JPH06167900A - Fixing roller - Google Patents

Abstract

PURPOSE:To provide the fixing roller which is a fixing roller having a fluororesin coating layer and a silicone rubber elastic material layer and with which a sufficient nip width can be assured and which is small in permanent compression set and can deal sufficiently with high-speed copying as well. CONSTITUTION:The silicone rubber having 8 to 20 deg. (JISA) hardness, <2.0X10<7> dyn/cm<2> modulus of elasticity at 10Hz frequency at 25 deg.C and >=5.0X10<-2> dielectric tangent (tandelta) is used as the elastic material layer of the fixing roll. The silicone rubber is obtd. from a mixture composed of organo-polysiloxane having at least average 3 pieces of alkenyl groups in one molecule (a), organo-hydrogen polysiloxane having 2 to 4 pieces of hydrogen atoms directly coupled to a silicon atom in one molecule (b) and an inorg. filler (c).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing roll used in a device utilizing an electrophotographic process such as an electrophotographic copying machine or an electrophotographic printer, and in particular, a sufficient nip width can be secured and a compression set. The present invention relates to a fixing roll that has a small amount of heat and is sufficiently compatible with high-speed copying.

[0002]

2. Description of the Related Art In an apparatus utilizing an electrophotographic process such as an electrophotographic copying machine or an electrophotographic printer, it is necessary to fix the toner image transferred from the surface of the photoconductor to the copying paper to the copying paper. . As a method of fixing the toner image, a copy paper is passed between a heated fixing roll and a pressure roll which are rotated in pressure contact with each other,
A method is known in which a toner image on a copy paper is thermally fused and fixed. This method has been widely adopted at present because of the simplicity of the device, safety, and easy handling of high-speed copying. As this fixing roll, a roll having an elastic layer on the surface of a core bar is often used, and as a material for forming the elastic layer, silicone rubber is used in terms of heat resistance, elastic properties or releasability. It is often used.

By the way, there is an increasing demand for a copying machine capable of obtaining a large number of copies having high-quality images in a short time, and it is widely used for developing a photoconductor, improving a developing device and a transfer device. Research and development is underway. Various improvements have been made to the fixing roll, for example, a technique for improving the nip width of the fixing roll by using a soft material as the elastic layer of the fixing roll, and the technique disclosed in JP-A-61-32081. Like
A technique is known in which a fluorine resin layer is used as the outermost layer of the fixing roll to extend the life of the roll and improve the quality of the obtained fixed image.

Such a fixing roll has achieved some results, but on a flexible silicone rubber, for example, an elastic layer made of a material having a hardness of 20 ° (JIS A) or less, a fluorine resin is further added. The present applicant has found that, when an attempt is made to form a coating layer, the hardness of the fluororesin coating layer on the surface does not necessarily decrease even though a material having low hardness is used for the elastic layer. Therefore, if an extremely soft silicone rubber having a hardness of about 8 ° (JIS A) is used as the elastic layer of the fixing roll,
It was difficult to obtain a practical fixing roll because the strength was low and the compression set was large.

[0005]

A fixing roll in which a silicone rubber having a low hardness is used as an elastic layer and a fluorine resin coating layer is provided on the surface of the elastic layer, and the nip width is sufficiently secured. A new proposal to manufacture rolls was awaited. Therefore, an object of the present invention is to provide a fixing roll having a silicone elastic layer on the surface of a cored bar and a fluorine resin coating layer on the outermost side, and having a low hardness. Another object of the present invention is to provide a fixing roll that can secure a nip width, has a small compression set, and is sufficiently compatible with high-speed copying.

[0006]

The inventors of the present invention have finally arrived at the present invention as a result of earnest research to develop the useful fixing roll, and in order to achieve the above-mentioned object,
The present invention proposes a fixing roll characterized by selectively using a silicone rubber having a specific hardness and a specific viscoelasticity as a silicone rubber layer which is a layer below the fluoropolymer surface layer of the fixing roll. . That is, according to the present invention, in a fixing roll having a silicone rubber layer on the surface of a core metal and a fluororesin coating layer on the outermost layer, the hardness of the silicone rubber layer is 8 to 20 ° (JIS A), 25.
Elastic modulus at a frequency of 10 Hz at 2.0 x 10 ⁷ d
Less than yn / cm ² and dielectric loss tangent (tan δ) is 5.0 ×
The present invention provides a fixing roll characterized by being 10 ^-2 or less.

In the present invention, as the silicone rubber layer of the fixing roll, one having a very soft hardness of 8 to 20 ° (JIS A) is selected, and further attention is paid to the dynamic viscoelasticity of the silicone rubber, Frequency 10Hz at 25 ℃
By selecting and using an elastic modulus of less than 2.0 × 10 ⁷ dyn / cm ² and a dielectric loss tangent (tan δ) of 5.0 × 10 ⁻² or less, a sufficient nip width can be secured, It was possible to provide a truly epoch-making fixing roll which has a small compression set and can withstand the passage of paper.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be specifically described below. The hardness of the silicone rubber layer of the present invention is 8 to 20 °.
(JIS A), more preferably 10 to 15 ° (JIS A). When the hardness is 20 ° or more, it is not possible to secure a sufficient nip width required in the present invention. Further, when the hardness is 8 ° or less, there is a drawback that the strength required for the fixing roll cannot be obtained.

The silicone rubber layer of the present invention further comprises 2
Elasticity of 2.0 × 10 at a frequency of 10 Hz at 5 ° C.
⁷ dyn / cm ² or less and dielectric loss tangent (tan δ) of 5.0
Those having a ^{density of} 10 ⁻² or less are used. When the elastic modulus at a frequency of 10 Hz at 25 ° C. is 2.0 × 10 ⁷ dyn / cm ² or more and the dielectric loss tangent (tan δ) is 5.0 × 10 ⁻² or more, the silicone rubber layer is correlated with the hardness. There is an inconvenience that the surface hardness of the roller does not decrease.

The silicone rubber layer used in the fixing roll of the present invention comprises (a) an organopolysiloxane having at least 3 alkenyl groups on average in one molecule, (b)
Hydrogen polysiloxane having 2 to 4 hydrogen atoms directly bonded to silicon atoms in one molecule, (c) Silicone rubber prepared by reacting a mixture of inorganic fillers in the presence of a catalyst It

The above-mentioned specific organopolysiloxane is a known compound, which has an average of at least 3 alkenyl groups in one molecule and is composed of a main chain composed of SiO bonds and an organic group containing an alkenyl group. Is used. Examples of the alkenyl group include a vinyl group, an allyl group, and a hexenyl group, with a vinyl group being particularly preferred.
The organic groups other than the alkenyl group include methyl group, ethyl group, propyl group, phenyl group, 3,3,3-
A substituted or unsubstituted monovalent hydrocarbon group such as a trifluoropropyl group may be mentioned. CS The organopolysiloxane is 100 to 10 at room temperature.
It has a viscosity of 10,000 CS, preferably 500 to 1 × 10 ⁵ CS. Specific examples of these organopolysiloxanes include the following.

[Chemical 1] (However, in the above formula, a, b and c are positive integers, and d is a positive integer of 3 or more.) The organopolysiloxane may be a single compound or a mixture of two or more compounds. Is natural. Further, even a partially branched structure can be used as long as the effects of the present invention are not impaired.

The above-mentioned second component, hydrogen polysiloxane, is a compound known per se, which acts as a cross-linking agent by reacting with the constituent component (a) to obtain a silicone elastomer. The compound used in the present invention may be linear, branched, or cyclic, but in order to achieve the object of the present invention, hydrogen directly bonded to a silicon atom is used. It is necessary that the organohydrogenpolysiloxane has 2 to 4 atoms in one molecule. 1 hydrogen atom directly bonded to silicon atom in one molecule
If one is used, a cured product as an elastic body having a sufficient function required in the present invention cannot be obtained.
Further, if the number of hydrogen atoms bonded to the silicon atom is 4 or more, the viscoelastic property required in the present invention cannot be obtained. The following compounds may be mentioned as specific examples of the organohydrogenpolysiloxane.

[Chemical 2] (However, in the above formula, l and m are positive integers, and n is a positive integer of 0 or 1, 2.) The organohydrogenpolysiloxane may be a single compound or a mixture of two or more compounds. Of course it is good. The hydrogen polysiloxane is used in an amount of 0.5 to 3.5, preferably 1 to 2 hydrogen atoms directly bonded to the silicon atom per one alkenyl group bonded to the silicon atom in the component (a). It is an amount of 0.0.

As the catalyst, any known catalyst can be used as long as it is a known catalyst involved in the reaction between the organopolysiloxane and the hydrogen polysiloxane. Platinum or a platinum group compound can be illustrated as a suitable catalyst. Further, specific examples thereof include alcohol-modified chloroplatinic acid, a complex of chloroplatinic acid and an olefin, or a complex of platinum and vinylsiloxane. The amount of this catalyst added may be appropriately adjusted so that a desired curing rate can be obtained. Specifically, the amount as platinum is 5% with respect to the total amount of the components (a) and (b).
To 500 ppm, preferably 10 to 200 pp
It can be in the range of m.

The inorganic filler is not particularly limited as long as it is used in a silicone rubber compound. Specific examples thereof include fumed silica, precipitated silica, diatomaceous earth, and quartz powder. The compounding amount is in the range of 10 to 80 parts by weight with respect to 100 parts by weight of the component (a).

If necessary, compounding agents known per se can be added and blended as long as the effects of the present invention are not impaired. Examples of the compounding agent include a release agent, conductive carbon, a colorant, a reaction control agent, and a heat resistance improver such as iron oxide or cerium oxide. Silicone oil is known as the release agent, acetylene alcohols and the like are used as the reaction control agent, and examples of the heat resistance improver include iron oxide and cerium oxide.

The fixing roll of the present invention can be manufactured by utilizing a known method. Specifically, a layer made of a mixture of the above compounds is formed on the surface of the core metal,
The mixture layer is heat-cured. Then, a thin tube made of fluororesin is placed on the surface of the cured rubber layer and heated to form a fluororesin coating layer on the surface of the cured layer. Alternatively,
Prepare a cylindrical mold, fix a core metal in the center of the mold, fix the tube inside the mold, inject the mixture between the core metal and the tube, and heat cure Can be manufactured by.

The conditions for heating and curing the mixture layer are as follows. The heating temperature of the mixture layer is 100 to 170 ° C., preferably 120 to 150 ° C., and the mixture layer is heated for 3 minutes to 1 hour, preferably 10 to 20 minutes. If necessary, post-curing can be carried out at a temperature of 150 to 200 ° C. for 30 minutes to 4 hours. The thickness of this silicone rubber layer is appropriately selected, but for example, one having a thickness of 0.2 to 7.0 mm is used.

The fluorine-based polymer as the raw material for the surface layer may be any fluorine-based polymer known as a fixing roll and known before this application. Specifically, preferred fluoropolymers include homopolymers or copolymers of tetrafluoroethylene, homopolymers or copolymers of chlorotrifluoroethylene, homopolymers or copolymers of tetrafluoroethylene, homopolymers or copolymers of vinyl fluoride, or There are vinylidene fluoride homopolymers and copolymers, and examples of the comonomer forming the copolymer include, in addition to the above-mentioned monomers, those represented by the following general formula. _{X 1 (F 2) n CX} 2 = CX 3 X 4 X 1 (CF 2) n OCX 2 = CX 3 X 4 X 1 (CF 2) n O (CF 2 CF 2 O) m CX 2 = CX 3 X
₄ (wherein X ₁ , X ₂ , X ₃ , and X ₄ are F or H, and n is 1
Among these, copolymers containing monomers such as tetrafluoroethylene and perfluoroalkoxy vinyl ether are particularly useful. The thickness of the surface layer of this fluoropolymer is 20 to
200 μm, especially 30 to 120 μm is preferred.

[0019]

EFFECT OF THE INVENTION Since the fixing roll of the present invention has the fluororesin coating layer formed on the surface, the characteristics of the fluororesin coating layer can be fully exhibited and the hardness of the silicone rubber layer is low. Is a role that reflects
It is possible to provide a fixing roll having excellent characteristics. That is, the nip width can be sufficiently secured, the compression set is small, and the heat resistance,
Since it is excellent in durability and releasability, it was possible to provide a fixing roll which can sufficiently cope with high temperature and high speed of the fixing portion of the copying machine and has a long life.

[0020]

The present invention will be described in more detail with reference to the following examples, but it goes without saying that the present invention is not limited to these examples. Example 1 As component (a), a silicone oil having a viscosity of 15000 CS represented by the following formula

[Chemical 3] To 100 parts by weight, 4 parts by weight of fumed silica (trade name R-972: manufactured by Tegusa Co.) having a surface area of 130 m ² / g surface-treated with a dimethylsilyl group, and 15 parts by weight of quartz powder (average particle size 2 μ) Then, 2 parts by weight of iron oxide was added and kneaded homogeneously with a gate mixer, then 0.3 parts by weight of a 2% solution of chloroplatinic acid in 2-ethylhexanol and 0.2 parts by weight of ethynylcyclohexanol as a reaction control agent. In addition, finally expressed by the following formula

[Chemical 4] 10 parts by weight of methyl hydrogen polysiloxane was added and mixed homogeneously to prepare a compound by a conventional method. Using this sample, a 2 mm thick sheet was
It was prepared by a press molding method under molding conditions of 20 ° C./10 minutes, and then secondary vulcanization was performed at 200 ° C. for 4 hours. Next, the hardness of this cured product was measured according to JIS K6301. Further, the elastic modulus and the dielectric loss tangent (tan δ) were measured using a DVE spectrumr manufactured by Rheology. On the other hand, a core metal coated with a degreasing treatment and a primer was inserted into the same cylindrical mold, and a PFA fluororesin tube having a thickness of 50 μm, which was in the mold inner diameter, was attached to the inner surface of the mold. Inject the above composition into the mold and
It was left to cure at 0 ° C. for 30 minutes. After that, it was taken out of the mold and subjected to secondary vulcanization at 200 ° C for 4 hours to give an outer diameter of 40
mm, and a rubber thickness of 5 mm was used to produce a silicone rubber roller having a PFA tube as the outermost layer. The surface hardness of this rubber roller was measured using an Asuka-C hardness meter. The measurement results are shown in Table 1.

Example 2 As component (a), a silicone oil 100 having a viscosity of 1 × 10 ⁵ CS represented by the following formula:

[Chemical 5] Parts by weight, and the methylhydrogenpolysiloxa represented by the following formula as the component (b)

[Chemical 6] A sample was prepared with the same mixing ratio and working method as in Example 1 except that the amount was 0.7 parts by weight. Using this composition, a sheet and a roll are prepared in the same manner as in Example 1,
Hardness, elastic modulus and dielectric loss tangent (tan δ) were measured.
The measurement results are shown in Table 1.

Comparative Example 1 Silicone oil 100 having a viscosity of 100,000 CS represented by the following formula as component (a):

[Chemical 7] Parts by weight, and the methylhydrogenpolysiloxa represented by the following formula as the component (b)

[Chemical 8] A sample was prepared with the same mixing ratio and working method as in Example 1, except that the amount was 0.74 parts by weight. Using this composition, a sheet and a roll are prepared in the same manner as in Example 1,
Hardness, elastic modulus and dielectric loss tangent (tan δ) were measured.
The results obtained are shown in Table 1. The measurement results are shown in Table 1.

Comparative Example 2 Silicone oil 100 having a viscosity of 100,000 CS represented by the following formula as component (a)

[Chemical 9] Parts by weight, and the methylhydrogenpolysiloxa represented by the following formula as the component (b)

[Chemical 10] A sample was prepared with the same mixing ratio and working method as in Example 1, except that the amount was 0.5 part by weight. Using this composition, a sheet and a roll are prepared in the same manner as in Example 1,
Hardness, elastic modulus and dielectric loss tangent (tan δ) were measured.
The results obtained are shown in Table 1. The measurement results are shown in Table 1.

[0024] * In the fixed image quality column, "A" indicates that the quality of the fixed image is excellent, and "B" indicates that the quality of the fixed image is not excellent. * The elastic modulus and the dielectric loss tangent (tan δ) were measured using DYNAMIC VISCO-ELASTIC ANALYZER (DVE Spectra) manufactured by Rheology. Specifically, in an atmosphere of 25 ± 1 ° C. and an initial load of 200 g, the frequency is from 1 Hz to 10 Hz.
Change to 0Hz, measure in compression mode, frequency 10
The value of Hz was obtained.

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[Procedure amendment]

[Submission date] May 26, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

The above-mentioned specific organopolysiloxane is a known compound, which has an average of at least 3 alkenyl groups in one molecule and is composed of a main chain composed of SiO bonds and an organic group containing an alkenyl group. Is used. Examples of the alkenyl group include a vinyl group, an allyl group, and a hexenyl group, with a vinyl group being particularly preferred.
The organic groups other than the alkenyl group include methyl group, ethyl group, propyl group, phenyl group, 3,3,3-
A substituted or unsubstituted monovalent hydrocarbon group such as a trifluoropropyl group may be mentioned. The organopolysiloxane has a viscosity of 100 to 100,000 CS, preferably 500 to 1 × 10 ⁵ CS at room temperature. Specific examples of these organopolysiloxanes include the following.

[Chemical 1] (However, in the above formula, a, b and c are positive integers, and d is a positive integer of 3 or more.) The organopolysiloxane may be a single compound or a mixture of two or more compounds. Is natural. Further, even a partially branched structure can be used as long as the effects of the present invention are not impaired.

Claims (3)

[Claims] 1. A fixing roll having a silicone rubber layer on the surface of a core metal and a fluororesin coating layer on the outermost layer, wherein the hardness of the silicone rubber layer is 8 to 20 ° (JIS
A), the elastic modulus at a frequency of 10 Hz at 25 ° C. is 2.
Less than 0 × 10 ⁷ dyn / cm ² and dielectric loss tangent (tan δ)
Is less than 5.0 × 10 ^-2 , and a fixing roll. 2. The organopolysiloxane (a), wherein the silicone rubber layer has at least 3 alkenyl groups on average in one molecule, and 2 to 4 hydrogen atoms directly bonded to silicon atoms in one molecule. 2. The fixing roll according to claim 1, which is obtained from a mixture of the organohydrogenpolysiloxane (b) and the inorganic filler (c). 3. The fixing roll according to claim 1, wherein the fluororesin coating layer is made of a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer.