JP3180126B2 - Method for producing porous elastic body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a porous elastic body having micro continuous pores .

In general, a porous elastic material called a sponge has various uses such as cushioning, cushioning, water absorption, pressurization and the like, and its base material is polyurethane, polyamide, polyester, polyacrylate, butadiene / acrylonitrile copolymer. And many other polymeric materials are used.

[0003] Of these porous elastic materials, there are many applications where a water absorbing effect and a buffering effect are expected, for example, and many of those used in daily life do not matter much in the size and distribution of pores. However, industrially, there are uses in which the size and use of pores have important significance in terms of the accuracy and durability of products.

In recent years, copiers, laser beam printers, facsimile machines and the like utilizing the electrophotographic system have been widely spread. Porous elastic bodies are often used for rollers used for development, transfer, and the like in these electrophotographic systems.

In the electrophotographic system, a latent image such as a character or a figure is formed on a semiconductor layer on the surface of a photosensitive drum PS by irradiating a laser or an LED or the like, as shown in FIG. Then, after toner is applied by a developing drum DD to form a toner image, the toner image is transferred onto a recording sheet P and is heated and fixed while passing through a fixing device FD.

In such a process, the photosensitive drum PS
For uniform supply of toner to the surface, the developing drum DD
A roller made of porous urethane, which is a porous elastic body, is suitable. This is because the pores formed on the surface of the porous urethane are suitable for supplying the toner powder while partially supporting it.

On the other hand, the particle size of the toner in the electrophotographic system is closely related to the pixel density, and the conventional 200 dpi.
Therefore, when the resolution is increased to 400 dpi, and further to 600 dpi, the demand for the toner particle size becomes strict,
Those having a size of 10 μm or less are required.

When a conventional porous urethane roller having large pores is used for a toner having such a small particle diameter, the toner particles are completely immersed in the pores, and the toner particles are uniformly deposited on the photosensitive drum. That is, it is impossible to expect a sufficient toner supply. On the other hand, if the pore diameter is too small, it becomes the same as the smooth surface, and sufficient toner cannot be supplied.

A desirable property of the surface of this kind of porous elastic roller for supplying toner is that pores having a diameter slightly smaller than the average particle diameter of the toner are distributed as evenly as possible. Therefore, for example, when the toner particle diameter is about 10 μm, it is required that pores of about 6 to 8 μm are formed uniformly.

In addition, the porous elastic roller must have elasticity to maintain uniform contact with the solid photosensitive drum, have uniform conductivity, and have excellent long-term durability. Requirements.

[0011]

2. Description of the Related Art As a method for producing a porous elastic material as described above, there is widely used a method in which a porous product is mixed with a raw material of a polymer resin composition, extruded, and then the porous product is taken out by appropriate means. Has been adopted.

As the polymer resin composition to be used as the base material, polyurethane, polystyrene, polyethylene, polypropylene, acrylic resin, polyamide and the like are used. As the pore product, polyvinyl alcohol, polyethylene oxide, methyl cellulose, or a high molecular polysaccharide is used in combination with a foaming material as appropriate.

[0013] To these raw materials, further necessary components such as a UV resistance improving material, a stabilizer, an abrasive, a compatibilizer for blending a plurality of raw materials, a conductivity improving material, etc. are mixed according to the intended use. Knead the mixture. The high-viscosity kneaded raw material thus obtained is adjusted to a desired mold, and extrusion molding or press molding is performed.

After drying the basic molded article thus obtained, the pore product is eluted with a solvent or a solvent vapor for selectively eluting the pore product without affecting the base material composition. To obtain a porous elastic body.

[0015] Since porous urethanes based on polyurethane are often used as porous elastic bodies which have been widely used in the past, a method for producing porous urethane according to the prior art will be disclosed below.

In the process of producing a polyurethane by stirring a polyisocyanate and a polyether polyol or a polyester polyol, water or chlorofluorocarbon is added to form a porous urethane.

However, the porous urethane thus obtained is often used as a cushion material.
The number of pores is more than 50 μm. Therefore, the present invention is not suitable for the use of the developing roller for supplying the toner which is the target of the present invention.

As another method, a polyurethane resin is dissolved in an organic solvent such as dimethylformamide (DMF) or methyl ethyl ketone (MEK), and a substance that does not dissolve in the solvent, for example, an inorganic salt, polyvinyl alcohol (PVA), or glutamate is used. And the like.

Thereafter, the solvent is removed from the substance by evaporation, washing, water bath, etc., and the mixture is molded. Further, by dissolving an additive substance for forming pores, porous urethane can be obtained. The pores in this case are 20 to 50 μm, and are applied to, for example, cosmetic puffs.

The conventional porous urethane obtained by the production method as shown here has pores formed by utilizing foaming with water or the like or by the particle size of the additive substance. Therefore,
Large pore size and low reproducibility, for example, 10μ
m cannot be applied to a developing roller for supplying fine toner.

[0021]

SUMMARY OF THE INVENTION A method for producing a porous urethane which can make the pore size of a porous elastic material according to the prior art fine and uniform and can be evenly dispersed.
The task is to provide a law.

[0022]

FIG. 1 is a basic process diagram of a method for producing a porous elastic body according to the present invention. In a first process, a polyurethane elastomer is dissolved in a solvent.
A necessary auxiliary material such as a conductive material, a foaming material, and 1 to 40% by weight of hydroxyethyl cellulose are added and kneaded to obtain a high-viscosity substance.

Next, in a second step, the high-viscosity substance formed in the first step is molded into a basic molded body having a desired shape. Thereafter, in a third step, the solvent in the urethane is replaced with water to form continuous pores. The object having fine open cells formed in this manner is
In the process of drying, a necessary finishing operation is performed to obtain a product.

The required finishing operation varies depending on the final product. In the case of an electrophotographic roller, a cylindrical molded body is obtained by extrusion molding or press molding, dried to some extent, and then passed through a shaft. After bonding, drying and polishing operations are performed.

The polishing operation is performed for the purpose of adjusting the surface properties and increasing the smoothness and roundness in order to ensure uniform contact with the photosensitive drum.

The porous urethane obtained by the present invention is a transfer roller as an elastic body that presses the paper when the toner image formed on the photosensitive drum is transferred to the recording paper in the same electrophotographic equipment. Also suitable as.

As a solvent for dissolving the urethane elastomer, dimethylformamide (DMF), methyl ethyl ketone (MEK) and the like can be used. Carbon black is suitable as an additive for obtaining uniform conductivity. Further, as a foaming agent in this case, an inorganic salt, a water-soluble resin, or the like can be used.

Further, in the present invention, a surfactant can be added to form continuous pores in which a plurality of pores communicate with each other. Advantageously, the surfactant is hydrophilic.

[0029]

In such a construction, the urethane elastomer and the hydroxyethyl cellulose as an additive are dissolved in a solvent (D).
When dissolved in MF) and sufficiently kneaded, the added substances are evenly dispersed in the urethane elastomer.

From the resulting high-viscosity material, a basic molded body having a shape that allows for shrinkage due to drying, processing margins such as polishing, etc. is finally formed into a required shape.

Thereafter, the molded body is cured by removing the solvent. Further immersion in water elutes hydroxyethylcellulose, which is an additive substance, and the elution traces form micropores.

Very fine, substantially uniform pores of, for example, 8 μm or less are dispersed on the surface of the formed body thus formed. The pore diameter increases as the amount of the solvent increases, and decreases as the amount of the solvent decreases. Also, the number of pores can be adjusted here by the amount of hydroxyethylcellulose added.

[0033]

Embodiments of the present invention will be described below.

Example 1 Polycarbonate urethane (manufactured by Sanyo Chemical Co., Ltd.) 10 to 20% by weight Methyl ethyl ketone (MEK) (manufactured by Nitto Chemical Co., Ltd.) 30 to 50% by weight Surfactant (manufactured by Sanyo Chemical Co., Ltd.) 0.1 to 10% by weight Hydroxyethyl cellulose (manufactured by Daicel Corporation) 20 to 40% by weight

In this example, the above materials were used, and a urethane resin and hydroxyethyl cellulose were dissolved in methyl ethyl ketone (MEK) as a solvent. Here, a surfactant was also added at the same time (first step in FIG. 1).

Next, here, after forming a cylindrical basic molded body by press molding, methyl ethyl ketone was evaporated to cure the molded article (second step in FIG. 1).

Next, the molded article thus obtained was immersed in water in a water tank to dissolve and remove the hydroxyethyl cellulose (the second step in FIG. 1), and then dried (the second step in FIG. 1). Step 2). As a result, the surface of the obtained molded article was confirmed with an optical microscope, and it was confirmed that pores of 10 μm or less were formed.

Example 2 Example 2 was repeated, except that dimethylformamide (DMF) was used in an amount of 30 to 50% by weight in place of methyl ethyl ketone (MEK).

Since dimethylformamide (DMF) used in this example did not evaporate, the solvent was eluted in a water bath. Also in this example, the surface of the molded article was confirmed after drying, but fine pores were obtained.

Example 3 A shaft was bonded to the center hole of the cylindrical molded product obtained in Examples 1 and 2 to form a roller. Finishing was performed in the same manner as for a conventional porous urethane roller. Therefore, it was confirmed that there was no particular increase in costs in the manufacturing and finishing processes.

[0041]

As described in detail above, according to the method for producing a porous urethane according to the present invention, a porous urethane having an average pore diameter of 8 μm or less was obtained by a process almost the same as the conventional process.

As a result, by forming the developing rollers of various devices of the electrophotographic system with the porous urethane obtained in this manner, the toner supply efficiency is improved, and fine toner particles can be used. It is possible to cope with image formation with improved density.

The diameter and density of the pores can be adjusted by the amount of the additive hydroxyethyl cellulose and the amount of the solvent. Therefore, it is possible to sufficiently cope with the need to reduce the pore size when a finer toner is used in the future.

[Brief description of the drawings]

FIG. 1 is a process explanatory view of a method for producing a porous urethane according to the present invention.

FIG. 2 is an explanatory diagram illustrating a structure of a main part of an electrophotographic image forming unit.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI B29K 105: 04 (72) Inventor Chiaki Sekioka 1405 Daimaru, Daiji, Inagi-shi, Tokyo Inside Fujitsu Isotec Co., Ltd. (72) Inventor Hidefumi Tazaki 1405, Daimaru, Inagi-shi, Tokyo Fujitsu Isotec Co., Ltd. (56) References JP-A-1-185572 (JP, A) JP-A-2-296267 (JP, A) JP-A 64-31183 (JP, A) JP-A-2-84576 (JP, A) JP-A-56-135529 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 9/00-9/42 B29D 31 / 00 C08L 101/00 G03G 15/08 G03G 15/16

Claims (5)

(57) [Claims] 1. A step of dissolving a polymer substance and a water-soluble and solvent-soluble vegetable fiber additive with a solvent, a step of adding a hydrophilic surfactant, and a basic molding from the obtained high-viscosity object. Forming a product, evaporating a solvent from the basic molded product, curing the same, and then immersing the basic molded product in water to elute the vegetable fiber additive. . 2. The method for producing a porous elastic body according to claim 1, wherein the polymer substance is a urethane elastomer, and the vegetable fiber additive is hydroxyethyl cellulose. 3. The method for producing a porous elastic body according to claim 1, wherein the hydrophilic surfactant is a sulfosuccinate surfactant. 4. The method for producing a porous elastic body according to claim 1, wherein the solvent is dimethylformamide. 5. The method according to claim 1, wherein the solvent is methyl ethyl ketone.