JPS6136778A - Coating material of heat roll for heat fixing - Google Patents

Abstract

PURPOSE:To obtain a fixing roll which prevents offsetting without coating of a release agent, has high mechanical strength and heat conductivity and can supply heat with good efficiency by using perfluoroalkyl functional silane having a CF3 group at the terminal as a coating material for a heat roll for heat fixing. CONSTITUTION:The coated heat roll is obtd. by dipping a metallic core material roll into an org. solvent soln. such as toluole of the perfluoroalkyl functional silane having the CF3 at the terminal, for example, perfluoroalkyl functional silane expressed by the formula then pulling up the roll and drying and removing the solvent. The functional group such as amide group, sulfonic acid group or carboxy group of the silane contributes to an increase in the adhesive strength to the metallic core material and the strength of the film. The film is as thin as about the thickness of a monomolecular film and can prevent the offsetting of a toner without coating of the release agent and therefore the fixing roll for an electrophotographic copying machine which has high heat conductivity and can efficiently supply heat is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a coating material for a heat roll used in thermal fixing of toner.

Conventional technology The toner fixing methods used in electrophotographic copying machines include heat,
Although it is broadly divided into methods that use pressure and solvents, a heat fixing method is generally adopted from the viewpoint of fixing efficiency and economical efficiency. Furthermore, among the heat fixing methods, the most common is a fixing method using a heat roll, which has high thermal efficiency, excellent safety, and provides stable fixing performance over a wide range from low-speed machines to high-speed machines. The properties required for this heat roll include not only heat resistance but also mechanical strength and mold releasability.

Heat resistance is necessary because heat rolls are used at temperatures generally between 60 and 210°C, and mechanical strength is necessary because two rolls are used under pressure against each other.
Furthermore, releasability is necessary to prevent toner transfer to the heat roll, that is, to prevent offset phenomenon. In order to satisfy these required characteristics, the surface of conventional heat rolls has been coated with a low surface energy material such as tetrafluoroethylene resin, fluorine rubber, or silicone rubber. However, even with these coating materials, the female part properties of the toner are insufficient, and furthermore, it is necessary to apply a release agent such as silicone oil to the roll on the side that comes into contact with the toner. Moreover, the conventional ah
Materials require a certain layer thickness for strength, and rubber-based materials in particular need to be thick to obtain a nip width, which impedes heat conduction and increases warm-up time, or when making continuous copies. There were problems with heat supply, such as a drop in roll surface temperature.

Purpose The weight of the present invention is to prevent toner offset without applying a release agent, and to maintain the desired mechanical strength, the coating layer can be made as thin as a monomolecular film, and therefore efficient heat supply is possible. An object of the present invention is to provide a coating material for a heat roll for heat fixing.

It consists of a fluoroalkyl-functional silane.

This 4-fluoroalkyl-functional silane is a compound represented by the following general formula, is known as a type of clan coupling agent, and is available as a commercial product.

General formula % formula % (R: hydrocarbon chain, Y: hydrolyzable group such as alkokene group,
The length of the perfluoroalkyl group is preferably 7 or more carbon atoms. In addition, a core material roll (metal) is used for the hydrocarbon chain.
In order to further increase the adhesive strength and mechanical strength, a polar group such as an amide group or a sulfonamide group may be introduced.

When coating the roll surface with the above-mentioned coating material, it is desirable that the thickness be as thin as possible from the viewpoint of thermal efficiency, and ideally a monomolecular film is preferable.

To form a monomolecular film, dissolve the fluoroalkyl-functional silane in a solvent with a surface tension higher than the γC (critical surface tension) of the monomolecular layer of the ξ-70 fluoroalkyl-functional silane, and immerse a roller core in this. (At this time, the silane is oriented and adsorbed to the surface of the core metal.) This method is easier than the conventional coating and polishing method, and has significant cost advantages from both the equipment and manufacturing standpoints.

As the material of the core material roll, usual materials, ie, metals such as aluminum, copper, and stainless steel, are used.

Examples of the present invention are shown below.

Example: Perfluoroalkyl-functional silane C, F, C0NHCH,OHN (CHt)s with an amide group introduced into the hydrocarbon chain
S l (OCHs) #COC,F,I+ 30Jl was dissolved in 30ml of pure toluene, and a stainless steel roll was dipped in the solution and then pulled up.Noq-fluoroalkyl functional silane was adsorbed on the roll surface. I was forced to lie down. The resulting heat roll is called Roll A.

Example 2 Nozo-fluoroalkyl-functional silane with a sulfonamide group introduced into the hydrocarbon chain C, F, So, N
HCFI, CH, N(CH,)s S i (OCT(
,)3SO2CHFl? A heat roll was made in the same manner as in Example except that . This is called Roll B.

When comparing the offset temperatures of these rolls A and B with conventional tetrafluoroethylene resin-covered heat rolls (hereinafter referred to as roll C) and Hikuricorn rubber covered heat rolls (hereinafter referred to as roll D), roll D <roll The rolls were A and B. Therefore, it can be seen that the releasability of the heat roll made of the covered material of the present invention is superior to that of the heat roll made of the conventional coating material.

Regarding the decrease in roll surface temperature during continuous copying, Tehalol D>Roll C>Rolls A and B. From this, it can be seen that the exposed layers of Rolls A and B were made of monomolecular films, and as a result, the thermal conductivity was increased.

As described above, the coating material of the present invention can be made as thin as a monomolecular film as a coating layer while maintaining the desired mechanical strength, and therefore has high thermal conductivity and can efficiently supply heat. Therefore, it is possible to shorten the warming-up time of the heat roll and prevent a drop in the roll surface temperature during continuous copying.

Of course, toner offset can also be prevented without applying a release agent.

Claims (1)

[Claims] 1. A coating material for a heat roll for heat fixing made of a perfluoroalkyl functional silane having a CF_3 group at the end.