JP2009098669A - Conductive rubber member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive rubber member which does not cause staining of an OPC or the like and leakage, which has traceability to deformation and exhibits a small variation in electrical resistance. <P>SOLUTION: The conductive rubber member has a surface-treated layer 12a formed through impregnating a surface-treatment liquid containing at least an isocyanate component and an organic solvent on a surface layer of the conductive elastic layer 12 of an outermost layer to which conductivity is imparted. In an upper layer portion 12b on the surface side of the surface-treated layer 12a, a density of the isocyanate component is greater on the inner side than on the surface side and in a lower layer portion 12c beneath the upper layer portion 12b, the density of the isocyanate component that gradually decreases toward the inner part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a charging roll, a transfer roll, a developing roll, a toner supply roll, a conductive roll such as a cleaning roll, and a cleaning roll used in an image forming apparatus such as an electrophotographic copying machine and printer or a toner jet copying machine and printer The present invention relates to a conductive rubber member particularly suitable for a blade, a transfer belt and the like.

Conductive rubber rolls having rubber elasticity and controlled conductivity are important in the electrophotographic process, but the molecules constituting the rubber itself have a resistivity (10 ⁴ to 10 ⁹ Ωcm) required by the process. Is rare as a specific resistance value, and only a very limited number such as epichlorohydrin has been put to practical use. In many cases, in order to maintain the required elastic modulus, mechanical strength, and temperature and humidity characteristics, carbon black and other materials such as silicone rubber, ethylene / propylene rubber (EPDM), and polyurethane are used. After imparting conductivity by adding conductive fine particles, a coating layer is formed for preventing contamination such as OPC, adjusting resistance, and preventing electrical leakage.

  In recent years, the toner binder used in electrophotographic copying machines has been lowered in melting point, and accordingly, the developing roll has been lowered in hardness to form a sufficient nip to ensure toner charging. Is required. In order to satisfy the above-described requirements, there has been proposed a developing roll composed of an elastic layer, a coat layer made of urethane resin, and a thin cured layer made of isocyanate, and having a hard surface while keeping the whole soft (for example, Patent Documents) 1).

  On the other hand, the formation of the coating layer has the disadvantage that the process becomes complicated and the production cost increases, and as a means for easily solving this problem, a method of chemically treating the roll surface layer has been proposed. (For example, refer to Patent Document 2). Although this treatment method is effective, the conductive roll subjected to the surface treatment tends to have a hard surface layer. In the case of a roll having a reduced hardness, the surface layer portion of the roll is greatly deformed during use, so that it is necessary to follow the deformation. However, a roll having a hard surface layer has poor trackability, and is suitable for OPC. There is a risk of damage, and there is a problem that the electric resistance value changes due to use.

Therefore, a conductive roll that does not have high hardness even when a surface treatment layer is formed has been proposed (see Patent Document 3). However, in this case, specifically, for example, a relatively thin surface treatment layer is formed using a surface treatment liquid that is relatively difficult to impregnate the conductive elastic layer, and the effect as the surface treatment layer is sufficiently high. In some cases, it could not be obtained, and in some cases, it was not a sufficient response.
JP-A-2005-283913 JP-A-5-158341 JP 2007-199694 A

  In view of such circumstances, it is an object of the present invention to provide a conductive rubber member that is free from contamination and leakage problems such as OPC, has followability to deformation, and has a small change in electrical resistance value. .

  The first aspect of the present invention that solves the above-mentioned problems is formed by impregnating a surface treatment liquid containing at least an isocyanate component and an organic solvent in the surface layer portion of the outermost conductive elastic layer to which conductivity is imparted. A conductive rubber member having a surface-treated layer, wherein the density of the isocyanate component is larger in the interior than the surface in the upper layer portion on the surface side of the surface-treated layer, and in the lower layer portion on the lower side of the upper layer portion, The conductive rubber member is characterized in that the density of the isocyanate component gradually decreases toward the inside.

  According to a second aspect of the present invention, in the conductive rubber member according to the first aspect, at least the surface treatment liquid is selected from the group consisting of carbon black, an acrylic fluorine-based polymer, and an acrylic silicone-based polymer. The conductive rubber member is characterized by containing one.

  According to a third aspect of the present invention, there is provided the conductive rubber member according to the first or second aspect, wherein the surface treatment liquid further contains a polyether polymer. It is in.

  According to a fourth aspect of the present invention, there is provided the conductive rubber member according to the third aspect, wherein the polyether polymer has active hydrogen.

  According to a fifth aspect of the present invention, there is provided the conductive rubber member according to the fourth aspect, wherein the polyether polymer is epichlorohydrin rubber.

  According to a sixth aspect of the present invention, in the conductive rubber member according to any one of the first to fifth aspects, the conductive elastic layer is formed of at least one of an electronic conductivity imparting material and an ionic conductivity imparting material. The conductive rubber member is provided with conductivity.

  A seventh aspect of the present invention resides in a conductive rubber member, wherein the conductive rubber member according to any one of the first to sixth aspects is in a roll shape or a blade shape.

  According to the present invention, it is possible to provide a conductive rubber member that is free from contamination and leakage problems such as OPC, has followability to deformation, and has a small change in electrical resistance value.

  The conductive rubber member of the present invention is a conductive rubber member having a surface treatment layer formed by impregnating a surface treatment liquid on a surface layer portion of a conductive elastic layer imparted with conductivity. The surface treatment layer to be formed on the surface layer part has a higher density of the isocyanate component in the upper layer part than in the surface, and the density of the isocyanate component in the lower layer part below the upper layer part gradually decreases toward the inside. As a result, the lower surface portion of the surface treatment layer performs the functions of adjusting the electrical resistance value and preventing leakage as well as preventing bleeding from the inside of the pollutant as in the conventional case, and the surface treatment of the upper layer. The upper layer part of the layer can suppress the increase in hardness of the outermost layer part, and can follow deformation, minimizing damage to the mating member such as OPC. It has been completed based on the finding that.

  FIG. 1 shows a cross-sectional view of a conductive roll as an example of the conductive rubber member of the present invention. As shown in FIG. 1, the conductive roll 10 has a conductive elastic layer 12 formed by adding a conductivity-imparting material to a rubber base material and vulcanized on a core metal 11. The surface layer portion is a surface treatment layer 12a formed using a surface treatment liquid containing an isocyanate component and an organic solvent. Here, the surface treatment layer 12a is composed of an upper layer portion 12b on the surface side and a lower layer portion 12c below it. The upper layer portion 12b is a region where the density of the isocyanate component impregnated is larger in the interior than the surface, and the density of the isocyanate component is larger, for example, from the surface toward the inside, and the lower layer portion 12c is the density of the isocyanate component. Is a region that gradually decreases from the surface side toward the inside. Here, the presence of the upper layer portion 12b means that there is a region where the density of the isocyanate component is larger on the inside than the surface side, and conversely, if there is a region where the density of the isocyanate component is smaller on the surface side. The isocyanate component may not be substantially present at least on the outermost surface of the upper layer portion 12b. In addition, such an upper layer portion 12b does not have a problem with the boundary with the lower layer portion 12c, and it is only necessary that the upper layer portion 12b forms a state in which the surface layer has a lower hardness than the inside. Moreover, since the upper layer part 12b exists in order to make the hardness of the outermost layer low (hardness lower than the lower layer part 12c), the thickness is at least 1 μm or more, preferably 10 μm or more. It is particularly preferable that the upper layer portion 12b exists in a region that is deformed and forms a nip at the time of use. For example, the thickness is preferably about 10 to 100 μm. Moreover, it is preferable that the lower layer part 12c is about 100-1000 micrometers in thickness. The thicknesses of the upper layer portion 12b and the lower layer portion 12c can be predicted by, for example, polishing the surface of the conductive rubber member and measuring the rubber hardness and electric resistance value at each portion.

  Moreover, although the conductive roll 10 shown in FIG. 1 has one elastic layer 12, if an elastic layer having the same structure as the elastic layer 12 is present in the outermost layer, one or more lower layers are provided below the elastic layer. May exist. The lower layer may be a foamed layer or a non-foamed layer, and is not particularly limited. That is, the conductive roll included in the present invention includes a plurality of conductive rolls.

  The elastic layer 12 of the conductive roll 10 of the present invention is formed by adding a conductivity-imparting material to a rubber substrate and molding and vulcanizing it. Here, examples of the rubber base material include polyurethane, epichlorohydrin rubber, nitrile rubber (NBR), styrene rubber (SBR), and chloroprene rubber.

  Further, as the conductivity imparting material, an electron conductivity imparting material such as carbon black or metal powder, an ion conductivity imparting material, or a mixture of both can be used. Examples of the ion conductivity-imparting material include organic salts, inorganic salts, metal complexes, ionic liquids, and the like. Examples of organic salts and inorganic salts include lithium perchlorate, quaternary ammonium salts, and sodium trifluoride acetate. Moreover, as a metal complex, halogenated ferric-ethylene glycol etc. can be mentioned, Specifically, what was described in the patent 3655364 can be mentioned. On the other hand, the ionic liquid is a molten salt that is liquid at room temperature, and is also called a room temperature molten salt, and particularly refers to a melting point of 70 ° C. or lower, preferably 30 ° C. or lower. Specific examples include those described in JP-A No. 2003-202722.

  The method for manufacturing the surface treatment layer 12a is not particularly limited. For example, the surface treatment layer 12a may be formed by removing a part of the surface treatment liquid that has penetrated into the elastic layer 12 after the surface treatment liquid has penetrated into the elastic layer 12. it can. Specifically, the elastic layer 12 is immersed in the first surface treatment liquid containing an isocyanate component, or the first surface treatment liquid is applied to the elastic layer 12 by spray coating or the like. After performing the first treatment for infiltrating the surface treatment liquid, the elastic layer 12 is not subjected to an isocyanate component, or the concentration of the isocyanate component is significantly lower than that of the first surface treatment liquid. It can be formed by performing a second treatment for removing the isocyanate component impregnated on the outermost surface by immersing in this surface treatment solution or washing with this second surface treatment solution, followed by drying and curing.

  Such two-stage treatment may be performed continuously or in a separate process, but after the first treatment with the first surface treatment liquid, the second surface is treated before the isocyanate component is cured. It is necessary to perform the second treatment with the treatment liquid. In order to uniformly perform the second treatment after the first treatment over the entire surface of the elastic layer, it is more preferable that the organic solvent remaining on the surface of the elastic layer is not volatilized after the first treatment. It is preferable to continuously perform the second treatment without exposing to air.

  As a continuous two-stage process, after immersing the elastic layer in the first surface treatment liquid, a method of spraying the second surface treatment liquid while pulling up the elastic layer, the first surface treatment liquid and the second surface treatment liquid are used. And a method (phase separation method) in which the elastic layer is moved from the first surface treatment liquid to the second surface treatment liquid. In the phase separation method, after the elastic layer is immersed in the first surface treatment liquid, the second surface treatment liquid is poured onto the first surface treatment liquid to form a layer, and then the elastic layer is formed into the second layer. It can be performed by passing through the surface treatment liquid and pulling it up.

  On the other hand, in order to perform the second surface treatment in a separate process uniformly over the entire surface of the elastic layer, the organic solvent remains on the entire surface of the elastic layer before the organic solvent remaining on the surface of the elastic layer is not volatilized. It is preferable to perform the second treatment in a state where it is almost uniformly volatilized (semi-dry state). This is because if there is a difference in the dried state of the organic solvent on the surface of the elastic layer, there is a risk of uneven processing.

  Here, the first surface treatment liquid is obtained by dissolving at least an isocyanate component in an organic solvent.

  Examples of the isocyanate component contained in the first surface treatment liquid include 2,6-tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), paraphenylene diisocyanate (PPDI), 1,5-naphthalene diisocyanate ( NDI) and 3,3-dimethyldiphenyl-4,4'-diisocyanate (TODI), and the aforementioned multimers and modified products. Furthermore, the prepolymer which consists of a polyol and isocyanate can be mentioned.

  Here, the organic solvent used for the first surface treatment liquid is particularly suitable as long as it dissolves an isocyanate component, a polyether-based polymer, an acrylic fluorine-based polymer, and an acrylic silicone-based polymer, which will be described later, if necessary. Although not limited, it is preferable to use a material that is relatively easily impregnated into the elastic layer 12 and that swells the elastic layer 12, and varies depending on the type of rubber substrate, but includes ethyl acetate, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK). An organic solvent such as toluene may be used. In the case of the phase separation method, depending on the solvent used for the second surface treatment liquid, for example, an aprotic polar solvent that phase-separates with a nonpolar solvent such as hexane may be used as the first surface treatment liquid. For example, an organic solvent such as N-methylpyrrolidone, N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or acetonitrile may be used.

  In addition, the first surface treatment liquid may contain a polyether polymer. Here, the polyether polymer is preferably soluble in an organic solvent, and preferably has active hydrogen and can be chemically bonded by reacting with an isocyanate component.

  Examples of suitable polyether polymers having active hydrogen include epichlorohydrin rubber. The epichlorohydrin rubber here refers to an unvulcanized state. Epichlorohydrin rubber is preferable because it can impart elasticity to the surface treatment layer as well as conductivity. The epichlorohydrin rubber has an active hydrogen (hydroxyl group) at the terminal, but preferably has a unit having an active hydrogen such as a hydroxyl group or an allyl group. Examples of the epichlorohydrin rubber include an epichlorohydrin homopolymer, an epichlorohydrin-ethylene oxide copolymer, an epichlorohydrin-allyl glycidyl ether copolymer, an epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer and a derivative thereof. it can.

  Examples of other suitable polyether polymers having active hydrogen include polymers having a hydroxyl group or an allyl group, such as polyols and glycols. Such a polyether polymer preferably has only one terminal rather than one having active hydrogen groups at both terminals. Moreover, it is preferable that a number average molecular weight is 300-1000. This is because elasticity can be imparted to the surface treatment layer. Examples of such polyether polymers include polyalkylene glycol monomethyl ether, polyalkylene glycol dimethyl ether, allylated polyether, polyalkylene glycol diol, polyalkylene glycol triol, and the like.

  By adding a polyether-based polymer to the surface treatment liquid in this way, the flexibility and strength of the surface treatment layer are improved. As a result, the surface of the conductive rubber member is worn or the contacted photoreceptor surface is damaged. There is no risk of being lost.

  Further, the first surface treatment liquid may contain a polymer selected from an acrylic fluorine polymer and an acrylic silicone polymer.

  The acrylic fluorine-based polymer and the acrylic silicone-based polymer used in the first surface treatment liquid are soluble in a predetermined solvent and can be chemically bonded by reacting with an isocyanate component. The acrylic fluorine-based polymer is, for example, a solvent-soluble fluorine-based polymer having a hydroxyl group, an alkyl group, or a carboxyl group, and examples thereof include block copolymers of acrylic acid esters and fluorinated alkyl acrylates and derivatives thereof. . The acrylic silicone polymer is a solvent-soluble silicone polymer, and examples thereof include block copolymers of acrylic acid esters and acrylic acid siloxane esters, and derivatives thereof.

  In addition, carbon black such as acetylene black, ketjen black, and talker black may be further added to the first surface treatment liquid as a conductivity imparting material.

  The carbon black used in the first surface treatment liquid is preferably 0 to 40% by mass with respect to the isocyanate component. If the amount is too large, problems such as dropout and deterioration of physical properties occur, which is not preferable.

  In addition, the acrylic fluorine-based polymer and the acrylic silicone-based polymer in the first surface treatment liquid are such that the total amount of the acrylic fluorine-based polymer and the acrylic silicone-based polymer is 2 to 30 parts by mass with respect to 100 parts by mass of the isocyanate component. It is preferable to do this. When the amount is less than 2 parts by mass, the effect of retaining carbon black or the like in the surface treatment layer is reduced. On the other hand, when the polymer amount is too large, there are problems that the electric resistance value of the charging roll is increased and the discharge characteristics are lowered, and there is a problem that an effective surface treatment layer cannot be formed due to relatively less isocyanate component.

  The second surface treatment liquid is mainly composed of an organic solvent, and is not particularly limited as long as it can remove the isocyanate component of the outermost layer penetrating into the elastic layer 12, but preferably does not contain an isocyanate component. . In addition, when it contains an isocyanate component, the thing whose density | concentration of an isocyanate component is remarkably small compared with a 1st surface treatment liquid is preferable.

  The organic solvent that can be used for the second surface treatment liquid may dissolve the isocyanate component in the same manner as the organic solvent used for the first surface treatment liquid. In terms of the process, those that do not dissolve the components and those that do not easily swell the elastic layer are preferred. Use of an organic solvent that dissolves the isocyanate component at the same level as or higher than the organic solvent of the first surface treatment liquid or a material that swells the elastic layer prevents contamination inside the elastic layer corresponding to the lower layer as well as the outermost layer. This is because there is a high risk of removing the isocyanate component for the purpose, and precise temperature control and time control are required in the process.

  What can be used suitably as an organic solvent of a 2nd surface treatment liquid by the phase-separation process mentioned above is a nonpolar solvent which is a poor solvent with respect to an isocyanate component, for example, hexane, cyclohexane, etc. are mentioned. it can. There exists an advantage that such an organic solvent and an upper layer part can be formed comparatively thinly and uniformly.

  On the other hand, when the two-step treatment is performed by another method instead of the phase separation treatment, a polar solvent that is a good solvent for the isocyanate component can be used as the second surface treatment liquid, and the organic of the first surface treatment liquid can be used. As with the solvent, ethyl acetate, methyl ethyl ketone (MEK), butyl acetate, N-methylpyrrolidone, and the like can be given. When the treatment is performed using such an organic solvent, the upper layer portion can be formed relatively thick, and the thicker the upper layer portion, the lower the hardness of the roll.

  Further, the drying and curing is not particularly limited as long as the isocyanate component can be cured inside the elastic layer, and may be a method of cooling to a temperature below the freezing point of the isocyanate component and then curing with moisture in the atmosphere. There is a method in which the solvent is volatilized under reduced pressure and then cured by heat or moisture. Generally, after drying at room temperature, heat treatment is performed as necessary. In addition, the heating temperature at this time is 40-150 degreeC, for example.

  The thickness of the upper layer portion 12b and the lower layer portion 12c is appropriately adjusted depending on the type of the organic solvent to be used, the impregnation amount of the surface treatment liquid, the concentration of the first surface treatment liquid, the temperature at which the isocyanate compound is cured.

  In the present invention, the surface treatment layer 12 a provided on the surface layer portion of the elastic layer 12 is composed of the upper layer portion 12 b and the lower layer portion 12 c as described above, and these are integrally provided on the surface layer portion of the elastic layer 12. ing. In particular, the lower layer portion 12c of the surface treatment layer 12a is integrally formed so that the isocyanate component is mainly cured and the density of the isocyanate component gradually decreases from the surface toward the inside. Is done. Therefore, bleeding of contaminants such as a plasticizer on the surface of the conductive roll can be prevented, so that the conductive roll has excellent resistance to contamination to the photoreceptor. Further, the upper layer portion 12b can suppress an increase in the hardness of the outermost layer portion, and can follow the deformation.

  The conductive rubber member according to the present invention includes, for example, a charging roll, a transfer roll, a developing roll, a toner supply roll, a cleaning used in an image forming apparatus such as an electrophotographic copying machine and printer, or a toner jet copying machine and printer. It is suitable for use in conductive rolls such as rolls, cleaning blades, transfer belts, and the like.

EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to this.
Example 1
<Manufacture of rolls>
100 parts by mass of MN-3050 (manufactured by Mitsui Takeda Chemical), a trifunctional polyether polyol, 3 parts by mass of Ketjen Black EC (manufactured by Ketjen Black International), and 5 parts by mass of Asahi # 60 (Asahi Carbon) Was added and dispersed until the particle size became 20 μm or less, and the temperature was adjusted to 80 ° C., followed by defoaming and dehydration under reduced pressure for 6 hours to obtain Liquid A. On the other hand, 10 parts by mass of Coronate C-HX (manufactured by Nippon Polyurethane) was added to and mixed with 22 parts by mass of prepolymer adiprene L100 (manufactured by Uniroyal), and the temperature was adjusted to 80 ° C. to obtain a liquid B. This A liquid and B liquid are mixed and poured into a steel pipe mold with a diameter of 23 mm preheated to 120 ° C. in which a shaft (φ: 8 mm, l: 270 mm) is arranged in the center in advance. It heated for 120 minutes and obtained the roll by which the conductive polyurethane layer was formed in the shaft surface except both ends. The surface of this roll was polished 1.5 mm, and a roll (before treatment) having an outer diameter adjusted to 20 mm was obtained.

<Preparation of surface treatment solution>
To 100 parts by mass of acetonitrile, 10 parts by mass of prepolymer adiprene L100 (manufactured by Uniroyal) was added and dissolved to prepare a surface treatment solution.

<Surface treatment of roll>
After the produced roll is immersed in the surface treatment liquid maintained at 23 ° C. for 60 seconds, 100 parts by mass of cyclohexane is gently added to the surface treatment liquid to obtain a phase separation state, pulled up at a speed of 250 mm / min, and maintained at 120 ° C. A surface treatment layer was formed by heating in an oven for 1 hour.

(Example 2)
<Manufacture of rolls>
With respect to 100 parts by mass of epichlorohydrin rubber (Epichromer CG-102; manufactured by Daiso Corporation), 0.5 parts by mass of tetraethylammonium perchlorate (manufactured by Kanto Chemical Co., Ltd.) as a conductive agent and di (2-ethylhexyl) phthalate as a plasticizer ( 3 parts by mass of DOP), 5 parts by mass of zinc oxide (ZnO), and 2 parts by mass of 2-mercaptoimidazoline (Axel-22) as a vulcanizing agent were kneaded with a roll mixer on the surface of a metal shaft having a diameter of 6 mm. A roll having an epichlorohydrin rubber layer formed on the shaft surface was obtained by press molding. The roll surface was polished to obtain a roll (before treatment) having an outer diameter adjusted to 12 mm.

<Preparation of surface treatment solution>
To 100 parts by mass of methyl isobutyl ketone, 20 parts by mass of an isocyanate compound (HDI) was added and dissolved to prepare a surface treatment liquid.

<Surface treatment of roll>
The manufactured roll was immersed in a surface treatment solution maintained at 23 ° C. for 30 seconds and then pulled up at a speed of 250 mm / min. After being in a uniform semi-dry state, immersed in butyl acetate maintained at 23 ° C. for 10 seconds. The surface treatment layer was formed by pulling up and heating in an oven maintained at 120 ° C. for 1 hour.

(Example 3)
A conductive roll of Example 3 was obtained in the same manner as in Example 1 except that the oven temperature was 150 ° C. in the surface treatment of the roll.

Example 4
A conductive roll of Example 4 was obtained in the same manner as in Example 1 except that 5 parts by mass of acetylene black was added to the surface treatment liquid.

(Comparative Example 1)
A conductive roll of Comparative Example 1 was obtained in the same manner as in Example 1 except that cyclohexane was not added.

(Comparative Example 2)
After immersing in the surface treatment solution, a conductive roll of Comparative Example 2 was obtained in the same manner as in Example 1 except that the surface of the pulled-up roll was wiped with a sponge soaked in cyclohexane without adding cyclohexane. .

(Comparative Example 3)
A conductive roll of Comparative Example 3 was obtained in the same manner as Example 2 except that it was not immersed in butyl acetate.

(Comparative Example 4)
A conductive roll of Comparative Example 4 was obtained in the same manner as in Example 2 except that the roll was immersed in the surface treatment solution and then immersed in methyl isobutyl ketone kept at 23 ° C. for 30 seconds.

(Comparative Example 5)
A urethane paint (Neolet's R-940; manufactured by Enomoto Kasei Co., Ltd.) was applied to the surface of the rubber roll of Example 2, and immersed in butyl acetate continuously maintained at 23 ° C. for 10 seconds, and then 1 in an oven maintained at 120 ° C. What formed the coating layer by heating for a time was made into the electroconductive roll of the comparative example 5.

(Test Example 1): Micro hardness measurement of roll The rubber hardness (Hs) of the conductive roll of each untreated product, the conductive roll of each example and each comparative example was measured with a micro hardness meter (MD-1: polymer meter). Measured using a product manufactured by Co., Ltd. The results are shown in Tables 1 and 2.

(Test example 2): Measurement of electrical resistance value of roll The electrical resistance value when the applied voltage was set to 100 V was measured for the conductive rolls of each untreated product, the conductive rolls of the examples and the comparative examples. The electrical resistance value was measured by applying a voltage for 30 seconds under a NN environment (23 ° C., 55% RH) with a roll placed on an electrode member made of a SUS304 plate and a load of 500 g applied to both ends of the roll. Then, the resistance value between a metal core and an electrode member was measured using ULTRAHIGH REISTANCE METER R8340A (made by Advantest Corporation). Moreover, it rotated by 45 degree | times to the circumferential direction, measured 8 places over the rotation direction, and measured the maximum value, the minimum value, and the average value at that time, respectively. The results are shown in Tables 1 and 2.

(Test example 3): Observation of surface condition About the electroconductive roll of each Example and each comparative example, the surface condition of the roll was confirmed visually. In addition, when the surface state was good, it was evaluated as ◯, when the surface state was normal, Δ, and when the surface state was poor, it was evaluated as x. The results are shown in Tables 1 and 2 below.

(Test Example 4): Image Evaluation Commercially available laser printers using the conductive rolls of Example 1 and Comparative Examples 1 and 2 as developing rolls, and the conductive rolls of Example 2 and Comparative Examples 3 to 5 as charging rolls, respectively. It was mounted on MICROLINE9600PS manufactured by Oki Data Co., Ltd., and the change in the image of the printed material after passing 10,000 sheets was visually confirmed under an NN environment (23 ° C., 55% RH). In addition, when the image was good, “◯”, when the image was normal, “Δ”, and when the image was bad, “X”. Moreover, the roll surface state at this time was confirmed visually. The results are shown in Tables 1 and 2 below.

(Test Example 5): Evaluation of re-polished product For the conductive rolls of each Example and each Comparative Example, the rubber surface was re-polished to 0.05 mm, 0.1 mm, 0.3 mm, and then the rubber hardness (Hs) was determined. In the same manner as in Test Example 1, measurement was performed again. Further, the electrical resistance value was measured again in the same manner as in Test Example 2. These results are shown in Tables 3 and 4 and FIGS.

(Summary of test results)
The conductive rolls of Examples 1, 3, and 4 that were subjected to surface treatment using the phase-separated surface treatment liquid had a microhardness and electrical resistance higher than those of Comparative Example 1 that was subjected to conventional surface treatment. It was confirmed that the value was low. In addition, it was confirmed that the conductive roll of Example 2 subjected to surface treatment in a separate process also has a lower microhardness and electrical resistance than the conductive roll of Comparative Example 3 subjected to conventional surface treatment. It was. Moreover, in the image evaluation after passing 10,000 sheets, the images of the printed materials of Examples 1 to 4 were good.

  On the other hand, the conductive roll of Comparative Example 1 subjected to the conventional surface treatment was cracked on the roll surface after passing 10,000 sheets, and the conductive roll of Comparative Example 3 was also scratched on the photoreceptor. As a result, both the printed images were unsatisfactory.

  On the other hand, the conductive roll of Comparative Example 2 in which the surface of the roll was wiped with a sponge soaked with cyclohexane after being immersed in the surface treatment solution had a microhardness and an electrical resistance value higher than those of the conductive roll of Comparative Example 1. Although it was confirmed that the electric resistance value was low, there was a large variation in the electric resistance value due to uneven wiping. Further, in the image evaluation, density unevenness was observed in the printed image, which was a failure evaluation. The conductive roll of Comparative Example 4 immersed in methyl isobutyl ketone for 30 seconds after dipping the roll in the surface treatment solution was lower in both microhardness and electrical resistance than the conductive roll of Example 2, but was not uniform. When a roll in a semi-dry state (partially left wet) is immersed again in a solvent, processing unevenness occurs on the surface, and the electric resistance value varies slightly. In the printed image, density unevenness was observed. Further, it was observed that the concentration of isocyanate in the surface treatment layer was lowered more than necessary due to immersion in methyl isobutyl ketone, which is a good solvent, or OPC contamination by a plasticizer was observed. From this, the conductive rolls of Comparative Example 2 and Comparative Example 4 are partially the upper layer part where the density of the isocyanate component is larger in the interior than the surface and the lower layer part where the density of the isocyanate component gradually decreases toward the interior. It has been found that the structure is uneven.

  On the other hand, the conductive roll of Comparative Example 5 immersed in butyl acetate for 10 seconds after the coating solution was applied to the roll was immersed again in the solvent in the semi-dried roll like the conductive roll of Comparative Example 4. As a result, unevenness of the treatment occurred on the surface, and a slight variation was observed in the electric resistance value. Further, in the image evaluation, cracks were observed on the roll surface, and the printed image was evaluated as defective.

  About the conductive roll of each Example and each comparative example, when the re-polished product was evaluated, as shown in FIGS. 2 to 5, the conductive rolls of Examples 1 to 4 have the rubber hardness of the surface layer portion, There is a region that rises from the outermost surface toward the inside, and the lower layer is a lowered region, and it was found that the surface treatment layer is composed of an upper layer portion and a lower layer portion as described above.

  As shown in FIGS. 2 and 3, in the conductive rolls of Examples 1 and 4, the rubber hardness gradually increases from the surface to a region having a thickness of about 0.1 mm, and decreases gradually in the subsequent regions. ing. In the conductive rolls of Examples 1 and 4, the electrical resistance value increases in a gradient from the surface to a region having a thickness of about 0.05 mm, and decreases in a gradient in the subsequent region to form a gradient resistance layer. It was confirmed that Similarly, in Example 2, the rubber hardness and the electrical resistance value increased in a gradient from the surface to a predetermined thickness, and decreased in a subsequent region.

  In addition, the conductive roll of Example 3 has an electrical resistance value from the surface to a region of about 0.05 mm in thickness because the base material expands by increasing the treatment temperature and the isocyanate component diffuses further to the inside. A significant increase was confirmed.

  On the other hand, the conductive rolls of Comparative Examples 1 and 3 subjected to the conventional surface treatment are inclined resistance layers in which the rubber hardness and the electrical resistance value are gradually decreased from the surface toward the inside of the rubber. Was confirmed.

  In the conductive roll of Comparative Example 4, it was confirmed that the rubber hardness and the electrical resistance value increased in a slope in a region having a thickness of about 0.1 mm from the surface.

  When the conductive roll of Comparative Example 5 was polished from the surface to a thickness of 0.05 mm, it showed rubber hardness and electrical resistance equivalent to those of the rubber base material, so that a coating layer was formed on the surface. confirmed.

It is sectional drawing of the electroconductive roll as an example of the electroconductive rubber member of this invention. It is a figure which shows the result of Test Example 5. It is a figure which shows the result of Test Example 5. It is a figure which shows the result of Test Example 5. It is a figure which shows the result of Test Example 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Conductive roll 11 Core metal 12 Elastic layer 12a Surface treatment layer 12b Upper layer part 12c Lower layer part

Claims (7)

A conductive rubber member having a surface treatment layer formed by impregnating a surface treatment liquid containing at least an isocyanate component and an organic solvent on the surface layer portion of the outermost conductive elastic layer provided with conductivity, In the upper layer portion on the surface side of the surface treatment layer, the density of the isocyanate component is larger in the interior than on the surface, and in the lower layer portion on the lower side of the upper layer portion, the density of the isocyanate component gradually decreases toward the inside. A conductive rubber member. 2. The conductive rubber member according to claim 1, wherein the surface treatment liquid further contains at least one selected from the group consisting of carbon black, an acrylic fluorine-based polymer, and an acrylic silicone-based polymer. A conductive rubber member. 3. The conductive rubber member according to claim 1, wherein the surface treatment liquid further contains a polyether-based polymer. 4. The conductive rubber member according to claim 3, wherein the polyether-based polymer has active hydrogen. 5. The conductive rubber member according to claim 4, wherein the polyether polymer is epichlorohydrin rubber. The conductive rubber member according to any one of claims 1 to 5, wherein the conductive elastic layer is provided with conductivity by at least one of an electronic conductivity imparting material and an ionic conductivity imparting material. A conductive rubber member. The conductive rubber member according to claim 1, wherein the conductive rubber member has a roll shape or a blade shape.

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