JPH06271703A - Production of porous elastic body and roller made of porous elastic body - Google Patents

Abstract

PURPOSE:To provide a process for producing a porous elastic body having interconnected micropores and to provide a roller made of such a porous body. CONSTITUTION:This production process comprises the steps of: dissolving a polymer substance and water-soluble and solvent-soluble vegetable fiber additive in a solvent, adding a hydrophilic surfactant to the solution, forming a basic molding from the obtained highly viscous product, evaporating the solvent from the molding to harden it and immersing the hardened molding in water to leach out the additive from it. A roller made of a porous elastic body having pores of an average pore diameter of 8mum or below in its surface is obtained.

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 continuous microscopic pores and a porous elastic body roller made of such a porous elastic body.

Generally, a porous elastic material called a sponge has various uses such as cushioning, cushioning, water absorption, pressurization, etc., and the basic material is polyurethane, polyamide, polyester, polyacrylate, butadiene / acrylonitrile copolymer. Many polymeric materials such as

Of these porous elastic bodies, there are many applications in which it is sufficient to expect a water absorption effect and a buffering effect, and many of them are used in daily life, and the size and distribution of pores do not matter so much. However, industrially, there are applications in which the size and application of pores have important meanings in terms of product accuracy and durability.

In recent years, electrophotographic copying machines, laser beam printers, facsimiles, and the like have become very popular. Porous elastic bodies are often used for rollers used for the purposes of development and transfer in these electrophotographic systems.

In the electrophotographic system, as shown in FIG. 2 showing the main part of the image forming section, a latent image such as characters and figures is formed on a semiconductor layer on the surface of the photosensitive drum PS by irradiation with a laser or an LED, and the latent image is formed. On the other hand, after the toner is applied by the developing drum DD to form a toner image, this toner image is transferred to the recording paper P and heated and fixed while passing through the fixing device FD.

The photosensitive drum PS in such a process
To uniformly supply the toner to the surface, the developing drum DD
As the roller, 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 method is closely related to the pixel density, and the particle size of the conventional 200 dpi.
Therefore, if it is improved to 400 dpi, and further to 600 dpi, the demand for the toner particle size becomes stricter,
Those having a thickness of 10 μm or less are required.

When the conventional porous urethane roller having large pores is used for the toner having such a small particle diameter, the toner particles are completely immersed in the pores, and the toner particles are evenly distributed on the photosensitive drum. It is impossible to expect a good toner supply. On the contrary, if the pore size is too small, the surface becomes the same as the smooth surface and the toner cannot be sufficiently supplied.

A desirable property of the surface of the porous elastic roller for supplying toner of this type 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 size is about 10 μm, it is required that the pores of about 6 to 8 μm are uniformly formed.

In addition, the porous elastic roller has elasticity to keep uniform contact with the solid photosensitive drum, has uniform conductivity, and has excellent durability for a long period of time. It is necessary to meet the requirements of.

[0011]

2. Description of the Related Art As a method for producing a porous elastic body 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 and the mixture is extruded and then the porous product is taken out by an appropriate means. Has been adopted.

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

In addition to these raw materials, necessary components such as a material for improving UV resistance, a stabilizer, an anti-wear agent, a compatibilizer for blending a plurality of raw materials, a conductivity improving material and the like are mixed depending on the use. Knead what was done. The high-viscosity kneading raw material thus obtained is put into a desired mold and subjected to extrusion molding or press molding.

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

Since many of the conventionally used porous elastic bodies are porous urethanes containing polyurethane as a base material, a method for producing a porous urethane according to the prior art will be disclosed below.

Porous urethane is formed by adding water or freon in the process of producing polyurethane by stirring polyisocyanate and polyether polyol or polyester polyol.

However, the porous urethane thus obtained is often used as a cushion material,
Most of the pores are 50 μm or more. Therefore, it is unsuitable for use as a developing roller for supplying toner, which is the object of the present invention.

As another method, a polyurethane resin is dissolved in dimethylformamide (DMF) or methylethylketone (MEK) which is an organic solvent, and a substance which is not dissolved in the solvent, such as an inorganic salt, polyvinyl alcohol (PVA) or glutamate. Etc. are added.

After that, the solvent is removed from this substance by evaporation, washing with water, a water bath or the like, and the substance is molded, and the additive substance for generating pores is dissolved to obtain a porous urethane. The pores in this case are 20 to 50 μm, and are applied to applications such as cosmetic puffs.

In the conventional porous urethane obtained by the manufacturing method as shown here, pores were formed by utilizing foaming with water or the like or by the particle size of the added substance. Therefore,
Large pore size and low reproducibility, eg 10μ
It cannot be applied to a developing roller for supplying fine toner such as m.

[0021]

[Problems to be Solved by the Invention] A method for producing a porous urethane capable of finely and uniformly dispersing and evenly dispersing the pore size in a conventional porous elastic body, and such a porous elastic body. It is an object to provide a roller by.

[0022]

FIG. 1 is a basic process diagram of a method for producing a porous elastic body according to the present invention. In the first process, a polyurethane elastomer is dissolved in a solvent,
Necessary auxiliary materials 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.

Then, in the second step, the high-viscosity substance formed in the first step is molded into a basic molded body having a desired shape. Then, in the third step, the solvent in the urethane is replaced with water to form continuous pores. The object having fine open cells formed in this way is
In the process of, the product is obtained after drying and the necessary finishing work.

The required finishing work differs depending on the final product, but in the case of the electrophotographic roller, a tubular molded body is obtained by extrusion molding or press molding, and after being dried to some extent, the shaft is inserted. Bonding is followed by drying and polishing operations.

The polishing operation is carried out for the purpose of improving the surface properties and improving smoothness and roundness in order to ensure uniform contact with the photosensitive drum.

The porous urethane obtained according to 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. Is also suitable as

As a solvent for dissolving the urethane elastomer, dimethylformamide (DMF), methyl ethyl ketone (MEK), etc. can be used. Carbon black is suitable as an additive for obtaining uniform conductivity. Further, as the 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 in order to form continuous pores in which a plurality of pores communicate with each other. The surfactant is conveniently hydrophilic.

[0029]

In this structure, the urethane elastomer and hydroxyethyl cellulose as the additive substance are mixed with the solvent (D
When dissolved in MF) and sufficiently kneaded, the additive substance is evenly dispersed in the urethane elastomer.

The resulting high-viscosity substance is used to form a basic molded body having a shape that allows for a final required shape, such as shrinkage due to drying and processing margin such as polishing.

After that, the solvent is removed to cure the molded body. Further immersion in water elutes the additive substance hydroxyethylcellulose, and the elution traces form fine pores.

On the surface of the molded body thus formed, extremely fine pores, for example, 8 μm or less and substantially uniform pores are dispersed. The diameter of the pores increases as the amount of solvent increases, and decreases as the amount of solvent decreases. The number of pores can be adjusted here by the amount of hydroxyethyl cellulose added.

[0033]

EXAMPLES Examples of the present invention will be described below.

Example 1 Polycarbonate urethane (manufactured by Sanyo Kasei Co., Ltd.) 10 to 20% by weight Methyl ethyl ketone (MEK) (manufactured by Nitto Kagaku Co., Ltd.) 30 to 50% by weight Surfactant (manufactured by Sanyo Kasei 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 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, a cylindrical basic molded body was formed by press molding, and then methyl ethyl ketone was evaporated to cure the molded product (second step in FIG. 1).

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

Example 2 The same material and process as in Example 1 were carried out except that 30 to 50% by weight of dimethylformamide (DMF) was used instead of the methyl ethyl ketone (MEK) of Example 1.

Since the dimethylformamide (DMF) used in this example does not evaporate, it was put in a water bath to elute the solvent. Also in this example, the surface of the molded product was confirmed after drying, but fine pores were obtained.

Example 3 A shaft was bonded to the center hole of the tubular molded article obtained in Examples 1 and 2 to form a roller. The finishing process was performed in the same manner as the conventional porous urethane roller. Therefore, it was confirmed that there is no particular increase in costs in the manufacturing / finishing process.

[0041]

As described above in detail, 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 is obtained by the substantially same process as the conventional process.

As a result, by forming the developing roller of various electrophotographic type devices by using the thus obtained porous urethane, the toner supply efficiency is improved, and it becomes possible to adopt fine toner particles, thereby making the pixel 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 hydroxyethyl cellulose added and the amount of solvent. Therefore, it is possible to sufficiently cope with the need to reduce the pore diameter size when using a finer toner in the future.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram showing a structure of a main part of an electrophotographic image forming section.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Chiaki Sekioka 1405 Daimaru Odaimaru, Inagi City, Tokyo Inside Fujitsu Aisotec Co., Ltd.

Claims (6)

[Claims] 1. A process of dissolving a polymer substance and a water-soluble and solvent-soluble plant fiber additive in a solvent, a process of adding a hydrophilic surfactant, and basic molding from the obtained high-viscosity material. A process for forming a product, a process for evaporating a solvent from the basic molded product to cure the product, and a process for leaching the vegetable fiber additive material by immersing the product in water, thereby producing a porous elastic body. . 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-based surfactant. 4. The method for producing a porous elastic body according to claim 1, wherein the solvent is dimethylformamide. 5. The method for producing a porous elastic body according to claim 1, wherein the solvent is methyl ethyl ketone. 6. A porous elastic body roller comprising a porous elastic body in which pores having an average pore diameter of 8 μm or less are dispersedly formed on the surface of the elastic body.