JPH1124476A - Manufacture of tube coated roller and the same roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacture of a tube coated roller on the surface of which waviness does not occur even though thin rubber having low hardness is used and the roller manufactured by the same manufacture. SOLUTION: As to this manufacture of the tube coated roller; a resin tube 2 and a core body 3 passing through the tube 2 are attached inside the cavity of a forming mold, an elastic material precursor is injected between the resin tube and the core body, so that the cavity of the forming mold is filled with the resin tube, the elastic material precursor and the core body, and the elastic material precursor is hardened to be an elastic material. The elastic material is injected and hardened in a state where the resin tube is elongated when tensile force is given in a radial direction and/or in a length direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a tube-covered roller, and more particularly, to a heat fixing roller, a pressure roller, a laminating roller, a thermal platen roller and the like in an electrophotographic copying machine, a laser beam printer and the like. The present invention relates to a method for manufacturing a tube-coated roller having a long life and a tube-coated roller manufactured by the method.

[0002]

2. Description of the Related Art For example, in an electrophotographic process represented by an electrophotographic copying machine or a laser beam printer,
The toner image on the copy paper is fixed by a heat roller fixing method. In the heat roller fixing method, a nip is formed by a fixing roller and a pressure roller, and an image formed of toner is passed between the nips to apply heat and pressure to melt and fix the toner.

[0003] Since such a laser beam printer or the like needs to be continuously operated in an office for a long period of time, the fixing roller and the pressure roller as parts used here have a long life and do not need to be replaced for a long period of time. Is desired.
For this reason, a roller in which a sleeve made of a fluororesin is coated on the outside of silicone rubber is conventionally known as these rollers.

On the other hand, a compact fixing device is required in order to reduce the size of a printer. For this purpose, it is desirable to use a soft rubber, that is, a rubber having a low hardness, for the roller in order to secure a sufficient nip width with a roller having a relatively small diameter. In order to improve the thermal response, it is preferable to reduce the thickness of the rubber.

[0005] However, if the rubber of the above-described tube-covered roller intended to extend the life of the roller is made lower in hardness and thinner, there arises a problem that the roller surface has irregularities, that is, "undulations" during its production. Conventional 5
It is considered that such a problem did not occur in a roller formed of a hard rubber having a rubber thickness of about 6 mm and a hardness of 25 or more because the residual stress was easily reduced. Since such undulations appear on the toner image,
It is not preferable for both the fixing side and the pressure side rollers.

[0006] Such undulation on the roller surface is not observed at the stage of primary vulcanization of the rubber, but occurs at the stage of secondary vulcanization. However, a roller having undergone only primary vulcanization without undulation is used in a printer. When mounted on a fixing device such as a roller, swell occurs on the roller surface during heat-up, that is, during operation, and further, the rubber is significantly deteriorated, the hardness of the roller is also reduced, the nip width is changed, and the roller transport speed is slightly changed. It also turned out to change.

[0007]

SUMMARY OF THE INVENTION Accordingly, in order to solve the above-mentioned problems, the present invention provides a method of manufacturing a tube-coated roller which does not cause undulation on the roller surface even if the rubber is thin and has low hardness. It is an object to provide a roller manufactured by the method.

[0008]

As a result of the research conducted by the present inventors, in the production of the above tube-covered roller,
It has been found that the generation of undulations can be suppressed by injecting and hardening the elastic material in a state where the resin-coated tube is stretched by applying tension in the radial direction and / or the length direction thereof.

Therefore, according to the present invention, a resin tube and a core passing therethrough are mounted in a mold cavity, and an elastic material precursor is injected between the resin tube and the core to form an elastic material precursor in the mold cavity. Is filled with a resin tube, an elastic material precursor, and a core, and the elastic material precursor is cured to form an elastic material, wherein the resin tube has a radial direction and / or a length. It is another object of the present invention to provide the manufacturing method, wherein the elastic material is injected and hardened in a state where the elastic material is stretched by applying tension in a direction.

In a preferred embodiment of the method of the present invention, the hardness of the elastic material after curing is 20 or less according to JIS-A.

In a preferred embodiment of the method of the present invention, the resin tube is a fluororesin tube containing a fluororesin as a main component, and the elongation in the radial direction of the fluororesin tube is 5 to 20%, more preferably 10 to 20%. 20%.

In a preferred embodiment of the method of the present invention, the elongation percentage in the length direction of the fluororesin tube is 0.5 to 0.5.
10%, more preferably 1.5 to 10%.

In a preferred embodiment of the method of the present invention, a silicone rubber, particularly preferably an addition-reaction silicone rubber, is used as the elastic material. The minimum temperature of the secondary vulcanization in the thermal curing of silicone rubber is preferably 170 ° C.
Above.

In a preferred embodiment of the method of the present invention, the inner surface of the fluororesin tube is etched. More preferably, a primer is applied to the etched surface of the fluororesin tube.

According to the method of the present invention, even if the thickness of the elastic layer is 3 mm or less and the hardness after hardening is 20 or less according to JIS-A, the roller surface does not undulate as described above. A tube covering roller having an elastic material layer and a coating resin layer outside the elastic material layer on the outer periphery is obtained. When a resin containing a fluororesin as a main component is used for the coating resin layer, a roller having particularly excellent durability such as abrasion resistance can be obtained.

Therefore, the present invention further provides a tube-coated roller having an elastic material layer on the outer periphery of a core body and a coating resin layer on the outer side thereof, wherein the elastic layer has a thickness of 3 mm or less and a hardness of J
The present invention provides a tube coating roller having an IS-A of 20 or less, wherein the coating resin layer is made of a resin containing a fluorine resin as a main component.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

The tube-coated roller manufactured according to the present invention has a layer of an elastic material on the outer periphery of the core and a resin coating layer on the outer side thereof. The structure of such a roller itself is known, and its dimensions and other characteristics may be the same as those of a conventional roller.

The material of the core used for manufacturing the roller of the present invention is not particularly limited, and the same material as that used for the conventional roller can be used. For example,
It is preferable to use a pipe-shaped core made of metal such as iron, stainless steel, or aluminum, that is, a metal core. Such a core may have a diameter of, for example, 20 to 60 mm.

It is preferable to apply a black paint on the surface of the core to enhance light absorption. The surface of the cored bar is preferably degreased and washed to improve the adhesiveness. It is also preferable to perform blast treatment by chemical blast, sand blast, or the like.

A primer can be applied to the surface of the core as an adhesive. As the primer, a known primer conventionally used for such a purpose can be used.

The elastic material used for the layer made of the elastic material provided on the core body may be the same material as the conventional resin tube-coated roller, but in the present invention, a particularly high-grade elastic material is used. It is intended, and particularly has a hardness of 20 or less according to JIS-A. Also, as described below, the elastic material must be capable of being injected as a precursor into the mold.

As the elastic material as described above, for example, silicone rubber can be used, and a silicone rubber formed using diorganopolysiloxane such as diphenylpolysiloxane or dimethylpolysiloxane as a precursor can be used. Those formed using the addition reaction type silicone rubber as a precursor can be suitably used.

The addition type silicone rubber (addition type methylphenylpolysiloxane silicone rubber) as described above is
A polysiloxane obtained from a siloxane compound having an addition-type reactive group such as a vinyl group in addition to a methyl group and a phenyl group, which is crosslinked by an addition-cleavage reaction between the addition-type reactive group and a silane crosslinking agent. is there.

The above silicone rubber, for example,
It is produced from the polysiloxane represented by (I).

[0026]

Embedded image In the above formula (I), R ¹ , R ² , R ³ and R ⁴ independently represent a methyl group, a phenyl group or the like. In the case of the addition type silicone rubber, a part thereof is an addition type reactive group such as a vinyl group. n is from about 300 to about 2000.

When a phenyl group is used in 2 mol% or more of R ^{1 to} R ⁴ , a silicone rubber having swelling resistance to a release agent such as silicone oil can be obtained.

The addition type when the silicone rubber, the amount of addition type reactive group is preferably of the entire R ¹ ~R ⁴ 0.05~0.
It is about 35 mol%, more preferably about 0.1 to 0.3 mol%.

An addition-type reactive group such as a vinyl group is a functional group necessary for cross-linking. If the amount is less than 0.05% by mole, the polysiloxane is in a semi-cured state, making it difficult to obtain elasticity. On the other hand, if it exceeds 0.35 mol%, crosslinking proceeds too much, and the polysiloxane becomes hard and brittle, so that favorable elasticity cannot be obtained.

The degree of polymerization of the above polysiloxane is 25.
It is preferable that the viscosity is 30 to 400 poise expressed in terms of viscosity at ° C.
It is desirable to have a viscosity of preferably 1200 poise, more preferably 800 poise or less. The polymerization degree (n) of the polysiloxane is defined so as to obtain the above-mentioned viscosity. When n is less than about 300, the viscosity is too low, and it is difficult to manufacture the roller surface layer. And even if it can be produced, sufficient physical properties cannot be obtained. On the other hand, if n exceeds about 2,000, the viscosity becomes too high, which also makes it difficult to manufacture the roller surface layer.

Such a polyorganosiloxane is also a compound known per se, and can be produced by a known method.

The physical properties of the silicone rubber used for the layer made of the elastic material may be either insulating or semiconductive, and it is preferable that the thermal conductivity is high for a heat fixing roller.

In the tube covering roller of the present invention,
The elastic material layer preferably has a hardness according to JIS-A of 20 or less. If the hardness exceeds 20, the hardness of the roller is increased due to the fluororesin layer on the surface layer, and the load between the rollers must be increased in order to obtain a sufficient nip width. is there.

The elastic material is preferably a low creep rubber. Specifically, for example, a material having a compression set of 12% or less when compressed at 180 ° C. for 22 hours at 25%. . By using such a rubber having a low compression set, distortion can be prevented even when pressure is constantly applied between the rollers.

In the present invention, the thickness of the layer made of such an elastic material is preferably 3 mm or less because it is necessary not to lower the thermal response. If the thickness is 3 mm or more, the thermal responsiveness is deteriorated, and the fluctuation of the temperature width at the time of fixing the toner is so large that sufficient fixing property may not be secured in some cases.

As the resin of the outermost coating resin layer, a resin having excellent heat resistance is preferable because it is necessary to enable continuous use of the fixing roll at a high temperature of about 200 ° C., and tetrafluoroethylene / perfluoroalkoxy is preferred. Fluororesins such as ethylene copolymer (PFA) and tetrafluoroethylene / hexafluoropropylene copolymer (FEP) are preferred. These resins are excellent in toner releasability as compared with ethylene tetrafluoroethylene copolymer (ETFE) and are suitable as surface layer resins. In addition, PFA is more preferable from the viewpoint of heat resistance and bending crack resistance.

In the tube coating roller of the present invention, the PF
When using tube A, melt index (A
It is preferable to use a PFA having a PFA of 5 (g / 10 min) or less, particularly 2 (g / 10 min) or less (measured by STM D-2116). Further, such a fluororesin tube has a bending resistance of 1,000,000 times or more, for example, 1,000,000 to 2,000,000 times (ASTM D-2176-69 under a load of 1.25 kg using a sample of 13 mm × 90 mm × 0.2 mm).
(Measured number of repetitions of bending until a bending crack is generated in accordance with the above formula). By using a tube made of a fluororesin having such characteristics, a tube-coated roller excellent in durability such as abrasion resistance can be obtained.

The fluororesin tube used in the tube-coated roller of the present invention as described above is obtained as a tube formed by extrusion or the like. The fluororesin tube formed by such extrusion molding is different from that formed by applying a fluororesin dispersion on an elastic material layer, drying and firing, etc. There are no defects and durability such as high wear resistance can be obtained.

Such a fluororesin may contain a conductive filler to impart conductivity to prevent offset due to charging.

The kind of the conductive filler used for such a purpose is not particularly limited, and examples thereof include carbon black such as Ketjen black and metal powder such as aluminum. The average particle size of the conductive filler is preferably 0.5 μm or less in order to obtain stable and uniform conductivity.

The content of the conductive filler is usually about 0.1 to 5% by weight based on the resin. However, if the conductivity of the fluororesin layer is too high, when the toner on the recording paper comes into contact with the fluororesin layer of the fixing roll, the charge of the toner flows into the fluororesin layer, and an attractive force is generated between the recording paper and the toner. May be lost. To prevent such a phenomenon,
The outer layer preferably has a surface resistivity of 1 × 10 ¹² to 1 × 10 ¹⁶ Ω / □.

The thickness of the fluororesin layer is preferably in the range of 5 to 75 μm, more preferably 10 to 50 μm. If the thickness is 5 μm or less, it is difficult to extrude the tube as a fluororesin tube, and the roller is too thin to be stretched with a small force because it is too thin. On the other hand, when the thickness is 75 μm or more, the hardness of the roller becomes too hard, and the thermal conductivity of the fluororesin is low, so that the thermal responsiveness is not preferable.

Next, the method for producing the tube-coated roller of the present invention will be specifically described.

First, as shown in a schematic sectional view in FIG. 1, a fluororesin tube having an outer diameter smaller than the inner diameter of the mold 1 is placed in the cavity of the cylindrical mold 1 having the outer diameter of the roller to be formed. 2 and both ends are folded back to the outside of the mold 1,
Further, the core 3 is disposed concentrically with the mold 1 therein, and the mold cover 4 is fitted into both ends of the mold 1 to fix the fluororesin tube 2 and the core 3.

Thereafter, an elastic material precursor is injected between the resin tube 2 and the core 3 from the resin injection port 5 of the mold lid 4,
The space that can exist between the resin tube 2 and the core body 3 in the mold is filled. An air outlet 6 is provided in the opposite mold lid 4.

Then, the whole is usually heated to crosslink and cure the elastic material precursor (primary vulcanization), and after being appropriately cured, the integrated core, elastic material layer and coating resin layer are molded into a mold. And further heated and crosslinked (secondary vulcanization) to obtain a resin tube-coated roller.

In the method of manufacturing the resin tube-covered roller of the present invention, when the resin tube 2 and the core body 3 are fixed in the mold and the elastic material precursor is injected as described above, the tension is applied to the resin tube 2. So as to extend in the radial direction and / or the length direction.

The radial elongation is mainly obtained when the resin tube is mounted on the mold due to the difference between the outer diameter of the resin tube used and the inner diameter of the mold. It may be obtained by pressure. Therefore, when the resin tube is mounted on the mold, the resin tube does not have to be in close contact with the mold except at the fixed end, and the resin tube is stretched by injecting the elastic material precursor, and the metal tube is expanded. It can be in close contact with the inner surface of the mold. In that case, a hole for releasing air existing between the resin tube and the mold can be provided in the mold.

The extension of the resin tube in the length direction is as follows:
It is obtained by fixing the resin tube in a stretched state by applying tension when mounting the resin tube on the mold.

The degree of elongation of the resin tube is preferably at least 5% with respect to the original diameter of the tube to be used in order to obtain the effects of the present invention, and more preferably at least 10%. Since this elongation must be within the range of elastic deformation and does not cause permanent plastic deformation, the upper limit thereof is preferably about 20%.

Similarly, the elongation in the longitudinal direction of the tube is preferably at least 0.5%, more preferably at least 1.5%, based on the original length of the tube. The upper limit is about 10% for the same reason as described above.

The elongation of the resin tube may be applied independently in either the radial direction or the length direction, and tension may be applied simultaneously in both directions, but it is more preferable to apply tension in both directions. By applying the tension in this manner, it is considered that the residual stress of the roller at the time of the primary vulcanization is relieved, whereby a desired tube-coated roller can be obtained without causing undulation on the roller surface.

It is preferable that the inner surface of the resin tube be etched in order to improve the adhesiveness with the silicone rubber. The etching can be performed by a conventionally known method, for example, a chemical method such as a sodium-naphthalene method or a liquid ammonium method, or a physical method such as an excimer laser etching method or a low-temperature plasma method. In particular, when the tube thickness is 30 μm or less, chemical etching is difficult, so physical etching is suitable.

A primer may be applied to the etched surface in order to improve the adhesion between the silicone rubber and the fluororesin tube. The primer is preferably applied in a state where the resin tube is stretched. As the primer, a commercially available primer for a fluororesin can be suitably used. Examples of such commercially available primers include DY39-067 manufactured by Dow Corning Toray Co., Ltd. Such a primer may contain a conductive filler. The primer is usually applied uniformly on the inner surface of the fluororesin tube to a thickness of about 0.1 to 20 μm, preferably about 1 to 10 μm. An elastic material precursor is injected and injected between the fluororesin tube 2 and the core 1 fixed as described above, and such an elastic material precursor is usually a rubber containing a crosslinking agent and other additives. Inject as a compound. The crosslinking agent may be a conventionally known one. In the case of an addition type silicone rubber, a silane crosslinking agent is used.

As the optional component, those conventionally used for silicone rubber and the like can be used. For example, a filler can be added for the purpose of reinforcing and increasing the amount of silicone rubber. Examples of such a filler include silica, diatomaceous earth, quartz powder, clay, calcium carbonate, titanium oxide and the like. Particularly, the silica filler is preferably used for improving the strength of the silicone rubber, and may be either dry silica called fumed silica or wet silica called precipitated silica, and the hydroxyl group bonded to silicon atoms on the surface thereof is trimethylsilyl. And those whose surfaces have been subjected to a hydrophobic treatment with dimethylpolysiloxane having a low degree of polymerization, and those further containing an oxide of another metal such as titanium or aluminum as an auxiliary component. Such silica-based fillers,
Generally, it is used in an amount of 10 to 60 parts by weight, preferably 20 to 50 parts by weight, based on 100 parts by weight of the polyorganosiloxane.

An organosilane compound or a low molecular weight organopolysiloxane compound can be added to improve the dispersibility of the above-mentioned silica-based filler.
For example, a diorganopolysiloxane having a low degree of polymerization and having a silanol terminal blocked, diphenylsilanediol, dimethyldiethoxysilane and the like can be mentioned. The addition amount of such a compound is generally 0 to 30 parts by weight, preferably 1 to 30 parts by weight, particularly preferably 2 to 10 parts by weight based on 100 parts by weight of the polyorganosiloxane. An appropriate addition amount can be selected according to the type and blending amount of the system filler.

The elastic material precursor injected and injected into the mold as described above is usually cured by heating and vulcanization (primary vulcanization), and then removed from the mold and further heated (secondary vulcanization). Vulcanization) to obtain a tube-coated roller. In the case of silicone rubber, the primary vulcanization is preferably performed at a temperature of 100 to 170 ° C., and the secondary vulcanization is preferably performed at a temperature of 170 ° C. or higher, and usually at a temperature of about 200 ° C. By performing the secondary vulcanization at such a temperature, the heat resistance of the roller is significantly improved, and a roller having no undulation on the roller surface can be obtained.

The tube-covered roller thus obtained can be suitably used as a fixing roller, a pressure roller, etc. which come into contact with toner in a laser beam printer or the like.

[0059]

The present invention will be further described with reference to the following examples.

Roll forming length 360 mm, inner diameter 40
mm inside the mold cavity, outer diameter 35mm, thickness 50μm,
420 mm length fluororesin tube (350-J, manufactured by Mitsui / Dupont Fluorochemical, melt index 2
Of PFA) and then primer No. 18
B (manufactured by Shin-Etsu Chemical Co., Ltd.) is applied to the inner surface of the fluororesin tube, and an aluminum core (aluminum A505) having a length of 320 mm, a diameter of 34.8 mm, and a shaft thickness of 3 mm is coated therein.
6) was inserted, and lids were fitted to both ends of the mold, whereby the resin tube was fixed to the engaging portion between the mold and the lid, and the core metal was concentrically fixed to the mold. At this time, the fluororesin tube was fixed in a state of being stretched by 8.4 mm in the entire length direction (elongation: 2%).

Thereafter, a rubber compound having a viscosity of 800 poise and a specific gravity of 1.28 of the addition type methylphenylsilicone rubber precursor was injected from the resin injection port of the mold lid.

By injecting the rubber compound, the fluororesin is entirely extended in the radial direction, and the outer diameter is 40 mm.
Therefore, the radial elongation is about 14%.

The mold was heated and cured at 110 ° C. for 1 hour in a thermostatic oven, and the integrated roller was taken out of the mold and heated at 200 ° C. for 4 hours for secondary vulcanization. A coated roller was obtained.

The thickness of the elastic material layer of the obtained tube-coated roller was about 2.5 mm, and the hardness was 8 according to JIS-A.

A tube-coated roller having an elastic material layer thickness of about 1.5 mm was manufactured in the same manner as described above, using the same mold having an inner diameter of 38 mm as described above. In this case, the radial elongation of the fluororesin tube is about 8.6%. The hardness was 8 according to JIS-A as above.

In each of the obtained rollers, the surface of the roller was smooth and no waviness was generated. In addition, this roller is used for a full-color printer, and has a surface fixing temperature of 180 °.
When a paper-passing durability test was performed at ℃, it could be used without any trouble even after passing 150,000 sheets. Further, when the roller was started after being left for 5 days while being heated up, no abnormal noise was generated and the image quality was good.

Particularly, a fluororesin tube having a radial elongation of about 14% exhibits a particularly smooth surface and can be suitably used as a fixing roller.

[0068]

As described above, according to the method of manufacturing a tube-covered roller of the present invention in which an elastic material such as rubber is injected and hardened in a state where tension is applied to a fluororesin tube, a low-hardness and thick wall is obtained. Even if a thin rubber is used, a smooth roller having no undulation on the roller surface can be obtained.
The tube-coated roller obtained by such a method can use a rubber having a low hardness, so that the roller can be a soft roller, and thus a wide nip width can be obtained with a low load. Further, since the rubber thickness can be reduced, a roller having good thermal response can be obtained.

Also, since the tube is covered,
Even if silicone oil is applied, the roller diameter does not change, and even if the roller surface is shaved by paper, the offset property does not change because the surface layer material is a fluorocarbon resin having low adhesiveness. Therefore, the life of the roller is as long as 150,000 or more, and the roller is not required to be replaced, so that it is most suitable for an electrophotographic copying machine, a laser beam printer, and the like. By adopting such a roller as a fixing roller or a pressure roller, stable paper transportability can be obtained, and curling does not occur.

Further, since the surface layer is made of a fluororesin, the amount of oil applied to the roller surface can be reduced or not used, and oilless fixing can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a method for manufacturing a tube-coated roller of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Mold (molding mold) 2 ... Fluororesin tube 3 ... Core 4 ... Mold cover 5 ... Resin injection port 6 Air outlet

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Daisuke Sakai 2-1-1 Oda Sakae, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside Showa Electric Wire & Cable Co., Ltd. No. 1-1, Showa Electric Wire & Cable Co., Ltd.

Claims (9)

[Claims] 1. A resin tube and a core passing therethrough are mounted in a mold cavity, and an elastic material precursor is injected between the resin tube and the core to form a resin tube in the mold cavity. Filling the elastic tube with an elastic material precursor and a core, and curing the elastic material precursor to form an elastic material, wherein the resin tube is tensioned in its radial direction and / or length direction. The method according to claim 1, wherein the elastic material is injected and cured in a stretched state. 2. The method according to claim 1, wherein the hardness of the cured elastic material is 20 or less according to JIS-A. 3. The resin tube according to claim 1, wherein the resin tube is a fluorine resin tube containing a fluorine resin as a main component, and a radial elongation of the fluorine resin tube is 5 to 20%. Production method. 4. The production method according to claim 3, wherein the elongation of the fluororesin tube in the length direction is 0.5 to 10%. 5. The method according to claim 1, wherein said elastic material is silicone rubber. 6. The method according to claim 5, wherein the minimum temperature of the secondary vulcanization in thermal curing of the silicone rubber is 170 ° C. or higher. 7. The method according to claim 1, wherein an inner surface of the fluororesin tube is etched. 8. The method according to claim 7, wherein a primer is applied to the etched surface. 9. A tube-coated roller having an elastic material layer on the outer periphery of a core body and a coating resin layer outside the core material, wherein the thickness of the elastic layer is 3 mm or less, the hardness is 20 or less according to JIS-A, and the coating resin is A tube-coated roller, wherein the layer is made of a resin containing a fluororesin as a main component.