JP2002284994A - Polyimide resin composition and highly antistatic seamless belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain both a polyimide resin composition capable of dealing with a wide resistance range, having a slight dispersion of resistance, hardly causing reduction in resistance by change of an environment and with time while making the best use of high mechanical strength of a polyimide resin composition, and a highly antistatic seamless belt using the same. SOLUTION: This polyimide resin composition is characterized in that in a polyimide resin composition obtained by uniformly dispersing carbon black into a polyimide resin, a spin-lattice relaxation time (T1 ) obtained from a free induction decay curve measured by a pulse hydrogen nuclear magnetic resonance spectrum analysis at 30 deg.C is 50-300 msec. This highly antistatic seamless belt has a semielectroconductive layer composed of the polyimide resin at least on the external surface of the belt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyimide resin composition and a highly antistatic seamless belt. Such a composition and a belt are used for various industrial parts such as an electric / electronic field and office equipment.

[0002]

2. Description of the Related Art Polyimide has excellent mechanical properties, electrical insulation, heat resistance and dimensional stability.
It is widely used in various fields such as aircraft materials, electric / electronic materials, and heat-resistant fiber materials. For example, aromatic polyimide produced from pyromellitic dianhydride and 4,4'-diaminodiphenyl ether, 3,3 ', 4,4'
Aromatic polyimides produced from biphenyltetracarboxylic dianhydride and p-phenylenediamine are used in many fields as films having excellent heat resistance and mechanical properties.

[0003] In recent years, in materials for OA equipment, etc., by adding an electron conductive material such as carbon black and a metal oxide or an ion conductive material to a polyimide resin material, characteristics such as heat resistance and high strength of polyimide are obtained. While trying to make the most of the above, an attempt is made to provide an electric resistance in a semiconductive region between a medium resistance and a high resistance. However, since the metal oxide itself has a low resistance value, it is necessary to add a large amount of the metal oxide to the polyimide in order to obtain a desired electric resistance member. For this reason, the polyimide may not be able to make full use of the high mechanical strength and may exhibit brittleness. When an ion-conductive substance is used, the resistance value greatly fluctuates due to changes in the environment (particularly humidity), and thus is not suitable for use as a highly resistance-controlled member.

On the other hand, a polyimide precursor, carbon black as a conductive substance and a solvent, and a small-diameter ball are charged into a tank, forcibly stirred and mixed, and the energy of collision between the balls is used to form a polyimide resin. A seamless belt in which carbon black is dispersed is disclosed in JP-A-5-77552. However, this composition cannot be said to have sufficient dispersibility, and since the polyimide resin composition has a low viscosity, secondary aggregation of carbon black is likely to occur, whereby a conductive path is easily formed in the composition. For this reason, when the composition is used as a member such as a film, resistance variation occurs in the surface of the member. When a seamless belt using this composition is used for, for example, an electrophotographic transfer / transport member, an intermediate transfer member, and the like, there are problems in holding the transfer target, paper separation properties and transfer efficiency, It cannot meet the demand for higher speed and higher image quality of the printer. Further, in these members, the resistance was reduced due to the oxidative deterioration of the carbon black itself and the deterioration of the polyimide resin material due to repeated voltage application and the like.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to make use of the high mechanical strength of a polyimide resin composition, to be able to cope with a wide range of resistance, and to have a small variation in resistance.
An object of the present invention is to provide a polyid resin composition in which the resistance does not easily decrease due to environmental changes or aging. Another object of the present invention is to provide a highly antistatic seamless belt having good long-term paper separation properties and high transfer efficiency when used as an electrophotographic transfer / transfer member or an intermediate transfer member. is there.

[0006]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and have found that conditions for favorably dispersing carbon black as a conductive substance and the state of dispersion can be quantitatively and easily measured. Means have been found and the present invention has been completed.

That is, the present invention provides a polyimide resin composition in which carbon black is uniformly dispersed in a polyimide resin by pulsed hydrogen nuclear magnetic resonance (hereinafter abbreviated as pulsed ¹ H-NMR) spectrum analysis at 30 ° C. The spin-lattice relaxation time (T ₁ ) obtained from the free induction decay (hereinafter abbreviated as FID) curve is 50 to 300 msec.
c. It relates to the polyimide resin composition characterized by these.

Pulsed ¹ H-NMR is a method of irradiating a target with a pulsed resonance electromagnetic wave to excite nuclear spins of ¹ H protons and measuring a signal intensity and a time constant returning to a ground state after stopping the pulse wave. Yes, the molecular properties of polymer composites,
It is known as a method for evaluating crystal structure, molecular mobility, and the like. The hydrogen nucleus spin-lattice relaxation time (T ₁ ) is a time required to release the energy absorbed by the polyimide resin composition, and is a value reflecting the molecular motion of hydrogen nuclei present in the polyimide resin composition. This is a parameter indicating the uniform dispersibility of carbon black fine particles and the degree of fineness. As the carbon black particles become finer and the specific surface area increases, T ₁ becomes shorter, and in the opposite state, T ₁ becomes longer. T ₁ is 50~300msec. In the case of (1), the dispersibility of carbon black is good, and the polyimide resin composition containing the carbon black has low resistance variation and a small decrease in resistance with time. T ₁ is preferably 5
0 to 250 msec. And more preferably 50 to
200 msec. It is.

The above T ₁ is measured using a pulse nuclear magnetic resonance apparatus with a hydrogen nucleus as a measurement nucleus and a measurement frequency of 25 MHz, 90 MHz.
° pulse width 2.0 μsec. , Pulse interval 3 sec. ,
This is a value obtained by measuring FID by the inversion recovery method at a temperature of 30 ° C.

The polyimide resin composition preferably contains at least one carbon black having a volatile content of 1.0% or more.

The volatile matter (V) in the present invention is determined according to JIS
According to K 6221, the weight (W _D ) of the carbon black before heating and the weight (W _R ) of the carbon black after heating at 950 ° C. for 7 minutes were measured and calculated by the following equation.

V = (W _D -W _R ) / W _D × 100 Volatile components such as carboxyl group, quinone group, phenol group, lactone group, quinoid carbonyl group and pyrrole group present on the surface of the carbon black particles. It is known that the compound contains an oxygen-containing group, and in the present invention, the volatile content is preferably 1.0% or more, more preferably 1.5% to 20%, and still more preferably 2.0% to 2.0%. 18
% Of at least one carbon black,
Dispersibility in the polyimide resin is improved, and resistance variation is reduced.

[0013] The present invention also relates to a highly antistatic seamless belt having a semiconductive layer comprising the polyimide resin composition on at least the outer surface thereof.

The highly antistatic seamless belt has a common logarithmic value of the surface resistivity of the outer surface of 8 to 13 in order to be applied to an application requiring a function of maintaining stable semiconductivity.
(LogΩ / □), more preferably 9 to 13 (logΩ / □), and still more preferably 10 to 13 (logΩ / □).

The surface resistivity is a value measured by the method shown in the examples.

Further, in the highly antistatic seamless belt, the difference between the surface resistivity before the discharge deterioration test and the surface resistivity after the discharge deterioration test is 2. It is preferably 0 (logΩ / □) or less, more preferably 1.5 (logΩ / □) or less, and still more preferably 1.0 (logΩ / □) or less.

Here, the discharge deterioration test is a test in which the surface resistivity of the seamless belt is reduced by performing discharge treatment under the apparatus and conditions shown in the examples. The surface resistivity of the seamless belt is measured before and after the discharge deterioration test, and the difference between the obtained values is the amount of decrease in the surface resistivity (Δρs).

[Function and Effect] According to the polyimide resin composition of the present invention, T ₁ determined by pulse ¹ H-NMR spectrum analysis is within a predetermined range, and is useful as a member having uniform and stable electric resistance. Further, according to the highly antistatic seamless belt of the present invention, by being molded from the polyimide resin composition, it is used as an image forming apparatus belt such as an electrophotographic intermediate transfer belt, a transfer conveyance belt, and a transfer fixing belt. The initial characteristics such as surface resistivity can be maintained for a long period of time, and the image forming apparatus can maintain a high-quality image for a long period of time.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

The polyimide resin composition of the present invention contains carbon black as a conductive substance.

Examples of the carbon black used in the present invention include furnace black, Ketjen black,
Channel black and the like; a single type or a plurality of types of carbon blacks may be used in combination. In the present invention, it is preferable to contain at least one type of carbon black having a volatile content of 1.0% or more. Examples of such carbon black include Color Black FW manufactured by Degussa Corporation.
200, color black FW2, color black FW2
V, color black FW1, color black FW18,
Special Black 6, Color Black S170, Color Black S160, Special Black 5, Special Black 4, Special Black 4A, Printex 150T, Printex U, Printex V, Printex 140U, Printex 140V, Special Black 550, Special Black 350, Special Black 250, Special Black 100,
MA7, MA77, MA8, MA11 manufactured by Mitsubishi Chemical Corporation
MA100, MA100R, MA230, MA220,
MONARCH 700, MONARC manufactured by Cabot
H800, MONARCH 880, MONARCH 90
0, MONARCH 1000, MONARCH 130
0, MONARCH 1400, MOGUL-L, REG
AL400R, VULCAN XC-72R and the like.

The carbon black used in the present invention has an average particle size of 5 to 100 nm, preferably 10 to 70 nm.
nm. Those having an average particle diameter of less than 5 nm are substantially difficult to obtain, and have an average particle diameter of 100 nm.
This is because, when the value exceeds 3, it is difficult to obtain a practically satisfactory polyimide resin composition containing carbon black from the viewpoints of surface roughness, mechanical strength, electric resistance controllability and the like.

The average particle diameter is an average particle diameter based on a primary particle diameter measured by an electron microscope or the like. Further, the carbon black may control the electrical resistance by grafting the particle surface with a polymer such as styrene or methyl methacrylate, or by coating an insulating material, and oxidize the surface of the carbon black particles. You may.

The polyimide resin composition of the present invention can be obtained by heating the polyamic acid solution containing the carbon black to remove the solvent and perform an imide conversion reaction. Known polyimide resins can be used for the present invention, and are obtained by polymerizing an acid dianhydride and a diamine in a solvent. Among them, aromatic polyimide resins are preferable because the mechanical strength, heat resistance and dimensional stability of the obtained belt are good.

As the solvent used in the present invention, an organic polar solvent is preferable, and N, N-dialkylamides are particularly useful. For example, N, N-dimethylformamide, N, N-dimethylacetamide and the like having a low molecular weight are useful. Is mentioned. These can be easily removed from the polyamic acids and polyamic acid moldings by evaporation, displacement or diffusion. In addition, N, N
-Diethylformamide, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethylsulfoxide, hexamethylphosphortriamide, N-
Methyl-2-pyrrolidone, pyridine, tetramethylene sulfone, dimethyltetramethylene sulfone, and the like. These may be used alone or in combination. Further, the organic polar solvent cresol, phenol, phenols such as xylenol, benzonitrile, dioxane, butyrolactone, xylene,
Cyclohexane, hexane, benzene, toluene and the like can be used alone or in combination. However, in order to prevent the generated polyamic acid from being reduced in molecular weight by hydrolysis, it is preferable to avoid mixing of water during the polymerization reaction.

In the present invention, a dispersant may be further added to increase the affinity between the carbon black and the organic polar solvent. The dispersant is not particularly limited as long as it meets the purpose of the present invention, and examples thereof include a polymer dispersant. As a polymer dispersant,
Poly (N-vinyl-2-pyrrolidone), poly (N, N ')
-Diethylacrylazide), poly (N-vinylformamide), poly (N-vinylacetamide), poly (N-vinylacetamide)
-Vinylphthalamide), poly (N-vinylsuccinamide), poly (N-vinylurea), poly (N-vinylpiridone), poly (N-vinylcaprolactam), poly (N-vinyloxazoline) and the like. And one or more polymer dispersants may be added. In addition, a polymer material, a surfactant and a dispersion stabilizer against inorganic salt damage may be used within the scope of the present invention.

The acid dianhydride component includes pyromellitic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic acid Dianhydride, 2,3,3 ', 4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride Anhydrous, 1,4,5,8-
Naphthalenetetracarboxylic dianhydride, 2,2′-bis (3,4-dicarboxyphenyl) propane dianhydride,
Bis (3,4-dicarboxyphenyl) sulfone dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, ethylenetetracarboxylic Acid dianhydride;

Examples of the diamine include 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, and 3,3'-diamine.
Dichlorobenzidine, 4,4′-diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfone,
1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3′-dimethyl-
4,4'-biphenyldiamine, benzidine, 3,3 '
-Dimethylbenzidine, 3,3'-dimethoxybenzidine, 4,4'-diaminodiphenylsulfone, 4,4 '
-Diaminodiphenyl sulfide, 4,4'-diaminodiphenylpropane, 2,4-bis (β-amino-t-
Butyl) toluene, bis (p-β-amino-t-butylphenyl) ether, bis (p-β-methyl-δ-aminophenyl) benzene, bis-p- (1,1-dimethyl-5-amino-pentyl) ) Benzene, 1-isopropyl-2,4-m-phenylenediamine, m-xylylenediamine, p-xylylenediamine, di (p-aminocyclohexyl) methane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nona Methylenediamine, decamethylenediamine, diaminopropyltetramethylene, 3-methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine, 2,1
1-diaminododecane, 1,2-bis-3-aminopropoxyethane, 2,2-dimethylpropylenediamine,
3-methoxyhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 3-methylheptamethylenediamine, 5-methylnonamethylenediamine, 2,11
-Diaminododecane, 2,17-diaminoeicosadecane, 1,4-diaminocyclohexane, 1,10-diamino-1,10-dimethyldecane, 1,12-diaminooctadecane, 2,2-bis [4- (4 - aminophenoxy) phenyl] propane, piperazine, H ₂ N (CH
₂ ) ₃ O (CH ₂ ) ₂ OCH ₂ NH ₂ , H ₂ N (CH
₂ ) ₃ S (CH ₂ ) ₃ NH ₂ , H ₂ N (CH ₂ ) ₃ N
(CH ₂ ) ₂ (CH ₂ ) ₃ NH _{2 and the} like.

In order to prepare a carbon black-dispersed polyamic acid solution from these raw materials, a diamine and an acid dianhydride are dissolved in an organic polar solvent, and carbon black is added to the polyamic acid solution obtained after the polymerization reaction. After mixing and stirring, carbon black is uniformly dispersed in an organic polar solvent in advance, and a carbon black dispersion is prepared.
Among them, a method of dissolving a diamine and an acid dianhydride and performing a polymerization reaction may be mentioned. In order to make the dispersibility of carbon black uniform, the latter method of uniformly dispersing carbon black in advance is preferable.

Hereinafter, an example of the method for producing the polyimide resin composition and the highly antistatic seamless belt of the present invention will be described.

First, carbon black and a suitable polymer dispersant are added and dispersed in the organic polar solvent to prepare a carbon black dispersion.

As a dispersion method, a known method can be applied.
Ball mill, sand mill, basket mill, ultrasonic dispersion and the like can be mentioned.

Next, the acid dianhydride and the diamine are dissolved in the carbon black dispersion, mixed and stirred to allow a polymerization reaction to proceed to obtain a polyamic acid solution.

Regarding the compounding amount of each raw material, it is necessary to experimentally study a composition suitable for the intended use of the polyimide resin composition finally obtained. For example, a common logarithmic value of the surface resistivity is 8 to 13 (log Ω /
The addition amount of carbon black for obtaining the highly antistatic seamless belt of □) is preferably about 10 to 40% by weight, more preferably 13 to 30% by weight, based on the solid content of the polyimide resin. If the amount is less than 10% by weight, it is necessary to use a highly conductive carbon black in order to exhibit the above-mentioned resistance region. If such a highly conductive carbon black is added in a small amount, a stable resistance can be produced with good reproducibility. Can be difficult to do. On the other hand, if the content is more than 40% by weight, the high mechanical properties inherent in the polyimide resin are impaired, brittleness is developed, and cracks may be generated on the belt end surface when the belt is driven by a plurality of drive rollers or the like.

The monomer concentration (the concentration of the acid dianhydride component and the diamine component in the solvent) of the polyamic acid solution is set according to various conditions, but is preferably 5 to 30% by weight. Further, the polymerization reaction is carried out under a nitrogen atmosphere, the reaction temperature is preferably set to 80 ° C. or lower, and the reaction time is set to 0.1 minute.
About 5 to 10 hours are preferable. The viscosity of the polyamic acid solution can be adjusted because the solution viscosity increases as the polymerization reaction proceeds. Also, the addition of a solvent or the like
The viscosity can be adjusted by lowering the concentration.
The viscosity of the polyamic acid solution in the present invention is usually 1 to
1000 Pa · s.

The polyamic acid solution thus obtained is heated to remove the solvent and perform an imidization reaction to obtain the polyimide resin composition of the present invention.

The heating temperature for removing the solvent is not particularly limited as long as the applied solvent can be evaporated, and can be appropriately set. 230 ° C. or lower is preferable in order to prevent generation of microvoids due to rapid evaporation of the solvent in the polyamic acid solution, and is preferably 80 ° C. or higher from the viewpoint of shortening the heating time. The heating time is appropriately set according to the heating temperature, and is usually about 10 to 60 minutes.

Next, heating is performed to complete the imide conversion reaction and to remove the ring-closing water. Usually, the heating temperature at this time is from the above-mentioned solvent evaporation temperature to 450 ° C. or less, preferably 250 ° C.
４００400 ° C., heating time is 10１０〜60 minutes.

In order to form the polyimide resin composition into molded articles having various shapes, known molding methods are used. For example, in order to obtain a thin film such as a film or a belt, a film is formed by applying the polyamic acid solution to a flat plate such as a glass plate or a copper plate, an endless belt or a cylindrical mold, and then the solvent is removed by heating. By performing the imide conversion reaction and the removal of ring-closing water, a film or belt made of the polyimide resin composition can be obtained. Further, in order to obtain a seamless belt, a method in which a polyamic acid solution is cast or applied to the inner surface of a cylindrical mold and then the mold is rotated, a method in which a bullet-shaped traveling body is caused to travel by its own weight or gas pressure, or a method in which a cylindrical mold is used After dipping the mold in the polyamic acid solution, pulling it up, forming a coating by a method such as molding with a ring mold, etc., removing the solvent by heating, imide conversion reaction, and removing ring-closed water, from the polyimide resin composition To obtain a seamless belt, which can be appropriately selected.

The highly antistatic seamless belt of the present invention can be multilayered by lamination, but at least the outermost surface is made of the polyimide resin composition.

The polyimide resin composition and the highly antistatic seamless belt obtained as described above were subjected to pulse ¹ H-NMR spectrum analysis at 30 ° C. under the conditions described in the examples. Based on time vs. F
Obtain the ID curve. Next, the obtained time vs. FID curve is fitted as an exponential function type by the least squares method to obtain T ₁ .

The method for adjusting T ₁ within the above range can be adjusted by various conditions at the time of dispersion, for example, a dispersion method, a dispersion time and the like.

The polyimide resin composition of the present invention obtained as described above has a small variation in resistance value while maintaining high mechanical strength, and is unlikely to cause a decrease in resistance with time.
The polyimide resin composition of the present invention is excellent in dispersibility of the carbon black contained therein, and has a resistance value from a low resistance region corresponding to conductivity and an antistatic function to a high resistance region having functions such as charge retention. Can be controlled with less variation. Particularly in the high resistance region, the resistance generated by discharge or the like is unlikely to decrease, and the high antistatic seamless belt using the polyimide resin composition of the present invention exhibits the same function as the initial state even after long-term use. to continue.

The use of such a polyimide resin composition and a highly antistatic seamless belt is not limited to a member having functions such as antistatic property and conductivity, and a stable semiconductive material which has been difficult to control so far. It can be suitably used for applications requiring a function of maintaining the property, for example, an intermediate transfer member, a transfer transfer member, and a transfer fixing member in office equipment.

[0045]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments and the like specifically showing the configuration and effects of the present invention will be described below.

(Evaluation Method) Surface resistivity and its variation Hiresta UP, MCP-HTP16 (Mitsubishi Chemical,
Probe: UR-100) applied voltage 100V, 10
Seconds later, the surface resistivity at a measurement condition of 25 ° C. and 60% RH was examined, and the surface resistivity was represented by a common logarithmic value. Ten points were measured for each sample, and the variation of the surface resistivity was evaluated based on the variation width.

2. Spin-lattice relaxation time (T ₁ ) A glass sample tube having an outer diameter of 10 mmφ is filled with about 0.5 g of a sample obtained by finely crushing and cutting a sample, and a pulsed nuclear magnetic resonance apparatus (manufactured by JEOL Ltd., model number JNM-MU25A) ), Using a hydrogen nucleus as a measurement nucleus at a measurement frequency of 25 MHz, 9
0 ° pulse width 2.0 μsec. , Pulse interval 3se
c. The temperature was measured at 30 ° C. by the inversion recovery method.

3. Discharge deterioration test By performing corona discharge treatment on a sample to cause discharge deterioration, the same effect as the reduction in surface resistivity due to voltage concentration can be obtained. Using the corona discharge tester shown in FIG. 1, each sample obtained in the examples and comparative examples was subjected to a voltage: 70 V and a current:
3A, electrode length 0.3m, electrode-sample distance: 3m
m, sample moving speed: 0.45 m / min. The surface resistivity before and after the treatment was measured to determine the decrease in surface resistivity (Δρs).

Example 1 To 26 g of N-methyl-2-pyrrolidone (NMP) 7 was added 35 g of carbon black (volatile content 5%, average particle diameter 25 nm, 24 parts by weight based on the solid content of the polyimide resin). Thereafter, the mixture was stirred in a ball mill for 8 hours, and a carbon black-dispersed NMP solution (viscosity: 48 mP)
a · s) was obtained. Obtained carbon black dispersion NMP
118 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 43 g of p-phenylenediamine are dissolved in the solution, and the mixture is reacted while stirring at room temperature for 6 hours under a nitrogen atmosphere. And a polyamic acid solution containing carbon black (solid content 20% by weight, 23 ° C.)
, A solution viscosity of 150 Pa · s by a B-type viscometer was obtained. This polyamic acid solution is 200 mm in inner diameter and 5 mm in length.
After being supplied to the inner surface of a cylindrical mold of 00 mm and rotating at 1500 rpm for 10 minutes while applying hot air of 60 ° C. from the outer surface of the mold, the solvent was removed while gradually increasing the temperature to 120 ° C.
Dry until the coating on the inner surface of the mold itself can be supported as a coating,
Cured. After releasing this film from the mold inner surface, it is replaced with a metal pipe, the remaining solvent is removed, the ring-closing water is removed,
After heating to 360 ° C. to complete the imide conversion reaction, the mixture was cooled to room temperature to obtain a seamless belt having an average thickness of 75 μm.

Example 2 A seamless belt having an average thickness of 75 μm was prepared in the same manner as in Example 1 except that carbon black (volatile content: 1.5%, average particle diameter: 22 nm) different from that of Example 1 was used. Obtained.

Comparative Example 1 A seamless belt having an average thickness of 76 μm was prepared in the same manner as in Example 1 except that carbon black (volatile content: 0.5%, average particle diameter: 30 nm) different from that of Example 1 was used. Obtained.

Comparative Example 2 In Example 1, the amount of carbon black added was changed to 26 g (18 parts by weight based on the solid content of the polyimide resin), and the stirring time by a ball mill was set to 30.
Except that the average thickness was 75 minutes.
A μm seamless belt was obtained.

[0053]

[Table 1] From Table 1, T ₁ obtained in Examples 1 and 2 is 300 ms.
ec. The following seamless belt is not only a member having a uniform and stable surface resistivity, but also can stably maintain an initial resistance value without causing a resistance fluctuation even after a discharge deterioration test. On the other hand, T ₁ obtained in Comparative Examples 1 and 2 was 300 msec. The seamless belt that exceeds
Variations in surface resistivity occur, causing resistance fluctuations after the discharge deterioration test, and the initial resistance value cannot be stably maintained. Therefore, by determining T ₁ by pulse ¹ H-NMR, the dispersibility of carbon black can be easily controlled.

[Brief description of the drawings]

FIG. 1 is a schematic view of a discharge deterioration tester.

[Explanation of symbols]

 1 Roll 2 Sample transport direction 3 Discharge electrode

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01B 1/24 H01B 1/24 Z (72) Inventor Masahiro Uebayashi 1-1-1, Shimohozumi, Ibaraki-shi, Osaka No. 2 Nitto Denko Corporation F-term (reference) 4F100 AA37B AK49B AT00A BA02 CA21B DE01B GB51 JG01B JG03 JG04 YY00 4J002 CM041 DA036 FB266 FD116 GM01 5G301 DA18 DA51 DD10

Claims (5)

[Claims] 1. A polyimide resin composition in which carbon black is uniformly dispersed in a polyimide resin.
The spin-lattice relaxation time (T ₁ ) determined from the free induction decay curve obtained by pulsed hydrogen nuclear magnetic resonance spectroscopy analysis at 50 ° C. is 50 to 300 msec. A polyimide resin composition, characterized in that: 2. The polyimide resin composition according to claim 1, which contains at least one kind of carbon black having a volatile content of 1.0% or more. 3. A highly antistatic seamless belt having a semiconductive layer comprising the polyimide resin composition according to claim 1 on at least the outer surface thereof. 4. The highly antistatic seamless belt according to claim 3, wherein a common logarithmic value of the surface resistivity of the outer surface is 8 to 13 (logΩ / □). 5. A highly antistatic seamless according to claim 3 or 4, wherein the difference between the surface resistivity before the discharge deterioration test and the surface resistivity after the discharge deterioration test is 2.0 (log Ω / □) or less as a common logarithmic value. belt.