JP4390715B2 - Semiconductive belt and manufacturing method thereof - Google Patents

Description

  The present invention relates to an endless semiconductive belt used for a transfer belt, a conveyance belt, a photosensitive belt, and the like of an image apparatus such as an electrophotographic copying machine and a laser printer, and a manufacturing method thereof.

Conventionally, as a semiconductive belt made of a resin material, there is a belt mainly composed of a polyimide-based material, which has sufficient mechanical strength and flame retardancy, and is an electrophotographic copying machine. And a transfer belt, a conveyance belt, a photosensitive belt, and the like of an image device such as a laser printer (see, for example, Patent Document 1 or Patent Document 2).
JP 2002-351172 A JP 2003-131463 A

However, when a semiconductive belt whose main material is a polyimide-based material is used as a transfer belt, a conveyance belt, a photosensitive belt, etc. of an image apparatus, the resistance value of the semiconductive belt, in particular, as the number of printed sheets increases. surface resistivity increases, the result white spots and blurring of the image there is a problem such occurs as.

  As a solution to this problem, there is a method of adding a conductivity-imparting agent such as a conductive polymer. However, according to this method, the amount of addition becomes excessive, so that the mechanical strength of the semiconductive belt is lowered. Yes, it was not practical.

  Therefore, in order to solve the above-described problems in the prior art, the present invention provides a semiconductive belt using polyamideimide, a transfer belt for an image apparatus such as an electrophotographic copying machine or a laser printer, a conveying belt, a photosensitive belt. To provide a semiconductive belt that, when used as a belt or the like, does not easily increase in resistance value with an increase in the number of printed sheets, and can obtain a good image quality without image blanking or blurring even after long-term use. Let it be an issue.

In order to realize the above problems, the semiconductive belt according to claim 1 includes conductive carbon black containing 500 to 5000 ppm of SO ₄ ²⁻ and polyamideimide having a number average molecular weight of 30,000 to 60000. It is characterized by.

Semiconductive belt according to claim 2, in addition to the first aspect, the surface resistivity of ^{1 × 10 7 ~1 × 10 14} Ω / □ and is, and volume resistivity of 1 × 10 ⁷ to 1 × 10 ¹⁴ Ω · cm.

  The semiconductive belt according to claim 3 is characterized in that, in addition to the configuration of claim 1 or 2, the content of the conductive carbon black is in the range of 1 to 50 mass%.

  A method for producing a semiconductive belt according to claim 4 is characterized in that the semiconductive belt according to any one of claims 1 to 3 is formed by centrifugal molding.

Since this invention has the above-described configuration, according to the invention described in claim 1, conductive carbon black containing 500 to 5000 ppm of SO ₄ ²⁻ and polyamideimide having a number average molecular weight of 30000 to 60000 are obtained. Therefore, when used as a transfer belt, conveyor belt, photosensitive belt, etc. for an image apparatus such as an electrophotographic copying machine or a laser printer, the resistance value is unlikely to increase as the number of printed sheets increases. It is possible to provide a semiconductive belt capable of obtaining a good image quality without image blanking or blurring without reducing mechanical strength even when used.

According to the invention described in claim 2, the surface resistivity of ^{1 × 10 7 ~1 × 10 14} Ω / □ and is, and the volume resistivity is ^{1 × 10 7 ~1 × 10 14} Ω · cm Since the toner adhesion performance to the belt is more stable, in addition to the effect of the first aspect, the printing quality of an image apparatus such as an electrophotographic copying machine or a laser printer using the semiconductive belt according to the present invention is improved. It will be better.

According to the invention of claim 3, since the content of the conductive carbon black is in the range of 1 to 50 mass%, since so that the surface resistivity and the volume resistivity of interest can be surely obtained, In addition to the effect of claim 1 or 2, as a result, a higher quality semiconductive belt can be provided.

According to the invention described in claim 4, since the semiconductive belt according to any one of claims 1 to 3 is formed by centrifugal molding, the solution-like material is placed inside the cylindrical mold. By injecting and rotating the cylindrical mold, the solution-like material forms a resin layer with a uniform thickness on the inner wall of the cylindrical mold by the action of centrifugal force, and this resin layer is heated and cured. Thus, an endless semiconductive belt excellent in thickness accuracy, resistance value accuracy, and surface property can be obtained.

  In the present invention, known structures can be used for the structure of polyamideimide (PAI) and its synthesis. PAI is a polymer having a repeating unit in which an amide group and one or two imide groups are bonded via an organic group, and the organic group is classified into an aliphatic group and an aromatic group. In the case of an aromatic polyamideimide, an organic group to which an imide group or an amide group is bonded has a phenyl or biphenyl structure, and has a biphenyl structure with ether, carbonyl, methylene, and sulfonyl groups interposed therebetween. Specifically, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 2,2'-bis (4 '-(4 "-amino) as an organic diamine as a raw material. Phenoxy) phenyl) propane, 3,3′dimethyl-4,4′-diaminodiphenyl, etc., and trimellitic anhydride, ethylene glycol bisanhydro trimellitate, propylene glycol bisan hydrotrimellite as organic acid anhydride Tate, pyromellitic acid anhydride, benzophenone tetracarboxylic acid anhydride, 3,3 ', 4,4'-biphenyltetracarboxylic acid anhydride, etc. The actual synthesis method consists of acid component and isocyanate (amine) There are methods such as the isocyanate method or acid chloride method from Is synthesized in a solvent. However, in this invention, the structure and synthesis of PAI is not limited thereto, it is possible to optionally employ a synthesis with other known structures.

  The number average molecular weight was calculated by measuring the molecular weight in terms of polystyrene by GPC method. As the column, Shodex AD806 (manufactured by Showa Denko KK) was used, and the temperature in the column was measured at 40 ° C.

  The eluent was a 5 mM LiB NMP solution, and the flow rate was 1.0 mL / min. RI was used as a detector, polyethylene was used as a standard sample, and a measurement solution to be injected was diluted to 0.06% (w / v), and 100 μl thereof was injected.

  As the conductive filler, a carbon filler is used because it is in a region where the resistance value required for the semiconductive belt is high. As the carbon filler, carbon black such as ketjen black, acetylene black, oil furnace black, or lamp black is used. In the embodiment of the present invention, the dispersion state of carbon black plays an important role in obtaining necessary characteristics. In a normal state, carbon black hardly exists as primary particles, and is secondary particles in which primary particles are aggregated, and further, tertiary particles in which they are aggregated. This aggregate forms a conduction path of electricity, and high conductivity can be obtained with a small amount of addition as a whole. On the other hand, in the minute region, the ratio between the conduction part and the insulation part becomes large, resulting in a resistance value. It will vary greatly. In addition, the change of the resistance value is increased by the deformation to the extent of the roll, and there is a risk of adverse effects.

The content of SO ₄ ²⁻ contained in carbon black was measured by extracting a 0.5 g sample into 50 ml of ultrapure water at 95 ° C. for 16 hours, and then extracting SO ₄ ^{2− of the} extract.
The concentration was measured with an ion chromatograph (trade name: Dionex DX-120, manufactured by Nippon Diones Co., Ltd.).

In addition, as a resistance value required for a semiconductive belt used for a transfer belt, a conveyance belt, a photosensitive belt or the like of an electrophotographic copying machine or a laser printer, the surface resistance is related to the conveyance of paper or an OHP sheet. It should be in the insulating region, and the volume resistance should be in the semiconductive region for toner transfer and charge removal. And, in the case of a semiconductive belt using polyamideimide, the surface resistivity of the outer surface of the belt is in the range of 1 × 10 ⁷ to 1 × 10 ¹⁴ Ω / □ from the experiments by Examples and Comparative Examples described later. It is confirmed that the above characteristics can be achieved if the volume resistivity of the belt is in the range of 1 × 10 ⁷ to 1 × 10 ¹⁴ Ω · cm.

  In addition to the above materials, the semiconductive belt of the present invention includes appropriate additives such as a flame retardant aid, a colorant, a reaction accelerator, a reaction control agent, a reinforcing agent, an antioxidant, and an anti-aging agent. Can be added within the allowable range of the performance. A conventionally well-known additive can be used for these additives. Further, usable solvents are not particularly limited, but toluene, xylene, benzene, ethyl acetate, formamide, DMF (N, N-dimethylformamide), acetamide, NMP (N-methyl-2-pyrrolidone), N, N-dimethylacetamide, diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme), diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, dipropylene glycol methyl ether, tetramethylene glycol dimethyl ether (tetraglyme), glycols, DMSO (dimethyl sulfoxide), etc. Can be mentioned. These solvents are used alone or in combination.

  The semiconductive belt according to the present invention is obtained by uniformly mixing the above materials and heating and polymerizing and curing in a state of being molded according to a conventional method. As a method for forming a semiconductive belt, extrusion molding, centrifugal molding, casting method, etc. can be applied, but centrifugal molding is adopted because of excellent thickness accuracy, resistance accuracy, and surface properties. It is preferable to do.

  Centrifugal molding is a method of injecting a molding material made of the above-mentioned raw materials into a fluidized state into a cylindrical mold, and rotating the mold to rotate the mold on the inner wall of the mold by the action of centrifugal force. The resin layer is formed, and the resin layer is dried or heat-cured to form the resin layer inside the mold, and the cured resin layer is taken out.

The mold is preferably made of metal , the inside is mirror-finished to make the surface roughness of the semiconductive belt finer, and processed with fluororesin or silicone resin to make the semiconductive belt easy to peel off Is preferred. The outer peripheral surface of the mold may be subjected to processing such as grooves and ridges to prevent lateral blurring during centrifugal molding. Further, when a lamp heater is used as a heating method for manufacturing the semiconductive belt, it is preferable to apply a matte black heat-resistant coating to the mold in order to increase the energy absorption efficiency. The dimension of the mold is a value calculated from a desired dimension by preliminarily obtaining the magnitude of curing shrinkage and heat shrinkage of the resin material.

1 and 2 are schematic views showing a centrifugal molding apparatus used in the present invention. The centrifugal molding apparatus includes a mold 2 placed on four rotating rollers 1 and a material supply apparatus 3 for supplying a molding material into the mold 2. Ring plates 4 are provided at both ends of the mold 2 to prevent leakage of material in a fluid state and lateral blurring during the rotation of the mold. The resin solution for molding is adjusted to have a predetermined composition by the material supply device 3 and then injected into the mold 2 through the nozzle 5 by a required amount. The injection amount of the molding resin solution may be calculated from the specific gravity of the molding resin solution after solidification, the inner surface dimension of the mold, and the thickness of the product, and a predetermined amount may be injected. Since the semiconductive belt according to the present invention is required to have mechanical strength and flexibility, the thickness is adjusted to about 0.03 to 1.0 mm.

  In order to make the resin layer in the mold 2 have a uniform thickness, molding is performed while the mold 2 is rotated at the number of revolutions necessary to apply a sufficient centrifugal force to the resin solution. When the molding resin solution is injected, the mold 2 is heated by a suitable heater or the like, and the molding resin solution is dried or cured. At this time, the heating timing, temperature, and time may be appropriately selected depending on the drying and curing conditions of the molding resin solution, and the material in the mold 2 does not flow even if the rotation of the mold 2 is stopped. Later, heat treatment can be performed as a separate step.

  When drying and curing are completed, if the entire mold 2 is cooled, the semiconductive belt naturally peels from the mold 2 due to the difference in thermal expansion between the mold 2 and the semiconductive belt. The semiconductive belt peeled off from the mold 2 is cut into a predetermined size, and a semiconductive belt as a product is obtained.

  In order to omit the cutting step, it is possible to provide a weir for restricting the flow of the molding solution on the inner surface of the molding die. In addition, the obtained semiconductive belt may be provided with a meandering restricting guide member or a position detecting unit.

  EXAMPLES Hereinafter, although this invention is demonstrated about an Example, this invention is not limited to this Example.

The carbon black used was manufactured by Daicel Degussa Co., Ltd., and five grades of 350, 500, 1600, 5000, and 6000 ppm with different SO ₄ ²⁻ contents were used.

  Polyamideimide (PAI) was polymerized in N-methyl-2-polypyrrolidone (NMP) with an equal amount of trimellitic acid-anhydride and 4,4'-diphenylmethane diisocyanate while changing the reaction time. The obtained solutions were washed and dried to obtain PAI powder, and the number average molecular weights thereof were measured, and were 20000, 25000, 30000, 60000 and 68000.

  Using each PAI having a different number average molecular weight, each of the examples (Examples 1 to 4) and the comparative examples (Comparative Examples 1 to 4) having the blending amounts shown in Tables 1 and 2 (number of samples n) = 10) Each was molded to obtain semiconductive belts of Examples and Comparative Examples.

  For each of the ten semiconductive belts of Examples 1 to 4 and Comparative Examples 1 to 4, volume resistivity and surface resistivity were measured by a method in accordance with JIS K6911. “HIRESTA UP” (trade name, manufactured by Dia Instruments Co., Ltd.) was used as the measuring device, “UR-100” was used as the probe, the measurement voltage was 500 V, and the measurement time was 10 seconds. The sample was allowed to stand in an environment of 23 ° C. and 50% RH for 48 hours, then 5 points were measured in this environment, and the average value is shown in Table 1.

As a result, in Examples 1 to 4, the surface resistivity is in the range of 1 × 10 ⁷ to 1 × 10 ¹⁴ Ω / □, and the volume resistivity of the belt is 1 × 10 ⁷ to 1 × 10 ^14. It can be seen that the range is Ω · cm.

As an image test for confirming the print quality, the semiconductive belts of Examples 1 to 4 and Comparative Examples 1 to 4 are mounted on the image apparatus, and 10,000 sheets of A4 size paper are copied, The condition was observed. The image was observed visually, and if no blank portion was found on the printed paper, ◎ was marked if 1 to 10 were recognized, and × if 11 or more white spots were recognized. Further, in the printing test, the surface resistance ratio before and after the test of the semiconductive belt was calculated from the following formula.

    (Equation 1)

Surface resistance ratio = surface resistivity of the front surface resistivity / Printing test after printing test

Image test results, Examples as 1-4, the number of the semiconductive belt is molded average molecular weight of the polyamideimide 30000-60000, the ratio of the surface resistance after the test to the surface resistivity before the test 2 It was confirmed that the printing quality of the image device using these semiconductive belts was good, as small as 0.0 or less. On the other hand, in Comparative Examples 1 to 4, the ratio of the surface resistance after the printing test was as large as 4.2 or more, and white spots were observed on the printed paper.

It is a front view of the schematic diagram which shows the centrifugal molding apparatus used for this invention. It is a side view of the schematic diagram which shows the centrifugal molding apparatus used for this invention.

Explanation of symbols

1 Roller 2 Mold 3 Material supply device 4 Ring-shaped plate 5 Nozzle

Claims (4)

A semiconductive belt comprising conductive carbon black containing SO ₄ ^{2- in} an amount of 500 to 5000 ppm and a polyamideimide having a number average molecular weight of 30,000 to 60000. Surface ^{resistivity, 1 × 10 7 ~1 × 10} 14 Ω / □ and is, and the volume resistivity according to claim 1, characterized in that a ^{1 × 10 7 ~1 × 10 14} Ω · cm Semiconductive belt.   The semiconductive belt according to claim 1 or 2, wherein the content of the conductive carbon black is in the range of 1 to 50 mass%.   A method for producing a semiconductive belt, comprising molding the semiconductive belt according to any one of claims 1 to 3 by a centrifugal molding method.

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