JP2011191500A - Method for manufacturing semiconductive belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductive belt having desired semiconductive properties (e.g., surface resistivity, volume resistivity) by a simple operation. <P>SOLUTION: The method for manufacturing the semiconductive belt includes steps for using a semiconductive resin composition containing a polyamide resin, oxidation-treated carbon black and an amine compound having a pKa of &ge;7, and heating the composition where the surface resistivity and the volume resistivity of the belt are adjusted by compounding. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method for manufacturing a semiconductive belt.

  As an image forming apparatus for forming and recording an image by an electrophotographic method, a copying machine, a laser printer, a video printer, a facsimile, a complex machine of these, and the like are known. In this type of device, the image on the image carrier such as a photosensitive drum is temporarily transferred to the intermediate transfer belt (primary transfer) and then transferred onto the printing sheet (secondary transfer) for the purpose of improving the life of the device. Then, an intermediate transfer method in which fixing is performed has been studied. In addition, a transfer system that also transfers the sheet while transferring it to the printing sheet has been studied.

  The semiconductive belt used for the intermediate transfer belt or the like is typically formed from a resin composition containing carbon black as a conductive filler. When normal carbon black is used as the carbon black, there is a problem that secondary aggregation tends to occur. Therefore, oxidized carbon black (oxidized carbon black) that can be excellent in dispersibility is also used (see, for example, Patent Document 1).

  However, depending on the combination of the resin and carbon black used, the intended semiconductivity may not be obtained even if the amount of carbon black added is increased.

JP 2002-341673 A

  The present invention has been made in order to solve the above-described conventional problems. The main object of the present invention is to provide a semiconductive belt having desired semiconductivity (for example, surface resistivity, volume resistivity) by a simple operation. It is in providing the method of manufacturing.

The method for producing a semiconductive belt of the present invention uses a semiconductive resin composition containing a polyamideimide resin, oxidized carbon black, and an amine compound having a pKa of 7 or more.
In a preferred embodiment, the amine compound has a pKa of 10 or less.
In a preferred embodiment, the melting point of the amine compound is higher than 75 ° C.
In a preferred embodiment, the amine compound is imidazole.
In a preferred embodiment, the method includes a step of supplying the semiconductive resin composition into a cylindrical mold to form a coating film on the inner surface of the mold, and a step of performing a heat treatment. It is performed in stages, and the first heat treatment is performed by applying hot air from the outside of the mold.
In a preferred embodiment, the melting point of the amine compound is higher than the initial heat treatment temperature.
In a preferred embodiment, the initial heat treatment temperature is 75 to 85 ° C.
According to another aspect of the present invention, a semiconductive belt is provided. This semiconductive belt is manufactured by the above manufacturing method.
In a preferred embodiment, it includes a semiconductive layer having a surface resistivity of 1 × 10 ¹⁰ to 1 × 10 ¹⁴ Ω / □.
In a preferred embodiment, it includes a semiconductive layer having a volume resistivity of 1 × 10 ⁹ to 1 × 10 ¹³ Ω · cm.

  According to the method for producing a semiconductive belt of the present invention, a semiconductive belt having a desired semiconductivity (for example, surface resistivity, volume resistivity) can be easily produced by using an amine compound. . Specifically, when an amidoimide-based resin and an oxidized carbon black are combined, the desired semiconductive region may not be reached even if the amount of carbon black added is adjusted. This is considered to be one of the factors that the dispersibility of carbon black is high and a conductive path is not formed. By adding an amine compound, the surface state of the oxidized carbon black can be changed, and the carbon black can be aggregated to form a conductive path. As a result, the semiconductivity of the resulting belt can be changed. Therefore, the semiconductivity of the resulting belt can be controlled by adjusting the addition amount of the amine compound.

It is a graph which shows the relationship between the addition amount of an amine compound, and surface resistivity. It is a graph which shows the relationship between the addition amount of an amine compound, and volume resistivity.

Hereinafter, although preferable embodiment of this invention is described, this invention is not limited to these embodiment.
A. Manufacturing Method The manufacturing method of the semiconductive belt of the present invention uses a semiconductive resin composition containing a polyamideimide resin, oxidized carbon black, and an amine compound having a pKa of 7 or more.

A-1. Semiconductive resin composition The semiconductive resin composition of the present invention comprises a polyamideimide resin, an oxidized carbon black, and an amine compound. The polyamideimide-based resin typically includes a repeating unit in which an amide group and one or two imide groups are bonded via an organic group. Depending on the structure of the organic group, for example, it is classified into an aromatic polyamideimide and an aliphatic polyamideimide.

  The polyamide-imide resin can be produced, for example, by polycondensing an acid component and a diamine or diisocyanate by any appropriate method. Specifically, the acid component and the diamine or diisocyanate are brought to a predetermined temperature (usually about 60 to 200 ° C.) in a polar solvent such as N, N′-dimethylacetamide or N-methyl-2-pyrrolidone (NMP). It can be produced by stirring while heating.

  Examples of the acid component include trimellitic acid, trimellitic anhydride or acid chloride, benzene-1,2,4,5-tetracarboxylic acid (pyromellitic acid), biphenyltetracarboxylic acid, biphenylsulfone. Tetracarboxylic acid, benzophenone tetracarboxylic acid, biphenyl ether tetracarboxylic acid, tetracarboxylic acid such as ethylene glycol bistrimellitate, propylene glycol bistrimellitate and their anhydrides, oxalic acid, adipic acid, malonic acid, sebacic acid, azelain Aliphatic dicarboxylic acids such as acid, dodecanedicarboxylic acid, dicarboxypolybutadiene, dicarboxypoly (acrylonitrile-butadiene), dicarboxypoly (styrene-butadiene); 1,4-cyclohexanedicarboxylic acid, 1,3-cycl Alicyclic dicarboxylic acids such as hexanedicarboxylic acid, 4,4'-dicyclohexylmethanedicarboxylic acid, dimer acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, diphenylsulfone dicarboxylic acid, diphenyl ether dicarboxylic acid, naphthalenedicarboxylic acid, etc. Can be mentioned. These can be used alone or in combination of two or more.

  Examples of the diamine or diisocyanate include aliphatic diamines such as ethylenediamine, propylenediamine, and hexamethylenediamine, and diisocyanates thereof, 1,4-cyclohexanediamine, 1,3-cyclohexanediamine, isophoronediamine, 4,4′- Alicyclic diamines such as dicyclohexylmethane diamine and diisocyanates thereof, m-phenylene diamine, p-phenylene diamine, 4,4'-diaminodiphenyl methane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, Aromatic diamines such as benzidine, o-tolidine, 2,4-tolylenediamine, 2,6-tolylenediamine, xylylenediamine, and their diisocyanates, and 1,5′-diisocyanate Diisocyanato naphthalene, 4,4'-diisocyanato-3,3'-dimethyl biphenyl, and the like. These can be used alone or in combination of two or more.

  A commercially available product can be used as the polyamideimide resin. For example, Hitachi Chemical Co., Ltd. HPC series, Toyobo Co., Ltd. Bilomax etc. are mentioned.

  The concentration of the polyamideimide resin in the semiconductive resin composition is preferably 10 to 40% by weight, more preferably 10 to 35% by weight.

  The oxidized carbon black has an acidic functional group on its surface. Examples of the acidic functional group include a carboxyl group, a lactone group, a phenolic hydroxyl group, and a quinone group. The average primary particle size of the oxidized carbon black is preferably 5 to 100 nm, more preferably 10 to 50 nm.

  Oxidized carbon black can be produced, for example, by subjecting carbon black to oxidation treatment. As the oxidation treatment, for example, an air oxidation method in which contact and reaction with air is performed in a high temperature atmosphere, a method of reaction with nitrogen oxide or ozone at room temperature, a method of air oxidation at high temperature and then ozone oxidation at low temperature Etc.

  A commercially available product can be used as the oxidized carbon black. For example, SPECIAL BLACK4 (manufactured by Degussa), SPECIAL BLACK250 (manufactured by Degussa), BLACK PEARLS L (manufactured by Cabot), and the like can be mentioned.

  The content of the oxidized carbon black is preferably 10 to 40 parts by weight, more preferably 15 to 35 parts by weight with respect to 100 parts by weight of the polyamideimide resin (solid content).

  As described above, the semiconductive resin composition of the present invention contains an amine compound. The amine compound preferably has a pKa of 7 or more. Here, “pKa” is a dissociation constant of a conjugate acid of an amine compound, and is a value obtained at a temperature of 25 ° C. and in an aqueous solution state. By using such an amine compound of pKa, a semiconductive belt having desired semiconductivity (for example, surface resistivity, volume resistivity) can be easily produced. Specifically, by containing an amine compound, the surface state of the oxidized carbon black can be changed, and the carbon black can be aggregated to form a conductive path. As a result, the semiconductivity of the resulting belt can be changed. Therefore, the semiconductivity of the resulting belt can be controlled by adjusting the amine compound content without changing the carbon black content.

  The maximum value of pKa of the amine compound is 14, preferably 10 or less, more preferably 9 or less, still more preferably 8 or less, and particularly preferably 7.5 or less. By using such an amine compound of pKa, control for obtaining desired semiconductivity can be easily performed. Specifically, if the value of pKa is too large, a rapid change in resistivity tends to occur with a small amount, which may make it difficult to control the resistivity.

  The melting point of the amine compound is preferably higher than the initial drying temperature described later. Specifically, it is preferably higher than 75 ° C. By using such an amine compound, desired semiconductivity can be obtained satisfactorily. Specifically, carbon black can be well aggregated while the semiconductive resin composition has fluidity. On the other hand, if the melting point of the amine compound is lower than the initial drying temperature, the amine compound may be removed as the solvent is dried. As a result, there is a possibility that the dispersion of the resistivity is caused, for example, the aggregation of the carbon black is not induced, or the resistivity obtained by the drying condition is greatly changed.

  As the amine compound, any appropriate compound that can satisfy the above pKa can be used. The type of amine compound may be a tertiary amine, a secondary amine, or a primary amine. Specific examples include imidazole derivatives such as imidazole and 2-methylimidazole; pyridine derivatives such as 4-aminopyridine and 4-dimethylaminopyridine; and aliphatic amines such as 2-aminoethanol and triethylamine. These can be used alone or in combination of two or more. Among these, imidazole is preferable.

  The content of the amine compound is set to any appropriate value depending on the target semiconductive region, the type of amine compound used, and the like. The amount is typically 0.002 to 0.03 mol with respect to 100 g of polyamideimide resin (solid content). For example, when imidazole is used as the amine compound, the amount is preferably 0.01 to 0.3 mol.

  The semiconductive resin composition can contain any appropriate additive depending on the purpose and the like. Examples of the additive include a slidable filler, a heat conductive filler, a heat insulating filler, and an abrasion resistant filler.

  Examples of the solvent used in the semiconductive resin composition include aprotic polar solvents such as N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF), and dimethylsulfoxide (DMSO). And a mixture of xylene, toluene and the aprotic polar solvent. Among these, N-methyl-2-pyrrolidone (NMP) and dimethylacetamide (DMAc) are preferable.

  Arbitrary appropriate methods are employ | adopted as a preparation method of a semiconductive resin composition. In one embodiment, the carbon black is added and dispersed in a solution obtained by dissolving the polyamideimide resin in a solvent in advance, and then the amine compound is added. For dispersion of carbon black, for example, a bead mill, a roll mill, a planetary mixer or the like is used.

A-2. Molding The semiconductive belt is preferably produced by supplying the semiconductive resin composition into a cylindrical mold to form a coating film on the inner surface of the mold, and then performing a heat treatment.

  Arbitrary appropriate methods are employ | adopted as a formation method of the said coating film. For example, a method of supplying a semiconductive resin composition into a rotating mold and forming a uniform coating film by centrifugal force, inserting a nozzle along the inner surface of the mold, and semiconductive in the rotating mold A method in which the resin composition is discharged from a nozzle and applied in a spiral manner while the nozzle or the mold is running, and a traveling body (bullet) having a certain clearance between the mold and the spiral coating is performed roughly. Shape, spherical shape), a method in which a mold is immersed in a semiconductive resin composition to form a coating film on the inner surface, and then a film is formed with a cylindrical die, etc. Examples thereof include a method of running a traveling body (bullet shape, spherical shape) having a certain clearance with a mold after supplying the conductive resin composition.

  The thickness of the coating film formed of the semiconductive resin composition is preferably 70 to 2000 μm, more preferably 100 to 1000 μm.

  The conditions for the heat treatment are set to any appropriate conditions. Preferably, the heat treatment is performed in two stages. By performing the heat treatment in two stages, a semiconductive belt having no defects on the surface can be obtained. The first heat treatment (initial drying) is preferably performed to such an extent that the fluidity of the coating film formed on the inner surface of the mold can be lost. In a preferred embodiment, the initial drying is performed by applying hot air from the outside of the mold. By applying hot air, a semiconductive belt having no defects on the surface can be obtained. The initial drying temperature is preferably 75 to 85 ° C. The heating time is preferably 10 to 60 minutes. The heating temperature of the second heat treatment is preferably 150 to 300 ° C. The heating time is preferably 10 to 60 minutes.

B. Semiconductive belt The semiconductive belt obtained by the above production method may include layers other than the layer (semiconductive layer) formed of the semiconductive resin composition. The surface resistivity (ρs) of the semiconductive layer is preferably 1 × 10 ¹⁰ to 1 × 10 ¹⁴ Ω / □. The volume resistivity (ρv) is preferably 1 × 10 ⁹ to 1 × 10 ¹³ Ω · cm.

  The thickness of the semiconductive layer is typically 30 to 200 μm, preferably 50 to 100 μm.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples.

[Example 1]
(Preparation of resin composition)
To polyamideimide varnish (manufactured by Hitachi Chemical Co., Ltd., trade name: HPC-7200), oxidation-treated carbon black (manufactured by Degussa, trade name: Special Black 4) was added in an amount of 25 parts by weight based on 100 parts by weight of the resin solid content. Pre-dispersion was performed with a mechanical stirrer with a stirring blade, and main dispersion was performed with a bead mill or a roll mill.
A predetermined amount of imidazole (pKa: 7.04, melting point: 90 ° C.) is added to 100 g of resin solids in a varnish in which carbon black is dispersed, and the mixture is stirred for 2 hours with a mechanical stirrer and allowed to stand overnight for defoaming. I put it.

(Molding)
The resin composition was applied to the inner surface of a cylindrical mold (made of SUS) having an inner diameter of 300 mm and a length of 900 mm with a dispenser, and then the mold was rotated at 1500 rpm for 10 minutes to form a uniform coating film.
Next, as initial drying, hot air of 80 ° C. was applied for 30 minutes from the outside of the mold while rotating the mold at 20 rpm. Thereafter, the temperature was raised to 200 ° C. and held for 30 minutes, then cooled, and the belt was released from the mold to obtain a semiconductive belt having a thickness of 80 μm.

[Example 2]
A semiconductive belt was obtained in the same manner as in Example 1 except that 2-methylimidazole (pKa: 7.56, melting point: 140 to 145 ° C.) was used instead of imidazole.

[Example 3]
A semiconductive belt was obtained in the same manner as in Example 1 except that 4-aminopyridine (pKa: 9.26, melting point: 158 ° C) was used instead of imidazole.

[Example 4]
A semiconductive belt was obtained in the same manner as in Example 1 except that 2-aminoethanol (pKa: 9.64, melting point: 10.5 ° C.) was used instead of imidazole.

[Example 5]
A semiconductive belt was obtained in the same manner as in Example 1 except that 4-dimethylaminopyridine (pKa: 9.68, melting point: 110 to 114 ° C.) was used instead of imidazole.

[Example 6]
A semiconductive belt was obtained in the same manner as in Example 1 except that triethylamine (pKa: 10.68, melting point: -114.7 ° C.) was used instead of imidazole.

[Comparative Example 1]
In preparing the resin composition, a semiconductive belt was obtained in the same manner as in Example 1 except that imidazole was not added.

[Comparative Example 2]
A semiconductive belt was obtained in the same manner as in Comparative Example 1 except that 30 parts by weight of oxidized carbon black was added to 100 parts by weight of the resin solid content.

[Comparative Example 3]
A semiconductive belt was obtained in the same manner as in Example 1 except that isoquinoline (pKa: 5.14, melting point: 26 to 28 ° C.) was used instead of imidazole.

[Comparative Example 4]
A semiconductive belt was obtained in the same manner as in Example 1 except that 2-phenylimidazole (pKa: 6.5, melting point: 146 ° C.) was used instead of imidazole.

<Evaluation>
The surface resistivity (ρs) and volume resistivity (ρv) of the obtained semiconductive belt were measured by the following methods. The measurement results are shown in Table 1 as common logarithmic values. 1 and 2 plot the values in Table 1 with the horizontal axis representing the amount of amine compound added and the vertical axis representing the resistivity. In Table 1, when the logarithm of resistivity is 14.5 or more, “over” is indicated, and when the logarithm of resistivity is 6.5 or less, “under” is indicated. In FIG. 1 and FIG. 2, for convenience, “over” is represented as 14.5, and “under” is represented as 6.5.

(Method for measuring surface resistivity and volume resistivity)
Using Hiresta UP MCP-HTP16 (manufactured by Mitsubishi Chemical Analytech Co., Ltd., probe: URS) under conditions of 25 ° C. and 60% RH, surface resistivity (applied voltage 500 V, after 10 seconds) and volume resistivity (applied) Voltage 100V, 10 seconds later) was measured.

As shown in Table 1, in Examples 1 to 6, the resistivity decreases as the amount of amine compound added increases. On the other hand, in Comparative Examples 1 and 2 in which no amine compound was added, the resistivity remained high even when the amount of oxidation-treated carbon black was changed. Further, in Comparative Examples 3 and 4 using an amine compound having a low pKa value, the resistivity remained high even when the amine compound was added.
As shown in FIG. 1 and FIG. 2, when Examples 1 to 6 are compared, it can be said that the decrease in resistivity tends to be remarkable when the value of pKa is large. In addition, Examples 4 and 6 using an amine compound that was liquid at the time of initial drying were out of this tendency.

  The semiconductive belt obtained by the present invention can be suitably used, for example, as an intermediate transfer belt or a transfer conveyance belt of an image forming apparatus that forms and records an image by an electrophotographic method.

Claims (10)

  A method for producing a semiconductive belt, comprising using a semiconductive resin composition comprising a polyamideimide resin, oxidized carbon black, and an amine compound having a pKa of 7 or more.   The method for producing a semiconductive belt according to claim 1, wherein the amine compound has a pKa of 10 or less.   The manufacturing method of the semiconductive belt of Claim 1 or 2 whose melting | fusing point of the said amine compound is higher than 75 degreeC.   The method for producing a semiconductive belt according to claim 1, wherein the amine compound is imidazole. Supplying the semiconductive resin composition into a cylindrical mold, forming a coating film on the inner surface of the mold, and performing a heat treatment;
The method for producing a semiconductive belt according to any one of claims 1 to 4, wherein the heat treatment is performed in two stages, and the first heat treatment is performed by applying hot air from the outside of the mold.   The method for producing a semiconductive belt according to claim 5, wherein the melting point of the amine compound is higher than the first heat treatment temperature.   The method for producing a semiconductive belt according to claim 5 or 6, wherein the initial heat treatment temperature is 75 to 85 ° C.   A semiconductive belt manufactured by the manufacturing method according to claim 1. The semiconductive belt according to claim 8, comprising a semiconductive layer having a surface resistivity of 1 × 10 ¹⁰ to 1 × 10 ¹⁴ Ω / □. The semiconductive belt according to claim 8 or 9, comprising a semiconductive layer having a volume resistivity of 1 × 10 ⁹ to 1 × 10 ¹³ Ω · cm.

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