JP2018124544A - Additive curable liquid silicone rubber mixture, member for electrophotography and manufacturing method thereof, and fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic member provided with an elastic layer in which graphite particles are dispersed in silicone rubber and have high thermal conductivity in the thickness direction. An electrophotographic member has a substrate and an elastic layer on the substrate, and the elastic layer contains a cured product of an addition-curable liquid silicone rubber mixture containing graphite particles, and the graphite particles. The amount of dibutylphthalate (DBP) oil absorbed is 80 cm3 / 100 g or more and 150 cm3 / 100 g or less, and the thermal conductivity in the thickness direction of the elastic layer is 1.1 W / (m · K) or more and 5.0 W / (m ·). K) or less, and the tensile elastic modulus of the elastic layer is 0.1 MPa or more and 4.0 MPa or less. [Selection diagram] Fig. 2

Description

  The present invention relates to an electrophotographic member used in a fixing device of an electrophotographic apparatus such as a copying machine or a printer, a manufacturing method thereof, and a fixing device. The present invention also relates to an addition-curable liquid silicone rubber mixture used for the electrophotographic member.

  An electrophotographic apparatus includes a heating member and a pressing member disposed to face the heating member in order to fix an unfixed toner image formed on the recording medium to the recording medium. (Thermal fixing device) is used.

  Usually, in a fixing device used in an electrophotographic system, a rotating body as a pair of electrophotographic members such as a roller and a roller, a film and a roller, a belt and a belt, and a belt and a roller is arranged so as to be able to press the recording medium. Yes. Then, a recording medium such as paper holding an image of unfixed toner is introduced into the press contact portion formed between the rotating bodies and heated to melt the toner and fix the image on the recording medium.

  Here, a member that is in contact with the unfixed toner image held on the recording medium and that heats the unfixed toner is disposed facing the heating member and the heating member, and a member that forms a fixing nip together with the heating member is added. It is called a pressure member. The heating member includes a fixing roller, a fixing film, and a fixing belt depending on the form. Some electrophotographic members used as heating members have an elastic layer containing silicone rubber (see Patent Document 1). In such an electrophotographic member, it is preferable to increase the thermal conductivity of the elastic layer.

Japanese Patent No. 5471350

  The present inventors have studied various heat conductive fillers in order to increase the thermal conductivity of an elastic layer containing a cured product of an addition curable liquid silicone rubber mixture. As a result, it has been found that graphite can improve the thermal conductivity of the elastic layer more efficiently than a thermally conductive filler such as alumina. That is, graphite can impart high thermal conductivity to the elastic layer even when the content is relatively small compared to alumina. However, an addition-curable liquid silicone rubber mixture obtained by blending graphite in an addition-curable liquid silicone rubber may be difficult to sufficiently cure. When graphite is used to improve the thermal conductivity of an elastic layer containing a cured product of addition-curable liquid silicone rubber, it is necessary to develop technology to stably cure the addition-curable liquid silicone rubber. The inventors have recognized.

  One embodiment of the present invention is an elastic layer in which graphite (graphite particles) is dispersed in silicone rubber, and includes an elastic layer having a high thermal conductivity in the thickness direction, and a method for producing the same It is aimed at.

  Another aspect of the present invention is directed to providing an addition-curable liquid silicone rubber mixture having sufficient curability.

  Still another aspect of the present invention is directed to providing a fixing device that contributes to the formation of a high-quality electrophotographic image.

According to one aspect of the present invention, an electrophotographic member having a substrate and an elastic layer on the substrate, the elastic layer including a cured product of an addition-curable liquid silicone rubber mixture containing graphite particles. , DBP (dibutyl phthalate) oil absorption amount of the graphite ^particles, and at 80 cm 3/100 g or more 150 cm ^3/100 g or less, the thermal conductivity in the thickness direction of the elastic layer, 1.1W / (m · K) or more 5 There is provided an electrophotographic member having a tensile modulus of elasticity of 0.1 MPa or more and 4.0 MPa or less of 0.0 W / (m · K) or less.

According to another aspect of the present invention, an organopolysiloxane having an unsaturated aliphatic group, an organopolysiloxane having an active hydrogen bonded to silicon, a catalyst, and graphite particles, and DBP oil absorption of the graphite particles ^amounts, and at 80 cm 3/100 g or more 150 cm ^3/100 g or less, and a weight average molecular weight of organopolysiloxane having active hydrogen bonded to the silicon, it is 5500 or more 65000 or less addition curable liquid silicone rubber mixtures Provided.

  According to another aspect of the present invention, there is provided a method for producing an electrophotographic member comprising a substrate and an elastic layer on the substrate, the coating film of the addition-curable liquid silicone rubber mixture on the substrate. There is provided a method for producing an electrophotographic member comprising a step of curing to form the elastic layer.

  According to still another aspect of the present invention, there is provided a fixing device having a heating member and a pressure member disposed to face the heating member, wherein the heating member is the electrophotographic member. An apparatus is provided.

  According to one aspect of the present invention, an electrophotographic member having an elastic layer in which graphite (graphite particles) is dispersed in silicone rubber and having an elastic layer having a high thermal conductivity in the thickness direction can be obtained. it can. According to another aspect of the present invention, an addition-curable liquid silicone rubber mixture having sufficient curability can be obtained.

  According to still another aspect of the present invention, a fixing device capable of forming a high-quality electrophotographic image can be obtained.

(A) is a cross-sectional view of an electrophotographic member having an endless belt shape according to one aspect of the present invention, and (B) is an electrophotographic member having a roller shape according to one aspect of the present invention. It is sectional drawing. It is sectional drawing of the elastic layer of the member for electrophotography which concerns on 1 aspect of this invention. It is a schematic diagram of an example for demonstrating the process of laminating | stacking a fluororesin surface layer. FIG. 11 is an explanatory diagram of a fixing device according to an aspect of the present invention.

  The present inventors examined the reason why the addition-curable liquid silicone rubber mixture containing graphite particles may not be sufficiently cured. In the examination process, it was confirmed that the larger the DBP (dibutyl phthalate) oil absorption of the graphite particles used, the more markedly the inhibition of curing of the addition curable liquid silicone rubber mixture. From these experimental results, the present inventors considered that the inhibition of curing of the addition-curable liquid silicone rubber mixture was caused by the following reason. That is, an organopolysiloxane having an active hydrogen bonded to a silicon atom that functions as a crosslinking agent is absorbed into the pores of the graphite particles, and the hydrosilylation reaction does not proceed sufficiently, so that the curing is inhibited. Was considered. Therefore, the present inventors considered that the cross-linking agent becomes difficult to be absorbed in the pores of the graphite particles by increasing the molecular weight of the cross-linking agent. As a result, by increasing the molecular weight of the cross-linking agent, it was found that even an addition-curable liquid silicone rubber mixture containing graphite particles having a large DBP oil absorption can be sufficiently cured, leading to the present invention. .

  Japanese Patent Laid-Open No. 8-113713 discloses an invention relating to a conductive silicone rubber composition containing a carbon-based conductivity imparting agent such as carbon black or graphite. And the conductive silicone rubber composition which mix | blended carbon-type electroconductivity imparting agent with silicone rubber in large quantities describes that sclerosis | hardenability falls. However, the carbon-based conductivity imparting agent specifically used in the examples and comparative examples of Japanese Patent Publication No. 8-113713 is only carbon black, and there is no specific disclosure or suggestion about graphite. Absent.

In the addition-curable liquid silicone rubber mixture according to one embodiment of the present invention, the weight average molecular weight of the organopolysiloxane having active hydrogen bonded to a silicon atom, which is a crosslinking agent for the addition-curable liquid silicone rubber, is 5500 to 65000. . Thus, addition curing type liquid silicone rubber mixture, for example, DBP oil absorption amount, also contain graphite particles having a high value such as 80~150cm 3 ^/ 100g, absorption of cross-linking agents according to the graphite particles is suppressed . As a result, the inhibition of curing of the addition-curable liquid silicone rubber mixture can be made difficult to occur. Moreover, especially the graphite particle with a high DBP oil absorption can raise the thermal conductivity of silicone rubber efficiently. Therefore, the addition-curable liquid silicone rubber mixture according to one embodiment of the present invention can provide a silicone rubber with further improved thermal conductivity. Moreover, the member for electrophotography provided with the elastic layer which further improved thermal conductivity can be given.

  Hereinafter, the present invention will be described in detail.

(1) Configuration of Electrophotographic Member An electrophotographic member according to one embodiment of the present invention will be described with reference to the drawings.

  FIG. 1A and FIG. 1B are schematic cross-sectional schematic views of an electrophotographic member according to this embodiment. FIG. 1A shows an example of an endless belt-shaped electrophotographic member (hereinafter also referred to as “electrophotographic belt”). FIG. 1B shows an example of a roller-shaped electrophotographic member (hereinafter also referred to as “electrophotographic roller”).

  The electrophotographic belt shown in FIG. 1A has an endless belt-shaped substrate (substrate) 1 and an elastic layer 2 covering the outer peripheral surface of the substrate 1. Further, the electrophotographic roller shown in FIG. 1B has a cylindrical or columnar substrate 1 and an elastic layer 2 covering the outer peripheral surface of the substrate. Further, a surface layer (release layer) 4 may be provided on the outer peripheral surface of the elastic layer 2. Further, an adhesive layer 3 may be provided between the elastic layer 2 and the surface layer 4. FIG. 2 is a schematic view of a circumferential section of the elastic layer of the electrophotographic member according to FIGS. 1A and 1B, that is, a section in a direction orthogonal to the longitudinal direction of the electrophotographic member. . The elastic layer includes a cured product of an addition-curable liquid silicone rubber mixture, and the cured product is a cured silicone rubber (cured product of addition-curable liquid silicone rubber 2a) as a matrix and graphite dispersed in the matrix. Particle 2b.

(2) Elastic layer The elastic layer is formed by curing an addition-curable liquid silicone rubber mixture (addition-curable liquid silicone rubber composition) containing at least graphite particles and an addition-curable liquid silicone rubber (component). Can do. That is, the elastic layer can be a cured product (solidified product) of an addition curable liquid silicone rubber mixture, and can include at least a cured product 2a of the addition curable liquid silicone rubber and graphite particles 2b. .

  The addition-curable liquid silicone rubber can contain an organopolysiloxane having an unsaturated aliphatic group, an organopolysiloxane having active hydrogen bonded to silicon as a crosslinking agent, and a catalyst (for example, a platinum compound).

  Electrophotographic members (such as a fixing roller, a fixing film, and a fixing belt) can be used as one or both of a heating member and a pressure member. When an electrophotographic member is used as a heating member, the elastic layer functions as a layer that imparts elasticity to follow the unevenness of the paper during fixing. When an electrophotographic member is used as a pressure member, the elastic layer functions as a layer that imparts elasticity to ensure a nip width during fixing. In order to express these functions, it is desirable to use uncured silicone rubber as a base material for forming the elastic layer. The uncured silicone rubber mainly includes addition curable liquid silicone rubber and millable silicone rubber, but in the present invention, addition curable liquid silicone rubber is used from the viewpoint of easy dispersion of graphite particles and filler.

  Below, the addition-curable liquid silicone rubber mixture used for producing the elastic layer will be described.

(2-1) Addition-curable liquid silicone rubber mixture The addition-curable liquid silicone rubber mixture contains an addition-curable liquid silicone rubber and graphite particles. The addition curable liquid silicone rubber mixture may further contain a filler to be described later.
Subsequently, each component contained in the addition-curable liquid silicone rubber mixture will be described in detail.

(2-1-1) Addition-curable liquid silicone rubber As described above, the addition-curable liquid silicone rubber comprises (a) an organopolysiloxane having an unsaturated aliphatic group, (b) active hydrogen bonded to silicon. And (c) a platinum compound as a hydrosilylation (addition curing) catalyst. In the addition-curable liquid silicone rubber mixture, the content of these addition-curable liquid silicone rubber components (including platinum compounds) is preferably 50% by volume or more from the viewpoint of imparting elasticity to the electrophotographic member. Is more preferably 70% by volume or more.

Component (a): an organopolysiloxane having an unsaturated aliphatic group An organopolysiloxane having an unsaturated aliphatic group (hereinafter sometimes referred to as “component (a)”) is an unsaturated aliphatic such as a vinyl group. Any organopolysiloxane having a group can be used. For example, those shown in the following structural formulas 1 to 3 can be used as the component (a).

Either one or both intermediate units selected from the group consisting of an intermediate unit represented by R ₁ R ₁ SiO and an intermediate unit represented by R ₁ R ₂ SiO, and R ₁ R ₁ R ₂ SiO _1/2 A linear organopolysiloxane having molecular ends represented (see Structural Formula 1 below).

In Structural Formula 1, each R ₁ independently represents a monovalent unsubstituted or substituted hydrocarbon group that does not contain an unsaturated aliphatic group, each R ₂ independently represents an unsaturated aliphatic group, and m and n are Each independently represents an integer of 0 or more, provided that m + n represents an integer of 1 or more.

One or both of intermediate units selected from an intermediate unit represented by R ₃ SiO _3/2 and an intermediate unit represented by SiO _4/2 , and represented by R ₃ R ₃ R ₄ SiO _1/2 Branched organopolysiloxane having molecular ends (see Structural Formula 2 below).

In Structural Formula 2, each R ₃ independently represents a monovalent unsubstituted or substituted hydrocarbon group that does not contain an unsaturated aliphatic group, each R ₄ independently represents an unsaturated aliphatic group, and Y represents an organopolyethylene. Represents siloxane, p and q each independently represents an integer of 0 or more, provided that p + q represents an integer of 1 or more.

- has a molecular end represented by _{R 5 R 5 R 5 SiO 1/2} , and an intermediate unit represented by R ₅ R 6 SiO, and an intermediate unit represented by _R 5 _R 5 SiO optionally Linear organopolysiloxane (see Structural Formula 3 below).

In Structural Formula 3, each R ₅ independently represents a monovalent unsubstituted or substituted hydrocarbon group that does not contain an unsaturated aliphatic group, each R ₆ independently represents an unsaturated aliphatic group, and r is 0 or more. S represents an integer of 3 or more.

In the structural formulas 1 to 3, as the monovalent unsubstituted or substituted hydrocarbon group not containing an unsaturated aliphatic group bonded to a silicon atom and represented by R ₁ , R ₃ and R ₅ , respectively, For example, the following can be mentioned.

-Unsubstituted hydrocarbon group Alkyl group (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, etc.); aryl group (for example, phenyl group, etc.).

-Substituted hydrocarbon group For example, chloromethyl group, 3-chloropropyl group, 3,3,3-trifluoropropyl group, 3-cyanopropyl group, 3-methoxypropyl group and the like.

Here, all of R ₁ , R ₃ and R ₅ are preferably methyl groups because they are easy to synthesize and handle and easy to produce. That is, as the component (a), an organopolysiloxane in which a methyl group is bonded to a silicon atom constituting the main chain is preferably used.

In addition, as the unsaturated aliphatic group bonded to the silicon atom represented by R ₂ , R ₄ and R ₆ in the structural formulas 1 to 3, vinyl group, allyl group, 3-butenyl group, 4-pentenyl Group, 5-hexenyl group and the like can be exemplified. Here, R ₂ , R _4, and R ₆ are all preferably vinyl groups because they are easy to synthesize and handle, are inexpensive, and can easily undergo a crosslinking reaction.

  Here, in the structural formula 2, as the organopolysiloxane represented by Y, other branched organopolysiloxanes represented by the structural formula 2 can be exemplified. In this case, the branched organopolysiloxane represented by Structural Formula 2 can have a structure in which a plurality of similar branched organopolysiloxanes represented by Structural Formula 2 are bonded via an oxygen atom (siloxane bond).

  As a specific example of the component (a) which is preferably used, a methyl group is directly bonded to a silicon atom constituting a siloxane bond of the main chain, and an unsaturated aliphatic group is introduced into the side chain or the end of the molecule. Mention may be made of organopolysiloxanes having a structure. More specifically, for example, organopolysiloxanes represented by the following structural formula 4 and structural formula 5 can be given. Among these, an organopolysiloxane having an unsaturated aliphatic group at the molecular end represented by Structural Formula 5 is more preferable because it can be easily synthesized and is inexpensive.

In Structural Formula 4, each R ₆ independently represents an unsaturated aliphatic group, r represents an integer of 0 or more, and s represents an integer of 3 or more.

In Structural Formula 5, each R ₂ independently represents an unsaturated aliphatic group, and m represents a positive integer.

  (A) A component may be used individually by 1 type and may use 2 or more types together. For example, as the component (a), an organopolysiloxane represented by the above structural formula 4 and an organopolysiloxane represented by the above structural formula 5 may be blended.

From the viewpoint of facilitating the moldability of the addition-curable liquid silicone rubber mixture, the weight average molecular weight of the component (a) is preferably 20000 to 80000, and the kinematic viscosity at a temperature of 25 ° C. is, for example, 1000-30000 mm < ² > / sec is preferable.

  In addition, the weight average molecular weight of (a) component can be measured as a weight average molecular weight of polystyrene conversion by gel permeation chromatography (GPC).

Here, the weight average molecular weight of (a) component can be measured on condition of the following using the measuring method of molecular weight distribution by GPC.
The column is stabilized in a heat chamber at a temperature of 40 ° C., and toluene is passed through the column at this temperature as a solvent at a flow rate of 1 mL per minute. 100 μL of the toluene sample solution of the component (a) prepared to 0.3% by mass as the sample concentration (concentration of the component (a)) is injected into the column, and the molecular weight of the sample is measured. In measuring the molecular weight of a sample, the molecular weight distribution of the sample is expressed by logarithmic values of a calibration curve prepared by using several monodisperse polystyrene standard samples (trade names: TSKgel standard polystyrenes “0005202” to “0005211”, manufactured by Tosoh Corporation). Calculated from the relationship with retention time. Further, a GPC gel permeation chromatograph analyzer (trade name: HLC8220, manufactured by Tosoh Corporation) is used as the GPC apparatus, and a differential refractive index detector (trade name: RI-8020, manufactured by Tosoh Corporation) is used as the detector. . As the column, three commercially available polystyrene gel columns (trade name: Shodex GPC LF-804, manufactured by Showa Denko KK) are used in combination.

The kinematic viscosity η (mm ² / sec) of the organopolysiloxane having an unsaturated aliphatic group is, for example, a viscosity (viscosity) measured by a rotary viscometer (trade name: RV1, manufactured by Eiko Seiki Co., Ltd.). It can be calculated from the following calculation formula 1 using μ (mPa · s).

Formula 1
η = μ / ρ
Here, ρ is density, and in the case of organopolysiloxane, it is 0.97 g / cm ³ under normal temperature and normal pressure (for example, temperature 25 ° C., pressure 1013 hPa).

  As the addition-curable liquid silicone rubber, the amount of the unsaturated aliphatic group in the component (a) is 0.1 mol% or more and 2.0 mol% with respect to 1 mol of the silicon atom in the component (a). The following are preferred. More preferably, they are 0.2 mol% or more and 1.0 mol% or less with respect to 1 mol of silicon atoms.

Component (b): organopolysiloxane having active hydrogen bonded to silicon (crosslinking agent)
Organopolysiloxane having active hydrogen bonded to silicon (hereinafter sometimes referred to as component (b)) is produced by a hydrosilylation reaction with an unsaturated aliphatic group in component (a) due to the catalytic action of the platinum compound. It functions as a crosslinking agent for forming a crosslinked structure.

  As the component (b), any organopolysiloxane having a Si—H bond can be used. For example, a component satisfying the following conditions can be suitably used. In addition, (b) component may be used individually by 1 type, and may use 2 or more types (mixture) together.

-From the viewpoint of forming a crosslinked structure by reaction with an organopolysiloxane having an unsaturated aliphatic group, the average number of hydrogen atoms bonded to silicon atoms is 3 or more per molecule.
The organic group bonded to the silicon atom is, for example, a monovalent unsubstituted or substituted hydrocarbon group as described above. The organic group is preferably a methyl group because it is easy to synthesize and handle.
The siloxane skeleton (—Si—O—Si—) may be linear, branched or cyclic, but is preferably a linear one because it is easy to synthesize.
The Si—H bond may be present in any siloxane unit in the molecule.

  Specific examples of the component (b) include a linear organopolysiloxane represented by the following structural formula 6 and a cyclic crosslinking agent silicone polymer represented by the following structural formula 7.

In Structural Formula 6, each R ₇ independently represents a monovalent unsubstituted or substituted hydrocarbon group not containing an unsaturated aliphatic group, t represents an integer of 0 or more, and u represents an integer of 3 or more.

In Structural Formula 7, each R ₈ independently represents a monovalent unsubstituted or substituted hydrocarbon group not containing an unsaturated aliphatic group, v represents an integer of 0 or more, and w represents an integer of 3 or more.

R ₇ and R ₈ can both be a monovalent unsubstituted or substituted hydrocarbon group bonded to a silicon atom and containing no unsaturated aliphatic group, as described in structural formulas 1 to 3. Among others, easy to synthesize and handling, since the excellent heat resistance can be obtained, in R ₈ in R ₇ and structural formula 7 in the structural formula 6 is preferably 50% or more, respectively are methyl groups, More preferably, all R ₇ and R ₈ are methyl groups.

  In the addition-curable liquid silicone rubber mixture according to one embodiment of the present invention, the weight average molecular weight of the component (b) is 5500 or more and 65000 or less. When the weight average molecular weight of the component (b) is smaller than 5500, the component (b) is easily absorbed by the graphite particles, and it becomes difficult to sufficiently suppress the inhibition of curing of the addition-curable liquid silicone rubber mixture. On the other hand, when the weight average molecular weight of the component (b) is larger than 65,000, the kinematic viscosity of the addition-curable liquid silicone rubber mixture becomes too large, and the moldability may deteriorate. The weight average molecular weight of the component (b) is more preferably 6000 or more and 60000 or less.

In addition, the weight average molecular weight of (b) component can be measured by the same method as the above-mentioned weight average molecular weight of (a) component.
In addition, the kinematic viscosity of component (b) at a temperature of 25 ° C. is preferably, for example, 130 mm ² / sec or more and 9000 mm ² / sec or less.

In order to calculate the kinematic viscosity, the viscosity μ in the calculation formula 1 is measured. Specific examples of the measurement method include the following measurement methods. That is, first, a sample (for example, an addition-curable liquid silicone rubber mixture) whose viscosity is to be measured is applied to the sample table of the rotary viscometer described above, and a gap between the sample table and the sample table is formed using a rotating plate. The sample is sandwiched between layers of 105 μm. The plate is then rotated to shear the sample. The conditions of shear rate, the shear rate from ^{0 s -1} to ^{20s -1} is increased by 0.2 s ^-1 rate per second, then, 0.2 s ^-1 per second from ^{20s -1} to ^{0 s -1} Decrease by rate. The maximum value of the viscosity values measured in this process is set as the representative value, which is the viscosity μ in the calculation formula 1.

  As the addition-curable liquid silicone rubber, the amount of active hydrogen groups bonded to silicon in the organopolysiloxane (b) component is 1 mol% or more relative to 1 mol of silicon atoms in the component (b), What is 10 mol% or less is preferable.

(C) Catalyst As the hydrosilylation (addition curing) catalyst, for example, a platinum compound can be used. As this platinum compound, the following can be used, for example. That is, platinum carbonylcyclovinylmethylsiloxane complex vinylmethylcyclosiloxane, platinum divinyltetramethyldisiloxane complex, and the like.

(2-1-2) Graphite Particles As graphite (graphite) particles, both artificial graphite particles and natural graphite particles can be used. As natural graphite particles, those produced by pulverizing graphite produced from nature can be used. Artificial graphite is obtained by pulverizing coke as a raw material, forming it into a rod shape, and graphitizing at a high temperature. Artificial graphite thus graphitized can be crushed and classified. Note that graphite has hexagonal plate crystals and a layered structure. One kind of graphite particles may be used alone, or two or more kinds thereof may be used in combination.

(I) Oil absorption characteristics The oil absorption characteristics of graphite particles are determined by the method specified in JIS K6217-4: 2008 (carbon black for rubber-basic characteristics-part 4: how to determine the amount of oil adsorbed (including compressed material)). It is indicated by the measured DBP oil absorption.
Specific examples of the measurement method include the following methods. That is, first, 20 g of graphite particles are weighed using an absorption measuring device (trade name: S410C, manufactured by Asahi Research Institute, Inc.) and then charged into the mixing chamber of the device. In the mixing chamber, the graphite particles are mixed at 125 revolutions / minute by a rotating blade driven by a motor, DBP is dropped at a constant dropping speed, and absorbed by the graphite particles, and the torque at that time can be measured. The torque measured at that time increases with time, but when the graphite particles can no longer absorb DBP, the surroundings of the graphite particles are covered with DBP, and the torque rapidly decreases. 70% point of the maximum torque is determined as the end point, the dropping amount of DBP at that time, DBP oil absorption for the graphite particles ^(cm 3 / 100g) is calculated.

  When the graphite particles are contained in a dispersed state in the silicone rubber as in the elastic layer shown in FIG. 2, the graphite particles are isolated from the silicone rubber by the following method, and the DBP oil absorption is measured. That's fine. That is, a silicone rubber containing graphite particles is heated at a high temperature of 500 ° C. or higher in a nitrogen atmosphere, and the silicone rubber is incinerated and removed to isolate the graphite particles and measure the DBP oil absorption. .

In addition curable liquid silicone rubber composition according to the present embodiment, the graphite particles, DBP oil absorption amount to contain graphite particles or less 80 cm ^3/100 g or more 150 cm ^3/100 g. DBP absorption, graphite particles in the range of 80~150cm ³ / 100g is, for example, also the content of the addition-curable liquid silicone rubber mixture is a such a small amount of 30 vol% or less, addition-curable liquid silicone High thermal conductivity (for example, 1.1 W / (m · K) or more) can be imparted to the cured product of the rubber mixture. And even when such high DBP oil absorption graphite particles are used, the addition-curable liquid silicone rubber mixture according to this embodiment has a weight average molecular weight of 5500 or more and 65000 or less as the component (b) as a crosslinking agent. As a result, it is difficult for the component (b) to be taken into the graphite particles, so that it is difficult to inhibit curing.

(Ii) Content (filling amount)
The content of graphite particles in the addition-curable liquid silicone rubber mixture is preferably 13 to 30% by volume with respect to the entire silicone rubber mixture (100% by volume). If the content of the graphite particles is 13% by volume or more, an elastic layer having high thermal conductivity can be easily formed. If the content of the graphite particles is 30% by volume or less, it is easy to form an elastic layer having an appropriate hardness, and an appropriate stress is easily applied to the silicone rubber.

  In addition, when the addition-curable liquid silicone rubber mixture is cured to form an elastic layer, for example, the content (filling amount) of the graphite particles is preferably set as follows. That is, the content of the graphite particles in the elastic layer is preferably 13% by volume or more and 30% by volume or less.

  The contents of the cured product of addition curable liquid silicone rubber and graphite particles in the elastic layer were measured by a thermogravimetric apparatus (for example, TGA / SDTA851e (trade name), manufactured by METTLER TOLEDO Co., Ltd.). Is possible.

  Specifically, about 20 to 50 mg of the elastic layer portion cut out from the electrophotographic member with a blade or the like is used as a sample, and measurement is performed using an alumina pan.

  First, the sample placed on an alumina pan was put into a sample chamber, and the sample chamber was heated from room temperature (25 ° C.) to 1100 ° C. in a nitrogen atmosphere at a rate of temperature increase of 20 ° C./min. Increase the temperature with. The addition-curable liquid silicone rubber (cured product) is thermally decomposed by keeping it constant at 1100 ° C. for 30 minutes in a nitrogen atmosphere. Thereafter, the graphite particles are burned in a high-temperature oxygen atmosphere while maintaining the temperature at 1100 ° C. From the measured mass reduced at that time, the mass ratio of the addition-curable liquid silicone rubber (cured product) and the graphite particles contained in the sample can be confirmed. From the measurement result (mass) and density, the volume of each of the addition-curable liquid silicone rubber (cured product) and the graphite particles can be calculated, and the content of these in the elastic layer can be calculated.

(Iii) Average particle diameter It is preferable that the average particle diameter of a graphite particle is 3 micrometers or more and 40 micrometers or less. If the average particle diameter is 3 μm or more, even if a large amount of graphite particles is added to improve thermal conductivity, an increase in the viscosity of the addition-curable liquid silicone rubber before curing can be easily suppressed. Moreover, if the average particle diameter is 40 μm or less, it can be easily suppressed that the rubber surface of the electrophotographic member becomes rough and the image quality has a grainy unevenness.
The average particle size of the graphite particles is more preferably 5 μm or more from the viewpoint of viscosity and 30 μm or less from the viewpoint of hardness uniformity.

  The average particle size of the graphite particles can be measured by a laser diffraction / scattering particle size distribution measuring device (trade name: MT3100II, Microtrack Bell Co., Ltd.). Here, the average particle diameter of the graphite particles means a so-called median diameter. The median diameter means a particle diameter when the accumulation in a graph representing the volume average particle diameter as a cumulative distribution when the particle diameter distribution measurement is performed is 50%.

(2-1-3) Filler The addition-curable liquid silicone rubber mixture can contain titanium oxide, iron oxide, silica, and the like as fillers in order to improve heat resistance and durability in addition to graphite particles. The type and content of the filler in the addition-curable liquid silicone rubber mixture may be appropriately selected and adjusted within a range not impairing the effects of the present invention.

(2-2) Thickness of elastic layer In the electrophotographic belt, the thickness of the elastic layer is preferably 0.1 mm or more and 1.0 mm or less from the viewpoint of heat transfer and elasticity. In the electrophotographic roller, the thickness of the elastic layer is preferably 2.0 mm or more and 5.0 mm or less, and 2.5 mm or more and 4.0 mm or less from the viewpoint of heat transfer and elasticity. More preferred.

(2-3) Thermal conductivity in the thickness direction of the elastic layer The thermal conductivity (λ) in the thickness direction of the elastic layer is 1.1 W / (m · K) or more and 5.0 W / (m · K) or less. . By setting the thermal conductivity to 1.1 W / (m · K) or more, heat transfer from the back surface of the elastic layer of the electrophotographic member to the surface can be performed more efficiently. Here, the surface of the electrophotographic member is a surface in contact with the toner. The higher the thermal conductivity, the better. However, from the viewpoint of the hardness and strength of the elastic layer, the practically achievable thermal conductivity is 5.0 W / (m · K) or less. A method for measuring the thermal conductivity will be described later.

(2-4) Tensile elastic modulus of the elastic layer The tensile elastic modulus of the elastic layer is 0.1 MPa or more and 4.0 MPa or less. If the tensile elastic modulus is 0.1 MPa or more, it is considered that the addition-curable liquid silicone rubber constituting the elastic layer is sufficiently cured, and if it is 4.0 MPa or less, elasticity can be imparted to the electrophotographic member. . A method for measuring the tensile elastic modulus will be described later.

(2-5) Elastic Layer Formation Method The elastic layer can be formed by a method such as a ring coating method, a blade coating method, a nozzle coating method, and a mold molding method (Japanese Patent Publication No. 2001-62380 and Japanese Patent Publication). (See 2002-213432). By using these methods, the elastic layer can be formed on the substrate by heating and crosslinking the addition-curable liquid silicone rubber mixture supported on the substrate. In addition, ultraviolet rays can also be used when the addition curable liquid silicone rubber mixture is cured.

(3) Substrate (base material)
In the electrophotographic belt, an endless belt-shaped base is used. As the material, a nickel alloy, a metal such as stainless steel, or a resin such as polyimide can be used. An adhesive layer for imparting a function of improving the adhesion to the elastic layer can be provided on the outer peripheral surface of the substrate. That is, the elastic layer is provided on the outer peripheral surface of the substrate, and another layer such as an adhesive layer can be provided between the elastic layer and the substrate. Further, a protective layer for suppressing wear due to contact with the heater and a sliding layer for improving slidability with the heater can be provided on the inner peripheral surface of the substrate.

  A columnar or cylindrical substrate is used in the electrophotographic roller. As a material, a metal or an alloy such as aluminum or iron, or a heat resistant resin such as polyimide can be used.

(4) Surface layer of electrophotographic member (release layer)
The surface layer as the release layer preferably contains, for example, a fluororesin in order to make it difficult for the toner to adhere to the surface of the electrophotographic member. Specific examples of the fluororesin include the following. Tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer (PFA), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP).

  Further, the surface layer may contain a filler for the purpose of controlling the thermophysical properties within a range that does not impair the moldability and releasability.

  The thickness of the surface layer is preferably 10 μm or more and 100 μm or less. If the thickness of the surface layer is 10 μm or more, sufficient durability can be easily obtained, and if it is 100 μm or less, the electrophotographic member is maintained by maintaining the elasticity of the elastic layer when laminated on the elastic layer. It can be easily suppressed that the surface hardness of the heating member (for example, the heating member) becomes too high.

(4-1) Surface Layer Formation Method The surface layer formation method is not particularly limited, and for example, the following method can be used. That is, a method in which a fluororesin molded into a tube shape is coated on an elastic layer through an adhesive layer, or a fluororesin fine particle directly or dispersed in a solvent is applied to the elastic layer surface. Drying, melting and baking after coating. Hereinafter, these methods will be described in more detail.

(4-1-1) Formation of surface layer by coating with fluororesin tube The inner surface of the fluororesin tube is pretreated with sodium treatment, excimer laser treatment, ammonia treatment, etc., to activate the surface and improve adhesiveness. I can do it.

  FIG. 3 is a schematic diagram illustrating an example of a process of covering the elastic layer 2 with the fluororesin tube 6 as a surface layer via the adhesive layer 5.

  Specifically, an adhesive is applied to the surface of the elastic layer 2 to form the adhesive layer 5. The adhesive will be described in detail later. The outer surface of the adhesive layer 5 is covered with a fluororesin tube 6 as a surface layer and laminated.

  As the adhesive, it is preferable to use an addition-curable silicone rubber containing a self-adhesive component. Specifically, the silicone rubber contains an organopolysiloxane having a plurality of unsaturated aliphatic groups typified by vinyl groups in the molecular chain, a hydrogen organopolysiloxane, and a platinum compound as a crosslinking catalyst. Can be used. This silicone rubber is cured by an addition reaction. As the adhesive made of such an addition-curable silicone rubber, a known adhesive can be used.

  Although not required when the base 1 is a core metal capable of maintaining its shape, when using a thin base 1 such as a resin belt or a metal sleeve used for a belt-shaped electrophotographic member, In order to prevent deformation, it is desirable to hold the base body 1 by fitting it around the core.

  The coating method of the fluororesin tube 6 is not particularly limited, and a method of coating an adhesive as a lubricant, a method of expanding and coating the fluororesin tube 6 from the outside, and the like can be used.

  After the coating, the surplus adhesive remaining between the elastic layer 2 and the fluororesin tube 6 can be removed by using a means (not shown). The thickness of the adhesive layer 5 after being handled is preferably 20 μm or less. If the thickness of the adhesive layer 5 is 20 μm or less, it is easy to suppress the increase in hardness of the electrophotographic member, and even when used as a heating member, it has good follow-up to the unevenness of paper and is used as a pressure member In addition, a good fixed image can be easily obtained without narrowing the nip width during fixing. Next, the adhesive layer 5 is cured by heating with a heating means such as an electric furnace for a predetermined time, and both ends are processed to a desired length as necessary, so that the electrophotography of the present invention is performed. A member for use can be obtained.

(4-1-2) Formation of surface layer by fluororesin coating For fluororesin coating processing for surface layer formation, use methods such as electrostatic coating method of fluororesin fine particles and spray coating of fluororesin paint Can do.

  When using the electrostatic coating method, first apply electrostatic coating of fluororesin fine particles to the inner surface of the mold, and heat the mold to the melting point or higher of the fluororesin, thereby forming a thin film of fluororesin on the inner surface of the mold. Form. After that, after the inner surface is bonded, the base is inserted, the elastic layer material is injected between the base and the fluororesin, cured, and then demolded together with the fluororesin. A member for use can be obtained.

  When spray coating is used, a fluororesin paint is used. The fluororesin coating forms a so-called dispersion liquid in which fluororesin fine particles are dispersed in a solvent by a surfactant or the like. The fluororesin dispersion liquid is also commercially available and can be easily obtained. This dispersion liquid is supplied to a spray gun and sprayed in a mist state by a gas pressure such as air. If necessary, a member having an elastic layer bonded with a primer or the like is disposed at a position facing the spray gun, the member is rotated at a constant speed, and the spray gun is translated in the axial direction of the substrate. Thereby, the coating film of the fluororesin paint can be uniformly formed on the elastic layer surface. Thus, the fluororesin surface layer can be formed by heating the member on which the fluororesin coating film is formed to a temperature equal to or higher than the melting point of the fluororesin coating film using heating means such as an electric furnace.

(5) Method for Producing Electrophotographic Member The electrophotographic member according to one aspect of the present invention is the surface of another layer formed on the outer peripheral surface of the substrate, that is, directly on the surface of the substrate or on the surface of the substrate. And forming an elastic layer by forming a coating film of the addition-curable liquid silicone rubber mixture according to one embodiment of the present invention and curing the addition-curable liquid silicone rubber in the coating film. Can do. Moreover, it can also have the process of forming a surface layer (release layer) and a sliding layer as needed.

(6) Fixing Device The fixing device according to one embodiment of the present invention will be specifically described.

  FIG. 4 is a cross-sectional view of one embodiment of the fixing device. This fixing device is a so-called on-demand type thermal fixing device, and is a film heating type thermal fixing device using a ceramic heater as a heating source. Hereinafter, an outline of the configuration will be described by taking an on-demand type thermal fixing device as an example. The fixing device according to the present invention is not limited to this form, and a heat roll type fixing device using a halogen heater as a heat source, or induction heating (IH) that generates heat by energizing a coil. ) Type fixing device.

  In FIG. 4, the film guide member 401 has a substantially semicircular cross section and a bowl shape, and has a horizontally long shape in which the direction parallel to the longitudinal direction of the pressurizing rotating body 404 is the width direction.

  The heater 402 is a horizontally long heater accommodated and held in a groove formed along the width direction at the approximate center of the lower surface of the film guide member 401. An electrophotographic belt 403 according to one embodiment of the present invention is externally fitted to a film guide member 401 equipped with a heater 402. The heater 402 and the electrophotographic belt 403 are components of the heating unit of the fixing device according to FIG. 4, and the heater 402 functions as a heating member that directly contacts the toner and heats the toner. This is a member for heating the belt 403. The heater 402 is disposed inside the electrophotographic belt 403 and in contact with the (endless belt-shaped) base (the inner peripheral surface) of the electrophotographic belt 403.

  The film guide member 401 is a molded product made of a heat resistant resin such as PPS (polyphenylene sulfite) or a liquid crystal polymer.

  The heater 402 has a configuration in which a heating resistor is provided on a ceramic substrate, for example. The heater 402 is composed of a horizontal and thin heater substrate 402a made of alumina, and a linear or narrow strip Ag / A which is formed on the surface side (film sliding surface side) along the longitudinal direction of the heater substrate 402a. And a Pd energization heating element (heating resistor) 402c. The heater 402 has a thin glass surface protective layer 402d that covers and protects the energization heating element 402c. A thermistor (temperature sensing element) 402b is in contact with the back side of the heater substrate 402a. The heater 402 can be controlled to maintain a predetermined fixing temperature by power control means (not shown) including a temperature detecting element 402b after the temperature is rapidly raised by supplying power to the energization heating element 402c. The fixing temperature is a target temperature on the surface of the heating member (electrophotographic belt) and is appropriately set depending on the printing speed, paper type, heating member configuration, and toner type. A general fixing temperature is 150 ° C. or higher and 200 ° C. or lower.

  A pressurizing rotating body (pressing member) 404 is disposed opposite to the lower surface of the heater 402 and is in pressure contact with the heater 402 via an electrophotographic belt (heating member) 403. The pressurizing rotating body 404 includes a base body 404a, an elastic layer 404b, and a surface layer 404c.

  The pressurizing rotating body 404 is pressed against the surface protective layer 402d of the heater 402 via the electrophotographic belt 403 by a predetermined pressurizing mechanism (not shown). The elastic layer 404b of the pressurizing rotating body 404 is elastically deformed in accordance with the applied pressure, and a predetermined required for heating and fixing the unfixed toner image T between the surface of the pressurizing rotating body 404 and the surface of the electrophotographic belt 403. A nip N having a width is formed. The pressurizing force is appropriately set depending on the paper type, size, toner type, and fixing device configuration that are products. Usually, the applied pressure is set to about 10 kgf (98 N) to 70 kgf (686 N). The recording material P as the material to be heated is introduced into the nip portion N, and the recording material P is heated by being nipped and conveyed. The pressurizing rotating body 404 is rotationally driven in the counterclockwise direction indicated by the arrow b at a predetermined peripheral speed when the driving force of the driving source M is transmitted through a gear (power transmission mechanism) (not shown). The electrophotographic belt 403 rotates in the direction of arrow a following the rotation of the pressurizing rotary body 404 when the pressurizing rotary body 404 is rotationally driven in the counterclockwise direction of arrow b during image formation. .

  Hereinafter, the present invention will be described more specifically with reference to examples.

[Example 1]
(1) Preparation of addition curable liquid silicone rubber mixture (a) As a component, a silicone polymer having an unsaturated aliphatic group at both ends (weight average molecular weight 28000, kinematic viscosity 1000 mm ² / sec, hereinafter “Vi-1” 100 parts by mass was prepared. This silicone polymer is a silicone polymer in which, in Structural Formula 5, R ₂ is a vinyl group, and 0.5 mol% of vinyl groups are introduced into both terminal portions in terms of silicon atom ratio in Vi-1.

Next, as a component (b), 11.0 parts by mass of a silicone polymer having an active hydrogen group bonded to silicon (weight average molecular weight 60,000, kinematic viscosity 9000 mm ² / sec, hereinafter referred to as “SiH-1”) And added to Vi-1. In addition, the silicone polymer as the component (b) is structural formula 6 in which R ₇ is a methyl group, and the amount of active hydrogen groups bonded to the silicon atom is 6.0 in terms of the silicon atom ratio in SiH-1. It is a silicone polymer introduced in mol%.

  Further, 0.15 part by mass of a hydrosilylation catalyst (platinum catalyst: platinum carbonylcyclovinylmethylsiloxane complex vinyl methylcyclosiloxane 2.0 mass%) was added to the mixture of component (a) and component (b). By sufficiently mixing, a base polymer (addition-curable liquid silicone rubber) was obtained.

To this base polymer, graphite particles a (trade name: UF-G30, manufactured by Showa Denko KK, average particle size 10 [mu] m, DBP oil absorption of 87cm ^3/100 g) was 63 parts by mass, by mixing thoroughly, An addition-curable liquid silicone rubber mixture containing 20% by volume of graphite particles was obtained.

(2) Preparation of fixing belt Next, a fixing belt was prepared as follows using the obtained addition-curable liquid silicone rubber mixture.

  A nickel electroformed endless sleeve having an inner diameter of 55 m, a width of 420 mm, and a thickness of 65 μm was prepared as a substrate. During a series of manufacturing processes, the endless sleeve (endless sleeve) was handled with a core inserted therein.

  First, a primer (trade name: DY39-051 A / B, manufactured by Toray Dow Corning Co., Ltd.) is applied almost uniformly on the outer peripheral surface of the substrate, and after drying the solvent, baking is performed in an electric furnace at 160 ° C. for 30 minutes. Went.

  The addition-curable liquid silicone rubber mixture was applied to the primer-treated substrate at a thickness of 450 μm by a ring coating method. The endless belt provided with the silicone rubber mixture is heated in an electric furnace at 160 ° C. for 1 minute (primary curing), and further heated in an electric furnace set at 200 ° C. for 4 hours to cure the silicone rubber mixture. (Secondary curing).

  Next, while rotating the surface of the obtained endless belt at a moving speed of 20 mm / sec in the circumferential direction, using an ultraviolet lamp installed at a distance of 10 mm from the surface, ultraviolet rays are applied to the surface of the secondarily cured silicone rubber mixture. Irradiation was performed. The UV lamp is a low-pressure mercury UV lamp (trade name: GLQ500US / 11, manufactured by Toshiba Lighting & Technology Corp. (formerly Harrison Toshiba Lighting Co., Ltd.)). A layer was formed.

  Next, after cooling to room temperature, an addition-curable silicone rubber adhesive (trade name: SE1819CV A / B, manufactured by Toray Dow Corning Co., Ltd.) is formed to a thickness of 20 μm on the surface of the elastic layer of the endless belt. Was applied almost uniformly.

  Next, a fluororesin tube (trade name: KURAFLON-LT, manufactured by Kurashiki Boseki Co., Ltd.) having an inner diameter of 54 mm and a thickness of 40 μm was laminated on this adhesive. Thereafter, the surface of the belt was uniformly treated from above the fluororesin tube, so that excess adhesive was handled so as to be sufficiently thin from between the elastic layer and the fluororesin tube.

  The obtained endless belt was heated in an electric furnace set at 200 ° C. for 1 hour to cure the adhesive and fix the fluororesin tube (surface layer) on the elastic layer. Both end portions of the obtained endless belt were cut to obtain a fixing belt having a width of 348 mm.

(3) Characteristic evaluation of fixing belt (thermal conductivity / tensile modulus of elastic layer)
First, a primer treatment was performed on the substrate by the same method as that for producing the fixing belt, and then an elastic layer (elastic layer after secondary curing) having a thickness of 450 μm was formed by a ring coating method.

(3-1) Thermal conductivity in the thickness direction of the elastic layer The thermal conductivity (λ) in the thickness direction of the elastic layer was calculated from the following calculation formula 2.

Formula 2
λ = α × C _p × ρ
(In Formula 2, λ is the thermal conductivity in the thickness direction of the elastic layer (W / (m · K)), α is the thermal diffusivity in the thickness direction (mm ² / sec), and C _p is the constant pressure specific heat (J / (G · K)), ρ represents the true density (g / cm ³ ).
Here, each value of the thermal diffusivity in the thickness direction of the elastic layer, the constant pressure specific heat, and the true density was obtained by the following method.

・ Thermal diffusivity (α)
The thermal diffusivity in the thickness direction of the elastic layer was measured under a room temperature (25 ° C.) condition using a periodic heating method thermophysical property measuring device (trade name: FTC-1, manufactured by ULVAC-RIKO Co., Ltd.). About the sample piece, the elastic layer 250 μm portion excluding 100 μm from the surface layer side and 100 μm from the substrate side in the elastic layer 450 μm is cut into a sample piece having an area of 8 × 12 mm and a thickness of 250 μm with a cutter, for a total of 5 samples. A piece was made. When each sample was measured five times in total, the average value of the five samples was 0.88 mm ² / sec.

・ Constant-pressure specific heat (C _p )
The constant-pressure specific heat of the elastic layer was measured using a differential scanning calorimeter (trade name: DSC823e, manufactured by METTLER TOLEDO).

Specifically, an aluminum pan was used as a sample pan and a reference pan. First, as a blank measurement, after keeping both pans empty for 10 minutes at a constant temperature of 15 ° C., the temperature was increased to 215 ° C. at a temperature increase rate of 10 ° C./min, and further for 10 minutes at 215 ° C. Measurements were carried out with a program kept at a constant temperature. Next, 10 mg of synthetic sapphire having a known constant pressure specific heat was used as a reference material, and measurement was performed using the same program. Next, a 10 mg measurement sample having the same amount as that of the reference sapphire was cut out from the elastic layer portion, set in a sample pan, and measured with the same program. These measurement results were analyzed using the specific heat analysis software attached to the differential scanning calorimeter, and the constant-pressure specific heat (C _p ) at 25 ° C. was calculated from the arithmetic average value of five measurements. The constant pressure specific heat of the elastic layer was 1.03 J / (g · K).

・ True density (ρ)
The true density of the elastic layer was measured using a dry automatic densimeter (trade name: Accupic 1330-01, manufactured by Shimadzu Corporation).

Specifically, using a 10 cm ³ sample cell, the sample was cut from the elastic layer so as to satisfy 80% of the cell volume, and placed in the sample cell. After measuring the mass of this sample, a cell was set in the measurement unit in the apparatus, and helium was used as a measurement gas, and after 10 gas replacements, volume measurement was performed 10 times. The true density (ρ) was calculated from the mass of the sample and the measured volume. The true density of the elastic layer was 1.24 g / cm ³ .

(3-2) Tensile elastic modulus of elastic layer In order to confirm that the elastic layer was sufficiently cured, the tensile elastic modulus of the elastic layer was measured.

  Specifically, a dumbbell shape was cut out from the elastic layer with a punching die, and cut into a size of 20 mm in length, 4 mm in width, and 300 μm in thickness. Next, the cut elastic layer was set on an attachment for measuring the tensile elastic modulus of a dynamic viscoelasticity measuring apparatus (trade name: Strograph EII, manufactured by UBM Co., Ltd.), and the tensile elastic modulus (MPa) was measured.

(4) Evaluation of fixing belt The fixing belt obtained by the method described in (2) above was mounted as a heating member on a fixing device unit of an electrophotographic image forming apparatus (trade name: imagePress C800, manufactured by Canon Inc.). . This fixing device unit was mounted on the electrophotographic image forming apparatus. Using this electrophotographic image forming apparatus, A4 size paper (trade name: high white paper GF-C081, basis weight 81 g / m ² , manufactured by Canon Inc.) is fed vertically (the short side is in the longitudinal direction of the fixing belt). And 1000 evaluation images were continuously printed. As the evaluation image, an A4 size paper having a cyan toner and a magenta toner formed on the entire surface at 100% density was used. The 1000th evaluation image was visually observed. Further, when the continuous printing of 1000 evaluation images was completed, the fixing belt was visually observed. The observation results were evaluated according to the following criteria.

(Evaluation criteria)
Rank A: No defect due to poor fixing is observed in the 1000th image. In addition, regarding the fixing belt after continuous printing of 1000 evaluation images, neither peeling of the elastic layer from the substrate nor damage of the elastic layer is observed.
Rank B: A defect due to poor fixing is found in the 1000th image. Alternatively, with respect to the fixing belt after continuous printing of 1000 evaluation images, peeling of the elastic layer from the substrate or damage to the elastic layer is observed.

[Examples 2 to 11 and Comparative Examples 1 to 4]
Except that the types, physical properties and filling amounts shown in Table 1 were used, except that a silicone polymer having an unsaturated aliphatic group (Vi), a silicone polymer having an active hydrogen group bonded to silicon (SiH), and graphite particles were used. A fixing belt was produced in the same manner as in Example 1. Then, for the obtained fixing belt, the evaluations (3) and (4) were performed in the same manner as in Example 1. The results are shown in Table 1, respectively. Here, in Comparative Examples 1 to 4, since the elastic layer was not sufficiently cured due to poor curing, neither the thermal conductivity in the thickness direction nor the tensile elastic modulus was measured. Further, the fixing belts according to Comparative Examples 1 to 4 were not used for evaluation (4).

In Table 1, the weight average molecular weight, kinematic viscosity, and silicon atom specific active hydrogen group amount in the component (SiH) of the silicone polymer (SiH) having active hydrogen groups bonded to silicon are as follows.
SiH-2: (weight average molecular weight: 6000, kinematic viscosity 130 mm ² / sec, silicon atom specific active hydrogen group amount: 7.5 mol% introduced).
SiH-3: (weight average molecular weight: 2000, kinematic viscosity 35 mm ² / sec, silicon atom specific active hydrogen group amount: 27.5 mol% introduced).
Further, these silicone polymers are silicone polymers in which R ₇ is a methyl group in the structural formula 6.

In Examples 4 to 11 and Comparative Examples 2 to 4, the following graphite particles were used.
- Examples 4-6 and Comparative Example 2: Graphite particles b (trade name: SNE-10G, SEC Carbon Co., Ltd., average particle size 11 [mu] m, DBP oil absorption 140cm ³ / 100g).
- Examples 7-9 and Comparative Example 3: Graphite particles c (trade name: SNO-5, SEC Carbon Co., Ltd., average particle diameter of 5 [mu] m, DBP oil absorption of 105 cm ^3/100 g).
· Examples 10-11 and Comparative Example 4; graphite particles d (trade name: SGP-10, SEC Carbon Co., Ltd., average particle size 10 [mu] m, DBP oil absorption of 83cm ³ / 100g).

1 Substrate (base material)
2 Elastic layer 2a Cured product of addition curable liquid silicone rubber 2b Graphite particles 3 Adhesive layer 4 Surface layer (release layer)
5 Adhesive Layer 6 Fluoropolymer Tube 402 Heater 403 Electrophotographic Belt (Heating Member)
404 Rotating body for pressurization (pressurizing member)

Claims (18)

An electrophotographic member having a substrate and an elastic layer on the substrate,
The elastic layer includes a cured product of an addition curable liquid silicone rubber mixture containing graphite particles,
DBP (dibutyl phthalate) oil absorption amount of the graphite particles is ^not more than 80 cm 3/100 g or more 150 cm ^3/100 g,
The thermal conductivity in the thickness direction of the elastic layer is 1.1 W / (m · K) or more and 5.0 W / (m · K) or less, and
The elastic modulus of the elastic layer is 0.1 MPa or more and 4.0 MPa or less,
An electrophotographic member characterized by the above.   The electrophotographic member according to claim 1, wherein a content of the graphite particles in the elastic layer is 13% by volume or more and 30% by volume or less.   The electrophotographic member according to claim 1, wherein the graphite particles have an average particle diameter of 3 μm or more and 40 μm or less. The electrophotographic member is an electrophotographic member having an endless belt shape,
The electrophotographic member according to claim 1, wherein the base has an endless belt shape, and the elastic layer is located on an outer peripheral surface of the endless belt-shaped base. .   The electrophotographic member according to claim 4, wherein the elastic layer has a thickness of 0.1 mm to 1.0 mm.   The electrophotographic member according to claim 4, further comprising a surface layer on the outer peripheral surface of the elastic layer.   The member for electrophotography according to claim 6 whose thickness of said surface layer is 10 micrometers or more and 100 micrometers or less. An organopolysiloxane having an unsaturated aliphatic group, an organopolysiloxane having an active hydrogen bonded to silicon, a catalyst, and graphite particles;
DBP (dibutyl phthalate) oil absorption amount of the graphite particles is ^not more than 80 cm 3/100 g or more 150 cm ^3/100 g, and,
The weight average molecular weight of the organopolysiloxane having active silicon bonded to silicon is 5500 or more and 65000 or less.
An addition curable liquid silicone rubber mixture.   The addition-curable liquid silicone rubber mixture according to claim 8, wherein the content of the graphite particles in the addition-curable liquid silicone rubber mixture is 13% by volume or more and 30% by volume or less.   The addition-curable liquid silicone rubber mixture according to claim 8 or 9, wherein the graphite particles have an average particle size of 3 µm or more and 40 µm or less.   The addition-curable liquid silicone rubber mixture according to any one of claims 8 to 10, wherein the organopolysiloxane having active hydrogen bonded to silicon has a weight average molecular weight of 6000 or more and 60000 or less. The addition curing type according to any one of claims 8 to 11, wherein the organopolysiloxane having active silicon-bonded hydrogen has a kinematic viscosity at a temperature of 25 ° C of 130 mm ² / sec to 9000 mm ² / sec. Liquid silicone rubber mixture.   The amount of active hydrogen bonded to silicon in the organopolysiloxane having active hydrogen bonded to silicon is 1 mol% or more and 10 mol% or less with respect to 1 mol of the silicon. The addition-curable liquid silicone rubber mixture according to any one of the above.   The addition-curable liquid silicone rubber mixture according to any one of claims 8 to 13, wherein the organopolysiloxane having an unsaturated aliphatic group has a weight average molecular weight of 20,000 to 80,000. The addition-curable liquid silicone rubber mixture according to any one of claims 8 to 14, wherein the organopolysiloxane having an unsaturated aliphatic group has a kinematic viscosity at a temperature of 25 ° C of 1000 to 30000 mm ² / sec. A method for producing an electrophotographic member having a substrate and an elastic layer on the substrate,
An electrophotographic process comprising the step of curing the coating film of the addition-curable liquid silicone rubber mixture according to any one of claims 8 to 15 on the substrate to form the elastic layer. Manufacturing method of member. A fixing device having a heating member and a pressure member arranged to face the heating member,
The fixing device, wherein the heating member is the electrophotographic member according to claim 1.   The fixing device according to claim 17, wherein the heating member is the electrophotographic member according to claim 4, and a heater is disposed in contact with the inner peripheral surface of the base.

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