JPH04298778A - Fixing roller - Google Patents

Abstract

PURPOSE:To satisfy the release property, electrical conductivity and wear resistance of a roller surface and to obtain bright fixed images by providing a conductive fluorinated hydrocarbon resin layer via a conductive primer via a metallic arbor and providing a specific thin releasable film thereon. CONSTITUTION:A primer prepd. by properly adding a conductive filler to a general-purpose primer of a fluorinated hydrocarbon resin base or the like is used as the conductive primer and the amt. of the filler to be added is preferably about <=5wt.% (by solid content). This conductive primer is applied on the arbor and after the primer is predried, the conductive fluorinated hydrocarbon resin layer is formed thereon. Further, the releasable film formed by applying a fluorinated hydrocarbon resin contg. glass fibers and baking the resin is provided thereon at <=10mum thickness. The amt. of the glass fibers to be added is specified to 1 to 10% of the total weight of the releasable film. The fiber length of the glass fibers is preferably confined to <=20mum in terms of the uniform dispersion in the fluorinated hydrocarbon resin. The sufficient electrical conductivity is obtd. in this way and the wear resistance is improved while the release property of the fluorinated hydrocarbon resin is well maintained without impairing the electrical conductivity of the lower layer.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a fixing roller used in a fixing section of an electrophotographic copying machine.

0002

2. Description of the Related Art Generally, a fixing section of an electrophotographic copying machine is provided with a pair of rollers, at least one of which is equipped with a heat source, and when a conveyed paper passes between these rollers, a toner image is heated and pressurized. A method in which the image is fixed after being fixed is often used.

The characteristics strongly required of the fixing roller used in such a system are to prevent offset phenomenon to produce a good fixed image, and to provide antistatic performance to prevent paper from wrapping. The outer surface of the roller must have sufficient abrasion resistance to withstand continuous use.

On the other hand, conventional fixing rollers have, for example, coated the outer surface of the roller with polytetrafluoroethylene (PTFE) resin containing conductive carbon (U
SP4179601), or coating the core with PTFE resin via a primer containing conductive carbon (Japanese Patent Application Laid-Open No. 150869/1983) has been proposed. However, since the former contains conductive carbon on the outer surface of the roller, the surface volume resistivity is small and the antistatic performance is good, but it has the disadvantage that the mold release property and abrasion resistance are significantly reduced. . Also,
Since the outer surface of the roller is coated with PTFE resin, the latter has good mold releasability, but has problems in that sufficient conductivity cannot be obtained and, like the former, wear resistance is low.

[0005] Therefore, in the PTFE resin on the outer surface,
A method has also been proposed in which a metal-based conductive filler is added to improve wear resistance and conductivity at the same time (
Japanese Patent Publication No. 58-23626) discloses that in a roller having this structure, the excellent mold releasability of the PTFE resin itself deteriorates, and the conductivity does not improve much. In this way, conventional rollers all have advantages and disadvantages,
A material that satisfactorily satisfies the three requirements of mold releasability, electrical conductivity, and abrasion resistance has not yet been obtained.

[0006]

[Problems to be Solved by the Invention] In view of the above problems, the present invention aims to provide a clear fixed image by fully satisfying the three properties of releasability, conductivity, and abrasion resistance on the roller surface at the same time. The purpose of the present invention is to provide a durable fixing roller capable of continuous sheet feeding.

[0007]

[Means for Solving the Problems] The present invention provides a conductive fluororesin layer on a metal core shaft via a conductive primer, and further coats and bakes a fluororesin containing glass fibers on the conductive fluororesin layer. The present invention relates to a fixing roller characterized by being provided with a moldable film. The conductive primer and conductive fluororesin layer are laminated to provide sufficient conductivity, and the thin coating of fluororesin containing glass fibers allows the fluororesin to be released from the mold without impairing the conductivity of the underlying layer. Abrasion resistance can be significantly improved while maintaining good properties.

[0008] As the conductive primer, a general-purpose primer such as a fluororesin-based primer to which a conductive filler (eg, conductive carbon) is suitably added can be used. The amount of conductive filler added is 5% by weight based on the primer.
(Solid content ratio) The following is desirable. If more than this is added, the adhesion performance as a primer may be impaired. Note that, before applying the primer on the metal core shaft, if the surface of the metal core shaft is previously degreased and cleaned, and then roughened by sandblasting or the like, the adhesive force of the primer will be further improved. In addition, the coating thickness of the primer can be set appropriately from the viewpoint of adhesive strength and conductivity of the primer, and is several μm thick.
m to several tens of μm.

In the present invention, a conductive fluororesin layer is formed on the area where such a conductive primer is applied and pre-dried. Examples of the conductive filler include conductive carbon, metal fibers, conductive tin dioxide, antimony trioxide, and potassium titanate, and these can be used in an appropriate mixture. As a fluororesin, PT
A dispersion of FE resin is preferred, and the conductive filler is added and dispersed therein and coated on the conductive primer layer by a conventional method such as coating or dipping.

[0010] The present invention is characterized in that a releasable film formed by applying and baking a fluororesin containing glass fibers is provided directly on the conductive fluororesin layer. The reason why it is provided directly above the conductive fluororesin layer is to prevent the conductive performance of the roller surface layer from being impaired as much as possible. Therefore, the thickness of this releasable film greatly affects the conductivity of the roller, and is preferably 10 μm or less, more preferably 7 μm or less.
It is preferable that the thickness be less than μm.

The amount of glass fiber added is 1 to 10% by weight, more preferably 1 to 8% by weight, based on the total weight of the releasable coating. When the amount is more than 10% by weight, the surface condition of the resulting roller deteriorates, the offset resistance becomes significantly worse, and no improvement in abrasion resistance is observed. Moreover, if it is less than 1% by weight, the effect of wear resistance will be small. The fiber length of the glass fiber is preferably 20 μm or less from the viewpoint of uniform dispersion in the fluororesin.

In addition, as the fluororesin, known fluororesins such as PTFE resin and PFA resin can be used, but as mentioned above, this releasable coating needs to be a thin film of 10 μm or less. Pinholes are likely to occur, and the roller surface may not be uniform. Therefore, from the viewpoint of preventing the occurrence of pinholes, it is particularly desirable to use PTFE resin, which has a high melting point and low resin fluidity.

[0013]Fibers of graphite, titanium dioxide, potassium titanate, etc. may be used in combination with glass fibers as appropriate for the mold release coating.

[0014]

[Example] An example of the present invention will be described. (below,
All "% by weight" indicate solid content ratio. ) A fluororesin primer containing 2% by weight of carbon black was applied to a thickness of 10 μm on an aluminum core shaft with an outer diameter of 40 mm that had been previously degreased, washed, and sandblasted, and dried. PT containing 6% by weight of carbon black on top of this
A conductive fluororesin layer with a thickness of 10 μm is formed by applying and firing FE resin, and on top of that, glass fibers (average fiber length: 10 μm) are formed.
A fixing roller of the present invention was manufactured by applying and baking a PTFE resin containing 3 μm thick to form a releasable film having a thickness of 3 μm.

Abrasion resistance (abrasion loss (mg) after passing 40,000 sheets) and offset resistance when the amount of glass fiber in the release coating is 5, 10, 20, and 30% by weight, respectively. (Number of sheets passed until the first offset occurs) was investigated and found as follows.

Glass fiber amount (weight %) 5
10 20 30◎ Wear loss (mg) 21
17 20 33◎ Offset resistance (sheets) 200,000 80,000
20,100 ◎ Also, when the thickness of the releasable film was set to 3, 7, 10, and 13 μm, respectively, the volume resistivity (Ωcm) on the roller surface was measured, and the results were as follows. Note that the volume resistivity value of the surface of the conductive fluororesin layer when no releasable film is provided is 108.
It was 4 Ωcm.

Thickness of releasable film (μm) 3
7 10 13◎ Volume resistance value (Ωcm) 108.5 10
8.7 109.9 1014◎Comparative Example As a comparison, a roller was manufactured in the same manner as in the example except that 5% by weight of carbon black was blended instead of glass fiber. The wear loss of the obtained roller after passing 40,000 sheets was 7.
3 mg, and offset resistance was 30,000 sheets.

[0018]

[Effects of the Invention] As described above, the fixing roller of the present invention sufficiently satisfies the three properties of releasability, conductivity, and abrasion resistance on the roller surface at the same time, and the fixed image is clear and a large amount of paper can be passed continuously. It has excellent durability.

Claims (1)

[Claims] Claim 1: A conductive fluororesin layer is provided on the metal core shaft via a conductive primer, and a releasable film is further provided on the layer by coating and baking a fluororesin containing glass fibers. A fixing roller.