JP5654063B2 - Conductive roller - Google Patents

Description

  The present invention relates to a conductive roller.

  In general, in an image forming apparatus using an electrophotographic system such as a copying machine, a printer, and a facsimile, a transfer roller, a developing roller, and a toner supply in each process of image formation such as development, charging, and transfer (toner supply and cleaning). A roller having conductivity, such as a roller, a charging roller, a cleaning roller, an intermediate transfer roller, and a belt driving roller, is used.

  These conductive rollers have a structure in which an elastic layer made of conductive rubber, a polymer elastomer, a polymer foam, or the like, which has been provided with conductivity by blending a conductive agent, is formed on the outer periphery of a shaft as a rotating shaft. In order to obtain desired surface roughness, conductivity, hardness, etc., a basic structure is used in which a coating film is formed on the outer periphery of the elastic layer.

  In order to prevent deterioration of durability, there is a conductive roller having a surface layer cured with an isocyanate compound. A surface treatment solution in which a water-soluble isocyanate compound is dispersed or dissolved in a solvent mainly composed of water in order to improve the working environment that becomes a problem when an organic solvent is used for the curing treatment and to preserve the global environment. There is a conductive roller used (Patent Document 1).

JP 2003-138045 A

  The surface layer needs to satisfy various characteristics such as surface roughness, conductivity, hardness, durability, and appearance. Therefore, the conductive roller surface layer is often formed from a plurality of layers having different characteristics. Of the multiple layers, a layer for adjusting the resistance and hardness of the conductive roller was formed by applying and drying an aqueous solvent without using an organic solvent in order to improve the working environment and preserve the global environment. In the conductive roller, the surfactant contained in the layer for resin dispersion and the conductive agent contained in the layer for resistance adjustment are diffused when the conductive roller is used in a hot and humid environment. May ooze out to the surface of the conductive roller. As a result, a member that contacts the conductive roller in the electrophotographic apparatus, such as an organic photoreceptor, may be adversely affected by the surfactant or ions, and image defects may occur.

  As a result of intensive studies by the inventor to solve the above-mentioned problems, the surface layer of the conductive roller is coated with a water-based paint containing a crosslinking agent of a blocked isocyanate compound, so that the surfactant and the conductive agent are diffused. The inventors have found that the problem can be prevented and have completed the present invention.

  The conductive roller of the present invention based on the above knowledge includes a shaft, an elastic layer formed on the outer periphery of the shaft, and a surface layer formed on the outer peripheral surface of the elastic layer, and the surface layer is a water-based paint. And the outermost layer is formed by coating and curing an aqueous paint containing a crosslinking agent of a blocked isocyanate compound, and the outermost aqueous paint is an acrylic, It is one type or two or more types of resins selected from urethane type, acrylic urethane type and fluorine type.

  In the conductive roller of the present invention, the outermost layer preferably has a thickness of 1 to 30 μm, the block isocyanate compound is preferably a hydrophilic group-containing aliphatic block polyisocyanate, and further, The ratio to the water-based paint is preferably in the range of 0.2 to 1.5 equivalents.

  According to the present invention, the outermost layer of the plurality of surface layers is formed by coating and curing a water-based paint containing a crosslinking agent of a blocked isocyanate compound. It became possible to prevent the conductive agent from diffusing.

It is sectional drawing which shows an example of the electroconductive roller which concerns on suitable embodiment of this invention. It is an expanded sectional view of the surface layer vicinity of the conductive roller which concerns on suitable embodiment of this invention.

DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
In the sectional view of an example of the conductive roller according to the embodiment of the present invention shown in FIG. 1, the conductive roller 10 of the present invention includes a shaft 11, an elastic layer 12 formed on the outer periphery of the shaft 11, and an elastic layer 12. And a surface layer 13 formed on the outer peripheral surface of.

  The surface layer 13 is composed of a plurality of layers as shown in the enlarged sectional view of FIG. In the example of FIG. 2, the surface layer 13 includes an intermediate layer 13a in contact with the elastic layer 12, and an outermost layer 13b in contact with the intermediate layer 13a. However, the conductive roller 10 is not limited to the example in which the surface layer 13 is shown in FIG. 2, and may have a structure of three or more layers. The intermediate layer 13 a is a layer mainly for adjusting the resistance and hardness of the conductive roller 10, and the outermost layer 13 b is a layer for mainly adjusting the surface roughness of the conductive roller 10.

  The intermediate layer 13a and the outermost layer 13b are formed by applying and drying a water-based paint. The aqueous paint used for the intermediate layer 13a and the outermost layer 13b is an emulsion in which a resin is dispersed in an aqueous solvent, and a surfactant is included for the dispersion of the resin. In addition, a conductive agent is appropriately added to the water-based paint of the intermediate layer 13a for resistance adjustment. Since the water-based paint is used, the influence on the environment can be extremely reduced as compared with the organic solvent system.

  In the conductive roller 10 of this embodiment, the outermost layer 13b is formed by applying and drying a water-based paint containing a crosslinking agent of a blocked isocyanate compound. The outermost layer 13b is obtained by applying and drying a water-based paint containing a cross-linking agent of a blocked isocyanate compound, so that the outermost layer 13b is obtained after drying despite being formed using the water-based paint. The coated film is dense. Therefore, even if the surfactant or conductive agent diffuses from the elastic layer 12 or the intermediate layer 13a and reaches the outermost layer 13b, it can be prevented from moving to the surface of the outermost layer 13b.

  When the water-based paint for forming the outermost layer is a non-blocking type isocyanate compound cross-linking agent, the surface of the conductive roller 10 is exposed to a surfactant or the like on the surface of the conductive roller 10 in about several days, for example, with the passage of time after blending the paint. The effect of preventing ions from appearing is reduced. This is presumably because with the crosslinking agent of the non-block type isocyanate compound, the isocyanate was deactivated over time and the crosslinking reaction did not proceed.

  The resin to be crosslinked with the blocked isocyanate compound is preferably one or more resins selected from acrylic, urethane, acrylurethane, fluorine, and the like. Of these, a fluorine-based resin is preferable.

  The ratio of the blocked isocyanate compound to the water-based paint is preferably in the range of 0.2 to 1.5 equivalents. If the ratio with respect to the water-based paint is small, the effect of including the blocked isocyanate compound is poor, and if the ratio with respect to the water-based paint is too large, there is a disadvantage that the toner component tends to adhere and an image defect occurs.

  The thickness of the outermost layer 13b is preferably in the range of 1 to 30 μm. The effect of the present invention can be obtained even if the thickness is 1 μm, but if it is less than 1 μm, the durability of the conductive roller may not be sufficient. On the other hand, if it exceeds 30 μm, good surface properties may not be obtained such as adversely affecting the charging characteristics, dripping during dipping coating, or wrinkling of the surface. A more preferable range is 3 to 30 μm.

  Examples of the water-based paint that can be used for the intermediate layer 13a of the surface layer 13 include one or more selected from the group consisting of rubber, urethane, fluorine, and acrylic. As rubber type, natural rubber (NR), chloroprene rubber (CR), nitrile rubber (NBR), latex such as styrene butadiene rubber (SBR), etc., as urethane type, emulsion and dispersion such as ether type, ester type, As the fluororesin emulsion and acrylic, emulsions such as acrylic and acrylic styrene can be suitably used.

  For the water-based paint of the intermediate layer 13a of the surface layer 13, the same or different type of crosslinking agent as the outermost layer crosslinking agent can be used. Although it does not specifically limit as a crosslinking agent, For example, oxazoline type crosslinking agents, such as an oxazoline group containing styrene-acryl copolymer, can be mentioned. Any oxazoline-based cross-linking agent can be used as long as it is water-soluble, but those having two or more oxazoline groups are preferred, and in particular, the oxazoline group equivalent is 300 to 1000, and Tg = -50 degreeC-50 degreeC can be used suitably. If the oxazoline group equivalent exceeds 1000, the molecular weight becomes large and handling at room temperature becomes difficult. On the other hand, if it is less than 300, the reactivity is too high and gelation occurs, so neither is preferred. The compounding quantity of this oxazoline type crosslinking agent can be 5-50 mass parts with respect to 100 mass parts of aqueous acrylic resins.

  A conductive agent can be appropriately added to the water-based paint for the intermediate layer 13a to impart conductivity. Examples of the conductive agent include an ionic conductive agent and an electronic conductive agent. Examples of the ionic conductive agent include tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium (for example, lauryltrimethylammonium), hexadecyltrimethylammonium, and octadecyltrimethyl. Perchlorates such as ammonium (eg stearyltrimethylammonium), benzyltrimethylammonium, modified fatty acid dimethylethylammonium, chlorate, hydrochloride, bromate, iodate, borofluoride, sulfate, ethyl Ammonium salts such as sulfates, carboxylates and sulfonates, perchlorates, chlorates, hydrochlorides and odors of alkali metals and alkaline earth metals such as lithium, sodium, potassium, calcium and magnesium Salts, iodate salts, fluoroboric acid salts, trifluoromethyl sulfate, and sulfonic acid salts. Examples of the electronic conductive agent include conductive carbon such as ketjen black and acetylene black; carbon for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT; for ink subjected to oxidation treatment Examples thereof include carbon, pyrolytic carbon, natural graphite, and artificial graphite; conductive metal oxides such as tin oxide, titanium oxide, and zinc oxide; metals such as nickel, copper, silver, and germanium. These conductive agents may be used alone or in combination of two or more.

  Other vulcanizing agents, vulcanization accelerators, anti-aging agents, and the like can be appropriately added to the water-based paint of the intermediate layer 13a and the outermost layer 13b of the surface layer 13 as desired.

  In the present invention, the coating method for forming the intermediate layer 13a and the outermost layer 13b of the surface layer 13 is not particularly limited, but usually the above water-based paint is prepared and applied by dipping method, spray method, roll coater method, die coating method or the like. Then, a method of drying and solidifying is adopted.

  Further, the thickness of the intermediate layer 13a is set according to the form of the conductive roller 10 and the like, and is not particularly limited, but is usually 10 to 500 μm, particularly 30 to 350 μm, and if it is less than 10 μm, The durability may be inferior. On the other hand, if the thickness exceeds 500 μm, good surface properties may not be obtained, such as adversely affecting the charging characteristics or causing wrinkles on the surface.

The elastic body forming the elastic layer 12 is not particularly limited, and can be formed of a known rubber or resin, or a foam body in which closed cells are dispersed. Specifically, rubbers having base rubbers such as 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 polyurethane foam is more preferably used. In this case, the foaming ratio of the polyurethane foam is not particularly limited, but is preferably 1.2 to 50 times, particularly preferably about 1.5 to 10 times, and the foam density is suitably about 0.1 to 0.7 g / cm ^3. It is.

  By adding a conductive agent to the elastic layer 12, conductivity can be imparted or adjusted to a predetermined resistance value. The conductive agent is not particularly limited.

  In addition to the above conductive agent, the elastic layer 12 may include a thickener, an antifoaming agent, a leveling agent, a dispersant, a thixotropic agent, a wetting agent, an antiblocking agent, a cross-linking agent, and a film as necessary. An appropriate amount of known additives such as auxiliaries can be blended.

  The thickness of the elastic layer 12 is preferably 1.0 to 5.0 mm, and more preferably 1.0 to 3.0 mm. By setting the thickness of the elastic layer 2 in such a range, spark discharge can be prevented.

  The shaft 11 is made of metal or plastic, and a hollow cylindrical body or solid cylindrical body can be used.

  The shaft 1 is a metal or resin bar, and is a member that serves as a rotating shaft of the conductive roller 10. An elastic layer is formed around the shaft 1.

  The outermost layer of the conductive roller of the present invention is formed by applying and drying a water-based paint containing a crosslinking agent of a blocked isocyanate compound, thereby preventing contamination from the elastic layer and the intermediate layer over a long period of time. What can be done will be clarified by examples.

  Three types of water-based paints for the outermost layer having different formulations with different crosslinking agent components shown in Table 1 were prepared. In addition, the mixture ratio in a table | surface is a weight part.

※1
水分散フッ素系樹脂：FE4400（旭硝子（株））
※2
シリコーングラフトアクリル樹脂：サイマックUS-450（東亜合成（株））
※3
顔料に親和性のある基を有する高分子量ブロック共重合体の水溶液：DISPERBYK-190（ビックケミー・ジャパン（株））
※4
ポリアミドアミン塩：TW-124（伊藤製油（株））
※5
過塩素酸塩：KS-555（花王（株））
※6
鉱油、ポリエーテル、疎水性シリカ、水等の混合物：SNデフォーマー 777（サンノプコ（株））
※7
親水性基含有脂肪族ブロックポリイソシアネート：バイヒジュール2310（住化バイエルウレタン（株））
※8
親水性基含有脂肪族ブロックポリイソシアネート：DP9C/214（（株）GSIクレオス）
※9
親水性基含有脂肪族ポリイソシアネート：バイヒジュール3100（住化バイエルウレタン(株)）
※10
架橋ポリメタクリル酸メチルの真球状微粒子：MBX-8（積水化成工業（株））
※11
黒色有機顔料の水系分散液：BONJET BLACK CW-1（オリヱント化学(株)）
※12
黒色有機顔料の水系分散液：BSYD-15007（御国色素（株））
※13
精製水

* 1
Water-dispersed fluororesin: FE4400 (Asahi Glass Co., Ltd.)
* 2
Silicone graft acrylic resin: Cymac US-450 (Toa Gosei Co., Ltd.)
* 3
Aqueous solution of high molecular weight block copolymer having groups with affinity for pigment: DISPERBYK-190 (Bic Chemie Japan KK)
※Four
Polyamidoamine salt: TW-124 (Ito Oil Co., Ltd.)
※Five
Perchlorate: KS-555 (Kao Corporation)
* 6
A mixture of mineral oil, polyether, hydrophobic silica, water, etc .: SN deformer 777 (San Nopco)
* 7
Hydrophilic group-containing aliphatic block polyisocyanate: Bihijoule 2310 (Suika Bayer Urethane Co., Ltd.)
* 8
Hydrophilic group-containing aliphatic block polyisocyanate: DP9C / 214 (GSI Creos Co., Ltd.)
* 9
Hydrophilic polyisocyanates containing hydrophilic groups: Bihijoule 3100 (Sumika Bayer Urethane Co., Ltd.)
※Ten
Spherical fine particles of crosslinked polymethyl methacrylate: MBX-8 (Sekisui Chemical Co., Ltd.)
* 11
Aqueous dispersion of black organic pigment: BONJET BLACK CW-1 (Oriento Chemical Co., Ltd.)
* 12
Aqueous dispersion of black organic pigment: BSYD-15007 (Oguni Color Co., Ltd.)
※13
purified water

  As the water-based resin, water-dispersed fluororesin: FE4400 (Asahi Glass Co., Ltd.) was used. To this water-based resin, silicone graft acrylic resin as additive: Cymac US-450 (Toa Gosei Co., Ltd.), aqueous solution of high molecular weight block copolymer having a group having affinity for pigment: DISPERBYK-190 (Bic Chemie Japan) ), Polyamidoamine salt: TW-124 (Ito Oil Co., Ltd.), perchlorate: KS-555 (Kao Corporation), mineral oil, polyether, hydrophobic silica, water, etc. Deformer 777 (San Nopco) was added.

  In Example 1, the cross-linking agent is hydrophilic group-containing aliphatic block polyisocyanate: Bihijoule 2310 (Suika Bayer Urethane Co., Ltd.), and in Example 2, hydrophilic group-containing aliphatic block polyisocyanate: DP9C / 214 ( GSI Creos Co., Ltd.) was used as a comparative example, and a hydrophilic group-containing aliphatic polyisocyanate: Bihijoule 3100 (Sumika Bayer Urethane Co., Ltd.) was used.

  In addition, the spherical particles of crosslinked polymethyl methacrylate: MBX-8 (Sekisui Kasei Kogyo Co., Ltd.) as the particles, and the aqueous dispersion of black organic pigment as the conductive agent: BONJET BLACK CW-1 (Oriento Chemical Co., Ltd.) ), And an aqueous dispersion of black organic pigment: BSYD-15007 (Mikuni Dye Co., Ltd.). Furthermore, purified water was used as the solvent.

  Each water-based paint of Table 1 was applied by dipping on the intermediate layer of the conductive roller, and then dried at 130 ° C. for 2 hours to form the outermost layer. This conductive roller has a shaft of hollow metal and an elastic layer made of a polyurethane foam mainly composed of an isocyanate component and a polyol component, and has a thickness of 1.2 mm. An intermediate layer is formed on the surface of the elastic layer. A water-based paint is applied by dipping and then dried at 105 ° C. for 1 hour. The water-based paint of the intermediate layer was a blend in which carbon was added as a conductive agent to a urethane resin. The thickness of the intermediate layer was 120 μm.

  With respect to the water-based paints in Table 1, the paint viscosity for paint stability evaluation, the thickness of the outermost layer, the presence or absence of surface cracks, and the contamination blocking property of the conductive roller obtained by coating and drying were investigated. Surface cracks were observed visually and with a microscope. Contamination blockiness was observed in a wet atmosphere at 50 ° C. and 95% humidity with the conductive roller in contact with the organic photoconductor for 14 days, followed by image formation using the organic photoconductor. An evaluation was made based on whether or not a trace appeared in the image, and a case where no contamination trace appeared was evaluated as a circle, and a case where it appeared was evaluated as a cross. These investigations were evaluated when the aqueous solvent was applied on the first day of formulation and when applied on the fourth day of formulation.

  Table 1 shows the results of these surveys. As can be seen from Table 1, Example 1 and Example 2 in which the water-based resin of the outermost layer contains a cross-linking agent of a blocked isocyanate compound did not cause surface cracks and were excellent in contamination blocking properties. In contrast, the comparative example in which the crosslinking agent was a non-blocking type isocyanate compound had no cracks or contamination on the first day of blending, but cracked or contaminated on the fourth day of blending. This is probably because the isocyanate was deactivated on the 4th day of blending and the crosslinking reaction did not proceed.

11 shaft, 12 elastic layer, 13 surface layer, 13a intermediate layer, 13b outermost layer

Claims (4)

A shaft,
An elastic layer formed on the outer periphery of the shaft;
A surface layer formed on the outer peripheral surface of the elastic layer,
It said surface layer, water-based paints and coating consists of a plurality of layers including a dried layer, and outermost layer, applying an aqueous coating material containing a crosslinking agent of the blocked isocyanate compound, Ri Na and dried, and,
The outermost layer of the water-based paint, acrylic, urethane, acrylic urethane, one or more conductive roller resin der Rukoto characterized selected from fluorine-based. The conductive roller according to claim 1, wherein the outermost layer has a thickness of 1 to 30 μm. The conductive roller according to claim 1, wherein the blocked isocyanate compound is a hydrophilic group-containing aliphatic blocked polyisocyanate. The conductive roller according to claim 1, wherein a ratio of the blocked isocyanate compound to the water-based paint is in a range of 0.2 to 1.5 equivalents.

Images