JP2022089808A - Conductive urethane foam, manufacturing method therefor, and conductive roller - Google Patents

Abstract

To provide a conductive urethane foam which requires less burden on a conductive agent impregnation process and offers a stable chargeability imparting effect, and to provide a conductive roller.SOLUTION: A conductive urethane foam of the present invention has an impregnation solution, containing a conductive agent and a binder resin, impregnated in a surface layer of a urethane foam base material, where the binder resin contains at least one selected from an acrylic resin and silicone resin, and the impregnation solution contains a low molecular weight siloxane compound.SELECTED DRAWING: Figure 2

Description

The present invention relates to a conductive urethane foam, a method for manufacturing a conductive urethane foam, and a conductive roller.

Generally, as shown in FIG. 1, an image forming body 11 such as a photoconductor holding an electrostatic latent image and this image forming body are used in a developing unit of an electrophotographic image forming apparatus such as a copier or a printer. A developing roller 12 for making an electrostatic latent image into a visible image by abutting on 11 and adhering a toner 20 carried on the surface, and a toner supply roller 13 for supplying toner to the developing roller 12 are provided. Image formation is performed by a series of processes of transporting the toner 15 from the toner accommodating portion 14 to the image forming body 11 via the toner supply roller 13 and the developing roller 12.

Of these, the toner supply roller 13 has an adhesive layer on the outer periphery of the shaft from the viewpoint of not damaging the developing roller 12 in contact with the roller and increasing the contact area of the rollers to ensure grip. Examples thereof include a configuration in which a conductive elastic body such as urethane foam is formed. The functions required of the toner supply roller 13 include toner transportability, toner chargeability, and the like, and various measures have been taken to satisfy these functions.

For example, in Patent Documents 1 to 3, the electric resistance of the toner supply roller is lowered by impregnating the polyurethane foam constituting the toner supply roller with a treatment liquid containing a conductive agent such as conductive carbon black, and the toner is charged. A technique that makes it possible to reduce the amount (Q / M) and increase the toner transfer amount (M / A) is disclosed.
Further, in Patent Document 4, for the purpose of enhancing the effect of imparting stable chargeability and obtaining a good image (improving the stability of the roller), the polyurethane having a foam structure supported through the rotating shaft is conductive. A conductive elastic roller impregnated with a liquid silicone rubber is disclosed.

Japanese Unexamined Patent Publication No. 57-115433 Japanese Unexamined Patent Publication No. 2002-319315 Japanese Unexamined Patent Publication No. 2003-215905 Japanese Unexamined Patent Publication No. 2003-262997

The techniques disclosed in Patent Documents 1 to 4 have made it possible to enhance the effect of imparting chargeability to some extent. However, in each of the techniques of Patent Documents 1 to 4, there is a problem that the work for impregnating the urethane foam with the conductive material needs to be performed a plurality of times (6 times or more), which increases the burden at the time of manufacturing. ..
Further, in the techniques of Patent Documents 1 to 4, the work of impregnating the urethane foam with the conductive agent takes time and labor, so that the resistance may vary depending on the part of the obtained urethane foam, and the chargeability is sufficient. There was also the problem that the granting effect could not be obtained.

Therefore, an object of the present invention is to provide a method for producing a conductive urethane foam and a conductive urethane foam, which requires less burden for the impregnation treatment of the conductive agent and realizes a stable chargeability-imparting effect. Another object of the present invention is to provide a toner supply roller having a high chargeability-imparting effect and excellent stability.

The present inventor has diligently studied a conductive urethane foam in which the surface layer of the urethane foam base material is impregnated with an impregnating liquid containing a conductive agent and a binder resin in order to solve the above problems. As a result, the binder resin is composed of at least one selected from acrylic resin and silicone resin, and the impregnating liquid further contains a siloxane compound having a low molecular weight, whereby the urethane foam base material of the impregnating liquid is used. Since the permeation rate into the silicone can be increased, the burden required for the impregnation treatment can be significantly reduced, and the impregnation treatment can be performed more efficiently and stably, the obtained conductive urethane foam has a variation in resistance. It was found that a stable chargeability-imparting effect can be realized.

That is, the conductive urethane foam of the present invention is a conductive urethane foam in which the surface layer of the urethane foam base material is impregnated with an impregnating liquid containing a conductive agent and a binder resin, and the binder resin is an acrylic resin and a silicone resin. It contains at least one selected from the above, and the impregnating solution is characterized by further containing a low molecular weight siloxane compound.
By providing the above configuration, the burden required for the impregnation treatment of the conductive agent is small, and a stable chargeability imparting effect can be realized.

Further, in the conductive urethane foam of the present invention, the molecular weight of the siloxane compound is preferably 500 to 1,000. This is because the impregnation treatment can be carried out more efficiently and stably while preventing elution from the urethane foam base material.

Further, in the conductive urethane foam of the present invention, the content of the siloxane compound in the impregnating liquid is preferably 2% by mass or more. This is because the impregnation treatment can be performed more efficiently and stably.

Furthermore, for the conductive urethane foam of the present invention, it is preferable that the binder resin contains at least an acrylic resin. This is because the impregnation treatment can be efficiently performed and the strength of the surface layer can be increased.

The method for producing a conductive urethane foam of the present invention is a method for producing a conductive urethane foam, which comprises a step of impregnating the surface layer of a urethane foam base material with an impregnating liquid containing a conductive agent and a binder resin a plurality of times. The binder resin contains at least one selected from an acrylic resin and a silicone resin, and the impregnating liquid further contains a siloxane compound having a lower molecular weight.
By providing the above configuration, a high charging effect and excellent stability can be realized.

Further, in the method for producing a conductive urethane foam of the present invention, it is preferable that the number of times the urethane foam base material is impregnated with the impregnating liquid is 3 times or less. This is because the impregnation treatment can be performed more efficiently.

Further, in the method for producing the conductive urethane foam of the present invention, the molecular weight of the siloxane compound is preferably 500 to 1,000. This is because the impregnation treatment can be carried out more efficiently and stably while preventing elution from the urethane foam base material.

The conductive roller of the present invention is characterized in that the above-mentioned electric urethane foam of the present invention is used.
By providing the above configuration, it is possible to realize a stable chargeability imparting effect without variation in resistance.

Further, with respect to the conductive roller of the present invention, it is preferable that the conductive urethane foam constitutes the outermost layer of the conductive roller. This is because a stable chargeability imparting effect can be realized without providing an outermost layer such as a protective layer.

According to the present invention, it is possible to provide a method for producing a conductive urethane foam and a method for producing a conductive urethane foam, in which the burden required for the impregnation treatment of the conductive agent is small and a stable chargeability imparting effect is realized. Further, according to the present invention, it is possible to provide a toner supply roller having a high chargeability-imparting effect and excellent stability.

Further, in the method for producing a conductive urethane foam of the present invention, it is preferable that the number of times the urethane foam base material is impregnated with the impregnating liquid is 3 times or less. This is because the impregnation treatment can be performed more efficiently.

It is a partial cross-sectional view schematically showing an example of an image forming apparatus. It is sectional drawing which shows the embodiment of the toner supply roller of this invention schematically. It is a graph which showed the resistance value of the conductive urethane foam obtained in an Example and a comparative example, and the variation thereof.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings as necessary.
<Conductive urethane foam>
The conductive urethane foam of the present invention is obtained by impregnating the surface layer of a urethane foam base material with an impregnating liquid containing a conductive agent and a binder resin.
By impregnating the surface layer of the urethane foam base material with an impregnating liquid containing a conductive agent and a binder resin, the chargeability-imparting effect can be exhibited and a good image can be obtained.

(Urethane foam base material)
The urethane foam base material constituting the conductive urethane foam of the present invention is not particularly limited, and known urethane foam can be appropriately used depending on the intended use and purpose.

Regarding the urethane foam base material, for example, a compound having two or more active hydrogens and a compound having two or more isocyanate groups are stirred and mixed with additives such as a catalyst, a foaming agent, and a foam stabilizer to foam. It can be manufactured by curing. For example, a polyether polyol containing a mixture of two types of single diols having an average molecular weight difference of 800 to 3600 in a total amount of 50% by mass or more with respect to the polyol component, isocyanate, water, and a catalyst. And a foaming agent are mixed, foamed, and left to stand to produce the product.

Here, the term "single diol" is used to collectively refer to one type of diol or a group of two or more types of diols having a difference in average molecular weight of 400 or less. Further, the "average molecular weight difference" is used to represent the difference in the average molecular weight of each of the target diols, and particularly when there are many types of combinations, to represent the maximum difference.

As the polyol component used for producing the prepolymer, for example, a polyether polyol obtained by addition-polymerizing ethylene oxide and propylene oxide, a polytetramethylene ether glycol, a polyester polyol obtained by condensing an acid component and a glycol component, and a caprolactone are opened. A ring-polymerized polyester polyol, a polycarbonate diol, or the like can be used.

In the present invention, the polyether polyol used when producing the urethane foam base material is, for example, (A) a type of polyether polyol in which only propylene oxide is added to (A) diethylene glycol, and (B) diethylene glycol and propylene. Examples thereof include a type of polyether polyol in which oxide and ethylene oxide are blocked or randomly added, and (C) a type of polyether polyol obtained by grafting, for example, acrylic nitrile or styrene to the above (A) or (B). .. Among them, in order to exert more effect, the (A) type polyether polyol is preferable.

Examples of the initiator used for producing the polyether polyol include polyhydric alcohols, polyhydric phenols, mono or polyamines, and others, but polyhydric alcohols and polyhydric phenols are preferable, and polyhydric phenols are more preferable. Is a polyhydric alcohol, and includes, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, and the like, of which diethylene glycol is particularly preferable.

Further, the polyether polyol component may contain a polyol component other than the diol. As such a polyol component, there are usually two types of trifunctional materials used for producing a urethane foam base material, for example, a glycerin base to which an alkylene oxide such as propylene oxide is added, and propylene oxide and ethylene oxide. Examples thereof include those in which the above alkylene oxide is added randomly or in a block, and examples of the polyfunctional one include a polyether polyol in which the same as described above is added to a saccharose base.

Examples of the polyether polyol obtained by addition-polymerizing ethylene oxide and propylene oxide include water, propylene glycol, ethylene glycol, glycerin, trimethylolpropane, hexanetriol, triethanolamine, diglycerin, pentaerythritol, ethylenediamine, and methylglucoside. Examples thereof include those obtained by addition-polymerizing ethylene oxide and propylene oxide with aromatic diamine, sorbitol, sucrose, phosphoric acid and the like as starting materials, and in particular, water, propylene glycol, ethylene glycol, glycerin and trimethyl propane. , Hexatriol as a starting material is preferable. Regarding the ratio of ethylene oxide to propylene oxide and the microstructure to be added, the ratio of ethylene oxide is preferably 2 to 95% by mass, more preferably 5 to 90% by mass, and those having ethylene oxide added to the ends are preferable. Further, 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 the weight average molecular weight is preferably in the range of 300 to 6000, preferably in the range of 3000 to 5000. Is more preferable. When glycerin, trimethylolpropane, or hexanetriol is used as a starting material, the starting material is trifunctional, and the weight average molecular weight is preferably in the range of 900 to 9000, more preferably in the range of 4000 to 8000. Further, a bifunctional polyol and a trifunctional polyol can be appropriately blended and used.

Further, the polytetramethylene ether glycol can be obtained, for example, by cationic polymerization of tetrahydrofuran, and those having a weight average molecular weight in the range of 400 to 4000, particularly in the range of 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.

Further, it is also preferable to use a blend of polytetramethylene ether glycol and a polyether polyol obtained by addition-polymerizing ethylene oxide and propylene oxide. In this case, it is preferable to use these blend ratios in the range of 95: 5 to 20:80 by mass ratio, particularly in the range of 90:10 to 50:50.

Further, together with the above-mentioned polyol component, a polymer polyol obtained by modifying a polyol with acrylonitrile, a polyol obtained by adding melamine to a polyol, diols such as butanediol, polyols such as trimethylolpropane, and derivatives thereof can also be used in combination.

As the polyisocyanate component, aromatic isocyanates or derivatives thereof, aliphatic isocyanates or derivatives thereof, alicyclic isocyanates or derivatives thereof are used. Among these, aromatic isocyanates or derivatives thereof are preferable, and in particular, toluene diisocyanate (TDI) or its derivatives, diphenylmethane diisocyanate (MDI) or its derivatives, polymethylene polyphenyl polyisocyanate or its derivatives are preferably used, and are used alone or as a derivative thereof. Used as a mixture.

Examples of the tolylene diisocyanate or a derivative thereof include crude tolylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate. Urea modified products, bullet modified products, carbodiimide modified products, urethane modified products modified with polyols, etc. are used. As the 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 a polynuclear body, and pure diphenylmethane diisocyanate obtained from diaminodiphenylmethane, polymeric diphenylmethane diisocyanate obtained from a polynuclear body of diaminodiphenylmethane, and the like can be used. As for the number of functional groups of the polypeptide diphenylmethane diisocyanate, a mixture of pure diphenylmethane diisocyanate and a polypeptide having various functional groups is usually used, and the average number of functional groups is preferably 2.05 to 4.00, more preferably 2. .50 to 3.50 are used. Further, a derivative obtained by modifying these diphenylmethane diisocyanate or a derivative thereof, for example, a urethane modified product modified with a polyol or the like, a dimer by uretidine formation, an isocyanurate modified product, a carbodiimide / uretonimine modified product, an alohanate modified product. , Urea modified product, Bullet modified product and the like can also be used. Further, several kinds of diphenylmethane diisocyanate and its derivatives can be blended and used.

As the method of prepolymerization, the polyol and isocyanate are placed in a suitable container and sufficiently stirred, and the temperature is 30 to 90 ° C., more preferably 40 to 70 ° C. for 6 to 240 hours, more preferably 24-72 hours. There is a method of keeping warm. In this case, the ratio of the amount of the polyol to the isocyanate is preferably adjusted so that the isocyanate content of the obtained prepolymer is 4 to 30% by mass, and more preferably 6 to 15% by mass. If the isocyanate content is less than 4% by mass, the stability of the prepolymer may be impaired and the prepolymer may be cured during storage, making it unusable. Further, when the isocyanate content exceeds 30% by mass, the content of the non-prepolymerized isocyanate increases, and this polyisocyanate undergoes a prepolymerization reaction with the polyol component used in the subsequent polyurethane curing reaction. Since it is cured by a reaction mechanism similar to that of the one-shot manufacturing method, the effect of using the prepolymer method is diminished.

The catalyst used for the curing reaction of the urethane foam base material is not particularly limited. For example, monoamines such as triethylamine and dimethylcyclohexylamine, diamines such as tetramethylethylenediamine, tetramethylpropanediamine and tetramethylhexanediamine, triamines such as pentamethyldiethylenetriamine, pentamethyldipropylenetriamine and tetramethylguanidine, and triethylenediamine. , Cyclic amines such as dimethylpiperazin, methylethylpiperazine, methylmorpholin, dimethylaminoethylmorpholin, dimethylimidazole, alcohols such as dimethylaminoethanol, dimethylaminoethoxyethanol, trimethylaminoethylethanolamine, methylhydroxyethylpiperazine, hydroxyethylmorpholin Amines, ether amines such as bis (dimethylaminoethyl) ether, ethylene glycol bis (dimethyl) aminopropyl ether, stanas octoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin mercaptide, dibutyltin thiocarboxylate, Examples thereof include organic metal compounds such as dibutyl tin dimaleate, dioctyl tin mercaptide, dioctyl tin thiocarboxylate, phenylmercury propionate, and lead octenoate. These catalysts may be used alone or in combination of two or more.

(Binder resin)
In the conductive urethane foam of the present invention, the impregnating liquid impregnated in the surface layer contains a binder resin, and the binder resin contains at least one selected from acrylic resin and silicone resin.
By using these resins as a binder resin, it is possible to efficiently impregnate the urethane foam base material after impregnating the urethane foam base material, and further change the hardness and impact resilience of the urethane foam. It can also be suppressed.

Here, the surface layer of the urethane foam base material is a layer formed by coating the skeleton of the urethane foam with an impregnating liquid containing a conductive agent and a binder resin. In the present invention, the thickness of the surface layer (layer impregnated with the impregnating liquid) is not particularly limited because a certain chargeability-imparting effect can be obtained if at least the surface is impregnated with the impregnating liquid.
Further, the impregnating liquid may be impregnated into at least a part of the surface layer of the urethane foam, but from the viewpoint of minimizing changes in the hardness and impact resilience of the urethane foam, the surface layer of the entire urethane foam base material. Is preferably impregnated with.

Here, the content of at least one selected from the acrylic resin and the silicone resin contained in the binder resin is not particularly limited as long as the surface layer of the urethane foam base material can be impregnated. For example, the content (total content) of at least one selected from the acrylic resin and the silicone resin can be 50% by mass or more, 70% by mass or more, or 100% by mass in the binder resin.
Further, the content of the binder resin in the impregnating liquid is not particularly limited. For example, it can be about 20 to 30% by mass.

Further, the content of at least one selected from the acrylic resin and the silicone resin in the conductive urethane foam of the present invention is 0.3 to 20% by mass with respect to 100 parts by mass of the base material of the urethane foam. It is preferably present, and more preferably 5 to 10% by mass. This is because changes in the hardness and repulsive elasticity of the urethane foam can be further suppressed, and when the content of the silicone resin is less than 0.3 parts by mass with respect to 100 parts by mass of the base material of the urethane foam, carbon is used. It may not adhere to the urethane foam and may fall off, and if it exceeds 20% by mass, the physical characteristics of the conductive urethane foam may change, and changes in hardness and impact resilience may not be sufficiently suppressed.

Further, the binder resin preferably contains at least an acrylic resin. This is because the impregnation treatment can be efficiently performed and the strength of the surface layer can be increased.
Here, the acrylic resin is not particularly limited as long as it is a polymer of acrylic acid ester or methacrylic acid ester, but it is preferable to use an acrylonitrile / alkyl acrylate copolymer. Furthermore, as the acrylic resin, a commercially available acrylic resin can be used, one type can be used alone, or a plurality of types can be mixed and used.

Further, the type of the silicone resin contained in the binder resin is not particularly limited as long as it is a polymer compound having a main skeleton due to a siloxane bond, and the silicone resin is appropriately selected and used according to the purpose and application. be able to. For example, from the viewpoint of improving processability and adhesion for impregnating the urethane foam base material with the silicone resin, the silicone resin is a silicone resin composed of a main agent of a liquid silicone gel and a curing agent. Is preferable. Examples of such a silicone resin include an addition reaction type liquid silicone resin, a heat vulcanization type mirable type silicone resin using a peroxide for vulcanization, and the like.
Furthermore, regarding the silicone resin, from the viewpoint of further suppressing changes in the hardness and impact resilience of the urethane foam, peroxide-curing silicone, condensation-type thermosetting silicone, addition-type thermosetting silicone, and cationic UV-curing. It is preferably at least one selected from the group consisting of silicone.
The silicone resin is a polymer compound having a main skeleton due to a siloxane bond, and is different from the low molecular weight siloxane compound described later.

Regarding the binder resin, in addition to the acrylic resin and the silicone resin described above, acrylics such as acrylic acid-styrene copolymer resin and acrylic acid-vinyl acetate copolymer resin can be used as long as the effects of the present invention are not impaired. Further, a system resin, polyvinyl alcohol, polyacrylamide, polyvinyl chloride resin, urethane resin, vinyl acetate resin, butadiene resin, epoxy resin, alkyd resin, melamine resin, chloroprene rubber and the like can be further contained. These components can be used alone or as a mixture of two or more.

The impregnating liquid can be used by further adding an appropriate amount of water or a solvent such as toluene or ethyl acetate in addition to the binder resin. The solvent is preferably added so that the viscosity of the impregnating liquid is about 5 to 300 cps (25 ° C.). By setting the viscosity of the impregnating liquid within the above range, the impregnation adhesion work becomes easier.

(Conducting agent)
Further, the impregnating liquid further contains a conductive agent. The conductive agent is a material that can impart conductivity to the urethane foam base material by impregnating the urethane foam base material with the binder resin. Specific examples thereof include a carbon conductive agent, an ionic conductive agent, an electronic conductive agent and the like, and these can be used alone or in combination of two or more.
Further, among the above-mentioned conductive agents, it is preferable to use a carbon conductive agent. This is because an excellent chargeability-imparting effect can be obtained while suppressing the cost.

Examples of the carbon conductive agent include gas black such as denka black, ketjen black and acetylene black, oil furnace black containing ink black, thermal black, channel black, lamp black and the like.

Further, the content of the carbon conductive agent in the conductive urethane foam of the present invention is preferably 5 to 25 parts by mass, preferably 10 to 20 parts by mass with respect to 100 parts by mass of the base material of the urethane foam. Is particularly preferred. This is because changes in the hardness and impact resilience of the urethane foam can be further suppressed while imparting good conductivity.

Regarding the ionic conductive agent, for example, tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium (for example, lauryltrimethylammonium), hexadecyltrimethylammonium, octadecyltrimethylammonium (for example, stearyltrimethylammonium), benzyltrimethylammonium, modification. Ammonium salts such as perchlorates such as fatty acid dimethylethylammonium, chlorates, hydrochlorides, bromates, iodates, borohydrochlorides, sulfates, alkyl sulfates, carboxylates and sulfonates. , Lithium, sodium, potassium, calcium, magnesium and other alkali metals and alkaline earth metals perchlorate, chlorate, hydrochloride, bromine, iodate, borohydrochloride, trifluoromethylsulfate Examples include salts and ammonium salts.

Further, examples of the electronic conductive agent include conductive metal oxides such as tin oxide, titanium oxide and zinc oxide, and metals such as nickel, copper, silver and germanium.

(Siloxane compound)
The conductive urethane foam of the present invention is characterized in that the impregnating liquid further contains a siloxane compound having a lower molecular weight.
Since the impregnating liquid contains a low molecular weight siloxane compound, the surface tension can be lowered, so that the permeation rate of the impregnating liquid into the urethane foam base material can be increased and the efficiency of the impregnation treatment can be improved. , The burden required for impregnation processing can be reduced. Further, since the impregnation treatment is performed stably and efficiently, the obtained conductive urethane foam of the present invention has no variation in resistance and can exhibit a stable chargeability imparting effect.

The siloxane compound needs to have a low molecular weight, but specifically, it is preferably 300 to 1,500, and more preferably 500 to 1,000. When the molecular weight of the siloxane compound is 300 or more, the impregnating liquid does not elute from the urethane foam base material, and when the molecular weight of the siloxane compound is 1,500 or less, the surface tension can be further lowered. Therefore, the impregnation process can be performed more efficiently and stably.

Here, the siloxane compound may be any compound having a siloxane bond, and may be unmodified or modified. Examples of the siloxane compound include polydimethylsiloxane, polyether-modified polydimethylsiloxane, and polymethylalkylsiloxane.
As for these siloxane compounds, one type may be used alone, or a plurality of types may be mixed and used.

Further, the content of the siloxane compound in the impregnating liquid is preferably 2% by mass or more, more preferably 5% by mass or more, and more preferably 8% by mass, from the viewpoint that the impregnation treatment can be performed more efficiently and stably. It is more preferably mass% or more. Further, the content of the siloxane compound in the impregnating liquid is preferably 40% by mass or less from the viewpoint of preventing saturation of the effect.

As for the impregnating liquid, other additives may be further contained in the impregnating liquid, if necessary. Examples of the additive include a defoaming agent, a surfactant, a charge control agent and the like. The content of these additives is preferably 0.001 to 10 parts by mass, and more preferably 0.001 to 1 part by mass with respect to 100 parts by mass of the impregnating solution.

<Manufacturing method of conductive urethane foam>
Next, a method for producing the conductive urethane foam of the present invention will be described.
The method for producing a conductive urethane foam of the present invention is a method for producing a conductive urethane foam, which comprises a step of impregnating the surface layer of a urethane foam base material with an impregnating solution containing a conductive agent and a binder resin a plurality of times.
The binder resin contains at least one selected from an acrylic resin and a silicone resin, and the impregnating liquid further contains a siloxane compound having a low molecular weight.
The binder resin is composed of at least one selected from acrylic resin and silicone resin, and the impregnating liquid further contains a low molecular weight siloxane compound to allow the impregnating liquid to penetrate into the urethane foam substrate. In addition to being able to increase the speed and significantly reduce the burden required for the impregnation process, the conductive urethane foam obtained as a result of being able to perform the impregnation process more efficiently and stably has no variation in resistance and is stable. The effect of imparting chargeability is realized.

The conditions of the urethane foam base material, the conductive agent, the binder resin, the siloxane compound, and the like are the same as those described in the above-mentioned conductive urethane foam of the present invention.

Further, as described above, the method for producing a conductive urethane foam of the present invention can significantly reduce the load required for the impregnation treatment, that is, reduce the number of times the impregnation liquid is impregnated into the urethane foam base material. Can be done. Specifically, from the viewpoint of more efficiently performing the impregnation treatment and reducing the burden, the number of times is preferably 3 times or less, and more preferably 2 times or less.

<Conductive roller>
The toner conductive roller of the present invention is characterized in that the above-mentioned conductive urethane foam of the present invention is used.
By using the conductive urethane foam of the present invention, it is possible to realize a toner supply roller having a high chargeability-imparting effect and excellent stability.

The conductive roller is a roller member that has conductivity and exerts a chargeability-imparting effect, and examples thereof include a toner supply roller, a charge roller, a developing roller, and a transfer roller. Among these, the conductive roller of the present invention is preferably used as a toner supply roller.

The toner supply roller is, for example, as shown in FIG. 1, a roller 13 for supplying the toner 15 to the developing roller 12, and has conductivity.
Further, FIG. 2 schematically shows an example of the toner supply roller of the present invention. In FIG. 2, the toner supply roller of the present invention supports the conductive urethane foam 3 of the present invention on the outer periphery of the shaft 1 via the adhesive layer 2.

The shaft 1 used in the toner supply roller is not particularly limited and any of them can be used. For example, a steel material such as sulfur free-cutting steel plated with nickel, zinc or the like, or a shaft 1 is used. A metal shaft made of a metal core such as iron, stainless steel, or aluminum, or a metal cylinder whose inside is hollowed out can be used. In the present invention, the diameter of the shaft 1 may be less than φ6 mm, for example, 5.0 mm, and the thickness of the conductive urethane foam 3 of the present invention may be less than 4.5 mm, for example, 4.0 mm. Suitable. As a result, the weight of the roller can be reduced, and the thin layer of the conductive urethane foam 3 of the present invention increases the elastic modulus of the urethane foam when viewed on a macro scale, and the toner scraping property is improved. Further, due to the volume reduction of the urethane foam due to the thinning of the conductive urethane foam 3 of the present invention, the amount of toner contained in the conductive urethane foam 3 of the present invention is reduced during printing durability, and the toner fuel consumption can be suppressed.

Further, in the toner supply roller, as shown in FIG. 2, it is preferable to provide an adhesive layer 2 between the shaft 1 and the charge-controlled conductive urethane foam 3. As the adhesive used for the adhesive layer 2, a heat-melt type polymer adhesive containing an adipate-based polyurethane resin having a melting point of 120 ° C. or higher, particularly 130 ° C. or higher and 200 ° C. or lower as a main component can be preferably used.
The properties of the adhesive may be any form such as a film or pellets. Further, the thickness of the adhesive layer 2 is preferably 20 to 300 μm, and if it is too thin, poor adhesion occurs, and if it is too thick, suitable roller resistance cannot be obtained, so that neither is preferable. The melting temperature of the adhesive at the time of bonding is preferably 100 ° C. or higher, particularly 130 ° C. or higher and 200 ° C. or lower, which is lower than the melting point of the adhesive. As a result, the adhesive layer 2 is in a semi-molten state, and it is easier to control the voltage dependence such that the roller resistance when ^{5 V is applied is 106 to 108 Ω and the roller resistance when 100 V is applied is 10 2 to 104 Ω} . Therefore, it is possible to increase the density at the initial stage of printing durability.

In the toner supply roller 13, for example, the conductive urethane foam 3 of the present invention is formed on the outer periphery of the shaft 1 via an adhesive as desired, and then the shaft 1 and the conductive urethane foam 3 of the present invention are formed. Can be produced by heat-bonding at a predetermined temperature.
For example, first, an impregnated solution made by mixing a binder resin and an additive is prepared, and a block-shaped (16 mm × 1000 mm × 2000 mm) urethane foam that has not been subjected to film removal treatment is placed in a bath filled with the impregnated solution. After dipping and compressing between the two rolls, it is opened and the impregnating liquid is impregnated with urethane foam. This is guided onto a bath, the excess impregnating liquid is squeezed through a nip roll, removed, and then heated and dried in a hot air furnace at 110 ° C. for 10 minutes to prepare a charge-controlled urethane foam 3. The conductive urethane foam 3 of the present invention that can be molded by this method has a lower hardness than that obtained by mechanical gas filling, specifically, an Asker F hardness of 30 to 90 °.

Further, a film-like adhesive is wound around the outer periphery of the shaft 1, or a pellet-like adhesive is melted and applied to form an adhesive film. After that, a hole is made in the conductive urethane foam 3 of the present invention, and the shaft 1 with an adhesive is inserted into the hole. After that, heating is performed at a predetermined temperature to integrate the shaft 1 and the conductive urethane foam 3 of the present invention via the adhesive layer 2, and the surface of the conductive urethane foam 3 of the present invention is polished to obtain a desired cylinder. The toner supply roller 13 can be obtained by forming the shape and further cutting the end portion of the conductive urethane foam 3 of the present invention into a predetermined shape.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

(Samples 1-8)
Under the conditions shown in Table 1, 18% by mass is applied to the surface layer of a urethane foam base material (manufactured by Bridgestone Co., Ltd., density 55 kg / m ³ , hardness 80 (Ask-F), breathability 100 cc / cm ² / sec). Conductive agent (carbon black: "PSM Black A898" manufactured by Mikuni Color Co., Ltd., solid content 40%) 7% by mass binder resin (acrylic resin (acrylic nitrile / alkyl acrylate copolymer emulsion): Enex Co., Ltd. A sample of conductive urethane foam was prepared by impregnating with an impregnating solution containing the additive of "BS-050301-1" manufactured by Japan, 50% solid content) and the additives shown in Table 1. The number of times the impregnation treatment was performed is shown in Table 1.
Then, the following evaluations were performed on each sample of the prepared conductive urethane foams of Examples and Comparative Examples.

(Evaluation of chargeability imparting effect)
The resistance value (LogΩ · cm) of each sample of the conductive urethane foam was measured using "Loresta GX MCP-T700" manufactured by Mitsubishi Chemical Analytech Co., Ltd. under the condition of an applied voltage of 90V. The measurement was performed 5 times for each sample, and the average value is shown in FIG.

* 1 Polyoxyethylene alkyl ether, "Leocol SC-90" manufactured by Lion Specialty Chemicals Co., Ltd., molecular weight: 923
* 2 Polyether-modified polydimethylsiloxane, "BYK349" manufactured by BYK, molecular weight: 901 to 1640
* 3 Polyether-modified polydimethylsiloxane, "BYK3450" manufactured by BYK, molecular weight: 808
* 4 Polyether-modified polydimethylsiloxane, "BYK3451" manufactured by BYK, molecular weight: 941

From the results of Table 1 and FIG. 3, the conductive urethane foams of each example have lower resistance and conductivity than the conductive urethane foams of Comparative Example 1 despite the two impregnation operations. It turned out to be excellent. On the other hand, in each sample of the comparative example, it can be seen that although a certain degree of conductivity can be obtained by performing the impregnation operation 9 times (Sample 2), good conductivity cannot be obtained in either of the 2 impregnation operations. ..

According to the present invention, it is possible to provide a method for producing a conductive urethane foam and a method for producing a conductive urethane foam, in which the burden required for the impregnation treatment of the conductive agent is small and a stable chargeability imparting effect is realized. Further, according to the present invention, it is possible to provide a toner supply roller having a high chargeability-imparting effect and excellent stability.

1 Axis 2 Adhesive layer 3 Conductive urethane foam 11 Image forming body 12 Developing roller 13 Toner supply roller 14 Toner accommodating part 15 Toner

Claims (9)

A conductive urethane foam in which the surface layer of a urethane foam base material is impregnated with an impregnating liquid containing a conductive agent and a binder resin.
The binder resin contains at least one selected from acrylic resin and silicone resin.
A conductive urethane foam, wherein the impregnating liquid further contains a low molecular weight siloxane compound. The conductive urethane foam according to claim 1, wherein the siloxane compound has a molecular weight of 500 to 1,000. The conductive urethane foam according to claim 1 or 2, wherein the content of the siloxane compound in the impregnating liquid is 2% by mass or more. The conductive urethane foam according to any one of claims 1 to 3, wherein the binder resin contains at least an acrylic resin. A method for producing a conductive urethane foam, which comprises a step of impregnating the surface layer of a urethane foam base material with an impregnating liquid containing a conductive agent and a binder resin multiple times.
The binder resin contains at least one selected from acrylic resin and silicone resin.
A method for producing a conductive urethane foam, wherein the impregnating liquid further contains a low molecular weight siloxane compound. The method for producing a conductive urethane foam according to claim 5, wherein the urethane foam base material is impregnated with the impregnating liquid three times or less. The method for producing a conductive urethane foam according to claim 5 or 6, wherein the siloxane compound has a molecular weight of 500 to 1,000. A conductive roller according to any one of claims 1 to 4, wherein the conductive urethane foam is used. The conductive roller according to claim 8, wherein the conductive urethane foam constitutes an outermost layer of the conductive roller.

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