JP2002293448A - Paper feeding roller and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeding roller improved in compression permanent deflection and the paper feeding force and having excellent durability without generating a clogging by the paper chips and the toner and without giving a damage to the paper and an image on the paper, and to provide an image forming device provided with the same. SOLUTION: This paper feeding roller is formed by arranging a rubber foaming body, desirably, an ethylene propylene rubber foaming body having Asker C hardness of 15-40 degree and compression permanent deflection of 15% or less, and the image forming device is formed by installing this paper feeding roller. As a raw material of the ethylene propylene rubber foaming body, ethylene propylene rubber having iodine of 35-45 and Mooney viscosity ML1+4 at 100 deg.C of 20-50 is desirably used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feed roller and an image forming apparatus equipped with the same, and more particularly, to an image forming apparatus such as an electrophotographic apparatus such as a copying machine, a facsimile, and a printer, or an electrostatic recording apparatus. The present invention relates to a paper feed roller mounted on an apparatus and an image forming apparatus equipped with the paper feed roller.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, a facsimile, and a printer, paper is used as a final image carrier. After these papers are taken into the image forming apparatus, predetermined printing (printing) is performed on the paper surface, and when the paper is finally taken out from the image forming apparatus, paper feeding, charging, conveyance, charge removal, shape correction, and the like are performed. And paper feed rollers are used for that purpose. As the paper feed roller, rubber foams such as urethane rubber, silicone rubber, and ethylene propylene rubber are often used so as to have a large conveying force and not to damage paper and images on the paper surface.

However, these rubber materials have advantages and disadvantages and have not always been satisfactory. For example,
Urethane rubber foam is made of relatively inexpensive raw materials, has a large frictional force for paper feeding, and has a small permanent compression set. However, it is susceptible to heat, ozone, and nitrogen oxides (NOx). There is a disadvantage that it is easy. Further, the silicone rubber foam is resistant to heat, ozone, and NOx, and is resistant to paper dust and has durability. However, it has the disadvantage that the raw material is expensive and the frictional force for paper feeding is small. On the other hand, ethylene propylene rubber foam is relatively inexpensive in raw materials,
The frictional force for paper feeding is large, and it is strong against heat, ozone, and NOx, and it is durable. However, the permanent compression strain is large, and the foam cells are relatively large, and paper powder and toner are likely to adhere to foam cells on the surface. There were drawbacks. Therefore, the paper feed roller made of the ethylene propylene rubber foam is deformed when it is kept in contact with other members for a long period of time, and as a result, there is a problem that a paper feed failure occurs.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a durable paper feed roller which is made of inexpensive raw materials, has an improved compression set, and has small foam cells. It is intended for. Still another object of the present invention is to provide an image forming apparatus equipped with the improved paper feed roller.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, the Asker C hardness is in the range of 10 to 40 ° and the compression set is 15% or less. It has been found that a paper feed roller made of a rubber-rubber foam can achieve an intended purpose. further,
Ethylene propylene rubber, particularly an iodine value of 35 to 45, and Mooney viscosity ML as a raw material rubber for the rubber foam.
_When an ethylene propylene rubber having a _{1 + 4} (100 ° C.) of 20 to 50 is used, the compression set is further improved and a rubber foam having fine foam cells can be obtained stably. I found it to be excellent. The present invention has been completed based on such findings. That is, according to the present invention, the outer periphery of the shaft has a hardness of 10 to 40 ° in Asker C hardness and a compression set of 15%.
The present invention provides a paper feed roller provided with the following rubber foam. The present invention also provides an image forming apparatus equipped with the paper feed roller.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The paper feed roller of the present invention has a rubber having an Asker C hardness of 10 to 40 ° and a compression set of 15% or less as an elastic layer on the outer periphery of a shaft. A foam is provided. 1 to 3 show specific examples (transverse cross-sectional views of the rollers) of the paper feed roller of the present invention. In the figure, 1 is a shaft, and 2 is a rubber foam. In the paper feed roller of the present invention, the outer periphery of the shaft 1 may be continuously covered with a rubber foam 2 as shown in FIG. May be intermittently or partially covered with the rubber foam 2 or, as shown in FIG. 3, the outer periphery of the shaft body 1 may be continuously covered with the rubber foam 2 having a ridge. In short, it is only necessary to adopt a mode in which the paper can be smoothly fed, and the shape is not particularly limited. Various materials can be used as the material of the shaft constituting the shaft core of the paper feed roller of the present invention, but usually, either metal or hard synthetic resin is suitably used.

On the other hand, there are various types of rubber foams disposed on the outer periphery of the shaft body, and ethylene propylene rubber foams are particularly preferable. Also, as this rubber foam,
Those having a Asker C hardness of 10 to 40 °, particularly preferably 15 to 35 ° are used. If the hardness is too low, the paper feeding force decreases and the compression set increases, which is not preferable. On the other hand, if the hardness is too high, the paper or an image formed on the paper surface is damaged, which is not preferable.

The rubber foam, preferably an ethylene propylene rubber foam, having a compression set of 15% or less is effective in increasing the paper feeding force and stably maintaining it for a long period of time. In particular, those having 10% or less are optimal. If the compression set is larger than 15%, it may cause a problem particularly in paper feeding after being left unattended, which is not preferable. Further, the ethylene propylene rubber foam has an iodine value of 35 to 45 and 10
The _one using an ethylene propylene rubber having a Mooney viscosity ML _{1 + 4} of 20 to 50 at 0 ° C. reduces the compression set of the foam, increases the ozone resistance, etc., and makes the cell diameter appropriate. It is more preferable from the viewpoint of maintaining the density in an appropriate range. This ethylene propylene rubber foam has an average foam cell diameter of 30 to 10
0 μm, and the number of foam cells is 100 to 1200 /
Those having a range of 25 mm have an average foam cell diameter of 5
0 to 80 μm, and the number of foam cells is 300 to 500
The one in the range of 25 / mm is preferred from the viewpoints of increasing the paper feeding force and preventing clogging of paper dust, toner and the like.

The ethylene propylene rubber foam used in the present invention may be any foam having the above-mentioned properties. Preferably, the raw material rubber has an iodine value of 35 to 45 as described above and a temperature of 100 ° C. Is manufactured using an ethylene propylene rubber having a Mooney viscosity ML _{1 + 4} of 20 to 50. Here, the components other than the raw rubber component may be appropriately selected, but preferably the raw rubber 1
(A) 0.5 to 5 parts by weight of a vulcanizing agent,
(B) 1 to 15 parts by weight of a foaming agent, (C) process oil 1
It can be obtained by adding 0 to 80 parts by weight and (D) 10 to 60 parts by weight of a filler and vulcanizing and foaming. In the case where the ethylene propylene rubber foam used in the present invention is to be made conductive, (E) conductive materials 1 to
Vulcanization and foaming may be performed by adding 80 parts by weight.

Although various vulcanizing agents can be used as the component (A), the foaming and vulcanization of the ethylene propylene rubber composition comprising the above-mentioned components can be easily controlled. And sulfur-based vulcanizing agents are preferred. Here, the sulfur-based vulcanizing agent refers to a combination of sulfur and a vulcanization accelerator or a sulfur-containing organic compound. Examples of the vulcanization accelerator include thiazoles, sulfenamides, thioureas, thiurams, dithiocarbamates, guanidines, aldehydeamines, and aldehyde ammonias. These may be used alone or in combination of two or more. They can be used in combination. Examples of the sulfur-containing organic compound include morpholine disulfide, tetraalkylthiuram disulfide, dipentamethylenethiuram tetrasulfide, and the like. The amount of the vulcanizing agent is preferably 0.5 to 5 parts by weight based on 100 parts by weight of the ethylene propylene rubber.

As the foaming agent of the component (B), for example,
azo compounds such as p, p'-oxybis (benzenesulfonyl hydrazide) (OBSH), benzenesulfonyl hydrazide, toluenesulfonyl hydrazide, etc .; azo compounds such as azodicarbonamide (ADCA) and azobisisobutyronitrile; Dinitrosopentamethylenetetramine, N, N'-dimethyl-N,
Organic blowing agents such as nitroso compounds such as N'-dinitrosoterephthalamide; and inorganic blowing agents such as sodium bicarbonate and ammonium bicarbonate. Among them, OB
SH, ADCA or a foaming agent using them in combination is preferable. The amount of the foaming agent added is ethylene propylene rubber 10
1 to 10 parts by weight, preferably 3 to 8 parts by weight, based on 0 parts by weight. It is preferable that the particle diameter of the foaming agent be as small as possible in order to reduce the size of the foam cells. The particle diameter of the blowing agent is preferably 10 μm or less, and 5 μm
The following are particularly preferred.

As the process oil of the component (C), paraffin-based process oil, naphthene-based process oil and aromatic-based process oil can be used.
Among these, a paraffin-based process oil is preferable because it does not contaminate other members such as a photoconductor. The addition amount of the process oil is preferably 20 to 70 parts by weight, and more preferably 40 to 70 parts by weight based on 100 parts by weight of the ethylene propylene rubber.
Part by weight is particularly preferred. 20 process oils added
If the amount is less than the weight part, the viscosity of the rubber composition becomes large and the processability becomes poor, and the foaming becomes insufficient, so that the density of the foam becomes large. On the other hand, if the amount of the process oil exceeds 70 parts by weight, the viscosity of the unvulcanized rubber composition becomes too low, and foaming occurs excessively, which causes a disadvantage that cells become coarse.

Examples of the filler of the component (D) include calcium carbonate, magnesium carbonate, silica, magnesium silicate, and clay. Of these, calcium carbonate is preferred from the viewpoint of stabilizing the foam cells. The addition amount of the filler is preferably from 10 to 60 parts by weight, particularly preferably from 20 to 50 parts by weight, based on 100 parts by weight of the ethylene propylene rubber. If the amount of the filler is less than 10 parts by weight, the foam cells are not stable and become non-uniform, and if the amount of the filler exceeds 60 parts by weight, the compression set of the ethylene propylene rubber foam is large. turn into.

The conductive material of component (E) used to impart conductivity to rubber foams, particularly ethylene propylene rubber foams, includes conductive carbon blacks such as Ketjen black and acetylene black; SAF, ISAF, H
Carbon black for rubber such as AF, FEF, GPF, SRF, FT, MT; carbon black for ink such as carbon oxide black; pyrolytic carbon black, graphite; conductive metal oxide such as tin oxide, titanium oxide and zinc oxide Metals such as nickel and copper; carbon whiskers;
Examples include conductive whiskers such as graphite whiskers, titanium carbide whiskers, conductive potassium titanate whiskers, conductive barium titanate whiskers, conductive titanium oxide whiskers, and conductive zinc oxide whiskers. The amount of the conductive material to be added is preferably from 1 to 80 parts by weight, particularly preferably from 5 to 60 parts by weight, per 100 parts by weight of the ethylene propylene rubber. By adding the above conductive material, the ethylene propylene rubber foam of the present invention is converted into a volume resistivity of 10 ⁴ to 10.
It can be adjusted to ¹⁰ Ω · cm. In the rubber foam used in the present invention, in addition to the above-mentioned additives, zinc vulcanization, vulcanization accelerating aids such as stearic acid, scorch inhibitors, tackifiers,
Other additives for rubber can be appropriately added as long as the effects of the present invention are not impaired.

An example of the method for manufacturing the paper feed roller of the present invention is as follows. First, rubber,
Preferably, additives other than the vulcanizing agent and the foaming agent are kneaded with the ethylene propylene rubber at a temperature of about 110 to 180 ° C. using a kneader, a Banbury mixer or the like. After cooling the kneaded product, a vulcanizing agent and a foaming agent were added, and 50
The rubber composition is obtained by kneading at a temperature of about 90 ° C. Next, this rubber composition is extruded into a cylindrical shape using an extruder, and cut into a predetermined length. A dummy shaft (temporary shaft) is inserted into a cylindrical object, and is set in a preheated mold.
(About 30 minutes). In order to obtain a foam having uniform and fine foam cells, it is important to mold the above-mentioned cylindrical material so that it is filled in a mold without gaps. In order to obtain a foam having uniform and fine foam cells, the pressure applied to the mold is also important, and 9.8 × 10 ^{5 to} 9.8 × 10
⁶ Pa (about 10 to 100 kg / cm ² ) is preferable, and 1.9 × 10 ^{6 to} 7.9 × 10 ⁶ Pa (about 20 to 80 k
g / cm ² ) is particularly preferred. As a heating method for obtaining a foam, there are a high frequency method, a hot air method, a fluidized bed method, a vulcanizing can method and the like in addition to the above-mentioned mold method. Among these heating methods, the mold method is particularly preferable because a rubber foam having uniform and fine foam cells and a small compression set can be obtained.

After heating at the predetermined temperature for a predetermined time, the mold is opened to obtain a rubber foam, particularly an ethylene propylene rubber foam. After removing the dummy shaft, instead of the dummy shaft, insert the main shaft (shaft) coated with an adhesive in advance and heat it with hot air or the like to bond the rubber foam with the shaft, and remove the foam. Post vulcanization is performed simultaneously. The temperature and time in this case are 140 to 20
0 ° C., about 15 to 60 minutes. The outer periphery of the foam with the shaft is adjusted to a desired outer diameter by grinding with a grindstone, peeling with a blade, or the like to obtain a target paper feed roller. After this, it is preferable to further perform an annealing treatment to remove the internal stress remaining on the roller, since the compression set becomes smaller. The annealing temperature and time are as follows:
70-200 ° C., about 15-300 minutes. The paper feed roller of the present invention, in addition to the above-described manufacturing method, can also be manufactured by injecting a rubber composition into a mold in which a dummy shaft is set, using an injection molding machine instead of an extruder, and heating and foaming the rubber composition. it can. The paper feed roller of the present invention thus obtained is mounted on an image forming apparatus, and supplies paper,
It effectively functions for paper charging, paper conveyance, paper static elimination, paper shape correction, etc., and can stably transfer (print or print) a clear image to paper for a long period of time.

[0017]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The physical properties of the paper feed rollers obtained in each example were measured according to the following methods. (1) Physical Properties of Rubber Foam (a) Cell Diameter and Number of Cells Using a CCD video camera manufactured by Hilox, about 70
Photographs were taken at double magnification, and the cell diameter and cell number of the image were measured. (B) Asker C hardness Measured according to JIS K6301. (C) Density The weight of the rubber foam in the air was divided by the volume. (D) Compression set Measured in accordance with JIS K 6382 (Home Rubber for Cushion). (E) Volume resistivity The volume resistivity ρ was calculated from the following resistance of the paper feed roller by the following equation. R = (ρr ₂ / Ld) ln (r ₂ / r ₁ ) where R: resistance of paper feed roller ρ: volume specific resistance of rubber foam L: contact length in axial direction d: nip width r ₁ : shaft Radius r ₂ : outer radius of paper feed roller ln: natural logarithm (2) resistance of paper feed roller A load of 500 g is applied to both ends of the roller under test and pressed onto a copper plate to obtain a resistivity meter R8340A (manufactured by Advantest Co.) ), A voltage of 100 V was applied to measure the resistance value.

Example 1 The components shown in Table 1 were kneaded with 100 parts by weight of EPDM having an iodine value of 36 and a Mooney viscosity ML _{1 + 4} (100 ° C.) of 39 using a kneader to obtain an unvulcanized mixture. A rubber foam composition was prepared. The rubber foam composition was formed into a tube (4 mm in inner diameter, 20 mm in outer diameter, 24 mm in length) using an extruder.
0 mm). A stainless steel dummy shaft (4 mm in diameter, 300 mm in length) is passed through the tube-shaped material, and vulcanized at 170 ° C. for 15 minutes in a cylindrical mold.
Foaming was performed to obtain a tubular foam. This tubular foam was put into an air oven and post-cured at 180 ° C. for 1 hour. The dummy shaft was removed from the tubular foam, and a metal shaft (outer diameter: 6 mm) wrapped around a hot melt adhesive was pressed into the tubular foam.
After heating and bonding at 20 ° C. for 70 minutes, the surface is polished after cooling, and a paper feed roller (outer diameter: 12 mm, length: 220 m)
m). Table 1 shows the physical properties of the paper feed roller.

Comparative Example 1 EPDM having an iodine value of 26 and Mooney viscosity ML _{1 + 4}
Paper feed roller (outer diameter 12 mm, length 220 m
m). Table 1 shows the physical properties of the paper feed roller. Comparative Example 2 EPDM having an iodine value of 26 and Mooney viscosity ML _{1 + 4}
Example 1 except that (100 ° C.) 100 was used.
Paper feed roller (outer diameter 12 mm, length 220
mm). Table 1 shows the physical properties of the paper feed roller.

[0020]

[Table 1]

(Note) (1) Iodine value is 36, Mooney viscosity ML _{1 + 4} (100
EPDM with 39 ° C) (2) Iodine value 26, Mooney viscosity ML _{1 + 4} (100
(C) 45, EPDM (3) Iodine value 26, Mooney viscosity ML _{1 + 4} (100
(C) 100 (4) Tokai Carbon Co., Ltd., TB # 5500 (5) Nitto Powder Chemical Co., Ltd., Novelite A (6) Idemitsu Kosan Co., Ltd., Dianaprosena oil PW90 (7) 2-mercaptobenzothiazole (8) Neocelbon N # 5000 manufactured by Eiwa Chemical Industry Co., Ltd.
[P, p'-oxybis (benzenesulfonylhydrazide)]

[0022]

The paper feed roller of the present invention has a small compression set, a large paper feed force, no clogging of paper dust and toner, and no damage to paper or paper images. The image forming apparatus equipped with the paper feed roller can transfer a clear image stably to paper for a long period of time, and can be smoothly printed from paper supply to paper conveyance and discharge without paper jam. Can be done.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of a paper feed roller of the present invention.

FIG. 2 is a cross-sectional view showing another example of the paper feed roller of the present invention.

FIG. 3 is a cross-sectional view showing still another example of the paper feed roller of the present invention.

[Explanation of symbols]

 1: Shaft 2: Rubber foam

Continued on the front page F term (reference) 3F049 AA10 CA11 LA02 LA05 LA07 LB01 3J103 AA02 AA12 AA36 AA63 BA41 FA03 FA07 FA12 FA14 FA23 GA02 GA57 GA58 GA60 HA03 HA12 HA53 4F074 AA25 AA97 AC02 AC26 BA18 BB01 CC24 DA03 CC04 DA09 DA24 DA59

Claims (5)

[Claims] 1. The hardness of the outer periphery of the shaft body is 1 as Asker C hardness.
A paper feed roller provided with a rubber foam having a compression set of 15% or less at 0 to 40 °. 2. The paper feed roller according to claim 1, wherein the rubber foam is an ethylene propylene rubber foam. 3. An ethylene propylene rubber foam comprising an ethylene propylene rubber having an iodine value of 35 to 45 and a Mooney viscosity ML _{1 + 4 at} 100 ° C. of 20 to 50 as a raw material rubber. Paper feed roller as described. 4. The paper feed roller according to claim 2, wherein the ethylene propylene rubber foam has an average foam cell diameter of 30 to 100 μm and a number of foam cells of 100 to 1200/25 mm. 5. An image forming apparatus comprising the paper feed roller according to claim 1.