JP2003084546A - Electrostatic charging member and electrostatic charging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic charging member which hardly firmly sticks to a photoreceptor, is small in friction and is free of toner adhesion and electrostatic charging device. SOLUTION: The electrostatic charging member which is a electrostatic charging member for electrostatically charging a body to be electrostatically charged by being touched to the body to be electrostatically charged and impressing a voltage between itself and the body to be electrostatically charged, in which the electrostatic charging member consists of an elastic layer and at least one layer of resin layer and this resin layer is a resin containing <=20 mass% polysiloxane-containing (meth)acryl monomer and the electrostatic charging device using the electrostatic charging member.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging member used for charging an object to be charged such as a photoconductor used in an electrostatic latent image forming process in a copying machine, a printer and the like, and a charging device using the same. It is about.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic process in a copying machine, a printer or the like, first, the surface of a photoconductor is uniformly charged, and an image is projected from an optical system on the photoconductor to expose a portion exposed to light. A method is used in which a latent image is formed by erasing the charge, then a toner image is formed by the adhesion of toner, and the toner image is transferred to a recording medium such as paper to print. In this case, the corona discharge method has been generally adopted as the operation of charging the first photoreceptor. However, this corona discharge method is 6-10k
Since a high voltage of V is required, it is not preferable from the viewpoint of safe maintenance of the machine. Further, since harmful substances such as ozone are generated during corona discharge, there is an environmental problem. For this reason, efforts have been made on a charging method that can perform charging at a lower applied voltage than that of corona discharge and can suppress the generation of harmful substances such as ozone. As a trial of such a charging method, a contact method has been proposed in which a charging member to which a voltage is applied is brought into contact with an object to be charged such as a photoconductor with a predetermined pressing force to charge the object to be charged. Examples of the charging member used in this contact charging method include (meth) acrylic, on the surface of an elastic layer such as rubber or urethane foam for ensuring surface smoothness, adjusting electric resistance, and improving charging characteristics. It is known that a resin layer is formed by applying a resin solution such as urethane, nylon, polyethylene, epoxy, polyester, polyether, polystyrene, phenol, polyamide, urethane-modified (meth) acrylic by a dipping method or a spray method. ing. In addition, (meth) acrylic refers to methacrylic and acrylic. In particular, it is already known that the urethane-modified (meth) acrylic resin has excellent charging properties and charging environment stability, and that it has no variation in charging performance in production.
No. 3,114,931 and Japanese Patent Laid-Open No. 8-212696. In addition, this resin also has the characteristics that it has a large elastic force and coating film strength because it has a urethane portion, and it also has the characteristic that it is excellent in the return property against deformation. However, with the recent cost reduction, high performance, multi-functionality, and multi-environment, in the contact charging method, the above-mentioned resin is brought into contact with the photoconductor for a long period of time, resulting in close contact with the photoconductor. However, problems such as peeling of the coating film and consequent contamination of the photoconductor have begun to occur. In addition, poor charging due to toner adhesion to the charging member, and further toner adhesion to the charging member depending on the strength of adhesion, and toner fusing or abrasion of the photosensitive member due to friction with the photosensitive member may cause image defects. Is getting close up as well. For this reason, in recent years, there has been an increasing demand for a coating film that covers the charging member to have properties such as low adhesion and adhesion to the photoconductor and low toner adhesion.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and in the formation of a latent image in a copying machine, a printer or the like, it is difficult to adhere to a photosensitive member, friction is small, and toner is not attached. It is an object of the present invention to provide a charging member that is excellent in charging characteristics and stability of a charging environment and can obtain a good image, and a charging device using the charging member.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found the following. That is, as a measure for improving the above problem, a silicone chain is contained in a urethane prepolymer of the main chain, or a silicone component is contained in a urethane-modified acrylic resin by a method such as grafting a polysiloxane-containing acryl on a side chain. There was a way.
However, according to this method, although a stable improvement in the frictional property to the photoconductor was observed, a stable effect was not obtained with respect to the toner adhesion, the adhesion to the photoconductor, and the photoconductor contamination. . As a result of further diligent studies, the present inventors have formed a charging member including an elastic layer and a resin layer, in which the outermost layer of the resin layer is formed of a resin containing a specific amount of a polysiloxane-containing (meth) acrylic monomer. Due to
It has been found that the above object can be easily achieved with a small content of siloxane. The present invention has been completed based on such findings. That is, the present invention relates to a charging member which is brought into contact with a member to be charged, and a voltage is applied between the member and the member to be charged so that the member to be charged is charged.
It is composed of an elastic layer and at least one resin layer, and the resin layer contains a polysiloxane-containing (meth) acrylic monomer.
The present invention provides a charging member characterized by being formed of a resin containing 0 mass% or less, and a charging device using this charging member.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below. Since the charging member of the present invention is of the contact charging type, it may be any member that can contact the member to be charged,
The shape is not particularly limited, but various shapes such as a roll shape, a plate shape, and a block shape can be applied, and the roll shape is usually preferable. In the case of a roll, a shaft made of metal or plastic may be arranged inside the roll. The structure of the charging member of the present invention is a structure having an elastic layer and a resin layer,
The elastic layer is formed of an elastic body. The elastic body is not particularly limited, and can be formed of rubber or resin conventionally used as an elastic layer of a charging member, or a foamed body (foam) thereof. Specifically, a rubber whose base rubber is polyurethane, silicone rubber, butadiene rubber, isoprene rubber, chloroprene rubber, styrene-butadiene rubber, ethylene-propylene rubber, polynorbornene rubber, styrene-butadiene-styrene rubber, epichlorohydrin rubber, etc. The composition is exemplified, but polyurethane is particularly preferable, and more preferably the expansion ratio is
Polyurethane foam of 1.5 to 50 times is used. In addition, the density of the foam in this case is 0.05 to 0.9 g / c.
m ³ is suitable. When the density is less than 0.05 g / cm ^3, there may be insufficient contact pressure between the member to be charged, also exceeds 0.9 g / cm ^3, the contact pressure between the member to be charged is Since it is too large, there is a risk of damaging the body to be charged.

A predetermined conductivity can be imparted to the elastic layer by adding a conductive agent such as an ionic conductive agent or an electronic conductive agent. Examples of the ion conductive agent include tetraethylammonium, tetrabutylammonium,
Perchlorates, chlorates, hydrochlorides, bromates such as dodecyltrimethylammonium such as lauryltrimethylammonium, octadecyltrimethylammonium such as stearyltrimethylammonium, hexadecyltrimethylammonium, benzyltrimethylammonium and modified aliphatic dimethylethylammonium , Ammonium salts such as iodate, borofluoride, sulfate, alkylsulfate, carboxylate and sulfonate; perchloric acid of alkali metal or alkaline earth metal such as lithium, sodium, calcium and magnesium Examples thereof include salts, chlorates, hydrochlorides, bromates, iodates, borofluorides, trifluoromethylsulfates and sulfonates.

On the other hand, as an example of the electronic conductive agent, ketsche is used.
Conductive carbon black such as carbon black and acetylene black
Rack; SAF, ISAF, HAF, FEF, GPF,
Carbon black for rubber such as SRF, FT, MT; Oxidation
Treated carbon black for ink, pyrolysis carb
Black, graphite; tin oxide, titanium oxide, acid
Conductive metal oxide such as zinc oxide; metal such as nickel and copper
Is mentioned. These conductive agents may be used alone or in combination.
You may use it in combination of 2 or more types. Also these guides
There is no particular limitation on the amount of the electrical agent added, depending on various situations.
However, in the case of ion conductive agent, rubber material
0.01 to 5 parts by mass, preferably 100 parts by mass,
It is preferably in the range of 0.05 to 2 parts by mass. Also electronic conductivity
In the case of agents, it is usually 0.5 to 50 parts by mass, preferably 1 to 4
The range is 0 parts by mass. This gives the volume resistance of the elastic layer.
Rate 10³-10^TenΩ · cm, especially 10^Four-10 ⁸Ω ・
It is preferable to adjust to cm. In addition, this conductive elastic layer
In addition to the above conductive agents, other conductive materials
Agents, fillers, crosslinkers, foaming agents and other additives for rubber
It can be added.

The charging member of the present invention has one or more resin layers. In the present invention, as the resin used for the resin layer, (meth) acrylic, urethane, nylon, polyethylene, epoxy, polyester, polyether, polystyrene, phenol, polyamide, AB
Examples of the resin include S and urethane-modified (meth) acrylic. Of these, urethane-modified (meth) acrylic resin is particularly preferable. These resins and (meth) acrylic monomers containing a high-molecular-weight polysiloxane having a molecular weight of 3000 or more are grafted, copolymerized, or bonded by using an active hydrogen group and an isocyanate group to directly bond to the resin. By using a resin in which a (meth) acrylic monomer containing a high molecular weight polysiloxane having a molecular weight of 3000 or more is used, the effects of reducing friction, preventing adhesion, and reducing toner adhesion are further improved. Here, the kind of the high-molecular-weight polysiloxane-containing (meth) acrylic monomer is not particularly limited, and examples thereof include those in which polysiloxane is bonded to one end of methyl methacrylate as shown in the following formula (1). To be

[0009]

[Chemical 1]

In the urethane-modified (meth) acrylic resin, it is more effective to chemically bond the urethane resin and the (meth) acrylic resin component from the viewpoints of compatibility, liquid stability, film flexibility and the like. As a specific method, a reaction of a polymer in which a hydroxyl group is introduced into a (meth) acrylic polymer with β-hydroxyethyl methacrylate or the like and a urethane prepolymer having an isocyanate group at the molecular end or the following formula (2)

[0011]

[Chemical 2]

(In the formula, A is (meth) acrylic acid, (meth) acrylic acid ester monomer or (meth) (meth))
An acrylic acid ester oligomer is shown. ), It is synthesized by the reaction of a urethane prepolymer with a (meth) acryl component having a hydroxyl group at the molecular end (one end or both ends). In the polymer thus obtained, the urethane chain and the (meth) acrylic chain may be bonded to each other in a block type or a graft type. Further, by using several kinds of polyols and a bifunctional isocyanate [for example, HDI (hexamethylene diisocyanate)], a urethane prepolymer as a main chain is produced, and a mercapto group is contained in a side chain portion of the urethane prepolymer. Also, a method in which a (meth) acrylic monomer and a radical initiator are combined, a (meth) acrylic monomer is grafted to the urethane part, and the (meth) acrylic monomer is also polymerized at the same time for synthesis is often used. .

The method for obtaining the urethane-modified (meth) acrylic resin used in the present invention is not limited to the above-mentioned method, and other methods include adding a diisocyanate to a (meth) acrylic diol mixed system, (meth). It can also be obtained by a method of adding isocyanate polyester, polyether, etc. at both ends to an acrylic monomer and polymerizing the urethane acrylate. Further, as the (meth) (meth) acrylic resin component used in these syntheses, those having a glass transition temperature Tg as a polymer from room temperature to about 80 ° C. are preferable, and in addition to the above β-hydroxyethyl methacrylate, for example, , Ethyl methacrylate, isobutyl methacrylate, glycidyl methacrylate, etc. are used. (Meth) in the urethane-modified (meth) (meth) acrylic resin at this time
The composition of the acrylic resin component is preferably 5 to 80% by mass, particularly preferably 10 to 60% by mass, and further 20 to 5% by mass.
It is more preferably 0% by mass.

Further, from the viewpoint of improving the adhesion between the charging member and the photosensitive member, the urethane prepolymer may contain silicone. At this time, the silicone component is contained in the urethane prepolymer in an amount of 2 to 80% by mass, especially 5% by mass.
It is preferably contained in an amount of ˜50 mass%. Several kinds of (meth) acrylic monomers and high-molecular-weight polysiloxane-containing (meth) acrylic monomers having a molecular weight of 3000 or more are grafted to the side chains of these urethane prepolymers. In this case, the composition of the high molecular weight polysiloxane-containing (meth) acrylic monomer component in the urethane-modified (meth) acrylic resin is preferably 20% by mass or less, and particularly preferably 0.1 to 10% by mass. The reason for this is that if it is contained in excess, the resin solution may become cloudy or phase-separated, and even if it is contained in an amount of 20% by mass or more, the improvement effect is not improved. Moreover,
This is because unreacted high-molecular-weight polysiloxane (meth) acrylic monomer may become a contaminating component on the photoreceptor due to the problem of reactivity. The molecular weight of the polysiloxane of the high-molecular-weight polysiloxane-containing (meth) acrylic monomer is 3,000 or more, and particularly 5,000 to 2,000.
0 is preferred. The reason for this is that when the molecular weight is 3,000 or more, the effect of the present invention becomes remarkable, and even when it exceeds 20,000, the improving effect does not change, and conversely, the reactivity of the (meth) acrylic monomer becomes low. Because it will occur.

The high molecular weight polysiloxane-containing urethane-modified (meth) acrylic resin may be contained alone or in combination of two or more kinds in the surface layer of the charging member. Good. In this case, examples of the resin other than the urethane-modified (meth) acrylic resin include polyester, phenol resin, polyamide, epoxy resin, urea resin, urethane resin and the like. In some cases, the surface property can be further improved by adding an external additive such as a release agent to this surface layer. Further, by combining this external additive with silica particles, the adhesion to the photoreceptor may be further improved because the contact area is reduced. In this surface layer, the same conductive agent as above,
Preferred conductivity can be imparted by preferably adding carbon. The thickness of the surface layer is not particularly limited, but it is preferably 30 μm or less, particularly preferably 5 to 20 μm, and when it exceeds 30 μm, the resin layer becomes hard, so that the flexibility of the resin layer is impaired.

The urethane-modified (meth) acrylic resin is preferably used by containing an active hydrogen group at the terminal or side chain of the resin and crosslinking with a polyisocyanate compound or the like.
Polyisocyanate compound added as a crosslinking agent,
It is a compound having two or more isocyanate groups in the molecule, and the same polyisocyanate generally used as a raw material for producing polyurethane can be used. Specifically, tolylene diisocyanate (TD
I), diphenylmethane diisocyanate (MDI),
Naphthalene diisocyanate (NDI), tolidine diisocyanate (TODI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IP
DI), phenylene diisocyanate, xylylene diisocyanate (XDI), tetramethyl xylylene diisocyanate (TMXDI), cyclohexane diisocyanate, lysine ester triisocyanate, undecane triisocyanate, hexamethylene triisocyanate, triphenylmethane triisocyanate, and these isocyanate compounds. Examples include polymers, derivatives, modified products, hydrogenated products and the like. Among these, particularly aliphatic or alicyclic isocyanates such as hexamethylene diisocyanate and isophorone diisocyanate, and polymers, derivatives and modified products thereof are preferably used because they are excellent in ozone resistance and heat resistance.

The method for forming the resin layer is not particularly limited, but a coating solution containing each component for forming each layer is prepared, and the coating solution is applied by a dipping method or a spray method. The method is preferably used. In the resin layer of the present invention, the fluorine-containing urethane-modified (meth) acrylic resin used for the outermost layer may be either a water-based solvent or a solvent-based solvent, but in the case of a solvent-based solvent, smoothness is ensured, durability, and uniform charging are uniform. From the viewpoints of stability and production stability, it is preferable to sandwich one or more aqueous resin layers between the elastic layer and the elastic layer. The water-based resin may be of any type as long as the solvent is water, and includes water-soluble type, emulsion type, suspension type, etc., but especially carboxyl group, hydroxyl group,
A resin having an active hydrogen group such as an amino group is preferably used. Examples include polyester-based, (meth) acrylic-based, urethane-based, and hot water-soluble resins such as polydioxolane. Of these, the use of (meth) acrylic resin has a much smaller dielectric constant than urethane and nylon, which have been used as charging member resins in the past. Element/
It is preferable because the electric attraction and repulsion between the photoconductors are reduced and the charging noise is improved. Among the (meth) acrylic resins, those having a glass transition temperature of −50 to 10 ° C., a carboxyl group or hydroxyl group content of 2 to 5% by mass, and a soap-free emulsion type have a good crosslinking effect, and It is preferable because it has low hardness. In this middle layer,
A conductive agent may be added to give conductivity. The conductive agent is not limited, but carbon is particularly preferably used.

In this case, the carbon is not particularly limited, but the oxygen content is 5% by mass or more, particularly 7% by mass or more, further 9% by mass or more, and the pH is 5 or less.
It is preferable that it is 6 or more, particularly 7 or more. The oxygen content of ordinary carbon is about 0.1 to 3% by mass. Although there is some carbon that has been subjected to oxidation treatment, the carbon that has undergone this oxidation treatment tends to shift its pH to an acidic side as the oxygen content slightly increases, and the carbon is acidic. If so, the stability may decrease when added to the water-based resin. On the other hand, the carbon preferably used in the present invention is
Despite having a large oxygen content, it maintains neutrality or alkalinity and can be stably added to an aqueous resin. Further, those having a functional group such as a carboxyl group, a hydroxyl group or a ketone group on the carbon surface, and further, a part of hydrogen contained in these groups is replaced with an alkali metal such as sodium is preferably used.

The volume resistivity of the resin layer is 1 × 10 ³ to 1 ×.
10 ¹² Ω · cm, especially 1 × 10 ⁵ to 1 × 10 ¹⁰ Ω · cm
The amount of carbon added is usually 0.01 to 40% by mass, particularly about 5 to 20% by mass. In any configuration, the volume resistivity of the charging member of the present invention is 1 × 10 ^{3 in} order to obtain a good image.
˜1 × 10 ¹² Ω · cm is preferable, and particularly 1 ×
It is preferably 10 ⁵ to 1 × 10 ¹⁰ Ω · cm. Further, if the surface of the charging member has irregularities, the toner is clogged, which causes an image defect. Therefore, the surface of the charging member is preferably as smooth as possible. Specifically, the JIS ten-point average roughness Rz is preferable. It is preferably 4 μm or less, particularly 3 μm or less, and further preferably 2 μm or less (according to JIS-B0601).

The charging member of the present invention has a 1N (approx.
Cellulose 100 under a load of 100 gf)
%, 30 g / m², Coefficient of friction for 70 mesh cloth
Is less than 0.3. Below is the measurement method
To describe. The above friction coefficient is the friction test manufactured by Shinto Kagaku Co., Ltd.
Test machine "HEIDON Tribogear" is used and shown in Fig. 1.
The frictional resistance of the charging member was measured according to the method. In Figure 1
A movable stay in which the charging member 1 is provided on the base 2 as shown.
It is fixed to J3 and moved at a friction speed of 100 mm / min.
It was The opponent material of friction is 100% cellulose, 30 g /
m ², 70 mesh cloth (Bencot manufactured by Asahi Kasei Corporation)
Lint-free) 4 and load 1N with load 5
Rubbed as. The friction resistance at this time is the load cell 6
It was measured by. Cellulose 100 as a friction partner
%, 30 g / m²I chose the 70 mesh cloth because
It has the highest correlation with the surface property of the charging member, and
This is because it is suitable for enclosures.

Further, the charging member of the present invention has little toner adhesion, and there is not much difference in glossiness before and after image formation. Here, the surface glossiness was measured by the following method. That is, the haze gloss meter (manufactured by Big Gardner) is installed so that the uppermost surface of the charging member is the measurement surface. When the charging member is roller-shaped,
The length of the roller is adjusted to 10 cm, and the roller is fixed to a black fixing base that can be fitted according to the shape of the roller. Then, the surface glossiness is measured at an incident angle of 85 ° (measurement area 8 × 60 mm). In this case, the measured value is DIN67
A value obtained by setting the reflection index of 1.567 of the black glass standard plate according to 530 as the surface glossiness of 100 is obtained.

An example of the charging device of the present invention is shown in FIG.
As shown in FIG. 3, the charging roller 20 which is a charging member of the present invention is rotated while being driven while being brought into contact with the photosensitive drum 10 which is a member to be charged, and the voltage applying unit 30 causes a gap between the photosensitive drum 10 and the charging roller 20. In addition, a charging device configured to apply a DC voltage or a voltage obtained by superimposing an AC voltage on a DC voltage to charge the photosensitive drum 10 can be exemplified. The charging device to which the charging member of the present invention can be mounted is not limited to this, and the form of the member to be charged or the charging member or the voltage application method can be appropriately changed.

[0023]

EXAMPLES The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 A resin layer A having a thickness of 100 μm is formed on the surface of an elastic layer made of a conductive urethane foam having a density of 0.4 g / cm ³ , and a resin layer B having a thickness of 10 μm is further formed thereon.
Was formed to prepare a charging roller. The resin layer A was formed by applying a coating liquid in which carbon was added to an aqueous acrylic resin, and the volume resistivity was adjusted to 5 × 10 ⁷ Ω · cm. The resin layer B has an acrylic component of 50% by mass,
Furthermore, the molecular weight of all acrylic monomers is 10,000.
Urethane-modified acrylic resin containing 10% by mass of a high-molecular-weight polysiloxane-containing acrylic monomer including the polysiloxane of (the glass transition temperature Tg of the acrylic part is 27
(° C.) Was dissolved in MEK (methyl ethyl ketone) as a solvent, and an isocyanate crosslinking agent was added. The surface roughness of the obtained charging roller is JIS ten-point average roughness R.
The z value was 0.8 μm. This roller was set to a temperature of 22 ° C./humidity of 50% RH, cellulose of 100%, 30 g / m
^{When a} friction test was conducted by using the above-mentioned method using a ² , 70-mesh cloth, the friction coefficient was 0.12. Attach this roller to the printer cartridge and
When left at a temperature of 95 ° C./humidity of 95% RH for 2 weeks, no close contact with the photoreceptor (OPC) was observed. Further, when images were continuously printed on 10000 sheets using the cartridge, the images were not deteriorated. The surface glossiness before and after the image was output at the roller incident angle of 85 ° was measured by the above-mentioned method, and it was 43.5 before the image was output, but it was 42.3 after the image was output. Yes, there was almost no change before and after the image was displayed.

Example 2 A surface of an elastic layer made of conductive urethane foam having a density of 0.4 g / cm ³ and a thickness of 10
A resin layer A having a thickness of 0 μm is formed, and a thickness of 10 μm is further formed on the resin layer A.
A resin layer C of m was formed to prepare a charging roller. The resin layer A is formed by applying a coating liquid obtained by adding carbon to an aqueous acrylic resin, and has a volume resistivity of 5 × 10 ⁷ Ω.
・ Adjusted to cm. The resin layer C has an acrylic component of 50% by mass, and further contains 20% by mass of a high-molecular-weight polysiloxane-containing acrylic monomer containing polysiloxane having a molecular weight of 10,000 in all of the acrylic monomers (acrylic part). Glass transition temperature Tg of 80 ° C.) was dissolved in MEK as a solvent and an isocyanate crosslinking agent was added. The surface roughness of the obtained charging roller is 0.8 μm in terms of JIS ten-point average roughness Rz.
Met. This roller was subjected to a friction test under the conditions of temperature 22 ° C./humidity 50% RH using a cloth of 100% cellulose, 30 g / m ² , 70 mesh by the above-mentioned method, and the friction coefficient was 0.07. It was This roller is installed in the printer cartridge and the temperature is 40 ° C / humidity 95
When left at% RH for 2 weeks, no close contact with the photoreceptor was seen. In addition, 1 continuous using the cartridge
When 0000 images were printed, the images did not deteriorate. In addition, the incident angle of the roller before and after the image is output 8
When the surface glossiness at 5 ° was measured by the above-mentioned method, it was 45.8 before the image was output, but it was 45.0 after the image was output, and there was almost no change before and after the image was output. It was

[Embodiment 3] A thickness of 10 is formed on the surface of an elastic layer made of conductive urethane foam having a density of 0.4 g / cm ^3.
A resin layer A having a thickness of 0 μm is formed, and a thickness of 10 μm is further formed on the resin layer A.
A resin layer D having a thickness of m was formed to prepare a charging roller. The resin layer A is formed by applying a coating liquid obtained by adding carbon to an aqueous acrylic resin, and has a volume resistivity of 5 × 10 ⁷ Ω.
・ Adjusted to cm. The resin layer D contains 60% by mass of an acrylic component, and further contains 6% by mass of a high-molecular-weight polysiloxane-containing acrylic monomer containing polysiloxane having a molecular weight of 5000 in all the acrylic monomers. Glass transition temperature Tg of
Was dissolved in MEK as a solvent, and an isocyanate crosslinking agent was added. The surface roughness of the obtained charging roller was JIS 10-point average roughness Rz of 0.6 μm. This roller was subjected to a friction test under the conditions of a temperature of 22 ° C./humidity of 50% RH using a cloth of 100% cellulose, 30 g / m ² , 70 mesh, and the friction coefficient was 0.23. It was This roller is installed in the printer cartridge and the temperature is 40 ° C / humidity 95% R
When left in H for 2 weeks, no close contact with the photoreceptor was seen. In addition, the cartridge is used for continuous 100
When 00 images were output, the images did not deteriorate. In addition, the incident angle of the roller before and after image output is 85 °
When the surface glossiness at is measured by the above-mentioned method,
It was 50.5 before the image was displayed, whereas it was 50.1 after the image was displayed, and there was almost no change before and after the image was displayed.

[Comparative Example 1] A surface of an elastic layer made of a conductive urethane foam having a density of 0.3 g / cm ³ and having a thickness of 10
A resin layer A having a thickness of 0 μm is formed, and a thickness of 10 μm is further formed on the resin layer A.
A resin layer E of m was formed to prepare a charging roller. The resin layer A is formed by applying a coating liquid obtained by adding carbon to an aqueous acrylic resin, and has a volume resistivity of 5 × 10 ⁷ Ω.
・ Adjusted to cm. The resin layer E contains a urethane-modified acrylic resin (glass transition temperature Tg of acrylic part is 27 ° C.) containing 50% by mass of an acrylic component and containing no fluorine or silicone as an acrylic monomer, and a solvent ME.
It was dissolved in K and an isocyanate crosslinking agent was added. The surface roughness of the obtained charging roller was 0.7 μm in terms of JIS ten-point average roughness Rz. The temperature of this roller is 22 ℃
/ Humidity 50% RH, 100% cellulose, 30
When a friction test was conducted by using the above-mentioned method using a 70-mesh cloth having g / m ² , the friction coefficient was 2.5. When this roller was attached to the printer cartridge and left for 2 weeks at a temperature of 40 ° C./humidity of 95% RH,
Adhesion with the photoconductor occurred. Further, when continuous image output was performed using the cartridge, image deterioration due to toner adhesion to the charging roller was observed at the time of printing 2000 sheets. Further, the surface glossiness before and after the image is output at the incident angle of the roller of 85 ° was measured by the above-mentioned method.
After the image was displayed, it was 27.9, and the surface glossiness was greatly reduced.

[Comparative Example 2] On the surface of an elastic layer made of conductive urethane foam having a density of 0.4 g / cm ³ , a thickness of 10 was obtained.
A resin layer A having a thickness of 0 μm is formed, and a thickness of 10 μm is further formed on the resin layer A.
A resin layer F of m was formed, and a charging roller was produced. The resin layer A is formed by applying a coating liquid obtained by adding carbon to an aqueous acrylic resin, and has a volume resistivity of 5 × 10 ⁷ Ω.
・ Adjusted to cm. In the resin layer F, a urethane-modified acrylic resin (glass transition temperature Tg of acrylic part is 80 ° C.) containing 50% by mass of an acrylic component and containing no fluorine or silicone as an acrylic monomer is used as a solvent ME.
It was dissolved in K and an isocyanate crosslinking agent was added. The surface roughness of the charging roller thus obtained was 0.8 μm in terms of JIS ten-point average roughness Rz. The temperature of this roller is 22 ℃
/ Humidity 50% RH, 100% cellulose, 30
When a friction test was conducted by using the above-mentioned method using a 70 / mesh g / m ² cloth, the friction coefficient was 1.1. When this roller was attached to the printer cartridge and left for 2 weeks at a temperature of 40 ° C./humidity of 95% RH,
Adhesion with the photoconductor occurred. Furthermore, when continuous image output was performed using the cartridge, image deterioration due to toner adhesion to the charging roller was observed at the time of printing 5000 sheets. In addition, when the surface glossiness at the incident angle of the roller of 85 ° before and after the image is output is measured by the above-described method, it is 57.0 before the image is output,
It was 44.5 after the image was displayed, and the surface glossiness was greatly reduced.

[Comparative Example 3] A layer having a thickness of 10 was formed on the surface of an elastic layer made of a conductive urethane foam having a density of 0.4 g / cm ^3.
A resin layer A having a thickness of 0 μm is formed, and a thickness of 10 μm is further formed on the resin layer A.
A resin layer G of m was formed to prepare a charging roller. The resin layer A is formed by applying a coating liquid obtained by adding carbon to an aqueous acrylic resin, and has a volume resistivity of 5 × 10 ⁷ Ω.
・ Adjusted to cm. The resin layer G has an acrylic component of 50% by mass, and further contains 40% by mass of a polysiloxane-containing acrylic monomer containing polysiloxane having a molecular weight of 1000 in all the acrylic monomers. The transition temperature Tg is 27
(° C.) Was dissolved in MEK as a solvent, and an isocyanate crosslinking agent was added. The surface roughness of the charging roller thus obtained was 0.8 μm in terms of JIS ten-point average roughness Rz.
A friction test was conducted on this roller at a temperature of 22 ° C./humidity of 50% RH by using the cloth of 100% cellulose, 30 g / m ² , 70 mesh by the above-mentioned method.
The coefficient of friction was 0.49. When this roller was mounted on a printer cartridge and left at a temperature of 40 ° C./humidity of 95% RH for 2 weeks, no close contact with the photoconductor was observed. Furthermore, when continuous image output was performed using the cartridge, image deterioration due to toner adhesion to the charging roller was observed at the time of printing 5000 sheets. Also, the surface glossiness before and after image output at the roller incident angle of 85 ° was measured by the above-mentioned method. As a result, it was 54.5 before image output, but 40.3 after image output. Yes, the surface glossiness was greatly reduced.

[0029]

EFFECT OF THE INVENTION The charging member of the present invention does not easily adhere to the photosensitive member, has little friction, is free from toner adhesion, and has excellent charging characteristics and charging environment stability. A good image can be obtained by mounting the apparatus on the image forming apparatus.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a method for measuring a friction coefficient of a charging member.

FIG. 2 is a schematic view showing an example of a charging device of the present invention.

[Explanation of symbols]

10 Photosensitive drum 20 charging roller 30 voltage applying means

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H200 FA18 FA19 HA03 HA28 HB12                       HB13 HB14 HB43 HB45 HB46                       HB47 LA18 LC03 LC04 MA03                       MA04 MA08 MA14 MA17 MA20                       MB04 MC05 MC06 MC11 MC20                 4F100 AK01B AK25B AK51A AK51B                       AK52B AL06B BA02 CA02B                       DE01B DJ01B EH46 GB48                       JA07B JA13A JB05 JG01B                       JG03 JK07A JK16B JL14                       JL16 YY00B                 4J026 AB02 BA26 BA50 BB03 BB10                       FA09 GA01 GA08 GA10

Claims (8)

[Claims] 1. A charging member for charging a member to be charged by contacting the member to be charged and applying a voltage between the member and the member to be charged, wherein the charging member comprises an elastic layer and at least one resin layer. A charging member comprising a layer, wherein the resin layer is formed of a resin containing 20 mass% or less of a polysiloxane-containing (meth) acrylic monomer. 2. A resin forming a resin layer contains 5 to 80% by mass of a (meth) acrylic resin component, and 40% by mass or less of the (meth) acrylic resin component is a poly (meth) acrylic monomer. The charging member according to claim 1, which is a urethane-modified (meth) acrylic resin containing siloxane. 3. A urethane-modified (meth) acrylic resin,
The charging member according to claim 2, wherein the polysiloxane-containing (meth) acrylic monomer has a polysiloxane molecular weight of 3000 or more. 4. The charging member according to claim 1, wherein the resin layer contains a bifunctional or higher functional isocyanate crosslinking agent. 5. The charging member according to claim 1, wherein the resin layer contains a conductive powder. 6. The elastic layer has a density of 0.05 to 0.9 g / cm ^3.
The charging member according to any one of claims 1 to 5, which is made of the urethane foam. 7. The charging member has a coefficient of friction of 0.3 or less against a cloth of 100% cellulose, 30 g / m ² , 70 mesh when a load of 1 N is applied.
The charging member according to any one of 1. 8. A charging device comprising: a charging member that contacts a member to be charged to charge the member to be charged; and a voltage applying unit that applies a voltage between the member to be charged and the charging member. A charging device comprising the charging member according to claim 1 as a charging member.