JPH11125239A - Electroconductive roll with low hardness - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electroconductive roll with low hardness which excels in the toner electrostatic charging characteristic, assures good toner mold-release performance, and can generate an excellent durable copying image quality. SOLUTION: The outermost layer 4 of an electroconductive roll having a low hardness is formed from a resin composition containing (A) and (B), in the condition that the content of (B) ranges in 5-40 wt.% of the total weight of (A) and (B), wherein (A) is silicone-grafted acrylic polymer consisting of repetitive units expressed by formula -(Y)k --(Z)n -, in which Y is a straight chain structural part derived from acryl series monomers, Z is a structural part derived from acryl series monomers having a structural part derived from siloxane, (k) is a positive number between 1-3000 and (n) is a positive number between 1-3000, while (B) is acryl-grafted silicone polymer whose side chain consisting of a structural part derived from acryl series monomers is turned in graft on a straight-chained main chain derived from siloxane and in which the glass transition temperature. of the structural part derived from acryl series monomers is set to the range of 30-150 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-hardness conductive roll used in an electrophotographic apparatus such as a copying machine and a printer.

[0002]

2. Description of the Related Art Conventionally, urethane resin has been used as a material for forming a conductive roll used in an electrophotographic apparatus such as a copying machine or a printer. In many cases, a low torque motor is used, and if the hardness of the urethane resin is too high,
At the start, there are problems such as the roll not rotating smoothly and a click sound due to stick-slip. Therefore, conductive rolls using a low-hardness urethane resin have been proposed (JP-A-5-323777, JP-A-3-187732).

However, since the low-hardness urethane resin used for the conductive roll has a relatively large coefficient of friction, the toner easily and physically adheres to the surface of the conductive roll. For this reason, there is a problem that toner filming is likely to occur, sufficient chargeability cannot be obtained, and image quality deteriorates with an increase in the number of images output. Therefore, as a method of reducing the friction coefficient of the urethane resin, a method of increasing the hardness of the urethane resin or increasing the crystallinity of the urethane resin can be considered. However, when the hardness of the urethane resin is increased, the requirement for lowering the hardness is not satisfied, and as described above, smooth rotation of the roll at the start is hindered. On the other hand, when the crystallinity of the urethane resin is increased, the solubility of the urethane resin in the solvent is reduced, so that the type of the solvent is limited to those having high volatility, or a problem such as inability to apply the urethane resin occurs. Workability at the time of producing a conductive roll becomes worse.

[0004] In order to solve the above-mentioned problems by reducing the friction coefficient of the urethane resin without increasing the hardness or crystallinity of the urethane resin, the present applicant contains a thermoplastic polyurethane resin and a silicone-grafted acrylic polymer. A conductive roll using a resin composition as an outermost layer forming material has already been proposed (Japanese Patent Application No. 8-121614).
issue).

[0005]

However, the conductive roll described in Japanese Patent Application No. 8-121614 has poor compatibility between the silicone-grafted acrylic polymer in the outermost layer forming material and the thermoplastic polyurethane resin, and has poor dispersibility. Because of its inferior quality, it has a problem that excellent durability copy image quality cannot be obtained, and further improvement is desired.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a low-hardness conductive roll which is excellent in toner chargeability, can obtain good toner releasability, and can obtain excellent durability copy image quality. Aim.

[0007]

In order to achieve the above object, a low-hardness conductive roll of the present invention is a low-hardness conductive roll having at least one layer formed on an outer peripheral surface of a shaft body. The outermost layer of the above layers is formed of a resin composition containing the following components (A) and (B), and the content of the component (B) is at least one of the components (A) and (B). Is set in the range of 5 to 40% by weight of the total weight. (A) A silicone graft acrylic polymer composed of a repeating unit represented by the following general formula (1), wherein the acrylic polymer portion excluding a structural portion derived from siloxane has a glass transition temperature of -35 to 30. Silicone graft acrylic polymer set in the range of ° C.

[0008]

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(B) An acrylic graft silicone polymer in which a side chain comprising a structural portion derived from an acrylic monomer is grafted to a main chain comprising a linear structural portion derived from siloxane. The glass transition temperature of the structural part derived from the acrylic monomer is 3
An acrylic graft silicone polymer set in the range of 0 to 150 ° C.

[0010] In the low hardness conductive roll of the present invention, the "outermost layer of the above-mentioned layers" refers to the layer when there is one layer, and literally means the outermost layer when there are two or more layers. Refers to the outer layer. The “silicone-grafted acrylic polymer” of the component (A) refers to a side chain composed of a silicone component by copolymerizing the (Z) _n portion and the (Y) _k portion in the general formula (1). Is grafted to the main chain composed of an acrylic polymer.

That is, the present inventors have intensively studied to find a low-hardness conductive roll which is excellent in toner chargeability, can obtain good toner releasability, and can obtain excellent durability copy image quality. In the course of that research, we focused on the resin composition that forms the outermost layer of the conductive roll, and when a resin composition containing a urethane resin as the main component was used as in the past, sufficient toner charging properties and toner separation were observed. I found out that I couldn't get the mold. As a result of further research, they recalled that instead of the conventional resin composition containing a urethane resin as a main component, a resin composition containing a silicone-grafted acrylic polymer and an acrylic-grafted silicone polymer was used. We conducted intensive studies on structure and characteristics. As a result, a silicone graft acrylic polymer (component A) and an acrylic graft silicone polymer (component B) having a specific structure and a specific glass transition temperature were found. A special resin containing the above-mentioned special silicone graft acrylic polymer (component A) and the special acrylic graft silicone polymer (component B), wherein the content of the above-mentioned acrylic graft silicone polymer (component B) is set to a specific range. The present inventors have found that the intended purpose can be achieved by using the composition, and arrived at the present invention. In addition, the special resin composition is a mixture in which the silicone-grafted acrylic polymer (component A) and the acrylic-grafted silicone polymer (component B) are compatibilized, so that the dispersibility is good, the stability of the liquid and the coating property are improved. It has been found that the film has excellent smoothness.

The acrylic graft silicone polymer (component B) has a number average molecular weight of 3,000 to 30.
It has been found that, when it is set in the range of 000, an electrically conductive roll having excellent flexibility and a low coefficient of friction can be obtained. In addition, the number average molecular weight in the present invention is a number average molecular weight in terms of polystyrene measured by a gel permeation chromatography (GPC) method.

Further, when a resin composition containing a conductive agent in addition to the above-mentioned special silicone-grafted acrylic polymer (component A) and acrylic-grafted silicone polymer (component B) is used, more excellent conductivity can be obtained. That you can get.

[0014]

Next, embodiments of the present invention will be described in detail.

In the low-hardness conductive roll of the present invention, for example, as shown in FIG. 1, an innermost layer 2 is formed along an outer peripheral surface of a shaft body 1, and an intermediate layer 3 is formed on the outer peripheral surface. One having a structure in which the outermost layer 4 is formed on the outer peripheral surface can be given.

The shaft 1 is not particularly limited.
Any conventionally known one may be used. For example, a metal core made of a solid metal body, a metal cylindrical body whose inside is hollowed out, and the like are used. Examples of the material include aluminum, stainless steel, and iron plated.

The innermost layer 2 formed on the outer peripheral surface of the shaft 1
The material for forming is not particularly limited, and any conventionally known material may be used. For example, ethylene-propylene-diene rubber (EPDM), styrene-
Butadiene rubber (SBR), silicone rubber, polyurethane elastomer, and the like. A conductive agent may be appropriately added to the above materials. Examples of the conductive agent include carbon black, graphite, potassium titanate, iron oxide, c-TiO ₂ , c
—ZnO, c-SnO ₂ , ionic conductive agents (quaternary ammonium salts, borates, surfactants, and the like). Note that the above “c−” indicates that it has conductivity. Among them, conductive silicone rubber is preferred because of its low hardness and little set.

Examples of a material for forming the intermediate layer 3 formed on the outer peripheral surface of the innermost layer 2 include acrylonitrile-butadiene rubber (nitrile rubber) (hereinafter abbreviated as “NBR”), hydrogenated acrylonitrile-butadiene rubber (hydrogenated). Nitrile rubber) (hereinafter abbreviated as “H-NBR”), polyurethane-based elastomer, chloroprene rubber (C
R), natural rubber, butadiene rubber (BR), butyl rubber (IIR) and the like, and H-NBR is preferred from the viewpoint of adhesiveness and stability of the coating solution. The above-mentioned conductive agent may be appropriately added to the above-mentioned material.

The outermost layer 4 formed on the outer peripheral surface of the intermediate layer 3 is formed of a special resin composition. This special resin composition is obtained using a special silicone graft acrylic polymer (component A) and a special acrylic graft silicone polymer (component B).

The silicone-grafted acrylic polymer (component A) used as a material for the special resin composition has a structure represented by the following general formula (1).

[0021]

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In the above general formula (1), the number of repetitions k
Is a positive number of 1 to 3000, preferably a positive number of 1 to 300. The number of repetitions n is a positive number from 1 to 3000, and preferably a positive number from 1 to 300.

In the above formula (1), Y is a linear structural part derived from an acrylic monomer. As the acrylic monomer, specifically, acrylic acid,
Methyl acrylate, ethyl acrylate, octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, propyl acrylate, n-butyl acrylate (n
BA), isobutyl acrylate (iBA), sec-butyl acrylate, tert-butyl acrylate, 2,2-dimethylpropyl acrylate, cyclohexyl acrylate, 2-tert-butylphenyl acrylate, 2-naphthyl acrylate Phenyl acrylate, 4-methoxyphenyl acrylate, 2-methoxycarbonylphenyl acrylate, 2-ethoxycarbonylphenyl acrylate, 2-chlorophenyl acrylate, acrylic acid 4
-Chlorophenyl, benzyl acrylate, acrylic acid 2
-Cyanobenzyl, 4-cyanophenyl acrylate, p-tolyl acrylate, isononyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 2-cyanoethyl acrylate, acrylic acid 3-oxabutyl, methacrylic acid, methyl methacrylate (MMA), ethyl methacrylate (EMA), octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, propyl methacrylate, n-butyl methacrylate (nBM
A), isobutyl methacrylate (iBMA), sec-butyl methacrylate, tert-butyl methacrylate,
2,2-dimethylpropyl methacrylate, cyclohexyl methacrylate, 2-tert-butylphenyl methacrylate, 2-naphthyl methacrylate, phenyl methacrylate, 4-methoxyphenyl methacrylate, 2-methoxycarbonyl methacrylate, methacrylic acid 2
-Ethoxycarbonylphenyl, 2-chlorophenyl methacrylate, 4-chlorophenyl methacrylate, benzyl methacrylate, 2-cyanobenzyl methacrylate, 4-cyanophenyl methacrylate, p-tolyl methacrylate, isononyl methacrylate, 2-hydroxy methacrylate Ethyl, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 2-cyanoethyl methacrylate, 3-oxabutyl methacrylate, γ-methacryloyloxypropyltrimethoxysilane, acrylamide (AA), butylacrylamide, N, N-dimethyl Acrylamide, piperidylacrylamide, methacrylamide, 4-carboxyphenylmethacrylamide, 4-methoxycarboxyphenylmethacrylamide, methylchloro Acrylate, ethyl-α-chloroacrylate, propyl-α-chloroacrylate, isopropyl-α-chloroacrylate, methyl-α-fluoroacrylate, butyl-α-butoxycarbonyl methacrylate, butyl-α-cyanoacrylate, methyl-α-phenyl Acrylate, isobonyl acrylate, isobonyl methacrylate, diethylaminoethyl methacrylate and the like can be mentioned. Then, one kind of these acrylic monomers is polymerized or two or more kinds are copolymerized to form a linear structural portion represented by Y.

In the above general formula (1), Z is a structural part derived from an acrylic monomer and has a structural part derived from siloxane. this is,
It is derived from those represented by the following general formula (7) or (8).

[0025]

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[0026]

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A preferred specific example of the above general formula (7) or (8) is the following structural formula (a)
To (r).

[0028]

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[0029]

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[0030]

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[0031]

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The silicone-grafted acrylic polymer (component A) having the structure represented by the general formula (1) is a glass of an acrylic polymer portion [main chain] excluding a structural portion [side chain] derived from siloxane. The transition temperature is -35
-30 ° C., preferably −
It is in the range of 30 to 0 ° C. That is, when the glass transition temperature of the acrylic polymer portion [main chain] is lower than -35 ° C, toner filming occurs because the tackiness is increased and the friction coefficient is also increased, and the copied image is deteriorated. This is because the roll becomes too hard, causing problems such as the roll not rotating smoothly at the start and a click sound.

The glass transition temperature of the acrylic polymer portion [main chain] excluding the structural portion [side chain] derived from the siloxane can be set as follows, for example. That is, the acrylic polymer portion (main chain)
Is carried out by setting the weight ratio of each acrylic monomer according to the following Fox equation so that the glass transition temperature of the above-mentioned is in the range of −35 to 30 ° C.

[0034]

[Number 1] _{1 / Tg = (W 1 /} Tg 1) + (W 2 / Tg 2) +
In _{... + (W m / Tg m} ) W 1 + W 2 + ... + W m = 1 [the above formula, Tg refers to the glass transition temperature of the acrylic polymer _{portion, Tg 1, Tg 2, ...} , Tg m each acrylic The glass transition temperature of the monomer. W ₁ ,
W ₂ ,..., W _m are weight ratios of the respective acrylic monomers. ]

The above glass transition temperature (Tg) is determined by DSC
(Differential scanning calorimetry) or a dynamic viscoelasticity tan δ peak.

The number average molecular weight of the silicone graft acrylic polymer (component A) having the structure represented by the general formula (1) is preferably set in the range of 10,000 to 300,000, particularly preferably. 30,000-1
It is in the range of 00,000. That is, if the number average molecular weight of the silicone graft acrylic polymer (component A) is less than 10,000, the strength of the outermost layer tends to be inferior, and if it exceeds 300,000, formation of the outermost layer becomes difficult. .

The number average molecular weight of the (Z) _n portion in the silicone graft acrylic polymer (component A) having the structure represented by the general formula (1) is 260 to 40,000.
It is preferable to set the value in the range of
The range is from 00 to 25,000. That is, when the number average molecular weight of the (Z) _n portion is less than 260, the effects of silicone such as flexibility, low friction coefficient, and releasability are reduced, and when it exceeds 40,000, stickiness occurs. is there.

The content of the (Z) _n portion is 5 to 5% of the total weight of the silicone-grafted acrylic polymer (A component).
It is preferable to set so as to be in the range of 60% by weight. That is, when the content of the (Z) _n portion is less than 5% by weight, it is difficult to obtain the effects of silicone such as flexibility, low friction coefficient, and releasability, and when it exceeds 60% by weight, the silicone is sticky. This is because it occurs.

The special silicone-grafted acrylic polymer (component A) can be produced, for example, as follows. That is, the above (Y) _k part and (Z) _n
The portion can be produced by radical copolymerization in the presence of an azo-based polymerization initiator. Such polymerization is preferably performed by a solution polymerization method using a solvent, a bulk polymerization method, an emulsion polymerization method, or the like, and particularly preferably a solution polymerization method.

Examples of the azo polymerization initiator include azobisisobutyronitrile (AIBN), azobis-4-cyanovaleric acid, azobis (2,4-dimethylvaleronitrile), and azobis (4-methoxy-2,4- Dimethylvaleronitrile), dimethyl-2,2'-azobisisobutyrate, azobis-1-cyclohexacarbonitrile and the like, with AIBN being particularly preferred.

The polymerization temperature during the radical copolymerization is 50.
To 150 ° C, particularly preferably 60 to 100 ° C
It is. Further, the polymerization time is preferably 3 to 100 hours,
Particularly preferably, it is 5 to 10 hours.

The special silicone-grafted acrylic polymer (component A) in the present invention has a structure represented by the general formula (1), and this structure further includes another acrylic monomer. And a structure represented by the following general formula (6), in which a linear structural portion [(X) _m portion] derived from is connected.

[0043]

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In the above general formula (6), X is a linear structural part derived from an acrylic monomer, and the acrylic monomer includes those exemplified in the above general formula (1). And similar ones. However, Y and X must be different from each other. The number of repetitions m is a positive number from 1 to 10,000, and preferably a positive number from 100 to 3,000.

The special acrylic graft silicone polymer (component B) used together with the special silicone graft acrylic polymer (component A) has a side chain composed of a structural portion derived from an acrylic monomer and has a side chain derived from siloxane. Is grafted to a main chain consisting of a linear structural part.

The main chain in the special acrylic graft silicone polymer (component B) is composed of a linear structural portion derived from siloxane, and particularly has the following general formula (2):
What consists of a structural part represented by-(4) is preferable.

[0047]

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[0048]

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[0049]

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Preferred specific examples of the structural portion represented by the general formula (2) include those represented by the following structural formulas.

[0051]

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X in the general formulas (3) and (4) represents hydrogen or a carbon functional group such as a halogenated hydrocarbon group and a cyanated hydrocarbon group. Examples of the halogenated hydrocarbon group include a halogenated alkyl group, a halogenated aryl group, a halogenated aralkyl group, and a halogenated alkenyl group. Examples of the cyanated hydrocarbon group include a cyano group and an aralkyl cyanide group. Group, aryl cyanide group, aralkyl cyanide group, alkenyl cyanide group and the like.

The special acrylic graft silicone polymer (component B) has a glass transition temperature of a structural part (side chain) derived from an acrylic monomer of 30 to 150 ° C.
, And preferably in the range of 60 to 12
It is in the range of 0 ° C. That is, the glass transition temperature of the structural part [side chain] derived from the acrylic monomer is 30.
When the temperature is lower than 150 ° C., the effects of lowering the coefficient of friction, releasability, and stickiness are reduced. When the temperature is higher than 150 ° C., the solubility in a solvent is reduced or the compatibility in a polymer is reduced. This is because it is difficult to obtain the effect of preventing filming. The setting of the glass transition temperature of the structural portion [side chain] derived from the acrylic monomer and the measurement of the glass transition temperature are performed in the same manner as in the case of the silicone-grafted acrylic polymer (component A).

In the special acrylic graft silicone polymer (component B), the number average molecular weight of the main chain composed of a linear structural portion derived from siloxane is 1,1.
It is preferable to set in the range of 500 to 20,000,
Particularly preferably, it is in the range of 3,000 to 10,000. That is, the number average molecular weight of the main chain portion is 1,50.
If it is less than 0, it is difficult to obtain the effects of silicone such as appropriate chargeability, low friction coefficient, and releasability, and if it exceeds 20,000, the compatibility with the component A decreases, and the effect decreases. Otherwise, stickiness of the silicone occurs.

On the other hand, the side chain in the special acrylic graft silicone polymer (component B) comprises a structural portion derived from an acrylic monomer. Examples of the acrylic monomer include the same ones as described in the silicone graft acrylic polymer (A component).

As the side chains in the special acrylic graft silicone polymer (component B), those having a structural portion represented by the following general formula (5) are particularly preferable.

[0057]

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Preferable specific examples of the structural portion represented by the general formula (5) include those represented by the following structural formula.

[0059]

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In the special acrylic graft silicone polymer (component B), the number average molecular weight of the side chain comprising the structural portion derived from the acrylic monomer is 200.
It is preferably set in the range of ２０20,000, particularly preferably in the range of 1,000〜１０10,000. That is, if the number average molecular weight of the side chain portion is less than 200, it is difficult to obtain an appropriate chargeability, and the above effect cannot be obtained. If the number average molecular weight is more than 20,000, dispersibility (compatibility) in component A is poor. This is because it is difficult to obtain the above-mentioned effect by separating.

The special acrylic graft silicone polymer (component B) is formed, for example, by combining a structural portion derived from the siloxane and a structural portion derived from the acrylic monomer with the azo polymerization initiator described above. It can be produced by the above-mentioned radical copolymerization in the presence.

Alternatively, the special acrylic graft silicone polymer (component (B)) is prepared by combining a structural portion derived from the siloxane and a structural portion derived from an acrylic monomer in the presence of an anionic polymerization catalyst. It can also be produced by an anionic polymerization reaction. As the anionic polymerization catalyst, lithium, alkali metals such as sodium, aliphatic hydrocarbons such as methyl, ethyl, propyl, butyl, naphthalene, anthracene, phenanthrene, triphenylene, naphthacene, acenaphthylene, trans stilbene, biphenyl, styrene, methyl styrene And aromatic hydrocarbons such as divinylbenzene, benzonitrile, diphenylethylene and diphenylbutadiene. These may be used alone or in combination of two or more.

The special acrylic graft silicone polymer (component B) thus obtained preferably has a number average molecular weight in the range of 3,000 to 300,000, particularly preferably 10,000 to 100,000. Range. That is, when the number average molecular weight of the component B is less than 3,000, the above-mentioned effects are hardly obtained, and the bleeding may contaminate the photoreceptor.
If it exceeds 0, the compatibility of the component A will be reduced, and it will be difficult to obtain effects such as separation and low friction.

In the special acrylic graft silicone polymer (component B), a main chain consisting of a linear structural part derived from the siloxane and a side chain consisting of a structural part derived from an acrylic monomer are used. Is preferably set in the range of main chain / side chain = 5/95 to 60/40, and particularly preferably main chain / side chain = 10.
/ 90 to 40/60. That is, when the ratio of the main chain exceeds 60 (the ratio of the side chains is less than 40), the silicone component tends to increase too much and tend to be charged too much.
The ratio of the main chain is less than 5 (the ratio of the side chains exceeds 95)
This is because it is difficult to obtain appropriate chargeability and releasability due to reduced compatibility, and the effect on strength tends to be reduced.

The content of the special acrylic graft silicone polymer (component B) needs to be set so as to be in the range of 5 to 40% by weight of the total weight of the component A and the component B, preferably 10 to 30% by weight. % Range. That is, when the content of the component B is less than 5% by weight, it is difficult to obtain an appropriate charging property and an effect of preventing toner filming, and when it exceeds 40% by weight, the releasability is deteriorated or the compatibility is deteriorated. This is because the physical properties deteriorate and the physical properties deteriorate.

The special resin composition for forming the outermost layer of the conductive roll of the present invention includes, in addition to the special silicone graft acrylic polymer (component A) and the special acrylic graft silicone polymer (component B), The above-mentioned conductive agent may be appropriately added.

It should be noted that a charge control agent may be appropriately added to the above-mentioned special resin composition. As the charge control agent, conventionally used quaternary ammonium salts,
Examples thereof include borates, azine-based (nigrosine-based) compounds, azo compounds, metal complexes of oxynaphthoic acid, and surfactants (anionic, cationic, nonionic). Also,
The special resin composition includes fillers such as titanium oxide, calcium carbonate, talc, clay, and silica, stabilizers, ultraviolet absorbers, antistatic agents, reinforcing agents, lubricants, release agents, dyes,
Pigments, flame retardants, oils and the like can be added as needed. Further, the special resin composition can be crosslinked with a curing agent. Examples of the crosslinking agent include an isocyanate group-containing material and a curing agent containing an amino group, an epoxy group, a carboxyl group, a —SH group, and the like.

The special resin composition for forming the outermost layer of the low hardness conductive roll of the present invention is produced, for example, as follows. That is, first, a special silicone-grafted acrylic polymer (component A) and an acrylic-grafted silicone polymer (component B) are prepared according to the method described above, and these are dissolved in an organic solvent. Then, if necessary, a material to which a conductive agent or the like has been added is dispersed by a sand mill or the like to prepare a coating liquid for coating. Alternatively, the silicone-grafted acrylic polymer (component A), the acrylic-grafted silicone polymer (component B), the conductive agent, and the like are dispersed in a biaxial kneader or the like and dissolved in the organic solvent to form a coating for coating. A liquid may be prepared. In this way, the intended special resin composition (coating liquid) can be prepared. Examples of the organic solvent include methyl ethyl ketone, toluene, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, methyl isobutyl ketone, cyclohexane, methanol, isopropyl alcohol and the like. These may be used alone or in combination of two or more.

The low hardness conductive roll of the present invention
For example, it is produced as follows. That is, first,
The components for the innermost layer 2 forming material are kneaded using a kneading machine such as a kneader to prepare the innermost layer 2 forming material. Also,
The components for the material for forming the intermediate layer 3 are kneaded using a kneader such as a roll, and the organic solvent is added to this mixture, followed by mixing and stirring to prepare a material for forming the intermediate layer 3 (coating liquid). . Further, a special resin composition (coating liquid) as the material for forming the outermost layer 4 is prepared according to the method described above.

Next, after preparing a metal core, an adhesive, a primer and the like are applied as required, and as shown in FIG. The material for forming the innermost layer 2 is poured into the cylindrical mold 6, and the upper lid 7 is fitted over the cylindrical mold 6. Then, the entire roll mold is heated to vulcanize the innermost layer 2 forming material (150 to 22).
(0 ° C. × 1 hour) to form the innermost layer 2. Subsequently, the shaft 1 on which the innermost layer 2 is formed is released from the mold, and the reaction is completed as required (200 ° C. × 4 hours). Then, a coating liquid as a material for forming the intermediate layer 3 is applied to the outer periphery of the innermost layer 2, or the roll on which the innermost layer 2 has been formed is immersed in the coating liquid and pulled up, followed by drying and heat treatment. Thereby, the intermediate layer 3 is formed on the outer periphery of the innermost layer 2. Further, after applying a special resin composition (coating liquid) as a material for forming the outermost layer 4 on the outer periphery of the intermediate layer 3, or dipping the roll on which the intermediate layer 3 has been formed into the coating liquid and pulling it up By performing drying and heat treatment, the outermost layer 4 is formed on the outer periphery of the intermediate layer 3. The method of applying the coating liquid is not particularly limited, and includes a conventionally known dipping method, spray coating method, roll coating method, and the like. In this way, it is possible to produce a conductive roll in which the innermost layer 2 is formed along the outer peripheral surface of the shaft body 1, the intermediate layer 3 is formed on the outer periphery, and the outermost layer 4 is formed on the outer periphery. it can.

In the low hardness conductive roll of the present invention, the thickness of each layer is appropriately determined according to the use of the conductive roll. For example, when used as a developing roll, the thickness of the innermost layer is usually preferably set in the range of 0.5 to 10 mm, particularly preferably 3 to 6 mm. In addition, the thickness of the intermediate layer is preferably set in the range of usually 1 to 90 μm, and particularly preferably 3 to 15 μm. The thickness of the outermost layer is preferably set in the range of 3 to 100 μm, particularly preferably 5 to 50 μm.

The hardness of the low-hardness conductive roll of the present invention is such that the hardness measured by JIS A is 70 (Hs: J
It is preferably in the range of IS A) or less, particularly preferably in the range of 60 (Hs: JIS A) or less.

The low-hardness conductive roll of the present invention is suitable for a developing roll, but is not necessarily limited to a developing roll, and can be applied to a transfer roll, a charging roll and the like. Although the low-hardness conductive roll of the present invention has a three-layer structure in FIG. 1, the layer formed on the outer periphery of the shaft body 1 does not necessarily have to be a three-layer structure. An appropriate number of layers are formed depending on the conditions. However, the outermost layer (in the case of a single layer, that layer) must be formed of the special resin composition.

Next, examples will be described together with comparative examples.

First, prior to Examples and Comparative Examples, a core metal (diameter: 10 mm, made of SUS304) serving as a shaft was prepared, and an innermost layer forming material and an intermediate layer forming material shown in Table 1 below were prepared. . Then, according to the above-described method, after forming the innermost layer on the outer peripheral surface of the shaft body, an intermediate layer was further formed on the outer peripheral surface to produce a roll base. In addition,
The hardness, electric resistance and thickness of each layer are also shown in Table 1 below.

[0076]

[Table 1]

On the other hand, silicone graft acrylic polymers A to D composed of the following repeating units were prepared.

[0078]

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[0079]

Examples 1-6, Comparative Examples 1-6 Tables 2 and 3 below
Were mixed in the proportions shown in the same table to prepare a resin composition (coating liquid). This resin composition (coating liquid) is applied to the outer peripheral surface of the intermediate layer of the roll base by dipping, and then dried (150 ° C. × 30 ° C.).
Then, the intended conductive roll was produced (see FIG. 1). The thickness of the outermost layer of the conductive roll thus obtained was 20 μm. The glass transition temperature (acrylic polymer portion), the average molecular weight and the content of the (Z) _n portion of the silicone-grafted acrylic polymer are as follows:
The results are shown in Tables 2 and 3 below. The acryl-grafted silicone polymer was prepared according to the method described above. The acryl-grafted silicone polymer had a glass transition temperature (a structural portion derived from an acrylic monomer), an average molecular weight, a main chain, and a side chain. The chain structure, the ratio of the main chain to the side chain (weight ratio), and the ratio of the acrylic graft silicone polymer to the whole polymer (weight%) are also shown in Tables 2 and 3 below.

[0080]

[Table 2]

[0081]

[Table 3]

With respect to the conductive rolls of the example and comparative examples thus obtained, the electric resistance, the coefficient of friction, the hardness, the roll rotation torque, the toner charging property, the copy image quality and the durability copy image quality were determined according to the following criteria. Were compared and evaluated. The results are shown in Tables 4 and 5 below.

[Electrical Resistance] The electrical resistance of the outermost layer of the conductive roll was measured as shown in FIGS. 3 (A) and 3 (B). That is, the electrode 11 having the shape shown in FIG. 3A was formed at 20 places on the surface of the roll 10 shown in FIG. 3B, and measured by a measurement system shown in FIG. 3B. In the figure, 1
1a is a main electrode and 11b is a guard electrode. The electrical resistance values in the examples and comparative examples are the median of the measured values at 20 points.

[Friction Coefficient] The friction coefficient was measured using a static friction coefficient meter (manufactured by Kyowa Interface Science Co., Ltd.) as shown in FIG. That is, using a resin composition to be the outermost layer forming material of the conductive roll, a coating film 21 having a thickness of 50 to 100 μm is used.
Was set on the fixed base 22, and the measurement was performed under the conditions of a moving speed of 0.3 cm / sec and a load of 100 g. In the figure, 23 is a steel ball (3 mm in diameter), 24 is a balance for zero adjustment, 25 is a load cell, and 26 is a load (100
g).

[Hardness] JIS A using a conductive roll
Was measured for hardness.

[Roll Rotation Torque] A conductive roll was pressed into contact with the fixed photosensitive member, the conductive roll was rotated by a torque motor, and the current value at the start of the movement was measured. The pressure at which the conductive roll was pressed into contact with the photoreceptor was set to a pressure such that the contact portion of the conductive roll was recessed by 0.3 mm in the radial direction. Then, the obtained measured value is converted into a torque, and a case where the calculated value always indicates less than 3 kgf-cm is indicated as ○, which indicates a value less than 3 kgf-cm, but 3 kf at the initial stage.
The case where gf-cm or more is indicated is indicated by △, and the case where 3 kgf-cm or more is always indicated is indicated by x.

[Toner Charging Property] The toner charging property was measured as follows under the condition that the charge amount on the conductive roll was 20 ° C. × 50% RH. That is, as shown in FIG. 5, a developer (toner) is placed on the surface of the conductive roll 30.
32 are formed, and the developer 32 is
Was aspirated and measured using a Faraday cage 34 (Faraday cage method). In the figure, 35 is a filter, 36 is an insulator pipe, 37 is an electrometer, and 38 and 39 are conductors and are separated from each other.

[Copy Image Quality] A conductive roll was incorporated in an electrophotographic copying machine as a developing roll, and an image was formed under the conditions of 20 ° C. × 50% RH. A solid black image having sufficient density and no image unevenness or white spots was displayed as ○, and an image having insufficient density, image unevenness or any one of white spots was displayed as x.

[Durable copy image quality] A conductive roll was incorporated into an electrophotographic copying machine as a developing roll, and the temperature was 20 ° C. × 50% R.
An image was obtained under the condition of H. After copying 3,000 sheets and 5,000 sheets, a solid black image having sufficient density and having no image unevenness or white spots was generated in any one of O, insufficient density, image unevenness, and white spots. Those were indicated as x.

[0090]

[Table 4]

[0091]

[Table 5]

From the results shown in Tables 4 and 5, the conductive roll of the example product was larger than the conductive roll of the comparative product.
It can be seen that the coefficient of friction is low, the hardness is low, the roll rotation torque is small, the toner chargeability is excellent, and the copy image quality and the durability copy image quality are excellent. On the other hand, it can be seen that all the conductive rolls of the comparative examples are inferior in durability copy image quality after copying 5,000 sheets. In particular, it can be seen that the conductive rolls of Comparative Example 3 and Comparative Example 5 already have inferior durability copy image quality after 3,000 copies.

[0093]

As described above, the low-hardness conductive roll of the present invention contains the above-mentioned special silicone graft acrylic polymer (component A) and the special acrylic graft silicone polymer (component B). The outermost layer is formed using a special resin composition in which the content of the polymer (B component) is set in a specific range.
Therefore, the above-mentioned silicone graft acrylic polymer (component A) and acrylic graft silicone polymer (B
Component) and has a good dispersibility.
The stability of the liquid and the smoothness of the coating film are improved. As a result, the toner chargeability is excellent, the toner scattering property is small, the toner releasing property is good, toner filming is hard to occur, toner adhesion can be prevented, and stable toner chargeability for a long time Can be obtained, and the image quality can be improved.

The acrylic graft silicone polymer (component B) has a molecular weight of 3,000 to 300,
By setting the value in the range of 000, a low-hardness conductive roll having excellent flexibility and a low coefficient of friction can be obtained.

Further, by using a resin composition containing a conductive agent in addition to the silicone-grafted acrylic polymer (component A) and the acrylic-grafted silicone polymer (component B), the conductive property of the low-hardness conductive roll can be improved. The properties are further improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of a low hardness conductive roll of the present invention.

FIG. 2 is a cross-sectional view illustrating an example of a method for producing a low hardness conductive roll of the present invention.

FIG. 3A is an explanatory view showing a shape of an electrode formed on a roll surface when measuring an electric resistance of the conductive roll, and FIG. 3B is a view showing an electric resistance value of the conductive roll using the electrode. FIG. 4 is an explanatory diagram showing a measurement system of FIG.

FIG. 4 is an explanatory diagram showing a measurement state of a friction coefficient by a static friction coefficient meter.

FIG. 5 is an explanatory diagram illustrating a measurement state of a Faraday cage method for measuring a toner charge amount.

[Explanation of symbols]

 1 shaft 2 innermost layer 3 middle layer 4 outermost layer

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 51/08 C08L 51/08 83/10 83/10 G03G 15/02 101 G03G 15/02 101 15/08 501 15/08 501D 15/16 103 15/16 103 // B29K 83:00 (72) Inventor Kenichi Ohhoe Komaki City, Aichi Pref.

Claims (6)

[Claims] 1. A low-hardness conductive roll in which at least one layer is formed on the outer peripheral surface of a shaft body, wherein the outermost layer among the layers contains the following components (A) and (B). A low hardness formed by a resin composition, wherein the content of the component (B) is set in the range of 5 to 40% by weight of the total weight of the components (A) and (B). Conductive roll. (A) A silicone graft acrylic polymer composed of a repeating unit represented by the following general formula (1), wherein the acrylic polymer portion excluding a structural portion derived from siloxane has a glass transition temperature of -35 to 30. Silicone graft acrylic polymer set in the range of ° C. Embedded image (B) The acryl-grafted silicone polymer, wherein a side chain comprising a structural portion derived from an acrylic monomer is grafted to a main chain comprising a linear structural portion derived from siloxane, The glass transition temperature of the structural part derived from the system monomer is 30 to 150 ° C.
Acrylic grafted silicone polymer set in range. 2. A main chain comprising a linear structural part derived from siloxane in the component (B) is selected from structural parts represented by the following general formulas (2) to (4). The side chain consisting of at least one structural part and the structural part derived from the acrylic monomer in the component (B) is a structural part represented by the following general formula (5). Item 4. A low hardness conductive roll according to Item 1. Embedded image Embedded image Embedded image Embedded image 3. The low-hardness conductive roll according to claim 1, wherein the silicone-grafted acrylic polymer as the component (A) is composed of a repeating unit represented by the following general formula (6). . Embedded image 4. The acrylic graft silicone polymer as the component (B) has a number average molecular weight of 3,000 to 30.
The low-hardness conductive roll according to any one of claims 1 to 3, which is set in a range of 000. 5. The method according to claim 1, wherein the content of the (Z) _n part in the component (A) is set in a range of 5 to 60% by weight based on the total weight of the component (A). Item 6. The low-hardness conductive roll according to item 6. 6. The low hardness conductive material according to claim 1, wherein the resin composition further contains a conductive agent in addition to the components (A) and (B). roll.