JP6976838B2 - Additive-curing liquid silicone rubber mixture, electrophotographic components and their manufacturing methods, and fixing devices - Google Patents

Description

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

The electrophotographic apparatus includes a heating member and a pressurizing member arranged to face the heating member in order to fix the unfixed toner image formed on the recording medium to the recording medium. (Heat fixing device) is used.

Usually, in a fixing device used in an electrophotographic method, 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 that a recording medium can be pressed against each other. There is. Then, a recording medium such as paper holding an image of unfixed toner is introduced into the pressure 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 arranged so as to face 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 compression member. The heating member includes a fixing roller, a fixing film and a fixing belt depending on the form thereof. 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 thermally 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 as compared with a thermally conductive filler such as alumina. That is, graphite can impart high thermal conductivity to the elastic layer even if the content is relatively small as compared with alumina. However, it may be difficult to sufficiently cure the addition-curing liquid silicone rubber mixture in which graphite is blended in the addition-curing liquid silicone rubber. When graphite is used to improve the thermal conductivity of the elastic layer containing the cured product of the addition-curable liquid silicone rubber, it is necessary to develop a technique for stably curing the addition-curable liquid silicone rubber. The present inventors recognized.

One aspect of the present invention is to provide an electrophotographic member having an elastic layer in which graphite (graphite particles) are dispersed in a silicone rubber and having an elastic layer having high thermal conductivity in the thickness direction, and a method for manufacturing the same. It is aimed at.

In addition, another aspect of the present invention is aimed at providing an addition-curable liquid silicone rubber mixture having sufficient curability.

Yet another aspect of the present invention is to provide 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, wherein the elastic layer contains 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 Provided is an electrophotographic member having a tensile elastic modulus of .0 W / (m · K) or less and a tensile elastic modulus of 0.1 MPa or more and 4.0 MPa or less.

Further, according to another aspect of the present invention, it contains an organopolysiloxane having an unsaturated aliphatic group, an organopolysiloxane having an active hydrogen bonded to silicon, a catalyst, and graphite particles, and the 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 a method for manufacturing an electrophotographic member having a substrate and an elastic layer on the substrate, wherein a coating film of the addition-curable liquid silicone rubber mixture on the substrate is formed. Provided is a method for manufacturing an electrophotographic member, which comprises a step of curing to form the elastic layer.

According to still another aspect of the present invention, a fixing device having a heating member and a pressurizing member arranged facing the heating member, wherein the heating member is the electrophotographic member. Equipment is provided.

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

Further, according to still another aspect of the present invention, it is possible to obtain a fixing device capable of forming a high-quality electrophotographic image.

(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 a cross-sectional view. It is sectional drawing of the elastic layer of the electrophotographic member which concerns on one aspect of this invention. It is a schematic diagram of an example for demonstrating the process of laminating a fluororesin surface layer. It is explanatory drawing of the fixing device which concerns on one aspect of this invention.

The present inventors have investigated 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 amount of DBP (dibutyl phthalate) oil absorbed by the graphite particles used, the more remarkable the inhibition of curing of the addition-curable liquid silicone rubber mixture. From such experimental results, the present inventors considered that the curing inhibition of the addition-curable liquid silicone rubber mixture was caused by the following reasons. That is, the organopolysiloxane having active hydrogen bonded to a silicon atom, which functions as a cross-linking agent, is absorbed into the pores of the graphite particles, and the hydrosilylation reaction does not proceed sufficiently, so that curing is inhibited. I considered. Therefore, the present inventors considered that increasing the molecular weight of the cross-linking agent makes it difficult for the cross-linking agent to be absorbed into the pores of the graphite particles, and conducted a study. As a result, it has been found that even an addition-curable liquid silicone rubber mixture containing graphite particles having a large DBP oil absorption can be sufficiently cured by increasing the molecular weight of the cross-linking agent, and the present invention has been made. ..

Japanese Patent Publication 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. It is described that the conductive silicone rubber composition in which a large amount of the carbon-based conductivity-imparting agent is blended with the silicone rubber has a reduced curability. However, carbon black is the only carbon-based conductivity-imparting agent specifically used in Examples and Comparative Examples of Japanese Patent Publication No. 8-113713, and no specific disclosure or suggestion regarding graphite is given. No.

The addition-curing liquid silicone rubber mixture according to one aspect of the present invention has an organopolysiloxane having active hydrogen bonded to a silicon atom, which is a cross-linking agent for the addition-curing liquid silicone rubber, having a weight average molecular weight of 5500 to 65,000. .. 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, it is possible to prevent the addition-curing liquid silicone rubber mixture from being cured. Further, the graphite particles having a high DBP oil absorption can efficiently increase the thermal conductivity of the silicone rubber. Therefore, the addition-curable liquid silicone rubber mixture according to one aspect of the present invention can give a silicone rubber having further improved thermal conductivity. Further, it is possible to provide an electrophotographic member having an elastic layer having further improved thermal conductivity.

Hereinafter, the present invention will be described in detail.

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

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

The electrophotographic belt shown in FIG. 1A has an endless belt-shaped substrate (base material) 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, the surface layer (release layer) 4 may be provided on the outer peripheral surface of the elastic layer 2. Further, the 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 cross section of the elastic layer of the electrophotographic member according to FIGS. 1A and 1B, that is, a cross section in a direction orthogonal to the longitudinal direction of the electrophotographic member. .. The elastic layer contains a cured product of an addition-curable liquid silicone rubber mixture, and the cured product is a cured silicone rubber as a matrix (cured product 2a of an addition-cured liquid silicone rubber) and graphite dispersed in the matrix. Includes particles 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 be done. That is, the elastic layer can be a cured product (solidified product) of the addition-curable liquid silicone rubber mixture, and can contain at least a cured product 2a of the addition-curable liquid silicone rubber and graphite particles 2b. ..

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

The electrophotographic member (fixing roller, fixing film, fixing belt, etc.) can be used as either or both of the heating member and the pressure member. When the electrophotographic member is used as a heating member, the elastic layer functions as a layer for imparting elasticity for following the unevenness of the paper at the time of fixing. Further, when the electrophotographic member is used as the pressure member, the elastic layer functions as a layer for imparting elasticity for ensuring the nip width at the time of fixing. In order to exhibit these functions, it is desirable to use uncured silicone rubber as the base material for forming the elastic layer. The uncured silicone rubber mainly includes an addition-curing type liquid silicone rubber and a miraculous type silicone rubber, but in the present invention, the addition-curing type liquid silicone rubber is used from the viewpoint of easily dispersing graphite particles and fillers.

The addition-curing liquid silicone rubber mixture used for producing the elastic layer will be described below.

(2-1) Additive Curing Type Liquid Silicone Rubber Mixture The addition curable type liquid silicone rubber mixture contains an addition curable type liquid silicone rubber and graphite particles. The addition-curing liquid silicone rubber mixture may further contain a filler described later.
Next, each component contained in the addition-curable liquid silicone rubber mixture will be described in detail.

(2-1-1) Additive-curing liquid silicone rubber As described above, the addition-curing liquid silicone rubber contains (a) an organopolysiloxane having an unsaturated aliphatic group and (b) active hydrogen bonded to silicon. It can contain an organopolysiloxane having (c) a platinum compound as a hydrosilylation (additional curing) catalyst. In the addition-curing liquid silicone rubber mixture, the content of these addition-curing liquid silicone rubber components (including platinum compound) 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.

(A) Component: Organopolysiloxane having an unsaturated aliphatic group The organopolysiloxane having an unsaturated aliphatic group (hereinafter, may be referred to as "component (a)") is an unsaturated aliphatic group 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 the intermediate unit represented by the middle unit and _R 1 _R 2 SiO represented by _R 1 _R 1 _SiO, with R ₁ R ₁ R _{2 SiO 1/2} A linear organopolysiloxane having a represented molecular terminal (see Structural Formula 1 below).

In structural formula 1, R ₁ independently represents a monovalent unsubstituted or substituted hydrocarbon group containing no unsaturated aliphatic group, R ₂ independently represents an unsaturated aliphatic group, and m and n represent unsaturated aliphatic groups. Each independently represents an integer of 0 or more, where m + n represents an integer of 1 or more.

One or both intermediate units selected from the intermediate unit represented by R ₃ SiO _3/2 and the intermediate unit represented by SiO _{4/2 , and represented by R 3} R ₃ R ₄ SiO _1/2. A branched organopolysiloxane having a molecular terminal (see Structural Formula 2 below).

In structural formula 2, R ₃ independently represents a monovalent unsubstituted or substituted hydrocarbon group containing no unsaturated aliphatic group, R ₄ independently represents an unsaturated aliphatic group, and Y represents an organopoly. Represents siloxane, where p and q each independently represent an integer greater than or equal to 0, where p + q represents an integer greater than or equal to 1.

It has a molecular terminal represented by _{R 5} R ₅ R ₅ SiO _{1/2 , an intermediate unit represented by R 5} R ₆ SiO, and, if necessary, an intermediate unit represented by R ₅ R ₅ SiO. Linear organopolysiloxane (see Structural Formula 3 below).

In structural formula 3, R ₅ independently represents a monovalent unsubstituted or substituted hydrocarbon group containing no unsaturated aliphatic group, R ₆ independently represents an unsaturated aliphatic group, and r is 0 or more. Represents an integer of, and s represents an integer of 3 or more.

In the structural formulas 1 to 3, the _{monovalent unsubstituted or substituted hydrocarbon group represented by R 1} , R ₃ and R ₅ , respectively, which is bonded to a silicon atom and does not contain an unsaturated aliphatic group, is used. For example, the following can be mentioned.

-Unsubstituted hydrocarbon group Alkyl group (eg, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, etc.); aryl group (eg, 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 manufacture. 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.

Further, in the structural formulas _1-3, respectively represented by R 2, _{R 4} and _{R 6,} the unsaturated aliphatic group bonded to a silicon atom, a vinyl group, an allyl group, a 3-butenyl group, 4-pentenyl A group, a 5-hexenyl group and the like can be exemplified. Here, all of R ₂ , R ₄ and R ₆ are preferably vinyl groups because they are easy to synthesize and handle, inexpensive, and easily carry out a crosslinking reaction.

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

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

In the structural formula 4, 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, R ₂ independently represents an unsaturated aliphatic group, and m represents a positive integer.

As the component (a), one kind may be used alone, or two or more kinds may be used in combination. For example, as the component (a), the organopolysiloxane represented by the structural formula 4 and the organopolysiloxane represented by the structural formula 5 may be blended and used.

From the viewpoint of facilitating the formability 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, It is preferably 1000 to 30000 mm ² / sec.

The weight average molecular weight of the component (a) can be measured by gel permeation chromatography (GPC) as a polystyrene-equivalent weight average molecular weight.

Here, the weight average molecular weight of the component (a) can be measured under the following conditions by using the method for measuring the molecular weight distribution by GPC.
The column is stabilized in a heat chamber at a temperature of 40 ° C., and toluene is flowed through the column at this temperature as a solvent at a flow rate of 1 mL / min. The molecular weight of the sample is measured by injecting 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)) into the column. In measuring the molecular weight of a sample, the molecular weight distribution of the sample is measured by using the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples (trade names: TSKgel standard polystyrenes "0005202" to "0005211", manufactured by Tosoh Corporation). Calculated from the relationship with the retention time. 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, a commercially available polystyrene gel column (trade name: Shodex GPC LF-804, manufactured by Showa Denko KK) is used in combination of three.

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

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

In the addition-curable liquid silicone rubber, the amount of unsaturated aliphatic groups 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 preferable. More preferably, it is 0.2 mol% or more and 1.0 mol% or less with respect to 1 mol of silicon atom.

(B) Component: Organopolysiloxane (crosslinking agent) having active hydrogen bonded to silicon
Organopolysiloxane having active hydrogen bonded to silicon (hereinafter, may be referred to as component (b)) is hydrosilylated with an unsaturated aliphatic group in component (a) by the catalytic action of a platinum compound. It functions as a cross-linking agent that forms a cross-linked structure.

As the component (b), any organopolysiloxane having a Si—H bond can be used, and for example, a component satisfying the following conditions can be preferably used. As the component (b), one type may be used alone, or two or more types (mixtures of) may be used in combination.

-From the viewpoint of forming a crosslinked structure by reaction with an organopolysiloxane having an unsaturated aliphatic group, the number of hydrogen atoms bonded to silicon atoms is 3 or more on average in one 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 a linear skeleton is preferable 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 cross-linking agent silicone polymer represented by the following structural formula 7.

In Structural Formula 6, R ₇ independently represents a monovalent unsubstituted or substituted hydrocarbon group containing no unsaturated aliphatic group, t represents an integer of 0 or more, and u represents an integer of 3 or more.

In Structural Formula 7, R ₈ independently represents a monovalent unsubstituted or substituted hydrocarbon group containing no unsaturated aliphatic group, v represents an integer of 0 or more, and w represents an integer of 3 or more.

Both R ₇ and R ₈ can be monovalent unsubstituted or substituted hydrocarbon groups bonded to silicon atoms 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, It is more preferred that all R ₇ and R _{8 are methyl groups.}

In the addition-curable liquid silicone rubber mixture according to one aspect 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 curing inhibition of the addition-curable liquid silicone rubber mixture. Further, if 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 decrease. The weight average molecular weight of the component (b) is more preferably 6000 or more and 60,000 or less.

The weight average molecular weight of the component (b) can be measured by the same method as the weight average molecular weight of the component (a) described above.
Further, the kinematic viscosity of the 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 above formula 1 is measured. As a specific measurement method, for example, the following measurement method can be mentioned. That is, first, a sample for which the viscosity should be measured (for example, an addition-curable liquid silicone rubber mixture) is applied to the sample table of the rotary viscometer described above, and a rotating plate is used to create a gap with the sample table described above. Stack them so that they are 105 μm, and sandwich the sample. The plate is then rotated to shear the sample. As a condition of the shear rate, the shear rate is increased from 0s ^-1 to 20s ^-1 at a ^{rate of 0.2s -1} per second, and then from 20s ^-1 to 0s ^-1 at 0.2s ^-1 per second. Decrease at a rate. The maximum value among the viscosity values measured in this process is taken as the viscosity μ in the above calculation formula 1 as a representative value.

In the addition-curable liquid silicone rubber, the amount of active hydrogen groups bonded to silicon in the organopolysiloxane as the component (b) is 1 mol% or more with respect to 1 mol of the silicon atom in the component (b). It is preferably 10 mol% or less.

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

(2-1-2) Graphite particles As the graphite (graphite) particles, either artificial graphite particles or natural graphite particles can be used. As the particles of natural graphite, those obtained by crushing naturally produced graphite into fine particles can be used. Further, artificial graphite is obtained by crushing coke as a raw material, forming it into a rod shape, and graphitizing it at a high temperature. Artificial graphite that has been graphitized in this way can be crushed and classified. Graphite has hexagonal plate-like crystals and has a layered structure. One type of graphite particles may be used alone, or two or more types 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: Method for Obtaining Oil Adsorption Amount (including Compressed Material)). It is indicated by the measured DBP oil absorption.
Specific measurement methods include, for example, the following methods. That is, first, 20 g of graphite particles are weighed using an absorption amount measuring device (trade name: S410C, manufactured by Asahi Soken Co., Ltd.), and then charged into the mixing chamber of the device. In the mixing chamber, graphite particles can be mixed by a rotary blade driven by a motor at 125 rpm, and DBP can be dropped at a constant dropping speed to be 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 cannot absorb the DBP, the graphite particles are covered with the DBP and the torque drops sharply. 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 the silicone rubber in a dispersed state 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 amount thereof is measured. Just do it. That is, the silicone rubber containing the graphite particles may be heated at a high temperature of 500 ° C. or higher in a nitrogen atmosphere to incinerate and remove the silicone rubber 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. Even when graphite particles having such a high DBP oil absorption amount are used, the addition-curable liquid silicone rubber mixture according to this embodiment has a weight average molecular weight of the component (b) as a cross-linking agent of 5500 or more and 65000 or less. As a result, the component (b) is less likely to be incorporated into the graphite particles, so that curing inhibition is less likely to occur.

(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). When the content of graphite particles is 13% by volume or more, an elastic layer having high thermal conductivity can be easily formed. When 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 it is easy to apply an appropriate stress to the silicone rubber.

Further, 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 as follows for the above-mentioned reason. That is, the content of 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 the addition-curable liquid silicone rubber and the graphite particles in the elastic layer are measured by a thermal weight measuring device (for example, TGA / SDTA851e (trade name), manufactured by METTLER TOLEDO Co., Ltd.). It is possible.

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

First, the above sample placed on an alumina pan was put into a sample chamber, and the temperature of the sample chamber was raised from room temperature (25 ° C.) to 1100 ° C. in a nitrogen atmosphere at a heating rate of 20 ° C./min. Raise the temperature with. Then, the addition-curable liquid silicone rubber (cured product) is thermally decomposed by keeping it constant at 1100 ° C. for 30 minutes under a nitrogen atmosphere. Then, the graphite particles are burned in a high temperature oxygen atmosphere while keeping the temperature at 1100 ° C. From the measured mass reduced at that time, the mass ratios 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 the density, the volumes of the addition-curable liquid silicone rubber (cured product) and the graphite particles can be calculated, and the contents of these in the elastic layer can be calculated.

(Iii) Average particle size The average particle size of the graphite particles is preferably 3 μm or more and 40 μm or less. When the average particle size is 3 μm or more, even if a large amount of graphite particles are added to improve the thermal conductivity, the increase in viscosity of the add-curable liquid silicone rubber before curing can be easily suppressed. Further, when the average particle size is 40 μm or less, it is possible to easily suppress that the rubber surface of the electrophotographic member becomes rough and the image quality becomes uneven with a grainy feeling.
Further, 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 type particle size distribution measuring device (trade name: MT3100II, Microtrac Bell Co., Ltd.). Here, the average particle size of the graphite particles means the so-called median diameter. The median diameter means the particle diameter when the cumulative particle size is 50% in the graph showing the volume average particle size as the cumulative distribution when the particle size distribution is measured.

(2-1-3) Filler The addition-curing liquid silicone rubber mixture may contain titanium oxide, iron oxide, silica or the like as a filler 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 as long as the effects of the present invention are not impaired.

(2-2) Thickness of elastic layer In an 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. Further, 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 transferability 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 shall be 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 front surface can be performed more efficiently. Here, the surface of the electrophotographic member means a surface in contact with the toner. The higher the thermal conductivity, the better, but from the viewpoint of the hardness and strength of the elastic layer, the realistically achievable thermal conductivity is 5.0 W / (m · K) or less. The method for measuring the thermal conductivity will be described later.

(2-4) Tension elastic modulus of elastic layer The tensile elastic modulus of the elastic layer shall be 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 additive-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. .. The method for measuring the tensile elastic modulus will be described later.

(2-5) Method for Forming Elastic Layer 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 No. See Japanese Publication No. 2002-21432). Using these methods, an elastic layer can be formed on the substrate by heating and cross-linking the addition-curable liquid silicone rubber mixture supported on the substrate. It should be noted that ultraviolet rays can also be used when curing the addition-curable liquid silicone rubber mixture.

(3) Substrate (base material)
In the electrophotographic belt, an endless belt-shaped substrate 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 adhesiveness 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, on the inner peripheral surface of the substrate, a protective layer for suppressing wear due to contact with the heater and a sliding layer for improving the slidability with the heater can be provided.

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

(4) Surface layer (release layer) of electrophotographic member
The surface layer as the release layer preferably contains, for example, a fluororesin in order to prevent toner from adhering 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 as long as the moldability and the mold releasability are not impaired.

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 elastic layer is maintained on the elastic layer to maintain the elasticity of the elastic layer. It is possible to easily prevent the surface hardness of (for example, a heating member) from becoming too high.

(4-1) Method for forming the surface layer The method for forming the surface layer is not particularly limited, and for example, the following method can be used. That is, a method of coating a tube-shaped fluororesin on an elastic layer via an adhesive layer, a method in which fine particles of fluororesin are directly or dispersed in a solvent and made into a paint on the surface of the elastic layer. A method of 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 treated with sodium, excimer laser, ammonia, etc. in advance to activate the surface and improve the adhesiveness. Can be done.

FIG. 3 is a schematic view of an example for explaining a step of coating the fluororesin tube 6 as a surface layer on the elastic layer 2 via the adhesive layer 5.

Specifically, an adhesive is applied to the surface of the elastic layer 2 described above to form the adhesive layer 5. The adhesive will be described in detail later. The outer surface of the adhesive layer 5 is coated 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 a vinyl group in the molecular chain, a hydrogen organopolysiloxane, and a platinum compound as a cross-linking 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 one can be used.

It is not necessary when the substrate 1 is a core metal that can retain its shape, but when a thin-walled substrate 1 such as a resin belt or a metal sleeve used for a belt-shaped electrophotographic member is used, it is necessary to use it during processing. In order to prevent deformation, it is desirable to fit the substrate 1 to the core and hold it.

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

After coating, the excess adhesive remaining between the elastic layer 2 and the fluororesin tube 6 can be removed by scraping it out by using a means (not shown). The thickness of the adhesive layer 5 after being squeezed out is preferably 20 μm or less. When 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 it is used as a heating member, it has good followability to the unevenness of paper, and when it is used as a pressure member. In addition, a good fixing image can be easily obtained without narrowing the nip width at the time of 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 thereof are processed to a desired length as necessary, whereby the electrophotographic of the present invention is taken. A member can be obtained.

(4-1-2) Formation of Surface Layer by Fluororesin Coating For the fluororesin coating process for surface layer formation, a method such as electrostatic coating of fluororesin fine particles or spray coating of fluororesin paint is used. Can be done.

When using the electrostatic coating method, first, the inner surface of the mold is electrostatically coated with fluororesin fine particles, and the mold is heated to the melting point of the fluororesin or higher, so that the inner surface of the mold is coated with a thin film of fluororesin. To form. After that, after the inner surface is adhesively treated, the substrate is inserted, the elastic layer material is injected between the substrate and the fluororesin, cured, and then the fluororesin is demolded together. A member can be obtained.

When spray coating is used, fluororesin paint is used. The fluororesin paint forms a so-called dispersion liquid in which fine particles of the fluororesin are dispersed in a solvent by a surfactant or the like. Fluororesin dispersion liquids are also commercially available and are easily available. This dispersion liquid is supplied to a spray gun and sprayed in the form of a mist by gas pressure such as air. If necessary, a member having an elastic layer bonded with a primer or the like is arranged 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. This makes it possible to uniformly form a coating film of the fluororesin paint on the surface of the elastic layer. 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 by using a heating means such as an electric furnace.

(5) Method for Manufacturing Electrophotographic Member The electrophotographic member according to one aspect of the present invention is on the outer peripheral surface of the substrate, that is, the surface of another layer provided directly on the surface of the substrate or on the surface of the substrate. In addition, a coating film of the addition-curable liquid silicone rubber mixture according to one aspect of the present invention is formed, and the addition-curable liquid silicone rubber in the coating film is cured to form an elastic layer. Can be done. Further, if necessary, it is also possible to have a step of forming a surface layer (release layer) and a sliding layer.

(6) Fixing device A fixing device according to one aspect of the present invention will be specifically described.

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

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

The heater 402 is a horizontally long heater housed and held in a groove formed along the width direction in substantially the center of the lower surface of the film guide member 401. The electrophotographic belt 403 according to one aspect 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 means of the fixing device according to FIG. 4, and the heater 402 is in direct contact with the toner and functions as a heating member for heating the toner. This is a member for heating the toner belt 403. Further, the heater 402 is arranged inside the electrophotographic belt 403 in contact with the (inner peripheral surface) of the (endless belt-shaped) substrate of the electrophotographic belt 403.

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

The heater 402 has, for example, a configuration in which a heat generation resistor is provided on a ceramic substrate. The heater 402 is formed by forming a horizontally long and thin plate-shaped heater substrate 402a made of alumina on the surface side (film sliding surface side) along the longitudinal direction of the heater substrate 402a, and is provided with a linear or strip-shaped Ag /. It has a current-carrying heating element (heating resistor) 402c made of Pd. Further, the heater 402 has a thin glass surface protective layer 402d that covers and protects the energizing heating element 402c. The thermistor (temperature measuring element) 402b is in contact with the back surface side of the heater substrate 402a. The heater 402 can be controlled to maintain a predetermined fixing temperature by a power control means (not shown) including a temperature measuring element 402b after the temperature is rapidly raised by supplying power to the energizing heating element 402c. The fixing temperature is a target temperature on the surface of the heating member (electrophotograph belt), and is appropriately set depending on the printing speed, the paper type, the composition of the heating member, and the toner type. The general fixing temperature is 150 ° C. or higher and 200 ° C. or lower.

The pressurizing rotating body (pressurizing member) 404 is arranged to face the lower surface of the heater 402, and is pressed against the heater 402 via the electrophotographic belt (heating member) 403. The rotating body 404 for pressurization is composed of a substrate 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 an electrophotographic belt 403 by a predetermined pressurizing mechanism (not shown). The elastic layer 404b of the rotating body 404 for pressurization is elastically deformed in response to the pressing force, and a predetermined value required for heating and fixing the unfixed toner image T between the surface of the rotating body 404 for pressurization and the surface of the electrophotographic belt 403. A width nip portion N is formed. The pressing force is appropriately set according to the target paper type, size, toner type, and configuration of the fixing device of the product. Normally, the pressing force is set to about 10 kgf (98N) to 70 kgf (686N). The recording material P as a material to be heated is introduced into the nip portion N, and the recording material P is sandwiched and conveyed to heat the recording material P. The driving force of the driving source M is transmitted to the pressurizing rotating body 404 via a gear (power transmission mechanism) (not shown), and the rotating body 404 is rotationally driven in the counterclockwise direction of the arrow b at a predetermined peripheral speed. The electrophotographic belt 403 rotates in the direction of arrow a in accordance with the rotation of the pressurizing rotating body 404 by rotationally driving the pressurizing rotating body 404 in the counterclockwise direction of arrow b during image formation. ..

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

[Example 1]
(1) Preparation of addition-curable liquid silicone rubber mixture (a) Silicone polymer having unsaturated aliphatic groups at both ends (weight average molecular weight 28,000, kinematic viscosity 1000 mm ² / sec, hereinafter "Vi-1"" (Referred to as) was prepared in 100 parts by mass. This silicone polymer is a silicone polymer in which R ₂ is a vinyl group in Structural Formula 5 and the amount of vinyl groups at both ends is 0.5 mol% in terms of the silicon atomic ratio in Vi-1.

Next, as the component (b), 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”) is weighed in 11.0 parts by mass. And added to Vi-1. Incidentally, the (b) a silicone polymer as the component in the structural formula 6, R ₇ is a methyl group, the amount of active hydrogen groups bonded to silicon atom, a silicon atom ratio in SiH-1 6.0 It is a silicone polymer introduced in mol%.

Further, 0.15 parts by mass of a hydrosilylation catalyst (platinum catalyst: 2.0% by mass solution of platinum carbonylcyclovinyl methylsiloxane complex vinyl methylcyclosiloxane) is added to the mixture of the components (a) and (b). , A base polymer (additional curing type liquid silicone rubber) was obtained by mixing sufficiently.

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, the fixing belt was prepared as follows using the obtained addition-curable liquid silicone rubber mixture.

As a substrate, 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. During a series of manufacturing processes, the endless sleeve (endless sleeve) was handled by inserting a core into the sleeve.

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

The addition-curable liquid silicone rubber mixture was applied to a primer-treated substrate by a ring coating method to a thickness of 450 μm. The endless belt to which the silicone rubber mixture is applied is heated in an electric furnace at 160 ° C. for 1 minute (primary curing), and then 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 in the circumferential direction at a moving speed of 20 mm / sec, ultraviolet rays were applied to the surface of the secondarily cured silicone rubber mixture using an ultraviolet lamp installed at a distance of 10 mm from the surface. Irradiation was performed. A low-pressure mercury ultraviolet lamp (trade name: GLQ500US / 11, manufactured by Toshiba Lighting & Technology Corporation (formerly Harison Toshiba Lighting Corporation)) was used as the ultraviolet lamp, and it was irradiated at 100 ° C for 5 minutes in an atmospheric atmosphere to be elastic. Formed a layer.

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

Next, a fluororesin tube having an inner diameter of 54 mm and a thickness of 40 μm (trade name: KURAFLON-LT, manufactured by Kurabo Industries Ltd.) was laminated on this adhesive. Then, by uniformly handling the belt surface from the top of the fluororesin tube, the excess adhesive was squeezed out from between the elastic layer and the fluororesin tube so as to be sufficiently thin.

The obtained endless belt was heated in an electric furnace set at 200 ° C. for 1 hour to cure the adhesive, and the fluororesin tube (surface layer) was fixed on the elastic layer. Both ends 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 elastic modulus of elastic layer)
First, a primer treatment was performed on the substrate by the same method as the method for producing the fixing belt, and then an elastic layer having a thickness of 450 μm (an elastic layer after secondary curing) 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 formula 2.

Calculation 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, the values of the thermal diffusivity, the constant pressure specific heat, and the true density of the elastic layer in the thickness direction were obtained by the following methods.

・ Thermal diffusivity (α)
The thermal diffusivity in the thickness direction of the elastic layer was measured at room temperature (25 ° C.) using a periodic heating method thermophysical property measuring device (trade name: FTC-1, manufactured by ULVAC Riko Co., Ltd.). Regarding the sample pieces, of the 450 μm elastic layer, the 250 μm portion of the elastic layer excluding 100 μm from the surface layer side and 100 μm from the substrate side was cut into a sample piece having an area of 8 × 12 mm and a thickness of 250 μm, and a total of 5 samples were sampled. Pieces were made. When each sample was measured 5 times in total, the average value of 5 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 calorimetry device (trade name: DSC823e, manufactured by METTLER TOLEDO Co., Ltd.).

Specifically, an aluminum pan was used as the sample pan and the reference pan. First, as a blank measurement, with both pans empty, the temperature was kept at a constant temperature of 15 ° C. for 10 minutes, then the temperature was raised to 215 ° C. at a heating rate of 10 ° C./min, and then the temperature was further increased to 215 ° C. for 10 minutes. The measurement was carried out with a program that keeps the temperature constant. Next, 10 mg of synthetic sapphire, which has a known constant pressure specific heat, was used as a reference substance, and measurements were carried out using the same program. Then, the same amount of 10 mg of the measurement sample as the reference sapphire was cut out from the elastic layer portion, set in a pan for the sample, and the measurement was carried out by the same program. These measurement results were analyzed using the specific heat analysis software provided with the differential scanning calorimeter, the arithmetic mean value of 5 measurements was calculated specific heat at constant pressure (C _p) at 25 ° C.. 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 density meter (trade name: Accupic 1330-01, manufactured by Shimadzu Corporation).

Specifically, ^{a sample cell of 10 cm 3} was used, and the sample was cut out from the elastic layer so as to fill 80% of the cell volume and placed in the sample cell. After measuring the mass of this sample, a cell was set in the measuring part in the apparatus, helium was used as a gas for measurement, and after 10 times of gas replacement, volume measurement was carried out 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) Tension elastic modulus of elastic layer In order to confirm that the elastic layer was sufficiently hardened, the tensile elastic modulus of the elastic layer was measured.

Specifically, the dumbbell shape was cut out from the elastic layer by a punching die, and cut out in a size of 20 mm in length, 4 mm in width, and 300 μm in thickness. Next, the cut-out elastic layer was set in an attachment for measuring the tensile elastic modulus of a dynamic viscoelasticity measuring device (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 attached to a fixing device unit of an electrophotographic image forming apparatus (trade name: imagePress C800, manufactured by Canon Inc.) as a heating member. .. This fixing device unit was attached to the electrophotographic image forming device. 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). It was set so as to be parallel), and 1000 evaluation images were continuously printed. As the evaluation image, an image in which cyan toner and magenta toner were formed on the entire surface of the A4 size paper at a concentration of 100% was used. Then, 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 found in the 1000th image. Further, in 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: Defects due to poor fixing are 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 and damage of the elastic layer are observed.

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

The weight average molecular weight, kinematic viscosity, and silicon atomic specific active hydrogen group amount in the component (SiH) of the silicone polymer (SiH) having an active hydrogen group bonded to silicon in Table 1 are as follows.
SiH-2: (weight average molecular weight: 6000, kinematic viscosity 130 mm ² / sec, silicon atomic ratio active hydrogen group amount: 7.5 mol% introduced).
SiH-3: (weight average molecular weight: 2000, kinematic viscosity 35 mm ² / sec, silicon atomic ratio 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 additive-curable liquid silicone rubber 2b Graphite particles 3 Adhesive layer 4 Surface layer (release layer)
5 Adhesive layer 6 Fluororesin tube 402 Heater 403 Electrograph belt (heating member)
404 Pressurizing rotating body (pressurizing member)

Claims (18)

An electrophotographic member having a substrate and an elastic layer on the substrate.
The elastic layer contains 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 of the elastic layer in the thickness direction 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.
An electrophotographic member characterized by this. The electrophotographic member according to claim 1, wherein the 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 or 2, wherein the average particle size of the graphite particles is 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 any one of claims 1 to 3, wherein the substrate has an endless belt shape, and the elastic layer is located on the outer peripheral surface of the substrate having the endless belt shape. .. The electrophotographic member according to claim 4, wherein the elastic layer has a thickness of 0.1 mm or more and 1.0 mm or less. The electrophotographic member according to claim 4 or 5, further having a surface layer on the outer peripheral surface of the elastic layer. The electrophotographic member according to claim 6, wherein the surface layer has a thickness of 10 μm or more and 100 μm or less. Includes organopolysiloxanes with unsaturated aliphatic groups, organopolysiloxanes with active hydrogen bound to silicon, catalysts, 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 hydrogen bonded to the silicon is 5500 or more and 65000 or less.
An addition-curing liquid silicone rubber mixture characterized by this. 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 average particle size of the graphite particles is 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 hydrogen bonded to silicon has a kinematic viscosity of 130 mm ² / sec or more and 9000 mm ^{2 / sec or less at a temperature of 25 ° C.} Liquid silicone rubber mixture. Claims 8 to 12 that the amount of active hydrogen bonded to the silicon in the organopolysiloxane having the active hydrogen bonded to the 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 20000 to 80000. 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 of 1000 to 30,000 mm ^{2 / sec at a temperature of 25 ° C.} A method for manufacturing an electrophotographic member having a substrate and an elastic layer on the substrate.
For electrophotographic use, which comprises a step of curing a 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 parts. A fixing device having a heating member and a pressurizing member arranged so as to face the heating member.
The fixing device according to any one of claims 1 to 7, wherein the heating member is an electrophotographic member. The fixing device according to claim 17, wherein the heating member is the electrophotographic member according to claim 4, and a heater is arranged in contact with the inner peripheral surface of the substrate.

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