JPH068350A - Composite tubular article and production thereof - Google Patents

Abstract

PURPOSE:To increase the bonding strength of a tubular outer layer made of fluoroplastic and a tubular inner layer made of a polyimide layer because the release of both layers is generated because of insufficiency in bonding strength in such a case that the composite tubular article consisting of both layers is used as the belt used in an image forming apparatus due to a belt fixing method to bring about the lowering of image quality. CONSTITUTION:A tubular outer layer made of fluoroplastic and a tubular inner layer made of a polyimide resin are strongly and integrally bonded by interposing an intermediate layer containing a tetrafluoroethylene/perfluoroalkylvinyl ether copolymer, a polyimide resin, an inorg. fiber and a surfactant as essential components.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a copying machine, a facsimile,
The present invention relates to a composite tubular article that can be used as a transfer or fixing belt of an image forming apparatus such as a printer, a conveyor belt of a silicon wafer, and the like, and a manufacturing method thereof.

[0002]

2. Description of the Related Art A heat roller fixing method is known as an image fixing method for a transfer sheet in an image forming apparatus. In this heat roller fixing method, for example, as shown in FIG. 2, the heat roller 1 and the press roller 2 are vertically opposed to each other, and the transfer paper 3 is fed between the rollers 1 and 2. Heat generated by the heater 4 built in the transfer paper 3
The toner 5 temporarily adhered to the toner is melted and fixed, and is pressed by the press roller 2 to strengthen the fixing, thereby forming an image by the toner on the transfer paper.

By the way, in the case of such a heat roller fixing method, in order to fix the toner on the transfer paper, it is necessary to set the heat roller to a temperature higher than the melting temperature of the toner, but this high temperature heating makes the toner sticky. The transfer paper was developed, and the transfer paper could not be peeled off from the heat roller, resulting in deterioration of image quality and paper jam.

In order to solve this problem, as shown in FIG. 1, in addition to the heat roller 1 and the press roller 2, a peeling roller 7 is disposed as a third roll on the side of the heat roller 1 to peel from the heat roller 1. A belt fixing method has been proposed in which a fixing belt 8 is stretched between the roller 7 and the roller 7.

In the image fixing by the belt fixing method, the transfer belt 3 on which the toner 5 is temporarily attached is sent between the heat roller 1 and the press roller 2 while the fixing belt 8 is driven and the heater 4 is heated. Done in. The toner 5 heated and pressed between the heat roller 1 and the press roller 2 is fixed on the transfer paper 3, but the heating causes the adhesiveness to develop, and the transfer paper 3 is temporarily attached to the fixing belt 8. It is conveyed to the position of the peeling roller 7. Because of the cooling action during this conveyance and the peeling property of the peeling roller 7, the peeling is surely performed, so that a clear image 6 can be obtained.

As a belt used in such a belt fixing method, there is known a composite tubular article including a fluororesin tubular outer layer and a polyimide resin tubular inner layer formed on an inner peripheral surface of the outer layer. Then, as a method for producing this composite tubular product, a fluororesin solution is applied to the inner peripheral surface of the cylinder to form a fluororesin tubular product by heating, and then,
By supplying a polyamic acid solution into the tubular article and running a bullet-shaped or spherical traveling body, the polyamic acid solution is applied to the inner peripheral surface of the fluororesin tubular article, and then the polyamic acid is converted into an imide. A method is known in which a polyimide tubular material is formed and then taken out from a cylinder (Japanese Patent Application Laid-Open No. HEI 2).
No. 43046).

[0007]

However, in the above composite tubular article, the adhesive strength between the fluororesin tubular outer layer and the polyimide resin tubular inner layer is not sufficient, so that the two layers are stuck between both layers during use as a fixing or transfer belt. There is a problem that peeling is likely to occur and image quality is deteriorated.

[0008]

Means for Solving the Problems As a result of intensive research to solve the above problems of the prior art, the present inventor has established a fluororesin tubular outer layer and a polyimide resin tubular inner layer by an intermediate layer containing specific components. It was found that the bonding strength of both layers can be improved by bonding, and a composite tubular product that is less likely to cause peeling can be obtained, and the present invention has been completed.

That is, in the composite tubular article according to the present invention, the fluororesin tubular outer layer and the polyimide resin tubular inner layer are composed of a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (hereinafter referred to as PFA), a polyimide resin, and an inorganic filler. It is characterized by being integrally bonded through an intermediate layer containing a material and a surfactant.

What is important in the composite tubular article according to the present invention is PFA and polytetrafluoroethylene (hereinafter referred to as PFA).
TFE), a toterafluoroethylene-hexafluoropropylene copolymer, an ethylene-tetrafluoroethylene copolymer, or a tubular outer layer made of a fluororesin such as a mixture thereof and a tubular inner layer made of a polyimide resin.
It is to join and integrate by a tubular intermediate layer containing FA, a polyimide resin, an inorganic filler and a surfactant.
By using the intermediate layer containing these essential components, the outer layer and the inner layer can be firmly joined and integrated.

The thickness of the outer layer and the inner layer of the composite tubular article is not particularly limited, but when it is used as a fixing or transfer belt, the tubular outer layer made of a fluororesin is about 5 to 50 μm, and the outer layer made of a polyimide resin. It has been found suitable for the tubular inner layer to have a thickness of about 10 to 150 μm. Further, the thickness of the intermediate layer for joining and integrating these outer layer and inner layer is not particularly limited, but usually,
It is about 0.5 to 10 μm.

Since the fixing or transfer belt is preferably electrically conductive, in the composite tubular article according to the present invention, at least one of the fluororesin tubular outer layer, the intermediate layer or the polyimide resin tubular inner layer contains carbon powder, It can be made conductive by including a conductive substance such as graphite powder or metal powder.

The bonding strength between the outer layer and the inner layer in the composite tubular article can be known by, for example, performing a pencil hardness test on the outer layer, and the composite tubular article according to the present invention has a pencil hardness test at a temperature of 25 ° C. 2H or more, the conventional product shows a value of less than H.

In the present invention, in order to further strengthen the bonding strength between the outer layer and the inner layer, the tubular outer layer made of a fluororesin is made of PFA or a mixture of PFA and another fluororesin. The weight ratio of PFA in it is 1
It is preferably formed from a mixture which is 0% or more.

Next, an example of a method for manufacturing the composite tubular article will be described. In this manufacturing method, a fluororesin dispersion is applied to the inner peripheral surface of the cylinder and then heated to form a fluororesin tubular product on the inner peripheral surface of the cylinder, and then PFA or polyimide is formed on the inner peripheral surface of the fluororesin tubular product. A precursor (polyamic acid), an inorganic filler and a surfactant are dissolved or dispersed in a solvent and applied and dried to make PFA, a polyimide precursor, an inorganic filler and a surfactant an essential component. An intermediate layer is formed, then a polyimide precursor solution is applied onto this intermediate layer, and then heated to imidize the polyimide precursor as an intermediate layer forming component and the polyimide precursor in the solution applied onto the intermediate layer. By converting, to form a composite tubular article that is integrally joined to the polyimide resin tubular article through the intermediate layer on the inner peripheral surface of the fluororesin tubular article, It is characterized in that retrieving the composite tubular article from the cylinder.

[0016] In this method, first, a fluororesin dispersion is applied to the inner peripheral surface of a cylinder made of a heat-resistant material such as metal, glass, or ceramic, and then heated to form a fluororesin tubular product on the inner peripheral surface of the cylinder. Is formed. The state of the inner peripheral surface of the cylinder is related to the surface roughness of the outer peripheral surface of the obtained composite tubular product, and in order to make the outer surface of the composite tubular product smooth, the surface roughness of the inner peripheral surface of the cylinder is about 10 μm or less. It is preferable to adjust to. Further, if a mold-releasing resin such as a silicone resin is applied to the inner peripheral surface of the cylinder, the composite tubular product can be easily released.

The dispersion used here is PTF.
Fluorine resin such as E, FEP, PFA is included,
Considering the coating workability on the cylinder, the fluororesin concentration is about 5 to 60% by weight, and the viscosity (B at the temperature during the coating work).
It is preferable that the viscosity (measured by a viscometer) be about 1 to 100 poise.

If desired, a suitable amount of additives such as surfactants and thickeners can be added to the fluororesin dispersion. Further, by adding a conductive powder to this dispersion, conductivity can be imparted to the fluororesin tubular product. In order to firmly bond the fluororesin tubular outer material to the inner layer via the intermediate layer, it is a PFA dispersion as a fluororesin dispersion or a mixed dispersion of PFA and another fluororesin in the mixture. Weight ratio of PFA to 10%
It is particularly preferable to use the above.

The application of the fluororesin dispersion to the inner peripheral surface of the cylinder is carried out by dipping the cylinder in the fluororesin dispersion and pulling up, after supplying the fluororesin dispersion to one end opening of the cylinder,
Appropriate means such as a method of running a running body (bullet shape, spherical shape, etc.) in the cylinder, a method of spray-coating the inner surface of the cylinder with a fluororesin dispersion, a method of applying a brush, and the like can be adopted.

The running body used in the above method may be a hard one made of metal, hard plastic, glass or the like. The running is carried out by the cylinder with the cylinder standing vertically, compressed air or Depending on the method of using the gas explosive force, the method of pulling the running body using a tow wire, etc.

In order to prevent the generation of voids, the heating after coating is carried out by first removing the solvent (usually water) of the dispersion and then raising the temperature above the melting point of the fluororesin. Is preferred. The thickness of the fluororesin tubular product can be adjusted by repeating coating and heating.

After the tubular body made of fluororesin is formed on the inner peripheral surface of the cylinder in this way, an intermediate layer is formed on the inner peripheral surface of the tubular body. The intermediate layer functions as a primer for firmly joining and integrating the fluororesin tubular product and the polyimide resin tubular product formed on the inner peripheral surface of the fluororesin tubular product.

The intermediate layer is formed by applying a solution obtained by dissolving or dispersing PFA, a polyimide precursor, an inorganic filler and a surfactant in a solvent to the inner peripheral surface of the fluororesin tubular article,
This can be formed by drying and removing the solvent. In applying this liquid, the same method as in forming the fluororesin tubular product on the inner peripheral surface of the cylinder can be adopted. Further, in the drying after coating, the temperature is set so as not to cause imide conversion of the polyimide precursor. The imide conversion temperature of the polyimide precursor may vary depending on the components used for synthesizing the precursor, but it is usually about 200 to 400 ° C., and therefore the drying temperature is also usually lower than this temperature. By repeating this application and drying, the thickness of the intermediate layer can be adjusted.

The intermediate layer-forming liquid has a PFA of 1.25 to 2.5% by weight, a polyimide precursor of 1.75 to 3.5% by weight, an inorganic filler of 0.3 to
A composition of 0.6% by weight, 1.7 to 3.4% by weight of surfactant and 90 to 95% by weight of solvent has been found to be suitable.

As the polyimide precursor for forming the intermediate layer, the same polyimide precursor as that used for forming the polyimide resin tubular article described later can be used. Further, as the inorganic filler, those having a particle size of about 50 μm or less can be used, and specific examples thereof include silica, alumina, titanium oxide, iron oxide,
Zinc oxide, magnesium oxide, tin oxide, antimony oxide, barium ferrite, strontium ferrite,
Talc, clay, mica, calcium silicate, glass,
Glass hollow spheres, glass fibers, calcium titanate, lead zirconate titanate, aluminum nitride, silicon carbide, cadmium sulfide, iron, copper, nickel, gold, silver, aluminum, carbon black, graphite, carbon fibers and the like. it can. Further, specific examples of the surfactant include alkyl polyoxyethylene ether, alkylcarbonyloxyethylene, p-alkylphenyl polyoxyethylene ether, fatty acid polyhydric alcohol ester, fatty acid polyhydric alcohol polyoxyethylene, fatty acid sucrose ester and the like. A nonionic surfactant can be mentioned.

In the method according to the present invention, after the fluororesin tubular product and the intermediate layer are successively formed on the inner peripheral surface of the cylinder in this manner, the polyimide resin tubular product is formed on the intermediate layer.

The polyimide precursor solution used to form the polyimide resin tubular article can be obtained by reacting tetracarboxylic dianhydride or its derivative with approximately equimolar amounts of diamine in an organic polar solvent. This tetracarboxylic dianhydride is represented by the following chemical formula 1.

[0028]

[Chemical 1]

Specific examples of the tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3 ',
4,4'-benzophenone tetracarboxylic dianhydride,
3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,3,3', 4'-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride 1,2,5,6-naphthalenetetracarboxylic dianhydride, 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 (3,3
4-dicarboxyphenyl) ether dianhydride, ethylene tetracarboxylic acid dianhydride and the like can be mentioned.

Specific examples of the diamine to be reacted with such a tetracarboxylic dianhydride include 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4-diaminodiphenylmethane,
3,3'-diaminodiphenylmethane, 3,3'-dichlorobenzidine, 4,4'-aminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 1,5-
Diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3'-dimethyl-4,4'-diaminobiphenyl, benzidine, 3,3'-dimethylbenzidine, 3,3'-dimethoxybenzidine, 4,4 '
-Diaminophenyl sulfone, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenylpropane, 2,4-bis (β-amino-t-butyl) toluene, bis (p-β-amino-t-butyl) Phenyl) ether, bis (p-β-methyl-δ-aminophenyl) benzene, bis-p- (1,1-dimethyl-5-aminopentyl) benzene, 1-isopropyl-2,4-m-phenylenediamine, m-xylylenediamine, p-xylylenediamine, di (p-aminocyclohexyl) methane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine,
Decamethylenediamine, diaminopropyltetramethylenediamine, 3-methylheptamethylenediamine, 4,
4-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2-bis- (3-aminopropoxy) ethane, 2,2-dimethylpropylenediamine, 3
-Methoxyhexamethylenediamine, 2,5-dimethylhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 3-methylheptamethylenediamine, 5
-Methylnonamethylenediamine, 2,17-diaminoeicosadiamine, 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)} O (CH 2) O (CH 2) N
_{H 2, H 2 N (CH} 2) 3 S (CH 2) 3 NH 2, H 2
_{N (CH 2) 3 N (} CH 3) (CH 2) NH 3 , and the like.

Further, as a preferable example of the organic polar solvent used when the tetracarboxylic dianhydride and the diamine are reacted, N, N-dialkylamides such as N, N-dimethylformamide and N, N-dimethylacetamide are used. Can be mentioned. These can be easily removed from the polyimide precursor solution by evaporation, substitution, diffusion or the like. Further, polar solvents other than the above, for example, N, N-diethylformamide, N, N-dimethylacetamide, N, N-dimethylmethoxyacetamide, dimethylsulfoxide, hexamethylphosphortriamide, N-methyl-2-pyrrolidone, pyridine , Dimethyl sulfone, tetramethylene sulfone, dimethyl tetramethylene sulfone, etc. may be used, and these organic polar solvents may be used alone or in combination of two or more kinds.

In addition, it is also possible to mix one or more of phenols such as cresol, phenol and xylenol, benzonitrile, hexane, benzene and toluene with these polar solvents. However, the use of water should be avoided in order to prevent the resulting polyimide precursor from lowering the molecular weight due to hydrolysis.

A polyimide precursor solution is obtained by reacting the above tetracarboxylic dianhydride and diamine in an organic polar solvent for about 0.5 to 10 hours. The monomer concentration during the reaction can be set according to various factors, but is usually about 5 to 30% by weight. The reaction temperature is 80 ° C.
It is preferable to set the following (more preferably 5 to 60).
C).

When the tetracarboxylic dianhydride and the diamine are reacted in the organic polar solvent in this manner, the solution viscosity increases as the reaction proceeds, but a polyimide precursor having a logarithmic viscosity [η] of 0.5 or more is used. Preferably. A polyimide resin layer formed by using a polyimide precursor having a logarithmic viscosity [η] of 0.5 or more is particularly excellent in heat resistance and has an advantage. The logarithmic viscosity is a value calculated by the following mathematical formula 1 by measuring the dropping time of the polyimide precursor solution and the solvent by using a capillary viscometer.

[0035]

[Equation 1]

The polyimide resin tubular product can be formed by applying a polyimide precursor solution to the inner peripheral surface of the intermediate layer and heating it. During this heating, the polyimide precursor solution applied on the intermediate layer is imide-converted to form a polyimide resin tubular product, and the polyimide precursor as an intermediate layer-forming component is also imide-converted.
And during this conversion, the intermediate layer functions as a primer,
The fluororesin tubular product and the polyimide resin tubular product are firmly joined and integrated via the intermediate layer.

To apply the above-mentioned polyimide precursor solution to the inner peripheral surface of the intermediate layer, the same coating method as the coating of the fluororesin dispersion on the inner peripheral surface of the cylinder can be adopted. From the viewpoint of coating workability, the viscosity of the polyimide precursor solution (measured with a B-type viscometer at the temperature during coating work) is about 10 to 100.
It is preferably 0 poise.

The heating temperature at the time of forming the tubular body made of a polyimide resin can be appropriately set. First, the ring-closing water and the solvent generated during the imide conversion are removed by evaporation by heating at a low temperature of about 80 to 180 ° C., and then about 250 to 400. It is preferable to employ a multi-step heating method in which the temperature is raised to 0 ° C. to complete the imide conversion. The heating time is set according to the heating temperature, etc.
It takes about 20 to 60 minutes for both the low temperature heating and the subsequent high temperature heating. If this multi-step heating method is adopted, it is possible to prevent the generation of microvoids in the polyimide tubular material due to the evaporation of the ring-closing water and the solvent that accompany the imide conversion.

At the time of heating for forming the polyimide resin tubular article, the polyimide precursor as an intermediate layer forming component is also imide-converted into a polyimide. Since the polyimide in the intermediate layer and the tubular layer made of polyimide resin formed on the inner peripheral surface of the intermediate layer are of the same system, the bonding strength between them is large.

After forming the composite tubular article on the inner peripheral surface of the heat-resistant cylinder in this manner, the tubular article may be separated from the inner peripheral surface of the cylinder and taken out. The peeling work is, for example,
A small through hole may be provided in the wall of the cylinder in advance, and air may be forced into the hole.

[0041]

EXAMPLES The present invention will be described in more detail below with reference to examples.

Example 1 (Preparation of Polyimide Precursor Solution) 3,3 ', 4,4'-
Biphenyl tetracarboxylic acid dianhydride and 4,4'-diaminodiphenyl ether are used in N-methyl-2-
Dissolved in vinylpyrrolidone (monomer concentration 20% by weight), reacted at a temperature of 20 ° C. for 5 hours to have a viscosity of 35,000 poise (temperature of 50 ° C., measured value by a B-type viscometer), and a logarithmic viscosity [η] of 2.8. A polyimide precursor solution is obtained.

Then, with respect to 100 parts by weight of this solution,
33 parts by weight of N-methyl-2-pyrrolidone is added and diluted to adjust the viscosity at a temperature of 50 ° C. to 1500 poise.

(Preparation of Composite Tubular Product) Inner diameter 55 mm, wall thickness 4 mm, length 600 mm, and surface roughness of inner peripheral surface of stainless steel cylinder of 1 μm or less.
Dispersion of wt% was applied by a spray gun, then 100 ° C for 10 minutes, 250 ° C for 10 minutes,
Heat at 400 ° C. for 5 minutes to form a 15 μm thick PFA tubing.

Next, 2% by weight of PFA, 2% by weight of the polyimide precursor solution, 0.3% by weight of silica powder having a particle size of 5 μm,
15. Surfactant alkyl polyoxyethylene ether (Rohm & Haas, trade name Triton X-100) 2% by weight, ethylene glycol 75% by weight, dimethylacetamide 3% by weight and N-methyl-2-pyrrolidone 15.
An intermediate layer forming solution of 7% by weight is applied to the inner peripheral surface of the PFA tubular product by a spray gun and heated at 150 ° C. and 250 ° C. for 10 minutes in sequence to form an intermediate layer having a thickness of 3 μm.

Then, this cylinder was immersed in the above polyimide precursor solution (adjusted to a liquid temperature of 50 ° C.) and pulled up,
With this held vertically, a bullet-shaped running body having an outer diameter of 54.4 mm is run by its own weight to apply the polyimide precursor solution. Then, by heating at 100 ° C. for 10 minutes to remove the ring-closing water and the solvent by evaporation, and further by heating at 300 ° C. for 30 minutes to form a polyimide resin tubular article having a thickness of 30 μm, and then preliminarily forming on the cylinder wall. Air was pressure-fed from the small through-hole provided, and the composite tubular product was peeled from the inner peripheral surface of the cylinder.

The bonding strength between the PFA-made tubular outer layer and the intermediate layer was measured by a pencil hardness test (temperature: 25 ° C.) and found to be 2H, which is a value that can be practically used.

Example 2 (Preparation of Polyimide Precursor Solution) The procedure of Example 1 was repeated except that 4,4′-diaminodiphenyl ether was replaced with paraphenylenediamine, and the viscosity was 20000 poise and the logarithmic viscosity [η] 2 A polyimide precursor solution of 0.5 is obtained, and 10 parts by weight of N-methyl-2-pyrrolidone is added to 100 parts by weight of this solution to dilute the solution to adjust the viscosity to 3000 poises.

(Production of Composite Tubular Product) Inner diameter 55 mm, wall thickness 5 mm, length 500 mm, chrome-plated iron cylinder with inner peripheral surface roughness of 1 μm or less, and PFA and P
A fluororesin dispersion (concentration of fluororesin 50% by weight) is prepared by mixing TFE in a weight ratio of 8/1.

Then, the cylinder is dipped in the fluororesin-mixed dispersion and pulled up, the cylinder is erected vertically, and a bullet-shaped body having an outer diameter of 54.9 mm is caused to travel by its own weight to apply the dispersion. , Then 10
Heated at 0 ° C for 10 minutes, 250 ° C for 10 minutes, and 400 ° C for 5 minutes to give a fluororesin tubular article (PFA and P
TFE is 8/1 by weight).

Then, an intermediate layer was formed on the inner peripheral surface of the fluororesin tubular article in the same manner as in Example 1, and then the same procedure as in Example 1 was carried out except that the above polyimide precursor solution was used. A polyimide resin tubular product was formed and then peeled from the cylinder to obtain a composite tubular product.

The bonding strength between the fluororesin tubular outer layer made of a mixture of PFA and PTFE and the intermediate layer was measured by a pencil hardness test and found to be 2H, which was a value that could be practically used.

Example 3 A glass tube having an inner diameter of 123 mm, a wall thickness of 3 mm and a length of 500 mm and a smooth inner peripheral surface was used as a cylinder, which was immersed in a PFA dispersion mixed with carbon powder and pulled up. A bullet-shaped body having an outer diameter of 122.92 mm is run under a pressure condition of 0.2 kg / cm ² to apply the dispersion. Then, it is heated at 100 ° C. for 10 minutes, 250 ° C. for 10 minutes, and 400 ° C. for 5 minutes to form a PFA-made tubular article having a thickness of 10 μm and having conductivity. The ratio of carbon to the total weight of carbon and PFA in the mixed dispersion is 4% by weight.
Is.

Then, an intermediate layer having a thickness of 3 μm is formed on the inner peripheral surface of the PFA tubular article in the same manner as in Example 1, and a polyimide resin tubular article having a thickness of 30 μm is further formed in the same manner as in Example 2. It was formed and then peeled from the cylinder to obtain a composite tubular article.

The surface resistance of the PFA outer layer in this composite tubular article was 1 × 10 ⁵ Ω · cm / □, and the bonding strength between the PFA outer layer and the intermediate layer was 2H in the pencil hardness test.

Comparative Example The same operation as in Example 1 was carried out except that the intermediate layer was not formed, to obtain a composite tubular article composed of a PFA tubular outer layer having a thickness of 15 μm and a polyimide resin tubular inner layer having a thickness of 30 μm.
The joint strength between the outer layer and the inner layer in this composite tubular article was only 6B or less in the pencil hardness test.

[0057]

EFFECTS OF THE INVENTION The composite tubular article of the present invention is constructed as described above, and since the fluororesin tubular outer layer and the polyimide resin tubular inner layer are joined by the intermediate layer of a specific composition, both layers can be firmly integrated. It has an advantage that it is difficult to cause inconvenience such as peeling of both layers.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a fixing mechanism unit of an image forming apparatus using a heat roller fixing method.

FIG. 2 is a schematic diagram of a fixing mechanism portion of an image forming apparatus using a belt fixing method.

[Explanation of symbols]

 1 Heat Roller 2 Press Roller 3 Transfer Paper 4 Heater 5 Toner 6 Image 7 Peeling Roller 8 Fixing Belt

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiaki Iwamoto 1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation (72) Inventor Toshio Nakajima 1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation

Claims (4)

[Claims] 1. A fluororesin tubular outer layer and a polyimide resin tubular inner layer are joined and integrated via an intermediate layer containing a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, a polyimide resin, an inorganic filler and a surfactant. A composite tubular product. 2. The composite tubular article according to claim 1, wherein at least one of the fluororesin tubular outer layer, the polyimide resin tubular inner layer and the intermediate layer is electrically conductive. 3. The fluororesin tubular outer layer comprises a tetrafluoroethylene-perfluoroalkylvinylether copolymer, or a mixture of the copolymer and a fluororesin other than the tetrafluoroethylene-perfluoroalkylvinylether copolymer, and tetrafluoroethylene-peroxide occupies in the mixture. A composite tubular product having a fluoroalkyl vinyl ether copolymer weight ratio of 10% or more. 4. A fluororesin dispersion is applied to the inner peripheral surface of a cylinder and then heated to form a fluororesin tubular article, and then tetrafluoroethylene-perfluoro is formed on the inner peripheral surface of the fluororesin tubular article. By applying a liquid obtained by dissolving or dispersing an alkyl vinyl ether copolymer, a polyimide precursor, an inorganic filler and a surfactant in a solvent and drying the solution, tetrafluoroethylene-
An intermediate layer containing a perfluoroalkyl vinyl ether copolymer, a polyimide precursor, an inorganic filler and a surfactant is formed, then a polyimide precursor solution is applied onto this intermediate layer, and then heated to form an intermediate layer forming component. As the polyimide precursor and the polyimide precursor in the solution applied on the intermediate layer are imide-converted, the polyimide resin tubular article is integrally joined to the inner peripheral surface of the fluororesin tubular article through the intermediate layer. A process for producing a composite tubular product, which comprises forming the composite tubular product, and then removing the composite tubular product from a cylinder.