JPH09131810A - Manufacture of smooth surface roller and smooth surface roller manufactured by method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a resin or rubber roller having excellent surface smoothness which can be used as a roller for an electrophotographic apparatus without necessity of post-processing such as polishing or coating. SOLUTION: A metal mold material having the same outer diameter as that of a desired roller is disposed in the state that the shaft core provided at the end face of the material is fixed to the inner wall of the molding space of a mold in the space of the mold. Ambient temperature-curable silicone rubber material or fluorine resin material is poured in the space, solidified or reacted to be cured, and then released from the mold, thereby manufacturing a resin mold 3. Thereafter, the mold is again contained in the mold. The end of a metal shaft 4 inserted into the radial center of the resin mold is fixed to the inner wall of the space. Then, roller molding resin or rubber material is poured in the mold 3, solidified or thermally cured, and then released from the mold. Further, the formed roller is removed from the mold 3 to obtain a smooth surface roller.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a roller made of resin or rubber having a smooth surface, particularly polyurethane foam, and a surface smooth roller manufactured by the method. The surface smoothing roller of the present invention is a charging roller,
It is used as a roller for an electrophotographic apparatus such as a transfer roller and a developing roller.

[0002]

2. Description of the Related Art Rollers having a smooth surface are manufactured by the following two methods, which are roughly classified from the conventional methods. One method is to form a coating layer made of an appropriate material on the surface of a roller that is finished to a substantially product size, and this method can be applied to both foaming rollers and non-foaming rollers. Another method is to form a roller that is slightly larger than the product size by press molding, extrusion molding, etc., and then polish the surface to the required size, which is mainly made of rubber and is a non-foaming roller. Applied to the manufacture of.

In various rollers such as a charging roller and a developing roller used in an electrophotographic copying machine or printer,
It is one of the important characteristics that the surface is smooth, and in addition, in the charging roller and the like, low hardness is desired to secure the nip width with the photosensitive drum and to prevent squeaking noise. There is. When the roller is made of non-foamed material,
To reduce the hardness, it is necessary to add a plasticizer or the like, but the plasticizer may migrate to the photosensitive drum and cause damage.

When the roller is made of foam, a method of providing a soft coating layer on the surface is adopted.
There is a problem that the coating agent may be sucked into the cell, or the shape of the cell may be projected on the roller surface as it is. If a coating agent is applied in multiple layers to prevent this, a new problem may occur in that the resistance value becomes difficult to control.

Further, as a method of obtaining a roller having a skin layer on the surface without polishing operation, for example, a method of using a metal pipe as a molding die and injecting a resin raw material into the inside thereof can be considered. However, in practice, it is difficult to apply a release agent or the like to the inner surface of the pipe to provide releasability, and even if it is possible to apply the release agent, the roller is not removed after the resin raw material is solidified and cured. It is very difficult to remove from the pipe, and this method is not practical.

[0006]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems, and to produce a resin mold having a specific mold releasability and to form a roller in the resin mold. Alternatively, a method for producing a roller having a smooth surface by injecting a rubber raw material, solidifying, reacting, and curing and then removing the roller from a resin mold, and a surface smooth roller produced by the method are provided. With the goal. The roller of the present invention can be directly put to practical use without requiring post-processing such as polishing and coating after molding, is easy to manufacture, and is very economical.

[0007]

According to a first aspect of the present invention, there is provided a method for manufacturing a surface smoothing roller, wherein a metal having a circular cross-sectional outer shape and a shaft center in a radial center portion of both end surfaces in a mold space of a mold. The mold material made of is placed in a state where the shaft core is fixed to the inner wall of the mold space, and then a resin raw material is injected into the space formed by the inner wall of the mold space and the outer surface of the mold material, After the resin raw material is solidified or reacted and cured, it is demolded, and the above mold material is removed from the solidified, reacted, and cured resin to produce a resin mold, and then the center portion in the radial direction is attached to the resin mold. Through, after inserting the shaft over its entire length, the resin mold is housed in the mold space, both ends of the shaft are fixed to the inner wall of the mold space, then in the resin mold, By injecting resin raw material or rubber raw material, solidifying or reacting and curing And the shaft, forms a roller made of a resin portion or the rubber portion covering the portion excluding the both end portions of the shaft, after demolding, from the resin mold in,
The roller is extracted.

The "mold space" of the "mold" has a shape and dimensions such that when the "metal mold material" is arranged, a space is formed between the inner wall of the mold and the outer surface of the mold material. Good.
Then, it is usually preferable that the length thereof is substantially the same as the length of the mold material and the diameter and shape thereof are larger than the outer diameter of the mold material by about 1 to 20 mm. Also, on the inner wall,
A recess having a shape and dimensions substantially the same as the outer shape of the shaft core is formed for fixing the "shaft core" provided in the radial center of both end surfaces of the mold material.

The mold space that forms the outer shape of the "resin mold" may have a square cross section or the like, but the cross section is circular as described above, and the centroid of the resin mold cross section is used. It is preferable to arrange so that the center line of the “shaft” of the roller obtained as a product and the “shaft” of the product coincide. This makes it possible to minimize the amount of expensive resin raw material for producing the resin mold, which is advantageous in terms of cost. It is also preferable in that when the resin or rubber raw material injected into the resin mold for forming the roller is solidified, reacted or cured, it is uniformly heated in the circumferential direction to form a uniform roller. Since the shaft requires considerable strength, a metal shaft is usually used.

When the center of the shaft of the roller obtained as a product is aligned with the centroid of the cross section of the resin mold as described above, the wall thickness of the resin mold is approximately half the above dimensional difference. If the difference between the inner diameter of the mold space and the outer diameter of the mold material is less than 1 mm, that is, if the wall thickness of the resin mold is less than 0.5 mm, the resin mold will lack strength and will expand and deform during demolding. There is. Further, even if it exceeds 20 mm, that is, if the wall thickness of the resin mold is thicker than 10 mm, it is meaningless only because the wall thickness becomes excessive, and an expensive material is wastefully used, which is not preferable. . It is also disadvantageous in terms of heat conduction to the resin raw material. The wall thickness of this resin mold is 1 to 10 m
If m, especially about 3 to 7 mm, it is preferable because it has sufficient strength and good heat conduction.

The surface smoothing roller of the second invention is characterized in that it is manufactured by the method of the first invention, and that the resin raw material for producing the resin mold is a room temperature vulcanizing type silicone resin raw material. The surface smoothing roller of the fourth invention is the first
The resin raw material produced by the method of the invention for producing the resin mold is a fluororesin raw material. Further, the surface smoothing roller of the sixth invention is manufactured by the method according to claim 1, and 1 to 100 parts by weight of an inorganic filler is mixed with 100 parts by weight of the resin raw material for producing the resin mold. It is characterized by

As the above "resin raw material" for forming the resin mold, "room temperature vulcanizing type silicone resin raw material" or "fluorine resin raw material" is suitable. As the room temperature vulcanizing type silicone resin raw material, a two-part type which generally has poor adhesiveness and produces a silicone resin exhibiting excellent releasability is used. The two-pack type includes a condensation type and an addition type depending on the curing reaction mechanism, but vinyl siloxane and Si-H
In the case of the addition type in which a siloxane having a bond is reacted with a platinum compound or the like as a catalyst, by-products are not generated at all, and thus it is more preferable in the present invention.

Further, in order to further enhance the releasability of the silicone resin, it is preferable to blend "silicone oil" into the room temperature vulcanizing type silicone resin raw material as in the third invention. This makes it easier to remove the roller from the resin mold. As the silicone oil, straight silicone oil such as dimethyl silicone oil and methylphenyl silicone oil can be used, and its viscosity is not particularly limited.

The blending amount of the above silicone oil is "1-5" based on 100 weight of room temperature vulcanizing type silicone resin raw material.
5 parts by weight ", especially 10 to 50 parts by weight, further 40 to 50 parts by weight
A range of parts by weight is preferred. If the amount is less than 1 part by weight, the releasability is not improved so much, and if it exceeds 55 parts by weight, the silicone oil may exude from the surface of the resin mold and stain the roller surface, Further, the strength of the silicone resin is impaired, which is not preferable.

Further, as the above "fluorine resin raw material",
If it can be melted by heating and poured into the mold,
It can be used without particular limitation. As such a fluororesin raw material, after solidification, vinylidene fluoride-
Common thermoplastic resins such as propylene hexafluoride copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, and tetrafluoroethylene-propylene copolymer are used. It can be illustrated.

If the resin mold has good thermal conductivity,
Since the resin or rubber raw material for forming the roller can be solidified or reacted and cured more efficiently to increase the curing property, the thermal conductivity of the resin constituting the resin mold such as silicone resin or fluororesin can be increased. preferable. This thermal conductivity can be improved by adding an appropriate amount of an inorganic filler such as alumina, silica, or calcium carbonate to the resin raw material for producing the resin mold. When the content of the inorganic filler is less than 1 part by weight, the thermal conductivity is hardly improved, and when it exceeds 100 parts by weight, the physical properties of the resin tend to deteriorate, which is not preferable. This compounding amount is especially 20
The amount is preferably 90 to 90 parts by weight, more preferably 40 to 80 parts by weight. Within this range, a usable resin mold having good thermal conductivity can be obtained.

The above-mentioned "resin raw material or rubber raw material" that constitutes the roller can flow at room temperature or by appropriate heating and can be injected into the resin mold, and then at room temperature or appropriately heated. It is possible to use a material that solidifies, reacts, or cures with time. Examples thereof include liquid butadiene rubber, liquid polyisoprene rubber and other epoxies, liquid rubber raw materials that are chain extended, crosslinked and cured by vinyl monomers and the like, and castable resin raw materials such as epoxy resins and urethane resins. .

Among the above various resin or rubber raw materials,
Polyurethane foam raw materials, which have been widely used as materials for charging rollers, developing rollers, transfer rollers and the like for electrophotographic apparatuses, are particularly preferable. Polyurethane foam stirs and mixes polyisocyanate and polyol components,
It is obtained by reacting and curing. As the polyisocyanate, various ones can be used,
Among them, MDI, TDI or a mixture thereof and M
Modified products of DI and TDI are preferable.

The type of the polyol contained in the polyol component is not particularly limited, but polypropylene glycol, polyolefin adipate, polycaprolactone, polytetramethylene ether glycol and the like are preferable. In particular, a polymer polyol, that is, a polyol obtained by graft-polymerizing an ethylenically unsaturated compound such as acrylonitrile, styrene, or methyl methacrylate to a polyether polyol is preferable, and they are used in the state of an insoluble and highly stable suspension. To be done.

If the roller is soft with a relatively low hardness, a soft foam with a low density is used. In this flexible foam, water is mainly used as a foaming agent, but dichloromethane or the like may be used together for the purpose of suppressing heat generation. As the catalyst, an amine-based catalyst, particularly a tertiary amine and a metal catalyst such as an organic tin compound such as stannas octoate, dibutyltin diacetate, and dibutyltin dilaurate are often used in combination.

As the foam stabilizer, a block copolymer of dimethylpolysiloxane and polyether is usually used, but in the case of high elasticity foam or the like, a special foam stabilizer obtained by adding an organic functional group to polysiloxane is used. Agents can also be used. Furthermore, in addition to these main components, the foam raw material
An appropriate amount of a colorant, a flame retardant, a filler and the like can be blended if necessary.

Further, in the application of a transfer roller in which a foam having a very high density is used, a polyurethane foam formed by chemical foaming using water, methylene chloride or the like as a foaming agent has too low hardness, and the dimensional accuracy as a roller is low. It cannot be ensured and the mechanical strength such as tensile strength and abrasion resistance is insufficient. For this reason, foams produced by mechanical foaming are usually used. Further, in order to make the foam have a high density of minute open cells, a foam stabilizer having a specific high molecular weight is used.

In the case of producing a foam by mechanical foaming, it is preferable to use substantially only a metal catalyst, and an excessive resinification reaction and a foaming reaction for producing carbon dioxide by a reaction between water and isocyanate are It is desirable not to have a sufficient amount of amine catalyst coexisting at a practical rate prior to the reaction cure step. As the metal catalyst, in addition to the above-mentioned stannas octoate, a catalyst suitable for polyurethane foam such as nickel acetyl acetate can be used, and the amount thereof is 0.001 to 100 parts by weight of the polyol.
About 0.3 parts by weight is preferable.

The roller of the present invention can be used as a transfer roller, a charging roller, a developing roller, a cleaning roller, a paper feeding roller, etc. of an electrophotographic apparatus such as an electrophotographic machine, an electrophotographic machine, various printers and the like. Since it is used in such a wide range of applications, the number of cells that is important for this type of roller is also wide, ranging from 20 to 500 cells / inch, but the preferred range varies depending on the individual roller.

In various rollers for electrophotographic apparatus, a plurality of rollers having different qualities may be used together in one process, and the suitable range of the number of cells also differs depending on the kind of toner used, so that the same number of cells is used. Even for rollers used, the range of the number of cells is not constant due to the wide variety of functions and specifications.
As described above, the number of cells cannot be uniquely determined, but to exemplify a preferable range of some of them, the transfer roller has 100 to 200 cells / inch, and the charging roller and the developing roller have 200 to 400 cells / inch. Rollers and the like.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for manufacturing a surface smoothing roller of the present invention will be described in detail with reference to Examples. (1) Production of resin mold FIG. 1 is a vertical cross-sectional view of a used mold. In FIG. 1, 1 is a mold main body, 11 is a resin material forming resin material and roller forming resin or rubber material material injection channel, 12 is a mold space, 13 is a metal mold material for resin mold manufacturing, and a shaft core of an end portion and The metal shaft end / fixed portion and 2 are metal mold materials for resin mold production.

With the mold shown in FIG. 1, four resin molds can be manufactured at the same time. However, the number of these molds depends on the number of rollers to be manufactured, the efficiency of resin mold manufacture, or the difficulty of uniform injection of resin raw material. It may be set as appropriate in consideration. Also, the mold space 12
Has a diameter of 22 mm, and the length may be appropriately determined depending on the type of printing paper such as A4 plate and B4 plate. The diameter of the metal mold material for producing the resin mold is 12 mm, and the length thereof is substantially the same as the size of the mold space.

Further, it is preferable that the shaft center of the end portion of the above-mentioned mold material and the end portion of the metal shaft of the roller have the same shape.
Since it is not necessary to attach an adapter or the like to the roller, it is possible to obtain a roller with higher dimensional accuracy and less deflection. The mold members are arranged concentrically in the radial center of the mold space, so that the wall thickness of the obtained resin mold is substantially uniform in the length direction and the circumferential direction, and is (22-12) / 2 = 5 mm. Become.

Then, a resin raw material for resin mold production having the following composition was injected into the space formed between the mold space and the mold material through the injection passage 11, and heated at 150 ° C. for 30 minutes to be cured. An attempt was made to pull out the metal mold material after demolding the cured product. As a result, a resin mold having an inner diameter equal to the outer diameter of the desired roller and a wall thickness of 5 mm was obtained, which could be easily removed.
The extremely smooth outer surface of the metal mold material is directly transferred to the inner surface of this resin mold, and there is no scratch when removing the mold material, and the inner surface of the resin mold is extremely smooth. Met.

Raw material for resin mold production (1) Room temperature vulcanization type silicone resin raw material "TSE345" manufactured by Toshiba Silicone Co., Ltd.
5T (A) "; 100 parts by weight, manufactured by Toshiba Silicone Co., Ltd., trade name" TSE3455 "
T (B) "; 10 parts by weight (2) Silicone oil 100 cS (manufactured by Toshiba Silicone Co., Ltd.); 50 parts by weight Incidentally, the blending amount of silicone oil is about 45 parts by weight based on 100 parts by weight of room temperature vulcanizing type silicone resin raw material. Becomes

(2) Manufacture of Roller Example 1 The resin mold manufactured as described above was housed again in the mold space of the mold, and at the same time, at the center in the radial direction thereof, a metal mold for the shaft of the product roller The shaft was inserted, and both ends thereof were fixed to fixing portions 13 provided at both ends of the inner wall of the mold space. Thereafter, the following raw materials for forming the roller and the following are mixed by stirring with a dynamic mixer while circulating nitrogen gas in a weight ratio such that the isocyanate index is 105, and through the injection passage 11, the inner surface of the resin mold and the metal shaft It was poured into the cylindrical space formed by the outer surface.

Roller forming raw material Polyol component a) Polymer polyol; (manufactured by Union Carbide,
(Product name "Niax LG56"), 100 parts by weight b) Nickel acetyl acetate 10-fold diluted product (metal catalyst); (OSi Specialties, product name "Lc5615"), 2 parts by weight c) Foam stabilizer; (Toray Silicone Co., Ltd.) Company name, product name "SF2961"), 10 parts by weight Polyisocyanate modified MDI; (manufactured by Nippon Polyurethane Co., product name "MTL")

After heating the mold at 150 ° C. for 30 minutes to react and cure the raw material for forming the roller, the resin mold was released from the mold, and then the roller was pulled out from the resin mold. I could easily pull it out. The surface roughness of the obtained roller is equal to the inner surface of the resin mold, that is, the outer surface of the metal mold material for resin mold production, and Rz (measurement method; JISB
0601) was 6 μm. Further, the roller had a low hardness (Asker C hardness meter: 40) and was a flexible roller. Further, the dimensional accuracy is high and the deflection is small, and the roller can be sufficiently used as a charging roller, a developing roller, etc. of a copying machine, a printer or the like.

FIG. 2 is a perspective view showing a cross section of the demolded resin mold and the formed roller as viewed obliquely. In FIG. 2, 3 is a resin type, 4 is a metal shaft,
Reference numeral 5 denotes a resin portion or a rubber portion (made of polyurethane foam in this embodiment) in which a roller forming resin or a rubber raw material is cured. In this embodiment, the roller composed of the metal shaft 4 and the polyurethane foam 5 could be easily extracted from the resin mold 3 without taking any special means. When not used in combination, it is necessary to perform an operation such as forcibly deforming the resin mold slightly.

Example 2 A resin mold was prepared in the same manner as in Example 1 except that the raw material for preparing the resin mold was the following heat conductive type silicone resin material. After reacting and curing under the same conditions as in Example 1 using the same raw material for forming the roller, the resin mold was released from the mold, and then the roller was tried to be pulled out from the resin mold. As a result, the resin mold had to be stretched and deformed to some extent, but could be easily extracted.

Raw material for resin mold production, trade name "TSE3431" manufactured by Toshiba Silicone Co., Ltd.
H (A) "; 100 parts by weight, manufactured by Toshiba Silicone Co., Ltd., trade name" TSE3431 "
H (B) "; 10 parts by weight The above silicone resin raw material contains 60 parts by weight of an aluminum oxide filler based on 100 parts by weight of the total amount.

For comparison, a roller having the same size was manufactured by a conventional manufacturing method. As a result, the surface roughness of the roller manufactured by the method of applying the surface coating after molding is R
The surface roughness of the roller manufactured by polishing with z of 6 μm and polishing after molding was 10 μm, which was the same as or substantially the same as the roller manufactured by the method of the present invention. However, while the roller of the present invention can be shipped as a product immediately after demolding and does not require post-processing, the polishing method requires considerable processing cost and time in the post-process, and the coating method does not. The processing cost is about double that of the polishing method.

[0038]

According to the roller manufacturing method of the first invention,
It is possible to obtain a surface smoothing roller which has a small surface roughness and is excellent in dimensional accuracy and which is suitable as various rollers for electrophotographic devices and the like without requiring post-processing such as polishing and coating. In addition, post-processing is unnecessary and man-hours can be reduced,
The cost is low, and the raw material for forming the roller may be the minimum necessary, which is also advantageous in this respect.

Further, in the surface smoothing rollers of the second and fourth inventions, by using a specific raw material for producing the resin mold, particularly as in the third invention, the silicone is used as the raw material for producing the resin mold. By blending silicone oil with the resin raw material, the releasability of the inner surface of the resin mold becomes higher, and the roller can be more easily removed from the resin mold.
Further, as in the fifth and sixth inventions, it is preferable to mix an inorganic filler in the raw material for producing the resin mold, because the heat conduction of the mold becomes good, and the reaction and effect of the raw material for forming the roller become easier. Furthermore, with the roller of the seventh aspect of the invention, a roller having no partition line and having excellent surface smoothness can be obtained without particularly requiring post-processing such as polishing.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a vertical cross section in a state where a mold material is arranged in a mold.

FIG. 2 is a perspective view showing a state in which a cross section of a resin mold and a roller that has been demolded is viewed obliquely.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1; Mold main body, 11; Injection path for resin raw material for resin mold production and resin or rubber raw material for forming roller, 12; Mold space, 1
3; metal mold material for resin mold manufacturing, end part axial core and metal shaft end part fixed part, 2; metal mold material for resin mold manufacturing, 3;
Resin type, 4; metal shaft, 5; resin portion or rubber portion obtained by solidifying, reacting, or curing a resin or rubber raw material for forming a roller.

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Claims (7)

[Claims] 1. A metal mold material having a circular cross-sectional outer shape and having a shaft center in the radial center of both end faces is fixed to the inner wall of the mold space in the mold space of the mold. The resin raw material is injected into the space formed by the inner wall of the mold space and the outer surface of the mold material, and the resin raw material is solidified or reacted and cured, and then demolded and solidified. Alternatively, the above mold material is removed from the reacted and hardened resin to prepare a resin mold, and then the resin mold is passed through the central portion in the radial direction and the shaft is inserted over the entire length thereof, A resin mold is housed in the mold space, both ends of the shaft are fixed to the inner wall of the mold space, and then a resin raw material or a rubber raw material is injected into the resin mold to solidify, react, or cure. Cover the shaft and the portion of the shaft excluding the both ends. After forming a roller consisting of a resin part or a rubber part to cover and removing from the mold, from the resin mold,
A method for manufacturing a surface smoothing roller, characterized in that the roller is pulled out. 2. A surface smoothing roller manufactured by the method according to claim 1, wherein the resin raw material for producing the resin mold is a room temperature vulcanizing type silicone resin raw material. 3. The room temperature vulcanizing type silicone resin raw material 10
The surface smoothing roller according to claim 2, wherein 1 to 55 parts by weight of silicone oil is mixed with 0 part by weight. 4. A surface smoothing roller manufactured by the method according to claim 1, wherein the resin raw material for producing the resin mold is a fluororesin raw material. 5. 1 to 100 parts by weight of the resin raw material
The surface smoothing roller according to any one of claims 2 to 4, which contains -100 parts by weight of an inorganic filler. 6. A surface smoothing roller produced by the method according to claim 1, wherein 1 to 100 parts by weight of an inorganic filler is mixed with 100 parts by weight of the resin raw material for producing the resin mold. 7. The surface smoothing roller according to claim 2, wherein the roller extracted from the resin mold does not have a partition line.