JPH0366149B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Purpose and Background) Industrial Application Field The present invention relates to a cylindrical article coated with a thermofluid fluororesin.

There is a lot of demand for such products, including heat-fixing rollers for electronic copying machines, which are undergoing remarkable advances in speed and performance, as well as rolling rollers for plastics, guide rollers for drying dyed fabrics, and dough rollers for the food industry. Numerous articles may be exemplified, such as seating rollers, as well as corrosion-resistant pipes and rods.

BACKGROUND OF THE INVENTION Current technical problems will be explained using a heat fixing roller for an electronic copying machine as an example.

In general, an electronic copying machine forms a toner image on a copy paper by the action of static electricity, passes this image between fixing rollers that are rotating in pressure contact with each other, and fixes the toner onto the copy paper by heating and fusing the toner. In such a fixing method, it is necessary to prevent a phenomenon called "offset" in which the fused toner adheres to the fixing roller and a portion of the attached image adheres to new copy paper.

Therefore, the surface of the heat fixing roller is coated with a fluororesin to prevent toner from adhering to the roller, and the surface of the coating layer is generally coated with an anti-offset liquid such as silicone oil.

Furthermore, in recent years, there has been an increase in the number of heat fixing rollers in which a filler is contained in the fluororesin coating to improve the abrasion resistance and thermal conductivity.

Currently, such fluororesin-coated rollers are made by applying fluororesin powder paint or dispersion paint to an aluminum or aluminum alloy roller.
It is then manufactured by firing.

Problems to be Solved by the Invention Powder coating is mainly performed by electrostatic spraying, but powder coating tends to have a low coating rate and is expensive, and for example, mixed powder of filler and fluororesin When using a paint, the coverage rate of the filler is even lower than that of the fluororesin, so the filler content in the coating layer is lower than the filler content in the mixed powder coating, resulting in a constant coating rate. It is difficult to obtain coatings with filler content.

In addition, dispersion coating inherently makes it difficult to obtain a thick coating layer, and there is a problem in that even in order to obtain a layer of about 50 .mu.m, it requires repeated coatings about three times.

Furthermore, the dispersion of filler into the dispersion coating has a problem in that long-term storage is difficult due to poor dispersibility and dispersion stability of the filler.

As a method other than painting, there is also a roller made by shrinking and fixing a heat-shrinkable tube made of fluorine resin.
Since this roller simply has a close contact between the coating layer and the roller, there are problems in that the tube may be twisted, wrinkled, or even torn if a thin tube is used.

(Structure of the Invention) Means for Solving the Problems In order to solve the problems, the inventors of the present invention have conducted intensive research and have developed a thermofluidic fluorine containing 0 to 30% by volume of filler in a cylindrical article that has been pretreated with a primer. A heat-flowable fluororesin-coated cylindrical article is obtained by shrinking and fixing a heat-shrinkable resin tube at a temperature range from 60°C to less than the melting point of the resin, and further heat-sealing it at a temperature higher than the melting point of the resin, We have found a solution to the aforementioned problem.

The surface of the cylindrical article is previously treated with a primer, preferably with a primer containing a fluororesin, in order to strengthen the fusion bond with the fluororesin. As the primer containing a fluororesin, an aqueous dispersion containing tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer colloid particles and polyamic acid, which is commercially available as a primer for fluororesin paints, is preferably used. Primer treatment can be performed to strengthen the fusion bond with the thermofluid fluororesin by spray coating the surface of the article and then baking. Other desired surface treatments, such as sandblasting, etc., may be used in combination before or after such primer treatment.

The heat-flowable fluororesin, which is the raw material for the heat-shrinkable tube used in the present invention, has a melt viscosity of 1 x 10 ⁴ to 1 x 10 ⁶ poise at its formation temperature, and is a homopolymer of vinylidene fluoride. Included are copolymers, homopolymers and copolymers of chlorotrifluoroethylene, copolymers of tetrafluoroethylene, and the like.

A preferred fluororesin is a copolymer of tetrafluoroethylene and a fluorinated ethylenically unsaturated compound, such as a fluoro(alkylethylene) represented by the following formula: X ₁ (CF ₂ ) _o CX ₂ = CX ₃ X ₄ Fluoro(oxyalkyl ethylene) _: X ₁ (CF ₂ ) _o OCX ₂ = CX ₃ (In the formula, X ₁ , X ₂ , X ₃ and X ₄ are F or H, n is 1
-8, m is 1-5) There are copolymers of fluorinated ethylenically unsaturated compounds and tetrafluoroethylene. Some of these copolymers are Teflon
It is commercially available as FEP, PFA, and EPE (all are trade names of fluororesins manufactured by Mitsui-Dupont Fluorochemical Co., Ltd. and Dupont Company).

Among these tetrafluoroethylene copolymers, copolymers with relatively high melt viscosities, particularly those with a specific melt viscosity of 5 x 10 ⁴ to 1 x 10 ⁶ poise, have high tear strength and are useful in the manufacture of heat-shrinkable tubes and as coatings. This is advantageous in the use of articles with A copolymer with a specific melt viscosity exceeding the above range will not only have insufficient thermal fluidity, which will cause significant disadvantages in forming tubes, but also have poor adhesion properties to metals, etc., which will also be disadvantageous in the production of coating films. It is.

The heat-shrinkable tube can be manufactured by heating the above-mentioned heat-flowable fluororesin tube to a temperature lower than its melting point and applying internal pressure to the tube to cause it to expand in the radial direction. The heat-shrinkable tube is not limited to those produced by the above-mentioned manufacturing method, but may be any heat-shrinkable tube as long as it can be heat-shrinked by heating at a temperature below the melting point.

The heat-shrinkable tube may or may not contain a filler, but the addition of filler improves the moldability of the raw material composition of the heat-shrinkable tube, the heat-shrinkability, strength, and It may be preferable to add a filler for the purpose of improving properties such as abrasion resistance, creep resistance, thermal and electrical conductivity of the coating, as long as the strength of the coating is not significantly impaired.

Types of fillers include powders of metals such as iron, copper, aluminum, chromium, nickel, tin, and zinc, and alloys of these metals, carbon, graphite, glass, alumina, silicon carbide, zirconium silicate, boron nitride, and mica. Examples include inorganic powders such as.

When the above-mentioned filler powder is included, the amount added varies depending on the type of filler and the purpose of addition, but is preferably in the range of approximately 1 to 30% by volume, and 1 to 30% by volume.
If less than 30% by volume is added, the purpose of the addition cannot be fully achieved, and if more than 30% by volume is added, the above-mentioned problems such as poor moldability of the raw material composition occur. In addition, the capacity % in the present invention
is expressed by the following equation.

Volume % = filler weight / filler true specific gravity x 100 / filler weight / filler true specific gravity + resin weight / resin true specific gravity The shape of the powder may be fibrous powder or starchy powder, but it is spherical or close to spherical. Preference is given to using powders in the form of powders.

In addition to the fillers mentioned above, heat-resistant polymers such as polyimide, polyamideimide, polyarylene sulfide, oxybenzoyl polyester, polybenzimidazole, and polysulfone, as well as their precursors, may be mixed into fluororesin to make heat-shrinkable tubes. It is also possible to mix other additives such as pigments and antistatic agents into the fluororesin.

Using the above-mentioned heat-shrinkable tube, shrink the tube in a conventional manner, that is, at a temperature range of about 60°C or higher and below the melting point of the heat-flowable fluororesin, fix the tube to a cylindrical article that has been previously treated with a primer, and further reduce the melting point. The temperature is raised to above and the fluororesin is fused onto the cylindrical article.

The material of the cylindrical article is not particularly limited as long as it can withstand the fusion temperature of the heat-shrinkable tube, and examples include metals and alloys such as iron and aluminum, and ceramics. In particular, aluminum and its alloys are lightweight and have good thermal conductivity, so they are used as heat fixing rollers for electronic copying machines, and steel and stainless steel are generally used for plastic rolling rollers, bread dough sheeting rollers, etc. Ru.

The shrinkage fixing temperature and fusing temperature of the tube vary depending on the type of fluororesin, but in the case of tetrafluoroethylene copolymer, it is preferable to shrink and fix the tube at a temperature in the range of 80 to 250°C. Also, the fusion temperature is
Preferably, the temperature range is from 330 to 400°C. The heating means is not particularly limited as long as it can perform shrinkage fixation and fusion bonding. For example, it is possible to perform shrinkage fixation and fusion bonding continuously with one heating means, but shrinkage fixation can be performed using a hot spray gun. The fusion may be carried out in a furnace.

Example 1 The surface of an aluminum roller was sandblasted, and then MP-902BN (product name: Mitsui
A primer for fluororesin paint manufactured by Dupont Fluorochemical Co., Ltd.; composition: an aqueous dispersion containing copolymer particles of tetrafluoroethylene/barfluoro(alkyl vinyl ether) copolymer and polyamic acid) was spray applied, and baked at 370°C. A primer coating was formed. Next, GF Tube ST (trade name: heat-shrinkable tube made of tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer manufactured by Gunze Co., Ltd.; thickness 50μ) was then placed on the roller.
(melting point: 308°C), and the tube was contracted from one end at a temperature of 150°C using a hot spray gun, and the tube was tightly fixed on a roller. The roller was then placed in an electric furnace and fired at 380°C to fuse the tube onto the roller.

Example 2 A heat-shrinkable tube (thickness: 100 μm) made of tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer containing 15% α-alumina powder and having a melting point of 308°C was placed on a roller coated with a primer in the same manner as in Example 1. The tube was contracted from one end at a temperature of 180° C. using a spray gun, and the tube was tightly fixed on a roller. The roller was then placed in an electric furnace and fired at 380°C to fuse the tube onto the roller.

(Effects) The present invention provides a cylindrical article having a smooth surface and a coating of a desired thickness, and a cylindrical article having a fluororesin coating that does not twist, wrinkle, or tear the coating. A columnar article is provided. Furthermore, it is also possible to obtain cylindrical articles having a fluororesin coating containing a constant filler content, which has been difficult to produce using conventional powder coating and dispersion coating methods.

Claims (1)

[Claims] 1. A heat-shrinkable tube made of a heat-flowable fluororesin containing 0 to 30% by volume of filler in a cylindrical article that has been previously treated with a primer is shrink-fixed at a temperature range from 60°C to less than the melting point of the resin. and a cylindrical article coated with a heat-flowable fluororesin, which is further heat-sealed at a temperature equal to or higher than the melting point of the resin. 2 A heat-shrinkable tube made of a heat-flowable fluororesin containing 0 to 30% by volume of filler is attached to a cylindrical article whose surface has been previously treated with a primer containing a fluororesin.
A cylindrical article coated with a heat-flowable fluororesin according to claim 1, which is shrink-fixed at a temperature range from 60°C to less than the melting point of the resin, and further heat-bonded at a temperature higher than the melting point of the resin. 3 A fluorinated ethylenically unsaturated compound having a specific melt viscosity of 5×10 ⁴ to 1×10 ⁶ poise and containing 0 to 30% by volume of filler in a cylindrical article whose surface has been previously treated with a primer containing a fluororesin. A heat-shrinkable tube made of a thermofluid fluororesin made of a copolymer of and tetrafluoroethylene is shrunk and fixed at a temperature range from 60°C to less than the melting point of the resin, and is further heat-sealed at a temperature above the melting point of the resin. A cylindrical article coated with a heat-flowable fluororesin according to claim 1.