JPS63289573A - Heat fixing roll - Google Patents

Abstract

PURPOSE:To improve paper feedability so that wrinkling is prevented and fixability is improved by laminating a bonding layer, insulating layer and exothermic layer in this order on the outside surface of a cylindrical arbor and further, providing a heat resistant elastic material layer and release layer integrally to the outside thereof. CONSTITUTION:The bonding layer 22, the insulating layer 23 and the exothermic layer 24 are laminated in this order on the outside surface of the cylindrical arbor 21 consisting of a metal or alloy having good thermal conductivity and further, the heat resistant elastic material layer 27 and the release layer are integrally provided on the outside thereof. Since the elasticity is imparted to a heat fixing roll 2, the paper feedability is improved and the wrinkling is prevented. In addition, the uniform contact between the toner image on a carrier and the roll surface is attained and the fixability is improved. The surface hardness of the heat fixing roll in excess of 80 deg. is inadequate in this case, since the width of the nip formed between the heat fixing roll and a press roll is insufficient and the fixability of the toner image is degraded even if the prescribed press-contact force is exerted to both the rollers in the state of the rolls facing each other.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is used for fixing a toner image formed on paper or other carrier in an image forming apparatus such as an electrophotographic apparatus or an electrostatic printing apparatus. The present invention relates to a heat fixing roll constituting a heat fixing device.

[Conventional technology]

A fixing bag in an image forming apparatus is a heat-resistant mold release material such as tetrafluoroethylene or perfluoroalkoxy resin on the surface of a thermally conductive metal core equipped with a heat source such as an infrared lamp, halogen lamp, or nichrome wire inside. A heat roll type heat fixing device in which a heat fixing roll having a heat-resistant elastic layer and/or a heat-resistant elastic layer such as silicone rubber and a pressure roll having two surfaces covered with a heat-resistant elastic layer are disposed facing each other. Some devices are known (for example, see Japanese Patent Publication No. 54-19347 and Japanese Patent Publication No. 57-46794). However, in such a type of heat fixing device, the heat fixing roll does not reach the temperature required for fixing. It will take time to do so.

The disadvantage is that the efficiency of heat transfer from the heat source is low.

In order to improve this problem, a type of heat fixing roll having a structure in which a heat generating layer is directly provided on the outer surface of the heat fixing roll has also been proposed.

FIG. 3 is a partially sectional side view showing a state in which a conventional heat fixing roll and a pressure roll are in pressure contact with each other. In the figure, reference numerals 1 and 2 denote a pressure roll and a heat fixing roll, respectively, which are formed so that their axes are substantially parallel and rotatable in the direction of the arrow, and nine rolls are arranged in pressure contact with each other. In the conventional type, for example, the pressure roll 1 has a heat-resistant elastic layer 1 made of silicone rubber with a hardness of 45 to 55 degrees on the surface of a core metal 1) made of a material with good thermal conductivity such as aluminum alloy or iron.
On the other hand, the heating and checking roll 2 is bonded to the outer surface of a hollow cylindrical core metal 21 (which may be solid) made of a material with good thermal conductivity such as aluminum alloy, stainless steel, or iron. Layer 22. Insulating layer 239 Heat generating layer 24. insulation 1'1
25 and a heat-resistant release layer 26 are laminated in this order. The heat-resistant mold release layer 26 is made of, for example, tetrafluoroethylene resin (PTFE), perfluoroalkoxy resin (p
FA) etc.

In the above heat fixing device, when fixing the toner image formed on the carrier, first, power is supplied to the heat source to heat the surface of the heat fixing roll 20 to the temperature required for fixing, and then the heat fixing roll 2 and pressure are applied. The toner image can be fixed on the carrier by pressing the roll 1 into contact with the roll 1 and rotating it, and passing the carrier carrying the toner image between the two rolls.

[Problem that the invention seeks to solve]

For example, when an address is printed on an envelope using the heat fixing device described above, wrinkles occur on the envelope, which not only causes the envelope to become curved or deformed, but also causes the printed address to be divided by the wrinkles, and in extreme cases, There are problems such as inability to decipher or read. In other words, envelopes have at least two overlapping parts due to their structure, and depending on the part or overlapping part, the gluing can be triple or quadruple, which increases the maximum paper thickness and causes mutual sliding movement in the overlapping parts. This is a unique phenomenon caused by this phenomenon, and is a problem that is not experienced in the case of normal copying.

To explain the above problem in more detail, there is a difference in hardness between the pressure roll 1 and the heat fixing roll 2.

As shown in FIG. 3, at a pressure contact portion 3 between the pressure roll 1 and the heat fixing roll 2, the surface of the pressure roll 1 forms a concave surface. For this reason, when a carrier such as paper (not shown) carrying a toner image is fed in the direction of the arrow, the carrier is first bent at the entrance 3a of the pressure contact portion 3 with the upper part concave.
Next, it is bent at the press-contacting part 3 so that the lower side is concave, and then it is bent again at the outlet 3b of the press-contacting part 3 so that the upper side is concave. On the other hand, when the carrier has double or more overlapping parts like an envelope, the pressure contact part 3
It is presumed that the repeated bending action causes sliding movement between the upper and lower constituent parts, or the difference in movement speed due to the difference in envelope thickness also causes a speed difference between the upper and lower parts of the envelope, causing wrinkles.

As an example of the above-mentioned measures, in the case of envelope fixing, measures have been proposed such as lowering the fixing pressure than the fixing pressure suitable for fixing plain paper (Japanese Patent Application Laid-Open No. 61-294475), but the structure of the recording device There are problems such as complexity, and it is not practical.

In order to prevent bending and wrinkling when fixing thick paper such as business card paper and postcards, a fixing device was developed in 1973, which was constructed so that the pressure deformation rate of the surface portion of one roll was the same or close to that. It is disclosed in Japanese Patent No.-98226. However, this fixing device has a structure in which both rolls are brought into "light pressure contact" in order to make the deformation amounts of the pressure contact portions of both rolls equal or similar to each other, and therefore sufficient fixing performance cannot be obtained.

The present invention solves the problems existing in the above-mentioned prior art, has high paper feeding performance, and does not cause wrinkles even when the carrier is made up of multiple layers, such as envelopes. An object of the present invention is to provide a heated window layer roll capable of fixing toner images.

[Means for solving problems]

In order to solve the above problems, five aspects of the present invention are provided.

A bonding layer, an insulating layer, and a heat generating layer are laminated in this order on the outer surface of a cylindrical core made of a metal or alloy with good thermal conductivity,
Furthermore, a heat-resistant elastic layer and a release layer are integrally provided on the outside thereof. This technical method was adopted.

In the present invention, if the surface hardness of the heat fixing roll exceeds 80°, the nip width formed between the nine rolls will be insufficient even if a predetermined pressing force is applied while facing the pressure roll. This is disadvantageous because the fixability of the toner image deteriorates. In this case, even if the pressure is increased to secure the nip width,
This is undesirable because it causes deformation of the toner image carrier and causes wrinkles and other undesirable phenomena.

Next, the thickness of the heat-resistant elastic layer provided on the heat fixing roll is IN
If it is less than 80°, it will be difficult to ensure the roll surface hardness to be 80° or less, and it will not be possible to contribute to the formation of the nip width by elastic deformation of the heat-fixing roll, which is disadvantageous. On the other hand, if the thickness exceeds 2 mm, not only will the temperature distribution in each part of the heat fixing roll be uneven, but it will also inhibit heat conduction, causing unforeseen accidents such as overheating of both ends, which are non-sheet passing parts. This is not desirable because it causes

Furthermore, the thermal conductivity of the material constituting the heat-resistant elastic layer provided on the heat fixing roll is 0.2 x 10-"cal/cm-s.
If the temperature is less than ec.° C., the heat conduction effect within the heating fixing roll will be insufficient, which will not only result in uneven temperature distribution but also cause local heating, which is disadvantageous. The above thermal conductivity is 0.6 XIO cal/cm-sec・℃
It is preferably greater than or equal to 1.5×, more preferably 1.5 ×
10-'cal/cm HSec H'c or more. The thermal conductivity can be adjusted by mixing a good heat conductive substance 2 such as carbon black or a metal oxide such as titanium oxide into the heat-resistant elastic layer.

However, when the above-mentioned good heat conductive substance is mixed, the hardness of the heat fixing roll increases, so the amount of the good heat conductive substance added is preferably determined within a range that does not increase the hardness more than necessary.

[Effect]

As mentioned above, by imparting elasticity to the heat fixing roll, paper feeding performance is improved, wrinkles are less likely to occur, and the toner image on the carrier and the roll surface come into uniform contact. It is thought that fixing properties are improved.

In addition, by reducing the difference in hardness between the pressure rolls that form a pair, a tab is formed at the pressure contact area of both rolls.

That is, it is thought that by making the passage portion of the toner image carrier substantially flat, there is an effect of preventing wrinkles from forming on the toner image carrier.

〔Example〕

FIG. 1 is a partially sectional side view showing an embodiment of the present invention,
Identical parts are designated by the same reference numerals as in FIG. 3 above. In FIG. 1, the core bar 21 constituting the heat fixing roll 2 is made of a material with good thermal conductivity, such as an aluminum alloy, as described above, and the wall thickness of the hollow cylinder is 0.
．． It is best to have 5 to 3 dragons. Next, the bonding layer 22 is formed to have a thickness of 20 to 100 μm by coating or thermal spraying, for example, Ni-A1-Mo alloy fine particles. The material for forming the insulating layer 23 is Aj! zOs, Allz
Os.

Mg O, Y! Insulating ceramics made of Os, SiOx, ZrOx or mixtures thereof can be used, e.g. by plasma spraying to a thickness of 50 mm.
~500pm, preferably loo~3o.

To form the 9th order heat generating layer 24 formed in μm.

For example, Aj'z Ov, Aft 03 ・Mg O
A mixture of fine particles of an insulating ceramic such as Ni-Cr and fine particles of a conductive material such as Ni-Cr can be used. Similar to the above, plasma spraying means can be applied, and the thickness is 50 to 250 μm, preferably 60 to 80 μm.
It is better to Furthermore, similar to the pressure roll 1, on the outside of the heat fixing roll 2.

The heat-resistant elastic layer 27 is integrally provided as a member to be adhered to, and as a constituent material, silicone rubber, fluororubber, a mixture of fluororubber and fluorine resin, etc. can be used. The thickness should be 1 to 2 cm thick. The heat fixing roll 2 was formed to have an outer diameter of 31 m.

With the above configuration, fixing was performed by contacting with pressure at a pressure of 1.2 kg/am. The fixing speed was 166 mm/sec, and the fixing temperature was 180°C. In this case.

Using envelopes as toner image carriers in combination with various combinations of silicone rubber hardness and rolls coated with PFA resin, the state of wrinkles on 100 envelopes was evaluated for each combination. did.

The results are shown in FIG. In this case, the surface hardness of the roll (
A type spring type hardness (JIS K 6301) is a value measured using a commercially available hardness meter (manufactured by Kobunshi Keiki Co., Ltd., model JA). As is clear from Figure 4, if there is no difference in hardness between the pressure roll and the heat fixing roll, no wrinkles will occur on the envelope; on the other hand, if there is a large difference in hardness between the two rolls, In most cases, wrinkles occur and the envelope becomes deformed. In other words, the above hardness difference is within 15° (within the range of parallel chain lines), preferably within 10° (within the range of parallel solid lines)
If so, the concave surface of the pressure contact portion 3 as shown in FIG. 3 can be avoided. In this case, if the hardness of the pressure roll and/or heat fixing roll exceeds 80", no paper wrinkles will occur, but the fixing performance will be insufficient due to the insufficient nip width.On the other hand, the nip width will be insufficient. When increasing the fusing pressure to ensure.

On the contrary, the result is that the paper wrinkles.

Next, FIG. 5 is a diagram showing how wrinkles occur on the toner image bearing member when the pressure roll and the heat fixing roll are combined with various outside diameters. It depends on the conditions. As is clear from FIG. 5, when there is no difference in outer diameter between the pressure roll and the heat fixing roll, no wrinkles are observed on the envelope as a toner image carrier. If the difference in outer diameter between the two rolls is large, wrinkles will occur and the envelope will be deformed. That is, if the difference in outer diameter is within 51 (within the range of parallel chain lines), preferably within 21) (within the range of parallel solid lines), it is possible to avoid wrinkles from forming on the envelope. In particular, if the outer diameters of both rolls are formed to be substantially the same, overall good results can be obtained.

FIG. 2 is a partially sectional side view showing another embodiment of the present invention, and the same parts are designated by the same reference numerals as in FIG. 1. In Fig. 2, 16 and 26 are heat-resistant mold release layers, which are made of a material with low surface energy such as fluorine resin.
It is formed to a thickness of 0 to 50 μm. With this configuration, especially in the case of high-speed fixing where the fixing speed is 1 Q Oam/sec or more, it is possible to improve fixing performance and offset resistance, and obtain good results in terms of preventing wrinkles. Can be done.

In addition, in order to prevent wrinkles from forming when making double-sided copies on thin paper, there is a means for forming both the pressure roll and the heat-fixing roll into the above-described roll structure.

It is disclosed in Japanese Unexamined Patent Publication No. 59-74548. However, in the case described in the above-mentioned publication, since the thickness of the heat-resistant elastic layer of the heat-fixing roll and the thickness of the heat-resistant elastic layer of the pressure roll are different, a substantially flat pressure contact portion is not formed, and the envelope In the case of such carriers, no wrinkle prevention effect can be expected. Also, JP-A-61-786
Although the above-mentioned roll structure is also described in Publication No. 4, the thicknesses of the elastic layers of both rolls are different in this case as well.

Similarly to the above, the effect of preventing wrinkles on carriers such as envelopes cannot be expected. Further, even if the positional relationship between the heat fixing roll and the pressure roll is reversed, the effect is the same.

In this embodiment, an example is described in which an envelope is used as the toner image carrier, but plain paper may also be used.

In this case, the pressure contact portion formed between the pressure roll and the heat fixing roll may be in a state as shown in FIG. This improves the appearance of wrinkles, thereby preventing the appearance of wrinkles.

〔Effect of the invention〕

Since the heat fixing roll of the present invention has the structure and function as described above, it has the effect of improving paper feeding performance, making wrinkles less likely to occur, and improving fixing performance. In addition, by using the pressure roll facing the heat-fixing roll, which has a small difference in surface hardness, the roll pressure contact area can be flattened. 9. For example, even if the toner image bearing member is composed of multiple layers such as an envelope, it is possible to fix a normal toner image with good image quality without wrinkles. Also especially.

Both the heat fixing roll and the pressure roll have a roll structure in which a heat-resistant elastic layer and a heat-resistant release layer or release layer reciprocal layer are formed on a core metal, so that it can be used like an envelope without wrinkles. The toner image on the carrier can be fixed well even under high speed conditions. In addition, in a normal fixing device, a cleaning blade is brought into sliding contact with the heat-fixing roll to remove attached toner, but even if foreign matter gets caught or enters between the heat-fixing roll and the cleaning blade, Since the heat fixing roll is imparted with elasticity, it is possible to prevent scratches from occurring on the surface.

Furthermore, since the material forming the heat-resistant elastic layer has insulating properties, the insulating properties are improved.

This has the effect of increasing safety.

[Brief explanation of the drawing]

1 and 2 are partially cross-sectional side views showing embodiments of the present invention, FIG. 3 is a partially cross-sectional side view showing a state in which a conventional heating fixing roll and a pressure roll are in pressure contact, and FIG. 5 is a diagram showing the occurrence of wrinkles on an envelope when the surface hardness of the pressure roll and heat fixing roll is changed in an example of the present invention, and FIG. 5 shows the outer diameters of the pressure roll and heat fixing roll It is a figure which shows the wrinkle occurrence state of the envelope in the case of changing. 1: Pressure roll, 2: Heat fixing roll, 3: Pressure contact part.

Claims (4)

[Claims] (1) A bonding layer, an insulating layer, and a heat generating layer are laminated in this order on the outer surface of a cylindrical core made of a metal or alloy with good thermal conductivity, and a heat-resistant elastic layer and a mold release layer are further layered on the outside. A heating fixing roll characterized by being integrally provided with. (2) Claim 1 in which the surface hardness is 80° or less
The heating fixing roll described in Section 1. (3) The heat fixing roll according to claim 1 or 2, wherein the heat-resistant elastic layer has a thickness of 1 to 2 mm. (4) The thermal conductivity of the material constituting the heat-resistant elastic layer is 0.2
The heat fixing roll according to any one of claims 1 to 3, which has a temperature of x10^-^3 cal/cm·sec·°C or more.