JP2937622B2 - Fixing roll - Google Patents

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 an apparatus utilizing an electrophotographic process such as an electrophotographic copying machine or an electrophotographic printer, and more particularly to a fixing roll capable of sufficiently securing a nip width and a compression set. The present invention relates to a fixing roll having a small number of fixing rolls, which can sufficiently cope 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 a toner image transferred from the surface of a photoreceptor to the copy paper on the copy paper. . As a method of fixing this toner image, a copy sheet is passed between a heated fixing roll and a pressure roll which are rotating while being pressed against each other,
There is known a method of fixing a toner image on a copy paper by heat fusion. This method has been widely adopted at present because of the simplicity of the apparatus, the security, and the fact that it is easy to cope with the high-speed copying. As this fixing roll, a roll provided with an elastic layer on the surface of a cored bar is often used, and as a material constituting the elastic layer, silicone rubber is used in terms of heat resistance, elastic properties, release properties, and the like. Often used.

[0003] 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 period of time. R & D is ongoing over Various measures have been devised for the fixing roll, and 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 a technique disclosed in Japanese Patent Application Laid-Open No. 61-32081. Like
There is known a technique in which a fluororesin layer is used as the outermost layer of a fixing roll to extend the life of the roll and improve the quality of a fixed image obtained.

[0004] Such a fixing roll has achieved some success, but a soft silicone rubber, for example, an elastic layer using a material having a hardness of 20 ° (JIS A) or less, is further coated with a fluorine resin. When attempting to form a coating layer, the present applicant has found that the hardness of the fluorine-based resin coating layer on the surface does not necessarily decrease even though a material having a low hardness is used for the elastic layer. Therefore, when an extremely soft silicone rubber having a hardness of, for example, about 8 ° (JIS A) is used as the elastic layer of the fixing roll,
The strength was weak, the compression set was large, and it was difficult to obtain a practical fixing roll.

[0005]

An object of the present invention is to provide 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. New proposals for manufacturing rolls were awaited. Therefore, an object of the present invention is to provide a fixing roll having a silicone elastic layer on the surface of a core metal and a fluororesin coating layer on the outermost surface, 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 can sufficiently cope with high-speed copying.

[0006]

Means for Solving the Problems The inventors of the present invention have made intensive studies to develop the useful fixing roll, and have finally arrived at the present invention.
The present invention proposes a fixing roll characterized in that a silicone rubber having a specific hardness and a specific viscoelasticity is selectively used as a silicone rubber layer which is a layer below a fluoropolymer surface layer of the fixing roll. . That is, the present invention relates to a fixing roll having a silicone rubber layer on the core metal surface and further having a fluororesin coating layer on the outermost layer, wherein the hardness of the silicone rubber layer is 8 to 20 ° (JIS A), 25
The elastic modulus at a frequency of 10 Hz at 2.0 ° C is 2.0 × 10 ⁷ d
yn / cm ² and a dielectric loss tangent (tan δ) of 5.0 ×
An object of the present invention is to provide a fixing roll characterized by being 10 ⁻² or less.

In the present invention, as the silicone rubber layer of the fixing roll, a very soft one having a 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 ° C
Nip width can be sufficiently secured 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. It was possible to provide a truly revolutionary fixing roll that has a small compression set and can withstand paper passing.

[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 within the range of 10 to 15 ° (JIS A). If the hardness is 20 ° or more, a sufficient nip width required in the present invention cannot be secured. On the other hand, if the hardness is 8 ° or less, there is a disadvantage that the strength required for the fixing roll cannot be obtained.

The silicone rubber layer of the present invention further comprises
The elastic modulus at a frequency of 10 Hz at 5 ° C. is 2.0 × 10
⁷ dyn / cm ² or less and dielectric loss tangent (tan δ) of 5.0
What is less than × 10 ^-2 is 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 elasticity is correlated with the hardness of the silicone rubber layer. There is a disadvantage 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 an average of at least three alkenyl groups in one molecule;
A hydrogen polysiloxane having 2 to 4 hydrogen atoms directly bonded to silicon atoms in one molecule, and (c) a silicone rubber prepared by reacting a mixture of inorganic fillers in the presence of a catalyst. You.

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

Embedded image (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 second component, hydrogenpolysiloxane, is a compound known per se, which acts as a cross-linking agent for reacting with the 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 bonded directly to a silicon atom is required. It must be an organohydrogenpolysiloxane having 2 to 4 atoms in one molecule. One molecule contains one hydrogen atom directly bonded to a silicon atom.
If individual pieces are used, it is not possible to obtain a cured product as an elastic body having a sufficient function required in the present invention.
Also, when the number of hydrogen atoms bonded to the silicon atoms is 4 or more, the viscoelastic properties required in the present invention cannot be obtained. Specific examples of the organohydrogenpolysiloxane include the following compounds.

Embedded image (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. Of course, it is good. The hydrogenpolysiloxane is used in an amount of 0.5 to 3.5, preferably 1 to 2, hydrogen atoms directly bonded to silicon atoms per one alkenyl group bonded to silicon atoms in component (a). It is an amount of 0.0.

As the catalyst, any known catalyst that participates in the reaction between the organopolysiloxane and the hydrogenpolysiloxane can be used. As a suitable catalyst, platinum or a platinum group compound can be exemplified. Further, specifically, alcohol-modified chloroplatinic acid, a complex of chloroplatinic acid and an olefin, or a complex of platinum and vinylsiloxane is exemplified. The amount of the catalyst to be added may be appropriately adjusted so as to obtain a desired curing rate. Specifically, the amount of platinum is 5% based on the total amount of the components (a) and (b).
To 500 ppm, preferably 10 to 200 pp
m.

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

If necessary, additives known per se can be added and compounded as long as the effects of the present invention are not impaired. Examples of the compounding agent include a release agent, conductive carbon, a coloring agent, a reaction control agent, and a heat resistance improving agent, for example, iron oxide or cerium oxide. Silicone oil is known as the release agent, acetylene alcohols and the like are used as a 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 cured by heating. Then, a thin tube made of a fluorine-based resin is placed on the surface of the cured rubber layer, and heated to form a fluorine-based resin coating layer on the surface of the cured layer. Alternatively,
Prepare a cylindrical mold, fix the 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 and cure Can be manufactured.

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 is heated for 3 minutes to 1 hour, preferably for 10 to 20 minutes. If necessary, post-curing can be performed at a temperature of 150 to 200 ° C. for 30 minutes to 4 hours. The thickness of the silicone rubber layer is appropriately selected. For example, a layer having a thickness of 0.2 to 7.0 mm is used.

The fluoropolymer which is a raw material of the surface layer may be any fluoropolymer which is used as a fixing roll and is known before the present application. Specifically, preferred fluoropolymers include tetrafluoroethylene homopolymers or copolymers, chlorotrifluoroethylene homopolymers or copolymers, tetrafluoroethylene homopolymers or copolymers, vinyl fluoride homopolymers or copolymers, and the like. There is a homopolymer or copolymer of vinylidene fluoride, and examples of the comonomer composing the copolymer include those represented by the following general formula in addition to the above-mentioned monomer. _{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
And m is 1 to 5) Of these, copolymers containing monomers such as tetrafluoroethylene and perfluoroalkoxyvinyl 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]

The fixing roll of the present invention has a fluorine resin coating layer formed on the surface thereof, so that the characteristics of the fluorine resin coating layer can be sufficiently exhibited and the low hardness of the silicone rubber layer can be obtained. Is a role that reflects
This makes it possible to provide a fixing roll having excellent characteristics. That is, in addition to securing a sufficient nip width, small compression set, heat resistance,
Since it has excellent durability and releasability, it can sufficiently cope with high temperature and high speed of the fixing section of the copying machine, and can provide a fixing roll having a long life.

[0020]

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

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

Embedded image 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 sheet having a thickness of 2 mm
It was prepared by press molding under molding conditions of 20 ° C./10 minutes, and then subjected to secondary vulcanization at 200 ° C. for 4 hours. Next, the hardness of the cured product was measured according to JIS K6301. Further, the modulus of elasticity and the dielectric loss tangent (tan δ) were measured using a DVE spectrum manufactured by Rheology. On the other hand, the core metal having been subjected to the degreasing treatment and the primer was inserted into the same cylindrical mold, and a PFA fluororesin tube having a thickness of 50 μm, which was at the inner diameter of the mold, was attached to the inner surface of the mold. The above composition was poured into a mold, and 10
It was left at 0 ° C. for 30 minutes to cure. Then, it is extracted from the mold and subjected to secondary vulcanization at 200 ° C. for 4 hours to obtain an outer diameter of 40 ° C.
A silicone rubber roller having a PFA tube having an outer diameter of 5 mm and a rubber thickness of 5 mm was manufactured. The surface hardness of the rubber roller was measured using an Asker-C hardness tester. Table 1 shows the measurement results.

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

Embedded image Parts by weight, and methyl hydrogen polysiloxane represented by the following formula as the component (b):

Embedded image A sample was prepared in the same mixing ratio and working method as in Example 1 except that 0.7 parts by weight was used. Using this composition, a sheet and a roll were prepared in the same manner as in Example 1,
The hardness, elastic modulus and dielectric loss tangent (tan δ) were measured.
Table 1 shows the measurement results.

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

Embedded image Parts by weight, and methyl hydrogen polysiloxane represented by the following formula as the component (b):

Embedded image A sample was prepared in 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 were prepared in the same manner as in Example 1,
The hardness, elastic modulus and dielectric loss tangent (tan δ) were measured.
Table 1 shows the obtained results. Table 1 shows the measurement results.

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

Embedded image Parts by weight, and methyl hydrogen polysiloxane represented by the following formula as the component (b):

Embedded image A sample was prepared in the same mixing ratio and working method as in Example 1 except that the amount was 0.5 parts by weight. Using this composition, a sheet and a roll were prepared in the same manner as in Example 1,
The hardness, elastic modulus and dielectric loss tangent (tan δ) were measured.
Table 1 shows the obtained results. Table 1 shows the measurement results.

[0024] * In the column of the fixed image quality, "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 spectrumr) manufactured by Rheology. Specifically, the frequency is changed from 1 Hz to 10 at an initial load of 200 g in an atmosphere of 25 ± 1 ° C.
0 Hz, measured in compression mode, frequency 10
The value of Hz was determined.

Claims (3)

(57) [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 not more than 5.0 × 10 ^-2 . 2. The silicone rubber layer comprises an organopolysiloxane (a) having an average of at least three alkenyl groups in one molecule, and two to four hydrogen atoms directly bonded to silicon atoms in one molecule. The fixing roll according to claim 1, wherein the fixing roll is obtained from a mixture of an organohydrogenpolysiloxane (b) and an inorganic filler (c). 3. The fixing roll according to claim 1, wherein the fluororesin coating layer comprises a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer.