CN101274989B - Semi-conductor polyimide film - Google Patents

Abstract

The invention provides a semiconductor polyimide film, which has a common logarithm of 9 to 15 logΩ/square at 25° C. and 60% RH surface resistivity; a common logarithm of volume resistivity of 8 to 15 logΩ·cm; according to Fatigue stress of 160 MPa or more when the number of repetitions of the fatigue test according to JIS K7118 is 107; and the number of bending resistance of the MIT test according to JIS P8115 is 2,000 times or more, and an intermediate transfer belt using the semiconductor polyimide film and conveyor belts.

Description

Semiconducting polyimide film

technical field

The present invention relates to a semiconductive polyimide film excellent in durability, particularly usable for intermediate transfer belts and conveyor belts in devices for forming and recording images by electrophotography.

Background of the invention

Due to recent improvements in image quality, speed, and compactness, devices that form and record images using electrophotographic methods such as intermediate transfer belts, conveyors in copiers, laser printers, image printers, facsimile machines, and multifunction Compared with traditional conditions such as belts, the use conditions are more stringent. In particular, due to the miniaturization of the device, the roller drums for the intermediate transfer belt and the conveyor belt are smaller, so the pressure applied to the curved part of the roller increases, and due to the high speed, the tension applied to the belt increases, thus causing the belt to elongate The factors of breakage and breakage increase, thereby increasing the demand for seamless belts excellent in durability.

As the semiconductor belt used for the intermediate transmission belt, there are hitherto known materials made of rubber material, fluorine-based material (vinylidene fluoride), polycarbonate resin material, polyimide resin material, polyamideimide resin material Semiconductor strips formed from thin films made by such as (for example, see literature 1-3).

However, such conventional belts have problems of deformation in long-term use, changes of transferred images, cracking, etc., due to recent improvements in speed, compactness, and image quality, with increased load applied to the belt during operation.

[Reference 1] JP-A-5-200904

[Reference 2] JP-A-6-228335

[Reference 3] JP-A-10-63115

Summary of the invention

An object of the present invention is to provide a semiconductive polyimide film excellent in durability, and in the case where the semiconductive polyimide film is used as an intermediate transfer belt or conveyor belt in an electrophotographic recording device, In a state where the small-diameter rollers apply stress to the belt, the belt hardly or never deforms or breaks when a load is applied to the belt during long-term operation, and there is no toner image change and transfer bleeding.

The inventors of the present invention have made extensive studies to achieve the above objects, and found that using a semiconductor polyimide film excellent in fatigue resistance and bending resistance as an intermediate transfer belt significantly reduces deformation and cracking of the belt during long-term operation, Thereby the present invention is obtained.

The semiconductor polyimide film of the present invention has: the common logarithm of the surface resistivity at 25° C. and 60% RH is 9 to 15 logΩ/square; the common logarithm of the volume resistivity is 8 to 15 logΩ·cm; fatigue is carried out according to JISK7118 The fatigue stress is 160 MPa or more when the number of test repetitions is 107; the number of bending resistance in the MIT test according to JISP8115 is 2,000 times or more. Surface resistivity, volume resistivity, fatigue stress, and number of times of bending resistance were measured by the methods described in Examples.

The semiconductive polyimide film having the above characteristics has a good balance between rigidity and rigidity, and is excellent in fatigue resistance and bending resistance. Therefore, when the semiconductive polyimide film is used as an intermediate transmission belt and conveyor belt for a long period of time, it is possible to suppress cracks and cracks due to bending stress and fatigue of the belt.

The semiconducting polyimide film of the present invention is preferably obtained from a polyamide acidic solution comprising at least one of: a copolymer comprising repeating units of: Component A, wherein tetracarboxylic acid residues are linked by imide linkages and Component B, in which the fully aromatic backbone of tetracarboxylic acid residues and the diphenyl ether of diamine residues are linked by imide bonds Skeleton; And following blend: comprise the polymkeric substance of component A as repeating unit; And comprise the polymkeric substance of component B as repeating unit, wherein the constituent molar ratio (A/B) of component A and component B is 7/3 to 3/7.

The present inventors have found that the production of a polyimide film excellent in fatigue resistance and bending resistance can be achieved by using a polyamic acid solution comprising a copolymer or a blend containing a predetermined proportion of polyimide forming a rigid skeleton. Components (component A) and components forming a flexible backbone (component B). The polyimide film of the above composition has good durability when used continuously for a long period of time as an intermediate conveyor belt or the like.

The intermediate transfer belt and conveyor belt of the present invention comprise the above-mentioned semiconductive polyimide film. The semiconductor polyimide film is excellent in fatigue resistance and bending resistance. Therefore, in the case where the semiconductive polyimide film is used as an intermediate transfer belt or conveyer belt of an electrophotographic recording device, the belt will be less deformed and broken, and can transfer a good image on a recording paper for a long time. image without causing toner image changes and transfer bleeding.

According to the present invention, a semiconductor polyimide film excellent in fatigue resistance and bending resistance can be obtained. By using the film for an intermediate transport system and a conveyance system in an apparatus for forming and recording images by electrophotography, a high-image-quality, high-speed and compact system can be provided, wherein the apparatus for forming and recording images by electrophotography is, for example, a copying machine , laser printers, image printers, fax machines and multifunction printers (MFPs).

Detailed Description of the Invention

Hereinafter, embodiments of the present invention will be described in detail.

The common logarithm of the surface resistivity of the semiconductor polyimide film of the present invention at 25° C. and 60% RH is 9 to 15 (logΩ/square), and may preferably be 10 to 12 (logΩ/square). For example, when used in an intermediate transfer belt, white spots appear when the surface resistivity is lower than 9 (logΩ/square), and transfer diffusion occurs when the surface resistivity is greater than 15 (logΩ/square).

The common logarithm of the volume resistivity of the semiconductor polyimide film is 8 to 15 (logΩ·cm), preferably 9.5 to 12 (logΩ·cm). White spots appear when the volume resistivity is lower than 8 (logΩ·cm), and transfer diffusion occurs when the volume resistivity exceeds 15 (logΩ·cm).

According to the fatigue test of JIS K7118, the fatigue stress of the semiconductor polyimide film of the present invention measured at ¹⁰⁷ repetitions is 160 MPa or greater, preferably 170 MPa or greater. When the fatigue stress is lower than 160 MPa, bending of the belt at the time of stress concentration in continuous long-term use leads to breakage or the like. The fatigue stress used here refers to the upper limit value of the stress that the belt does not break when repeated up to 10 ⁷ times in the fatigue test.

According to the MIT test of JIS P8115, the polyimide film of the present invention has a bending resistance of 2,000 times or more, and preferably 5,000 times or more. When the number of times of bending resistance is less than 2,000 times, the belt may break when stress is concentrated during continuous use.

As for the polyimide resin, it is preferable to use a polyamic acid solution comprising: a copolymer comprising repeating units of Component A and Component B; Skeleton and a p-phenylene skeleton that is a diamine residue, a fully aromatic skeleton that is a tetracarboxylic acid residue connected by an imide bond in component B and a diphenyl ether skeleton that is a diamine residue; and/or Blends of polymers comprising component A as repeating units and polymers comprising component B as repeating units.

The composition molar ratio (A/B) of component A and component B may be preferably 7/3 to 3/7, more preferably 6/4 to 4/6. When the component A having a rigid skeleton exceeds the above ratio, the bending resistance decreases although the elasticity increases due to low flexibility. When the component B with a flexible backbone exceeds the above ratio, although the flexibility and tensile properties increase, the bending resistance becomes lower than that of the copolymers and blends.

Tetracarboxylic dianhydrides are preferably used to generate fully aromatic backbones, examples of which include pyromellitic dianhydride (PMDA), 3,3',4,4'-diphenyltetracarboxylic dianhydride (BPDA), 2, 3,6,7-naphthalene tetracarboxylic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, and the like. Among them, BPDA is particularly suitable.

Also, p-phenylenediamine (PDA) is preferably used as the diamine component generating the p-phenylene skeleton. Used to produce diphenyl ether skeletons, preferably 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, etc. as diamine components, among which 4,4'-diamino Diphenyl ether (DDE).

In order to prepare the semiconductor polyimide film of the present invention, a polyamic acid solution is prepared.

Polyamic acid is prepared by a known method, such as dispersing a conductive agent into a solution, adding a catalyst to the solution, and in the dispersion solvent thus obtained, dissolving and polymerizing tetracarboxylic dianhydride and diamine in a predetermined mixing ratio; by Dissolving and polymerizing tetracarboxylic dianhydride and diamine in a solvent in a predetermined mixing ratio, and then adding a conductive agent to the solution to obtain a polyamic acid solution, etc.

In consideration of solubility and the like, the solvent used in the present invention may preferably be a polar solvent, examples of which include N,N-dialkylamides such as N,N-dimethylformamide, N,N-dimethylacetamide Amide, N,N-diethylformamide and N,N-diethylacetamide, N,N-dimethylmethoxyacetamide, dimethyl sulfoxide, hexamethylphosphoric triamide, N- Methyl-2-pyrrolidone (NMP), pyridine, dimethylsulfon (dimethylsulfon), dimethylsulfolane, and the like.

Examples of conductive agents used in the present invention include carbon black such as ketjen black and acetylene black, conductive and semiconductive powders of metals such as aluminum and nickel, tin oxide and metalloid oxide compounds, potassium titanate, etc., conductive polymers such as polyaniline and polyacetylene, etc., and these substances may be used alone or in combination of two or more, and the type is not limited. In the present invention, carbon black is preferably used alone or in combination with other conductive substances in view of the conductivity-imparting effect, uniform dispersibility, and the like.

The content of the conductive agent may be selected according to the type of the conductive agent, and may be preferably about 5 to 30 wt%, more preferably 10 to 25 wt%, based on the amount of the resin. When the content is less than 5 wt%, the uniformity of resistance decreases, sometimes resulting in a significant decrease in surface resistivity during use. When the content exceeds 30 wt%, it is difficult to obtain desired electrical resistance, and the resulting molding material becomes undesirably brittle.

A known dispersion method can be used as a method for dispersing the conductive agent, and a ball mill, a sand mill, a planetary mixer, a three-roll mill, ultrasonic dispersion, etc. can be used for the dispersion work. Furthermore, in order to obtain uniform dispersion, a dispersant such as a surfactant may be used. The dispersant is not particularly limited as long as it satisfies the object of the present invention, and examples thereof include dispersion stabilizers such as polymer dispersants, surfactants and inorganic salts, among which surfactants are preferred.

Examples of polymeric dispersants include poly(N-vinyl-2-pyrrolidone), poly(N,N'-diethylacryloyl azide), poly(N-vinylformamide), poly(N- vinylacetamide), poly(N-vinylphthalamide), poly(N-vinylamide succinate), poly(N-vinylurea), poly(N-vinylpiperidone) , poly(N-vinyl caprolactam), poly(N-vinyl oxazoline), etc., one or more polymer dispersants can be added.

Examples of surfactants include carboxylic acid type, sulfate ester type and sulfonic acid type anionic surfactants, quaternary ammonium type, aliphatic amine type and imidazoline type cationic surfactants, amine oxide type, glycine type and betaine type amphoterics Ionic surfactants, and nonionic surfactants of ether, ester, amino ether, ether ester and alkanolamide types.

In order to improve the mechanical strength and durability of the semiconductive polyimide film, a catalyst may preferably be added to the polyimide acid solution.

Examples of catalysts include tertiary amines such as trimethylamine, triethylamine, triethylenediamine, tributylamine, dimethylaniline, pyridine, 9-picoline, 6-picoline, γ-picoline, iso quinoline and lutidine, and organic bases such as 1,5-diazabicyclo[4.3.0]nonane-5,1,4-diazabicyclo[2.2.2]octane, and Among 1,8-diazabicyclo[5.4.0]undecene-7, tertiary amines are preferable in consideration of stability and easy control of imidization reaction, and isoquinoline is particularly preferable.

The amount of catalyst added may be preferably 0.04 to 0.3 molar equivalent, more preferably 0.1 to 0.2 molar equivalent, relative to 1 molar equivalent of polyamic acid in the polyamic acid solution.

The monomer concentration (tetracarboxylic dianhydride and diamine (ex. PDA+DDE) in the solvent) in the polyamic acid solution may preferably be 5% to 30%, although the concentration may vary depending on conditions. In addition, the reaction temperature during dissolution and polymerization may preferably be set to 80°C or less, more preferably 5°C to 50°C, and the reaction time may generally be 5 to 10 hours.

The polyimide film of the present invention can be obtained by heating and drying to remove the solvent of the polyamic acid solution, removing the dehydration circulating closed water, and completing the imide conversion reaction. When the polyamic acid solution is in a solution form, it is preferable to mold the polyamic acid solution in view of easy molding.

As for the seamless belt molding method, a suitable method can be adopted according to a conventional method, such as coating the polyamic acid solution on a cylinder by soaking, centrifugal molding, coating, cylindrical dice extrusion, etc. A method on the inner circumference or outer circumference of a shaped mold; wherein a casting mold is filled with a suitable method such as polyamic acid solution to obtain a ring-shaped product, the ring-shaped product is formed into a strip-shaped profile by drying, and the formed product is heated to realize polyamide Acid imide conversion, and methods of releasing molded articles from molds, etc. (JP-A-61-95361, JP-A-64-22514, JP-A-3-180309, etc.). In the molded seamless belt, appropriate treatments such as release agent treatment and defoaming treatment may be performed.

Example

Now, the present invention is illustrated in more detail with reference to Examples and Comparative Examples, but it should be construed that the present invention is not limited thereto. The evaluation items and the like in the examples were measured according to the methods described below.

Example 1

By adding 39.4 g of carbon black (Special Black4; a product of Degussa) and a nonionic surfactant (alkyldiethanolamine oxide; 0.5 wt %, relative to carbon black) to 944.7 g of N-methyl-2-pyrrolidone ( NMP) to obtain an NMP solution in which carbon black was dispersed, followed by stirring for 12 hours using a ball mill. After adding 4.3g isoquinoline to the NMP solution (0.2mol, relative to 1mol polyamic acid) of carbon black, add 146.8g BPDA, 37.8g PDA and 30.0g DDE (component A/component B=7/ 3), followed by polymerization under nitrogen atmosphere. After thickening by the polymerization reaction, the mixture was stirred at 65° C. for 7 hours to obtain a carbon-dispersed polyamic acid solution (carbon black was adjusted to 24% by weight relative to the polyimide resin component).

The polyamic acid solution thus obtained was uniformly coated on the inner surface of a cylindrical mold using round square pellets, followed by heating at 130°C for 20 minutes, and then raising the temperature to 360°C within 30 minutes to remove the remaining solvent , to remove the dehydration cycle blocking water and imidization reaction, followed by cooling to room temperature. Then, the molded product was released from the mold to obtain a seamless belt having a diameter of 100 mm, a thickness of 80 μm, and a length of 500 mm.

The tape thus obtained was cut to a width of 250 mm, and evaluated by a continuous durability test. After 240 hours of continuous operation, neither cracks nor cracks occurred in the belt, indicating that the belt has excellent durability. The surface resistivity, volume resistivity, tensile strength, tensile elasticity, fatigue stress and number of times of bending resistance of the belt were measured. The results are listed in Table 1.

Example 2

By adding 39.4 g of carbon black (Special Black4; a product of Degussa) and a nonionic surfactant (alkyldiethanolamine oxide; 0.5 wt %, relative to carbon black) to 944.7 g of N-methyl-2-pyrrolidone ( NMP) to obtain an NMP solution in which carbon black was dispersed, followed by stirring for 12 hours using a ball mill. After 4.5g isoquinoline is added to the NMP solution (0.2mol, relative to 1mol polyamic acid) of dispersing carbon black, add 146.8g BPDA, 27.0g PDA and 50.1g DDE (component A/component B=5/ 5), followed by polymerization under nitrogen atmosphere. After thickening by the polymerization reaction, the mixture was stirred at 65° C. for 7 hours to obtain a polyamic acid solution of 110 Pa·s dispersed carbon (adjusting carbon black to 23 wt % relative to the polyimide resin component). Except for the above conditions, seamless belts were obtained in the same manner as in Examples.

The tape thus obtained was cut to a width of 250 mm, and evaluated by a continuous durability test. After 240 hours of continuous operation, neither cracks nor cracks occurred in the belt, indicating that the belt has excellent durability. The surface resistivity, volume resistivity, tensile strength, tensile elasticity, fatigue stress and number of times of bending resistance of the belt were measured. The results are listed in Table 1.

Example 3

By adding 39.4 g of carbon black (Special Black4; a product of Degussa) and a nonionic surfactant (alkyldiethanolamine oxide; 0.5 wt %, relative to carbon black) to 944.7 g of N-methyl-2-pyrrolidone ( NMP) to obtain an NMP solution in which carbon black was dispersed, followed by stirring for 12 hours using a ball mill. After 4.7g isoquinoline is added to the NMP solution (0.2mol, relative to 1mol polyamic acid) of dispersing carbon black, add 146.8g BPDA, 16.2g PDA and 70.1g DDE (component A/component B=3/ 7), followed by polymerization under nitrogen atmosphere. After thickening by the polymerization reaction, the mixture was stirred at 65° C. for 7 hours to obtain a polyamic acid solution of 110 Pa·s dispersed carbon (adjusting carbon black to 19 wt % with respect to the polyimide resin component). Except for the above conditions, seamless belts were obtained in the same manner as in Examples.

The tape thus obtained was cut to a width of 250 mm, and evaluated by a continuous durability test. After 240 hours of continuous operation, neither cracks nor cracks occurred in the belt, indicating that the belt has excellent durability. The surface resistivity, volume resistivity, tensile strength, tensile elasticity, fatigue stress and number of times of bending resistance of the belt were measured. The results are listed in Table 1.

Comparative example 1

By adding 39.4 g of carbon black (Special Black4; a product of Degussa) and a nonionic surfactant (alkyldiethanolamine oxide; 0.5 wt %, relative to carbon black) to 944.7 g of N-methyl-2-pyrrolidone ( NMP) to obtain an NMP solution in which carbon black was dispersed, followed by stirring for 12 hours using a ball mill. After adding 4.0g isoquinoline to the NMP solution (0.2mol, relative to 1mol polyamic acid) of carbon black dispersed, add 146.8g BPDA and 54.0g PDA (component A/component B=10/0), then Polymerized under nitrogen atmosphere. After thickening by the polymerization reaction, the mixture was stirred at 65° C. for 7 hours to obtain a carbon-dispersed polyamic acid solution (carbon black was adjusted to 23% by weight relative to the polyimide resin component). Except for the above conditions, seamless belts were obtained in the same manner as in Examples.

The tape thus obtained was cut to a width of 250 mm, and evaluated by a continuous durability test. After about 30 hours the band ruptured. The surface resistivity, volume resistivity, tensile strength, tensile elasticity, fatigue stress and number of times of bending resistance of the belt were measured. The results are listed in Table 1.

Comparative example 2

By adding 39.4 g of carbon black (Special Black4; a product of Degussa) and a nonionic surfactant (alkyldiethanolamine oxide; 0.5 wt %, relative to carbon black) to 944.7 g of N-methyl-2-pyrrolidone ( NMP) to obtain an NMP solution in which carbon black was dispersed, followed by stirring for 12 hours using a ball mill. After adding 4.0g isoquinoline to the NMP solution (0.2mol, relative to 1mol polyamic acid) of carbon black dispersed, add 146.8g BPDA and 100.1g DDE (component A/component B=0/10), then Polymerized under nitrogen atmosphere. After thickening by the polymerization reaction, the mixture was stirred at 65° C. for 7 hours to obtain a carbon-dispersed polyamic acid solution (carbon black was adjusted to 19% by weight relative to the polyimide resin component). Except for the above conditions, seamless belts were obtained in the same manner as in Examples.

The tape thus obtained was cut to a width of 250 mm, and evaluated by a continuous durability test. The band ruptured after about 70 hours. The surface resistivity, volume resistivity, tensile strength, tensile elasticity, fatigue stress and number of times of bending resistance of the belt were measured. The results are listed in Table 1.

assessment method

1. Measuring Surface Resistivity and Volume Resistivity

Using HIRESTA UP HCP-HT450 (product of Mitsubishi Chemical Corporation, probe: UR), the surface resistivity and volume resistivity at 25°C and 60%RH were measured under the conditions of an applied voltage of 100V and a voltage application time of 10 seconds .

2. Fatigue test

A sample in the form of dumbbell No. 3 (JIS K6771 (K6301)) obtained by punching according to JIS K-7118, and controlled using a pneumatic strength tester (product of Shimadzu Corporation; SERVO PULSER EHF-F01, Model 4880) device), under the conditions of 22°C to 25°C, maximum load stress of 300MPa, minimum load stress of 30MPa, frequency of 15Hz (sinusoidal waveform) and repetitions of ¹⁰⁷ times, the fatigue stress was measured (until ¹⁰⁷ times of stress without rupture) limit).

3. MIT test

Using a test sample with a width of 15mm according to JIS P-8115, and using an MIT tester (product of Tester Sangyo Co., Ltd.), at a bending angle of 270 degrees (left and right), a bending speed of 175 times/min, and 9.8N Measured under load conditions. The number of times the test sample was subjected after the start of the test until the rupture of the test sample was determined as the number of times of resistance to bending.

4. Measuring Tensile Strength and Tensile Elasticity

According to JIS K6771 (K6301), measurement is performed using a tape test sample in the form of dumbbell No. 3 obtained by punching.

5. Continuous durability test

The resulting semiconducting polyimide tape was cut to a width of 250 mm and fixed on a rotating device with a roll diameter of 10 mm at a roll speed of 10 m/min and a tape tension of 2 kg/250 mm. Continuous operation was performed for 240 hours to evaluate belt breakage.

As shown in Table 1, each of the belts in Examples 1 to 3 in which the compositional molar ratio of Component A and Component B was within a predetermined range had no cracks and cracks after 240 hours of continuous operation, indicating excellent durability. In contrast, each of the belts in Comparative Examples 1 and 2 in which the compositional molar ratio of Component A and Component B was out of the predetermined range ruptured after several tens of hours of continuous operation.

Although it has been described in detail with reference to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope thereof.

This application is based on Japanese Patent Application No. 2005-281865 filed on September 28, 2005, the entire contents of which are incorporated herein by reference.

Claims (3)

1. semi-conductor polyimide film has:

25 ℃ of denary logarithm with 60%RH lower surface resistivity be 9 to 15log Ω/square;

The denary logarithm of volume specific resistance is 8 to 15log Ω cm;

Carrying out the fatigue test multiplicity according to JIS K7118 is 10 ⁷The time, fatigue stress is more than the 160MPa; With

The anti-number of bends that carries out the MIT test according to JIS P8115 is more than 2,000 times,

Said semi-conductor polyimide film can obtain from the polyamic acid solution that comprises at least a following material:

The multipolymer that comprises following repeating unit:

Component A wherein connects complete fragrant skeleton by imide bond and to the phenylene skeleton, described complete fragrant skeleton is the tetracarboxylic acid residue, and described is the diamines residue to the phenylene skeleton; With

B component wherein connects complete fragrant skeleton and diphenyl ether skeleton by imide bond, and described complete fragrant skeleton is the tetracarboxylic acid residue, and described phenyl ether skeleton is the diamines residue; With

The blend of following material: comprise the polymkeric substance of component A as repeating unit; With comprise the polymkeric substance of B component as repeating unit,

Wherein the constitutive molar ratio of component A and B component (A/B) is 3/7 to＜5/5.

2. an intermediate transfer belt comprises the described semi-conductor polyimide film of claim 1.

3. a conveying belt comprises the described semi-conductor polyimide film of claim 1.