JP2003138045A - Surface treating liquid for electroconductive part, method of surface treating of electroconductive part, and electroconductive roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electroconductive roller improved in durability by an excellent treating method from the aspects of working environment, global environment protection, and quality control. SOLUTION: This electroconductive roller is equipped with an elastic layer 11 mainly comprising a rubber and an outer layer 13. The outer layer 13 is formed by coating on the elastic layer 11 a surface treating liquid which is prepared by dispersing and/or dissolving a polyisocyanate compound, in which a hydrophilic group is introduced and of which the isocyanate group is blocked, in a medium mainly composed of water, then heated and cured at a temperature not lower than 130 deg.C but not higher than 200 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment liquid for a conductive member, a method for treating the surface of a conductive member, and a conductive roller. More specifically, in consideration of work environment and global environment. However, the durability deterioration of a conductive member such as a conductive roller used in a conductive mechanism of an electrophotographic apparatus is improved.

[0002]

2. Description of the Related Art In a conductive mechanism in an electrophotographic device such as a printer, an electrophotographic copying machine, a facsimile device, an electrostatic recording device, etc., a charging roller for uniformly charging a photosensitive drum, and a toner carrying member. Various conductive members are used as represented by conductive rollers such as a toner supply roller, a developing roller for attaching toner to a photoconductor, and a transfer roller for transferring a toner image from a photoconductor to a sheet. Has been.

Such a conductive roller is generally composed of a columnar cored bar and an elastic layer composed of a vulcanized rubber layer which is concentrically laminated around the cored bar and is used for its application. Accordingly, various performances such as conductivity, non-staining property, low hardness and dimensional stability are required. Especially when used for a long time,
There is a problem of deterioration in durability that the image is deteriorated due to the phenomenon that residual toner particles and the like adhere to the surface of the conductive roller, and the same applies to other conductive members. Therefore, in order to prevent the deterioration of the durability, the surface of the elastic layer or the like has conventionally been subjected to a curing treatment with an isocyanate compound.

For example, in Japanese Patent Laid-Open No. 8-314233,
A coating used for a charging member and a transfer member for electrophotography has been proposed, and a treatment in which a polyester polyol or acrylic polyol having good compatibility with epichlorohydrin-ethylene oxide copolymer and isocyanate are dissolved in an organic solvent (xylene). The surface of the member is hardened with liquid. Further, in JP-A-9-265226, a charging member obtained by curing the surface of an elastic layer mainly composed of epichlorohydrin rubber on a conductive core metal with a treatment liquid prepared by dissolving an aromatic polyisocyanate in an organic solvent is disclosed. Proposed.

Further, in Japanese Patent Laid-Open No. 10-45953,
A conductive roll has been proposed in which the surface of an elastic layer made of rubber mainly composed of a copolymer of epichlorohydrin and ethylene oxide is cured by a treatment liquid in which an isocyanate-containing compound is dissolved in an organic solvent (ethyl acetate). Further, in JP-A-10-260568, the surface of an elastic layer mainly composed of epichlorohydrin rubber is treated with an isocyanurate body mainly composed of hexamethylene diisocyanate in an organic solvent, that is, toluene and xylene. A hardening-treated charging member has been proposed.

[0006]

However, the above-mentioned JP-A-8-314233 and JP-A-9-265226 have been proposed.
No. 10, JP-A-10-45953, and JP-A-10-2605.
In the conventional curing treatment with an isocyanate compound in No. 68, since the treatment liquid in which a large amount of highly reactive polyisocyanate is dissolved is used as described above, there are the following problems. In other words, the use of a large amount of polyisocyanate that is highly irritating to the human body together with a large amount of organic solvent results in a significantly bad working environment and also releases the solvent into the atmosphere. There is. In addition, there is a problem that it is difficult to control the quality of the treatment liquid because of the high reactivity of the polyisocyanate.

The present invention has been made in view of the above-mentioned problems, and is a surface treatment liquid for a conductive member and a conductive material which are excellent in quality controllability and improve the working environment while considering the preservation of the global environment. To provide a surface treatment method for a member, and
An object of the present invention is to provide a conductive roller that is excellent in durability deterioration and is also environmentally friendly.

[0008]

In order to solve the above problems, the present invention provides that a polyisocyanate compound having a hydrophilic group introduced therein is dispersed or / and dissolved in a medium mainly containing water. A surface treatment liquid for a characteristic conductive member is provided.

As a result of earnest research, the present inventors have made it possible to make the polyisocyanate compound water-soluble by introducing a hydrophilic group into the polyisocyanate compound, and thus it is harmless to the human body and the environment. Since it becomes possible to disperse and / or dissolve a polyisocyanate compound capable of imparting durability in a medium mainly composed of water, volatilization of the organic solvent is suppressed as compared with the conventional method using a large amount of the organic solvent. Therefore, it has been found that it is possible to obtain a surface treatment liquid for a conductive member which does not affect the working environment or the global environment and has excellent quality controllability.

The isocyanate group of the above-mentioned polyisocyanate compound is preferably blocked (masked). By blocking (masking) the isocyanate group, it is possible to suppress the reactivity of a large amount of isocyanate, which is difficult to control in quality due to its high reactivity, and facilitate the quality control of the surface treatment liquid. The blocked isocyanate group means that the isocyanate group is in a state of reacting with a compound capable of reversibly reacting with the isocyanate group and the reactivity of the isocyanate group is inactivated. Examples of the blocking agent for blocking the isocyanate group include phenols, ε-caprolactams, β-diketones, and oximes, but the reason is that the quality stability of the treatment liquid and the degree of dissociation are excellent. Therefore, β-diketones, oximes and ε-caprolactams are preferable.

Although a hydrophilic group is introduced into the polyisocyanate compound, it can be appropriately introduced within a range in which the deterioration of durability of the conductive member is suppressed and the curing is not impaired. In particular,
It is good to introduce at a ratio of 1 to 50 wt%, preferably 3 to 30 wt%. This makes it possible to obtain sufficient compatibility with water and an effect of suppressing deterioration of durability of the conductive member. Examples of the hydrophilic group include polyethers, carboxylates, sulfonates, and the like, and ammonium salts of carboxylic acids are particularly preferable because of excellent stability of the treatment liquid.

The medium containing water as a main component is a solvent containing water as a main component, and the weight of water in the total weight of the solvent is 50% by weight or more, preferably 60% by weight or more, and further 80% by weight. The above is good. As a solvent other than water, esters, ketones, alcohols, glycols, glycol esters and the like may be mixed.

As the above-mentioned polyisocyanate compound,
2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, m-phenylene diisocyanate, xylylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 1,4-cyclohexylene diisocyanate , 4,4'-dicyclohexylmethane diisocyanate, 3,3'-dimethyl-
4,4'-monophenylene diisocyanate, 3,3'-
Dimethoxy-4,4'-biphenylene diisocyanate, 3,3'-dichloro-4,4'-biphenylene diisocyanate, 1,5-naphthalene diisocyanate,
1,5-tetrahydronaphthalene diisocyanate, isophorone diisocyanate, and modified products such as isocyanurate bodies, burette bodies, adduct bodies, and allophanate bodies, and the like, and hexamethylene diisocyanate due to excellent surface treatment durability. The isocyanurate body of is preferably used.

The surface treatment liquid for a conductive member of the present invention can be applied to various conductive members such as a conductive roller and a conductive belt. Further, it can be applied to conductive members made of various materials.

The present invention also provides a surface treatment method for a conductive member, which comprises applying the above-mentioned surface treatment liquid for a conductive member to the surface of the conductive member and then performing a heat curing treatment. ing. As described above, since the polyisocyanate compound is subjected to the surface treatment by heat treatment after applying the surface treatment liquid dispersed or / and dissolved in a medium mainly composed of water, the working environment is remarkably improved, In addition to being excellent in environmental protection, it is possible to easily improve durability deterioration of the conductive member.

In the method for surface-treating a conductive member of the present invention, the temperature of the heat-curing treatment, when a blocking agent is used, depends on the kind thereof, but is 130 ° C. or higher and 200 ° C.
Hereafter, it is preferably 140 ° C. or higher and 170 ° C. or lower. If the temperature is lower than 130 ° C, the above range is
This is because the blocking agent becomes difficult to dissociate or harden. On the other hand, when the temperature is higher than 200 ° C., the conductive member deteriorates.

Although the time of the heat curing treatment depends on the temperature of the heat curing treatment, a time period in which the curing is sufficiently performed and the elastic layer is not deteriorated can be appropriately selected and is 5 minutes or more and 120 minutes or less, preferably 10 minutes. It is preferable that the time is not shorter than 60 minutes and not longer than 60 minutes.

As the method for applying the surface treatment liquid to the surface of the conductive member, conventionally known methods such as dipping, roll coating, knife coating, spray coating and the like can be used.

The present invention further relates to a conductive roller having an elastic layer mainly composed of a rubber component and having conductivity, and an outer layer covering the surface of the elastic layer, wherein the outer layer is
Provided is a conductive roller, which is obtained by heating and curing a surface treatment liquid by the above-mentioned surface treatment method for a conductive member.

As described above, in the conductive roller of the present invention,
A treatment liquid in which a polyisocyanate compound is dispersed and / or dissolved in a medium containing water as a main component is applied to the surface of the elastic layer and then heat-treated to form an extremely thin outer layer. Therefore, durability deterioration is suppressed, a clear image can be obtained even after passing the paper, the working environment is remarkably improved, and the conductive roller can be environmentally friendly.
The outer layer can also be formed by heating and curing the surface treatment liquid of the present invention by a method other than the surface treatment method of the present invention described above.

As the rubber component constituting the elastic layer of the conductive roller, polar rubbers such as epichlorohydrin rubber, nitrile rubber, chloroprene rubber, urethane rubber and acrylic rubber can be preferably used. In particular, epichlorohydrin rubber is preferable because it realizes low electric resistance and has little environmental dependence of electric resistance.

The thickness of the outer layer is 0.01 μm or more and 3 μm or more.
Hereafter, it is preferably 0.01 μm or more and 1 μm or less. The reason for setting the above range is that if the thickness is less than 0.01 μm, the durability deteriorates. On the other hand, if it is thicker than 3 μm, cracks may occur.

The elastic layer has a thickness of 2 mm or more and 10 mm.
The following is preferably 3 mm or more and 6 mm or less. The above range is set because it is difficult to obtain sufficient chargeability when the thickness is less than 2 mm. On the other hand, if it is thicker than 10 mm, insufficient charging is likely to occur and the member is too large to be made compact and lightweight.

The electric resistance value of the entire roller including the outer layer is
It is 10 ⁴ Ω · cm or more and 10 ¹⁰ Ω · cm or less, preferably 10 ⁵ Ω · cm or more and 10 ⁸ Ω · Cm or less. The above range is set because it is difficult to obtain a conductive roller smaller than 10 ⁴ Ω · cm. On the other hand, if it is larger than 10 ¹⁰ Ω · cm, there is a problem that the efficiency of transfer, charging, toner supply, etc. is lowered and it becomes unsuitable for practical use.

The hardness of the elastic layer (JIS K6253 (durometer type A)) is preferably 30 or more and 70 or less. This makes it possible to obtain appropriate flexibility as a roller.

In order to impart conductivity to the elastic layer,
Carbon black, tin oxide, titanium oxide (including those whose surface is coated with tin oxide), metal oxide such as graphite, or conductive filler such as conductive silica, metal powder such as copper, nickel and aluminum. It can also be used. However, since the belt color is black in the case of carbon black conductivity, other conductive agents (generally referred to as ionic conductive agents. Especially used for permanent antistatic agents) are used in the case of a white belt. It is preferable to use

Specific examples of the ionic conductive agent include antistatic agents and charge control agents. It is possible to adjust the electric resistance value of the elastic layer by blending these ionic conductive agents individually or in a mixture.

As the antistatic agent, any of those conventionally used in toners for developing electrostatic latent images can be used. Examples of the negatively chargeable antistatic agent include 2: 1 type metal-containing azo dyes, aromatic oxycarboxylic acids, metal complexes of aromatic dicarboxylic acids, sulfonylamine derivatives of copper phthalocyanine dyes, and sulfonamide derivative dyes of copper phthalocyanines. Can be mentioned. Examples of the positively chargeable antistatic agent include quaternary ammonium compounds, alkylpyridinium compounds, alkylpicolinium compounds, and various nigrosine dyes.

Examples of the charge control agent include organic metal complexes, metal salts, and chelate compounds such as monoazo metal complexes, acetylacetone metal complexes, hydroxycarboxylic acid metal complexes, polycarboxylic acid metal complexes, and polyol metal complexes. Other examples include quaternary ammonium salts, carboxylic acid metal salts, carboxylic acid anhydrides, carboxylic acid derivatives such as esters, and condensation products of aromatic compounds. Further, phenol derivatives such as bisphenols and calixarene are also used. The antistatic agent and the charge control agent may be used alone or in combination.

In addition to the above conductive filler, in order to improve the mechanical strength, calcium carbonate, silica, clay,
Fillers such as talc, barium sulfate and diatomaceous earth may be added.

Further, release of additives from the surface of the elastic layer,
Blended with fatty acids such as stearic acid and lauric acid, cottonseed oil, tall oil, asphalt substances, paraffin wax and other softeners, as long as they do not cause bleeding, blooming, or transfer to contact materials such as photoconductor contamination. good. In addition, phthalic acid compounds such as dimethyl phthalate and dibutyl phthalate, adipic acid compounds such as dioctyl adipate, sebacic acid compounds such as dibutyl sebacate, and plasticizers such as benzoic acid compounds may be added. Thereby, the hardness and flexibility of the elastic layer can be adjusted appropriately.

Further, imidazoles such as 2-mercaptobenzimidazole, phenyl-α-naphthylamine, N, N'-di-β-naphthyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine. Anti-aging agents such as amines such as, and phenols such as di-t-butyl-p-cresol and styrenated phenol may be blended.

Further, various additives such as a vulcanizing agent, a vulcanization accelerator, a foaming agent and the like can be blended if necessary. Examples of the vulcanizing agent include, for example, sulfur and organic-containing sulfur compounds,
A peroxide or the like can also be used. Further, as the vulcanization accelerator, slaked lime, magnesia (MgO), litharge (Pb
Inorganic or organic accelerators such as O) can be used.

The elastic layer of the above-mentioned conductive roller can be prepared by a conventional method. For example, the rubber component (kneaded material) containing additives as required may be mixed in an open roll with a required composition.
The mixture is put into a rubber kneading device such as a Banbury mixer or a kneader, kneaded at 100 ° C. for about 1 to 20 minutes, and then preformed into a tube shape by a single-screw extruder.
After vulcanization at 10 ° C. for 10 to 60 minutes, a core metal is inserted, the surface is polished, and then cut into a required size to form an elastic layer. Various known methods can be used. Vulcanization of the kneaded product may be performed by, for example, an electric press machine, can vulcanization, electron beam irradiation, or the like. The vulcanization conditions such as vulcanization time depend on the rubber component,
Determine the optimum vulcanization time with a rheometer for vulcanization test (eg, curast meter), although it depends on the type and mixing ratio of vulcanizing agent, etc. You should decide. Further, the vulcanization temperature may be set higher or lower than the above temperature as required.

[0035]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a conductive roller 10 according to an embodiment of the present invention, in which the conductive roller 10 has a cylindrical cored bar (shaft) in a hollow portion of a cylindrical elastic layer 11.
12 is press-fitted and attached, and an outer layer 13 is provided on the surface of the elastic layer 11.

The elastic layer 11 is formed into a cylindrical shape from a rubber composition in which carbon black or the like is mixed with rubber mainly composed of chloroprene rubber. The outer layer 13 is formed by dipping a surface treatment liquid in which a polyisocyanate compound in which a hydrophilic group is introduced and an isocyanate group is blocked, dispersed or / and dissolved in a medium mainly containing water by dipping. After being applied to the surface of, it is heated and cured at a temperature of 130 ° C. or higher and 200 ° C. or lower to be formed.

As described above, in the conductive roller 10, the treatment liquid in which the polyisocyanate compound is dispersed or / and dissolved in the medium mainly containing water is applied to the surface of the elastic layer 11, and then the heat treatment is performed. The outer layer 13 is formed. Therefore, deterioration of durability is suppressed by the polyisocyanate compound, a clear image can be obtained even after passing the paper, and since water is used as the solvent, the working environment is remarkably improved and the conductive roller 10 is environmentally friendly. can do. Therefore, it can be suitably used as a conductive roller such as a developing roller, a charging roller, a transfer roller for a color copying machine or a color printer.

Hereinafter, Examples 1 and 2 of the present invention and Comparative Example 1
Will be described in detail. The following composition (elastic layer) was put into a kneader, kneaded at 100 ° C. for about 1 to 20 minutes, and then extruded from a rubber kneading device. Then, the preform 160
Vulcanization was performed at 30 ° C. for 30 minutes to prepare an elastic layer, and a metal shaft (φ6 mm) was inserted into the elastic layer, and the layer was polished and cut.
Then, a surface treatment liquid having the composition shown in Table 1 below was applied to the surface of the elastic layer of each roller by dipping for 30 seconds, and then cured for 1 hour in an oven at 150 ° C. to 0.0
Forming a very thin outer layer with a thickness of 1 μm to 1.0 μm,
The conductive roller of each of Example 1 and Example 2 was obtained. A conductive roller whose surface was not treated was used as the conductive roller of Comparative Example 1. Shaft diameter φ6m
m, roller outer diameter φ12 mm, roller length 220 mm.

(Composition of Elastic Layer) The composition of the elastic layer is 80 parts by weight of chloroprene rubber (Neoprene WRT: Showa Denko Dupont Co., Ltd.) and EPDM rubber (Esprene 5).
05A: 20 parts by weight of Sumitomo Chemical Co., Ltd., carbon black (Denka Black, manufactured by Denki Kagaku Co., Ltd.) 1
8 parts by weight, 2 parts by weight of acid acceptor, 25 parts by weight of plasticizer, 1 part by weight of stearic acid, 5 parts by weight of zinc white, 1 part by weight of sulfur, and 3 parts by weight of accelerator.

[0040]

[Table 1]

In Table 1, Baihydur 3100 (manufactured by Sumika Bayer Urethane Co., Ltd.) is an isocyanurate of hexamethylene diisocyanate containing a hydrophilic group, and Baihidur TPLS2186 (manufactured by Sumika Bayer Urethane Co., Ltd.). ) Is an isocyanurate of hexamethylene diisocyanate containing a hydrophilic group blocked with an oxime.

Example 1 obtained by the above curing treatment,
The following durability test was performed on the conductive roller of Example 2 and the conductive roller of Comparative Example 1 which was not cured. The test results are shown in the lower column of Table 1.

(Durability Test) A conductive roller was attached to a copying machine, and changes in images after copying 25,000 sheets were visually evaluated. When there was no change, it was evaluated as ◯, and when stain was generated, it was evaluated as x.

As shown in Table 1, the conductive rollers of Examples 1 and 2 both had good durability test results. Also, since a treatment liquid using water as a solvent is used,
Compared to conventional treatment solutions that use organic solvents, organic solvents are not released into the atmosphere, so the working environment is good and it is superior from the viewpoint of global environment conservation. It could be confirmed. Furthermore, the conductive roller of Example 2 is
Since the treatment liquid in which the isocyanate group was blocked with the oxime was used, the quality control of the treatment liquid was easy. Therefore, in the conventional treatment liquid, the reactivity of the isocyanate group was high, which made it difficult to control the quality thereof, but the conductive roller of Example 2 can be more easily subjected to the curing treatment. Therefore, the conductive roller of Example 2 could be manufactured more easily. On the other hand, Comparative Example 1
The conductive roller of No. 1 had a poor durability test result because it was not cured.

[0045]

As is apparent from the above description, according to the present invention, a polyisocyanate compound having a hydrophilic group introduced therein is dispersed in a water-based medium which is harmless to humans and the environment. Alternatively / and because it is dissolved, volatilization of the organic solvent is suppressed compared to the conventional method using a large amount of organic solvent, so the durability is given to the conductive member without affecting the working environment or global environment. It is possible to obtain a surface treatment liquid for a conductive member which is excellent in quality controllability.

Further, the working environment of the surface treatment is remarkably improved by applying the surface treatment liquid in which the polyisocyanate compound is dispersed or / and dissolved in a medium mainly composed of water and then performing the surface treatment by the heat treatment. Therefore, the durability deterioration of the conductive member can be easily improved.

Further, a treatment liquid in which a polyisocyanate compound is dispersed or / and dissolved in a medium containing water as a main component is applied to the surface of the elastic layer, followed by heat treatment to form an outer layer. Therefore, durability deterioration is suppressed by the polyisocyanate compound, a clear image can be obtained even after passing the paper, and since water is used as a solvent, the working environment is remarkably improved, and an environment-friendly conductive roller is obtained. be able to. Therefore, at the present time when the technology of high image quality such as digitization and colorization is remarkable, it can withstand the required performance, and in particular, a conductive roller such as a developing roller, a charging roller, a color copying machine or a transfer roller for a color printer. Is extremely useful as

[Brief description of drawings]

FIG. 1A is a schematic perspective view of a conductive roller of the present invention,
(B) is a cross-sectional configuration diagram.

[Explanation of symbols]

10 Conductive roller 11 Elastic layer 12 Core bar (shaft) 13 outer layer

Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/02 101 G03G 15/02 101 4J034 15/08 501 15/08 501A 501D 15/16 103 15/16 103 103 // C08L 21:00 C08L 21:00 (72) Inventor Shunichi Washita 3-6-9 Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo Sumitomo Rubber Industries, Ltd. (72) Inventor Ken Uesaka Chuo-ku, Kobe-shi, Hyogo 3-6-9 Wakihamacho Sumitomo Rubber Industries Ltd. (72) Inventor Hiromichi Kishimoto 3-6-9 Wakihamacho Chuo-ku, Kobe-shi, Hyogo Sumitomo Rubber Industries Ltd. F-term (reference) 2H071 BA43 DA06 DA08 DA09 2H077 AC04 AD06 FA13 FA22 FA26 FA27 2H200 FA02 HA02 HB12 HB43 HB45 HB46 JA02 JA23 JA25 JA26 LC03 LC04 LC09 LC10 MA03 MA12 MA14 MA20 MB04 3J103 AA02 AA13 EA11 FA15 FA30 CA57 GA58 GA60 HA12 HA20 HA41 HA04 CA12 A04 AB37A04 A04 4F006 A58 HC17 HC52 HC64 HC67 HC71 HC73 HD03 HD04 HD12 HD15 RA1 Four

Claims (5)

[Claims] 1. A surface treatment liquid for a conductive member, wherein a polyisocyanate compound having a hydrophilic group introduced therein is dispersed or / and dissolved in a medium mainly containing water. 2. The surface treatment liquid for a conductive member according to claim 1, wherein an isocyanate group of the polyisocyanate compound is blocked. 3. A surface treatment of a conductive member, which comprises applying the surface treatment liquid for a conductive member according to claim 1 or 2 to a surface of the conductive member and then performing a heat curing treatment. Method. 4. The surface treatment method for a conductive member according to claim 3, wherein the temperature of the heat curing treatment is 130 ° C. or higher and 200 ° C. or lower. 5. A conductive roller comprising an elastic layer mainly composed of a rubber component and having conductivity, and an outer layer covering the surface of the elastic layer, wherein the outer layer is defined by claim 3 or 4. 2. A conductive roller obtained by heat-curing a surface treatment liquid by the method for surface treatment of a conductive member as described in 1.