JPH1138751A - Roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a roller for use in the electrophotographic system, which involves less variation of the resistance originating from moisture absorption, etc., has small surface roughness, sustains contamination even if it contacts with a photo-sensitive element, ensures good electrostatically charging characteristic of a toner when it is applied to a developing roller, and has a soft elastic layer to result in lesser toner cracking. SOLUTION: A roller is structured so that a elastic layer is furnished around a shaft, which is cover with a facial layer chiefly containing a copolymer whose main constituent materials are acrylic acid ester monomers and/or methacrylic acid ester monomers and carboxylic acid vinyl monomers, wherein the elastic layer is formed from (A) polymeride having at least one alkenyl radical in the molecule and structured so that the repeating unit to constitute the main chain consist chiefly of oxyalkylene unit or saturated hydrocarbon series unit, (B) a hardening agent having at least two hydrosilyl radicals in the molecule, and a reaction hardened substance of a hardening type composition chiefly containing (C) hydrosilylation catalyst and preferably containing (D) electroconductivity giving agent. The resultant developing roller can work in good performance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roller incorporated in an electrophotographic apparatus, such as a copying machine, a printer or a facsimile receiving apparatus.

[0002]

2. Description of the Related Art Various rollers such as a charging roller, a developing roller, and a transfer roller are used around a photoreceptor of an apparatus employing an electrophotographic system. Among these, the developing roller is
From the viewpoint of carrying and transporting the toner on the surface,
The properties of the surface layer are particularly important. In this developing roller, materials such as nylon resin and urethane resin are used for the purpose of negatively charging the toner. However, if these materials are used for the surface layer, water is absorbed and the roller resistance often fluctuates depending on the environment. . Further, these materials have a large dielectric constant and often cause problems in practical characteristics. on the other hand,
In many cases, a fluorine-based resin is selected as a material having a small water absorption. However, in this case, it is difficult to positively charge the toner, and a good image is often not obtained. Further, since the fluorine-based resin has a high volume resistivity and needs to be applied thinly, the unevenness of the applied thickness is often reflected in the variation of the roller resistance. Although the problem related to the developing roller has been described here, other rollers such as a charging roller and a transfer roller have the same problems as those of the developing roller in characteristics other than the toner charging property.

[0003]

SUMMARY OF THE INVENTION The present invention provides a roller having a surface layer which solves the above-mentioned problems as a roller used in an apparatus employing the above-described electrophotographic method. In particular, when a roller having a flexible elastic layer, which is a main part of the roller, is used as a developing roller, a) the toner can be charged satisfactorily. B) the fluctuation of the roller resistance due to moisture absorption is small. ,
(C) To provide a roller satisfying such characteristics that the surface roughness is small, and (d) the photoconductor is not contaminated when used in contact with the photoconductor. Further, (e) a roller is provided in which the elastic layer is flexible, the toner is less likely to crack when used as a developing roller, and the characteristics of the surface layer as described in (a) to (d) above can be further exhibited. .

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, as a resin composition constituting a surface layer, an acrylic acid ester monomer and / or a methacrylic acid ester monomer And a vinyl carboxylate monomer as a main raw material (hereinafter, referred to as an acryl-vinyl carboxylate copolymer) as a main component, thereby providing a roller capable of achieving the above object. As a result of finding that it can be obtained and further study, the present invention has been achieved. That is, the present invention relates to a roller used in an electrophotographic system, in which an elastic layer is provided around a shaft and an outer peripheral surface is covered with a surface layer, and at least the surface layer is formed of an acrylic-vinyl carboxy-based copolymer. A roller characterized by comprising a polymer as a main component (Claim 1), wherein the elastic layer which is a main part of the roller provided around the shaft has (A) at least one alkenyl group in a molecule. A polymer in which a main chain-constituting repeating unit mainly comprises an oxyalkylene unit or a saturated hydrocarbon unit, (B) a curing agent having at least two hydrosilyl groups in a molecule, and (C) a hydrosilylation catalyst. The roller (Claim 2) according to claim 1, wherein the roller (Claim 2) is made of a reaction-cured product of a curable composition containing (C) as a main component.
The roller according to claim 1 or 2, wherein the curable composition contains (D) a conductivity-imparting agent and is used as a developing roller.

The roller according to the present invention as described above can be used not only for a developing roller but also for a charging roller and a transfer roller by appropriately setting the resistance and the film thickness.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The roller according to the present invention has a diameter of 1 to 5.
An elastic layer having a JIS A hardness of about 5 to 40 °, preferably about 10 to 30 ° and a thickness of about 0.3 to 15 mm is provided around a metal shaft such as SUS (stainless steel) or aluminum having a thickness of about 25 mm. It is provided and the outer peripheral surface is covered with a surface layer, and another layer may be included between the surface layer and the elastic layer.

This roller has a resistance as a whole of about 10 ³ Ω to 10 ⁹ Ω, and a value measured by applying a load of 500 g to both ends of the shaft and applying a DC voltage of 100 V, and more preferably 10 ⁴ Ω to 10 ⁷ Ω. Ω is preferred.

The material constituting the elastic layer is E
P-based rubbers, polyether-based compounds and the like can be mentioned. Among these compounds, the curable composition for a roller according to claim 2 has a low hardness and a small compression set without adding a plasticizer.

When the main chain of the polymer as the component (A) in the curable composition is an oxyalkylene-based material, the material itself has a low volume resistivity and tends to impart conductivity. Further, when the main chain of the polymer of the component (A) is a saturated hydrocarbon-based polymer, the water absorption rate is small, and the change in electrical characteristics and the like with respect to environmental changes is small.

The resin composition constituting the surface layer of the roller according to the present invention will be described. In the present invention, the surface layer is composed of a resin composition containing an acrylic-vinyl carboxylate copolymer as a main component. This acryl-vinyl carboxylate copolymer means that the acrylate monomer, the methacrylate ester monomer, and the vinyl carboxylate monomer component are 50% by weight or more, preferably 8% by weight, in the resin component.
A copolymer containing 0% by weight or more, and a vinyl carboxylate monomer component in a resin component of 3% by weight or more, preferably 5% by weight or more, more preferably 10% by weight or more. It is united.

The vinyl carboxylate monomer component includes:
Vinyl acetate, vinyl propionate, vinyl valerate, vinyl isovalerate, and the like, among which vinyl acetate is preferably used because it is easily available, and when used as a developing roller, toner is used. Vinyl acetate is also preferable in terms of negatively charging. in this way,
The vinyl carboxylate monomer component is preferably vinyl acetate, but is not particularly limited as long as polymerization proceeds well.

Examples of the acrylate monomer component include, but are not limited to, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and the like. Examples of the methacrylate monomer component include methyl methacrylate, ethyl methacrylate, and butyl methacrylate, but are not particularly limited. Among these, methyl methacrylate is preferred from the viewpoint of availability.

One example of the method for forming the surface layer of the roller according to the present invention is to dilute the above resin composition with a solvent such as toluene, xylene or ethyl acetate, and then spray,
A method of applying by a method such as dip is used. Further, the resin composition constituting the surface layer may include a conductivity-imparting agent such as carbon black, and other inorganic fillers. The solid content of the coating solution is about 3 to 10% by weight, preferably about 5% by weight. However, a case where a conductivity-imparting agent or the like is added is also assumed, and there is no particular limitation. When the viscosity of the coating liquid is high, coating with a roll coater or the like can be mentioned. As a method for drying and curing the coating layer, heat (for example, 8
(0 ° C. × 30 minutes), but there is no particular limitation. The surface layer of the roller according to the present invention, the acrylic-
If the vinyl carboxylate copolymer is at least 50% by weight, preferably at least 80% by weight, other additives may be contained.

Next, the curable composition constituting the elastic layer in the roller according to claim 2 will be described. The polymer of the component (A) in the curable composition is a component that is cured by a hydrosilylation reaction with the component (B), and has at least one alkenyl group in the molecule. It becomes polymeric and hardens. (A)
The number of alkenyl groups contained in the component is required to be at least one from the viewpoint of hydrosilylation reaction with the component (B). In the case of a molecule having two alkenyl groups and a branch, it is desirable that two or more alkenyl groups are present at the molecular terminals. The main repeating unit constituting the main chain of the component (A) is an oxyalkylene unit or a saturated hydrocarbon unit.

In the case of a polymer in which the main repeating unit constituting the main chain is an oxyalkylene unit, the volume resistance can be 10 ⁸ to 10 ⁹ Ωcm only by adding a small amount of a conductivity-imparting agent.
Is preferable. Further, from the viewpoint of lowering the hardness of the cured product, an oxyalkylene-based polymer in which the repeating unit is an oxyalkylene unit, and more preferably an oxypropylene-based polymer in which the repeating unit is an oxypropylene unit.

Here, the oxyalkylene-based polymer is a polymer in which 30% or more, preferably 50% or more, of the units constituting the main chain are composed of oxyalkylene units. Examples of the unit include compounds derived from compounds having two or more active hydrogens, such as ethylene glycol, bisphenol compounds, glycerin, trimethylolpropane, and pentaerythritol, which are used as starting materials in the production of polymers. . In the case of an oxypropylene-based polymer, it may be a copolymer (including a graft copolymer) with a unit composed of ethylene oxide, butylene oxide, or the like.

The molecular weight of the oxyalkylene polymer as the component (A) is from 500 to 50,000 in terms of number average molecular weight (Mn) from the viewpoint of improving the balance between reactivity and low hardness. Is 1,000-40,0
00 is preferred. In particular, the number average molecular weight is 5,0
Those having a value of 00 or more, more preferably those having a molecular weight of 5,000 to 40,000 are preferred. When the number average molecular weight is less than 500, it becomes difficult to obtain sufficient mechanical properties (rubber hardness, elongation) and the like when the curable composition is cured. On the other hand, if the number average molecular weight is too large, the molecular weight per alkenyl group contained in the molecule will be large, or the reactivity will decrease due to steric hindrance, so curing is often insufficient, Further, the viscosity tends to be too high and the processability tends to be poor.

The alkenyl group contained in the oxyalkylene polymer is not particularly limited.

Embedded image (In the formula, R ¹ is a hydrogen atom or a methyl group), an alkenyl group represented by the formula ( ¹ ) is particularly preferred in terms of excellent curability.

One of the characteristics of the curable composition is that
In order to exhibit this characteristic, the number of alkenyl groups is preferably 2 or more at the molecular terminal, and the number of alkenyl groups becomes too large compared to the molecular weight of component (A). And it becomes difficult to obtain good rubber elasticity.

In the case where the component (A) is a polymer in which the main repeating unit constituting the main chain is a saturated hydrocarbon unit, it has a low water absorption rate and is preferable because the environmental fluctuation of electric resistance is small. This polymer is also a component which is cured by a hydrosilylation reaction with the component (B), as in the case of the oxyalkylene polymer, and has at least one alkenyl group in the molecule. The component (A) is required to have at least one alkenyl group from the viewpoint of a hydrosilylation reaction with the component (B).
From the viewpoint of rubber elasticity, in the case of a linear molecule, two molecules are preferably present at both ends of the molecule, and in the case of a branched molecule, two or more molecules are preferably present at the molecular terminal.

Representative examples of the polymer in which the main repeating unit constituting the main chain is a saturated hydrocarbon unit include an isobutylene polymer, a hydrogenated isoprene polymer, and a hydrogenated butadiene polymer. Can be These polymers may contain a repeating unit of another component such as a copolymer, but contain at least 50% or more, preferably 70% or more, more preferably 90% or more of a saturated hydrocarbon unit. This is important so as not to impair the low water absorption characteristic of the saturated hydrocarbon system.

The molecular weight of the polymer of the component (A) in which the main repeating unit constituting the main chain is a saturated hydrocarbon unit may be a number average molecular weight (M
n) about 500 to 50,000, and even 1,000
~ 15,000, and a liquid material having fluidity at room temperature is preferable from the viewpoint of processability.

The alkenyl group introduced into the saturated hydrocarbon polymer is the same as in the case of the oxyalkylene polymer.

Therefore, preferred specific examples of the polymer having at least one alkenyl group in the molecule and having a main repeating unit constituting a main chain of a saturated hydrocarbon as the component (A) include: A linear number average molecular weight (Mn) having two alkenyl groups at both terminals is from 2,000 to 1
Examples thereof include a polyisobutylene-based, hydrogenated polybutadiene-based, and hydrogenated polyisoprene-based polymer having a molecular weight of 5,000 and an Mw / Mn of 1.1 to 1.2.

The component (B) in the curable composition is not particularly limited as long as it is a compound having at least two hydrosilyl groups in the molecule, but the number of hydrosilyl groups contained in the molecule is too large. After curing, a large amount of hydrosilyl groups easily remain in the cured product and cause voids and cracks. Therefore, the number of hydrosilyl groups contained in the molecule is preferably 50 or less. Further, the number is preferably 2 to 30, more preferably 2 to 20, from the viewpoint of control of rubber elasticity and storage stability of the cured product. Further, in order to easily prevent foaming during curing, 20 In the following, from the viewpoint that curing failure does not easily occur even when the hydrosilyl group is deactivated, three are preferable, and the most preferable range is 3 to 20.

In the present invention, the above-mentioned hydrosilyl group is
The term “having one” means having one H bonded to Si. In the case of SiH ₂ , it has two hydrosilyl groups, but the H bonded to Si is harder to bond to different Si. And also preferable from the viewpoint of rubber elasticity.

The molecular weight of the component (B) is 30,000 as a number average molecular weight (Mn) from the viewpoint of dispersibility and roller workability when a conductivity imparting agent (component (D)) described later is added.
It is preferably 0 or less, more preferably 20,000 or less, and particularly preferably 15,000 or less. Considering the reactivity and compatibility with the component (A), 300 to 10,000
Is preferred.

Regarding the component (B), since the cohesive force of the component (A) is greater than the cohesive force of the component (B), the phenyl group-containing modification is important in terms of compatibility. Styrene-modified products are preferred from the viewpoint of compatibility with the components and availability, and α-methylstyrene-modified products are preferred from the viewpoint of storage stability.

The hydrosilylation catalyst as the component (C) is not particularly limited as long as it can be used as a hydrosilylation catalyst. Platinum simple substance, solid platinum supported on simple substance such as alumina, chloroplatinic acid (including complex such as alcohol), various complexes of platinum, chloride of metal such as rhodium, ruthenium, iron, aluminum, titanium, etc. No. Among these, chloroplatinic acid, a platinum-olefin complex, and a platinum-vinylsiloxane complex are preferable from the viewpoint of catalytic activity. These catalysts may be used alone or in combination of two or more.

The proportion of the components (A) and (B) in the curable composition as described above is such that the amount of the hydrosilyl group in the component (B) is 0.2 per mole of the alkenyl group in the component (A). -5.0 mol, more preferably 0.4-2.5 mol, from the viewpoint of rubber elasticity.

The amount of the component (C) used is as follows:
(A) 10 ^-1 to 1 based on 1 mol of the alkenyl group in the component.
0 ^-8 mol, more preferably 10 ^-1 to 10 ^-6 mol, especially 10 ^-3 mol
It is preferably used in the range of from 10 to ⁶ mol. If the amount of the component (C) is less than 10 ^-8 mol, the reaction does not proceed.
On the other hand, hydrosilylation catalysts are generally expensive and have a corrosive, and since the cured product hydrogen gas generate a large amount has a property that results in foaming greater than 10 ^-1 mol It is preferable not to use them.

Further, the curable composition as described above has
If a conductive composition is obtained by adding a conductivity-imparting agent as the component (D), it is suitable as a developing roller. Examples of the conductivity-imparting agent of the component (D) include carbon black, metal fine powder, and organic compounds having a quaternary ammonium base, a carboxylic acid group, a sulfonic acid group, a sulfate group, a phosphate group, and the like. Or a polymer, an ether ester amide, or an ether imide polymer, an ethylene oxide-epihalohydrin copolymer, a compound having a conductive unit represented by methoxypolyethylene glycol acrylate, or an antistatic agent such as a polymer compound, Examples of the compound include a compound that can impart conductivity. These conductivity imparting agents may be used alone or in combination of two or more.

It is preferable that the added amount of the conductivity-imparting agent as the component (D) be 30% by weight or less based on the total amount of the components (A) to (C), from the viewpoint of not increasing the rubber hardness.
On the other hand, from the viewpoint of obtaining a uniform resistance, the content is preferably 10% by weight or more. The required rubber hardness and the volume resistance of the cured product are 10 ³ to 10%.
The amount of addition may be determined from the balance of the physical properties so as to be 10 ¹⁰ Ωcm.

Further, in addition to the components (A) to (D), a storage stability improver such as the above-mentioned curable composition, for example,
A compound having an aliphatic unsaturated bond, an organic phosphorus compound, an organic sulfur compound, a nitrogen-containing compound, a tin compound, an organic peroxide, or the like may be added. Specific examples thereof include, but are not limited to, for example, benzothiazole, thiazole, dimethylmalate, dimethylacetylenecarboxylate, 2-pentenenitrile, 2,3-dichloropropene, and quinoline. . Among these, thiazole and dimethyl malate are particularly preferred from the viewpoint of achieving both pot life and rapid curing properties. The storage stability improvers may be used alone or in combination of two or more.

The curable composition may contain a filler, a storage stabilizer, a plasticizer, an ultraviolet absorber, a lubricant, a pigment and the like for improving processability and cost.

The roller according to the present invention comprises a curable composition as described above, urethane rubber, chloroprene rubber,
An elastic material such as EP rubber is cast, injected, extruded, etc. into a mold having a conductive shaft made of a metal shaft made of SUS or the like at the center, and is heated and cured at an appropriate temperature and time. This forms an elastic layer around the support. In this case, post-curing may be performed after semi-curing.
The roller of the present invention is obtained by applying the resin constituting the surface layer to a predetermined thickness from the elastic layer by spray coating, dip coating or the like, and drying and curing at a predetermined temperature.

[0037]

EXAMPLES Examples of the present invention will be described below together with comparative examples, but the present invention is not limited to these examples.

(Examples 1 to 4 and Comparative Examples 1 and 2) The following three types of conductive elastic layers and four types of surface layers were combined to form a layer having a thickness of about 10 mm in diameter around a SUS shaft. A conductive elastic layer having a thickness of 7.5 mm was provided, and the outer peripheral surface thereof was covered with a surface layer, thereby producing rollers of Examples 1 to 4 and Comparative Examples 1 and 2 shown in Table 1.

(Conductive Elastic Layer 1) (A-1) Allyl-terminated polyoxypropylene polymer having a number average molecular weight (Mn) of 8,000 and a molecular weight distribution of 2: 1
(B-1) polysiloxane-based curing agent (SiH value: 0.36)
(Mol / 100 g): 6.6 parts by weight, (C-1) a 10% isopropyl alcohol solution of chloroplatinic acid: 0.06 parts by weight, (D) carbon black 3030B (manufactured by Mitsubishi Chemical Corporation): 7 parts by weight, Were degassed under reduced pressure (10 mmHg or less, 120 minutes). The obtained composition was coated around the shaft, and allowed to stand for 30 minutes in a mold at an environment of 120 ° C. to be cured, thereby producing a rubber elastic layer having a thickness of 7.5 mm. JIS K6
The JIS A hardness of only the elastic layer measured according to the method described in Method 301A was 15 °.

(Conductive Elastic Layer 2) (A-2) Polyisobutylene polymer having a number average molecular weight (Mn) of 10,000 and having two vinyl groups at a terminal: 100
Parts by weight, Formula (B-2):

Embedded image A curing agent (SiH value 0.97 mol / 100 g,
1 g of dimethyl malate is added as a storage stabilizer in 100 g of the curing agent): 2.5 parts by weight, (C-2) 10% solution of chloroplatinic acid (H ₂ PtCl ₆ ) in isopropyl alcohol: 0. 06 parts by weight, (D-2) Ketjen Black EC: 3 parts by weight, (Others) Plasticizer PS-32 (manufactured by Idemitsu Kosan Co., Ltd.):
75 parts by weight, using the composition consisting of:
A rubber elastic layer having a thickness of 7.5 mm was formed around the shaft. The JIS A hardness of only the elastic layer was 15 °.

(Electroconductive Elastic Layer 3) 100 parts by weight of C-4190 manufactured by Nippon Polyurethane Co., Ltd. (polyether having an NCO content of 4.5%, viscosity of 700 cps / 75 ° C.), 4,4 ′ methylene- Bis-2-chloroaniline is 1
A composition consisting of 2.9 parts by weight of Ketjen Black EC 0.8 part by weight was coated around the shaft,
C. for 5 hours to produce a rubber elastic layer having a thickness of 7.5 mm. The JIS A hardness of only the elastic layer was 78 °.

(Surface Layer 1) An acrylic-vinyl acetate copolymer (trade name: Kanevilac L-DBF, manufactured by Kaneka Chemical Co., Ltd.) was diluted with ethyl acetate, and the solid content was reduced to 5% by weight.
A solution was prepared and applied to the outer peripheral surface of the conductive elastic body by dip, and then dried (cured) at 80 ° C. for 30 minutes.

(Surface layer 2) An acrylic-vinyl acetate copolymer (trade name: Kanevilac L-MA, manufactured by Kaneka Chemical Co., Ltd.) and the aforementioned Kanevilac L-DBF were used at a weight ratio of 1: 1. A solution was prepared by diluting with ethyl acetate so that the total solid content was 5% by weight. The solution was dipped on the outer peripheral surface of the conductive elastic layer and then dried (partially cured) at 80 ° C. for 30 minutes.

(Surface layer 3) A solution was prepared by diluting an N-methoxylmethylated nylon solution (trade name: EM-20, manufactured by Lead City Co., Ltd.) with methanol so as to have a solid content of 10% by weight. After dip coating on the outer peripheral surface of the elastic elastic layer, it was dried (cured) at 80 ° C. for 30 minutes.

(Surface layer 4) Fluorine resin solution (trade name:
A solution prepared by diluting Cefralsoft G180Y (manufactured by Central Glass Co., Ltd.) with DMF so that the solid content becomes 5% by weight is prepared, dip-coated on the outer peripheral surface of the conductive elastic layer, and then dried at 80 ° C. for 30 minutes (one time). Part cured).

(Evaluation) A roller was attached to a developing roller portion of a commercially available six-sheet machine, and was heated at 20 ° C., 60% RH, and 30 ° C.
Evaluation of image output on 2,000 sheets was performed with solid black in an 85% RH environment, and the Macbeth density on the 2,000th sheet was measured. Table 1 shows the results. The evaluation criteria are as follows. ：: Uniform and Macbeth density is 1.35 or more. ：: Uniform and Macbeth density is 1.30 or more and less than 1.35. Δ: Uniform but Macbeth concentration is less than 1.30. C: Macbeth density is partially 1.30 or more, but there are white spots. X: There is no portion where the Macbeth density is 1.30 or more, and there are white spots.

[0047]

[Table 1]

As is clear from Table 1, the roller of the present invention employs a surface layer made of an acrylic-carboxylic acid ester-based copolymer. Sufficient image density can be obtained even below.

[0049]

As described above, when the roller according to the first aspect of the present invention is used as a developing roller, the toner can be charged satisfactorily, and the fluctuation of the roller resistance due to moisture absorption or the like can be prevented. It is small, has a small surface roughness, and does not contaminate the photoconductor when used in contact with the photoconductor. Further, in the roller according to the second aspect, the elastic layer is flexible, and when used as a developing roller, there are few toner cracks and the like, so that the characteristics of the surface layer can be further exhibited. In the present specification, the roller according to the present invention is mainly described with respect to the developing roller.However, the roller according to the present invention is not limited to the developing roller, and may be applied to various rollers such as a charging roller and a transfer roller. Be adaptable.

Claims (3)

[Claims] 1. A roller for use in an electrophotographic system, wherein an elastic layer is provided around a shaft and an outer peripheral surface is covered with a surface layer, and at least the surface layer is made of an acrylate monomer and / or A roller mainly comprising a copolymer mainly composed of a methacrylate monomer and a vinyl carboxylate monomer. 2. An elastic layer, which is a main part of a roller provided around a shaft, has (A) at least one alkenyl group in a molecule, and a repeating unit constituting a main chain is mainly an oxyalkylene unit. Or a reaction cured product of a curable composition comprising, as a main component, a polymer comprising a saturated hydrocarbon unit, (B) a curing agent having at least two hydrosilyl groups in a molecule, and (C) a hydrosilylation catalyst. The roller according to claim 1, wherein the roller comprises: 3. The roller according to claim 2, wherein the curable composition contains (D) a conductivity-imparting agent and is used as a developing roller.