JP2001290376A - Transfer and conveying belt for electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transfer and conveying belt for an electrophotographic device which is in contact with a photoreceptor in a specified width through a recording medium to transfer a toner image on the photoreceptor to the recording medium and to convey the recording medium to a fixing device. SOLUTION: A surface layer 3 consisting of at least two layers including a resistance controlling layer 4 and an outermost layer 5 is formed on an elastic member 2 in such a manner that the outermost layer 5 does not contain conductive fine particles and the volume specific resistance of the outermost layer 5 is higher than the volume specific resistance of the resistance controlling layer 4. The outermost layer 5 consists of a polymer containing a fluorinated resin and is preferably 0.5 to 70 μm thick. The elastic member 2 is preferably 0.2 to 2 mm thick with <=0.1 mm fluctuation range. The belt preferably has <=8% elongation and <=8 μm surface roughness Rz.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer belt for use in an electrophotographic apparatus.

[0002]

2. Description of the Related Art Conventionally, as a transfer device for transferring a toner image formed on a photoreceptor to a recording medium such as paper, a transfer method such as corotron or scorotron using corona discharge has been used. However, these methods have a problem of ozone generation because corona discharge is used. In order to solve this problem, a transfer roller composed of an elastic member is brought into contact with the photoreceptor from the back surface of the recording medium, and a voltage is applied to the shaft of the transfer roller to generate a transfer electric field, thereby causing a transfer of toner. A transfer method has been developed. When a transfer roller is used, a contact width (nip width) with the photoreceptor is required, so the elasticity of the transfer roller surface must be regulated, and a separate transport roller for transporting the recording medium to the fixing device is provided. And there is a problem in space saving.

On the other hand, in order to save space, there is a case where a transfer / conveying belt having both a toner transfer and a recording medium conveyance using a conductive endless belt is used. In this case, the conductive endless belt is driven multi-axially by using a plurality of rollers, forms a surface potential on the surface of the belt, suctions and conveys the recording medium, and transfers the toner image to the recording medium at the transfer position. Do.

If corona discharge is used to form a surface potential by charging the surface of the conductive endless belt, the above-described problem of ozone generation occurs. If the contact charging method is used, the number of parts increases. However, there is a problem that the effect of space saving is small.

[0005]

As a method of improving the contact charging method, it is considered that the endless belt itself has proper conductivity and a voltage is applied to the surface of the belt from one roller used for driving the belt. However, this has the following problems.

(A) To keep the potential of the belt surface constant. This requires that the volume resistivity of the outermost layer of the belt be high and constant. (B) The inner surface of the belt has a certain resistance or more. If the resistance of the inner surface of the belt is low, current flows to the other roller via the inner peripheral surface, and the charge of the outermost layer cannot be kept constant. (C) The belt surface has releasability. If the releasability is low, the toner adheres to the belt surface, and stains the recording medium.

An object of the present invention is to provide a transfer for an electrophotographic apparatus in which a photoconductor is contacted with a fixed width via a recording medium, a toner image on the photoconductor is transferred to the recording medium, and the recording medium is conveyed to a fixing device. It is to provide a conveyor belt.

[0008]

According to the present invention, there is provided a transfer / transport belt for an electrophotographic apparatus having a surface layer on an elastic member and applying a voltage from the elastic member side, wherein the surface layer is a resistance adjusting layer on the elastic member side. An electrophotographic apparatus comprising: at least two layers including an outermost layer and a surface-side outermost layer, wherein the outermost layer does not contain conductive fine particles, and a volume resistivity of the outermost layer is larger than a volume resistivity of the resistance adjusting layer. Transfer transfer belt.

According to the present invention, the transfer / transport belt for an electrophotographic apparatus has a structure in which at least two surface layers including a resistance adjusting layer and an outermost layer are provided on an elastic member, and the outermost layer is made of a conductive material. Contains no fine particles. If the outermost layer contains the conductive fine particles, the volume resistivity of the outermost layer is reduced in the portion where the conductive fine particles are present, and the potential on the belt surface cannot be made uniform. By setting the volume resistivity of the outermost layer higher than that of the resistance adjusting layer, a constant transfer electric field can be maintained on the outermost layer.

The present invention is also characterized in that the outermost layer is made of a polymer containing a fluorine group.

According to the present invention, the outermost layer is composed of a polymer containing a fluorine group. As a result, the outermost layer has high releasability, no excess toner remains on the belt, and the image is not stained.

Further, according to the present invention, the outermost layer preferably has a thickness of 0.5 to 7
0 μm. According to the invention, the thickness of the outermost layer is comprised between 0.5 and 70 μm. This is 0.
If the thickness is less than 5 μm, there is no point in providing the outermost layer, and the surface potential of the belt cannot be maintained uniformly due to the effect of the conductive fine particles present in the resistance adjusting layer. On the other hand, if it exceeds 70 μm, the resistance of the entire belt becomes too large, and the surface potential required for transfer decreases.

Further, according to the present invention, when conductive fine particles are added to the resistance adjusting layer, the conductive fine particles have a particle size of 30 to 500 nm.
Characterized in that it is conductive carbon.

The resistance adjusting layer is a layer provided for adjusting the resistance of the entire belt which differs depending on the purpose of use. In a high resistance belt, it is not necessary to add conductive fine particles to the resistance adjusting layer. In a low resistance belt, a necessary amount of conductive fine particles is added to the resistance adjusting layer. As the conductive fine particles, a particle size of 30 to
500 nm conductive carbon is preferred. Conductive carbon having a thickness of less than 30 nm is difficult to produce, and if the thickness is less than 30 nm, the carbon particles lose electrical conductivity. And this is 500
If it exceeds nm, the thickness becomes about the same as the film thickness of the outermost layer, the volume specific resistance of the outermost layer is reduced at the point where carbon particles are present, and the surface potential cannot be maintained uniformly.

Further, in the present invention, the elastic member may be formed of one or more of chloropyrene rubber, nitrile rubber, urethane, epichlorohydrin, and a copolymer containing epichlorohydrin-ethylene oxide as a main component. It is characterized in that conductive fine particles are added to rubber and the volume resistivity is adjusted to 10 ⁶ to 10 ¹² Ω · cm.

According to the present invention, the elastic member is formed by adding conductive fine particles to the polar rubber, and has a volume specific resistance of 10 ⁶ to 1.
It is adjusted to 0 ¹² Ω · cm, preferably 10 ⁹ to 10 ¹¹ Ω · cm. The polar rubber easily disperses the conductive fine particles and easily controls the conductivity of the elastic member. If the volume resistivity of the elastic member is less than 10 ⁶ Ω · cm, a current flows in the circumferential direction through the elastic member, and a surface potential cannot be obtained on the belt surface. If this exceeds 10 ¹² Ω · cm, the voltage from the roller cannot be transmitted to the surface layer, and the required surface potential on the belt surface cannot be obtained.

Examples of the conductive fine particles include carbon black, metal powder, tin oxide and the like. Carbon black is preferred because it is easily available and can be easily dispersed in the polar rubber.

Further, according to the present invention, the elastic member has a thickness of 0.2 to 0.2.
It is characterized in that the thickness is 2 mm and the variation width of the thickness is 0.1 mm or less.

According to the present invention, the thickness of the elastic member is 0.2
The thickness variation width is set to 0.1 mm or less, preferably 0.05 mm or less. The thickness of the elastic member is 0.2
If the belt is less than 2 mm, it is difficult to manufacture the belt. If it exceeds 2 mm, the voltage from the roller cannot be transmitted to the surface layer, and the required surface potential on the belt surface cannot be obtained. It is preferable that the variation width of the thickness of the elastic member is small, and when the variation width exceeds 0.1 mm, even if the conductive fine particles are uniformly dispersed, a difference in electric resistance between the thick portion and the thin portion can be obtained, The surface potential of the belt surface is not uniform.

The present invention is further characterized in that the belt elongation η is 8% or less. According to the present invention, the belt elongation η defined as follows is 8% or less. The transfer conveyance belt for an electrophotographic apparatus is used by being stretched around at least two rollers 41 and 42 as described in FIG. Assuming that the distance between the centers of the two rollers 41 and 42 is L and the outer diameters of the two rollers 41 and 42 are d1 and d2, the theoretical value of the belt 1 stretched over the two rollers 41 and 42 is The inner circumference D ₀ is represented by the following equation.

[0021]

(Equation 1)

On the other hand, the actual inner circumferential length of the belt 1 is represented by D
Then, the belt elongation η is obtained by the following equation. η = (D ₀ / D−1) × 100% (2)

When the belt elongation exceeds 8%, the photosensitive member 1
The contact width between belt 1 and belt 1 becomes too large, which is not preferable.

In the present invention, the belt has a surface roughness Rz of 8
μm or less. According to the present invention, the surface roughness Rz of the belt is 8 μm or less. If the surface roughness Rz of the belt exceeds 8 μm, unevenness of the belt surface becomes large, and transfer omission occurs in the concave portion.

The present invention is further characterized in that the water contact angle θ of the belt surface is 90 ° or more.

According to the present invention, the water contact angle θ on the belt surface
Is 90 ° or more. When the water contact angle θ on the surface is as large as 90 ° or more, water repellency is obtained, and the releasability of the toner is improved.

[0027]

FIG. 1 is a perspective view of a transfer / conveyance belt 1 according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of the transfer / conveyance belt 1. The transfer conveyance belt 1 includes an elastic member 2 and a surface layer 3. The surface layer 3 includes a resistance adjusting layer 4 on the elastic member 2 and an outermost layer 5 on the surface side.
Does not contain conductive fine particles.

FIG. 3 is a cross-sectional view showing the structure of an exposure and development section of an electrophotographic apparatus using the transfer and conveyance belt 1 of the present invention. The charging roller 21 uniformly applies, for example, a negative charge to the surface of the photoreceptor 11 having a right cylindrical shape.
The charged photoreceptor 11 is driven to rotate in the direction of arrow 16 to reach the exposure area 12, where the image is exposed by the laser beam from the exposure means 22, and the charge on the exposed portion is neutralized and statically charged. An electrostatic latent image is formed.

The photoreceptor 11 is further driven to rotate and reaches the developing area 13, where the electrostatic latent image is developed with toner. The toner is negatively charged in frictional contact with each other by the stirring means 24 in the developing device 23. The charged toner is supplied to a developing roller 26 via a supply roller 25, and excess toner is regulated by a regulating blade 27, and an optimal amount of toner is supplied from the developing roller 26 to the photosensitive member 1.
1 is supplied to the portion of the neutralized electrostatic latent image, and is developed as a toner image.

The photoreceptor 11 is further rotated to reach the transfer area 14, and the toner image is transferred to a recording medium such as paper 28 supplied between the photoreceptor 11 and the transfer belt 1 of the present invention. You. The transfer conveyance belt 1 is stretched between two rollers 41 and 42 and driven in the direction of arrow 40.

Roller (driven roller) 4 close to photoconductor 11
Reference numeral 1 denotes a positive electrode of a high-voltage power supply device 45 connected to the shaft 43, a positive charge of the transfer conveyance belt 1 is given through a conductive elastic layer 44 around the shaft 43, and a negative charge by the positive charge of the transfer conveyance belt 1. The toner on the photoreceptor 11 charged to the photoreceptor 11 is sucked, and the toner image on the photoreceptor 11 is transferred to the paper 28 conveyed between the photoreceptor 11 and the transfer conveyance belt 1. The other roller (drive roller) 42 is connected to a drive source such as a motor (not shown). The photoconductor 11 is further driven to rotate, reaches the cleaning area 15, the residual toner on the photoconductor 11 is cleaned by the cleaning blade 29, and the remaining charge is removed by the charge removing unit 30.

The paper 28 is supplied between the photoreceptor 11 and the transfer / transport belt 1 by two paper feed rollers 46,
After the toner image is transferred, the toner image is conveyed to the fixing device 47, where the toner image is fixed.

Hereinafter, the present invention will be described in more detail by using belts produced in Examples and Comparative Examples.

Example 1 100 parts by weight of low nitrile type nitrile rubber (NBR), 30 parts by weight of carbon black (HAF carbon manufactured by Mitsubishi Chemical Corporation) as conductive fine particles, 5 parts by weight of zinc oxide, and dioctyl phthalate (DOP) 5 parts by weight, 1 part by weight of stearic acid, 0.5 part by weight of sulfur, 1 part by weight of N-cyclohexyl-2-benzothiazyl-sulfenamide as a vulcanization accelerator and 1.5 parts by weight of tetramethylthiuram disulfide Mix and vulcanize at 160 ° C for 30 minutes by tape wrapping vulcanization method.
A belt coarse material having a thickness of 1.0 mm and a thickness of 1.0 mm was produced. The surface of the belt coarse material is polished to a thickness of 0.6 mm and a surface roughness Rz.
An elastic member for a belt having a thickness of 4.5 μm and a volume resistivity of 1 × 10 ¹¹ Ω · cm was obtained.

The coating material 1 shown in Table 1 was air-dried to a thickness of 10 μm on the elastic member for a belt by a spray coating method. A coating agent 2 was further applied thereon by a spray coating method so as to have a thickness of 10 μm, and then dried in a hot air oven at 140 ° C. for 30 minutes to obtain a belt. Table 2 shows the physical properties of this belt. Table 3 shows the results of image evaluation using this belt as the transfer conveyance belt 1 in FIG.

Example 2 100 parts by weight of a non-sulfur-modified chloroprene rubber (CR), 40 parts by weight of carbon black (FEF carbon manufactured by Tokai Carbon), 5 parts by weight of zinc oxide and 4 parts by weight of magnesium oxide as conductive fine particles And 5 parts by weight of a naphthenic oil, 1 part by weight of stearic acid, and 0.5 part by weight of 2-mercaptoimidazoline as a vulcanization accelerator, and vulcanized at 160 ° C. for 30 minutes by a tape wrapping vulcanization method. A belt coarse material having an inner diameter of 50 mm and a thickness of 1.0 mm was produced. The surface of the belt coarse material is polished to have a thickness of 0.6 mm, a surface roughness Rz of 3.8 μm, a thickness variation width in the circumferential direction of 0.04 mm, and a length variation width in the longitudinal direction of 0.03 m.
Thus, an elastic member for a belt having a volume resistivity of 3 × 10 ¹¹ Ω · cm was obtained.

The coating material 3 shown in Table 1 was applied to the elastic member for the belt by spray coating so as to have a thickness of 15 μm, and dried at 80 ° C. for 15 minutes in a hot air oven. Further, a coating agent 4 is further applied thereon by a spray coating method so as to have a thickness of 10 μm.
The belt was dried at 130 ° C. for 30 minutes in a hot air oven. Table 2 shows the physical properties of this belt. Table 3 shows the results of image evaluation using this belt as the transfer conveyance belt 1 in FIG.

Example 3 An elastic member for a belt was obtained in the same manner as in Example 2, and a coating agent 5 shown in Table 1 was applied to the elastic member for the belt by spray coating to a thickness of 15 μm. Work,
Dried in a hot air oven at 80 ° C. for 15 minutes. A coating agent 6 is further applied thereon by a spray coating method so as to have a thickness of 10 μm.
After drying in a hot air oven for a minute, a belt was obtained. Table 2 shows the physical properties of this belt. Table 3 shows the results of image evaluation using this belt as the transfer conveyance belt 1 in FIG.

Comparative Example 1 In the same manner as in Example 1 until the coating agent 1 was applied and dried, instead of applying the coating agent 2, the coating agent 1 was applied again and air-dried to obtain a belt. Table 2 shows the physical properties of this belt. Table 3 shows the results of image evaluation using this belt as the transfer conveyance belt 1 in FIG.

Comparative Example 2 In the same manner as in Example 2 until the coating agent 3 was applied and dried, instead of applying the coating agent 4, the coating agent 3 was applied again, and then air-dried for 30 minutes at 130 ° C. The belt was obtained by drying in a hot air oven. Table 2 shows the physical properties of this belt.
Table 3 shows the results of image evaluation using this belt as the transfer conveyance belt 1 in FIG.

Comparative Example 3 In the same manner as in Example 3 until the coating agent 5 was applied and dried, instead of applying the coating agent 6, the coating agent 5 was applied again, and then air-dried at 130 ° C. for 30 minutes. The belt was obtained by drying in a hot air oven. Table 2 shows the physical properties of this belt.
Table 3 shows the results of image evaluation using this belt as the transfer conveyance belt 1 in FIG.

Comparative Example 4 A coarse belt material was obtained in the same manner as in Example 2, and the coarse belt material was 0.6 mm in thickness, 3.8 μm in surface roughness Rz, 0.1 mm in width in the circumferential direction, and 0.1 mm in longitudinal direction. Thickness fluctuation width in direction 0.0
A belt elastic member having a thickness of 3 mm and a volume resistivity of 3 × 10 ¹¹ Ω · cm was obtained, and a coating agent 3 and a coating agent 4 were applied thereto in the same manner as in Example 2 to obtain a belt. Table 2 shows the physical properties of this belt. Table 3 shows the results of image evaluation using this belt as the transfer conveyance belt 1 in FIG.

Comparative Example 5 A belt coarse material was obtained in the same manner as in Example 2, and this belt coarse material was 0.6 mm thick, had a surface roughness Rz of 9.1 μm, had a circumferential thickness fluctuation width of 0.05 mm, and had a long length. Thickness fluctuation width in the direction 0.
An elastic member for a belt having a volume resistivity of 3 × 10 ¹¹ Ω · cm and a thickness of 03 mm was obtained, and a coating agent 3 and a coating agent 4 were applied thereto in the same manner as in Example 2 to obtain a belt. Table 2 shows the physical properties of this belt. Table 3 shows the results of image evaluation using this belt as the transfer conveyance belt 1 in FIG.

Comparative Example 6 A belt was obtained in the same manner as in Example 1, except that the coating agent 2 was applied so as to have a thickness of 0.3 μm. Table 2 shows the physical properties of this belt. Table 3 shows the results of image evaluation using this belt as the transfer conveyance belt 1 in FIG.

Comparative Example 7 A belt was obtained in the same manner as in Example 1, except that the coating agent 7 shown in Table 1 was used instead of the coating agent 1. Table 2 shows the physical properties of this belt. Table 3 shows the results of image evaluation using this belt as the transfer conveyance belt 1 in FIG.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

From the results of Tables 2 and 3, Examples 1-4
The belt is good in visual condition, the running property of the belt is good, and the fluctuation width of the belt surface potential is as small as 5 mV or less as shown in FIG. 6. The initial image and the image after passing 5,000 sheets were also good. On the other hand, a belt having an outermost layer containing conductive fine particles (carbon) (Comparative Examples 1, 2 and 2)
3) a belt in which the variation width of the thickness of the elastic member exceeds 0.1 mm (Comparative Example 4), and a belt in which the surface roughness Rz of the belt exceeds 8 μm because the surface roughness of the elastic member is large (Comparative Example 5) The belt surface potential of the belt whose outermost layer thickness is less than 0.5 μm (Comparative Example 6) and the belt whose carbon particle diameter added as the conductive fine particles to the resistance adjusting layer exceeds 500 nm (Comparative Example 7) are shown in FIG. As shown in FIG. 7, image density unevenness occurred even in the initial image, and this was further deteriorated after 5,000 sheets were passed.

[0050]

According to the first aspect of the present invention, a high voltage is applied from the back surface of the belt, and the toner image on the photosensitive member that comes into contact with the belt surface is formed on the paper existing between the belt and the photosensitive member. For example, in a transfer and conveyance belt that transfers the paper to a fixing device, the belt surface potential becomes uniform, and the toner image on the photoconductor is transferred without density unevenness.

According to the second and eighth aspects of the present invention, the releasability of the outermost layer is improved, no extra toner remains, and the image is not stained.

According to the third and fourth aspects of the present invention, the resistance of the entire belt can be maintained in a preferable state, and the belt surface potential can be made uniform.

According to the present invention, the high voltage applied to the back surface of the belt can be maintained at a preferable surface potential.

According to the present invention, the belt surface potential is maintained uniformly. According to the present invention, the contact width between the photoconductor and the belt is set in a preferable range.

According to the present invention, transfer omission does not occur.

[Brief description of the drawings]

FIG. 1 is a perspective view of a transfer conveyance belt 1 according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of the transfer conveyance belt 1.

FIG. 3 is a cross-sectional view of an exposure and development section of an electrophotographic apparatus using the transfer conveyance belt 1 of the present invention.

FIG. 4 is a side view of a traveling test device that measures the traveling property and surface potential of the transfer / conveying belt 1.

FIG. 5 is a side view for explaining the degree of elongation η of the belt 1;

FIG. 6 is a graph showing a fluctuation state of a belt surface potential in Example 1.

FIG. 7 is a graph showing a fluctuation state of a belt surface potential in Comparative Example 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transfer conveyance belt 2 Elastic member 3 Surface layer 4 Resistance adjustment layer 5 Outermost layer 11 Photoconductor 12 Exposure area 13 Development area 14 Transfer area 15 Cleaning area 21 Charging roller 23 Developing device 26 Developing roller 28 Paper (recording medium) 29 Cleaning blade Reference Signs List 30 static elimination means 41 driven roller 42 drive roller 46 paper feed roller 47 fixing device

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C08L 71/03 C08L 71/03 75/04 75/04 (72) Inventor Yosuke Matsui 3 Meiwadori, Hyogo-ku, Kobe-shi, Hyogo No.2-15, Bando Chemical Co., Ltd. F term (reference) 2H032 AA05 BA18 4J002 AC071 AC091 CH021 CH041 CK021 DA016 DA066 DE096 FD116 GF00 GM01 GQ02 GS00

Claims (9)

[Claims] 1. A transfer / transport belt for an electrophotographic apparatus having a surface layer on an elastic member and applying a voltage from the elastic member side, wherein the surface layer comprises a resistance adjustment layer on the elastic member side and an outermost layer on the surface side. A transfer conveying belt for an electrophotographic apparatus, wherein the outermost layer does not contain conductive fine particles, and the outermost layer has a volume resistivity higher than that of the resistance adjusting layer. 2. The transfer conveyance belt for an electrophotographic apparatus according to claim 1, wherein said outermost layer is made of a polymer containing a fluorine group. 3. The transfer conveyance belt for an electrophotographic apparatus according to claim 1, wherein the outermost layer has a thickness of 0.5 to 70 μm. 4. The electrophotography according to claim 1, wherein when the conductive fine particles are added to the resistance adjusting layer, the conductive fine particles are conductive carbon having a particle size of 30 to 500 nm. Transfer conveyance belt for equipment. 5. The electroconductive member according to claim 1, wherein said elastic member is made of a chloropyrene rubber, a nitrile rubber, a urethane, an epichlorohydrin, or a copolymer containing epichlorohydrin-ethylene oxide as a main component or a mixture of two or more of them. Volume specific resistance of 10 ⁶ to
2. The method according to claim 1, wherein the resistance is adjusted to 10 ¹² Ω · cm.
5. The transfer / conveying belt for an electrophotographic apparatus according to any one of items 1 to 4. 6. The electrophotographic apparatus according to claim 1, wherein the elastic member has a thickness of 0.2 to 2 mm and a variation width of the thickness is 0.1 mm or less. Transfer conveyor belt. 7. The transfer / conveying belt for an electrophotographic apparatus according to claim 1, wherein the belt elongation η is 8% or less. 8. The transfer conveyance belt for an electrophotographic apparatus according to claim 1, wherein the surface roughness Rz of the belt is 8 μm or less. 9. The transfer conveyance belt for an electrophotographic apparatus according to claim 1, wherein a water contact angle θ of the belt surface is 90 ° or more.