JPH02194876A - Manufacture of double layer tube - Google Patents

Abstract

PURPOSE:To form a smooth fluororesin layer on the outer surface of a polyimide tube by immersing in a fluororesin dispersion the polyimide tube with a rubber-like tube inserted for contact therewith. CONSTITUTION:After inserting a rubber-like tube into a polyimide tube, a pressure is applied to the former tube to bring the outer surface of the rubber-like tube into close contact with the inner surface of the polyimide tube. This is immersed in a fluororesin dispersion to form a fluororesin layer on the outer surface of the polyimide tube. As a result, the inner surface of a double layer tube thus obtained is free from contamination with the fluororesins. The surface roughness of this double layer tube, when compared with the conventional spray coating method, is so low as 0.01-1mu. When it is used for fixing by an image forming device, a glossy, clear image can be obtained.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for manufacturing a multilayer tubular product, and in particular, a multilayer tubular product suitable for use in fixing image forming devices such as copying machines, facsimile machines, and printers. Concerning methods of manufacturing things.

<Prior Art> Conventionally, tubular objects used for fixing in image forming apparatuses such as copying machines, facsimile machines, and printers have been provided with a fluororesin layer on the outer circumferential surface. For example, in JP-A No. 61-95361, a mixture of a polyimide resin precursor solution and conductive fine powder is injected into a cylindrical mold, centrifugally molded while heating, and the inner surface of the cylindrical mold becomes conductive. A method is disclosed in which a non-photosensitive dielectric belt is produced by forming a belt having layers formed thereon, and spray-coating a fluororesin on the surface of the conductive layer to form a dielectric layer.

<Problem to be solved by the invention> However, in the method of spray coating a fluororesin as described above, there are large variations in the thickness of the fluororesin layer formed, and the surface roughness of the fluororesin layer is also 1 μm or more. When using a belt for fixing an image forming apparatus, there is a problem in that it is difficult to obtain a uniform and glossy image.

Means for Solving the Problems> Therefore, the present inventors have conducted extensive studies to obtain a multilayer tubular product formed by forming a fluororesin layer with a uniform thickness.
The present inventors have discovered that by coating the outer peripheral surface of a polyimide tubular material with a fluororesin in a specific manner, a multilayer tubular material that can be suitably used for fixing in an image forming apparatus can be obtained, and the present invention has been completed.

That is, in the method for manufacturing a multilayer tubular product of the present invention, a rubber tubular material is inserted into the inner surface of a polyimide tubular material, and then internal pressure is applied to the rubber tubular material to separate the outer surface of the rubber tubular material and the inner surface of the polyimide tubular material. This is characterized in that a fluororesin layer is formed on the outer surface of the polyimide tube by bringing the polyimide tubes into close contact with each other and immersing them in a fluororesin dispersion.

The polyimide tubular material used in the present invention is usually a polyimide obtained by imide conversion of polyamic acid obtained by a substantially equimolar reaction between an aromatic tetracarboxylic dianhydride or its derivative and an aromatic diamine in an organic solvent. It is made from.

Examples of the aromatic tetracarboxylic dianhydride include pyromellitic acid, 3.3',4.4''-benzophenonetetracarboxylic acid, 3.3',4゜4''-biphenyltetracarboxylic acid, 2,3 .34'-biphenyltetracarboxylic acid, 2,3,6゜7-naphthalenetetracarboxylic acid, 1,2,5゜6-naphthalenetetracarboxylic acid,
1,4,5゜8-naphthalenetetracarboxylic acid, 2,2
゛-bis(3,4-dicarboxyphenyl)propane,
Examples include dianhydrides such as bis(3,4-dicarboxyphenyl)sulfone.

On the other hand, the aromatic diamines include 4,4'diaminodiphenyl ether, 4,4-diaminodiphenylmethane, 3,3°-diaminodiphenylmethane, paraphenylenediamine, metaphenylenediamine, benzidine,
3,3″-dimethylbenzidine, 3.3°-dimethoxybenzidine, 4.4″-diaminodiphenylsulfone,
Examples include 4,4-diaminodiphenyl sulfide, 4,4-diaminodiphenylpropane, and 2,2-bis[4-(4-aminophenoxy)phenyl]propane.

The monomer concentration when synthesizing polyamic acid by reacting the aromatic tetracarboxylic dianhydride and aromatic diamine can be set depending on various conditions, but is usually 5 to 3.
The reaction temperature is set at 80°C or lower, preferably 5 to 50°C, and the reaction is allowed to proceed for about 2 to 10 hours.

The polyamic acid thus obtained is preferably adjusted to have an intrinsic viscosity of 0.degree.

Note that the intrinsic viscosity is a value calculated using the following formula.

The above-mentioned polyamic acid solution can be applied, for example, by dipping the inner peripheral surface of the cylinder, or by supplying the coating solution near one end of the cylinder, and then applying it uniformly by running a bullet-shaped or spherical traveling body, and then heating it. to make a polyimide tube. This heating is carried out to remove the solvent in the solution and convert it into an imide, and to prevent the formation of voids due to the evaporation of the solvent and the evaporation of ring-closing water, etc. generated during the imide conversion, the temperature is about 80 to 180°C. Approximately 20 to 6
Heat for 0 min to remove solvent, then heat to about 250″C~3
A stepwise heating method of heating at 50° C. for about 20 to 60 minutes to effect imide conversion and evaporation of ring-closing water is preferred.

Next, the polyimide tube obtained as described above is extracted from the cylinder, and a rubber tube having an outer diameter slightly smaller than the inner diameter of the tube is inserted. As the rubber tubular material used here, materials made of materials such as styrene-butadiene copolymer rubber, butadiene rubber, polyisoprene rubber, butyl rubber, chloroprene rubber, ethylene propylene rubber, silicone rubber, and fluororubber can be suitably used. .

After the rubber tubular material is inserted, internal pressure is applied so that it comes into close contact with the inner surface of the polyimide tubular material. Methods for making them stick tightly include inserting a rubber tubular object and then pumping air, etc. inside the tubular object to increase the outer diameter, or expanding the tubular object inside the rubber tubing that has been inserted in advance. For example, a method may be used in which a bolt or the like is embedded in order to make the rubber-like tubular material come into close contact with the polyimide tubular material by embedding a bolt or the like and then expanding the rubber tubular material after insertion.

A polyimide tube with a rubber tube inserted and tightly attached,
It is immersed in a fluororesin dispersion to form a fluororesin layer on its outer peripheral surface. As the fluororesin dispersion used here, for example, dispersions such as tetrafluoroethylene, tetrafluoromodified ethylene/hexafluoropylene copolymer, tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer, etc. can be used. .

The viscosity of the above dispersion can be set appropriately by adding a thickener depending on the diameter of the polyimide tubular object to be coated and the thickness to be coated, but it is usually 0.01~
It is preferable to set it within a range of 100 poise for uniformity of coating thickness.

The polyimide tubular material immersed in the fluororesin dispersion as described above is pulled up, air-dried, etc., and the inserted rubber tubular material is removed, heated, dried, and sintered to achieve its intended purpose. It is possible to obtain a multi-layered tubular article.

The resulting multilayer tubular product is a tubular product with a fluororesin layer formed on the outer layer, and the inner layer is made of polyimide tubular material. When the multilayer tubular article obtained in the present invention is used for fixing in an image forming apparatus, the thickness of the fluororesin layer formed as the outer layer is preferably adjusted to a range of 1 to 20 μm. If the thickness is too thin, the effect of the fluororesin layer will be small (,
It is difficult to obtain a clear image, and if it is too thick, the mechanical properties will deteriorate as in the case of a single layer of fluororesin, which is not preferable.

It goes without saying that the polyimide tubular material serving as the inner layer is not limited to a single layer of polyimide resin, and a multilayer tubular material of polyimide resin and other resins can also be used.

<Effects of the Invention> As described above, in the manufacturing method of the present invention, when forming a fluororesin layer on the outer peripheral surface of a polyimide tube, the rubber tube is inserted into the polyimide tube and brought into close contact. Therefore, the inner surface of the resulting multilayer tubular product will not be contaminated with fluororesin. Additionally, compared to the conventional spray coating method, the surface roughness of the multilayer tubular product obtained is 0.01 to 1.
It is extremely smooth with a diameter of μm, preferably 0.1 to 0.5 μm, and when used for fixing in an image forming apparatus, a glossy and clear image can be obtained.

<Examples> Examples of the present invention will be shown below to further specifically explain the present invention.

Example 3.3' Equal moles of 4,4°-biphenyltetracarboxylic dianhydride and 4,4"-diaminodiphenyl ether were added to N-methyl-2-pyrrolidone at a monomer concentration of 20% by weight. The mixture was charged and reacted for 5 hours at a temperature of 20°C to obtain a polyamic acid solution having a viscosity of 35,000 voids (50°C, B-type viscometer) and a solid viscosity of 2.8.

To 100 parts by weight of this solution, 33 parts by weight of N-methyl-2-pyrrolidone was added for dilution, and the mixture was further heated to 50°C to obtain a solution with a viscosity of 1500 voids.

Next, in this solution, a piece with an inner diameter of 123 mm, a wall thickness of 3 M, and a length of 5 mm was placed.
A 0 cm glass tube was immersed, filled with polyamic acid solution and pulled up.

Thereafter, a bullet-shaped bullet having an outer diameter of 122.6 mm was run inside the glass tube at a speed of 20 cylinders/min to uniformly apply the polyamic acid solution to the inner peripheral surface of the glass tube.

This was then heated at 150°C for 60 minutes and at 250°C.
The mixture was heated for 60 minutes to remove the solvent, ring-closing water, etc., perform imide conversion, and then cool to room temperature.

Next, the polyimide tubular article was pulled out by plugging the openings at both ends of the glass tube and pumping air through a small through hole previously provided near the opening of the glass tube. This tubular object is seamless, with an outer diameter of 123 InIO and a wall thickness of 16 μm.
The length was 45 cm (both ears removed).

A rubber tube (made of silicone rubber, outer diameter 122.8 mm, with an expansion bolt installed inside) was inserted into the inner surface of the obtained polyimide tube, and the rubber tube was expanded with the bolt to adjust the outer diameter. was made larger and the rubber tubular material was brought into close contact with the inner surface of the polyimide tubular material.

A polyimide tube fitted with a rubber tube was immersed in a 4-fluorinated modified tyrene/6-fluorinated propylene copolymer dispersion (manufactured by Daikin, ND-1, viscosity 10 centipoise) and pulled up at a speed of 100 mm/min. Air dry 10
After a minute, the rubber tubing was removed.

Next, by sintering at 400°C for 20 minutes, a multilayered tubular article having an outer layer thickness of 7 μm and an inner layer thickness of 16 μm was obtained.

In addition, the surface roughness according to the method of JISBO601 is 0.
It was 7 μm.

When the obtained multilayer tubular article was installed in the fixing section of a copying machine shown in FIG. 1 and a toner image was fixed on paper, a glossy image with good offset property was obtained.

Comparative Example 1 A multilayer tubular article was obtained in the same manner as in the example except that the fluororesin dispersion used in the above example was applied by a spray coating method. The surface roughness of this multilayer tubular material is 1.
The thickness was 6 μm, and the thickness varied.

When this tubular material was installed in the fixing section of a copying machine in the same manner as in the example and the fixing properties were examined, the offset properties were good, but
The resulting image lacked luster.

Comparative Example 2 A multilayer tubular article was obtained in the same manner as in Example, except that a fluororesin layer was formed by powder coating a molding powder of ethylene tetrafluoride/propylene hexafluoride copolymer. Note that the outer layer thickness was 10 μm and the inner layer thickness was 16 μm. The surface roughness of this multilayer tubular material was 2.1 μm.

When this tubular material was installed in the fixing section of a copying machine in the same manner as in the example, and the fixing properties were examined, the offset property was good, but
The resulting image lacked luster.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing a fixing section of a copying machine used in an example.

Claims (2)

[Claims] (1) After inserting a rubber tube into the inner surface of the polyimide tube, internal pressure is applied to the rubber tube to bring the outer surface of the rubber tube into close contact with the inner surface of the polyimide tube, and the fluororesin dispersion 1. A method for producing a multilayer tubular article, which comprises forming a fluororesin layer on the outer surface of a polyimide tubular article by immersing it in water. (2) The method for producing a multilayer tubular article according to claim (1), wherein the outer surface roughness of the multilayer tubular article is in the range of 0.01 to 1 μm.