JPH09120196A - Elastic roller for electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to maintain a coefft. of friction over a long period of without roughening surface roughness by adopting the constitution obtd. by coating at least a surface layer with a resin having the post-curing film hardness of pencil hardness B to 6H. SOLUTION: The outer periphery of a conductive layer 2 laminated on the outer periphery of the revolving shaft 1 is coated with the resin, by which the surface layer 3 is formed. The front surface of the conductive elastic layer 2 may be coated with the resin or both ends of the conductive elastic layer 2 may be coated with the resin as well. The resin is not particularly restricted, insofar as the post-curing film hardness of pencil hardness B to 6H. The sufficiently high surface hardness is not obtainable if the post-curing film hardness is below the pencil hardness B. The resin itself is too rigid and fails to follow up the elasticity of the conductive elastic layer if the post-curing film hardness exceeds the pencil hardness 6H. The occurrence of crack and fissure and the impairment of the image quality are resulted in such a case.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an elastic roller for an electrophotographic apparatus, which has excellent image quality.

[0002]

2. Description of the Related Art An electrophotographic apparatus has a photoconductor provided with a photoconductor layer on a surface thereof. In operation, an outer peripheral surface of the photoconductor is uniformly charged. An electrostatic latent image is formed by exposing the outer peripheral surface of the electrostatic latent image via a copied image, and a toner image is formed by attaching toner to the electrostatic latent image, and the toner image is transferred and fixed on paper or the like. It is.

In this process, as shown in FIG. 3, in the peripheral member of the photoconductor 8, the toner 9 is supplied from the charging roller 5 and the toner storage tank 10 which give electric charges to the photoconductor 8.
An elastic roller that requires various conductivity is used, such as a developing roller 6 that is conveyed to the recording medium, and a transfer roller 7 that is used when the toner 9 is transferred from the photoconductor 8 to the recording paper 11.

As shown in FIG. 4, such an elastic roller is usually laminated on a rotary shaft 41 that gives rotation to the roller and a concentric outer periphery of the rotary shaft 41, and transmits the rotation of the rotary shaft 41. A conductive elastic layer 42 having conductivity for imparting conductivity to the roller, and also having elasticity for imparting elasticity to the roller, is laminated concentrically on the outer periphery of the conductive elastic layer 42, and the conductive elastic layer 42 is provided. Of the surface layer 43 that transmits the rotation of the roller and contacts the mating material of the roller.

Conventionally, as such an elastic roller,
The surface layer is JIS A hardness 20 because it has excellent mechanical strength and abrasion resistance and does not damage the mating material.
It has a low hardness of ~ 45. However, when the hardness of the surface layer of the elastic roller is low, the coefficient of friction with the mating material such as the photoconductor increases, so that the roller cannot be smoothly rotated.

Therefore, in order to reduce the friction coefficient, it has been proposed to use a hard layer coated as the surface layer, but various problems have arisen with respect to how to form the hard layer. It is not definite, and a means for reducing the coefficient of friction is added by adding a filler to such a coating layer or roughening the surface roughness of the roller.

However, if the surface roughness is roughened in this way, the charging property becomes uneven, the toner becomes thinner, and the uniform carrying property becomes uneven, which is not preferable in terms of quality and the surface roughness becomes rough. It is desired to reduce the coefficient of friction without any problems.

The surface layer is usually 30 to 100 μm.
Since the friction coefficient cannot be reduced unless the thickness is set to a large value, thick film coating is unavoidable, but if the hard layer becomes thick, the outer layer will be distorted during long-term use or during rest, resulting in image quality. Will result in damage to.

As a method of lowering the friction coefficient without lowering the surface roughness, for example, a method of coating silicone as a surface layer has been proposed. In this method, the adhesion of the conductive elastic layer to polyurethane is improved. Inferior,
Peeling occurs during use, which is a practical problem.

[0010]

As described above, the reduction of the friction coefficient of the elastic roller can prevent the occurrence of distortion of the roller, improve the mechanical durability such as the peeling resistance of the roller, and prevent the occurrence of long-term rest. Although it is important to prevent contact with members and the like and many proposals have been made, none of them have been put into practical use because of insufficient effect.

In view of the above situation, it is an object of the present invention to provide an elastic roller for an electrophotographic apparatus in which the friction coefficient is maintained for a long time without roughening the surface roughness.

[0012]

An object of the present invention is to provide an elastic roller for an electrophotographic apparatus, which is formed by concentrically laminating a conductive elastic layer on the outer periphery of a rotary shaft and concentrically laminating a surface layer on the outer periphery thereof. In at least the surface layer, the pencil hardness B
It lies in that it is coated with a resin having a film hardness after curing of 6H. Hereinafter, the present invention will be described in detail.

At least the surface layer of the elastic roller for an electrophotographic apparatus of the present invention is coated with a resin having a cured film hardness of pencil hardness B to 6H. FIG. 1 shows an example in which the surface layer is coated with the resin.
Shown in In the present invention, the outer periphery of the conductive elastic layer 2 laminated on the outer periphery of the rotating shaft 1 is coated with the above resin as shown in (a) to form a surface layer. (B)
As described above, the resin may be coated on the entire surface of the conductive elastic layer 2, and both ends of the conductive elastic layer 2 may be coated with the resin.

The above-mentioned resin is not particularly limited as long as it has a cured film hardness of pencil hardness B to 6H.
Examples thereof include acrylic urethane, lactone-modified acrylic urethane, acrylic silicone, thermoplastic urethane, and phenol resin.

The cured film of the above resin has a pencil hardness of B to 6H. If the hardness of the coating film after curing is less than the pencil hardness B, the surface hardness cannot be sufficiently increased, and a thickness is required to modify until the friction coefficient is reduced, and causes such as distortion are wiped off. I can't. Further, when the coating hardness after curing exceeds the pencil hardness of 6H, the resin itself becomes too rigid and cannot follow the elasticity of the conductive elastic layer, resulting in cracks or cracks and impairing the image quality.

The present invention limits only the film hardness of the above resin after curing, and does not specify the composition of the above resin. Since the coefficient of friction can be reduced by limiting the hardness of the coating film after curing of the resin, it is not necessary to use fluorine particles or silicone having low coating adhesion,
It is possible to select a resin that attaches importance to the adhesiveness with the conductive elastic layer, and it is easy to reduce friction.

A second aspect of the present invention is an elastic roller for an electrophotographic apparatus, which is formed by concentrically laminating a conductive elastic layer on the outer periphery of a rotary shaft and concentrically laminating a surface layer on the outer periphery thereof. The surface layer has a pencil hardness of B to 6H.
After being cured, the resin is impregnated with a resin having a film hardness.

In the second aspect of the present invention, the pencil hardness B
At least the surface of the conductive elastic layer is impregnated with a resin having a film hardness after curing of 6H. In the present invention described above, the resin having the cured film hardness of pencil hardness B to 6H has a certain thickness because it is coated on the surface of the conductive elastic layer. Since the resin is impregnated in the conductive elastic layer, it has no thickness, as is clear from FIG. 2 showing an impregnated example.
The effect of the present invention can be exhibited more favorably. FIG.
(A) is an example in which only the skin portion of the conductive elastic layer is impregnated, and (b) in FIG. 2 is an example in which both end portions of the conductive elastic layer are impregnated in addition to the skin portion.

The elastic roller for an electrophotographic apparatus of the present invention comprises:
Since the reduction of the friction coefficient can be realized simply by coating or impregnating the surface layer of the conductive elastic layer with a resin, it is possible to achieve a thin surface layer and to impart conductivity to the surface layer. Only the conductive property of the conductive elastic layer can sufficiently fulfill the conductive function. In order to impart conductivity to the surface layer, usually, a conductive filler such as carbon is added to the surface layer material, but this increases the particle size of the treatment agent of the surface layer or causes poor dispersion of the filler. It was causing a malfunction. In the elastic roller for an electrophotographic apparatus of the present invention, the above problems can be completely solved.

[0020]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Examples 1 to 5 and Comparative Examples 1 to 3 (Preparation of Rotating Shaft and Conductive Elastic Layer) For 100 parts by weight of polyadipate ester polyol (Nipporan 4032 manufactured by Nippon Polyurethane Industry Co., Ltd.), 1 part of conductive carbon was used.
After adding 100 parts by weight and dehydrating under reduced pressure at 100 ° C., tolylene diisocyanate (Millionate T-80, manufactured by Nippon Polyurethane Industry Co., Ltd.) was added to 7.5 parts by weight of the polyol.
Parts by weight were added and mixed, and the mixture was poured into a mold at 110 ° C. in which a core metal to be a rotating shaft was set in advance, and was cured for 3 hours. Further, after demolding, after-curing at 110 ° C. for 24 hours, cooling, and polishing to a predetermined size, a conductive elastic layer having a resistance value of 10 ⁶ Ω was obtained.

(Preparation of Surface Layer I / Coating) The following resins I to VI were used to adjust the solid content concentration to 10 to 15%, and the conductive elastic layer of the elastic roller obtained above was prepared by a dipping method. The surface was treated. Then, it was cured by the following curing method.

(Preparation of Surface Layer II / Impregnation) Resin I below
The elastic roller obtained above was immersed in ~ VI for 1 to 60 minutes, pulled up, and then the resin adhering to the elastic roller was removed with a solvent. Then, it was cured by the following curing method.

The resins used were as follows: Resin I Acrylic urethane (KRM7039, manufactured by Daicel Chemical Industries, Ltd., solid content 100%) Curing method: UV crosslinking, curing means: UV irradiation, coating hardness after curing: pencil hardness 6H. Resin II Lactone-modified acrylic urethane (Placcel 2209 /
Duranate 24A, manufactured by Daicel Chemical Industries, Solid content 5
0%) Curing method: isocyanate cross-linking, curing means: room temperature x 5
Sun, film hardness after curing: pencil hardness B.

Resin III Acrylic Silicone (Clearmer UA90, manufactured by Sanyo Chemical Industry, solid content 50%) Curing method: hydrolysis of silyl group, curing means: 100 ° C. ×
60 minutes, film hardness after curing: pencil hardness 2H. Resin IV Thermoplastic urethane (Nipporan 5109, manufactured by Nippon Polyurethane Company, solid content 30%) Curing method: evaporation of solvent, curing means: 110 ° C. × 60 minutes,
Film hardness after curing: pencil hardness H.

Resin V Thermoplastic urethane (Nipporan 5232, manufactured by Nippon Polyurethane Company, solid content 40%) Curing method: evaporation of solvent, curing means: 110 ° C. × 60 minutes,
Film hardness after curing: pencil hardness 2B. Resin VI Phenol resin (Chemlock 218, manufactured by Lord Co., solid content 20%) Curing method: amine crosslinking, curing means: 110 ° C. × 60 minutes,
Film hardness after curing: Pencil hardness 6H or more.

Measurement of Friction Coefficient As shown in FIG. 5, the friction coefficient was measured by measuring the resistance to polyethylene terephthalate (PET: photoconductor surface) with a load of 100 g as shown in FIG. 5 (rubbing speed 200 mm). / Min). Evaluation in actual machine Toshiba Co., Ltd. electrophotographic facsimile COPIX TF58
Using H, the evaluation with the developing roller was performed using an actual machine.
Evaluation items are images after running 10,000 sheets and 40 ° C x 3
The first image after leaving for 0 days and the state of the machine at startup were observed.

The film thickness was determined by [(outer diameter after surface treatment)-(outer diameter before surface treatment)] / 2 by a laser outer diameter measuring machine. The outer diameter increase rate is [(outer diameter after surface treatment)-(outer diameter before surface treatment)] /
(Outer diameter before surface treatment) × 100.

[0029]

[Table 1]

[0030]

EFFECT OF THE INVENTION Since the elastic roller for electrophotographic apparatus of the present invention has the above-mentioned constitution, the friction coefficient can be easily reduced, and the stable image quality can be maintained for a long period of time without increasing the surface roughness. You can

[Brief description of the drawings]

FIG. 1 is a diagram showing an example in which a surface layer of an elastic roller for an electrophotographic apparatus of the present invention is a conductive elastic layer coated with a resin.

FIG. 2 is a diagram showing an example in which the surface layer of the elastic roller for an electrophotographic apparatus of the present invention is a layer in which a conductive elastic layer is impregnated with a resin.

FIG. 3 is a schematic diagram showing an elastic roller in an electrophotographic apparatus.

FIG. 4 is a schematic diagram showing the structure of an elastic roller.

FIG. 5 is a diagram showing measurement of a friction coefficient in an example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotating shaft 2 conductive elastic layer 3 resin coating layer 4 resin impregnation part 5 charging roller 6 developing roller 7 transfer roller 8 photoconductor 9 toner 10 toner storage tank 11 recording paper 16 elastic roller 17 holder 18 PET film 19 moving table 20 balancer fulcrum 21 Load Cell 22 Weight 41 Rotating Shaft 42 Conductive Elastic Layer 43 Surface Layer

Claims (2)

[Claims] 1. An elastic roller for an electrophotographic apparatus, wherein a conductive elastic layer is concentrically laminated on the outer periphery of a rotating shaft, and a surface layer is concentrically laminated on the outer periphery of the rotating shaft. At least the surface layer has a pencil hardness. An elastic roller for an electrophotographic apparatus, characterized by being coated with a resin having a film hardness after curing of B to 6H. 2. An elastic roller for an electrophotographic apparatus, wherein a conductive elastic layer is concentrically laminated on the outer periphery of a rotating shaft, and a surface layer is concentrically laminated on the outer periphery of the rotary shaft. At least the surface layer has a pencil hardness. An elastic roller for an electrophotographic apparatus, characterized in that it is impregnated with a resin having a coating hardness after curing of B to 6H.