JP3653122B2 - Conductive roller - Google Patents

Description

【００４５】
比較例４以外の全ての例ではジメチルシロキサンのポリオール成分への分散性は許容できる範囲であった。
【００４６】
比較例１は低硬度の導電弾性層の焼付きによる砥石の目詰まりが、また、比較例２〜５においては、ジメチルシロキサンのブリードがいずれも認められたのでローラとして機能しないため、研磨砥石のドレッシングの検討は行っていない。
【００４７】
表１の結果から明らかなように、ジメチルシロキサンを前記所定範囲内で配合する限り、ブリードは見られなかった。さらに本発明の導電性ローラは表面粘着性において比較例のそれらより優れ、研磨機の砥石のドレッシング回数も実施例のローラに関しては顕著に減少した。
【００４８】
【発明の効果】
以上のように本発明の導電性ローラは、ポリウレタン生成用調合物に粘度調製したジメチルシロキサンを配合し、硬化成形したことにより、ローラ表面の粘着性が低下し、トナーの不要な付着がなくなるとともに、望ましくない埃やくず等の表面への付着も防止することができる。また、研磨時の砥石表面のつまりも減少し、砥石表面も比較的長時間奇麗に保てるので必要なドレッシングの周期が長くなり（すなわち回数が減り）研磨作業性が飛躍的に向上した。したがって本発明は工業上極めて利用価値がある。[0001]
[Industrial application fields]
The present invention relates to a conductive roller, and more particularly, to a low hardness, low surface adhesive conductive roller that can be used in an electrophotographic apparatus or the like.
[0002]
[Prior art]
An electrophotographic apparatus such as a copying machine, a facsimile machine, or a printer is generally provided with an elastic roller having conductivity suitable for the purpose in order to charge a photosensitive member or to visualize an electrostatic latent image. For example, in a one-component developing type electrophotographic apparatus, a developer (toner) moves from a developing roller pressed against each other to a photosensitive drum (photosensitive member), and an electrostatic latent image is visualized and developed. . Such a developing roller needs to have elasticity because it is pressed against the photosensitive drum with a predetermined contact width or is loaded with a thin layer of developer by a blade or the like, and typically has a rotating shaft (metal core). A roller having a conductive elastic layer formed of an elastic body (elastomer) or a foamed body (foam) having a low hardness and containing a conductivity imparting agent is used. For the conductive elastic layer of these rollers, a polyurethane elastomer or foam is preferably used from the viewpoint of being easily deformed and excellent in resilience and not contaminating the photoreceptor.
[0003]
For such a conductive elastic layer, 1) low hardness (for example, JIS A 20-30 °), 2) good conductivity (for example, 10 7 Ω or less), 3) low adhesiveness, and 4) molded into a roller. Sometimes characteristics such as low surface roughness are required. However, known low-hardness polyurethane has a drawback of high surface tackiness. When the surface adhesiveness is high, the grindstone is likely to be clogged when the roller is polished, or the grindstone surface becomes sticky. When the grindstone is clogged, the roller cannot be polished to a predetermined size, and the surface of the polished roller becomes rough. Further, the clogging and stickiness of the grindstone increases the frequency of dressing (cleaning) of the grindstone, resulting in a decrease in workability.
[0004]
Another problem when the surface adhesiveness is high is that the toner adheres to the roller surface and the toner is not smoothly transferred to the photoreceptor.
[0005]
[Problems to be solved by the invention]
As described above, the conventional low-hardness polyurethane elastomer has high surface adhesiveness, and thus has various problems when used as a conductive roller.
[0006]
An object of the present invention is to provide a conductive roller made of a low hardness polyurethane elastomer having low surface tackiness.
[0007]
[Means for Solving the Problems]
The gist of the present invention is a conductive roller provided with an elastic layer made of a low-hardness conductive polyurethane elastomer whose surface tackiness is improved by blending dimethylsiloxane having a predetermined viscosity.
[0008]
According to the present invention, in the conductive roller in which the rotating shaft and the low hardness conductive elastic layer are concentrically laminated and integrated on the outer periphery thereof, the low hardness conductive elastic layer is 100 parts by weight in total of the polyol component and the isocyanate component. In contrast, there is provided a conductive roller comprising a polyurethane elastomer which is reacted and cured by containing 0.5 to 10 parts by weight of dimethylsiloxane having a viscosity at 25 ° C. of 100,000 to 800,000 cps. .
[0009]
As used herein, the term “conductive roller” refers to a concentrically laminated conductive elastic layer made of low-hardness conductive polyurethane elastomer on the outer periphery of a rotating shaft that has been subjected to surface treatment such as rust prevention on a rigid body such as metal. It means a roller provided with a surface layer that covers the outer periphery of the conductive elastic layer so as to be formed integrally and to impart surface performance as required. Here, “low hardness” refers to a hardness of 40 ° or less of JISA.
[0010]
The polyurethane elastomer that can be used in the present invention is obtained by reacting and curing a polyurethane-forming preparation containing an isocyanate and a polyol as essential components and, if necessary, a chain extender and a crosslinking agent. As the isocyanate, either aliphatic or aromatic may be used. For example, preferred isocyanates include tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (hydrogenated MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 1,3. -Xylylene diisocyanate, 1,4-xylylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate and modified products thereof Is mentioned. The “modified product” used in the present specification means a dimer, a trimer, a urea-modified product, etc. obtained by reacting the above isocyanate monomers with each other. These isocyanates can be used alone or as a mixture of two or more.
[0011]
In a preferred embodiment of the invention, the isocyanate used is liquid at ambient temperature (about 10 to about 40 ° C.). Particularly preferred are TDI, modified MDI, hydrogenated MDI, HDI and IPDI.
[0012]
The polyols that can be used in the present invention are roughly composed of polyether polyols and polyester polyols. Examples of polyether polyols include polyethylene polyether glycol, polypropylene ether glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, polyoctamethylene ether glycol, polydecamethylene ether glycol, and mixtures thereof. As the polyol, one having three hydroxyl groups in one molecule, for example, polypropylene ether triol can be used. Examples of the polyester glycol include those obtained by first reacting a dibasic acid with glycol. Examples of the dibasic acid used here include adipic acid, succinic acid, sebacic acid, terephthalic acid, alkyl derivatives and halogen derivatives of these acids, and ethylene glycol, diethylene glycol, propylene glycol and the like are used as the glycol. Furthermore, polycaprolactone polyol by ring-opening polymerization of lactone can also be used. These polyols can be used alone or as a mixture of two or more.
[0013]
Like the isocyanate, it is preferable to use a polyol that is liquid at room temperature. Particularly preferred are polypropylene ether glycol, polypropylene ether triol, β-methyl-δ-valerolactone polyol, and 3-methyl-pentylene adipate.
[0014]
In the present invention, the reason why polyols and isocyanates that are liquid at room temperature are preferably used is that when they are liquid at room temperature, operations such as metering, mixing, casting, etc. are easy to perform and not only are safe, but also save on utility costs. Because it will be.
[0015]
In addition to isocyanates and polyols, chain extenders can also be used. As the chain extender, any conventionally known one may be used, but they are roughly classified into a hydroxy chain extender and an amine chain extender. Representative examples of the hydroxy chain extender include ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol and the like. Typical examples of the amine chain extender include ethylenediamine, 1,2-propylenediamine, tetramethylenediamine, hexamethylenediamine, decamethylenediamine, isophoronediamine, m-xylylenediamine, hydrazine and the like.
[0016]
In addition, a crosslinking agent may be added to the polyurethane formulation used in the present invention. As with the chain extender, the crosslinking agent includes a hydroxy crosslinking agent and an amine crosslinking agent. Representative examples of hydroxy crosslinkers are glycerin and trimethylolpropane and other alkylene triols. Representative examples of amine crosslinking agents are alkanolamines such as diethanolamine, triisopropanolamine and the like.
[0017]
In order to impart conductivity to the polyurethane elastomer according to the present invention, a conductivity-imparting material is added to the polyurethane-forming preparation. Examples of the conductivity imparting material include known carbon black and metal particles such as tin oxide particles. The amount used is 0.3 to 2.0 parts by weight, preferably about 0.5 parts by weight, based on 100 parts by weight of the polyol component.
[0018]
[Action]
In order to reduce the surface tackiness of the low-hardness polyurethane elastomer that forms the low-hardness conductive elastic layer of the conductive roller, the inventors of the present invention blend a certain amount of dimethylsiloxane with a predetermined viscosity together with a conductivity-imparting agent into the polyol component. The inventors have found that the initial purpose can be achieved by reactive curing, thus completing the present invention.
[0019]
A prominent feature of the present invention is that the formulation for producing polyurethane is reacted and cured by blending dimethylsiloxane having a specific ratio of a specific ratio with respect to the total of the polyol component and the isocyanate component in the polyurethane formulation. It is to obtain a polyurethane elastomer. The viscosity of the dimethylsiloxane used is preferably in the range of about 100,000 to about 800,000 cps at 25 ° C. When the viscosity is less than 100,000 cps, dimethylsiloxane bleeds and toner filming occurs (the toner adheres to the roller), and when it exceeds 800,000 cps, it does not disperse well in the polyurethane elastomer.
[0020]
About the compounding quantity of dimethylsiloxane, about 0.5 to about 10 weight part is preferable with respect to a total of 100 weight part of the said polyol component and isocyanate component. When the amount is less than about 0.5 part by weight, the problem of the decrease in the surface tackiness of the roller is not recognized. When the amount exceeds about 10 parts by weight, the compatibility with the polyurethane preparation is poor, and bleeding of dimethylsiloxane is observed.
[0021]
The polyurethane elastomer constituting the low hardness conductive elastic layer of the conductive roller of the present invention can be produced by a known method using the raw materials. For example, the above-mentioned polyol component is mixed with a conductivity-imparting agent component and, if desired, a catalyst and other additional components to prepare a polyurethane-forming preparation and reaction-cured to obtain a polyurethane elastomer. Examples of additional components that can be used in the present invention are colorants, flame retardants, antioxidants, mold release agents and the like. In order to accelerate the polymerization reaction, an amine catalyst (triethylamine, N-ethylmorpholine, triethylenediamine, etc.) and a tin catalyst (trimethyltin laurate, dibutyltin dilaurate, etc.) used in ordinary urethane polymerization reactions are used. May be.
[0022]
As described above, the urethanization reaction is carried out in the absence of a solvent by adding a conductive property-imparting material and dimethylsiloxane, which is a feature of the present invention, to a polyol that is liquid at room temperature and then uniformly mixing it with a liquid isocyanate at room temperature. It is desirable.
[0023]
The conductive roller of the present invention can be produced by injecting and filling a polyurethane-forming preparation into a mold and curing at the reaction temperature. That is, the formulation is placed in an ambient temperature mold and, after filling, the mold is heated to a temperature of about 70 to about 180 ° C. According to another embodiment, after filling the formulation into a mold preheated to about 80 ° C., the mold is similarly heated to about 150 ° C. for curing. In either case, heating of the mold is accomplished by placing the mold in an oven set at a temperature slightly higher than the desired mold temperature. The mold temperature is maintained at about 70 to about 180 ° C, preferably about 80 to about 150 ° C. In a typical method, an in-mold cure time of 5-60 minutes is appropriate. After curing, the die is removed by a conventional method to obtain a molded roller. The roller of the present invention is useful as a conductive roller for an electrophotographic apparatus, but can also be applied to a conductive roller for various other uses.
[0024]
【Example】
The following examples illustrate the invention by way of examples and comparative examples, but do not limit the scope of the invention. All parts are by weight except as otherwise indicated.
[0025]
Example 1
99.5 parts of polyester polyol (Nipporan 4032, manufactured by Nippon Polyurethane Co., Ltd.), 0.5 part of dimethylsiloxane (KF96H100,000, viscosity at 25 ° C., 100,000 cps, manufactured by Shin-Etsu Silicon Co., Ltd.), conductive carbon black ( After mixing and stirring well with 0.5 part (manufactured by Lion Akzo Co., Ltd.), it was kneaded with a roll. After the mixture became uniform, it was dehydrated under reduced pressure at 105 ° C. and a pressure of 3 Torr or less for 5 hours.
[0026]
7.5 parts of isocyanate (TDI-80, manufactured by Nippon Polyurethane Co., Ltd.) was added to the polyol component mixture prepared as described above (liquid temperature 105 ° C.) while maintaining the liquid temperature at 40 ° C., and the mixture was stirred with an agitator. A formulation for producing polyurethane was obtained.
[0027]
A metal core (rotary shaft) made of stainless steel (SUS303) coated with an adhesive on the outer periphery was set in a roller molding die and heated to 150 ° C. The mold was poured with a polyurethane-forming formulation, reacted and cured for about 60 minutes, and then demolded. After demolding, a cross-linking reaction was further performed at 150 ° C. for 2 hours to obtain a molded body having a conductive elastic layer on the outer periphery of the rotating shaft, and the obtained molded body was aged for 1 day at room temperature. This molded body is set in a polishing machine, rotated at 130 rpm, and while being laterally fed at a speed of 7 mm / s, the outer surface of the molded body is applied with a grindstone rotating at a peripheral speed of 1700 m / s to perform surface polishing. A conductive roller was obtained.
[0028]
Example 2
A molded body having a conductive elastic layer on the outer periphery of the rotating shaft was obtained in the same manner as in Example 1 except that the amount of dimethylsiloxane added was 10 parts in Example 1. This was subjected to surface polishing under the polishing conditions described in Example 1 to obtain a conductive roller.
[0029]
Example 3
A molding having a conductive elastic layer on the outer periphery of the rotating shaft in the same manner as in Example 1 except that DKQ8-770 (manufactured by Dow Corning, viscosity 800,000 cps at 25 ° C.) was used as dimethylsiloxane in Example 1. Got the body. The molded body was surface-polished as described above to obtain a conductive roller.
[0030]
Example 4
In Example 1, a molding having conductive elasticity on the outer periphery of the rotating shaft in the same manner as in Example 1 except that 10 parts of DKQ8-770 (manufactured by Dow Corning Co., Ltd., viscosity of 800,000 cps at 25 ° C.) was used as dimethylsiloxane. Got the body. The molded body was surface-polished as described above to obtain a conductive roller.
[0031]
Example 5
In Example 1, except that KF96H500,000 (manufactured by Shin-Etsu Silicon Co., Ltd., viscosity of 500,000 cps at 25 ° C.) was used as dimethylsiloxane, molding having conductive elasticity on the outer periphery of the rotating shaft in the same manner as in Example 1. Got the body. The molded body was surface-polished as described above to obtain a conductive roller.
[0032]
Comparative Example 1
In Example 1, a conductive roller was obtained in the same manner as in Example 1 except that the addition amount of dimethylsiloxane was 0.2 part.
[0033]
Comparative Example 2
In Example 1, a conductive roller was obtained in the same manner as in Example 1 except that the amount of dimethylsiloxane added was 15 parts.
[0034]
Comparative Example 3
In Example 1, a conductive roller was obtained in the same manner as in Example 1 except that 15 parts of DKQ8-770 was used as dimethylsiloxane.
[0035]
Comparative Example 4
In Example 1, a preparation liquid for polyurethane production was prepared in the same manner as in Example 1 except that KF96H1,000,000 (manufactured by Shin-Etsu Silicon Co., Ltd., viscosity 1,000,000 cps at 25 ° C.) was used as dimethylsiloxane. Attempts were made to carry out the urethane curing reaction because dimethylsiloxane was not dispersed in the polyol component.
[0036]
Comparative Example 5
In Example 1, a conductive roller was obtained in the same manner as in Example 1 except that KF96H60,000 (manufactured by Shin-Etsu Silicon Co., Ltd., viscosity of 60,000 cps at 25 ° C.) was used as dimethylsiloxane.
[0037]
Comparative Example 6
A conductive roller was obtained in the same manner as in Example 1 except that no dimethylsiloxane was used in Example 1.
[0038]
Table 1 shows the results of the following characteristic tests on the respective conductive rollers obtained from the comparative examples from the above examples.
[0039]
a) The presence or absence of dimethylsiloxane bleed from a dimethylsiloxane bleed roller was observed with the naked eye.
[0040]
b) When the surface adhesive roller was loaded into an electrophotographic apparatus (copier) and actually used, the presence or absence of adhesion of toner onto the roller surface was used, and then the roller was removed and visually confirmed.
[0041]
Evaluation of manufacturing characteristics Table 1 shows the results of evaluation of manufacturing points in the examples and comparative examples as follows.
[0042]
a) Dispersibility of dimethylsiloxane into polyol component It was visually checked whether it was uniformly dispersed or poorly dispersed during kneading.
[0043]
b) Grinding wheel dressing frequency (interval)
The required dressing (cleaning) frequency of the grindstone provided in the polishing machine was evaluated by the number of rollers that could be polished between dressings.
[0044]
[Table 1]

[0045]
In all examples other than Comparative Example 4, the dispersibility of dimethylsiloxane in the polyol component was in an acceptable range.
[0046]
In Comparative Example 1, clogging of the grindstone due to seizure of the electroconductive elastic layer having a low hardness was observed, and in Comparative Examples 2 to 5, since any dimethylsiloxane bleed was observed, it did not function as a roller. We are not considering dressing.
[0047]
As is clear from the results in Table 1, no bleed was observed as long as dimethylsiloxane was blended within the predetermined range. Furthermore, the conductive roller of the present invention is superior to those of the comparative example in surface adhesion, and the number of dressings of the grinder of the polishing machine is significantly reduced with respect to the roller of the example.
[0048]
【The invention's effect】
As described above, the conductive roller of the present invention is obtained by blending dimethylsiloxane having a viscosity adjusted to a polyurethane-generating preparation and curing and molding, thereby reducing the adhesiveness of the roller surface and eliminating unnecessary adhesion of toner. Further, it is possible to prevent unwanted dust and debris from adhering to the surface. Also, the clogging of the grindstone surface during polishing is reduced, and the grindstone surface can be kept clean for a relatively long time, so that the required dressing cycle is lengthened (that is, the number of times is reduced), and the polishing workability is dramatically improved. Therefore, the present invention is extremely useful industrially.

Claims (1)

In a conductive roller in which a rotating shaft and a low-hardness conductive elastic layer are concentrically laminated and integrated on the outer periphery thereof, the low-hardness conductive elastic layer is 25 ° C. with respect to a total of 100 parts by weight of a polyol component and an isocyanate component. A conductive roller comprising a polyurethane elastomer obtained by reacting and curing 0.5 to 10 parts by weight of dimethylsiloxane having a viscosity of 100,000 to 800,000 cps.