbonate resin, polystyrene resin, or silicone resin in the form of fine particles. Platinum-based catalysts are exemplified.

In the present composition, the blending amount of the component (D) is a catalytic amount and is not particularly limited and may be an amount sufficient to cure the composition of the present invention. For example, the components (A) and (B It is preferable that the amount of platinum metal in the component (D) is within the range of 0.1 to 500 parts by weight, and more preferably 1 ~
The amount is within the range of 50 parts by weight.

The silicone rubber composition for a fluororesin-coated fixing roll of the present invention can be obtained by uniformly blending the above-mentioned components (A) to (D), and the storage stability of the obtained composition is improved. As an optional component for improving the handling workability, an acetylene compound such as 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyne-3-ol, phenylbutynol An enyne compound such as 3-methyl-3-penten-1-yne, 3,5-dimethyl-3-hexene-1-yne; 1,3,5,7
-Tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, 1,3,5,7-tetramethyl-
A curing inhibitor such as triazoles such as 1,3,5,7-tetrahexenylcyclototrasiloxane and benzotriazole, phosphines, mercaptans and hydrazines can be blended. The compounding amount of these curing inhibitors is preferably in the range of 0.001 to 5 parts by weight with respect to 100 parts by weight of the component (A).

Further, the silicone rubber composition for the fixing roll of the fluororesin of the present invention may contain an inorganic filler as an optional component for improving the mechanical strength of the silicone rubber obtained by curing. . Examples of the inorganic filler that can be added to the composition include precipitated silica fine powder, fumed silica fine powder, calcined silica fine powder, fumed titanium oxide fine powder, ground quartz fine powder, diatomaceous earth fine powder, Aluminosilicic acid fine powder, iron oxide fine powder, zinc oxide fine powder, calcium carbonate fine powder, and carbon black are exemplified. Furthermore, these inorganic fillers are surface-treated with an organosilicon compound such as organoalkoxysilane, organochlorosilane, or organodisilazane. Examples include treated inorganic fillers. The blending amount of these inorganic fillers is preferably 50 parts by weight or less with respect to 100 parts by weight of the component (A).

The silicone rubber composition for a fluororesin-coated fixing roll of the present invention comprises the above-mentioned components (A) to (D) and, if necessary, the above-mentioned optional components such as a two-roll, knee mixer, Ross mixer and the like. It can be prepared by uniformly mixing by a known kneading means. The thus obtained fluororubber-coated silicone rubber composition for a fixing roll of the present invention has a JIS A hardness of 10 or less according to JIS K 6301 of a silicone rubber obtained by curing the composition, and is compressed. It is necessary that the permanent strain rate is 15% or less. This is JIS K 6301
When a silicone rubber having a JIS A hardness of more than 10 specified in 1 is used for a fluororesin-coated fixing roll, the obtained fixing roll is liable to cause wrinkles on a transfer sheet having an uneven thickness such as an envelope. Yes, JIS
When a silicone rubber having a compression set of more than 15% specified in K 6301 is used for a fluororesin-coated fixing roll, the resulting fixing roll has a reduced rebound resilience due to repeated deformation and is deteriorated due to creep. This is because.

The silicone rubber composition for a fluororesin-coated fixing roll of the present invention can be molded by a known apparatus and method used for producing a conventional fixing roll. For example, a metal roll shaft made of iron, aluminum, or the like is placed inside the roll forming die, and the inner wall of the roll forming die preferably has a thickness of 0.1 mm or less, and more preferably Is 0.1 to 50
A fluororesin tube of μm tetrafluoroethylene resin, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene / hexafluoropropylene copolymer, etc. is placed, and then the metal inside the mold is placed. The fluororesin-coated fixing roll can be molded by injecting the fluororesin-coated silicone rubber composition for fixing roll between the roll shaft and the fluororesin tube and then curing the composition.
At this time, the thickness of the silicone rubber layer is not particularly limited, and is preferably 2 to 30 mm, for example. Further, in order to improve the adhesiveness between the metal roll shaft and the cured silicone rubber, it is preferable that the outer peripheral surface of the metal roll shaft is previously treated with a known primer. As a method of injecting and curing the silicone rubber composition inside the mold, a compression molding machine, a transfer molding machine, or an injection molding machine, which is usually used in the molding method of a liquid silicone rubber composition, can be used. At this time, if the curing temperature of the silicone rubber composition is too low, the curing rate of the composition will be slow and productivity will be reduced, and if the curing temperature is too high, the silicone rubber composition after removal from the mold will be Since the curing shrinkage becomes large and wrinkles easily occur in the fluororesin, the curing temperature is preferably in the range of 50 to 220 ° C, and more preferably in the range of 100 to 170 ° C.

[0025]

EXAMPLES The silicone rubber composition for a fluororesin-coated fixing roll of the present invention will be described in detail with reference to Examples. In addition,
In the examples, the viscosity value is a value measured at 25 ° C. Further, the evaluation of the silicone rubber and the fluororesin-coated fixing roll was performed as follows.

○ Hardness of Silicone Rubber A silicone rubber composition for a fluororesin-coated fixing roll was prepared as follows.
The hardness of the silicone rubber obtained by heating at 20 ° C for 30 minutes and then at 200 ° C for 4 hours was measured according to JISK 630.
It was measured by the JIS A hardness meter described in 1. -Measurement of compression set of silicone rubber 1 piece of silicone rubber composition for fluororesin-coated fixing roll
The compression set of the silicone rubber obtained by heating at 20 ° C for 30 minutes and then at 200 ° C for 4 hours was measured by JIS.
It was measured by the method described in K 6301. However, the heat treatment temperature was 180 ° C., and the heat treatment time was 22 hours. ○ Hardness of fluororesin-coated fixing roll The hardness for fluororesin-coated fixing roll is JIS K 63.
The hardness was measured by the JIS A hardness meter described in No. 01.

The diorganopolysiloxanes used in the examples and comparative examples are as follows. ○ Diorganopolysiloxane (I) Formula:

[Chemical 1] Which has a viscosity of 40,000 centipoise and a dimethylvinylsiloxy group-blocked dimethylvinylsiloxy group-capped molecular chain terminal. ○ Diorganopolysiloxane (II) Formula:

[Chemical 2] And a viscosity of 40,000 centipoise, a dimethylsiloxane capped with trimethylsiloxy groups at both ends of the molecular chain.
Methyl vinyl siloxane copolymer. ○ Diorganopolysiloxane (III) formula:

[Chemical 3] Which has a viscosity of 40,000 centipoise and is a dimethylpolysiloxane endblocked by dimethylvinylsiloxy groups at both molecular chain ends. ○ Diorganopolysiloxane (IV) average unit formula:

[Chemical 4] And dimethyl polysiloxane having a viscosity of 2,000 centipoise. ○ Diorganopolysiloxane (V) average unit formula:

[Chemical 5] And dimethylpolysiloxane having a viscosity of 10,000 centipoise.

Example 1 100 parts by weight of diorganopolysiloxane (I), 20 parts by weight of diorganopolysiloxane (IV) in a Ross mixer, and fumed silica having a specific surface area of 200 m ² / g surface-treated with dimethyldichlorosilane. Fine powder 5 parts by weight and finely ground quartz fine powder 4 having an average particle size of 5 μm
0 part by weight was added, and the mixture was mixed until uniform. Then, the composition was mixed under reduced pressure at 170 ° C. for 2 hours. Then, after cooling the composition, the composition is of the formula:

[Chemical 6] Represented by the following formula: 3.5 parts by weight of a dimethylsiloxy-methylhydrogensiloxane copolymer capped with trimethylsiloxy groups at both ends of the molecular chain; 0.5 part by weight of a chloroplatinic acid solution in isopropyl alcohol (platinum content = 1% by weight); After 1 part by weight of phenylbutynol was added, this composition was uniformly mixed to prepare a silicone rubber composition for a fluororesin-coated fixing roll of the present invention. The silicone rubber obtained by curing this composition had a hardness of 7 and a compression set of 12%.

A commercially available primer (manufactured by Toray Dow Corning Silicone Co., Ltd .; trade name DY39-051A / B primer) was uniformly applied to the peripheral surface of a cylindrical iron roll core having a diameter of 10 mm, and the primer layer was sufficiently dried. It was
In addition, a commercially available primer (Toray Dow Corning Silicone Co., Ltd .; trade name DY39-067 primer) was uniformly applied to the inner surface of a tetrafluoroethylene resin tube having a film thickness of 50 μm and the inner surface of which was treated with an alkali, and then the primer layer It was dried sufficiently. Then, the roll core metal is placed inside the roll forming die and the tetrafluoroethylene resin tube is placed on the inner wall of the die, and the silicone rubber composition is injected into the cavity.
Heat at 30 ° C. for 30 minutes. Then, take out the fixing roll having a thickness of 10 mm coated with tetrafluoroethylene resin,
This was heated in a hot air circulation oven at 200 ° C. for 4 hours. Then, it was cooled. The hardness of the fixing roll coated with tetrafluoroethylene resin was 19.

This tetrafluoroethylene resin-coated fixing roll was mounted on an electrophotographic copying machine, and the temperature was adjusted to 1 at 180 ° C.
When left for 00 hours and continuously copied to the envelopes, no wrinkle was observed in any of the envelopes, and the copied image was clear.

Comparative Example 1 A fluororesin-coated fixing roll silicone rubber composition for comparison was prepared in the same manner as in Example 1 except that the diorganopolysiloxane (IV) was not used. . The silicone rubber obtained by curing this composition had a hardness of 10 and a compression set of 8%. Further, in the same manner as in Example 1, a tetrafluoroethylene resin-coated fixing roll was prepared from this silicone rubber composition for a fluorine resin-coated fixing roll. The hardness of this fixing roll was 25. When this tetrafluoroethylene resin-coated fixing roll was mounted in an electrophotographic copying machine, left standing in an atmosphere of 180 ° C. for 100 hours, and then continuously copied to an envelope, occurrence of wrinkles was observed in the envelope at a rate of 5%.

Comparative Example 2 100 parts by weight of diorganopolysiloxane (III), 20 parts by weight of diorganopolysiloxane (IV) in a Ross mixer, and fumed silica having a specific surface area of 200 m ² / g surface-treated with dimethyldichlorosilane. 5 parts by weight of fine powder and 40 parts by weight of finely ground quartz powder having an average particle size of 5 μm were added and mixed until uniform, and the composition was mixed under reduced pressure at 170 ° C. for 2 hours. Then, after cooling the composition, the composition is of the formula:

[Chemical 7] Represented by the following formula: 2.1 parts by weight of a dimethylsiloxane / methylhydrogensiloxane copolymer having trimethylsiloxy groups blocked at both molecular chain ends, 0.5 parts by weight of a chloroplatinic acid isopropyl alcohol solution (platinum content = 1% by weight), and After adding 1 part by weight of phenylbutynol, this composition was uniformly mixed to prepare a silicone rubber composition for a fixing roll of the present invention. The silicone rubber obtained by curing this composition had a hardness of 6 and a compression set of 25%. Further, in the same manner as in Example 1, a tetrafluoroethylene resin-coated fixing roll was prepared from this silicone rubber composition for a fluorine resin-coated fixing roll. The hardness of this fixing roll was 19. Attach this tetrafluoroethylene resin coated fixing roll to an electrophotographic copying machine,
When left in an atmosphere of 180 ° C. for 100 hours, permanent distortion was observed on this fixing roll, and it was observed that image unevenness occurred in the copied image.

Example 2 100 parts by weight of diorganopolysiloxane (II), 50 parts by weight of diorganopolysiloxane (V) in a Ross mixer, and fumed silica having a specific surface area of 200 m ² / g surface-treated with dimethyldichlorosilane. 7 parts by weight of fine powder and 50 parts by weight of pulverized quartz fine powder were added,
After mixing until uniform, the composition is placed under reduced pressure at 170 ° C.
And mixed for 2 hours. Then, after cooling the composition,
This composition has the formula:

[Chemical 8] Represented by the following formula, 4 parts by weight of a dimethylsiloxy-methylhydrogensiloxane copolymer capped with trimethylsiloxy groups at both ends of the molecular chain, 0.5 part by weight of a solution of chloroplatinic acid in isopropyl alcohol (platinum content = 1% by weight) and 0 of pyrazine. After adding 1 part by weight, the composition was uniformly mixed to prepare a silicone resin composition for a fluororesin-coated fixing roll of the present invention. The silicone rubber obtained by curing this composition has a hardness of 3 and a compression set of 8%.
Met.

A tetrafluoroethylene resin-coated fixing roll was prepared in the same manner as in Example 1 by using the silicone rubber composition for a fluorine resin-coated fixing roll. The hardness of this fixing roll was 15. This tetrafluoroethylene-coated fixing roll was mounted on an electrophotographic copying machine,
After leaving it in the atmosphere for 100 hours, it was continuously copied to an envelope. No wrinkles were found in any envelope.
The reproduced image was clear.

Comparative Example 3 100 parts by weight of diorganopolysiloxane (III), 50 parts by weight of diorganopolysiloxane (V) in a Ross mixer, and fumed silica having a specific surface area of 200 m ² / g surface-treated with dimethyldichlorosilane. 7 parts by weight of fine powder and 50 parts by weight of finely ground quartz powder having an average particle size of 5 μm were added and mixed until uniform, and then the composition was mixed under reduced pressure at 170 ° C. for 2 hours. Then, after cooling the composition, the composition is of the formula:

[Chemical 9] Represented by the following formula: 3 parts by weight of a dimethylsiloxy-methylhydrogensiloxane copolymer capped with trimethylsiloxy groups at both ends of the molecular chain, 0.5 part by weight of a solution of chloroplatinic acid in isopropyl alcohol (platinum content = 1% by weight) and 0 of pyrazine. After adding 1 part by weight, the composition was uniformly mixed to prepare a silicone resin composition for a fluororesin-coated fixing roll of the present invention. The silicone rubber obtained by curing this silicone rubber composition had a hardness of 5 and a compression set of 25%. Further, in the same manner as in Example 1, a tetrafluoroethylene resin-coated fixing roll was prepared from this silicone rubber composition for a fluorine resin-coated fixing roll. The hardness of this fixing roll was 16. When this tetrafluoroethylene-coated fixing roll was mounted on an electrophotographic copying machine and left standing in an atmosphere of 180 ° C. for 100 hours, permanent distortion was observed on this fixing roll, and it was observed that image unevenness occurred in the copied image. Was done.

[0036]

The silicone rubber composition for a fluororesin-coated fixing roll of the present invention comprises components (A) to (D),
Since the silicone rubber after curing has a low hardness and a low compression set, the fluororesin-coated fixing roll obtained using the silicone rubber has excellent toner releasability and is not uniform in thickness. It has a feature that wrinkles are less likely to occur.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akito Nakamura 2-2 Chikusaigan, Ichihara-shi, Chiba Toray Dow Corning Silicone Co., Ltd.

Claims (1)

[Claims] 1. A diorganopolysiloxane having (A) at least one silicon-bonded alkenyl group in a side chain of a molecular chain and at least three silicon-bonded alkenyl groups in one molecule.
0 part by weight, (B) having 2 or less silicon atom-bonded alkenyl groups at the end of the molecular chain, the average value of which is 0.5 to 1.5, and the side chains of the molecular chain have silicon atom-bonded alkenyl groups. Free diorganopolysiloxane
10 to 1000 parts by weight, (C) at least 2 in one molecule
The amount of the organopolysiloxane having silicon atom-bonded hydrogen atoms {(C) component is 1 mol of the total silicon atom-bonded alkenyl groups in the component (A) and the component (B)).
The amount is such that the silicon atom-bonded hydrogen atoms in the component (C) are 0.5 to 20 mol. } And (D) a composition comprising a catalytic amount of a platinum-based catalyst, and a silicone rubber obtained by curing the composition according to JIS K 6301
A hardness is 10 or less and a compression set is 15% or less, and a silicone rubber layer is provided on the outer peripheral surface of the roll shaft, and a fluororesin layer is provided on the outer peripheral surface of the silicone rubber layer. A fluororubber-coated silicone rubber composition for a fixing roll having the same.