JP4697493B2 - Method for improving compression set resistance of low thermal conductive silicone rubber for heat fixing roll - Google Patents

Description

  The present invention relates to a method for improving the compression set resistance of a low thermal conductive silicone rubber for a heat fixing roll used as a heat fixing roll of a heat fixing apparatus in an electrostatic recording apparatus such as an electrophotographic copying machine, a printer, a facsimile machine or the like. is there.

  Heat-curable liquid silicone rubber is used in various fields because it is excellent in moldability and excellent in heat resistance and electrical insulation after molding. Among them, it is used for fixing rolls such as PPC, LBP, and FAX because of its excellent heat resistance and releasability.

  In an apparatus using these electrophotographic processes, it is necessary to fix the toner image transferred from the surface of the photoreceptor to the copy paper on the copy paper. As a method for fixing the toner image, there is a wide range of methods in which the copy paper is passed between a heated heater roll and a pressure roll, which are pressed against each other, and the toner image on the copy paper is thermally fused and fixed. It has been adopted. In this heat-sealing method, it is possible to make a copier, printer, etc. that responds quickly by increasing the thermal conductivity of the roll material. On the other hand, materials with low thermal conductivity, that is, good heat storage properties are required in the trend toward reduction in price and price.

  As such a material, there is a silicone rubber foam using low thermal conductivity of gas, and there are a method of adding a pyrolytic foaming agent and a method of using hydrogen gas by-produced during curing. However, the method of adding a pyrolytic foaming agent is considered to have problems of toxicity and odor of the decomposition gas, and in the case of using a platinum catalyst as a curing catalyst, the inhibition of curing by the foaming agent is a problem. It was.

  Further, the method using hydrogen gas produced as a by-product at the time of curing has problems such as the explosive nature of hydrogen gas and the need to handle the uncured product during storage. Furthermore, in the molding in which foaming is performed in a mold like injection molding, there is a problem that it is difficult to obtain a silicone rubber foam having fine and uniform cells.

  As a method for solving such a problem, a method of adding a hollow filler made of an organic resin is also known (see Patent Documents 1 and 2: JP-A Nos. 2000-143986 and 2001-220510), Although it is effective to obtain uniform bubbles, there is a problem that the hardness of the molded cured product and the variation in compression set are increased.

JP 2000-143986 A JP 2001-220510 A

  This invention is made | formed in view of the said situation, and it aims at providing the method of improving the compression set resistance of the low heat conductive silicone rubber for heat fixing rolls with small heat conductivity without said problem. .

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that when a silicone rubber sponge is obtained by blending a hollow filler made of an organic resin, the average particle diameter is 5 parts by weight in 100 parts by mass of the organopolysiloxane. A hollow filler made of an organic resin having a wide particle size distribution, having a total particle size of 20 to 70% by mass with a particle size of 30 to 200 % and an average particle size of 30% or more smaller than the average particle size. It has been found that a silicone rubber composition containing 0.3 to 100 parts by mass can provide a low thermal conductive silicone rubber having a small compression set and a small rubber hardness and variation in compression set. It is.

Accordingly, the present invention provides the following method for improving the compression set resistance of the low thermal conductive silicone rubber for heat fixing rolls.
Claim 1:
A method for reducing the compression set of the low heat conductive silicone rubber in a heat fixing roll in which a low heat conductive silicone rubber layer is formed on a core metal, which bonds to at least two silicon atoms in one molecule. Particles having an average particle diameter of 5 to 200 μm and 30% or more smaller than the average particle diameter in 100 parts by mass of an organopolysiloxane containing an alkenyl group and a curing effective amount of a curing agent for curing the organopolysiloxane A silicone rubber composition containing 0.3 to 100 parts by mass of a hollow filler made of an organic resin having a wide particle size distribution with a total particle size of 20 to 70% by mass and a particle size larger than 30% by mass. A method for improving the compression set resistance of a low heat conductive silicone rubber for a heat fixing roll, characterized in that a low heat conductive silicone rubber is obtained.
Claim 2:
Further, a silicone rubber composition containing 1 to 30 parts by mass of polyether, polyhydric alcohol or derivative thereof with respect to 100 parts by mass of organopolysiloxane containing an alkenyl group bonded to at least two silicon atoms in one molecule. The method according to claim 1, wherein
Claim 3:
The method according to claim 1 or 2, wherein the true specific gravity of the hollow filler is 0.01 to 1.0 .
Claim 4:
The hollow filler is formed of a polymer of a monomer selected from vinylidene chloride, acrylonitrile, methacrylonitrile, acrylic acid ester and methacrylic acid ester, or a copolymer of two or more of the above monomers. Or the method of 3.
Claim 5:
The method according to any one of claims 1 to 4, wherein the thermal conductivity after curing is 0.05 to 0.15 W / m · ° C.
Claim 6:
The method according to any one of claims 1 to 5, which comprises curing by any one of injection molding, compression molding, injection molding and coating.
Claim 7:
The method according to any one of claims 1 to 6, comprising curing at 100 to 300 ° C for 10 seconds to 1 hour.
Claim 8:
The method according to any one of claims 1 to 7, further comprising post-curing at 120 to 250 ° C for 30 minutes to 70 hours after molding.

  According to the present invention, by blending a hollow filler having a wide particle size distribution, it is possible to obtain a silicone rubber composition having a small compression set and a small rubber hardness due to molding and lots and small variations in compression set. In addition, this increases heat storage and reduces heat diffusion, resulting in excellent energy savings and a compact device. Applying this to a heat fixing roll is useful for reducing the size and cost of fixing devices. It is.

  In the thermosetting organopolysiloxane composition, the silicone rubber composition for a heat fixing roll of the present invention has an average particle size of 200 μm or less and a particle size smaller by 30% or more than the average particle size, % Of organic resin hollow fillers having a wide particle size distribution, the total of which is 20% by mass or more with a particle size of at least%.

  Here, the hollow filler made of organic resin has a gas portion in the cured product, and reduces the thermal conductivity like sponge rubber. Vinylidene chloride, acrylonitrile, methacrylonitrile, acrylate ester and methacrylic ester It is preferably formed of a polymer of a monomer selected from acid esters or a copolymer of two or more of the above monomers. Moreover, what made the inorganic filler etc. adhere to the surface for the reason for giving the intensity | strength of a hollow filler, etc. may be used.

  In order to sufficiently reduce the thermal conductivity in the silicone rubber composition, the true specific gravity of the hollow filler is preferably 0.01 to 1.0, more preferably 0.02 to 0.5, More preferably, it is 0.02-0.3. If the true specific gravity is less than 0.01, not only is it difficult to mix and handle, but the pressure resistance of the hollow filler is insufficient and it may be destroyed at the time of molding, making it impossible to reduce the weight and decrease the thermal conductivity. On the other hand, if the true specific gravity is greater than 1.0, the thickness of the hollow filler shell is so large that the heat conduction may not be sufficiently reduced.

The average particle size of the hollow filler is 5 μm or more and 200 μm or less, preferably 5 μm or more and 150 μm or less, more preferably 20 μm or more and 120 μm or less. If the average particle size exceeds 200 μm, the hollow filler is destroyed by the injection pressure at the time of molding. As a result, problems such as increased heat conduction and increased surface roughness after roll forming occur. Moreover, if the average particle diameter is less than 5 μm, the encapsulated gas is insufficient and the desired low thermal conductivity may not be obtained.

Furthermore, in the present invention, it is important that the particle size distribution of the hollow filler is wide, and the total of particles having a particle size larger by 30% or more than the average particle size and particles having a particle size smaller by 30% or more (ie, When the average particle size is M μm, the total amount of particles having a particle size of 0.7 M μm or less and particles having a particle size of 1.3 M μm or more is 20 to 70% by mass , particularly 30 to 70% by mass. Preferably there is. If it is less than 20% by mass, the compression set of the cured product is large, or the physical properties of the cured product vary. More preferably, the total of particles having a particle size of 35% or more with respect to the average particle size and particles having a particle size of 35% or more is 20% by mass or more, particularly 30 to 60% by mass, based on the total amount.

  By blending such a hollow filler having a wide particle size distribution, it is possible to obtain a silicone rubber composition having a small compression set, a rubber hardness due to molding or a lot, and a small variation in compression set. Such a hollow filler having a wide particle size distribution can be obtained by appropriately mixing a hollow filler having a small average particle diameter and a hollow filler having a large average particle diameter. In addition, when using commercially available hollow fillers as they are, even if the same product is manufactured by the same manufacturer, the particle size distribution may vary depending on individual production lots. It is necessary to select and use specific lot products with a wide distribution from the production lot products.

The particle size distribution can be obtained as a cumulative weight average value D ₅₀ (or median diameter) or the like by a particle size distribution meter using an analysis means such as a laser beam diffraction method.

The blending amount of the hollow filler is 0.3 to 100 parts by mass, preferably 0.3 to 80 parts by mass with respect to 100 parts by mass of the organopolysiloxane as the component (A) of the following thermosetting organopolysiloxane composition. Parts, more preferably 0.5 to 50 parts by mass. If the amount is less than 0.1 parts by mass, the decrease in thermal conductivity is insufficient. If the amount exceeds 100 parts by mass, not only molding and blending are difficult, but also the molded product becomes brittle without rubber elasticity. Furthermore, it is preferable to mix | blend so that it may become 10 to 80% by a volume ratio in a silicone rubber composition (or hardened | cured material).

The thermosetting organopolysiloxane composition used in the present invention is:
(A) Organopolysiloxane containing an alkenyl group bonded to at least two silicon atoms in one molecule: 100 parts by mass
(B) Organohydrogenpolysiloxane containing at least two hydrogen atoms bonded to silicon atoms in one molecule: 0.1 to 50 parts by mass,
(C) addition reaction catalyst: catalyst amount,
(D) Polyether, polyhydric alcohol or derivative thereof: It is preferable to contain 0 to 30 parts by mass.

As the organopolysiloxane having at least two alkenyl groups on average in one molecule of the component (A), those represented by the following average composition formula (1) can be used.
R ¹ _a SiO _{(4-a) / 2} (1)
Wherein R ¹ is an unsubstituted or substituted monovalent hydrocarbon group having the same or different carbon number of 1 to 10, preferably 1 to 8, and a is 1.5 to 2.8, preferably 1 .8 to 2.5, more preferably a positive number in the range of 1.95 to 2.05.)

Here, as the unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, which is the same or different from each other represented by R ¹ , for example, a methyl group, an ethyl group, a propyl group, Isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, decyl and other alkyl groups, phenyl, tolyl, xylyl, naphthyl Aryl groups such as benzyl group, phenylethyl group, phenylpropyl group, etc., alkenyl groups such as vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, hexenyl group, cyclohexenyl group, octenyl group, etc. Some or all of the hydrogen atoms in these groups are substituted with halogen atoms such as fluorine, bromine and chlorine, cyano groups, etc. Which was, for example, chloromethyl group, chloropropyl group, bromoethyl group, trifluoropropyl group, cyanoethyl group and the like.

In this case, at least two of R ¹ must be alkenyl groups (preferably having 2 to 8 carbon atoms, more preferably 2 to 6). The content of alkenyl groups in R ¹ 0.001 to 20 mol%, it is particularly preferable to be 0.01 to 10 mol%. This alkenyl group may be bonded to a silicon atom at the end of the molecular chain, may be bonded to a silicon atom in the middle of the molecular chain, or may be bonded to both.

  The structure of the organopolysiloxane basically has a linear structure, but may be partially a branched structure, a cyclic structure, or the like. The molecular weight is not particularly limited, and can be used from a low-viscosity liquid to a high-viscosity raw rubber-like one. However, in order to cure to a rubber-like elastic body, the viscosity at 25 ° C. is 100 mPa · s or more. Usually, it is 100 to 1,000,000 mPa · s, and particularly preferably 500 to 100,000 mPa · s. In the present invention, the viscosity is a value at 25 ° C. measured by a rotational viscometer (BL type, BH type, BS type).

The organohydrogenpolysiloxane of the component (B) has at least 2 (usually 2 to 200), preferably 3 or more, more preferably 3 to 100 silicon-bonded hydrogen atoms in one molecule. What is shown by the following average composition formula (2) can be used.
R _b H _c SiO _{(4-bc) / 2} (2)
Wherein R is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, b is 0.7 to 2.1, and c is 0.001 to 1. 0.0 and b + c is 0.8 to 3.0, preferably b is 0.9 to 2.0, c is 0.01 to 1.0, and b + c is 1.0 to 2.7. Number.)

Here, the unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms represented by R, is the same as those exemplified as R ^{1 in} the above average composition formula (1). Although it can mention, the thing which does not have an aliphatic unsaturated group is preferable. The molecular structure of the organohydrogenpolysiloxane may be any of linear, cyclic, branched, three-dimensional network, etc. The number of silicon atoms in one molecule (or the degree of polymerization) is A liquid form is suitably used at room temperature (25 ° C.) of 2 to 300 pieces, particularly about 4 to 150 pieces. In addition, the hydrogen atom couple | bonded with a silicon atom may be located in any of the molecular chain terminal and the middle of a molecular chain, and may be located in both.

More specific examples of such an organohydrogenpolysiloxane include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, and tris (dimethylhydrogensiloxy) methylsilane. , Tris (dimethylhydrogensiloxy) phenylsilane, methylhydrogensiloxane cyclic polymer, methylhydrogensiloxane / dimethylsiloxane cyclic copolymer, trimethylsiloxy group-blocked methylhydrogenpolysiloxane, trimethylsiloxy group-blocked dimethyl at both ends Siloxane / methylhydrogensiloxane copolymer, dimethylpolysiloxane blocked with dimethylhydrogensiloxy at both ends, dimethylsiloxane / blocked with dimethylhydrogensiloxy at both ends Siloxane copolymers, both end trimethylsiloxy-blocked methylhydrogensiloxane-diphenylsiloxane copolymers, both end trimethylsiloxy-blocked methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymer, (CH _{3) 2} HSiO Copolymer composed of _1/2 unit and SiO _4/2 unit, Copolymer composed of (CH ₃ ) ₂ HSiO _1/2 unit, SiO _4/2 unit and (C ₆ H ₅ ) SiO _3/2 unit Examples include coalescence.

  The (B) component organohydrogenpolysiloxane has a viscosity at 25 ° C. of 1 to 1,000 mPa · s, usually 3 to 500 mPa · s, preferably 5 to 300 mPa · s. If the viscosity at 25 ° C. is less than 1 mPa · s, sufficient crosslinking may not be performed, and if it exceeds 1,000 mPa · s, the reactivity may be insufficient.

  The compounding amount of the organohydrogenpolysiloxane is preferably 0.1 to 50 parts by mass, and particularly preferably 0.3 to 30 parts by mass with respect to 100 parts by mass of the organopolysiloxane of the component (A). If the amount is less than 0.1 parts by mass, the crosslinking may not be sufficiently performed. If the amount exceeds 50 parts by mass, the physical properties of the rubber may be deteriorated.

  In addition, this organohydrogenpolysiloxane is similar to the alkenyl group bonded to the silicon atom in the component (A) for the same reason as the hydrogen atom bonded to the silicon atom in the component (B) (that is, Si—H group). The molar ratio may be 0.5 to 5 mol / mol, preferably 0.8 to 4 mol / mol, more preferably 1 to 3 mol / mol.

  The addition reaction catalyst for component (C) is a catalyst for promoting the hydrosilylation addition reaction between the alkenyl group in component (A) and the Si—H group in component (B). , Platinum black, platinous chloride, chloroplatinic acid, reaction product of chloroplatinic acid and monohydric alcohol, complex of chloroplatinic acid and olefins, platinum catalyst such as platinum bisacetoacetate, palladium catalyst, rhodium And platinum group metal catalysts such as system catalysts. In addition, although the compounding quantity of this addition reaction catalyst can be made into a catalytic amount, 0.5-1,000 ppm is preferable with respect to the total mass of (A) and (B) component as a platinum group metal normally, Especially. It is preferable to add 1 to 500 ppm.

  In addition to these components (A) to (C), (D) a polyether, a polyhydric alcohol or a derivative thereof can be further blended for the purpose of reducing compression set. Specific examples of the polyether include ring-opening polymers and ring-opening copolymers of alkylene oxides such as ethylene oxide and propylene oxide. Specific examples of the polyhydric alcohol or derivative thereof include glycerin, ethylene glycol, Polyhydric alcohols such as propylene glycol, pentaerythritol and glycerin-α-monochlorohydrin, oligomers such as dimers and trimers of polyhydric alcohols such as diethylene glycol, triethylene glycol and dipropylene glycol, polyethylene glycol, polypropylene Polymers of these polyhydric alcohols such as glycol and crown ether or copolymers of two or more, ethylene glycol monoethyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl And ethers, partially etherified products such as dipropylene glycol monoethyl ether, partially esterified products such as glycerin monoacetate, glycerin diacetate, and ethylene glycol monoacetate, and partially silylated products. A mixture of seeds or more can be used.

  When mix | blending the said (D) component, it is 1-30 mass parts with respect to 100 mass parts of (A) component, Preferably it is 3-20 mass parts. If the amount exceeds 30 parts by mass, the physical properties of the rubber will deteriorate significantly.

  The silicone rubber composition of the present invention may contain fumed silica, precipitated silica, fused silica, calcined silica, sol-gel spherical silica, crystalline silica (quartz powder), diatomaceous earth, etc. Fine particles, fillers such as calcium carbonate, silicone resin as a reinforcing agent, carbon black, conductive zinc white, conductive agents such as metal powder, nitrogen-containing compounds and acetylene compounds, phosphorus compounds, nitrile compounds, carboxylates, The present invention includes hydrosilylation reaction control agents such as tin compounds, mercury compounds and sulfur compounds, heat-resistant agents such as iron oxide and cerium oxide, internal mold release agents such as dimethylsilicone oil, adhesion-imparting agents, and thixotropic agents. It can mix | blend arbitrarily in the range which does not impair the effect of.

  The silicone rubber composition of the present invention can be prepared according to a conventional method by mixing the above-mentioned organic resin hollow filler, the components (A) to (D) and a predetermined amount of other components as required. . The viscosity of the composition is preferably 1 to 1,000 Pa · s, more preferably 2 to 500 Pa · s, and still more preferably about 5 to 200 Pa · s. If it is less than 1 Pa · s, rubber properties of the cured product may be insufficient, and if it exceeds 1,000 Pa · s, the hollow filler may be broken during molding.

  The method for curing the silicone rubber composition according to the present invention includes injection molding, compression molding, injection molding, coating, and the like, and the curing condition is preferably in the range of 10 seconds to 1 hour at a temperature of 100 to 300 ° C. Adopted. In addition, for the purpose of intentionally destroying the hollow filler made of organic resin, lowering the compression set, reducing the low molecular siloxane component, etc., after molding, further in an oven at 120 to 250 ° C. for 30 minutes to 70 hours. About post-curing (secondary curing) may be performed.

  The cured product of the silicone rubber composition of the present invention can be suitably used as a silicone rubber layer of a heat fixing roll in which a silicone rubber layer is provided on the outer peripheral surface of a roll shaft. Examples thereof include a heat fixing roll of a heat fixing device in an electrostatic recording apparatus such as an electrophotographic copying machine, a printer, and a facsimile machine.

  The heat fixing roll of the present invention forms a cured product layer of the silicone rubber composition on a core metal such as stainless steel, iron, nickel, and aluminum. In this case, the material, dimensions, etc. of the core metal are rolls. Depending on the type, it can be selected as appropriate. In addition, a method for molding and curing the silicone rubber composition can be appropriately selected. For example, the silicone rubber composition can be molded by a method such as injection molding, transfer molding, injection molding, or coating, and is cured by heating. A fluororesin layer or a fluororubber layer may be further provided on the outer periphery of the silicone rubber layer. In this case, the fluororesin layer is formed of a fluororesin coating material, a fluororesin tube, or the like, and covers the silicone rubber layer.

  Here, examples of the fluorine resin coating material include latex of polytetrafluoroethylene resin (PTFE), Daiel latex (made by Daikin Industries, Ltd., fluorine latex), and the like as a fluorine resin tube. May use commercially available products, such as polytetrafluoroethylene resin (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA), fluorinated ethylene-polypropylene copolymer resin (FEP), polyfluorinated. Examples thereof include vinylidene resin (PVDF) and polyvinyl fluoride resin, and among these, PFA is particularly preferable.

  In addition, although the thickness of the said silicone rubber layer is selected suitably, it is preferable that it is 0.05-80 mm, especially 0.1-50 mm at the point which utilizes the rubber elasticity of silicone rubber. The thickness of the fluororesin or fluororubber layer formed thereon is preferably 5 to 200 μm, particularly 10 to 100 μm.

  Furthermore, the thermal conductivity of the silicone rubber layer is preferably 0.15 W / m · ° C. or less, more preferably 0 in terms of storing heat without releasing the heat received from the heater, heater roll or belt. 0.05 to 0.14 W / m · ° C.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited to these. In addition, the part in each example shows a mass part, and the particle size distribution and average particle diameter of the hollow filler were obtained by a dry measurement method using a Microtrac particle size distribution measuring device (manufactured by Nikkiso Co., Ltd.). In addition, although the hollow filler in Example 3 and Comparative Example 3 is the same product, since the production lot is different, the particle size distribution is different.

[Example 1]
Side chain vinyl group-containing dimethylpolysiloxane (polymerization degree 700, vinyl value 0.0094 mol / 100 g), hydrophobized fumed silica having a specific surface area of 110 m ² / g (manufactured by Nippon Aerosil Co., Ltd., R -972) 2 parts, a specific gravity of 0.04, an average particle size of 50 μm, and a hollow filler made of a thermoplastic resin having a total particle size of 30 μm or less and 70 μm or more (acrylonitrile, methyl acrylate, methyl methacrylate) (Copolymer) 3.6 parts (corresponding to 38% by volume in the cured product) was put into a planetary mixer and stirred for 30 minutes, and further has Si-H groups at both ends and side chains as a crosslinking agent. 3.8 parts of methyl hydrogen polysiloxane A (polymerization degree 17, Si—H group amount 0.0030 mol / g), 5 parts of ethylene glycol, reaction control As a silicone rubber composition (1), 0.05 part of ethynylcyclohexanol was added and 0.1 part of platinum catalyst (Pt concentration: 1%) was mixed with the composition obtained by continuing stirring for 15 minutes. . This silicone rubber composition (1) was press-cured at 120 ° C. × 10 minutes, 130 ° C. × 10 minutes, and 140 ° C. × 10 minutes, followed by post-curing at 200 ° C. for 4 hours, and 2 mm and 6 mm After the appearance was checked, the specific gravity and hardness (durometer A) were measured from a 2 mm sheet according to JIS K6249, the thermal conductivity was further cut from the 6 mm sheet, and further cut into 10 mm squares, and compression set (180 ° C. × 22 hours, 25% compression) was measured. The results are shown in Table 1.

[Example 2]
50 parts of side chain vinyl group-containing dimethylpolysiloxane (polymerization degree 700, vinyl value 0.0094 mol / 100 g), 50 parts of dimethylpolysiloxane (polymerization degree 500) blocked at both ends with dimethylvinylsiloxy groups, specific surface area 110 m ² parts / g hydrophobized fumed silica (produced by Nippon Aerosil Co., Ltd., R-972) 5 parts, specific gravity 0.02, average particle size 90 μm, specific gravity 0.04, average particle size 50 μm were mixed. 4 parts (45% by volume in the cured product) of thermoplastic resin hollow filler (acrylonitrile, acrylate copolymer) having an average particle diameter of 72 μm and a total of particle diameters of 100 μm or more and 40 μm or less being 38% by mass. In a planetary mixer and stirring was continued for 30 minutes, and then the methyl hydrogen policy of Example 1 was further used as a crosslinking agent. 3.5 parts of Loxane A, 3 parts of triethylene glycol, 0.05 parts of ethynylcyclohexanol as a reaction control agent were added, and the platinum catalyst (Pt concentration 1%) 0 was added to the resulting composition after stirring for 15 minutes. 1 part was mixed and this was made into the silicone rubber composition (2). This silicone rubber composition (2) was press-cured at each temperature in the same manner as in Example 1, and the specific gravity, hardness (durometer A), thermal conductivity, and compression set were measured. The results are shown in Table 1.

[Example 3]
50 parts of side chain vinyl group-containing dimethylpolysiloxane (polymerization degree 700, vinyl value 0.0094 mol / 100 g), 50 parts of dimethylpolysiloxane (polymerization degree 500) blocked at both ends with dimethylvinylsiloxy groups, specific surface area 200 m ² parts per gram of fumed silica (Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.), specific gravity 0.03, average particle size of 105 μm, and the total of particle sizes of 140 μm or more and 70 μm or less is 24% by mass Hollow filler made of plastic resin (Matsumoto Yushi Seiyaku Co., Ltd., Microsphere F80ED Lot A) 3 parts (corresponding to 36% by volume in the cured product), specific gravity 0.35, average particle size 56 μm glass hollow filler ( Tokai Kogyo Co., Ltd., Cellstar Z-36) 15 parts was put into a planetary mixer and stirred for 30 minutes. As a composition obtained by adding 3.5 parts of methylhydrogenpolysiloxane A of Example 1, 6 parts of diethylene glycol monomethyl ether, 0.05 part of ethynylcyclohexanol as a reaction control agent, and continuing stirring for 15 minutes. Platinum catalyst (Pt concentration 1%) 0.1 part was mixed and this was made into the silicone rubber composition (3). This silicone rubber composition (3) was press-cured at each temperature in the same manner as in Example 1, and the specific gravity, hardness (durometer A), thermal conductivity, and compression set were measured. The results are shown in Table 1.

[Comparative Example 1]
Side chain vinyl group-containing dimethylpolysiloxane (polymerization degree 700, vinyl value 0.0094 mol / 100 g), hydrophobized fumed silica having a specific surface area of 110 m ² / g (manufactured by Nippon Aerosil Co., Ltd., R -972) 2 parts, specific gravity 0.04, average particle diameter 50 μm, thermoplastic resin hollow filler (total of acrylonitrile, methyl acrylate, methyl methacrylate, 18% total of particle diameter 40 μm or less and particle diameter 65 μm or more) (Copolymer) 4 parts (corresponding to 45% by volume in the cured product) was put in a planetary mixer and stirred for 30 minutes. Then, 3.8 of methylhydrogenpolysiloxane A of Example 1 was further used as a crosslinking agent. 5 parts ethylene glycol, 0.05 parts ethynylcyclohexanol as a reaction control agent, and continued stirring for 15 minutes Therefore a platinum catalyst (Pt concentration 1%) in the composition were mixed with 0.1 parts of which was used as a silicone rubber composition (4). This silicone rubber composition (4) was press-cured at each temperature in the same manner as in Example 1, and the specific gravity, hardness (durometer A), thermal conductivity, and compression set were measured. The results are shown in Table 1.

[Comparative Example 2]
50 parts of side chain vinyl group-containing dimethylpolysiloxane (polymerization degree 700, vinyl value 0.0094 mol / 100 g), 50 parts of dimethylpolysiloxane (polymerization degree 500) blocked at both ends with dimethylvinylsiloxy groups, specific surface area 110 m ² parts / g hydrophobized fumed silica (manufactured by Nippon Aerosil Co., Ltd., R-972), specific gravity 0.03, average particle size 75 μm, particle size 95 μm or more and 55 μm or less is 16 in total. 4 parts by mass of thermoplastic resin hollow filler (acrylonitrile / acrylic acid ester copolymer) (corresponding to 45% by volume in the cured product) is put into a planetary mixer and stirred for 30 minutes. As a crosslinking agent, 3.5 parts of methyl hydrogen polysiloxane A of Example 1, 3 parts of triethylene glycol, a reaction control agent, Then, 0.05 part of ethynylcyclohexanol was added and 0.1 part of platinum catalyst (Pt concentration 1%) was mixed with the composition obtained by continuing stirring for 15 minutes to obtain a silicone rubber composition (5). . This silicone rubber composition (5) was press-cured at each temperature in the same manner as in Example 1, and the specific gravity, hardness (durometer A), thermal conductivity, and compression set were measured. The results are shown in Table 1.

[Comparative Example 3]
50 parts of side chain vinyl group-containing dimethylpolysiloxane (polymerization degree 700, vinyl value 0.0094 mol / 100 g), 50 parts of dimethylpolysiloxane (polymerization degree 500) blocked at both ends with dimethylvinylsiloxy groups, specific surface area 200 m ² parts / g of fumed silica (Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.), specific gravity 0.03, average particle size 102 μm, total particle size 130 μm or more and 75 μm or less is 18% by mass Hollow filler made of plastic resin (Matsumoto Yushi Seiyaku Co., Ltd., Microsphere F80ED Lot B) 3 parts (corresponding to 36% by volume in the cured product), specific gravity 0.35, average particle size 56 μm glass hollow filler (Tokai Kogyo Co., Ltd., Cellstar Z-36) 15 parts was put into a planetary mixer and stirred for 30 minutes. A composition obtained by adding 3.5 parts of methyl hydrogen polysiloxane A of Example 1 as an agent, 6 parts of diethylene glycol monomethyl ether and 0.05 part of ethynylcyclohexanol as a reaction control agent, and continuing stirring for 15 minutes. Was mixed with 0.1 part of a platinum catalyst (Pt concentration 1%) to obtain a silicone rubber composition (6). This silicone rubber composition (6) was press-cured at each temperature in the same manner as in Example 1, and the specific gravity, hardness (durometer A), thermal conductivity, and compression set were measured. The results are shown in Table 1.

[Example 4]
Primer No. for addition reaction type liquid silicone rubber on the surface of an aluminum shaft having a diameter of 24 mm and a length of 300 mm. 101 A / B (manufactured by Shin-Etsu Chemical Co., Ltd.) was applied. The silicone rubber composition (1) of Example 1 was filled between a 50 μm-thick fluorine PFA tube whose inner surface was primed and an aluminum shaft, and was cured by heating at 120 ° C. for 30 minutes, and further at 200 ° C. for 4 hours. A PFA resin-coated silicone rubber roll having an outer diameter of 30 mm and a length of 250 mm was prepared.

  When this roll was incorporated as a fixing roll of a PPC copying machine and allowed to stand for 3 days in a pressurized state at 80 ° C., paper was passed through, but bleeding occurred due to poor fixing up to the third sheet, but there was no problem thereafter.

[Comparative Example 4]
Primer No. for addition reaction type liquid silicone rubber on the surface of an aluminum shaft having a diameter of 24 mm and a length of 300 mm. 101 A / B (manufactured by Shin-Etsu Chemical Co., Ltd.) was applied. The silicone rubber composition (4) of Comparative Example 1 was filled between a 50 μm-thick fluorine PFA tube whose inner surface was primed and an aluminum shaft, cured by heating at 120 ° C. for 30 minutes, and further post-treated at 200 ° C. for 4 hours. A PFA resin-coated silicone rubber roll having an outer diameter of 30 mm and a length of 250 mm was prepared.

  When this roll was incorporated as a fixing roll of a PPC copying machine and allowed to stand in a pressurized state at 80 ° C. for 3 days and then passed through, bleeding occurred due to poor fixing up to the 25th sheet.

[Example 5]
Primer No. for addition reaction type liquid silicone rubber on the surface of an aluminum shaft having a diameter of 24 mm and a length of 300 mm. 101 A / B (manufactured by Shin-Etsu Chemical Co., Ltd.) was applied. Further, the silicone rubber composition (2) of Example 2 was applied thereon, cured by heating at 130 ° C. for 30 minutes, and further post-cured at 180 ° C. for 2 hours to obtain a silicone rubber roll having a rubber thickness of 2 mm. Dairy latex and silicone rubber primer GLP-103SR (Daikin Kogyo Co., Ltd.) are evenly applied to the surface of the cured product, heated at 80 ° C. for 10 minutes, and further, Daiel latex GLS-213 is sprayed uniformly. Apply to the surface of this cured product with Daiel latex and silicone rubber primer GLP-103SR (manufactured by Daikin Industries, Ltd.), heat at 80 ° C. for 10 minutes, and further, Daiel Latex GLS-213. Was spray-applied uniformly and baked at 300 ° C. for 1 hour to prepare a Daiel latex-coated silicone rubber roll having an outer diameter of 28 mm × length of 250 mm.

  When this roll was incorporated as a fixing roll of a PPC copying machine and allowed to stand in a pressurized state at 80 ° C. for 3 days and then passed through, bleeding occurred due to poor fixing up to the fifth sheet, but there was no problem thereafter.

[Comparative Example 5]
Primer No. for addition reaction type liquid silicone rubber on the surface of an aluminum shaft having a diameter of 24 mm and a length of 300 mm. 101 A / B (manufactured by Shin-Etsu Chemical Co., Ltd.) was applied. Furthermore, the silicone rubber composition (5) of Comparative Example 2 was applied thereon, heat-cured at 130 ° C. for 30 minutes, and further post-cured at 180 ° C. for 2 hours to obtain a silicone rubber roll having a rubber thickness of 2 mm. Dairy latex and silicone rubber primer GLP-103SR (Daikin Kogyo Co., Ltd.) are evenly applied to the surface of the cured product, heated at 80 ° C. for 10 minutes, and further, Daiel latex GLS-213 is sprayed uniformly. Apply to the surface of this cured product with Daiel latex and silicone rubber primer GLP-103SR (manufactured by Daikin Industries, Ltd.), heat at 80 ° C. for 10 minutes, and further, Daiel Latex GLS-213. Was spray-coated and heated and fired at 300 ° C. for 1 hour to produce a Daiel latex-coated silicone rubber roll having an outer diameter of 28 mm × length of 250 mm. Several holes were observed on the surface.

  When this roll was incorporated as a fixing roll for a PPC copying machine and allowed to stand for 3 days in a pressurized state at 80 ° C., paper was passed through. Bleeding occurred due to poor fixing and did not recover even after 100 sheets were passed. It was.

Claims (8)

A method for reducing the compression set of the low heat conductive silicone rubber in a heat fixing roll in which a low heat conductive silicone rubber layer is formed on a core metal, which bonds to at least two silicon atoms in one molecule. Particles having an average particle diameter of 5 to 200 μm and 30% or more smaller than the average particle diameter in 100 parts by mass of an organopolysiloxane containing an alkenyl group and a curing effective amount of a curing agent for curing the organopolysiloxane A silicone rubber composition containing 0.3 to 100 parts by mass of a hollow filler made of an organic resin having a wide particle size distribution with a total particle size of 20 to 70% by mass and a particle size larger than 30% by mass. A method for improving the compression set resistance of a low heat conductive silicone rubber for a heat fixing roll, characterized in that a low heat conductive silicone rubber is obtained.   Further, a silicone rubber composition containing 1 to 30 parts by mass of polyether, polyhydric alcohol or derivative thereof with respect to 100 parts by mass of organopolysiloxane containing an alkenyl group bonded to at least two silicon atoms in one molecule. The method according to claim 1, wherein The method according to claim 1 or 2, wherein the true specific gravity of the hollow filler is 0.01 to 1.0 .   The hollow filler is formed of a polymer of a monomer selected from vinylidene chloride, acrylonitrile, methacrylonitrile, acrylic acid ester and methacrylic acid ester, or a copolymer of two or more of the above monomers. Or the method of 3. The method according to any one of claims 1 to 4, wherein the thermal conductivity after curing is 0.05 to 0.15 W / m · ° C.   The method according to any one of claims 1 to 5, which comprises curing by any one of injection molding, compression molding, injection molding and coating.   The method according to any one of claims 1 to 6, comprising curing at 100 to 300 ° C for 10 seconds to 1 hour.   The method according to any one of claims 1 to 7, further comprising post-curing at 120 to 250 ° C for 30 minutes to 70 hours after molding.