JPS5838973A - Fixing device - Google Patents

Abstract

PURPOSE:To provide a fixing device which can deal sufficiently with the ruggedness of a backing material, can improve fixability and can maintain sufficient strength and durability with respect to the fixing device which supports unfixed images on the backing material by a prescribed image forming and recording method and fixing the unfixed images on said backing material by using a rotating body having a partial crystalline layer. CONSTITUTION:As a roller for a pressure fixing device, a steel roller provided with a ''Teflon '' layer 11 is used for the roller 1, and a steel roller coated with a soft PVC layer 21 to 1mm. thickness is used for the roller 2. A resin prepd. by compounding 30-50pts. a phthalate plasticizer such as DOP (di-2-ethyl hexyl phthalate) and a small amt. of other agents such as stabilizers, and antistatic agents with 100pts. a resin such as ''GEON 101EP or 103EP '' is used for the soft PVC. Said resin is coated by extrusion on the steel roller of 25mm. diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixing device that supports an unfixed image on a support material by a predetermined image forming and recording method and fixes the unfixed image on the support material. Several fixing methods have been proposed, but the two that are in practical use commercially are the heating power method and the pressure method. This dissolves and fixes the toner.

On the other hand, the pressure method uses the pressure of the fixing roller to press the toner, and since it does not require heating, it can be operated immediately, and has recently been praised as a method suitable for high-speed copying without the risk of fire. ing.

Further, the surface of the fixing roller in this system is made of metal, plastic, or the like.

An example of this is the 46th Special Publication, which is one of the pressure fixing devices.
As described in Newsletter No. 15876, some fixing rollers 2 with a nylon-like surface are used, especially when fixing toner particles on a support material with an uneven surface like paper. This has the effect that a certain amount of pressure can be applied by its elastic deformation.

However, even if the fixing roller described above is used, it is difficult to apply uniform pressure to the entire uneven surface of the support material. Generally, the unevenness of the support material is 10 to 100μ (10 to 100μ in detail), and in order to cause the fixing roller to deform by 10 to 100μ to match the unevenness, a nylon layer is required on the surface. However, even with such a thickness, there is virtually no improvement in fixing performance, and if you try to increase the amount of deformation by increasing the pressure, If the deformation rate is too high, the nylon surface layer will be destroyed.Furthermore, in a fixing roller with such a relatively thick surface resin layer, if you try to reduce its diameter, it will not have sufficient mechanical strength. Therefore, a fixing roller with a large diameter is inevitably required.

On the other hand, if a surface layer with a relatively small elastic constant such as silicone rubber or urethane rubber is used, the thickness of the surface layer can be reduced from 0.5 to 2.0.
- degree, and a roller with a relatively small diameter can provide sufficient mechanical strength. However, with such a roller having a rubber surface layer, the gap between the nip portions of the fixing roller becomes wide, and 9) it is not possible to apply sufficient pressure to the toner on the toner support material.

In view of the above-mentioned problems, the present invention solves the above-mentioned problems, and provides a rotating body that can sufficiently cope with the uneven surface of the support material, improve fixing performance, and maintain sufficient strength and durability. An object of the present invention is to provide a fixing device having the following.

Hereinafter, the present invention will be explained with reference to a pressure fixing device. A pressure fixing device made of the following 4 m material was applied to a fixing roller under the same conditions such as surface layer thickness, applied pressure, compressive elastic modulus, etc. and compared. The following differences in effectiveness arose.

A first K amorphous material, for example, a fixing sheet having a polystyrene/surface layer, is extremely brittle to a stress exceeding the yield point of its elastic deformation and undergoes brittle fracture. Secondly, rollers made of materials with a high degree of crystallinity, such as polypropylene, have a degree of crystallinity exceeding 9 (l), resulting in a decrease in impact strength and poor durability, and are resistant to stress exceeding the yield point. It's fragile.

Thirdly, a roller made of a partially crystalline material such as a polyvinyl chloride surface layer, and fourthly a roller made of a crystalline material with a relatively low degree of crystallinity, such as a low-lf polyethylene surface layer, are used. The case of the case did not have the brittleness like the case of the case above, and sufficient durability was obtained even when stress exceeding the yield point was applied. Furthermore, if the surface thickness is 1 to 2μ and the compressive modulus is 5 to 200 (-), then a deformation value of 10 to 100μ can be obtained to sufficiently follow the unevenness of the paper for a pressure of 20 to 2004/-j. , the fixability was further improved.Hereinafter, the term "partial crystallinity" in the present invention will be used as a general concept of crystallinity with a low degree of crystallinity.

As mentioned above, when using resin for the pressure roller surface, accidents other than normal use, such as double feeding of the toner support or foreign objects such as boat clips being fed together with the toner support, may occur. When the surface of the fixing roller is damaged, it is necessary that the surface of the fixing roller has a certain degree of self-healing property against the pressure roller.

Here, the self-uqM property is obtained by, when a scratch or dent occurs on the surface of the pressure roller, the plastic around the scratch or dent is fluidized and deformed due to viscoelasticity as the roller rotates. Such excellent effects are remarkable in the third partially crystalline material or the fourth polymer resin with low crystallinity.

As a material suitable for the above-mentioned surface layer having a low degree of crystallinity, it is more preferable that the material has durability against relatively large compressive deformation and has good self-healing properties. For this example, polyamide resins with relatively low crystallinity are suitable.

In addition, on the second side of the rotating body such as the fixing roller mentioned above,
In addition to providing a surface layer made of a single material, a similar partially crystalline layer may be provided on the upper surface of the composite layer. Furthermore, by processing those that do not satisfy the conditions from IkvJ,
It may be partially crystalline. As an example of this, a polycondensation product of terephthalic acid and trimethylmexamethylene diamine, which is known as amorphous transparent nylon, becomes partially crystalline or has a low degree of crystallinity, and the surface layer of the pressure fixing roller is difficult to bind. It is in good condition.

Polyethylene is generally known as a typical crystalline polymer resin, and many have a high degree of crystallinity, but those with a degree of crystallinity of 70% or less are among the lowest among the same resins and are therefore effective for the present invention. It is a book with a density of 0.91.
~0.93 low density polyethylene is good as a pressure fixing roller surface material.

Partially crystalline polymers or crystalline polymers with a low degree of crystallinity can be used to support the toner with a relatively thin surface resin layer, which can apply uniform pressure to the toner and can also be expected to have self-healing properties. Among the molecules, polyvinyl chloride has a number of advantages such as solving the conventional drawbacks and improving fixing properties, and polyvinyl chloride has particularly good properties.

Polyvinyl chloride is a partially crystalline polymer that can undergo necking and deformation even when subjected to stress exceeding its yield point. In addition, polyvinyl chloride has a composition that can be used as a surface resin for zero-fixing rows, which can be used to create materials with elastic modulus over a wide range from semi-hard to soft by using a liquid plasticizer such as DOP-ethylhexyl phthalate. No. 3
Contains a plasticizer of 0 to 40 mm, which is generally called soft, is best, and is coated on a metal roller to a thickness of 0.3 to 2 mm by extrusion molding, sludge molding, dipping, etc.
By applying a certain amount of coating and using it, a pressure fixing device can be constructed which compensates for the unevenness of the toner support material and applies a uniform pressure to the toner image.

Partially crystalline polymer resins such as polyvinyl chloride have never been used as pressure fixing rolls, but as will be explained later, comparable fixing performance can be achieved with lighter pressure compared to pressure fixing devices using metal rolls. As a result, it is possible to prevent the generation of transparent gloss and curl caused by pressurizing the toner support, which were disadvantages of conventional pressure fixing devices, and to provide high-quality fixed images. The following is a detailed explanation of the present invention with reference to the drawings. In FIG. 1, 1 is a fixing roller, and 2 is a pressure roller, each of which has a bolt 5 on the opposite side of the axis 0, and a pressurizing roller provided between the bolt head and the side plate 3 and containing a compression spring 6. The roller 2 is rotated by an electric motor via a gear train (not shown) by the elastic force of the spring 6, and the roller 2 is rotated by the frictional force.

The paper P supporting the toner image, such as photosensitive paper or transfer paper, is held between the pair of rollers 1 and 2 so that the toner image surface is in pressure contact with the roller 1, and is conveyed in the direction of the arrow by the rotation of the pair of rolls. be done. Here, since the pair of p-jers are pressed against each other by a pressurizing means (bolt 5.degree. compression spring 6), the paper PK pressure on the tonaha is constant.

As the roller of such a pressure fixing device, a steel roller provided with a Teflon layer 11 is used as the roller 1,
The roller 2 has a soft vinyl chloride layer 2 on the steel roller. Use one coated with one cod thick to make a round shape. The fixing roller 1 may be a steel roller coated with a release agent such as silicone oil to prevent offset. As soft vinyl chloride, resin 1 such as Zeon 10IEP or 103EP
Made of steel with a diameter of 25 cm by extrusion processing using a mixture of 30 to 50 parts of a phthalate plasticizer such as DOP (di-2-x tylhexyl phthalate) and a small amount of other stabilizers and antistatic agents per 00 mK. Coated onto a roller.

chloride? In addition to the extrusion process described above, coating or dipping with vinyl chloride paste or a heat-shrinkable chain made of vinyl chloride may be used as a coating method for the rubber. When the image is fixed, even if a linear pressure of 15cm/cm is applied, if the conventional rollers 1 and 2 are made of steel, the image will not be fixed in the recesses of the paper. It is possible to obtain good fixing performance by applying a light linear pressure such as 10/'cI11 to the toner image, and because the pressure acts on the undetermined image in the concave portion in a way that matches the texture of the paper. Ta.

Furthermore, when a conventional steel roller and a particularly excellent polyvinyl chloride coated roller of this example were compared under the same pressure application, in this example, the toner support material became glossy or transparent, and its curling phenomenon was observed. These drawbacks could be significantly reduced. This is thought to be mainly due to the fact that the nip area of the polyvinyl chloride-coated roller slightly increases and the pressure at the nip area decreases. Due to this property (which is thought to be due to the nature of the film), it was possible to prevent the occurrence of gloss, which is unavoidable with conventional pressure fixing, especially even in small black areas.

In the present invention, it is preferable for the above-mentioned partially crystalline layer thickness to be 5 mm or less in order to improve durability, and it is especially preferable to make the layer thickness around Klm thick.Applicable to both rotating bodies. You may do so.

Although the present invention has been described above with reference to a pressure fixing device, the present invention can also be applied to a rotating body used in a heat fixing device.
Since the pressure applied to the uneven parts of the support material can be applied evenly and over the entire surface, the amount of heating that was previously required can be reduced.
It has the effect of reducing the wait time during fixing, greatly improving fixing efficiency and performance, and achieving faster fixing more reliably.

As described above, the present invention solves the conventional drawbacks, significantly improves fixing performance, and provides a fixing device with excellent durability.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of one embodiment of the present invention. 1 is a fixing roller s, 11 is a Teflon layer, 2 is a suppression roller, and 21 is a vinyl chloride layer.

Claims (1)

[Claims] A fixing device that fixes a support material supporting an unfixed image by sandwiching and conveying it between rotating bodies, the fixing device comprising a rotating body having a partially crystalline layer.