JP2006163042A - Semiconductive roller, process cartridge and electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductive roller which has a resin layer containing amino resin, and which has a JIS-A hardness of ≤40°, then, improved in toner electrification and deformation recovery. <P>SOLUTION: Regarding the semiconductive roller having an elastic layer around a shaft core body, and also, having at least the conductive resin layer on the outer periphery of the elastic layer, the resin layer contains the amino resin, and also, the JIS-A hardness of the semiconductor roller is ≥25° and ≤40°. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductive roller used in contact with a photoreceptor incorporated in an apparatus employing an electrophotographic system such as a copying machine, a printer or a facsimile receiver, a process cartridge using the same, and an electrophotographic apparatus It is.

An electrophotographic apparatus such as a copying machine, a facsimile machine, or a printer has a semiconductive region of 10 ³ to 10 ¹⁰ Ω in order to charge a photosensitive member or to visualize an electrostatic latent image. An elastic roller having a property (electric resistance) is generally used. For example, in a non-magnetic one-component contact development type electrophotographic apparatus, a developer (toner) is moved from a developing roller pressed against each other to a photosensitive member (drum) to visualize an electrostatic latent image and development is performed. Is done. The elastic roller used in such an electrophotographic apparatus has a semiconductive property in which a single or a plurality of resin layers are formed on a conductive rubber layer in order to make a semiconductive roller satisfying a higher level of required quality. Many rollers are used.

  The elastic roller used in such an electrophotographic apparatus is required to be easily deformed and excellent in deformation recovery because it is pressed against the photoreceptor with a predetermined contact width or carries the toner thinned by a blade or the like. is there.

Further, when used as a developing roller, the roller is required to have a stable toner charging property. For this reason, Patent Document 1 reports a method of using a resin having excellent charging characteristics such as melamine or urea resin for the resin layer. However, as a result of the examination of the invention described in Patent Document 1 by the present inventors, these resin components described in Patent Document 1 are highly reactive, and therefore increase the hardness of the resin layer, In some cases, the flexibility is not sufficient, and there are concerns about problems such as set performance (deformability recovery) and deterioration due to stress on the toner.
JP-A-9-146362

  The performance required for developing rollers used in electrophotographic systems, such as copiers, printers, and facsimile receivers, has become more advanced, and the stability required for higher image quality as described above. The compatibility between the toner chargeability and the deformation recovery property is particularly a problem. An object of the present invention is to provide a high-quality semiconductive roller excellent in toner chargeability and setting performance, or to provide a process cartridge and an electrophotographic apparatus using such a semiconductive roller. is there.

  According to one aspect of the present invention, in the semiconductive roller having an elastic layer around the shaft core and a conductive resin layer containing a cured product of a reactive amino resin on the outer periphery thereof, A semiconductive roller is characterized in that the conductive roller has a JIS-A hardness (JIS K6253: 1997) of 25 ° or more and 40 ° or less.

  The process cartridge and the electrophotographic apparatus according to the present invention further include a developing roller that carries toner in a state of being opposed to the photosensitive member that carries the latent image, and the developing roller applies the toner to the photosensitive member, thereby the latent image. The semiconductive roller is used as a developing roller in a process cartridge and an electrophotographic apparatus for visualizing the above.

  Hereinafter, the semiconductive roller according to the present invention will be described in detail based on an aspect in which it is used as a developing roller of an electrophotographic apparatus.

  As shown in FIGS. 1 and 2, the developing roller 1 that is a semiconductive mouthpiece according to the present invention has an elastic layer 3 fixed to the outer peripheral surface of a cylindrical or hollow cylindrical conductive shaft core 2. The elastic layer 3 is composed of a conductive member in which a conductive resin layer 4 is laminated on the outer peripheral surface. In FIG. 2, which is a cross-sectional view of the developing roller 1, this conductive resin surface layer is the outermost surface layer, but on the inner periphery of the elastic layer 3, between the elastic layer 3 and the resin layer 4, or on the outer periphery of the surface layer 4. Further, one or more elastic bodies or surface layers may be laminated.

The conductive resin layer of the developing roller contains a cured product of a reactive amino resin, and the developing roller has a JIS-A hardness (conforming to JIS K6253: 1997) of 25 ° or more and 40 ° or less. It is characterized by a certain point. A conventional roller member having an elastic layer containing a reactive amino resin has a very high hardness because a highly reactive component is used as a reactive species. However, according to the present invention, while using a cured product of a reactive amino resin excellent in charging characteristics, by suppressing the increase in hardness by controlling its reactivity, Therefore, it is possible to obtain a developing roller that can eliminate the concern.
Hereinafter, each component of the developing roller will be described in order.

(1) Regarding the conductive shaft core body 2;
The conductive shaft core 2 functions as an electrode and a support member of a conductive member. For example, a metal or alloy such as aluminum, copper alloy, stainless steel, iron plated with chromium, nickel or the like, synthetic It is made of a conductive material such as resin. The outer diameter of the conductive shaft base is usually in the range of 4 to 10 mm.

(2) Regarding the elastic layer 3;
The elastic layer 3 has an appropriate hardness and electric resistance so that the conductive member can be pressed against the surface of the member to be charged with an appropriate nip width or nip pressure to uniformly charge the surface of the member to be charged. This elastic layer is formed of a molded body of rubber material. As the raw material rubber, various rubbers conventionally used for conductive rubber rollers can be used. Specifically, ethylene-propylene-diene copolymer rubber (EPDM), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR). ), Rubbers such as fluorine rubber, silicone rubber, epichlorohydrin rubber, NBR hydride, polysulfide rubber, urethane rubber and the like can be used alone or in admixture of two or more. Among these, silicone rubber is particularly preferable from the viewpoint of setting performance and the like. Examples of the silicone rubber include polydimethylsiloxane, polymethyltrifluoropropylsiloxane, polymethylvinylsiloxane, polytrifluoropropylvinylsiloxane, polymethylphenylsiloxane, polyphenylvinylsiloxane, and copolymers of these polysiloxanes. The average degree of polymerization of these silicone rubbers is preferably in the range of 4000 to 16000. Further, the elastic layer preferably has a JIS-A hardness (based on JIS K6253: 1997) of 10 to 40 °.

In the rubber material, a conductive agent is an essential component, and various additives such as a nonconductive filler, a crosslinking agent, a catalyst, and a dispersion accelerator are appropriately blended.
Use of fine particles such as conductive metals such as graphite, carbon black, aluminum, copper and tin or conductive metal oxides such as zinc oxide, tin oxide, titanium oxide and antimony monoxide solid solution as the conductivity imparting agent Can do. Among these, carbon black can be obtained relatively easily and good chargeability can be obtained.

Non-conductive fillers include diatomaceous earth, silica, quartz powder, titanium oxide, zinc oxide, aluminosilicate, calcium carbonate and the like. As a crosslinking agent, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, dicumyl peroxide, t-butylperoxybenzoate, P-chlorobenzoylper Examples include oxides. The volume resistivity value of the elastic layer 3 is preferably in the range of 10 ³ to 10 ¹⁰ Ω · cm when a DC voltage of 100 V is applied. For example, when carbon black is used as the conductive agent, it is blended in an amount of 5 to 90 parts by mass with respect to the rubber material. Moreover, the thickness of an elastic layer should just exist in the range of 1.0-6.0 mm, and it is preferable that it exists in the range of 2.0-5.0 mm.

(3) Regarding the conductive resin layer 4;
The conductive resin layer 4 contains a cured product of a reactive amino resin. The term “reactive amino resin” as used herein refers to a “reactive amino resin” having a reactive group (amino group, imino group, methylol group, alkyl ether group, etc.), an amino group, an amide group. An amino resin capable of reacting with a carboxyl group, a hydroxyl group or the like, and specific examples include melamine resin, urea resin and guanamine resin having the reactive group. Among them, melamine resin is excellent in cross-linking property of the film and toner charging property and is particularly preferably used.

The reactive melamine resin and reactive guanamine resin used as a raw material for the cured melamine resin are full ether type and have a weight average polymerization degree of 1.8 or less in order to obtain a developing roller having a desired hardness. desirable. By using these, the content of imino-type, methylol-type melamine and melamine with high polymerization degree, that is, a high degree of self-condensation reaction and sufficient toner chargeability can be obtained. In this case, the hardness of the film is remarkably increased, and the film becomes low in flexibility and flexibility, and the problem that it is difficult to achieve both toner chargeability and deformation recovery can be solved.
Further, when a urea resin is used, it is desirable that the weight average degree of polymerization is 2.0 or less.

  As the cured product of the reactive amino resin that forms the resin layer, a cured product obtained by reacting the reactive amino resin alone can be used, but the reactive reaction with the reactive amino resin and other polyol components can be performed. It is desirable to use the cured product from the viewpoints of self-film reinforcement, film flexibility, and the like.

  The polyol component used at this time is particularly preferably one having a hydroxyl value of 60 or less. By using such a polyol component, it is possible to obtain a developing roller that suppresses an increase in the hardness of the film, has high flexibility and flexibility, excellent deformation recovery, and excellent charging performance. In this way, when a reactive amino resin and a polyol having a hydroxyl value of 60 or less are reacted to obtain a cured product, the reactive amino resin and the polyol having a hydroxyl value of 60 or less are the flexibility of the resulting cured product, Considering flexibility, it is preferable to react the polyol at a ratio of 90 to 10% by mass with respect to 10 to 60% by weight of the reactive amino resin. The polyol component used by reacting with the amino resin in the resin layer 4 is particularly preferably a urethane resin, a polyester resin, or a polyether resin from the viewpoint of self-film reinforcing property, toner charging property, and the like. The number average molecular weight of these resin components is preferably 3000 to 6000. One or more of urethane resins, polyester resins or polyether resins, and other modified resins can be mixed and used, and the development system can be selected appropriately according to the development system. The toner charge amount suitable for the toner can be obtained. In the curing reaction of the resin layer, a curing catalyst may be used depending on the required firing conditions.

  Carbon black may be added to the resin layer 4 in order to impart conductivity. The carbon black added to the resin layer is desirably 5 to 50 parts by mass with respect to 100 parts by mass of the resin forming the resin layer. Furthermore, the film thickness of the resin layer is desirably 1 to 100 μm. The average particle size and DBP oil absorption amount of the carbon black used in the present invention are not particularly limited, but from the viewpoint of membrane reinforcement and conductivity imparting, the average particle size is 10 to 50 nm and the DBP oil absorption amount is 50 to 150 ml / 100 g. It is preferable. In order to improve the adhesion between the elastic layer 3 and the resin layer 4, a silane coupling agent having an amino group may be added to the resin layer 4. Examples of silane coupling agents include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxy. Silane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, methylaminoethoxypropyl dialkoxysilane and the like can be mentioned.

  Fine particles may be added to the resin layer 4 in order to control the roughness of the roller surface. The fine particles for roughness control preferably have an average particle size of 8 to 30 μm. Moreover, it is preferable that the particle addition amount added to a resin layer is 1-50 mass parts with respect to 100 mass parts of resin solid content of a resin layer. Furthermore, polyurethane resin, polyester resin, polyether resin, polyamide resin, acrylic resin, polycarbonate resin, or the like can be used as a component of the fine particles for controlling roughness.

  Examples of the coating method of the resin layer 4 on the elastic layer include spraying, dipping, roll coating and the like, but dipping coating, that is, a dipping tank as described in JP-A-57-5047. The method of overflowing the paint from the upper end is simple and excellent in production stability as a method for forming the resin layer, and is generally used.

An example in which the semiconductive roller of the present invention is applied to a laser beam printer as a developing roller will be described below.

[Example 1]
As the shaft core body 2, a SUS core metal having been plated with nickel, and further applied and baked with an adhesive was used. Next, the shaft core 2 is placed in a mold, and a liquid silicone rubber material (45 parts by mass of a linear polydimethylsiloxane blocked with a terminal vinyl group with a viscosity of 9000 Pa · s at 25 ° C. and a viscosity at 25 ° C. of 40 Pa · s and a polysiloxane mixture comprising 55 parts by mass of a block polymer comprising a branched polysiloxane segment having one vinyl group and a linear oil segment having about 200 continuous bifunctional dimethylsiloxanes, An organosiloxane having two or more silicon-bonded hydrogen atoms in one molecule as a crosslinking agent and a platinum-based catalyst were added, and 0.2 parts by mass of silica powder and 35 parts by mass of carbon black were mixed as a heat resistance imparting agent. Addition type silicone rubber composition) was injected into the cavity formed in the mold. Subsequently, the mold was heated to cure and cure the silicone rubber. After cooling, the mold was removed, and the elastic layer 3 was provided on the outer periphery of the shaft core body 2. The elastic layer had a JIS-A hardness of 34 °.

  Next, 70 parts by mass of a polyol component (polyether polyurethane, Mn = 4000, OHV = 30), 30 parts by mass of a reactive melamine resin A (trade name: Nicalac MW-30, manufactured by Sanwa Chemical Co., Ltd.), carbon black (product) Name: Talker Black # 7360SB, manufactured by Tokai Carbon Co., Ltd., 10 parts by mass, resin particles (trade name: MX1500H, manufactured by Soken Chemical Co., Ltd.), 10 parts by mass, and alkylbenzene sulfonic acid catalyst, 1 part by mass, have a total solid content ratio of 30%. Thus, it melt | dissolved in MEK, mixed, and it disperse | distributed uniformly with the sand mill, and obtained the dispersion liquid for resin layer formation. Next, this dispersion was dip-coated, dried, and heat-treated at 150 ° C. for 2 hours to provide a conductive resin layer on the outer periphery of the elastic layer, whereby the developing roller of Example 1 was obtained.

[Example 2]
The reactive melamine resin of Example 1 was changed to the reactive melamine resin B (trade name: Nicalak MW-22, manufactured by Sanwa Chemical Co., Ltd.). Otherwise in the same manner as in Example 1, the developing roller of Example 2 was obtained.

[Example 3]
The amount of the reactive melamine resin in Example 1 was changed to 60 parts by mass. Otherwise in the same manner as in Example 1, the developing roller of Example 3 was obtained.

[Example 4]
The melamine resin of Example 1 was changed to guanamine resin D (trade name: Nicalac BX-4000, manufactured by Sanwa Chemical Co., Ltd.). Otherwise in the same manner as in Example 1, the developing roller of Example 4 was obtained.

[Example 5]
The melamine resin of Example 1 was changed to urea resin E (trade name: Nicalac MX-202, manufactured by Sanwa Chemical Co., Ltd.). Otherwise in the same manner as in Example 1, the developing roller of Example 5 was obtained.

[Example 6]
The polyol component of Example 1 was changed to polyether polyurethane B (Mn = 3700, OHV = 60). Otherwise in the same manner as in Example 1, the developing roller of Example 6 was obtained.

[Example 7]
The polyol component of Example 1 was changed to polyester C (Mn = 3300, OHV = 45). Otherwise in the same manner as in Example 1, the developing roller of Example 7 was obtained.

[Example 8]
The polyol component of Example 1 was changed to polyether E (Mn = 3400, OHV = 30). Otherwise in the same manner as in Example 1, the developing roller of Example 8 was obtained.

[Comparative Example 1]
The melamine resin precursor of Example 1 was changed to an imino melamine resin precursor C (trade name: Nicalak MX-730, manufactured by Sanwa Chemical Co., Ltd.). Otherwise in the same manner as in Example 1, a developing roller of Comparative Example 1 was obtained.

[Comparative Example 2]
The amount of the melamine resin in Example 1 was changed to 70 parts by mass. Otherwise in the same manner as in Example 1, a developing roller of Comparative Example 2 was obtained.

[Comparative Example 3]
The amount of the melamine resin in Example 1 was changed to 5 parts by mass. Otherwise in the same manner as in Example 1, a developing roller of Comparative Example 3 was obtained.

[Comparative Example 4]
The polyol component of Example 1 was changed to polyester D (Mn = 3300, OHV = 80). Otherwise, the developing roller of Comparative Example 4 was obtained in the same manner as in Example 1.

The JIS-A hardness and toner charge amount of the developing roller produced as described above were measured. The obtained developing roller was loaded into a Canon laser beam printer, and the image density and setting performance were evaluated. A type A durometer (manufactured by Kobunshi Keiki Co., Ltd.) was used for measuring the JIS-A hardness (conforming to JIS K6253: 1997) of the roller.
The toner charge amount was measured by sucking the toner on the developing roller surface after image evaluation and collecting it on a Faraday gauge, and measuring the charge amount with an electrometer (trade name: KEITHLEY 616, manufactured by Toyo Corporation). Further, the charge amount per weight was determined from the collected weight at that time.

  3 and 4 show schematic configurations of a process cartridge and a laser beam printer including a developing roller according to an embodiment of the present invention. In this embodiment, the laser beam printer uses a non-magnetic one-component development system. The developing container 18 contains non-magnetic toner, and a developing roller 9 is installed in an opening facing the photoreceptor 1 so as to be in contact with the photoreceptor 1. As described above, the developing roller 9 has the elastic layer 3 and the resin layer 4 formed on the shaft core 2.

Evaluation of image density is performed using the above-described electrophotographic apparatus, outputting a solid image of non-magnetic one-component black toner, and using a reflection densitometer (trade name: GretagMacbeth RD918, manufactured by Macbeth Co., Ltd.). The points were measured and the average value was calculated. Moreover, the following criteria were evaluated based on the numerical value.
A: 14.0 or more B: 1.35 to 1.40
Δ: 1.30 to 1.35
X: 1.30 or less Evaluation of the set performance was performed by leaving the roller cores on the glass surface for 2 weeks at room temperature with a load of 1 kg each on the roller core, and then incorporating the roller into a process cartridge to output an image. The image evaluation was performed according to the following criteria.
◎: Press-contact trace is not seen on the image ○: Press-contact trace is seen very thin but does not affect the image △: Press-contact trace is seen and affects the image ×: Press-contact trace is clearly seen Tables 1 and 2 show the results beyond those affecting the above.

  The rollers of Examples 1 to 8 all showed good image density and set performance. On the other hand, Comparative Example 1 using an imino melamine precursor, Comparative Example 2 in which the amount of the melamine resin precursor used is 70 parts by mass, and Comparative Example 4 in which the polyol component has a hydroxyl value of 80 increase the hardness of the roller. , Set performance decreased. Further, Comparative Example 3 having a melamine resin content of 5 parts by mass has low toner chargeability and a low image density.

  As described above, in the developing roller having the elastic layer around the shaft core and at least the conductive resin layer disposed on the outer periphery thereof, the resin layer contains an amino resin, and the developing roller has a JIS-A hardness (JIS). By setting K6253) to 40 ° or less, a semiconductive roller excellent in toner charging property and deformation recovery property can be obtained.

The conceptual diagram of the semiconductive roller shown as an example of this invention. The conceptual diagram of the cross section of FIG. FIG. 3 is a conceptual diagram illustrating an example of a process cartridge according to the present invention. 1 is a conceptual diagram showing an example of an electrophotographic image forming apparatus of the present invention.

Explanation of symbols

1: semiconductive roller 2: shaft core 3: elastic layer 4: resin layer 5: photosensitive drum 6: charging device 7: laser beam 8: developing device 9: developing roller 10: toner supply roller 11: regulating blade 12: Toner 13: Transfer roller 14: Cleaning blade 15: Waste toner container 16: Fixing device 17: Paper 18: Developer container 19: End seal member

Claims (9)

In a semiconductive roller having an elastic layer around a shaft core and a conductive resin layer containing a cured product of a reactive amino resin on its outer periphery, the JIS-A hardness of the semiconductive roller ( A semiconductive roller, wherein JIS K6253: 1997) is 25 ° or more and 40 ° or less. The semiconductive roller according to claim 1, wherein the cured product is obtained by a reaction between a reactive amino resin and a polyol having a hydroxyl value of 60 or less. The semiconductive roller according to claim 2, wherein the cured product is obtained by reacting the polyol at a ratio of 90 to 40% by mass with respect to 10 to 60% by mass of the reactive amino resin. The semiconductive roller according to any one of claims 1 to 3, wherein the reactive amino resin is a full ether type melamine resin having a polymerization degree of 1.8 or less or a full ether type guanamine resin having a polymerization degree of 1.8 or less. . The semiconductive roller according to claim 1, wherein the reactive amino resin is a urea resin having a degree of polymerization of 2.0 or less. The semiconductive roller according to any one of claims 1 to 5, wherein the conductive resin layer further contains at least one resin selected from the group consisting of polyurethane, polyether, and polyester. The semiconductive roller according to any one of claims 1 to 6, wherein the semiconductive roller is a developing roller that carries toner and is used in contact with or close to a latent image carrier. 8. A process cartridge that is detachable from an electrophotographic apparatus, wherein the semiconductive roller according to claim 1 is used as a developing roller. A developing roller for use in an electrophotographic apparatus is provided that includes a developing roller that carries toner in a state of being opposed to a photoconductor that carries a latent image, and the developing roller visualizes the latent image by applying toner to the photoconductor. An electrophotographic apparatus comprising the semiconductive roller according to claim 1.

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