JP2001277264A - Polyimide seamless tube and method for preparing it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyimide seamless tube in which degree of orientation of the molecular chain in the longer direction and in the peripheral direction is low and anisotropic properties are not substantially exhibited and which has high elastic moduli and has a low water absorption and a method for preparing it. SOLUTION: The polyimide seamless tube comprising a polyimide shown by general formula (1) (wherein n is an integer of 1-20) and having a tensile elastic modulus in the longer direction of at least 480 kg/mm2 is provided. The method for preparing the polyimide seamless tube wherein a polyimide precursor solution in which a polyimide precursor to be changed to the polyimide shown in the above described general formula (l) is dissolved as a solute in a solvent is molded to imidize the polyimide precursor, is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention has a high elastic modulus,
The present invention relates to a polyimide seamless tube having a low water absorption and a method for producing the same.

[0002]

2. Description of the Related Art Due to its excellent heat resistance, friction resistance, abrasion resistance and mechanical properties, wholly aromatic polyimides are one of engineering plastics whose demand has been increasing in various industrial fields in recent years. In particular, in the OA equipment industry, it is used for various members because of its excellent heat resistance and wear resistance, and its application range is rapidly expanding.

In particular, in a thermal fixing unit of a printer or a copying machine, a conventionally used rubber-coated metallic cylindrical heater consumes a large amount of power, and therefore has a small linear heater using a polyimide seamless tube. Research and development are progressing rapidly. The heat fixing unit is supported and driven from the inside by a plurality of rotating bodies, and its end is suppressed by a bearing in order to suppress the displacement due to the meandering of the tube.

[0004]

However, in general, polymer seamless tubes are inferior in mechanical properties as compared with metal seamless tubes, and when the displacement is extremely advanced, the ends in contact with the bearings are turned up. There was a problem that normal operation could not be performed due to return or bending.
Particularly in a high-speed model, the number of sheets printed and copied in a certain period is likely to be larger than that in a normal model, and even a slight displacement of the supporting / driving roller causes the above problem in a short time. In order to avoid this, maintenance has to be performed every short period, and there has been a problem that the maintenance cost is extremely high.

As means for solving this problem, Japanese Patent Application Laid-Open
JP-83122 discloses that a polyimide seamless tube having an elastic modulus of 350 kg / mm ² or more is used. However, when the speed is increased, meandering to one side during a unit period is large, and For stable use during the period, one having a higher elastic modulus in the longitudinal direction is required. Japanese Patent Application Laid-Open No. 8-80580 discloses that the elastic modulus is 70%.
Although a 0 kg / mm ² seamless tube is shown, the inorganic particles contained therein are insulators, so they are charged when applied to OA equipment and adhere to toner when used in printers and copiers. In addition, the stamp image is disturbed, and it is necessary to prepare raw materials separately because it is a blend,
There was a problem that it became expensive in terms of cost.

In order to improve the absolute value of the withstand load, a certain thickness or more is required. In general, a polyimide film-shaped molded article has a problem that the elastic modulus decreases as the thickness increases. Was. Also, due to climate change,
When the humidity rises, there is a concern that the fixing tube absorbs moisture in the atmosphere and the dimensions change. Such a dimensional change causes a deviation during rotation of the tube. In addition, polyimide seamless tubes are often molded using a cylindrical mold as disclosed in JP-A-6-23770, but polyimide molded articles are generally formed by molding the precursor and imidizing the precursor. And a large shrinkage occurs during the imidization process. When molded using a cylindrical mold, the polyimide molecules tend to be oriented in the longitudinal direction, and often exhibit a larger elastic modulus in the longitudinal direction than in the circumferential direction. As a result, there is a tendency for a phenomenon in which sufficient mechanical properties are obtained in the longitudinal direction, but insufficient in the circumferential direction.

In view of the above circumstances, an object of the present invention is to reduce the degree of molecular chain orientation in the longitudinal and circumferential directions, exhibit substantially no anisotropy, and achieve a high elastic modulus in the longitudinal and circumferential directions. An object of the present invention is to provide a polyimide seamless tube having a low water absorption and a method of manufacturing the same.

[0008]

Means for Solving the Problems The present inventors have found that a polyimide seamless tube obtained by molding a polyimide precursor solution having a specific chemical structure has substantially the same degree of orientation in the longitudinal direction and the circumferential direction, and has high elasticity. It has been found that the water absorption rate is low, the water absorption rate is low, and the thickness can be made thicker than that conventionally used, and the durability is dramatically improved.

That is, the gist of the present invention is, firstly, a polyimide seamless tube comprising a polyimide represented by the general formula (1) and having a tensile modulus in the longitudinal direction of 480 kg / mm ² or more. . (In the formula,
n shows the integer of 1-20. ]

[0010]

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Second, the polyimide seamless tube is characterized in that the water absorption after water immersion for 24 hours is less than 2% by mass and the dimensional change in the longitudinal and circumferential directions is less than 0.1%. Thirdly, the polyimide seamless tube is characterized in that the degree of molecular chain orientation in the longitudinal direction and the circumferential direction is less than 0.1, and fourthly, 0.1% by mass of carbon black. Fifth, the polyimide seamless tube is characterized by containing less than 5% by mass, and fifth, 0.1 to 10% by mass of a carbon fiber having a length of less than 4 mm. 6th seamless tube
Next, a polyimide precursor solution in which a salt comprising a carboxylic acid represented by the following general formula (2) and a diamine represented by the following general formula (3) is dissolved in a solvent as a solute is formed, and the polyimide precursor is imidized. A method for producing a polyimide seamless tube. [Where l is 0
Represents an integer of 0 to 20; m represents an integer of 0 to 20;
m is 1-20. ]

[0012]

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[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. First, terms used in the present invention will be described. (1) Polyimide An organic polymer in which 80 mol% or more of the repeating unit of the polymer chain has an imide structure. And this organic polymer shows heat resistance. (2) Polyimide precursor An organic compound that becomes a polyimide by ring closure by heating or chemical action. Here, ring closure means that an imide ring structure is formed. (3) Polyimide precursor solution The polyimide precursor is dissolved in a solvent. Here, the solvent refers to a compound which is liquid at 25 ° C. (4) Viscosity The rotational viscosity at 20 ° C. was measured using a DVL-BII type digital viscometer (B type viscometer) manufactured by Tokimec Co., Ltd.

(5) Thickness The thickness of the polyimide film was measured at 10 locations using a Digimatic Micrometer manufactured by Mitutoyo Corporation, and the average value was obtained. (6) Tensile modulus Measured in accordance with JIS K-7127. (7) Dimensional change rate The amount of dimensional change before and after immersion in water was determined as a ratio to the original size. (8) Water absorption The water absorption is shown by the water absorption after immersion in pure water kept at 25 ° C. for 24 hours. (9) Degree of orientation In the crystalline diffraction peak observed by the X-ray transmission method, θ− obtained by fixing the 2θ angle and changing the θ angle is obtained.
The half-width H obtained from the diffraction intensity curve indicates Π calculated by the following equation. Π = (180−H) / 180

Further, the present invention will be described. The polyimide seamless tube of the present invention has a chemical structure represented by the general formula (1), and preferably has a thickness of 55 μm or more. The term "seamless" means not only that the seam is not visually confirmed, but also that points having different characteristic values do not occur in a line in the longitudinal direction in the bending test. In the present invention, the value of the tensile modulus in the longitudinal direction varies depending on the use environment of the seamless tube, the use condition such as pretension, etc., but in consideration of the case where the seamless tube is also used as an intermediate transfer belt or a transfer belt, it is 480 kg / mm. ² or more. 500kg / m
m ² or more is preferable, and 550 kg / mm ² or more is particularly preferable because practical color shift hardly occurs.

The polyimide seamless tube of the present invention contains 0.1% by mass of carbon black from the viewpoint of conductivity.
It is preferred that the content be at least 5 mass%. If it is less than 0.1% by mass, the effect of conductivity is not exhibited, and in order to stably exhibit conductivity and maintain mechanical properties such as breaking strength, the content is preferably 2% by mass or more and less than 5% by mass. In the polyimide seamless tube of the present invention, as a method for further increasing the tensile modulus, the cross-sectional diameter is 1 μm or more and the length is 4 m.
It has been found that the addition of a carbon fiber of less than m improves the elastic modulus. The compounding amount of carbon fiber is 0.1
-10% by mass is preferred. When a carbon fiber having a cross-sectional diameter of less than 1 μm is used, it is difficult to disperse the carbon fiber parallel to the plane direction. When the length is 4 mm or more, dispersion in the raw material solution becomes difficult, and a uniformly dispersed polyimide seamless tube may not be obtained. The amount of carbon fiber is 0.1
When the amount is less than 10% by mass, the compounding effect is not exhibited, and when the amount exceeds 10% by mass, molding becomes difficult. The amount is more preferably 1 to 5% by mass. In addition, a conductive effect is exhibited by blending carbon fibers.

The polyimide seamless tube of the present invention preferably has a water absorption of less than 2% by mass after being immersed for 24 hours in order to prevent the function of the intermediate transfer belt and the transfer belt from being impaired by external influences. % Is more preferable. Similarly, the dimensional change rate in the longitudinal direction and the circumferential direction is preferably less than 0.1, and 0.0
More preferably, it is less than 5.

The polyimide seamless tube of the present invention comprises a polyimide precursor solution in which a salt comprising a carboxylic acid represented by the following general formula (2) and a diamine represented by the following general formula (3) is dissolved as a solute in a solvent. It is obtained by molding and imidizing a polyimide precursor. As a molding method, a known method is adopted, for example, by applying a method such as rotational molding to an inner surface of a resin ring body far and the like, and simultaneously or subsequently, by heating, solvent removal and imidization. Can be produced. In the general formula (2), R ₃ represents hydrogen or a monovalent organic group having 7 or less carbon atoms, and examples of the monovalent organic group include a methyl group, an ethyl group, a propyl group, and an isopropyl group. . Also, l represents an integer of 0 to 20, m represents an integer of 0 to 20, and l + m is an integer of 1 to 20.

In the present invention, any solvent may be used as long as it dissolves a salt comprising a carboxylic acid represented by the general formula (2) and a diamine represented by the general formula (3). For example, an aprotic polar solvent,
N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphoramide, ether compounds, 2-methoxyethanol, 2-ethoxyethanol, 2- (methoxymethoxy) Ethoxyethanol, 2-isopropoxyethanol, 2-butoxyethanol, tetrahydrofurfuryl alcohol, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monoethyl ether,
Tetraethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, polyethylene glycol, polypropylene glycol, tetrahydrofuran , Dioxane, 1,2-dimethoxyethane,
Diethylene glycol dimethyl ether, diethylene glycol diethyl ether, water-soluble alcohol-based compounds, methanol, ethanol, 1-propanol,
2-propanol, tert-butyl alcohol, ethylene glycol, 1,2-propanediol, 1,3-
Propanediol, 1,3-butanediol, 1,4-
Butanediol, 2,3-butanediol, 1,5-pentanediol, 2-butene-1,4-diol, 2-
Methyl-2,4-pentanediol, 1,2,6-hexanetriol, diacetone alcohol, etc., benzyl alcohol for water-insoluble alcohol compounds, and 1,5,5-trimethyl-3-cyclohexanone for ketone compounds However, in others, γ-butyrolactone is mentioned,
Each of the above compounds can be used alone or in combination of two or more. Among them, particularly preferred examples include N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, diethylene glycol monomethyl ether as a single solvent, and N-methylpyrrolidone and diethylene glycol monomethyl ether, N-methylpyrrolidone as a mixed solvent. Methylpyrrolidone and methanol,
Examples include a combination of N-methylpyrrolidone and 2-methoxyethanol.

The viscosity of the polyimide precursor solution in the present invention is preferably 50 poise or more, more preferably 200 poise.
More than poise. The degree of orientation of molecular chains in the longitudinal direction and the circumferential direction of the polyimide seamless tube of the present invention is less than 0.1, and does not substantially show anisotropy in the longitudinal direction and the circumferential direction. This is a salt of a carboxylic acid represented by the general formula (2) and a diamine represented by the general formula (3). A polyimide precursor generally has a low molecular weight, and a molecular chain against an external force applied when molded in a polyimide precursor state. It is difficult for the molecules to be polymerized due to friction between the tube coating and the mold surface, which tend to shrink due to the intramolecular ring closure reaction, because the polymerization reaction occurs at the same time during the imidization step. Inhibited by movement. Therefore, the polyimide molecules are not oriented in a specific direction in the longitudinal direction and the circumferential direction. Therefore, the polyimide seamless tube of the present invention has substantially the same elastic modulus in the longitudinal direction and the circumferential direction.

[0021]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1 10.27 g of paraphenylenediamine (0.095 mol
l) was dissolved in 355 g of N, N-dimethylacetamide and stirred at room temperature. To this, 4.36 g (0.02 mol) of pyromellitic dianhydride and 23.54 g (0.08 mol) of biphenyltetracarboxylic dianhydride were added over 1 minute, and the mixture was stirred at room temperature for 2 hours. Methanol 0.
48 g (0.015 mol) and 0.024 g of dimethylaminoethanol were added, and the mixture was stirred on a 70 ° C. water bath for 2 hours. After cooling to room temperature, 1.001 g (0.005 mol) of diaminodiphenyl ether was added, and
When stirring was continued for a time, a uniform yellow-orange transparent solution was obtained (solute concentration: 10% by mass). The thus obtained polyimide precursor solution was spray-coated on a cylindrical mold. The temperature was raised to 300 ° C. over 5 hours while gradually raising the temperature in a nitrogen atmosphere to imidize the polyimide precursor, and the polyimide seamless tube was released from the mold. When this polyimide seamless tube was cut open and the thickness was measured, it was 57 μm. When the tensile elastic modulus in the longitudinal direction of the cut tube was measured, the value was 500 kg / mm ² or more. The water absorption of the cut tube was measured.
% By mass, and the dimensional change rate in the longitudinal direction and the circumferential direction was less than 0.1%. When this tube was measured by X-ray transmission diffraction method, crystalline diffraction was observed around 2θ = 11 °. Therefore, the diffraction intensity distribution when the 2θ was fixed and the θ angle was changed was measured. No change was observed, and the degree of orientation was 0.

Example 2 10.27 g of paraphenylenediamine (0.095 mol)
l) was dissolved in 341 g of N, N-dimethylacetamide and stirred at room temperature. To this, 8.72 g (0.04 mol) of pyromellitic dianhydride and 17.65 g (0.06 mol) of biphenyltetracarboxylic dianhydride were added over 1 minute, and the mixture was stirred at room temperature for 2 hours. Methanol 0.
48 g (0.015 mol) and 0.024 g of dimethylaminoethanol were added, and the mixture was stirred on a 70 ° C. water bath for 2 hours. After cooling to room temperature, 1.001 g (0.005 mol) of diaminodiphenyl ether was added, and
When stirring was continued for a time, a uniform yellow-orange transparent solution was obtained (solute concentration: 10% by mass). The thus obtained polyimide precursor solution was spray-coated on a cylindrical mold. This was heated to 300 ° C. over 5 hours while gradually raising the temperature under a nitrogen atmosphere to imidize the polyimide precursor, and the polyimide seamless tube was released from the mold. When this polyimide seamless tube was cut open and the thickness was measured, it was 56 μm. When the elastic modulus of the cut tube was measured in the longitudinal direction, it showed a value of 500 kg / mm ² or more.
The water absorption of the cut tube was measured and found to be 1.2% by mass, and the dimensional change in the longitudinal and circumferential directions was less than 0.1%. When this tube was measured by X-ray transmission diffraction method, crystalline diffraction was observed around 2θ = 11 °. Therefore, the diffraction intensity distribution when the 2θ was fixed and the θ angle was changed was measured. No change was observed, and the degree of orientation was 0.

Example 3 10.27 g of paraphenylenediamine (0.095 mol
l) was dissolved in 328 g of N, N-dimethylacetamide and stirred at room temperature. To this, 13.1 g (0.06 mol) of pyromellitic dianhydride and 11.8 g (0.04 mol) of biphenyltetracarboxylic dianhydride were added in 1 part.
And stirred at room temperature for 2 hours. Methanol 0.4
8 g (0.015 mol) and 0.024 g of dimethylaminoethanol were added, and the mixture was stirred on a 70 ° C. water bath for 2 hours. After cooling to room temperature, 1.001 g (0.005 mol) of diaminodiphenyl ether was added, and stirring was further continued for 1 hour to obtain a uniform yellow-orange transparent solution (solute concentration: 10% by mass). The obtained polyimide precursor solution was spray-coated on a cylindrical mold. This was heated to 300 ° C. over 5 hours while gradually raising the temperature under a nitrogen atmosphere to imidize the polyimide precursor, and the polyimide seamless tube was released from the mold. When this polyimide seamless tube was cut open and the thickness was measured, it was 57 μm. When the elastic modulus of the cut tube was measured in the longitudinal direction, the tube showed a value of 520 kg / mm ² or more. The water absorption of the cut tube was measured to be 1.1% by mass, and the dimensional change in the longitudinal and circumferential directions was less than 0.1%. When this tube was measured by X-ray transmission diffraction method, crystalline diffraction was observed around 2θ = 11 °. Therefore, the diffraction intensity distribution when the 2θ was fixed and the θ angle was changed was measured. No change was observed, and the degree of orientation was 0.

Example 4 2% by mass of carbon black was added to the solid content of the polyimide precursor solution obtained in Example 1 and dispersed using a kneader. The polyimide precursor solution obtained by dispersing the carbon black thus obtained is spray-coated on a mold,
Up to 300 ° C while gradually raising the temperature under a nitrogen atmosphere, 5
The temperature was raised over time to imidize the polyimide precursor, and the polyimide seamless tube was released from the mold. When this polyimide seamless tube was cut open and the thickness was measured, it was 67 μm. The elastic modulus in the longitudinal direction was measured for the cut-out tube.
It showed a value of 50 kg / mm ² or more. The water absorption of the cut tube was measured to be 1.1% by mass, and the dimensional change in the longitudinal and circumferential directions was 0.1%.
Was less than. When this tube was measured by X-ray transmission diffraction method, crystalline diffraction was observed around 2θ = 11 °. Therefore, the diffraction intensity distribution when the 2θ was fixed and the θ angle was changed was measured. No change was observed, and the degree of orientation was 0.

Example 5 To the polyimide precursor solution obtained in Example 1 was added 4% by mass of carbon fiber based on the solid content, and the mixture was dispersed using a kneader.
The cylindrical mold was immersed in the polyimide precursor solution in which the carbon fibers thus obtained were dispersed, and was gently pulled up. A ring-shaped die having an inner diameter 0.6 mm larger than the outer diameter of the mold was allowed to fall freely through the cylindrical mold and passed therethrough.
Further, the temperature is raised stepwise under a nitrogen atmosphere to 300 ° C.
The polyimide precursor was imidized by raising the temperature for 5 hours until the polyimide seamless tube was released from the mold. When this polyimide seamless tube was cut open and the thickness was measured, it was 56 μm. When the elastic modulus of the cut tube was measured in the longitudinal direction, it showed a value of 530 kg / mm ² or more. The water absorption of the cut tube was measured to be 1.3% by mass, and the dimensional change in the longitudinal and circumferential directions was less than 0.1%. When this tube was measured by X-ray transmission diffraction method, crystalline diffraction was observed around 2θ = 11 °. Therefore, the diffraction intensity distribution when the 2θ was fixed and the θ angle was changed was measured. No change was observed, and the degree of orientation was 0.

Comparative Example 1 10.27 g of paraphenylenediamine (0.095 mol
l) is dissolved in 386 g of N, N-dimethylacetamide
And stirred at room temperature. This is pyromellitic dianhydride
17.4 g (0.08 mol) and biphenyltetra
5.88 g (0.02 mol) of carboxylic dianhydride was added.
Then, the mixture was stirred at room temperature for 2 hours to obtain a uniform yellow-orange transparent solution.
(Solute concentration 8% by mass). The obtained polyimide precursor solution
Was spray coated. Do not dry at 80 ° C as appropriate.
Spray coat until the specified coating thickness is reached.
The temperature is raised stepwise under a nitrogen atmosphere by 300
Imidation was carried out by raising the temperature to 5 ° C over 5 hours.
Was. Remove the imidized tube from the mold,
Obtain an imide seamless tube, cut it out and measure its thickness.
As a result, it was 50 μm. The opened Ju
When the elastic modulus was measured for the probe, 430 kg /
mm ^TwoAnd a low value.

Comparative Example 2 10.8 g (0.1 mol) of paraphenylenediamine
Is dissolved in 359 g of N, N-dimethylacetamide,
The mixture was stirred at room temperature. This is followed by pyromellitic dianhydride.
3 g (0.02 mol) and 23.5 g (0.08 mol) of biphenyltetracarboxylic dianhydride were added over 1 minute, and the mixture was stirred at room temperature for 2 hours. 0.48 g of methanol
(0.015 mol) and 0.024 g of dimethylaminoethanol were added, and the mixture was stirred in a 70 ° C hot water bath for 2 hours.
After cooling to room temperature, diaminodiphenyl ether
001 g (0.005 mol) was added, and stirring was further continued for 1 hour to obtain a uniform yellow-orange transparent solution (solute concentration: 10% by mass). The thus obtained polyimide precursor solution was spray-coated on the outer surface of a cylindrical mold in the same manner as in Comparative Example 1. This was heated up to 300 ° C. over 5 hours while gradually raising the temperature under a nitrogen atmosphere to perform imidization. However, the coating was broken, and a tube could not be obtained. The thickness of the coated piece was 55 μm.

Comparative Example 3 10.8 g (0.1 mol) of paraphenylenediamine
Is dissolved in 211 g of N, N-dimethylacetamide,
The mixture was stirred at room temperature. To this was added 29.4 g (0.1 mol) of biphenyltetracarboxylic dianhydride, and the mixture was added at room temperature for 2 hours.
After stirring for a time, a uniform yellow-orange transparent solution was obtained (solute concentration: 16% by mass). The polyimide precursor solution thus obtained was applied to the outer surface of the cylindrical mold with a brush. Further, the precursor solution was uniformly applied to the outer surface of the mold by passing through a ring-shaped die having an inner diameter larger by 300 μm. This is heated up to 300 ° C in a nitrogen atmosphere while increasing the temperature stepwise.
It was imidized by raising the temperature over 5 hours, and the polyimide seamless tube was released from the mold. When this polyimide seamless tube was cut open and the thickness was measured, it was 40 μm. For the cut tube,
When the elastic modulus was measured, it was found to be 440 to 470 in the circumferential direction.
kg / mm ² , but 420 kg in the longitudinal direction.
/ Mm ² only. The water absorption of the cut tube was measured and found to be 0.9% by mass.
When this tube was measured by the X-ray transmission diffraction method, 2θ =
Since diffraction of the crystallinity was observed at around 11 °, the diffraction intensity distribution when the θ was changed while fixing 2θ was measured. As a result, a change in the intensity was observed, and the degree of orientation was about 0. 0 in the circumferential direction.
It was 4. Table 1 shows the results of the characteristic values of the polyimide seamless tube.

[0030]

[Table 1]

[0031]

As described above, the polyimide seamless tube of the present invention has a low degree of molecular chain orientation in the longitudinal and circumferential directions, does not substantially exhibit anisotropy, and has a high elasticity in the longitudinal and circumferential directions. It has a low water absorption rate. Among them, those containing carbon black have conductivity and can solve the problem of chargeability, and those containing carbon fibers have conductivity and can solve the problem of chargeability. As well as having better mechanical properties. Therefore, the polyimide seamless tube of the present invention can run stably for a long time as a heat fixing tube of a copying machine or a printer. Further, according to the present invention, such a polyimide seamless tube can be easily manufactured.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C08L 79/08 C08L 79/08 Z // B29K 79:00 B29K 79:00 B29L 23:00 B29L 23:00 F term (for reference) 4F072 AA02 AA07 AB10 AB14 AD45 AE08 AF01 AK03 AL11 AL16 4F205 AA40A AG08 GA05 GA08 GB01 GC01 GE02 GF25 GN13 GN28 GN29 GW05 4J002 CM041 DA017 DA036 FA047 FD017 FD116 GM00 GQB0404G04B04B04J04 TA22 TB01 TB03 UA121 UA122 UA131 UA132 UB121 XA15 XA16 XA19 XB36 YA06 YA13 ZA11 ZA32 ZA44 ZA60 ZB41 ZB47 ZB51

Claims (6)

[Claims] 1. A polyimide made of the general formula (1) having a tensile modulus in the longitudinal direction of 480 kg / mm ^2.
A polyimide seamless tube characterized by the above. [In formula, n shows the integer of 1-20. [Formula 1] 2. The polyimide seamless according to claim 1, wherein the water absorption after immersion in water for 24 hours is less than 2% by mass, and the dimensional change in the longitudinal and circumferential directions is less than 0.1%. tube. 3. The polyimide seamless tube according to claim 1, wherein the degree of molecular chain orientation in the longitudinal direction and the circumferential direction is less than 0.1. 4. A carbon black containing at least 0.1% by mass
The seamless polyimide tube according to claim 1, wherein the polyimide seamless tube contains less than 10% by mass. 5. A carbon fiber having a length of less than 4 mm is 0.1 to
The polyimide seamless tube according to claim 1, which contains 10% by mass. 6. A polyimide precursor solution in which a salt comprising a carboxylic acid represented by the following general formula (2) and a diamine represented by the following general formula (3) is dissolved in a solvent as a solute, 2. The method for producing a polyimide seamless tube according to claim 1, wherein [Wherein, l represents an integer of 0 to 20, and m represents 0 to 20.
And l + m is 1 to 20. [Chemical formula 2]