JPH07215519A - Paper separation roller - Google Patents

Abstract

PURPOSE:To provide a sheet separation roller capable of preventing stains on a document and having sufficient sheet separating force. CONSTITUTION:This sheet separation roller 1 is constituted of a mandrel 2, an elastic body layer 3 formed on the outer periphery of the mandrel 2, and a surface layer 4 made of a thermoplastic resin and formed on the outer periphery of the elastic body layer 3. The hardness Hs (JIS A) of the elastic body layer 3 is set to 20-80, and the friction coefficient against a sheet of the surface layer 4 is set to 0.15-0.45.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a plain paper copying machine (hereinafter referred to as
"PPC"), and a paper separating roller used in a paper feeding device such as a facsimile.

[0002]

2. Description of the Related Art In a sheet feeding device such as a PPC or a facsimile, in order to reliably feed sheets one by one, the sheet feeding device shown in FIGS.
As shown in FIG. 3, a system including a pickup roller 11, a pair of pulling rollers 12 and 12a, a paper feeding roller 15, and a paper separating roller 16 is adopted. Paper 1 in the above method
When one sheet of paper 3 is fed, as shown in FIG. 3, the paper separating roller 16 rotates in the opposite direction to the paper feeding roller 15 (rotates).
However, when two or more sheets of paper 13 are fed, as shown in FIG. 4, the paper separation roller 16 rotates in the same direction as the paper feed roller 15 so that the paper 13 is fed one by one reliably. Has become. At this time, the friction coefficient μ ₁ between the paper separation roller 16 and the paper 13 is set to be larger than the friction coefficient μ ₂ between the papers 13 and smaller than the friction coefficient μ ₃ between the paper feed roller 15 and the paper 13.

Further, in order to separate the papers 13 one by one, it is necessary to have a separation force equal to or more than the force obtained by adding both the friction coefficient μ ₂ between the papers 13 and the physical adhesive force of the cut surface of the paper 13. Become. Since this separating force usually requires μ ≧ 1.0, a material is used so that the friction coefficient μ ₁ between the paper separating roller 16 and the paper 13 satisfies μ ₁ ≧ 1.0 from the initial state to the roller replacement time. is doing.

On the other hand, the ADF (automatic document feeder) system used for PPC and facsimile is
Rarely do you pass a blank sheet of paper, usually a copied original, ink, or an original written with a pencil. At this time, in the case of an original written with a pencil, the graphite of the pencil is scraped off due to rubbing between the paper separating roller having a large friction coefficient (μ ₁ ≧ 1.0) and the paper, and the original is soiled. There was a problem that dirt was transferred to the original document.

[0005]

In order to solve the above problems, it is conceivable to reduce the friction coefficient μ ₁ between the paper separating roller and the paper (0.3 or less), but the paper separating force becomes small. , It is not possible to reliably feed paper one by one.
Further, in order to reliably feed the paper one by one, if the friction coefficient μ ₁ between the paper separating roller and the paper is increased (1.0 or more),
The rubbing between the paper separating roller and the paper causes a problem that the graphite of the pencil is scraped off and the original becomes dirty, or the dirt is transferred to the next original.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a paper separating roller capable of preventing a document from being contaminated and having a sufficient paper separating force in an ADF system.

[0007]

The present invention comprises a cored bar, an elastic body layer formed on the outer periphery of the cored bar, and a thermoplastic resin surface layer formed on the outer periphery of the elastic body layer. In the paper separating roller, the hardness Hs (JIS A) of the elastic layer is 2
The gist is a paper separating roller having a surface friction coefficient of 0 to 80 and a paper friction coefficient of 0.15 to 0.45.

Examples of the material for forming the elastic layer include polyolefin rubbers such as ethylene propylene rubber, chlorinated polyethylene and chlorosulfonated polyethylene. And, this polyolefin rubber contains a vulcanizing agent,
Additives such as a vulcanization accelerator, a reinforcing agent, and a softening agent are appropriately mixed. Further, polynorbornene or polyurethane can be used as the material for forming the elastic layer. The hardness Hs (JIS A) of the elastic layer needs to be in the range of 20 to 80, and is preferably in the range of 30 to 60. This is because when the hardness Hs (JISA) of the elastic layer is less than 20, there is a problem in moldability and a satisfactory paper separating roller cannot be obtained, and when it exceeds 80, the function as an elastic body is not obtained.

Examples of the thermoplastic resin forming the surface layer include polyethylene, polypropylene, vinyl chloride, polyethylene terephthalate (PET), polyamide, fluororesin, urethane resin and the like, but N-methoxymethylated nylon (8 -Nylon) is used.
It is necessary to use a surface layer having a coefficient of friction with paper of 0.15 to 0.45. This is because if the surface friction coefficient against paper is less than 0.15, good paper separability cannot be obtained, and if it exceeds 0.45, the problem of document smearing occurs. The thickness of the surface layer is preferably 3 to 15 μm from the viewpoint of paper separability and document stain.

The paper separating roller of the present invention can be manufactured, for example, as follows. That is, an adhesive is applied to the outer peripheral surface of the cored bar, and the elastic body layer is formed by die vulcanization using the elastic body layer forming material. Next, the thermoplastic resin forming the surface layer is dissolved in a suitable solvent and the outer peripheral surface of the elastic layer is coated by spraying, dipping or the like to obtain a paper separating roller. As a method of forming the surface layer on the outer peripheral surface of the elastic layer, a tube made of a thermoplastic resin may be press-fitted in addition to the coating. With the above structure, the rubbing force between the paper separating roller and the original becomes very small due to the surface layer. Moreover, since the hardness of the elastic layer is low, the contact area is widened, and the apparent friction coefficient (μ ₁ ) can be increased.

[0011]

The paper separating roller of the present invention has the hardness H of the elastic layer.
Since s (JIS A) is set to 20 to 80 and the surface friction coefficient to paper is set to 0.15 to 0.45, the rubbing force between the paper separating roller and the paper is very small due to the surface layer having a small friction coefficient to paper. And the hardness Hs of the elastic layer (JIS
Since A) is low, the contact area becomes large and the apparent friction coefficient (μ ₁ ) can be increased.

[0012]

Examples 1 to 6 As shown in Table 1, ethylene propylene rubber was used as the elastic layer forming material and N-methoxymethylated nylon (8-nylon) was used as the surface layer forming material. The shown paper separating roller 1 was produced.

[0013]

[Table 1]

First, an elastic body layer 3 was formed on the outer periphery of a core metal 2 made of a metal shaft having a diameter of 6 mm by using the above-mentioned ethylene propylene rubber so as to have an outer diameter of 20 mm by mold vulcanization. Next, the outer periphery of the elastic layer 3 is coated with a resin liquid of 8-nylon and dried to 10 μm.
Was formed on the surface layer 4. In Examples 1, 3 and 5, citric acid was added to the 8-nylon resin solution to perform a curing treatment to form a surface layer, and the friction coefficient was about 0.4.
Adjusted so that In Examples 2.4 and 6, citric acid was added to the 8-nylon resin solution to perform a curing treatment to form a surface layer, and the friction coefficient was adjusted to about 0.2.

[0015]

Comparative Examples 1 to 7 As shown in Table 2, ethylene propylene rubber was used as the elastic layer forming material, and N-methoxymethylated nylon (8-nylon) was used as the surface layer forming material. A paper separating roller was produced in the same manner.

[0016]

[Table 2]

In Comparative Examples 1, 3 and 5, citric acid was added to the 8-nylon resin solution and a curing process was performed to form a surface layer, and the friction coefficient was adjusted to about 0.1. did. In Examples 2.4 and 6, the resin solution of 8-nylon was used as it was without being subjected to a curing treatment to form a surface layer.
Further, in Comparative Example 7, a paper separating roller was produced by forming only the elastic layer without forming the surface layer.

With respect to the products of the above Examples and Comparative Examples, the hardness (Shore D), the coefficient of friction, the paper separability, and the original smearing property were evaluated. The following methods were used to evaluate the coefficient of friction, paper separability, and original stain resistance.

[Frictional Coefficient] As shown in FIG. 5, the measurement paper 19 is sandwiched between the paper separation roller 1 and the push-up plate 17, and 3
Pressing with a force of 00gf, paper separating roller 1
Was measured at the peripheral speed of 180 mm / sec as indicated by the arrow by the load cell 18.

[Paper Separation] Under high temperature and high humidity environment (35 ° C. × 9
(0%), a 1000-sheet paper passing test was conducted with a copying machine, and the number of occurrences of double feeding was evaluated. When the occurrence of double feeding was 10 times or less, the result was ◯, and when the occurrence of double feeding was 11 times or more, the result was x.

[Original Staining Property] Pencil original (density: B) was evaluated by rubbing a pencil when the paper was passed. When there was almost no rubbing, the mark was ○, and when the character was deformed or became unreadable due to rubbing, the mark was X.

From the results shown in Tables 1 and 2, the papers of Examples are good in both the paper separating property and the original smearing property, whereas the comparative products have a problem in one of the paper separating property and the original smearing property. there were.

[0023]

In the paper separating roller of the present invention, the hardness Hs (JIS A) of the elastic layer is set to 20 to 80, and the friction coefficient of the surface layer against the paper is set to 0.15 to 0.45. It can be prevented and has sufficient paper separation force.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a paper separating roller of the present invention.

FIG. 2 is a vertical sectional view of a paper separating roller of the present invention.

FIG. 3 is a diagram showing a usage state of a paper separating roller.

FIG. 4 is a diagram showing a usage state of a paper separating roller.

FIG. 5 is an explanatory diagram showing a method of measuring a friction coefficient.

[Explanation of symbols]

 1: Paper separation roller 2: Core metal 3: Elastic layer 4: Surface layer

Claims (1)

[Claims] 1. A paper separating roller comprising a cored bar, an elastic body layer formed on the outer periphery of the cored bar, and a thermoplastic resin surface layer formed on the outer periphery of the elastic body layer. Has a hardness Hs (JIS A) of 20 to 80 and a friction coefficient of the surface layer with respect to paper of 0.15 to 0.45.