JP2001304245A - Foam body roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foam body roller fluctuating no volume specific resistance in fluctuating the environment, reducing the initial adhesion of the roller surface, and providing a high definition picture in being used for a transfer roller, and to provide an image formation device equipped with the foam body roller. SOLUTION: This form body roller is formed with a solid layer on a skin surface layer of the foam body roller having an elastic layer comprising a foam body layer and the skin layer. In this foam body roller and the image formation device equipped with the foam body roller, the volume specific resistance of the solid layer and the volume specific resistance of the elastic layer have a relation of the volume specific resistance of the solid layer/the volume specific resistance of the elastic layer <=1.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foam roller suitably used in an electrophotographic apparatus such as a copying machine, a facsimile, and a printer, and an image forming apparatus equipped with the foam roller.

[0002]

2. Description of the Related Art In recent years, with the progress of electrophotographic technology, image forming apparatuses such as dry electrophotographic apparatuses have been used for charging, developing,
Attention has been paid to polymer elastic members as members used for transfer, toner supply, cleaning, and the like, and elastic rollers and toners such as a charging roller, a developing roller, a transfer roller, a toner supply roller, and a cleaning roller. It is used in the form of an elastic blade such as a layer regulating blade or a cleaning blade. When the polymer elastic member is used for transfer, toner supply, cleaning, and the like, which are particularly required to have low hardness, it is preferable to apply a polymer elastic foam. Among the foam rollers made of polymer elastic foam, in particular, as the transfer roller, conventionally, a roller having only a foam layer, a roller having a foam layer and a skin layer, a roller having a foam layer and a solid layer Commonly used. However, when controlling the volume resistivity in a transfer roller having a roller surface polished and having only a foam layer, it is difficult to adjust the control because the control must be performed by controlling only the foam layer. There's a problem. In addition, there is a problem that the volume specific resistance greatly varies depending on the environment. A transfer roller having a foam layer and a skin layer or a solid layer may have a volume resistivity of the skin layer or the solid layer greater than a volume resistivity of the foam layer, or a transfer of the skin layer or the solid layer and the foam layer. In many cases, attention is not paid to the distribution of volume specific resistance between them, and there is a large change in resistance with respect to a change in applied voltage.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and does not fluctuate in volume resistivity even if the environment fluctuates, reduces the tackiness of the roller surface, and changes the applied voltage. It is an object of the present invention to provide a foam roller capable of obtaining a high-quality image when used as a transfer roller and having a small resistance variation with respect to the image forming apparatus, and an image forming apparatus equipped with the foam roller.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and found that the volume resistivity of the solid layer and the volume of the elastic layer composed of the foam layer and the skin layer were determined. Foam roller with specific resistance and specific resistance,
It has been found that it is suitable for the above purpose. The present invention has been completed based on such findings. That is, the present invention is a foam roller in which a solid layer is formed on a skin layer surface of a foam roller having an elastic layer composed of a foam layer and a skin layer, and the volume resistivity of the solid layer and the elastic layer Provided is a foam roller, wherein the volume resistivity is in a relationship of volume resistivity of the solid layer / volume resistivity of the elastic layer ≦ 1.0, and an image forming apparatus equipped with the foam roller. Things.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, polyurethane foam, silicone rubber foam,
Ethylene propylene rubber foam, nitrile butadiene rubber foam, urethane rubber foam, and the like.
Of these, polyurethane foam is preferred. As the polyisocyanate constituting the polyurethane raw material, an aromatic isocyanate or a derivative thereof, an aliphatic isocyanate or a derivative thereof, and an alicyclic isocyanate or a derivative thereof are used. Of these, aromatic isocyanates or derivatives thereof are preferable, and tolylene diisocyanate or derivatives thereof, diphenylmethane diisocyanate or derivatives thereof are particularly preferably used. As tolylene diisocyanate or its derivative, crude tolylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-
Tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, a urea-modified product, a buret-modified product, a carbodiimide-modified product thereof, and the like are used. As diphenylmethane diisocyanate or its derivative, for example, diphenylmethane diisocyanate or its derivative obtained by phosgenating diaminodiphenylmethane or its derivative is used. Examples of the derivative of diaminodiphenylmethane include polynuclear substances, such as pure diphenylmethane diisocyanate obtained from diaminodiphenylmethane, and polymeric diphenylmethane diisocyanate obtained from a polynuclear substance of diaminodiphenylmethane. As for the number of functional groups of polymeric diphenylmethane diisocyanate, a mixture of pure diphenylmethane diisocyanate and polymeric diphenylmethane diisocyanate having various functional groups is used, and the average number of functional groups is preferably 2.05 to 4.00, more preferably 2. Those having 50 to 3.50 are used. Derivatives obtained by modifying these diphenylmethane diisocyanates or derivatives thereof, for example, urethane modified products modified with polyols and the like, dimers formed by uretidione formation,
Modified isocyanurate, modified carbodiimide / uretonimine, modified allohanate, modified urea, modified buret, and the like can also be used. In addition, several kinds of diphenylmethane diisocyanates and derivatives thereof can be used by blending.

[0006] Polyol components constituting polyurethane raw materials include polyether polyol obtained by addition polymerization of ethylene oxide and propylene oxide, polytetramethylene ether glycol, polyester polyol obtained by condensing an acid component and a glycol component, and caprolactone by ring-opening polymerization. Polyester polyol, polycarbonate diol and the like can be used. Polyether polyols obtained by addition polymerization of ethylene oxide and propylene oxide include, for example, water, propylene glycol, ethylene glycol, glycerin, trimethylolpropane, hexanetriol, triethanolamine, diglycerin, pentaerythritol, ethylenediamine, methylglucode, Starting materials are aromatic diamines, sorbitol, sucrose, phosphoric acid, and the like, and examples of addition polymerization of ethylene oxide and propylene oxide include water, propylene glycol, ethylene glycol, glycerin, trimethylolpropane, and the like. Those using hexanetriol as a starting material are preferred. Regarding the ratio of ethylene oxide to propylene oxide and the microstructure to be added, the ratio of ethylene oxide is preferably from 2 to 95% by weight, more preferably from 5 to 90% by weight. Those having ethylene oxide added to the terminal are preferably used. Also, the arrangement of ethylene oxide and propylene oxide in the molecular chain is preferably random. The molecular weight of the polyether polyol is bifunctional when water, propylene glycol or ethylene glycol is used as a starting material, and is preferably in the range of 300 to 6000 in weight average molecular weight, particularly preferably in the range of 400 to 3000. . When glycerin, trimethylolpropane, or hexanetriol is used as a starting material, it is trifunctional and preferably has a weight average molecular weight in the range of 900 to 9000, particularly preferably 1500 to 6000. In addition, a bifunctional polyol and a trifunctional polyol can be appropriately blended and used.

The polytetramethylene ether glycol is obtained, for example, by cationic polymerization of tetrahydrofuran, and those having a weight average molecular weight of 400 to 4000, particularly preferably 650 to 3000 are preferably used. It is also preferable to blend polytetramethylene ether glycols having different molecular weights. further,
Polytetramethylene ether glycol obtained by copolymerizing an alkylene oxide such as ethylene oxide or propylene oxide can also be used. It is also preferable to use a polytetramethylene ether glycol and a polyether polyol obtained by addition polymerization of ethylene oxide and propylene oxide,
In this case, polytetramethylene ether glycol,
The ratio of polyether polyol obtained by addition polymerization of ethylene oxide and propylene oxide is 9 by weight.
It is preferably used so as to be in the range of 5: 5 to 20:80, particularly preferably in the range of 90:10 to 50:50. Further, together with the polyol component, a polymer polyol obtained by modifying the polyol with acrylonitrile, a polyol obtained by adding melamine to the polyol, a diol such as butanediol, a polyol such as trimethylolpropane, or a derivative thereof can be used in combination. The polyol may be prepolymerized with a polyisocyanate in advance. The method is as follows. The polyol and the polyisocyanate are put in an appropriate container and sufficiently stirred, and 30 to 90 ° C., more preferably 40 to 90 ° C.
~ 70 ° C for 6-240 hours, more preferably 24-7
There is a method of keeping the temperature for 2 hours.

Examples of the catalyst used for the curing reaction of the polyurethane raw material include monoamines such as triethylamine and dimethylcyclohexylamine, diamines such as tetramethylethylenediamine, tetramethylpropanediamine and tetramethylhexanediamine, pentamethyldiethylenetriamine and pentamethyldipropylene. Triamines such as triamine and tetramethylguanidine; cyclic amines such as triethylenediamine, dimethylpiperazine, methylethylpiperazine, methylmorpholine, dimethylaminoethylmorpholine and dimethylimidazole; dimethylaminoethanol, dimethylaminoethoxyethanol and trimethylaminoethylethanolamine , Methylhydroxyethylpiperazine, hydroxyethylmorpholine and other alcohols Min, bis (dimethylaminoethyl) ether, ethylene glycol bis (dimethyl)
Ether amines such as aminopropyl ether, stannas octoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin marker, dibutyltin thiocarboxylate, dibutyltin dimaleate, dioctyltin marker, dioctyltin thiocarboxylate, phenylmercurypropion And organometallic compounds such as lead octenoate. These catalysts may be used alone or in combination of two or more.

When the foam roller of the present invention is a conductive roller, a conductive material is added to the foam material. The conductive material includes an ionic conductive material and an electronic conductive material. The conductive material added to the foam raw material is not limited, but it is preferable to use an ionic conductive material. The conductive material to be added to the solid layer described later is not limited, but it is preferable to use an electronic conductive material. Examples of ion conductive materials include tetraethylammonium, tetrabutylammonium,
Perchlorates, chlorates, hydrochlorides of ammonium such as dodecyltrimethylammonium such as lauryltrimethylammonium, hexadecyltrimethylammonium, octadecyltrimethylammonium such as stearyltrimethylammonium, benzyltrimethylammonium, and modified aliphatic dimethylethylammonium; Organic ion conductive materials such as bromate, iodate, borofluoride, sulfate, alkyl sulfate, carboxylate and sulfonate; alkali metals or alkaline earths such as lithium, sodium, calcium and magnesium Inorganic ion conductive materials such as metal perchlorates, chlorates, hydrochlorides, bromates, iodates, borofluorides, trifluoromethyl sulfates, and sulfonates are exemplified. Examples of the electronic conductive material include conductive carbon blacks such as Ketjen black and acetylene black; SAF, ISAF, HA
Carbon black for rubber such as F, FEF, GPF, SRF, FT, MT; carbon black for ink such as carbon oxide black, pyrolytic carbon black, graphite; conductive metal oxide such as tin oxide, titanium oxide, zinc oxide Metals such as nickel and copper; conductive whiskers such as carbon whiskers, graphite whiskers, titanium carbide whiskers, conductive potassium titanate whiskers, conductive barium titanate whiskers, conductive titanium oxide whiskers, and conductive zinc oxide whiskers; No. By adding the conductive material, the volume resistivity of the foam roller of the present invention can be adjusted. When the foam roller according to the present invention is used as a transfer roller, the volume resistivity is preferably in the range of 10 ⁵ to 10 ¹⁰ Ω · cm from the viewpoint of obtaining a good image.

[0010] In addition to the above-mentioned conductive materials, fillers such as inorganic carbonates, foam stabilizers such as silicone foam stabilizers and various surfactants, and antioxidants such as phenol and phenylamine are used for foam materials such as polyurethane materials. Agents, low friction agents, charge control agents and the like can be added. As the silicone foam stabilizer, a dimethylpolysiloxane-polyoxyalkylene copolymer or the like is suitably used, and those comprising a dimethylpolysiloxane portion having a molecular weight of 350 to 15,000 and a polyoxyalkylene portion having a molecular weight of 200 to 4000 are particularly preferable.
The molecular structure of the polyoxyalkylene moiety is preferably an ethylene oxide addition polymer or a co-addition polymer of ethylene oxide and propylene oxide, and it is also preferable that the molecular terminal is ethylene oxide. Examples of the surfactant include cationic surfactants, anionic surfactants, ionic surfactants such as amphoteric surfactants, and nonionic surfactants such as various polyethers and various polyesters. The amount of the silicone foam stabilizer and various surfactants is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the foam raw material.

As a method for producing a foam, there are a mechanical floss method, a water foaming method, a foaming agent floss method, and the like.
In the present invention, it is preferable to use a mechanical floss method. To manufacture a foam roller by mecarcal floss, a metal shaft or the like is placed in advance, and a foam material that has been foamed by mechanical stirring is injected into a preheated inner cylindrical mold, and reaction hardening is performed. Alternatively, the raw material of the foam may be injected into a mold, and may be reactively hardened while mixing an inert gas and adding mechanical stirring. Here, the inert gas used in the mechanical floss method is
For example, in the case of a polyurethane reaction, any gas that is inert in the polyurethane reaction may be used, such as helium, argon,
In addition to inert gases in a narrow sense, such as xenon, radon, and krypton, gases that do not react with polyisocyanates, such as nitrogen, carbon dioxide, and dry air, may be mentioned. The foam roller obtained by such a method is a foam roller in which a skin layer is formed in a portion in contact with a mold, and the average foam cell diameter of the foam roller is 50 to 400 μm. When using a foam roller of the present invention as a transfer roller, in terms of the charging efficiency and transfer efficiency, the density of the foam is preferably 0.6 g / cm ³ or less, more preferably 0.4 to 0.5 g / cm ³ It is. The Asker C hardness of the foam is preferably 40 ° or less, more preferably 10 to 30 °. The average foam cell diameter is preferably 400 μm or less, more preferably 1 μm or less.
It is 00 to 300 μm. The thickness of the skin layer is preferably from 10 μm to 1 mm, more preferably from 50 to 100 μm, from the viewpoint of maintaining an appropriate cell diameter. The thickness of the skin layer can be adjusted by a molding temperature or a chemical reaction rate (curing rate). This skin layer plays a role in the fluctuation of the volume resistivity due to the environment in the foam roller of the present invention.

[0012] The foam roller of the present invention has a solid layer formed on the surface of a skin layer. The resin forming the solid layer is not particularly limited, but a fluorine-based resin is preferable from the viewpoints of toner releasability and stain resistance. Examples of fluororesins include fluoroolefin-modified copolymers, PVdF (polyvinylidene fluoride), EC
TFE (ethylene / chlorotrifluoroethylene copolymer) and the like. As a method of forming the solid layer, a method of coating as a coating film, a method of covering an extruded seamless tube, or the like can be used. The thickness of the solid layer is preferably from 5 to 200 μm, more preferably from 10 to 100 μm, from the viewpoint of exhibiting electrical characteristics (voltage adjustment).

The foamed roller of the present invention is such that the volume resistivity of the solid layer and the volume resistivity of the elastic layer have a relationship of volume resistivity of the solid layer / volume resistivity of the elastic layer ≦ 1.0. However, it is preferable that the volume resistivity of the solid layer / the volume resistivity of the elastic layer ≦ 0.8. If the volume resistivity of the solid layer / the volume resistivity of the elastic layer exceeds 1.0, that is, if the volume resistivity of the solid layer is greater than the volume resistivity of the elastic layer, the shared voltage applied to the solid layer will increase. Thus, the resistance of the solid layer changes with respect to the change in the applied voltage, and the transfer performance deteriorates. The foam roller of the present invention is suitably used as a transfer roller mounted on an image forming apparatus such as a plain paper copying machine, a plain paper facsimile machine, a laser beam printer, a color laser beam printer, and a toner jet printer.

[0014]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 is a mixture of diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, and glycol-modified diphenylmethane diisocyanate,
24.6 parts by weight of an isocyanate component having an isocyanate content of 26.2% by weight, and 60 parts by weight of a polyether polyol having a weight average molecular weight of 5,000 obtained by addition polymerization of ethylene oxide and propylene oxide with glycerin as a starting material, and 60 parts by weight of a molecular weight of 1,000 40 parts by weight of polytetramethylene ether glycol, hydroxyl value of 56 mg KO
H / g of 4 parts by weight of a reactive silicone foam stabilizer, 2.5 parts by weight of a black pigment, 0.5 parts by weight of ethyl sulfate-modified aliphatic dimethylethylammonium as an electrolyte and 0.01 parts by weight of dibutyltin dilaurate as a catalyst The resulting polyol components were mixed to prepare a polyurethane raw material. The polyurethane raw material was mechanically stirred with a mixer, mixed with dry air, and foamed. This foamed polyurethane raw material,
It was poured into a metal cylindrical split mold. Inside this mold, 6.0m outer diameter made of zinc-plated sulfur free-cutting steel
An adhesive is applied to a shaft having a length of 240 mm and a length of 240 mm. Next, the mold into which the foamed polyurethane material was cast was left in a hot-air oven adjusted to 90 ° C. for 4 hours to cure the foamed polyurethane material. The cured polyurethane foam was removed from the mold to obtain a roller having an outer diameter of 12 mm and a total length of the foam portion of 210 mm. Polyurethane foam skin layer thickness is 100
μm. 100 parts by weight of the fluoroolefin-modified copolymer was carbon black (Mitsubishi Kasei Corporation, # 2
400B) A mixture to which 15 parts by weight was added was applied to the surface of the skin layer by a dipping coating method to form a solid layer. The average foam cell diameter of polyurethane foam is 300μ
m, density 0.50 g / cm ³ , Asker C hardness 40
°, the volume resistivity was 1 × 10 ⁷ Ω · cm. The solid layer has a thickness of 50 μm and a volume resistivity of 5 ×
It was 10 ⁶ Ω · cm. The thickness of the skin layer, the diameter of the foamed cell, and the thickness of the solid layer were measured using a micro video camera manufactured by Keyence Corporation at a magnification of 400 times, and the cell diameter of the image was measured. The specific volume resistance of the polyurethane foam roller was determined by curing a foamed polyurethane raw material used in the production of the roller with a flat mold under the same conditions as above to produce a polyurethane foam sheet having a thickness of 5 mm. Was measured using a resistance measuring instrument. In addition, the volume specific resistance of the solid layer is obtained by applying the coating liquid used for forming the solid layer to a copper plate, drying the same under the same conditions as the formation of the solid layer, and measuring the resistance between the copper plate and a measurement electrode. Determined by The obtained transfer roller was mounted on an electrophotographic image forming apparatus, and the transfer performance of the image was evaluated in a low-temperature and low-humidity (15 ° C., 10% RH) environment. No image transfer performance was confirmed. The transfer image missing refers to a phenomenon in which only an outline of an image to be transferred is transferred, and the inside of the image is not transferred.

Example 2 In Example 1, the amount of the ethyl sulphate-modified aliphatic dimethylethylammonium was 0.8 parts by weight, and the solid layer was 100 parts by weight of PVdF polymer and carbon black (Mitsubishi Kasei Co., # 2400B). A transfer roller was manufactured in the same manner as in Example 1 except that the transfer roller was formed using a mixture to which 15 parts by weight was added. The volume resistivity of the polyurethane foam and the volume resistivity of the solid layer are both 5 × 10 ⁶ Ω · cm.
Met. This roller was mounted on an electrophotographic image forming apparatus, and the same evaluation as in Example 1 was carried out. As a result, it was confirmed that the transferred image had no missing or uneven image and the image transfer performance was good. Comparative Example 1 In the same manner as in Example 1, except that the solid layer was formed of a mixture of 100 parts by weight of a fluoroolefin-modified copolymer and 10 parts by weight of carbon black (manufactured by Mitsubishi Kasei Corporation, # 2400B). Thus, a transfer roller was manufactured. The volume resistivity of polyurethane foam is 1 × 1
0 ⁷ Ω · cm, volume resistivity of solid layer is 1 × 10 ⁸
Ω · cm. This roller was mounted on an electrophotographic image forming apparatus, and the same evaluation as in Example 1 was carried out. As a result, transfer image omission was not observed, but image unevenness was observed. Comparative Example 2 In Example 1, the addition amount of ethyl sulfate-modified aliphatic dimethylethylammonium was 1.0 part by weight, and the solid layer was coated with 100 parts by weight of a fluoroolefin-modified copolymer in carbon black (Mitsubishi Kasei Co., # 2400B). ) 1
A transfer roller was manufactured in the same manner as in Example 1 except that the transfer roller was formed with a mixture to which 0 parts by weight was added. The volume resistivity of the polyurethane foam was 1 × 10 ⁶ Ω · cm, and the volume resistivity of the solid layer was 1 × 10 ⁸ Ω · cm. The roller was mounted on an electrophotographic image forming apparatus, and the same evaluation as in Example 1 was carried out.

[0016]

The foam roller of the present invention is suitable as a transfer roller because the volume resistivity does not change even if the environment changes, and the tackiness of the roller surface is reduced.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) B32B 27/30 B32B 27/30 D 27/40 27/40 G03G 15/16 103 G03G 15/16 103 F term (Ref.)

Claims (8)

[Claims] 1. A foam roller in which a solid layer is formed on the surface of a skin layer of a foam roller having an elastic layer composed of a foam layer and a skin layer, wherein the solid layer has a volume resistivity and a volume of the elastic layer. A foam roller, wherein the specific resistance has a relationship of volume resistivity of the solid layer / volume resistivity of the elastic layer ≦ 1.0. 2. The foam roller according to claim 1, wherein the skin layer has a thickness of 10 μm to 1 mm, and the solid layer has a thickness of 5 to 200 μm. 3. The solid layer has a volume resistivity of 1 × 10 ⁵ to 1 × at room temperature and normal humidity (23 ° C., 50% RH).
The foamed roller according to claim 1 or 2, wherein the foamed roller has a resistance of 10 ⁹ Ω · cm. 4. The foaming roller according to claim 1, wherein the solid layer is made of a fluororesin. 5. The foam roller according to claim 1, wherein the average foam cell diameter is 50 to 50.
The foamed roller according to any one of claims 1 to 4, which has a thickness of 400 µm. 6. The foam roller according to claim 1, wherein the foam roller is made of polyurethane foam. 7. The foam roller according to claim 1, wherein the foam roller is a transfer roller. 8. An image forming apparatus comprising the foam roller according to claim 1.