WO2005059657A1

WO2005059657A1 - Conductive rubber roller

Info

Publication number: WO2005059657A1
Application number: PCT/JP2004/015044
Authority: WO
Inventors: Akihito Funakoshi
Original assignee: Yamauchi Corporation
Priority date: 2003-12-16
Filing date: 2004-10-13
Publication date: 2005-06-30
Also published as: JP2005181390A; CN1867870A

Abstract

A conductive rubber roller capable of inhibiting the attachment of toner to roller parts while retaining desirable electrical properties is provided without pass through complex production procedure. There is provided a conductive rubber roller characterized in that at least a roller surface consists of a rubber composition comprising 100 parts by mass of rubber component and 0.01 to 20 parts by mass of plasticizer wherein the difference between solubility parameter (SP value) (A) of main constituent of the rubber component and solubility parameter (SP value) (B) of main constituent of the plasticizer, (A)-(B), is 0.9 or greater. It is preferred that the rubber composition be a solid rubber or sponge rubber and that the main constituent of the rubber component be an epichlorohydrin rubber. At least one component whose solubility parameter (SP value) (B) falls within the range of 5.0 to 8.5 can appropriately be used as the plasticizer.

Description

Specification

Conductive rubber roller

Technical field

The present invention relates to a conductive rubber roller suitably used for a charging roller, a developing roller, a transfer roller and the like in an electrophotographic apparatus such as a copying machine and a printer. Background art

[0002] In electrophotographic devices such as copiers and printers, conductive rollers are used for paper feed rollers and the like. Toner particles adhere to the conductive roller over a long period of use and cause contamination of the output paper.Therefore, as a method of preventing toner from adhering to the roller surface, the rubber surface is treated by UV treatment or the like. Countermeasures such as reforming or reforming into two or more layers by resin coating etc. are generally taken.

[0003] For example, Patent Document 1 discloses that in a charging roller having two layers, an elastic layer and a surface layer covering the surface of the elastic layer, the surface average roughness of the surface layer is made smaller than the surface average roughness of the elastic layer. Accordingly, there has been proposed a method of improving the non-adhesiveness between the photosensitive member and the toner and the roller and improving the durability. However, in this method, since the reforming is performed by using two or more roller portions, the process is inevitably complicated and the cost is increased. In addition, when the difference in conductivity between the rubber layer and the resin coating layer is large, it is difficult to control the resistance value.

[0004] On the other hand, for example, in Patent Document 2, a transfer member is provided with an elastic layer formed using urethane rubber or a rubber material, and the surface of the elastic layer is subjected to heat treatment, UV treatment, plasma treatment, ion beam, electron beam, and the like. An image forming apparatus characterized by being modified by post-processing using a line or the like is disclosed. By these post-treatments, an active layer (such as a cross-linked layer) is formed on the rubber surface, and the molecular structure of the surface becomes dense. Therefore, the surface energy is reduced, the releasability is improved, and the amount of toner and paper dust attached can be reduced.

[0005] However, when the surface is modified by UV treatment or the like, there is a problem that a difference in hardness or electrical characteristics occurs between the rubber surface and the rubber interior due to a change in a functional group on the modified rubber surface. . Patent Document 1: Japanese Patent Application Laid-Open No. 7-049605

Patent Document 2: JP-A-11-109769

Disclosure of the invention

Problems to be solved by the invention

[0006] The present invention solves the above-mentioned problems, and provides a conductive rubber roller capable of suppressing adhesion of a toner to a roller portion while maintaining good electrical characteristics without performing a complicated manufacturing process. The purpose is to do.

Means for solving the problem

[0007] The present invention is formed of a rubber composition containing at least 100 parts by mass of a rubber component of a roller surface force and 0.01 to 20 parts by mass of a plasticizer. The difference between (SP value) (A) and the solubility parameter (SP value) of the main component in plasticizer (SP value) (B) When (A)-(B) is 0.9 or more ((A)-(B) ≥0.9) The present invention relates to a conductive rubber roller. It is particularly preferable that the main component in the rubber component is epichlorohydrin rubber.

In the following, “SP value (A)” is the solubility parameter of the main component in the rubber component, and “SP value (B)” is the solubility parameter of the main component in the plasticizer, “SP value “(A) −SP value (B)” means the difference obtained by subtracting the SP value (B) from the SP value (A).

[0009] In the present invention, the "main component" in the rubber component or the plasticizer refers to a component that accounts for 50% by mass or more of the entire rubber component or the entire plasticizer. For example, when 50% by mass of each of the two components is mixed with the rubber component or the plasticizer, at least one combination having an SP value (A) —SP value (B) of 0.9 or more is used. You only need to have one.

[0010] The SP value can be considered as one index indicating molecular polarity, and a molecule having a large SP value can be generally regarded as having a large polarity. In the present invention, a conductive roller capable of suppressing toner adhesion can be obtained by using a rubber composition in which the relationship between the SP value of the rubber component and the plasticizer is adjusted within a certain range.

[0011] As the rubber composition of the present invention, it is preferable to use solid rubber or sponge rubber. Further, the content of the plasticizer is more preferably set in the range of 0.1 to 2.0 parts by mass. In the plasticizer of the present invention, the SP value (B) is preferably in the range of 5.0 to 8.5, more preferably 7.5 or less, and particularly preferably 6.5 or more. preferable.

The invention's effect

[0013] According to the present invention, by adjusting the relationship between the SP value of the rubber component and the plasticizer, and applying the rubber composition having reduced surface energy to at least the surface of the rubber roller, the adhesion of the toner to the roller surface can be prevented. A conductive rubber roller that can be effectively suppressed can be manufactured without going through a complicated process.

Brief Description of Drawings

FIG. 1 is a cross-sectional view showing a structure of a conductive roller of the present invention.

Explanation of symbols

[0015] 1 core metal part, 2 rubber part.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a cross-sectional view showing the structure of the conductive roller of the present invention. The conductive rubber porter of the present invention is configured by covering a cored metal part 1 with a rubber part 2.

[0017] The rubber composition used in the conductive rubber roller of the present invention has an SP value (A)-an SP value (

It is characterized in that the relationship between the SP value of the rubber component and the plasticizer is adjusted so that B) becomes 0.9 or more.

[0018] The SP value in the present invention is obtained by a small expression,

σ = ∑Fi / V = p Fi / M

(However, Fi: molar suction force constant, V: molar volume,: density, M: molecular weight)

It is represented by

[0019] Since the SP value can be mainly regarded as an index indicating the polarity of the molecule, molecules having similar SP values generally show high compatibility. For the rubber component used for the conductive rubber roller, it is preferable to use a rubber component having an SP value equal to or higher than a certain value in order to secure sufficient physical strength. This contributes to toner adhesion. Here, when a plasticizer having an SP value sufficiently smaller than that of the rubber component is added, the plasticizer imparts flexibility to the rubber composition and improves the operation stability of the rubber roller. By reducing the surface energy, the toner adhesion to the roller surface can be suppressed, and the performance as a rubber roller can be improved.

[0020] The conductive rubber roller of the present invention is characterized in that a plasticizer having a difference in SP value from a rubber component within a specific range is blended in order to suppress toner adhesion. Therefore, since the roller surface does not need to be chemically modified, the rubber portion of the conductive rubber roller has excellent electrical properties without sacrificing the conductivity and physical properties. La is obtained.

[0021] The conductive rubber roller of the present invention may be composed of a single layer or multiple layers, and at least the SP value of the main component of the rubber component and the plasticizer is specified on the surface of the rubber roller. It is only necessary to satisfy the relationship. However, from the viewpoint of obtaining good conductivity, it is advantageous that the inside of the roller and the surface of the roller have the same composition, and it is more preferable that the roller has a single layer. In the case of being composed of multiple layers, it is sufficient that at least the layer constituting the roller surface is composed of a rubber composition having an SP value (A) -SP value (B) of 0.9 or more.

In the present invention, the relationship between the SP value (A) —the SP value between the rubber component and the plasticizer is set so that the SP value (B) becomes 0.9 or more. In order for the rubber component to have sufficient physical strength, it is necessary to use a material with an SP value of at least a certain value.If the difference between the SP value of the rubber component and the plasticizer is 0.9 or more, the physical strength A rubber component having excellent surface energy and a plasticizer having an excellent surface energy reducing effect are combined, and the rubber roller has a good toner adhesion suppressing effect. Further, in this case, it is possible to prevent the compatibility between the rubber component and the plasticizer from becoming too high, and to control the plasticizer to be dispersed in the rubber composition while maintaining an appropriate aggregation form.

. Therefore, the plasticizer also exists on the rubber roller surface in a dispersion size equal to or greater than a certain value, and a maximum amount of surface energy can be reduced with a small amount of the plasticizer.

In the present invention, when the SP value (A) —the SP value (B) is less than 0.9 and 0 or more, a large amount of a plasticizer is added in order to obtain a desired surface energy reduction effect. There is a need to. It is not preferable to add a large amount of plasticizer by applying a large amount of plasticizer because the plasticizer may bleed to the surface when the rubber roller is used, thereby causing contamination or the like.

On the other hand, when the SP value (A) —the SP value (B) is smaller than 0, the force required to use a rubber having an SP value smaller than that of a plasticizer generally used in the rubber industry is obtained. Rubber like Does not have the characteristics required for use in the rubber portion of the rubber roller, such as physical strength and heat resistance, and is not suitable for use in the rubber portion.

From the above, when the SP value (A) —the SP value (B) is 0.9 or more, the properties of the rubber component and the main component of the plasticizer are sufficiently reflected in the entire rubber composition.

[0026] SP value (A)-SP value (B) is more preferably 0.9 or more, and more preferably 1.5 or more. However, if the difference between the SP values is too large, the compatibility is poor. Since the bleeding of the plasticizer in the rubber composition power between the rubber component and the plasticizer in the production tends to occur easily, for example, the SP value (A) -SP value (B) is 4.0 or less, especially 3.0 or less. It is preferable to set

The rubber component used in the present invention includes rubber having ionic conductivity such as epichlorohydrin rubber, urethane rubber, nitrile butadiene rubber, acrylic rubber, chloroprene rubber, fluorine rubber, -tolyl rubber, norbornene rubber, and the like. In addition, rubbers such as natural rubber (NR), butadiene rubber, isoprene rubber, acrylonitrile butadiene rubber (NBR), ethylene propylene-gen copolymer rubber (EPDM), butyl rubber, silicone rubber, etc. can be used alone or as a mixture of two or more. Can be used as Of these, epichlorohydrin rubber is particularly preferred in that it has good conductivity and physical properties, and a rubber component containing epichlorohydrin rubber as a main component, particularly, epichlorohydrin rubber and acrylonitrile butadiene rubber ( rubber components NBR) and was blended at 50 wt ^_0/0 exhibits excellent conductivity and physical properties.

[0028] The SP value (A) in the rubber component of the present invention is not particularly limited, but is preferably 7.0 or more and 10.0 or less. Among them, when the SP value (A) is 7.5 or more, more preferably 8.0 or more, especially 8.5 or more, the rubber component has good physical strength, conductivity and heat resistance, and 9.5 or less. If the value is 9.0 or less, the curability and operation stability are good.

[0029] Examples of the plasticizer of the present invention include paraffinic, naphthenic, and aromatic process oils as petroleum softeners, castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, and the like as plant softeners. Preferable oils such as rapeseed oil, peanut oil, wood wax, rosin, pine oil, tall oil, etc., as well as phthalate, adipate, sebacate, phosphate, polyester and polyester plasticizers are preferably used. These can be used alone or as a combination of two or more.

[0030] The plasticizer is used in an amount of 0.01 to 20 parts by mass, particularly 0.1 to 2.0 parts by mass, per 100 parts by mass of the rubber component. It is blended so that it may be in the range of. If the compounding amount is 0.01 parts by mass or more, the effect of preventing the adhesion of the toner due to the presence of the plasticizer is obtained to a desired degree. There is little danger of dripping or deterioration of the physical properties of the rubber part.

[0031] In the present invention, a plasticizer having an SP value (B) in the range of 5.0 to 8.5 is used. When the SP value (B) is 5.0 or more, it is a force capable of preventing deterioration of physical properties of a rubber portion and bleeding of a plasticizer. When the SP value (B) is 8.5 or less, a sufficient effect of reducing the surface energy is obtained, so that the effect of suppressing toner adhesion is excellent. Among them, it is particularly preferable that the SP value is 6.5 or more, and it is particularly preferable that the SP value is 7.5 or less.

[0032] The SP value of the rubber component and the plasticizer may be appropriately selected according to the required characteristics according to the application of the conductive rubber roller.

[0033] Specific examples of preferred plasticizers include a paraffinic petroleum softener having an SP value of about 6 to 8, or a naphthenic petroleum softener having an SP value of about 7.5 to 8.5. And silicone oil having an SP value of about 0.3. The SP values of these softeners are described, for example, in "Basics of Rubber Technology" (edited by The Rubber Association of Japan). As a combination of a rubber component and a plasticizer, these plasticizers may be used alone or in the form of a mixture of two or more types to be mixed with an epichlorohydrin rubber having an SP value of about 8.8-9.5. Is particularly preferred.

[0034] In addition to the rubber component and the plasticizer described above, the rubber composition used in the present invention may appropriately contain compounding components generally used in the production of rubber products as described below.

Examples of the vulcanizing agent include sulfur, organic compounds such as sulfur, tetraalkylthiuram disulfide, morpholine disulfide, and alkyl phenol disulfide; metal compounds such as magnesium oxide; p-quinone-oxime; There are oximes such as dibenzoyl quinone dioxime, peroxides such as dicumyl peroxide and benzoyl peroxide, sulfur chloride, selenium, tellurium, etc., which are inexpensive and easily available, and have a vulcanizing effect. Sulfur is preferred because it is sufficiently large and has excellent abrasion resistance on the rubber roller surface

[0036] Examples of the vulcanization accelerator include dibenzothiazolyl disulfide (DM) and 2 mercaptoben. Thiazoles such as zothiazole (D) and zinc 2-mercaptobenzothiazole (MZ); sulfenamides such as diisopropylsulfenamide (DIBS) and cyclohexylsulfenamide (CZ); tetramethyltyrium disulfide (TT), tetraethylthiuram-disulfide (TET), thiurams such as dipentamethylenethiuram-tetrasulfide (TRA), dimethyldithiocarbamate zinc salt (PZ), getyldithiocarbamate zinc salt (EZ) Dithionates, guanidines, thiopereas, aldehyde ammoniums, xanthates and the like. Thiazoles promote the reaction between the rubber component and the vulcanizing agent, shorten vulcanization time, lower the vulcanization temperature, reduce the amount of sulfur, and improve the breaking strength and abrasion resistance of rubber rollers. Especially preferred is DM. Further, sulfenamides are preferred, and CZ is particularly preferred because sulfonamides are preferred because thiazoles have a slower scorch and a faster rise of vulcanization.

[0037] Examples of the vulcanization accelerating aid include metal oxides such as zinc white and fatty acids such as zinc stearate and oleic acid.

[0038] In addition, antioxidants such as amines and phenols, carbon, silica, clay, and cork

In addition to fillers such as talc, calcium carbonate, dibasic phosphite (DLP), basic magnesium carbonate, and alumina, a softener, a reinforcing agent, and the like can be appropriately compounded.

[0039] The rubber composition used in the present invention may be prepared as a solid rubber (hard rubber) and used for the rubber portion of the conductive rubber roller, or may be prepared and used as sponge rubber. A rubber roller using solid rubber has such advantages as being excellent in mechanical strength and conductivity, while a rubber roller using sponge rubber has such an advantage that it is excellent in flexibility and particularly suitable for use as a transfer roller. Therefore, the properties of the rubber composition to be used may be appropriately selected according to the desired performance of the electrophotographic apparatus to which the conductive rubber roller of the present invention is applied.

[0040] The sponge rubber can be produced by adding a foaming agent and, if necessary, a foaming aid to the components of the rubber composition, and preferably vulcanizing and molding under closed conditions.

As the foaming agent, a chemical foaming agent is suitably used, and is classified into an organic type and an inorganic type. Organic blowing agents include azodicarbonamide (ADCA), azobisisobuty-tolyl (AIBN), and azoi conjugates such as norium azodicarboxylate (BaZ AC); G -Troso compounds such as rosopentamethylenetetramine (DPT), benzenesulfol-hydrazide (BSH), 4,4 oxybis (benzenesulfol-hydrazide) (OBSH), toluenesulfol-l-hydrazide (TSH), hydrazodicarbonamide (HDCA ) And the like. As the inorganic foaming agent, sodium bicarbonate (baking soda), ammonium bicarbonate, ammonium carbonate, sodium hydrogen carbonate and the like can be used. These may be used alone or in combination of two or more.

[0042] As the foaming auxiliary, an urea-based auxiliary or the like can be used in addition to an organic acid-based auxiliary such as salicylic acid. Among them, as the blowing agent for the epichlorohydrin rubber suitably used in the present invention, a -troso compound such as N, N, 1-dinitrosopentamethylenetetramine (DPT) is particularly preferable.

[0043] The rubber roller of the present invention can be manufactured, for example, by the following method. That is, the rubber component and the plasticizer among the compounding components of the rubber composition are first kneaded in a single machine, etc., and then the other compounding components are sequentially charged in the single machine and kneaded, and then kneaded. Extrusion molding. This is steam-vulcanized at 150 ° C. for 50 minutes under a load of, for example, 4 kgfZcm ² (3.926266 × 10 ⁵ Pa) to obtain a cylindrical rubber composition. The obtained rubber composition is inserted into a stainless steel cored bar, and the rubber surface is polished to produce the rubber roller of the present invention.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

(Manufacture of conductive rubber roller)

The compounding materials containing the compounding components shown in Table 1 were kneaded, formed into a tube by an extruder, and then vulcanized at 150 ° C for 50 minutes to obtain a rubber for a roller. This was inserted into a cored bar and polished to an outer diameter of 2 Omm to obtain a rubber roller.

[Table 1] Example Example Example Example Example Comparative example Comparative example

1 2 3 4 1 2 Tapping--Human * Lin (Note ¹⁾ 100 100 100 100 100 100 Roses oil 1 (Note 0.1 ― 2.0 ― ― ― Silicone oil (Note ³ ) ― 0.1 ― 2.0 ― ― Aloma system [] Ses oil (Note ⁴ ) ― ― ― ― 2.0 ―

20 20 20 20 20 20 Vulcanizing agent ( ^{; is>} 0.5 0.5 0.5 0.5 0.5 0.5 Vulcanization accelerator ^(ft7) 2.0 2.0 2.0 2.0 2.0 2.0 Blowing agent ^8> 5.0 5,0 5.0 5.0 5.0 5.0

Note 1: Epichlorohydrin rubber is “G3106” manufactured by Nippon Zeon (three types of copolymers of ethylene oxide, arylglycidyl ether, and epichlorohydrin, SP value = 9.4) It is.

Note 2: The paraffin-based process oil is "Diana Process Oil, PW-380" (SP value = 6.6) manufactured by Idemitsu Kosan Co., Ltd.

Note 3: Silicone oil is "KF96-50" (dimethyl silicone oil, SP value = 7.3) manufactured by Shin-Etsu Chemical Co., Ltd.

Note 4: The aroma-based process oil is "Diana Process Oil AH 16" (SP value = 9.0) manufactured by Idemitsu Kosan Co., Ltd.

Note 5: Carbon is thermal black.

Note 6: The vulcanizing agent is sulfur.

Note 7: The vulcanization accelerator is mercaptobenzothiazole (MBT).

Note 8: The foaming agent is “CellMike A” (N, N, dinitrosopentamethylenetetramamine (DPT)) manufactured by Sankyo Kasei.

(Evaluation of Toner Sticking Property)

The toner magenta was spread over the paper, and the rubber rollers obtained in Example 14 and Comparative Example 12 were rolled to uniformly adhere the toner to the rubber surface. After leaving the rubber roller in contact with an aluminum drum having a diameter of 30 mm at a temperature of 45 ° C. and a humidity of 90% for 2 weeks, the state of the toner attached to the rubber roller was visually observed. Table 2 shows the results.

[Table 2] Aluminum tram abutment Other than aluminum tram abutment

Example 1 〇 (no change) o (no change)

Example 2 〇 (no change) 〇 (no change)

Example 3 〇 (no change) O (no change)

Example 4 〇 (no change) 〇 (no change)

Comparative Example 1 X (occurrence of sticking) X (color fading)

Comparative Example 2 X (sticking) X (color fading)

[0050] In Comparative Examples 1 and 2, toner sticking was observed at the contact portion with the aluminum drum, and the color of the toner other than the contact portion was lightened. The toner was not firmly adhered to any part other than the aluminum drum contact part and the contact part.

From these results, it can be confirmed that the rubber roller of the present invention has significantly improved toner adhesion.

[0052] The embodiments and examples disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

Industrial applicability

The conductive rubber roller of the present invention is obtained by controlling the relationship between the solubility parameter (SP value) of the rubber component and the plasticizer, and effectively suppresses toner adhesion. Further, a rubber having a desired toner adhesion preventing effect can be easily obtained only by considering the compounding components of the rubber composition. Therefore, the rubber can be manufactured without a complicated process such as multilayering, and the cost can be reduced. But excellent.

Claims

The scope of the claims

[1] At least the roller surface force is formed of a rubber composition containing 100 parts by mass of a rubber component and 0.01 to 20 parts by mass of a plasticizer, and a solubility parameter (SP value) of a main component in the rubber component (SP value) ( A conductive rubber roller, wherein the difference (A)-(B) between A) and the solubility parameter (SP value) of the main component in the plasticizer (B) is 0.9 or more.

[2] The conductive rubber roller according to [1], wherein the rubber composition is a solid rubber.

3. The conductive rubber roller according to claim 1, wherein the rubber composition is sponge rubber.

4. The conductive rubber roller according to claim 1, wherein a main component of the rubber component is epichlorohydrin rubber.

[5] The plasticizer according to claim 1, wherein the solubility parameter (SP value) (B) is one or more of component strengths within a range of 5.0 to 8.5. Conductive rubber wax described