JPH08314233A - Film used for electrostatic charging member for electrophotography and transfer member - Google Patents

Abstract

PURPOSE: To provide a film used for an electrostatic charging member for electrophotography having good smoothness and capable of satisfying a toner release property and a transfer member. CONSTITUTION: The film formed on the surfaces of the electrostatic charging member for electrophotography and the transfer member is a film formed by curing an epichlorhydrin-ethyene oxide copolymer and a polyester polyol or acryl polyol having good compatibility with this epichlorhydrin-ethyene oxide copolymer by an isocyanate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film used for a charging member and a transfer member for electrophotography, and more specifically, a film for a charging member (charging roller) of a photoconductor used for electrophotography and toner on paper. The coating used for the transfer member (transfer roller) for transfer, which has good smoothness and good toner releasability at the time of paper transfer. It is related.

[0002]

2. Description of the Related Art Conventionally, a corona charging method using a corona discharger has been used for charging and transferring a photoconductor used in electrophotography. However, the corona charge method is
There is a drawback that ozone that is harmful to the human body is generated during corona charging, and in recent years, there has been a demand for suppressing the generation of harmful ozone, and the contact charging method that generates extremely little ozone has attracted attention.

As is well known, the contact charging method is a method in which a conductive roller, a conductive brush or the like to which a voltage is applied is pressed against the surface of the photoconductor to charge the surface of the insulator. The roller type is widely used because it is inexpensive and can be charged with a low applied voltage and is easy to use.

This roller type is covered with a rubber having a resistance in the medium resistance region provided on the charging member and the transfer member, and further, in order to reduce the toner releasability and the friction resistance, the resistance in the medium resistance region is used. It is covered with a film with. The toner releasability is because the toner adheres to the charging member and the transfer member, so that the toner does not adhere, and the reduction in frictional resistance is a characteristic required for contacting the toner cleaning member.

[0005]

Conventionally, in a film used for a charging member and a transfer member for electrophotography, an epichlorohydrin-ethylene oxide copolymer is used as a conductive additive in order to obtain a film in a medium resistance region. It is often used. Usually, this film has a poor toner releasing property, and therefore is mixed with a fluorine-based paint to impart toner releasing property and slipperiness.

However, since the epichlorohydrin-ethylene oxide copolymer and the fluorine-based coating material have poor compatibility with each other, they have the drawback that phase separation occurs during film formation and a smooth surface cannot be obtained.

Further, there is a drawback that the abrasion resistance is low because the components in the film are not compatible with each other.

The present invention has been made in view of the above, and an object of the present invention is to provide a film used for a charging member and a transfer member for electrophotography, which has good smoothness and satisfactory toner releasability. And

[0009]

SUMMARY OF THE INVENTION The first invention has been made in view of the above-mentioned problems, and the first invention is a film used for a charging member and a transfer member for electrophotography, wherein an epichlorohydrin-ethylene oxide copolymer is used. A film used for a charging member and a transfer member for electrophotography, which is a film obtained by curing a polymer and a polyester polyol or an acrylic polyol having good compatibility with the epichlorohydrin-ethylene oxide copolymer with an isocyanate. is there.

A second aspect of the present invention is the film used for the charging member and transfer member of the first aspect, wherein the epichlorohydrin-ethylene oxide copolymer amount is 40 wt.
% Or less, it is a film used for a charging member and a transfer member used in electrophotography.

The third invention is characterized in that the film used for the charging member and the transfer member of the first and second inventions contains fluorine resin particles, a fluorine resin oligomer or a solvent-soluble fluorine resin. A coating used for a charging member and a transfer member for electrophotography.

A fourth aspect of the present invention is a charging member for electrophotography, characterized in that the film used in the charging member and transfer member of the first to third inventions contains a low molecular weight silicone oil. It is a film used for transfer members.

A fifth aspect of the present invention is a charging member for electrophotography, comprising a coating used for the charging member and transfer member according to the first to third aspects, wherein the surface of the coating is polished. And a film used for a transfer member.

[0014]

According to the first aspect of the present invention, as a film used for a charging member and a transfer member for electrophotography, an epichlorohydrin-ethylene oxide copolymer and a polyester polyol or acryl having good compatibility with the epichlorohydrin-ethylene oxide copolymer. The surface of the coating is made smooth by forming a coating obtained by curing the polyol and isocyanate.

A second aspect of the present invention is the coating used for the electrophotographic charging member and transfer member according to the first aspect of the present invention.
By setting the amount of the epichlorohydrin-ethylene oxide copolymer to 40 wt% or less, a film having high abrasion resistance can be obtained, so that the abrasion resistance of the film when contacted with a contact brush or a toner cleaning member can be improved. it can.

A third aspect of the present invention is a fluororesin particle, a fluororesin oligomer, or a solvent-soluble fluororesin in the coating used for the electrophotographic charging member and transfer member of the first or second aspect. By including the toner, it is possible to reduce the toner adhesion and prevent the transferred image from being contaminated.

The fourth and fifth inventions are the first, second or third inventions.
In the film used for the charging member and transfer member for electrophotography of the invention of claim 1, by including a low molecular weight silicone oil and polishing the surface of the film, the frictional force with the toner cleaning member can be reduced. .

[0018]

EXAMPLES Examples of coatings used for the electrophotographic charging member and transfer member according to the present invention will be described below.

In the first embodiment, the coating used for the charging member (charging roller) and the transfer member (transfer roller) for electrophotography has a volume resistivity of 5 × 10 ⁹ Ω · cm and a thickness of 6 mm. Is a film formed by curing an epichlorohydrin-ethylene oxide copolymer and a polyester polyol or acrylic polyol having good compatibility with the epichlorohydrin-ethylene oxide copolymer with an isocyanate on the surface of the roller coated with the rubber.

The film can be formed by a known method such as dipping, spraying or roll coater.

The film used for the charging member and transfer member for electrophotography of the second embodiment has the epichlorohydrin-ethylene oxide copolymer amount of 40 wt% or less in the first embodiment. is there.

The coating used in the charging member and the transfer member for electrophotography of the third embodiment is the same as the coating in the first or second embodiment, but it is a fluorine resin particle, a fluorine resin oligomer, or a solvent-soluble fluorine. It contains a resin.

The coatings used for the electrophotographic charging member and transfer member of the fourth embodiment are the coatings of the first to third embodiments containing low molecular weight silicone oil.

The coating used in the charging member and transfer member for electrophotography of the fifth embodiment is formed by polishing the surface of the coating after the coating of the first to third embodiments is formed. It has improved smoothness.

Next, the films of the above-mentioned examples were obtained experimentally, and the details thereof will be described below.

First, Table 1 shows the results of the examination of the compatibility with the epichlorohydrin-ethylene oxide copolymer and the surface roughness after film formation.

In this experiment, an epichlorohydrin-ethylene oxide copolymer (for example, ethylene oxide 50 mol%) was mixed with various polyols such as polyester polyol or acrylic polyol to form a film.

Further, 30 w of epichlorohydrin-ethylene oxide copolymer (ethylene oxide 50 mol%) was added to a mixture of the above various polyols and isocyanate (curing agent) so that NCO / OH = 1/1.
t% mixed. Further, this product is diluted with a solvent (xylene) so that the solid content concentration becomes 10%, applied on the roller surface by spraying, and then crosslinked at about 100 ° C. to form a film. . The surface roughness of the film formed on the roller surface shown in Table 1 is the result of measurement with a stylus type surface roughness meter.

[0029]

[Table 1]

As is clear from Table 1, it was found that the compatibility was good in Examples 1 and 3, and the coating surface roughness was smooth in Examples 1 and 2. From these results, there is a correlation between the compatibility and the surface roughness, and when the epichlorohydrin-ethylene oxide copolymer and the one with good compatibility are mixed, a good surface roughness (smoothness) of 1 μm or less is obtained. I know you can get it. This is because in the case of a resin that has good compatibility with the conductivity-imparting agent epichlorohydrin-ethylene oxide copolymer, the resin does not separate in the film and the epichlorohydrin-ethylene oxide copolymer is clean at the molecular level. It is presumed that they were mixed.

The compatibility is 50% of each polyol and epichlorohydrin-ethylene oxide copolymer.
It was judged by the presence or absence of phase separation when the toluene solution was mixed at a ratio of 1: 1 and then allowed to stand for 30 minutes.

Next, Table 2 shows the experimental results on the abrasion resistance of the coating. A film was formed by varying the weight% of epichlorohydrin-ethylene oxide copolymer, and its abrasion resistance was investigated. The results shown in Table 2 are those obtained by forming a film by mixing epichlorohydrin-ethylene oxide copolymer (ethylene oxide 60 mol%) and isocyanate with the acrylic polyol A of Example 1 having good compatibility. Is. The roller to which the film was attached was incorporated into an experimental machine and a paper passing test was conducted. A toner cleaning member is in contact with the experimental machine.

[0033]

[Table 2]

As is clear from the results in Table 2, the epichlorohydrin-ethylene oxide copolymer was 40 wt%.
It was found that the following coatings had a step difference of 2 μm or less and were excellent in abrasion resistance. According to this result, 40 wt% of epichlorohydrin-ethylene oxide copolymer was used.
It can be said that a coating film having good abrasion resistance can be obtained by adjusting the content to be not more than%.

It is also considered that this is because as the amount of the epichlorohydrin-ethylene oxide copolymer increases, the steric hindrance of cross-linking occurs and the strength of the film decreases.
The abrasion resistance was measured by measuring the level difference between the contact portion and the non-contact portion of the toner cleaning member after 10K running with a stylus type surface roughness meter.

Next, Table 3 shows the relationship between the toner releasability-providing agent used for the film and the toner releasability.

[0037]

[Table 3]

As is apparent from Table 3, a roller having a film formed by adding various additives to the film of Example 9 in an amount of 10 wt% was prepared and incorporated in an experimental machine to evaluate the toner releasability. As a result, it was found that the fluororesin particles of Example 9, the fluororesin oligomer of Example 10, and the solvent-soluble fluororesin of Example 11 were good.

Therefore, it can be said that high toner releasability can be obtained by adding the fluororesin particles, the fluororesin oligomer, and the soluble fluororesin to the film. It is considered that this is because the fluorine resin having a good toner releasing property is arranged on the surface. On the other hand, the toner releasability imparting agent having the worst releasability is
No. 4 is a fluorine-based surfactant, and it is considered that the fluorine releasing groups are arranged on the surface, but the toner releasability deteriorates because the toner electrostatically adsorbs the toner.

Regarding the toner adhesion, the roller surface after 10K lining was visually inspected for stains on the adhesive tape during cleaning with the adhesive tape.

Next, the results of Table 4 show the effect by polishing, comparing the roller surface with and without polishing, and the fluorine resin particles (10
wt%) and the low molecular weight silicone oil of Example 15 (1 wt%) were added, and the relationship with friction was examined by the rotational torque.

In the film of Example 9, the roller surface on which this film was formed was pressed against a cloth having an abrasive fixed on the surface thereof, and the roller surface was polished to prepare an experiment. The rollers formed with these coatings were incorporated in an experimental machine and evaluated by the torque when driving the rollers.

[0043]

[Table 4]

As is clear from the results of this experiment, Example 15
It was found that the low torque silicone oil added and the roller surface polished in Example 16 had a rotation torque of 1.2 Kg, and that good results were obtained as compared with the others. It is considered that this is because in the case of a low molecular weight silicone oil, a small amount of oil deposited on the surface has a sliding effect. Further, it is considered that when abraded, a confidential skin layer is obtained on the surface of the film, so that the frictional resistance of the abutting member decreases.

With respect to the rotational torque, a tester in which the same contact member as that incorporated in the experimental machine was set was manufactured, and the starting value when the roller was rotated was read with a torque gauge. Further, the low frictional resistance of the coating means that a motor having a small rotational torque can be selected when the roller is incorporated into a machine.

Further, although it is clear that the above-mentioned conditions are used as examples in the method for producing a film, it is clear that the method can be carried out under various known conditions without being limited to these conditions.

[0047]

As described above, the present invention has the following advantages.

(1) The coating according to claim 1 has an advantage that a smooth coating surface can be obtained. Further, since a smooth coating surface can be obtained, a transfer image without unevenness can be obtained, and the frictional force with the cleaning member can be reduced, so that the rotational torque of the motor can be reduced.

(2) The coating according to claim 2 has the further advantage that a coating having high abrasion resistance can be obtained, and the durability of the charging roller and the transfer roller can be improved.

(3) The coating according to claim 3 has the further advantage that a coating having a characteristic that toner is hard to adhere can be obtained, and that the surface of the photoconductor is less likely to be contaminated. At the same time, it has the effect of preventing contamination of the transferred image.

(4) According to the coatings of claims 4 and 5, there is an advantage that a coating having a small frictional force with the cleaning member can be obtained, and a motor having a small rotating torque can be used.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Jun Aoto 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh (72) Masahide Yamashita 1-3-6 Nakamagome, Ota-ku, Tokyo Share Company Ricoh

Claims (5)

[Claims] 1. A film used for a charging member and a transfer member for electrophotography, which comprises an epichlorohydrin-ethylene oxide copolymer and a polyester polyol or an acrylic polyol having good compatibility with the epichlorohydrin-ethylene oxide copolymer. A film used for a charging member and a transfer member for electrophotography, which is a film cured with isocyanate. 2. The film used for the charging member and the transfer member according to claim 1, wherein the epichlorohydrin-containing film is used.
A film used for a charging member and a transfer member used in electrophotography, wherein the amount of the ethylene oxide copolymer is 40 wt% or less. 3. A film for use in the charging member and the transfer member according to claim 1 or 2, wherein the film contains fluororesin particles, fluororesin oligomers or solvent-soluble fluororesins. Film used for charging member and transfer member of. 4. The coating used for the charging member and the transfer member according to claim 1, 2, or 3, which contains a low molecular weight silicone oil, and is used for the charging member and the transfer member for electrophotography. A film that can be used. 5. A coating used for the charging member and the transfer member according to claim 1, 2 or 3, wherein the surface of the coating is polished. The film used.