JP2005266493A - Intermediate transfer and fixing belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intermediate transfer and fixing belt which reduces a dimension change caused by environmental variations and has improved strength. <P>SOLUTION: In the intermediate transferring and fixing including at least a polyimide resin layer containing conductive fillers, a hygroscopic expansion coefficient A(ppm/%RH) and a linear expansion coefficient B (ppm/°C) in the peripheral direction of said belt is A+2B≤60 and B≤15. It is preferable that said polyimide resin layer is formed mainly from 2,2'-dimethyl-4,4'-diamino biphenyl as a diamine component. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an intermediate transfer and fixing belt used in an electrophotographic image forming apparatus such as a copying machine, a laser beam printer, and a facsimile machine.

  In an electrophotographic image forming apparatus, generally, an electrostatic latent image corresponding to an image obtained by an image reading device is formed on the surface of a charged photoreceptor, and a toner image is formed by a developing device. The image is electrostatically transferred (primary transfer) to the intermediate transfer member, transferred again from the intermediate transfer member to paper or the like (secondary transfer), and heated and fixed by a fixing roll or a fixing belt. In recent years, technical studies have been made on an intermediate transfer and fixing belt system in which the transfer process and the fixing process are performed by a single belt, and an increase in image forming speed and an increase in image quality have been achieved.

  For example, as shown in FIG. 2, the electrostatic latent image formed on the surface of the photoreceptor roll 4 is developed with toners of various colors by developing units 7K, 7Y, 7M, and 7C, and then transferred to a toner image. The toner image is electrostatically transferred to the recording material 6 conveyed on the fixing and fixing belt 3 and conveyed to the fixing position, and the toner image is applied to the recording material 6 by heating and pressing with the heating roll 5a and the pressure roll 5b. To settle.

  In such a transfer and fixing method, since transfer and fixing can be performed with one belt, there is an advantage that the developed image formed on the surface of the photosensitive member can be faithfully transferred and fixed on a recording material as a clear image. . In addition, in the method using the transfer and fixing belt as described above, there is also a transfer and fixing method (intermediate transfer type) in which the toner image is temporarily transferred to the transfer and fixing belt and then fixed simultaneously when the toner image is transferred to a recording material. Exists.

  Conventionally, a polyimide resin belt containing a conductive filler is known as an intermediate transfer belt or a fixing belt (see, for example, Patent Documents 1 and 2). Polyimide resin is a resin that excels in heat resistance, mechanical strength, and environmental resistance. However, the intermediate transfer and fixing belt described above cannot satisfy the characteristics required for conventional intermediate transfer belt and fixing belt applications. ing. The intermediate transfer and fixing belt is not only an electrostatic transfer property (semiconductive) required as an intermediate transfer belt, an offset property (release property) required as a fixing belt and high strength, but also by repeated heating and cooling. It is also required that the dimensional change is small.

In recent years, polyimide resin films have been used as base films for flexible printed circuit boards, and polyimide resin films having a linear expansion coefficient and a hygroscopic expansion coefficient suitable for substrate applications have been developed (for example, see Patent Document 3). However, a polyimide resin belt having characteristics suitable for use as an intermediate transfer and fixing belt as described above is not known.
JP-A-63-311263 JP-A-5-77252 JP 2003-138039 A

  In the conventional intermediate transfer belt, since the influence of the hygroscopic expansion coefficient is larger than the linear expansion coefficient depending on the use environment, it is important to design a belt product that reduces the hygroscopic expansion coefficient. On the other hand, in the intermediate transfer and fixing belt, since the temperature from room temperature to about 160 ° C. is heated and cooled, the influence of the linear expansion coefficient becomes larger than the hygroscopic expansion coefficient, and product design to reduce the linear expansion coefficient is important. . Usually, when designing an apparatus, the fluctuation range of the belt circumferential length that can be absorbed by a tension roller or the like needs to be suppressed to about 2 mm for a circumferential length of about 500 mm, and to about 5 mm or less for a circumferential length of 1000 mm or more. However, if a polyimide resin having a small linear expansion coefficient is selected, the flexibility of the belt is lost and the strength is lowered.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an intermediate transfer and fixing belt that is small in dimensional change due to environmental fluctuations and excellent in strength.

  The present inventors diligently studied to solve the above-mentioned problems. As a result, they found that the above object can be achieved when the hygroscopic expansion coefficient and the linear expansion coefficient satisfy the following relationship, and the present invention has been completed.

  That is, the intermediate transfer / fixing belt of the present invention is an intermediate transfer / fixing belt having at least a polyimide resin layer containing a conductive filler, and has a hygroscopic expansion coefficient A (ppm /% RH) in the circumferential direction of the belt and The linear expansion coefficient B (ppm / ° C.) is characterized by A + 2B ≦ 60 and B ≦ 15.

  The linear expansion coefficient B represents an average linear expansion coefficient at 20 ° C. to 200 ° C., and the measurement method is described in the examples. In order to reduce the dimensional change due to heating and cooling, there is no particular limitation as long as B ≦ 15 and the relationship with A satisfies A + 2B ≦ 60, but in order to balance A and B, 6 ≦ B ≦ 12 is preferable, and 8 ≦ B ≦ 10 is more preferable.

  The hygroscopic expansion coefficient A is a value measured by the method described in Examples, and is not particularly limited as long as the relationship with B satisfies A + 2B ≦ 60, but preferably 50 ≦ A + 2B ≦ 58, 50 ≦ A + 2B ≦ 55 is more preferable.

  In order to obtain an intermediate transfer / fixing belt that satisfies the hygroscopic expansion coefficient and linear expansion coefficient and maintains the following tensile elastic modulus, the polyimide resin layer has 2,2′-dimethyl-4,4 as a diamine component. It is preferably formed with '-diaminobiphenyl as a main component. Since 2,2'-dimethyl-4,4'-diaminobiphenyl has a rigid and rigid structure, it is suitable as a raw material for a polyimide resin belt having both reduced dimensional change and high strength.

  In the intermediate transfer / fixing belt of the present invention, in order to maintain high strength while satisfying the hygroscopic expansion coefficient and linear expansion coefficient as described above, the tensile elastic modulus in the circumferential direction of the belt is preferably 5000 MPa or more. . More preferably, it is 6000-8000 MPa. The tensile elastic modulus is a value measured according to ASTM D882.

The intermediate transfer / fixing belt preferably has a toner release layer on the outer peripheral surface of the polyimide resin layer in order to perform the role as a fixing belt satisfactorily. The intermediate transfer / fixing belt has a surface resistivity of 10 ¹⁰ to 10 ¹³ Ω / □ and a volume resistivity of 10 ⁸ in order to sufficiently exhibit the electrostatic transfer properties required for the intermediate transfer belt. it is preferable that the ~10 ¹¹ Ω · cm.

The surface resistivity is more preferably 10 ¹⁰ to 10 ¹² Ω / □, and the volume resistivity is more preferably 10 ⁸ to 10 ¹⁰ Ω · cm. These characteristic values are values measured by the method described in the examples. The surface resistivity and volume resistivity can be adjusted within the above range depending on the type and content of the conductive filler.

  According to the intermediate transfer and fixing belt of the present invention, the hygroscopic expansion coefficient A and the linear expansion coefficient B satisfy a predetermined relationship, and the dimensional change is small even when used in a high humidity or high temperature environment. Even when used for a long period of time, there is little elongation of the belt, the position and tension can be easily controlled, and a high-quality and clear transfer image without color misregistration can be stably provided.

  The intermediate transfer / fixing belt of the present invention is an intermediate transfer / fixing belt having at least a polyimide resin layer containing a conductive filler, and has a hygroscopic expansion coefficient A (ppm /% RH) and linear expansion in the circumferential direction of the belt. The coefficient B (ppm / ° C.) is characterized in that A + 2B ≦ 60 and B ≦ 15.

  The method for producing the intermediate transfer / fixing belt of the present invention will be described below.

  As shown in FIG. 1, the intermediate transfer and fixing belt 3 of the present invention has a polyimide resin layer 1 containing a conductive filler. The polyimide resin layer is formed by forming a polyamic acid solution containing a conductive filler into a predetermined shape and performing an imide conversion reaction after removing the solvent. The polyamic acid solution contains polyamic acid, which is a polyimide precursor, and can be obtained, for example, by reacting approximately equimolar amounts of tetracarboxylic dianhydride and diamine in an organic solvent.

  Specific examples of the tetracarboxylic dianhydride constituting the preferable polyimide resin in the present invention include pyromellitic dianhydride (hereinafter referred to as PMDA), 3,3 ′, 4,4′-biphenyltetracarboxylic acid. Examples thereof include acid dianhydrides (hereinafter referred to as BPDA) or a mixture thereof.

  Examples of the diamine constituting the preferred polyimide resin in the present invention include aromatic diamines, specifically 2,2'-dimethyl-4,4'-diaminobiphenyl (hereinafter referred to as m-TB).

  As a composition of a polyimide resin, since a linear expansion coefficient needs to be 15 ppm / degrees C or less, it is limited to several types among many polyimide resins. Such a polyimide resin composition cannot be achieved even with a polymer composed of BPDA and p-phenylenediamine (hereinafter referred to as PDA), which is the polyimide resin having the smallest linear expansion coefficient that is commercially available. Is a polymer composed of PMDA and m-TB, or a polymer composed of a mixture of PMDA and BPDA and m-TB.

  In order to make the polyimide resin semiconductive, a conductive filler is added. As the conductive filler, metal powder such as metal such as aluminum or nickel or metal oxide compound such as tin oxide can be used in addition to carbon black. In the present invention, it is preferable to use, as the conductive filler, carbon black that can achieve the electrical characteristics described above with a small amount of use. As the carbon black, ketjen black, acetylene black or furnace black is suitably used.

  The carbon black content is preferably 5 to 30 parts by weight with respect to 100 parts by weight of polyimide (solid content). More preferably, it is in the range of 5 to 25 parts by weight. If the carbon black content is less than 5 parts by weight, the conductivity becomes too low, the volume resistivity becomes high, and the desired resistance cannot be obtained. On the other hand, if it exceeds 30 parts by weight, the resulting belt has a low mechanical strength and is liable to be cracked or cracked.

  The organic solvent used when the tetracarboxylic dianhydride and diamine are reacted has a dipole whose functional group does not react with tetracarboxylic dianhydride or diamine. It is desirable that it is inert to the system and acts as a solvent on the product polyamic acid, and acts as a solvent on at least one of the reaction components, preferably both. As a preferable organic solvent, N, N-dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone and the like are used. These may be used alone or in combination. Furthermore, phenols such as cresol, phenol and xylenol, benzonitrile, dioxane, butyrolactone, xylene, cyclohexane, hexane, benzene, toluene and the like can be mixed alone or in combination with the organic solvent. However, it is preferable to avoid the use of water in order to prevent lowering the molecular weight due to hydrolysis of the produced polyamic acid.

  In the present invention, the polyimide resin layer can further contain a heat conductive inorganic powder or the like, and inorganic powders having a known heat conduction function can be used without limitation. Specific examples include powders such as aluminum nitride, boron nitride, alumina, silicon carbide, silicon, silica, and graphite. Of these, boron nitride is preferred because it has a high thermal conductivity function, is chemically stable, and is harmless. Further, the polyimide resin layer may contain an additive such as a fluororesin powder for improving the slidability. The addition amount of these inorganic powders and fluororesin powders can be appropriately set within a range in which the mechanical strength of the obtained belt is not lowered in consideration of the addition amount of the conductive filler.

  In the present invention, as shown in FIG. 1, the toner release layer 2 can be formed on the outer peripheral surface of the polyimide resin layer 1. The toner release layer is not particularly limited, but a fluororesin or a silicone resin is suitably used. A conductive filler such as carbon black may be added to the release layer in order to adjust electric resistance. Further, for the purpose of improving the adhesion between the polyimide resin layer and the toner release layer, an intermediate layer such as a conductive adhesive layer can be formed between the layers.

  In order to form a polyimide resin layer using these raw materials, a polyamic acid solution is first prepared. As this method, a conductive filler is previously dispersed in the organic solvent, and a tetracarboxylic dianhydride and a diamine are dissolved and polymerized in the dispersion medium to obtain a polyamic acid solution. A known method such as a method of dissolving and polymerizing a dianhydride component and a diamine component to form a polyamic acid solution and adding the conductive filler to the solution can be appropriately applied. At this time, a known dispersion method can be applied, and the dispersion work is appropriately performed by a method such as a ball mill, a sand mill, or an ultrasonic dispersion.

  The monomer concentration (concentration of tetracarboxylic dianhydride and diamine in the solvent) in the polyamic acid solution is set according to various conditions, but is preferably 5 to 30% by weight. Moreover, it is preferable to set reaction temperature to 80 degrees C or less, Especially preferably, it is 5-50 degreeC, and reaction time is about 0.5 to 10 hours.

  Although the solution viscosity increases with polymerization, the viscosity in a B-type viscometer (25 ° C.) of the polyamic acid solution containing the conductive filler is preferably 1 to 1000 Pa · s, and more preferably 50 to 300 Pa · s. The solution viscosity is adjusted by lowering the monomer concentration by adding a solvent or the like.

  When the belt is an endless belt, the intermediate transfer / fixing belt can be formed by an appropriate connection method such as an adhesive method using an adhesive at the film end or a seamless belt. You can also. The seamless belt has an advantage that there is no change in thickness due to superposition, an arbitrary portion can be set as a rotation start position, and a control mechanism for the rotation start position can be omitted. Hereinafter, a method for forming a seamless belt will be described.

When forming a seamless belt, for example, an appropriate method such as a method in which a polyamic acid solution is immersed in the outer peripheral surface of a cylindrical mold, a method in which the polyamic acid solution is applied to the inner peripheral surface, a method in which centrifugation is performed, or a method in which a casting mold is filled According to the conventional method, such as a method of expanding the ring by a method, drying the formed layer into a bell-shaped shape, and heat-treating the molded product to convert the polyamic acid into an imide and recover it from the mold. It can be carried out by an appropriate method (Japanese Patent Laid-Open No. 61-95361, Japanese Patent Laid-Open No. 64-22514, Japanese Patent Laid-Open No. 3-180309, etc.). For example, a seamless belt can be formed by the following steps (1) to (3).
(1) First, a cylindrical mold is prepared as a molding mold, and a polyamic acid solution containing a conductive filler is applied to the inner peripheral surface or outer peripheral surface of the cylindrical mold. After coating, the polyimide coating layer containing conductive filler is formed by drying and curing until the coating film can at least support itself, or by heating until imide conversion is completed, and the resulting layer is cylindrical Remove from the mold.
(2) An intermediate layer such as a conductive adhesive layer may be formed on the outer peripheral surface of the polyimide resin layer by applying a primer or the like.
(3) A toner release layer mainly composed of fluororesin or silicone resin is formed on the outer peripheral surface of the formed polyimide resin layer or intermediate layer.

  In the above (1), any cylindrical mold can be used as the mold for molding as long as it is conventionally used for the production of tubular bodies, and the material has a heat resistant viewpoint. From various examples such as metal, glass and ceramics.

  As a method of applying the polyamic acid solution (containing conductive filler) to the cylindrical mold, the cylindrical mold is immersed in the polyamic acid solution to form a coating film on the outer surface, and this is formed with a cylindrical die or the like. And a method of running a traveling body (bullet shape, spherical shape) having a certain clearance with this cylindrical mold after supplying a polyamic acid solution to one end of the inner surface of the cylindrical mold, Examples include a method of rotating around an axis, supplying a polyamic acid solution to the inner surface, and forming a uniform film by centrifugal force.

  In the above-described method of traveling the traveling body, as a method of traveling the traveling body, in addition to the self-weight traveling method (a method in which the cylindrical mold is set up vertically and the traveling body travels downward by its own weight), compressed air, Examples thereof include a method using a gas explosive force and a method using a pulling wire.

  The heating temperature after applying the polyamic acid solution is not particularly limited and can be appropriately set. In particular, after heating at a low temperature of about 80 to 200 ° C. to remove the solvent, the temperature is raised to about 250 to 400 ° C. Then, a multi-stage heating method or the like for completing the imide conversion is used. Alternatively, the tubular body that can be supported by itself after low-temperature heating is peeled off to form a conductive adhesive layer or a toner release layer, and then high-temperature heating may be performed. Although the time required for heating is appropriately set according to the heating time, it is usually preferably about 20 to 60 minutes for both low temperature heating and subsequent high temperature heating. If such a multistage heating method is used, generation | occurrence | production of the microvoid in the tubular body resulting from ring-closing water and solvent evaporation which generate | occur | produce with imide conversion can be prevented.

  The polyimide resin layer thus obtained is peeled from the cylindrical mold. Examples of the method for peeling the polyimide resin layer from the cylindrical mold include a method in which air is pressure-fed into a minute through-hole provided in advance on the peripheral wall surface of the cylindrical mold end. Note that it is preferable to perform release treatment with a silicone resin or the like in advance on the inner peripheral surface of the cylindrical mold forming the polyimide resin layer, etc., which is preferable. Here, a belt composed of a single polyimide resin layer is obtained.

  In the method (2), a method for providing a conductive adhesive layer on the outer peripheral surface of the obtained polyimide resin layer is obtained by applying a primer solution, and examples thereof include roll coating, brush coating, and spray coating.

  Next, in (3), as a method of forming a toner release layer mainly composed of a fluororesin or a silicone resin, a tubular tubular body obtained by melt extrusion of the resin is applied to the outer surface of the polyimide resin layer. It is formed by a method, a method of coating the resin solution (including dispersion) on the outer surface of the polyimide resin layer, or the like. Examples of the method of coating the solution-like fluororesin solution or silicone resin solution include methods such as spray coating, spin coating, roll coating, and brush coating. As a procedure of application and heating, after applying an outer layer made of fluororesin or silicone resin to prevent voids from being generated in the outer layer, the solvent in the resin solution is removed, and then the temperature is raised above the melting point of the resin. A toner release layer made of fluorine resin or silicone resin can be formed. At this time, the imide conversion of the inner layer may be performed simultaneously.

  Carbon black is also preferably added to the toner release layer in order to adjust electric resistance. As the carbon black, ketjen black having high conductivity is suitably used, and the content thereof is within a range of 0.5 to 2.0% by weight with respect to the fluororesin or silicone resin so as to exhibit a predetermined resistance. Is preferred. Particularly preferably, it is in the range of 1.0 to 1.5% by weight. If the carbon black content is less than 0.5% by weight, the conductivity becomes too low, the surface resistivity becomes high, and the desired resistance cannot be obtained. On the contrary, the outer layer obtained in excess of 2.0% by weight is weak in mold release and wear resistance, and becomes an undesirable mold release layer.

The surface resistivity and volume resistivity of the intermediate transfer / fixing belt thus obtained are 10 ¹⁰ to 10, respectively, even in the case of a single polyimide resin layer or in the case of a polyimide resin layer and a toner release layer. It is preferable to adjust to ¹³ Ω / □ and 10 ⁸ to 10 ¹¹ Ω · cm.

  The thickness of the intermediate transfer and fixing belt of the present invention can be appropriately determined according to the purpose of use of the belt. In general, the thickness is 5 to 500 μm, especially 10 to 300 μm, especially 20 to 200 μm, in view of mechanical properties such as strength and flexibility. Among these, the thickness of the toner release layer is usually 50 μm or less, and preferably 10 to 30 μm.

[Example]
Hereinafter, examples and the like that specifically show the configuration and effects of the present invention will be described, but the present invention is not limited to these examples and the like.

[Example 1]
Dispersion was made by adding 200 g of carbon black (MA100, manufactured by Mitsubishi Chemical Corporation, furnace black, average particle diameter of 22 nm based on primary particles) to 1800 g of N-methyl-2-pyrrolidone (NMP) and stirring in a ball mill for 12 hours at room temperature. And then filtered through a # 400 stainless steel mesh to obtain a carbon black dispersion having a concentration of 10% by weight. 1327.46 g of this carbon black dispersion was transferred to a 5000 mL four-necked flask and 1,197.18 g of NMP and 2,2′-dimethyl-4,4′-diaminobiphenyl (m-TB) (manufactured by Wakayama Seika Co., Ltd.) 8 g (1.2 mol) was charged and dissolved while stirring at room temperature. Next, 261.74 g (1.2 mol) of pyromellitic dianhydride (PMDA) (manufactured by Daicel Chemical Industries) was added to the solution, reacted at 20 ° C. for 1 hour, and then heated at 75 ° C. for 20 hours. While stirring, a carbon black-containing polyamic acid solution having a solution viscosity of 150 Pa · s as measured by a B-type viscometer (solid content concentration: 20 wt%, carbon black added amount is 23 wt. Part). The carbon black-containing polyamic acid solution was filtered using a # 800 stainless steel mesh to obtain a semiconductive polyimide resin tubular body forming solution.

  Next, the tubular body forming solution is applied to the inner peripheral surface of a cylindrical cylinder having a diameter of 180 mm and a length of 500 mm so as to have a thickness of 600 μm, and is rotated at 1500 rpm for 20 minutes by a rotary molding machine to obtain a uniform thickness. A development layer was used. Next, hot air of 130 ° C. is blown from the outside of the cylindrical cylinder for 30 minutes while rotating at 250 rpm, then the temperature is raised to 390 ° C. at a rate of 2 ° C./minute, heat-cured at that temperature for 20 minutes, and then cooled. And a 76 μm semiconductive polyimide resin tubular body serving as a substrate was obtained.

  Uniformly spray-coated tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) dispersion (solid content concentration 40% by weight, 500 CL, manufactured by Mitsui Dupont Chemical Co., Ltd.) on the outer peripheral surface of the obtained polyimide resin tubular body And air dried for 10 minutes. Then, the water was evaporated and removed by heating at 100 ° C. for 10 minutes. Furthermore, PFA was sintered by heating at 400 ° C. for 10 minutes to obtain the intended semiconductive belt. The release layer had a thickness of 12 μm.

The obtained belt had a hygroscopic expansion coefficient of 33 ppm /% RH and a linear expansion coefficient of 9 ppm / ° C. The tensile elastic modulus in the circumferential direction of the belt was 7500 MPa, which was excellent in dimensional stability and strength. The belt had a surface resistivity of 2.8 × 10 ¹¹ Ω / □ and a volume resistivity of 3.1 × 10 ⁸ Ω · cm. The belt was cut to a width of 300 mm and incorporated in a laser printer as an intermediate transfer and fixing belt, and an image transfer fixing test was performed. The results are shown in Table 1.

[Example 2]
1327.46 g of the carbon black dispersion obtained in the same manner as in Example 1 was transferred to a 5000 mL four-neck flask, charged with 1197.18 g of NMP and 254.8 g (1.2 mol) of m-TB, and stirred at room temperature. And dissolved. Next, a mixture of 70.61 g (0.24 mol) of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA, manufactured by Ube Industries) and 209.40 g (0.96 mol) of PMDA was added. Then, after reacting at a temperature of 20 ° C. for 1 hour, the solution is stirred at 75 ° C. for 20 hours while being stirred, whereby a solution for forming a semiconductive polyimide resin tubular body having a solution viscosity of 160 Pa · s by a B-type viscometer (solid The component concentration was 20% by weight, and the amount of carbon black added was 23 parts by weight based on 100 parts by weight of the resin solid content.

  In the same manner as in Example 1, a semiconductive belt having a release layer was formed. The obtained belt had a hygroscopic expansion coefficient of 29 ppm /% RH and a linear expansion coefficient of 12 ppm / ° C. The tensile elastic modulus in the circumferential direction of the belt was 6500 MPa, which was excellent in dimensional stability and strength.

The belt had a surface resistivity of 3.1 × 10 ¹¹ Ω / □ and a volume resistivity of 3.2 × 10 ⁸ Ω · cm. The belt was cut to a width of 300 mm and incorporated in a laser printer as an intermediate transfer and fixing belt, and an image transfer fixing test was performed. The results are shown in Table 1.

[Comparative Example 1]
In the same manner as in Example 1 except that the composition of the polyimide resin was 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and p-phenylenediamine (PDA, manufactured by DuPont), half A conductive belt was obtained. The resulting belt had a hygroscopic expansion coefficient of 24 ppm /% RH and a linear expansion coefficient of 17 ppm / ° C. The tensile elastic modulus in the circumferential direction of the belt was 6500 MPa, which was excellent in dimensional stability and strength. The belt had a surface resistivity of 2.1 × 10 ¹¹ Ω / □ and a volume resistivity of 2.0 × 10 ⁸ Ω · cm. The belt was cut to a width of 300 mm and incorporated in a laser printer as an intermediate transfer and fixing belt, and an image transfer fixing property test was performed. The results are shown in Table 1.

[Evaluation test]
The following characteristics were examined for the semiconductive belts obtained in Examples and Comparative Examples.

(1) Surface resistivity Hiresta UP (manufactured by Mitsubishi Yuka Co., Ltd.), probe UR, applied voltage 500V,
The surface resistivity at 10 seconds was examined.

(2) Volume resistivity HIRESTA UP (manufactured by Mitsubishi Oil Chemical Co., Ltd.) was used to examine the volume resistivity of a probe UR, an applied voltage of 100 V, and a 10 second value.

(3) Hygroscopic expansion coefficient A sample conditioned for 24 hours at 30 ° C. and 15% RH was absorbed in 30 ° C. and 85% RH for 24 hours, and the length before moisture absorption (L _o ) and the length after moisture absorption. (L) is measured and the following formula:
Hygroscopic expansion coefficient (ppm /% RH) = [(L _o −L) / 70L _o ] × 1000000
Calculated from

(4) Linear expansion coefficient 20 ° C. when using a thermal analyzer (manufactured by Seiko Instruments, TMA / SS6000) and applying a load of 2 gf to a sample (width 3 mm × length 10 mm) and heating at a temperature increase of 5 ° C./min. The average coefficient of linear expansion at ˜200 ° C. was determined.

(5) Tensile Elastic Modulus According to ASTM D882, the tensile elastic modulus in the circumferential direction of the belt was measured.

(6) Image transfer and fixing property The obtained semiconductive belt was used as an intermediate transfer and fixing belt in a laser beam printer as shown in FIG. 2, and a printing test of a recording sheet made of plain paper was performed. The evaluation was good when a clear and accurate image was obtained by good transfer in all 10,000 tests, and the case where a transfer failure, an unclear image, or an inaccurate image was obtained was judged as poor.

表１より、実施例１および２の半導電性ベルトは、中間転写兼定着ベルトとして使用した場合、画像の転写定着性が良好であったのに対し、比較例１の半導電性ベルトは、１０枚目より印刷した画像に画像ムラが生じた。

From Table 1, the semiconductive belts of Examples 1 and 2 had good image transfer fixability when used as an intermediate transfer and fixing belt, whereas the semiconductive belt of Comparative Example 1 Image unevenness occurred in images printed from the 10th sheet.

Partial sectional view of the intermediate transfer and fixing belt of the present invention Example of use of intermediate transfer and fixing belt of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polyimide resin layer 2 Toner release layer 3 Intermediate transfer and fixing belt 4 Photoconductor roll 5a Heating roll 5b Pressure roll 6 Recording material 7K-7C Developer

Claims (5)

An intermediate transfer and fixing belt having at least a polyimide resin layer containing a conductive filler, wherein the hygroscopic expansion coefficient A (ppm /% RH) and the linear expansion coefficient B (ppm / ° C.) in the circumferential direction of the belt are A + 2B An intermediate transfer and fixing belt, wherein ≦ 60 and B ≦ 15. The intermediate transfer and fixing belt according to claim 1, wherein the polyimide resin layer is mainly composed of 2,2′-dimethyl-4,4′-diaminobiphenyl as a diamine component. The intermediate transfer and fixing belt according to claim 1, wherein a tensile elastic modulus in a circumferential direction of the belt is 5000 MPa or more. The intermediate transfer and fixing belt according to claim 1, further comprising a toner release layer on an outer peripheral surface of the polyimide resin layer. 5. The intermediate transfer and fixing belt according to claim 1, having a surface resistivity of 10 ¹⁰ to 10 ¹³ Ω / □ and a volume resistivity of 10 ⁸ to 10 ¹¹ Ω · cm.

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