JPH0643118B2 - Rubber surface material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a friction charging blade for a developing machine in an electrostatic electrophotographic apparatus such as an electrostatic copying machine (hereinafter referred to as PPC) or a laser printer (hereinafter referred to as LBP). The present invention relates to a rubber-like surface layer material useful as a fixing roller, a fixing roll, and the like, and particularly to a rubber-like surface layer material having a small coefficient of friction, no tackiness, and excellent stain resistance.

(Prior Art) Rubber materials such as silicone rubber, fluororubber, and urethane rubber have come to be used as materials for friction charging blades and fixing rolls of electrostatic electrophotographic apparatuses.

In this electrostatic electrophotographic process, an electrostatic latent image is developed with a charged powder called toner to visualize it. (1) A photosensitive drum [Se system, OPC (organic photoconductive material) is formed by a corona discharger for charging. Body) system, etc.] a charging process for charging a uniform (+) charge on (2) an exposure lamp in the case of PPC,
LB by analog optical system such as lens and mirror
In the case of P, an exposure process of forming an electrostatic latent image of (+) charge on the photosensitive drum according to the original pattern by a laser scanning optical system such as a polygon mirror; (3)
A magnet roll (hereinafter referred to as a developing roll) to which a thin layer of charged toner is attached to (-) is brought into contact with the photosensitive drum, and the toner is transferred onto the electrostatic latent image of (+) charge to form a toner pattern. Developing process: (4) A (+) charge is supplied from the back surface of the paper by the transfer corona discharger to transfer the toner pattern on the photosensitive drum to plain paper for transfer (hereinafter referred to as PPC paper), and then from the photosensitive drum. Transfer process for peeling PPC paper; (5) P with toner pattern attached
A fixing process in which the PC paper is passed through a fixing roll composed of a heat roll and a backup roll, and the toner is press-fitted and fixed into the paper fiber structure by thermocompression bonding.

The PPC developing method includes a one-component developing method in which a non-magnetic toner is used alone, and a two-component developing method in which a magnetic particle carrier such as iron powder or ferrite powder having a particle diameter of 10 to 100 μm is mixed with a non-magnetic toner. In the past, the latter was the mainstream in the past, but the former has advantages such as a simple structure of the developing machine, compact size, no toner concentration control, and no stirring mechanism. It is being adopted for low-speed PPC.

This non-magnetic toner includes a thermoplastic resin binder (copolymerized polyester, polyethylene, styrene-acrylonitrile copolymerized resin, etc.), a colorant (carbon black in the case of black toner), a charge control agent (electron-accepting organic compound, etc.), Particle diameter of 5 to 25 μm and softening point of 70 to 8 consisting of other additives (hydrophobic silica, metal salt of fatty acid, etc.)
The particles are amorphous or spherical particles at 0 ° C., and in the two-component developing system, the above-mentioned magnetic particle carrier is mixed and toner coated on the photosensitive drum by a magnetic brush developing machine or the like.

The charging friction blade is used for the one-component developing method using the above-mentioned non-magnetic toner, and the toner is charged with a (-) electric charge by a simple mechanism of pressing this blade against the developing roll so that the surface of the developing roll has a constant thickness. To form the toner layer.

Now, the process will be described in detail with reference to the accompanying drawings. As shown in FIG. 1, the developing device 1 includes a hopper-shaped container 2, a developing roll 3, a friction charging blade 4, and a recovering blade 5. By the rotation of the developing roller 3 having fine irregularities on the surface, the toner particle group 6
Reaches under the pressure of the blade 4, where it is sheared and a uniform thin toner layer is formed. During this thinning process, the toner particles are subjected to frictional shearing of the blade and roll to acquire a (-) electric charge. The thin layer of charged toner particles adheres to the surface of the developing roll and reaches the transfer position of the photosensitive drum 7. As shown in FIG. 2, the charging friction blade is formed by integrally molding a rubber sheet 9 having a constant thickness on one surface of a spring steel strip 8 made of stainless steel or the like. As described above, it is set in the developing device and used.

(Problems to be solved by the invention) When a friction charging blade made of a rubber material having excellent wear resistance is used, the toner adheres to the contact surface between the blade and the developing roll and inhibits layer formation. Among them, silicone rubber having the lowest wear resistance is used. (By looking at the abrasion resistance in the JIS rubber material performance comparison table, natural rubber, IR, SB
R, BR, CR, EVA, CSM, chlorinated polyethylene, urethane rubber, fluororubber, etc. are considered “good”, NBR, IIR, EPDM, epichlorohydrin rubber, acrylic rubber, etc. are also “OK”. The silicone rubber is mentioned as the material. According to the results of the experiments conducted by the present inventors, rubbers other than silicone rubber are also unsuitable as triboelectric charging blades because they hinder layer formation due to toner sticking. In short, the required characteristic of this blade material is that the formation of the tobar layer causes abrasion and always exposes a new rubber surface.

However, there is a problem here concerning the middle / high speed PPC. That is, in a low speed PPC such as a personal copying machine, the A4 copy speed per minute is 5 to 15 sheets,
20 or more medium-speed PPCs and 50 or more high-speed PPCs are required, and the current silicone rubber triboelectrification blades cause rapid wear and frequent replacement and complicated maintenance when used for medium and high-speed PPCs. It's a problem.

On the other hand, in the fixing process (FIG. 3), the heat roll 11 is required to have high heat resistance and good releasability from the toner. Tetrafluoroethylene (PTF
A coating layer 14 of fluororesin such as E) is provided, or a tube 14 made of fluororubber such as vinylidene fluoride / propylene hexafluoride copolymer is coated. Further, the backup roll 15 has heat resistance, is excellent in compression recovery in this high temperature region, and is required to have releasability from toner and paper feeding property (paper does not wind around the roll). Used. In particular, from the viewpoint of paper feeding property, it is better that the entire roll system is flexible and the surface layer is hard, so that the rubber hardness (JIS-A) is 50 to 70 ° Hs on the surface of the silicone rubber sponge core.
The one provided with the silicone rubber layer is used. However, in this backup roll, first, a silicone rubber sponge 17 is integrally molded on a metal core (rod or cylinder) 16 by a mold foaming press molding method, and then the surface is polished, and a cylindrical casting metal for making this into a final roll shape. A complicated method in which the mold is set at the center of the mold, normal temperature or low temperature vulcanizing type silicone rubber (hereinafter referred to as RTV silicone rubber) 18 is injected from the end of the mold in the axial direction, and the mold is pulled out after curing. Since it is manufactured by the method described above, the cost is high, and since silicone rubber is not as good in toner releasability as fluororesin or fluororubber, it has the drawback of being easily soiled. On the other hand, a roll made of fluororubber alone has a high material unit price and also has a rubber hardness (JIS-
Since A) is a hard material having a temperature of 60 ° Hs or more, it has a drawback of poor paper feeding property.

(Means for Solving the Problems) The present invention relates to a rubber-like surface layer material useful as a rubber roll or a rubber blade in which such disadvantages are solved, in which a rubber substrate is provided with an integral blend or coating of a perfluorocarbon silane compound. The gist is that it is decided to become.

As the material used as the rubber base material in the rubber-like surface layer material of the present invention, it is desirable to select silicone rubber as described above. For example, in the case of a rubber blade, not only the friction charging blade for the developing machine but also the photosensitive drum It can also be used as a cleaning blade to scrape off and clean the residual toner on the platen, and in the case of a rubber roll, a platen roll such as a facsimile or a thermal printer, or PP.
Considering that it can be used for various paper feed rolls such as C, facsimiles, printers, word processors, and personal computers,
Fluorine rubber, urethane rubber, EPDM, NBR, CR,
Chlorinated polyethylene and other rubber materials can also be used.

The perfluorocarbon silane compound applied to the present invention has the general formula Wherein, OR methoxy (-OCH ₃₎ alkoxy groups such as, x is shows a 2 or 3] is represented by.

When the surface of a substrate such as a rubber blade or a rubber roll is coated with this silane compound as a solvent solution or an aqueous solution, an alkoxysilane group [—Si (OR) _x ] is present in the aqueous solution, in the air, or adsorbed on the surface of the substrate. Is hydrolyzed to a silanol group [—Si (OH) _x ], which forms a hydrogen bond with a hydroxyl group on the surface of the substrate or a dehydration-condensation reaction to firmly bond with the perfluoroalkyl group (C _n F _{2n + 1} −) is immobilized on the surface of the substrate.

Further, when this silane compound is integral blended in a rubber substrate and a rubber blade or a rubber roll having at least the surface layer portion thereof is formed, the silane compound migrates to the rubber substrate surface layer, and perfluoroalkyl groups are arranged. . The surface of the perfluorocarbon thus obtained has properties such as hard feeling, water / oil repellency, and non-adhesiveness, and lowers the friction coefficient of the rubber molded product surface.

As the perfluorocarbon silane _{compound, a: CF 3 CH 2 CH} 2 Si (OCH 3) 3 b: CF 3 (CF 2) 3 CH 2 CH 2 Si (OCH 3)
₃ c: CF ₃ (CF ₂ ) ₇ CH ₂ CH ₂ Si (OCH ₃ ).
₃ d: e: CF ₃ (CF ₂ ) ₆ COOCH ₂ CH ₂ CH ₂ Si
_{(OCH 3) 3 f: CF} 3 (CF 2) 6 COSCH 2 CH 2 CH 2 Si
_{(OCH 3) 3 g: CF} 3 (CF 2) 6 CONHCH 2 CH 2 CH 2 S
_{i (OC 2 H 5) 3} h: CF 3 (CF 2) 7 SO 2 NHCH 2 CH 2 CH 2
Si (OCH ₃ ) ₃ i: j: CF ₃ (CF ₂ ) ₇ CH ₂ CH ₂ SCH ₂ CH ₂ S
_{i (OCH 3) 3 k:} CF 3 (CF 2) 9 CH 2 CH 2 SCH 2 CH 2 S
i (OCH ₃ ) ₃ l: m: Are exemplified.

The properties of the perfluorocarbon surface are evaluated by the critical surface tension γ _C. That is, unless the liquid has a surface tension equal to or lower than the critical surface force γ _C , the perfluorocarbon surface cannot be wetted. Therefore, the smaller the γ _C is, the harder the surface is obtained. It can be used as an index for water / oil repellency, non-adhesiveness, etc. This non-wetting surface is obtained when γ _C <about 15 dyn / cm,
The perfluorocarbon silane compound which gives such characteristics has 7 or more carbon atoms in the perfluoroalkyl group. Further, even if the perfluoroalkyl group has the same length, γ _C differs depending on the structure of the hydrocarbon chain, and a low γ _C is obtained by introducing a polar group such as an amide group, a sulfonic acid amide group or a carboxylic acid amide group. N- [3- (trimethoxysilyl) propyl] perfluoroheptylcarboxylic acid amide represented by the formula g or N-represented by the formula i
It is preferable to use [3- (trimethoxysilyl) propyl] -Nn-propyl perfluorooctyl sulfonic acid amide and the like.

Here, γ _C (unit: dyn / cm) of each of the perfluorocarbon silane compounds exemplified above for reference is listed below.

a: 20.6, b: 17.3, c: 13.8, d: 1
5.3, e: 17.4, f: 15.5, g: 14.4,
h: 13.0, i: 13.0, j: 14.7, k: 1
4.0, 1: 10.6, m: 10.4.

Also in the case of integral blend, the more carbon number of the perfluoroalkyl group, the easier the orientation to the surface layer. Therefore, the carbon number is preferably 7 or more.

As a treatment method for the rubber blade and the rubber roll, an integral blend method is preferable in the case of a rubber blade because abrasion is a prerequisite, and a coating method may be used in the case of a rubber roll, but the thickness of the perfluorocarbon silane layer by coating is 0.1. Since it is as thin as 0.5 g / m ² and there is a problem in the durability of the coating film, it is also preferable to use the integral blend method.

Furthermore, rubber hardness (JIS-A) is 3 in consideration of paper feeding.
A rubber material containing no perfluorocarbon silane compound was used as a core (FIG. 17) at 0 to 40 ° Hs, and rubber hardness (JIS-A) was 60 to 70 ° Hs, and the above silane compound was integral blended. If a rubber roll having a surface layer (FIG. 3) is used as the rubber material, the cost of this silane compound, which is relatively expensive, can be saved, and since the product can be produced by a general two-layer extrusion method, the cost of the final roll product can be kept low. You can

Integral blending of this perfluorocarbon silane compound into a rubber material such as silicone rubber is carried out by kneading a 100% stock solution of this silane compound into a rubber compound using a general rubber kneading device such as a two roll or Banbury mixer. It is performed by processing.
At this time, the ratio of the blend of the silane compound to 100 parts by weight of the rubber material may be appropriately selected within the range of 0.5 to 5 parts by weight while experimentally measuring the friction coefficient.

On the other hand, when coating this silane compound, after dissolving this compound in an organic solvent such as ethyl alcohol or isopropyl alcohol, the surface of the base material such as a rubber blade or a rubber roll is coated by means such as dipping, spraying or brush coating. Then, it is heated and dried at a temperature of around 100 ° C. for 5 to 30 minutes. The thickness of the coating paint film is may be selected from the range of 0.05 to 0.5 g / m ^2, typically the surface of the fluororesin parallel with 0.1 g / m ² is formed, a rubber-like surface layer material of the present invention Approximately 0.5 g / because it is worn by toner particles and PPC paper
It is preferable to set m ² .

As above, the rubber roll as the article provided with the rubber-like surface layer material, the rubber blade has been described as an example, but the present invention has a small friction coefficient, and is a field in which the excellent adhesive resistance without stickiness is utilized. The invention is not limited to these applications, and can be applied as a surface layer material such as a guide and various restraining plates in an electrostatic electrophotographic apparatus.

(Effect of the Invention) The rubber-like surface layer material according to the present invention is an integral blend or coating of a rubber base material with a perfluorocarbon silane compound, and therefore has a low friction coefficient, no tackiness, and stain resistance. It is excellent and extremely useful as a triboelectric charging blade for developing machines and fixing rolls in electrostatic electrophotographic devices.

(Examples and Comparative Examples) Hereinafter, typical embodiments of the present invention will be described with reference to Examples and Comparative Examples.

Example 1. And Comparative Example 1. Silicone rubber KE with rubber hardness (JIS-A) 50 ° Hs
After kneading 2 parts by weight of vulcanizing agent C-8 (manufactured by Shin-Etsu Chemical Co., Ltd.) with 100 parts by weight of 951 U (manufactured by Shin-Etsu Chemical Co., Ltd.), N- [3 A rubber compound A was prepared by mixing 2 parts by weight of-(trimethoxysilyl) propyl] -Nn-propylpa-fluorooctylsulfonic acid amide MF-160 (trade name, manufactured by Mitsubishi Metals Co., Ltd.).

A rubber compound B was also prepared by removing MF-160 from this formulation.

Next, as shown in FIG. 2, the end portions in the width direction are aligned on the surface of a SUS304 steel strip having a thickness of 0.1 mm × a width of 25 mm × a length of 300 mm by press forming, and a thickness of 1 mm × a width of 10 mm × a length of 3
Apply a rubber sheet of 00 mm to the above rubber compounds A and B
Were integrally molded by using to prepare triboelectric charging blades A and B. The triboelectric charging blade B corresponds to the one currently used.

The friction coefficient of this frictional charging blade was measured by a friction measuring device TR type (manufactured by Toyo Seiki Seisakusho, Ltd., trade name) to obtain a friction speed of 5
When measured at 00 mm / min, the charging blade B shows 1.2
5, the value of the charging blade A was 0.85.

Further, a developing machine FX-2700 for charging blade abrasion test
(Fuji Xerox Co., Ltd. product name), the surface of this developing roll (φ25 mm) was axially sanded with # 800 sandpaper, and after cleaning with ethyl alcohol, this was applied at a linear pressure of 0.3 kg / cm. The development roller was rotated at a peripheral speed of 6 while the friction charging blade was attached so as to be pressed and toner (black) B228 (trade name, manufactured by Fuji Xerox Co., Ltd.) was supplied.
The blade was rotated at 00 mm / sec (460 rpm) for 60 minutes to measure the wear depth of the blade. As a result, the charging blade B equivalent to the current product had a wear depth of 11 to 12 μm, whereas the charging blade A had a low value of 6 to 7 μm.
It showed twice as much wear durability as the current product. The toner layers for both charging blades A and B were evenly formed with a thickness of 20 to 30 μm, and clogging due to toner adhesion did not occur.

Example 2 Silicone rubber KE having a rubber hardness (JIS-A) of 70 ° Hs
-172 U (manufactured by Shin-Etsu Chemical Co., Ltd., trade name) to 100 parts by weight of vulcanizing agent C-2 (manufactured by Shin-Etsu Chemical Co., Ltd.,
Trade name) After blending 2 parts by weight, N- [3- (trimethoxysilyl) propyl] perfluoroheptylcarboxylic acid amide, MF-150 (trade name, manufactured by Mitsubishi Metals Co., Ltd.)
2 parts by weight of rubber compound A2 was prepared.
Next, with respect to 100 parts by weight of silicone rubber SE1642U (manufactured by Toray Silicon Co., Ltd., trade name) having a rubber hardness (JIS-A) of 25 ° Hs, a vulcanizing agent RC-2FD (manufactured by Torre Silicon Co., Ltd., 1 part by weight of the product) was blended and a silicone rubber roll having a soft layer diameter of 22 mm and a hard layer thickness of 1.5 mm, that is, an outer diameter of 25 mm was molded by a two-layer extrusion / hot air vulcanization method. When this was used as a backup roll of a fixing roll of PPC, it was in a usage state in which toner adhesion was low and paper feeding property was good.

(Effects of the Invention) The rubber-like surface transmission device according to the present invention comprises a perfluorocarbon layer formed on a rubber substrate such as silicone rubber by an integral blending method which is a general kneading method or a simple coating method. The surface layer has characteristics such as a hard feeling, water / oil repellency, and non-adhesiveness.

This surface layer material also controls the friction coefficient by controlling the compounding ratio of the silane compound to the rubber base material in the case of integral blending, and the dissolution ratio of the silane compound in the solvent in the case of coating, respectively. It can be adjusted arbitrarily.

Therefore, when this is applied to a charging friction blade, the friction coefficient can be reduced as compared with the conventional silicone rubber blade, and the abrasion resistance at the time of forming the toner layer is improved. Will be possible.

Above all, when silicone rubber is selected as the rubber base material for the surface layer material, this satisfies the basic requirement for forming a toner layer that always exposes a new surface, and the toner like when using other rubber materials is used. Does not cause a layer formation failure due to the sticking of.

On the other hand, in the case of a rubber roll such as a fixing roll, since the inner layer of the roll is soft, the surface layer has a hard feeling, and can be made a non-adhesive surface, the paper feeding property is good, and a roll to which toner does not adhere is obtained. This property is also effective when applied to other paper feed rolls and platen rolls.

Furthermore, silicone rubber products have been conventionally used for medical parts such as O-ring packing, rubber caps, rubber droppers, and rubber tubes, but these silicone rubber products are adhesive and can be automatically aligned. Although it was difficult to align and automatic setting was difficult, the automatic setting becomes easy by applying the product of the present invention.

In addition, the platen roll of a thermal printer such as a facsimile uses a conductive rubber roll to prevent static electricity, but when the paper is pressed against the platen roll by the thermal head, the carbon-blended conductive rubber roll stains the paper black. For this reason, a white conductive rubber roll containing an expensive antimony oxide-doped titanium oxide / tin oxide powder is usually used. However, by applying the surface layer material of the present invention to a carbon-containing conductive rubber roll, it is possible to provide an inexpensive conductive rubber roll free from paper stains.

Further, a conductive rubber containing a metal powder such as Ag, Ni, or Cu is used as an interconnector or an electromagnetic wave shield material, and a rubber magnet containing a Sm / Co magnetic powder or Nd-Fe-B magnetic powder is a motor. However, when the product of the present invention is applied to the rubber base material surface, it imparts water repellency to the surface of the rubber base material, so that the oxidation of metal components, which has been a problem of performance deterioration, can be effectively prevented.

[Brief description of drawings]

Each of the drawings relates to an embodiment of the present invention. FIG. 1 is a vertical sectional view of a developing device, FIG. 2 is a perspective view of a friction charging blade used in the device of FIG. 1, and FIG. 3 is a vertical section of a fixing device. It is a side view. (Explanation of reference numerals in the drawings) 1 ... Developing device, 2 ... Hopper-like container 3 ... Developing roll, 4 ... Friction charging blade 5 ... Recovering blade 6 ... Toner particles, 7 ... Photosensitive drum 8 ... ... Spring steel strip, 9 ... Rubber sheet 10 ... Mounting hole, 11 ... Heat roll 12 ... Heater, 13,16 ... Metal core 14 ... Fluororesin coating layer 15 ... Backup roll 17 ... Soft Rubber layer, 18 ... Hard rubber layer 19 ... PPC paper, 20 ... Toner pattern

Claims (3)

[Claims] 1. A rubber-like surface layer material obtained by integral blending or coating a perfluorocarbon silane compound on a rubber base material. 2. A rubber roll provided with the rubber-like surface layer material according to claim 1 on at least the surface layer portion. 3. A rubber blade comprising the rubber-like surface layer material according to claim 1 provided on at least the surface layer portion thereof.