JP2002089544A - Conductive roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve good toner releasability of a conductive roller by assuring the uniformity of the surface resistance of the roller without reducing the surface roughness and the surface hardness of the roller. SOLUTION: The conductive roller 1 is provided which includes a roller base material 3 having formed on its surface an urethane resin coating layer 4 containing conductive powders dispersed therein and also containing a fluorine surfactant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive roll used for a charging roll of an electrophotographic apparatus, for example.

[0002]

2. Description of the Related Art This type of charging roll is required to have a surface having good toner releasability. Conventionally, in order to impart good toner releasability to the roll surface, a configuration in which a fluororesin powder is dispersed in a conductive coating layer on the surface has been provided (Japanese Patent Application Laid-Open No. Hei 3-212672).

[0003]

However, in the above-described conventional structure, when the fluororesin powder is dispersed in the coating layer, the uniform dispersion of the conductive powder is hindered, and the surface resistance of the roll is varied. When dispersed, the surface roughness increases, and the toner is trapped in the unevenness on the surface, and the toner releasability is impaired. Further, when the fluororesin powder is dispersed in the coating layer, the coating layer becomes high in hardness, and in combination with the increase in surface roughness, abrasion of the photoreceptor surface rubbed by the charging roll or generation of noise when rubbing occurs. Problems also arise.

[0004]

According to the present invention, as a means for solving the above-mentioned conventional problems, a roll base material (3) is provided on a surface thereof.
An object of the present invention is to provide a conductive roll (1) in which a conductive powder is dispersed and a urethane resin coating layer (4) containing a fluorine-containing surfactant is formed.

It is desirable that the fluorine-based surfactant and the urethane resin have active hydrogen, and that the fluorine-based surfactant be bound to the urethane resin via a polyisocyanate.

Further, it is desirable that the roll base material (3) is made of urethane foam resin in which conductive powder is dispersed.

[0007]

In the conductive roll (1) of the present invention, when the fluorine-containing surfactant contains a hydroxyl group in the process of forming the urethane resin coating layer (4), it is formed by reacting with the polyisocyanate. Since the fluorine-based surfactant binds to the urethane resin to be formed, the fluorine-based surfactant is completely prevented from being breathed from the urethane resin coating layer (4).

Further, in the urethane resin coating layer (4), the side chain of the fluorinated alkyl group contained in the fluorosurfactant is oriented on the surface of the coating layer (4) to obtain good water repellency ( Release property) on the surface, and the resin-affinity side chains are oriented in the urethane resin layer, so that good compatibility is provided.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below. FIG. 1 shows an embodiment of the roll (1) of the present invention.
(1) is a cylindrical roll substrate (3) having a shaft (2) at the center
And a urethane resin coating layer (4) formed on the surface of the roll substrate (3). The shaft (2) is in the form of a rod or pipe made of, for example, aluminum, stainless steel or the like.

[Roll base material] As the material of the roll base material (3), for example, urethane resin, thermoplastic elastomer, epichlorohydrin rubber, ethylene-propylene-
Resin materials such as diene copolymer rubber, silicone rubber, acrylonitrile-butadiene copolymer rubber, and polynorbornene rubber are used singly or as a mixture of two or more, and a preferable material is urethane foam resin. As the urethane foam resin, a urethane-based resin obtained by mixing and dispersing a hollow body such as a hollow glass bead or a heat-expandable microcapsule to impart a closed cell structure is desirable.Such a urethane foam resin is a charging roll (1 ) Has desirable low hardness elasticity, and the urethane resin coating layer (4)
And good adhesion is secured between them.

As the hollow glass beads mixed and dispersed in the roll substrate (3), hollow glass beads made of borosilicate glass are particularly desirable. The average particle size of the hollow glass beads is about 20 to 60 μm, but a desirable particle size is about 40 μm.

The thermally expandable microcapsules to be mixed and dispersed in the roll substrate (3) include isobutane (boiling point -12 ° C.), normal butane (boiling point -5 ° C.), ethyl methyl ether (boiling point 7 ° C.), isopentane (Boiling point 2
7.85 ° C.) and the like, and a liquid resin having a boiling point in the range of −15 ° C. to 30 ° C. is filled in a thermoplastic resin capsule. The thermoplastic resin is desirably hardly soluble or insoluble in the above-mentioned solvent, and has a softening point of 200 or less.
C. or less is desirable. To make the thermoplastic resin hardly soluble or insoluble in the solvent, for example, acrylonitrile,
A nitrile vinyl monomer such as methacrylonitrile is copolymerized. Desirable thermoplastic resins include, for example, methyl methacrylate-acrylonitrile copolymer and methyl methacrylate-acrylonitrile-methacrylonitrile copolymer. The average particle size of the microcapsules is usually about 10 to 20 μm, and about 50 to 12 μm by heating.
One that expands to 0 μm (the volume is 4 when fully expanded)
And usually 0.5 to 3.0% by weight is added to the urethane resin composition. The heat-expandable microcapsules are added to the urethane resin composition in an unexpanded state, a heat-expanded state, or a mixture of an unexpanded state and a heat-expanded state.

Further, in order to impart conductivity to the roll base material (3), carbon black, graphite, potassium titanate, iron oxide, conductive titanium oxide, conductive zinc oxide, conductive tin oxide, etc. Ionic conductive agents such as quaternary ammonium salts, borates, and surfactants, alone or in combination of two or more.

[Urethane Resin Coating] The urethane resin used in the urethane resin coating of the present invention is preferably a polyester urethane resin containing polyisocyanate and polyester polyol as main components, and more preferably a free hydroxyl group is present (ie, active). (With hydrogen) polyester urethane resin. Examples of the polyisocyanate include tolylene diisocyanate (TDI), 4,4′-
Diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HMDI), meta-xylylene diisocyanate (XDI), hydrogenated TDI, hydrogenated MD
I and the like, there is a polyisocyanate compound obtained by the reaction of the diisocyanate and the monomeric triol, or a polyisocyanate derived from these diisocyanates, and as the polyester polyol, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid,
Polybasic acids such as adipic acid, dimerized linoleic acid and maleic acid and / or metal sulfonic acids such as 5-sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, 2-sodium sulfoisophthalic acid and 2-potassium sulfoisophthalic acid Polybasic acid containing a base, glycol or diol such as ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, 2-methyl-1,3-propanediol, trimethylolpropane, hexanetriol, glycerin, trimethylolethane, pentane A polyester polyol produced from a hydroxyl compound such as erythritol is mainly used, and other polyethers such as polyethoxypropylene glycol and poly (oxypropylene) triol; Machine oil, alone acrylic polyols, or by mixing two or more kinds, or may be used together with the polyester polyol.

The above-mentioned polyester urethane resin is usually in the form of an organic solvent solution such as toluene, xylene, ethyl acetate, butyl acetate, methyl ethyl ketone, and methyl isobutyl ketone. Such polyester urethane resins are described in, for example, JP-A-6-263981, JP-A-6-2639.
No. 82, JP-A-6-287268, JP-A-6-287268
The details are described in, for example, JP-A-287441 and JP-A-9-40738.

[0016] The urethane resin coating material includes the above-mentioned roll base material.
The same conductive powder or ionic conductive agent as used in (3) is usually added in an amount of 0.1 to 30.0% by weight based on the resin, and a fluorine-based surfactant is generally added to the resin. 0.6 to 2.0% by weight is added.

The fluorinated surfactant used in the present invention is not particularly limited as long as it contains fluorine in the molecule. In particular, the fluorinated surfactant containing a fluorinated alkyl group-containing ethylenically unsaturated monomer can be used. Polymer containing a fluorinated alkyl group-containing ethylenically unsaturated monomer and an ethylenically unsaturated monomer having a short silicone chain; There is a polymer or the like containing a hydrophilic structural unit-containing ethylenically unsaturated monomer such as an alkylene group, and two or more kinds of the above-mentioned fluorine-based surfactants may be used in combination. Desirable fluorine-based surfactants include those containing a functional group having an active hydrogen such as a hydroxyl group or a carboxyl group. Such fluorine-based surfactants are described in, for example, JP-A-10-230154 and
JP-A-309455, JP-A-10-330683, JP-A-11-209787, JP-A-2000
-27772, JP-A-2000-102727, and the like.

[Resistor Adjusting Intermediate Layer] In the roll (1) of the present invention, the surface electric resistance of the roll (1) is adjusted between the roll substrate (3) and the urethane resin coating layer (4). For this purpose, a resistance adjusting intermediate layer (5) may be interposed. To form the resistance adjusting intermediate layer (5), one or two or more thermoplastic resins or thermosetting resins such as urethane resin, polyester resin, melamine resin, epoxy resin, acrylic resin, polyamide resin, or epichlorohydrin rubber One or two or more rubbers such as ethylene-propylene-diene rubber, silicone rubber, acrylonitrile-butadiene copolymer rubber, and polynorbornene rubber; or one or more of the above resins and one or two of the above rubbers A solution prepared by dissolving the above mixture in an organic solvent or the like and mixing the above-mentioned conductive powder with the solution is applied and dried. The thickness of the resistance adjusting intermediate layer (5) is usually 1 to 30 μm.

[Formation of Urethane Resin Coating Layer] In the present invention, in order to form the urethane resin coating layer (4) on the roll base material (3) or the resistance adjusting intermediate layer (5), the urethane resin coating layer is used. The above-mentioned conductive powder and the fluorine-based surfactant are further added and mixed to the coating material, and further, when the fluorine-based surfactant and the urethane resin have active hydrogen, a polyisocyanate is added and mixed, and the surface of the roll base material (3) is mixed. Alternatively, it is applied on the resistance adjusting intermediate layer (5) and, if desired, is dried and cured by heating. The coating is usually performed by dipping, spray coating, brush coating, or the like, and the heating conditions for heating and drying are usually 50 to 120 ° C. and 0.5 to 24 hours. The thickness of the urethane resin coating layer (4) is usually 5 to 100 μm.

In the process of forming the urethane resin coating layer (4), the urethane resin has a free hydroxyl group, that is, a functional group having active hydrogen, and the fluorine-containing surfactant has a functional group having active hydrogen such as a hydroxyl group or a carboxyl group. Is contained, the fluorine-based surfactant is bonded to the urethane resin by reacting with the polyisocyanate. Therefore, it is completely required that the fluorine-based surfactant be breathed from the urethane resin coating layer (4). Is prevented.

In the urethane resin coating layer (4), the fluoroalkyl side chain contained in the fluorosurfactant is oriented on the surface of the coating layer (4) to provide good water repellency (releasability). On the surface, and the resin lipophilic side chains are oriented in the urethane resin layer to give good compatibility.

[Embodiment] In the conductive roll (1) shown in FIG. 1, an aluminum pipe was used as the shaft body (2).
As materials for the roll substrate (3), hollow glass beads (Fuji Balloon S-45, manufactured by Fuji Serial Chemical Co., Ltd., hollow borosilicate glass having an average particle diameter of about 40 μm) and thermal expansion type microcapsules (EXPANCEL 051DE, EX A urethane foam resin mixed and dispersed with an average particle diameter of about 50 μm manufactured by Pancel Co., Ltd. was used.

The urethane resin paint is a polyester urethane resin (Vylon UR8700, manufactured by Toyobo), polyisocyanate (Coronate HX, manufactured by Nippon Polyurethane Industry), carbon black (# 990, manufactured by Mitsubishi Chemical) and a fluorine-based surfactant (DEFENSA MCF). −32
3, manufactured by Dainippon Ink and Chemicals, Inc.) at 970: 160: 6
It is blended in a weight ratio of 7.8: 15 and is manufactured by stirring with a stirrer.

The roll substrate (3) is set on a dipping machine filled with the urethane resin paint, and the roll substrate (3) is moved up and down to perform dipping.
The urethane resin paint was applied to the surface of (3).

The roll substrate (3) coated with a urethane resin paint on the surface is then subjected to 0.5 hours at 100 ° C. and 2 hours at 60 ° C.
The urethane resin coating material was cured by heat treatment in an air atmosphere for 4 hours to form a urethane resin coating layer (4) on the surface of the roll substrate (3). The thickness of the urethane resin coating layer (4) was 30 μm. In this embodiment, the resistance adjusting intermediate layer (5) is not formed.

The contact angle, increase in hardness *, and surface roughness Ra of the conductive roll (Example) obtained as described above were measured. The results are shown in Table 1. * Hardness increase = Hardness (with coating layer)-Hardness (without coating layer) Further, the volume resistance value of the conductive roll (Example) was measured at 36 points in the circumferential direction, and the results are shown in FIG.

Comparative Example In contrast to the above example, the urethane resin paint was a polyester urethane resin (Vylon UR).
8700, manufactured by Toyobo, polyisocyanate (Coronate HX, manufactured by Nippon Polyurethane Industry), carbon black (# 990, manufactured by Mitsubishi Chemical Corporation), and fluororesin powder (Teflon (registered trademark) powder) at 970: 160: 67.
It is blended at a weight ratio of 8: 113 and is manufactured by stirring with a stirrer.

In the same manner as in the example, the urethane resin coating was applied to the surface of the roll substrate (3) and cured by heating to form a urethane resin coating layer (4).

The contact angle, hardness increase *, and surface roughness Ra of the conductive roll (comparative example) obtained as described above were measured, and the results are shown in Table 1. * Hardness increase = Hardness (with coating layer)-Hardness (without coating layer) Further, the volume resistance value of the conductive roll (Comparative Example) was measured at 36 points in the circumferential direction, and the results are shown in FIG.

[0030]

[Table 1]

According to Table 1, the contact angle (toner separation) of the conductive roll mixed with the fluorine-based surfactant (Example) was larger than that of the conductive roll mixed with the fluororesin powder (Comparative Example). It can be seen that the moldability is good), the rise in hardness is small, and the surface roughness is small. According to the graphs of FIGS. 2 and 3, the conductive roll mixed with the fluorine-based surfactant (Example) has a higher volume resistance value than the conductive roll mixed with the fluororesin powder (Comparative Example). It can be seen that the uniformity of is maintained.

[0032]

According to the present invention, good toner releasability can be obtained by ensuring uniformity of surface resistance without deteriorating the surface roughness and surface hardness of the conductive roll.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a conductive roll in the present embodiment.

FIG. 2 is a graph of a volume resistance value of a conductive roll in the present embodiment.

FIG. 3 is a graph of a volume resistance value of a conductive roll in a comparative example.

[Explanation of Signs] 1 Conductive Roll 2 Shaft 3 Roll Base 4 Urethane Resin Coating Layer 5 Resistance Adjustment Intermediate Layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 21/00 C08L 21/00 75/04 75/04 G03G 15/02 101 G03G 15/02 101 F term ( 2H003 BB11 CC05 3J103 AA02 AA15 AA23 AA24 AA33 AA41 AA51 BA31 BA41 FA02 FA07 FA18 GA02 GA52 HA01 HA03 HA04 HA05 HA15 HA18 HA20 HA33 HA37 HA41 HA48 HA54 4F006 AA04 AA14 AA37 AB37 AB72 AB73 AB74 BA07 CA08 DA04 CK021 CP031 DA026 DA036 DE096 DE106 DE116 DE136 DE186 DK006 EN136 FD116 FD312

Claims (3)

[Claims] 1. A conductive roll comprising a roll base material and a urethane resin coating layer containing a fluorine-containing surfactant and a conductive powder dispersed therein. 2. The conductive material according to claim 1, wherein the fluorine-based surfactant and the urethane resin have active hydrogen, and the fluorine-based surfactant is bonded to the urethane resin via a polyisocyanate. Sex roll. 3. The conductive roll according to claim 1, wherein the roll base is made of a urethane foam resin in which conductive powder is dispersed.