JPH0676500B2 - Rubber member for separation pad - Google Patents

Description

The present invention relates to a rubber member for a separation pad, and more particularly to a copying machine,
The present invention relates to a rubber member used as a separation pad forming a part of a paper feeding mechanism of various office automation equipment such as a printer or a facsimile.

[Conventional technology]

There are various types of paper feed mechanisms for various OA devices such as copiers, printers, and facsimiles.

For example, an example of the paper feeding mechanism will be described with reference to FIG. This paper feed mechanism (1) is a flat plate-like member which is arranged to face a paper feed roller (2) rotatably supported by a rubber and a paper feed roller (2) which is substantially in contact with the paper feed roller (2) as shown in FIG. And a separation pad (3).

In this paper feed mechanism (1), a large number of sheets of paper (4a) (4b) stored in a cassette (not shown) or the like in a stacked state are moved by the rotation of the paper feed roller (2) so that The sheets are sequentially fed one by one due to the frictional resistance between the conveying surface and the sheet (4a). At this time, in order to prevent the above-mentioned papers (4a) and (4b) from being double-fed and to reliably send out only one paper (4a), an undesired paper that has entered below the paper (4a) to be sent out. (Four
The separation pad (3) is brought into pressure contact with b) so that the pad surface (5) of the separation pad (3) and an undesired sheet (4b)
The undesired paper (4b) that has entered between the above-mentioned paper feed roller (2) and the separation pad (3) is separated from the paper (4a) to be sent out and stopped by the frictional resistance with.

Here, the separation pad (3) is used to form the paper (4a) (4b).
The necessary conditions to prevent double feeding of paper are as follows: friction coefficient between paper feed roller (2) and paper (4a) is μ ₁ , paper (4b)
If the coefficient of friction between the separation pad (3) and the separation pad (3) is μ ₂ , and the coefficient of friction between the paper (4a) and the paper (4b) is μ ₃ , then generally μ
_The relational expression ₁ > μ ₂ > μ ₃ holds.

By the way, a rubber member (6) is attached to the pad surface (5) of the separation pad (3) so that a predetermined frictional resistance with respect to the paper (4b) is obtained and the above relational expression is satisfied. In general, the rubber member (6) is conventionally made of urethane rubber, natural rubber, butadiene rubber,
The current situation is to use a sheet-shaped material such as chloroprene rubber.

[Problems to be Solved by the Invention]

In the paper feeding mechanism (1) described above, in order to ensure the feeding of the paper (4a) by the paper feeding roller (2), it is necessary to increase the friction coefficient of the paper feeding roller (2). Therefore, the composition of the paper feed roller (2) generally contains a large amount of process oil of 100 to 250 parts by weight per 100 parts by weight of rubber. On the other hand, since the rubber member (6) on the pad surface (5) of the separation pad (3) is in contact with the paper feed roller (2), the oil component contained in the paper feed roller (2) is rubber. Transfer to member (6). Of the rubber members (6), natural rubber, butadiene rubber, and the like are composed of rubber having poor oil resistance, so that the rubber member (6) swells with oil, which causes the paper feed roller (2). ), Each friction coefficient μ _{1 of} the paper (4a) (4b) and the separation pad (3),
mu _2, mu relation mu ₁ of between _3> μ _2> μ ₃ is not satisfied, there is a problem that smooth paper feeding becomes difficult. Further, there is a problem that urethane rubber, chloroprene rubber or the like among the rubber members (6) causes a squeal (abnormal noise) at the time of feeding.

Therefore, the present invention has been proposed in view of the above problems, and an object thereof is to maintain a separation function of a separation pad in a normal state and, at the same time, to form a composition that does not cause squeaking (abnormal noise). It is to provide a rubber member for a separation pad.

[Means for Solving the Problems]

Technical means for achieving the above object in the present invention is a rubber member forming the pad surface of a separation pad having a pad surface on which a member to be separated slides in a pressure contact state, the content of acrylic nirilto is 10 ~ 35% of acrylonitrile-butadiene rubber alone or acrylonitrile-
That is, the composition was obtained by crosslinking a mixture of butadiene rubber and another predetermined rubber.

Further, α, β-monoethylenically unsaturated carboxylic acid having 3 to 8 carbon atoms, a metal oxide or a hydroxide is added to the above rubber alone or a mixture, and a crosslinking reaction by an organic peroxide or carbon black is added. In addition, it is desirable that the composition be formed by a crosslinking reaction with sulfur.

[Action]

The rubber member for a separation pad according to the present invention can be improved in oil resistance by being composed of an acrylonitrile-butadiene rubber alone or a mixture of acrylonitrile-butadiene rubber and another predetermined rubber. Here, the more the content of acrylonitrile constituting the acrylonitrile-butadiene rubber is increased, the better the oil resistance is. However, on the other hand, squealing occurs when the separated member slides on the rubber member under pressure contact. If a phenomenon occurs or the cold resistance is lowered and the rubber member is solidified at the time of use in a low temperature state, the smooth separating operation becomes difficult. Therefore, by setting the content of the acrylonitrile to 10 to 35%, the oil resistance can be improved, and the squeaking phenomenon can be suppressed to improve the cold resistance.

Furthermore, the rubber alone or the mixture is added with an α, β-monoethylenically unsaturated carboxylic acid having 3 to 8 carbon atoms, a metal oxide or a hydroxide, and a crosslinking reaction with an organic peroxide,
Alternatively, by adding carbon black and forming a composition by a crosslinking reaction with sulfur, the friction coefficient between the member to be separated and the rubber member can be set to a desired value, and a smooth separating function can be realized.

〔Example〕

An example of the rubber member for a separation pad according to the present invention will be described below. The rubber member (6) of this embodiment is applied to the separation pad (3) used in the paper feeding mechanism (1) of the type shown in FIG.

First, the rubber member (6) of the present invention is composed of a unit of acrylonitrile-butadiene rubber (hereinafter simply referred to as NBR) or a mixture of NBR and another predetermined rubber (described later).
A single substance or NBR mixture is cross-linked by transfer molding, injection molding, press molding, extrusion molding or the like to form a sheet. Since the rubber member (6) is mainly composed of an NBR unit or a mixture having excellent oil resistance, oil is transferred from the paper feed roller (2) shown in FIG. 4 to the rubber member (6). However, the swelling of the rubber member (6) is suppressed. Here, the NBR is a copolymer of acrylonitrile and butadiene, and the higher the content of this acrylonitrile (hereinafter simply referred to as the AN amount), the better the oil resistance. However, on the other hand, paper (4b)
When the rubber slides on the rubber member (6) while being pressed by the paper feed roller (2), vibration occurs and resonates with the mounting member, and an unpleasant noise commonly called a squeaking phenomenon occurs. . Further, when the rubber member (6) has low cold resistance and is used in a low temperature state, the rubber member (6) solidifies, which makes it difficult to smoothly feed the paper.

Therefore, the AN amount in the rubber member (6) is set to 10 to 35%. When the rubber member (6) is composed of NBR alone, the AN content is 10 to 35% of NBR, and when it is composed of the NBR mixture, the AN content is relatively high. A large amount of NBR can be used, and the AN amount is 10 to 35% based on the total amount of the NBR mixed with other predetermined rubber. By setting the AN amount in the range of 10 to 35%, the oil resistance is excellent, and the squeaking phenomenon is suppressed and the cold resistance can be improved. According to the experiment result of the applicant, the AN amount is 10%.
It has been confirmed that the oil resistance is significantly reduced when the amount is less than 1.0%, and the squeaking phenomenon is likely to occur when the AN amount exceeds 35% .It has been found that the appropriate amount of AN is 10 to 35%. ing.
When the rubber member (6) is made of NBR mixture, the N
Other predetermined rubbers to be mixed with BR include natural rubber (N
R), butadiene rubber (BR), styrene butadiene rubber (SBR), etc., which does not easily cause the squeaking phenomenon and has excellent cold resistance. Here, urethane rubber, ethylene propylene rubber (EPDM), chloroprene rubber, chlorosulfonated polyethylene rubber, butyl rubber and the like, which easily cause a squeal phenomenon, are not suitable.

As described above, by composing the rubber member (6) in NBR units or a mixture containing 10 to 35% of AN, the oil resistance is excellent, so that the oil content from the paper feed roller (2) is reduced by the rubber member (6). It is possible to prevent the rubber member (6) from swelling even when it is transferred to 6), and as described in the related art, the paper feeding roller (2), the papers (4a) (4b) and the separation pad (3). The relational expression μ ₁ between each friction coefficient μ ₁ , μ ₂ , μ _{3 of}
> Μ ₂ > μ ₃ is established, and smooth paper feeding can be realized.

Further, according to the experiment result of the applicant, the paper feed roller (2)
It was confirmed that the friction coefficient μ ₁ of the paper (4a) was 1.5 to 2.5, and the friction coefficient μ _{3 of} the paper (4a) and the paper (4b) was 0.3 to 0.7. Therefore, in order to obtain the most suitable separation pad (3), the friction coefficient μ ₂ of the separation pad (3) and the paper (4b) is selected to be 0.7 <μ ₂ <1.5, preferably 0.75 to 1.35. There is a need to.

Therefore, the Applicant pays attention to the compounding agent used in the crosslinking reaction in forming the NBR unit or the mixture by crosslinking, and selects the compounding agent as described below, and thereby the optimum condition satisfying the above-mentioned conditions is obtained. A rubber member (6) was obtained. The crosslinking reaction basically includes the case where an organic peroxide is used and the case where sulfur is used (vulcanization reaction).

First of all, when an organic peroxide is used, it has 3 to 10 carbon atoms.
The NBR unit or mixture is cross-linked with the compounding agent to which the α, β-monoethylenically unsaturated carboxylic acid of 8, the metal oxide or hydroxide and the above organic peroxide are added.

Examples of the α, β-monoethylenically unsaturated carboxylic acid include methacrylic acid, acrylic acid, itaconic acid, crotonic acid and the like, and among them, the methacrylic acid is preferable. The content of the α, β-monoethylenically unsaturated carboxylic acid is set to 3 to 60 parts by weight, preferably 10 to 40 parts by weight, based on 100 parts by weight of the NBR unit or the mixture. Here, if the content is less than 3 parts by weight, a high hardness cannot be obtained, and if it exceeds 60 parts by weight, it becomes brittle and both are unsuitable.

Next, the metal oxide or hydroxide is for chemically reacting with the above-mentioned α, β-monoethylenically unsaturated carboxylic acid to produce a metal salt, and examples thereof include magnesium oxide. The content of this metal oxide or hydroxide is α, β-
Depending on the content of monoethylenically unsaturated carboxylic acid, 1 to 100 parts by weight of NBR unit or mixture
It is set to 60 parts by weight, preferably 10 to 40 parts by weight. Here, if the content is less than 1 part by weight, a high hardness cannot be obtained, and if it exceeds 60 parts by weight, it is unsuitable even if unreacted metal oxide or hydroxide remains.

Finally, examples of organic peroxides include perbenzoic acid, dicumyl peroxide, cumene peroxide, and benzoyl peroxide. Of these, dicumyl peroxide (DCP) is preferable. The content of the organic peroxide is set to 0.5 to 5 parts by weight based on 100 parts by weight of the NBR unit or the mixture. Here, if the content is less than 0.5 parts by weight, high hardness cannot be obtained and the physical strength becomes low,
Further, if it exceeds 5 parts by weight, it becomes brittle and unpractical and both are not suitable.

Incidentally, when crosslinking NBR alone or a mixture, in addition to the above-mentioned compounding agents, various reinforcing agents, fillers, pigments,
Antiaging agents and the like may be added within a range that does not adversely affect the physical properties of rubber.

Second, if sulfur is used, carbon black is added to the NRB unit or mixture and vulcanized with the sulfur.

As the carbon black, channel black,
Furnace black and the like, of which FEF and GPF are preferable. The content of this carbon black is set to 10 to 40 parts by weight based on 100 parts by weight of NBR alone or the mixture. Here, if the content is less than 10 parts by weight, a high hardness cannot be obtained, and if it exceeds 40 parts by weight, not only the workability is deteriorated but also the paper is contaminated, which is unsuitable.

Further, the content of sulfur is set to 1 to 3 parts by weight with respect to 100 parts by weight of the NRB alone or the mixture.

In addition to the above-mentioned compounding agents, various fillers such as antioxidants, plasticizers and vulcanization accelerators may be added within a range that does not adversely affect the physical properties of rubber.

Crosslinking reaction treatment with the organic peroxide or sulfur described above, NBR units or mixtures, and various compounding agents are uniformly kneaded with a kneader, internal mixer (Banbury), Brabender, rolls, etc., transfer molding,
It is carried out by thermal crosslinking by injection molding, press molding or the like. The heating temperature at the time of crosslinking is usually preferably set to 130 to 180 ° C., and if it is less than 130 ° C., the time required for the crosslinking reaction becomes long, and if it exceeds 180 ° C., the rubber physical properties such as deterioration resistance are deteriorated. Both are bad and unsuitable.

Next, based on an experiment conducted by the applicant, the compounding examples (A) to (J) of the present invention in which the NBR simple substance or the mixture was formed by a crosslinking reaction with an organic peroxide or sulfur, and comparison with this compounding example FIG. 1 shows an undesired formulation example (K) to (M) for achieving the above, and a table showing the hardness, oil resistance, friction coefficient μ ₂ and squealing degree of the rubber member (6) for each formulation example. .

In the crosslinking reaction treatment here, the heating temperature was set to 170 ° C. and the heating time was set to 30 minutes.

Further, the hardness of the rubber member (6) is based on JIS-K6301 [vulcanized rubber physical test method], where T _B is the tensile strength and E _B is the elongation rate until cutting.

Regarding oil resistance, ΔW represents the rate of increase in weight and ΔV represents the rate of increase in volume, which represents the degree of swelling of the rubber member (6). The smaller the measured value, the better the oil resistance. This oil resistance experiment was carried out by storing process oil at 40 ° C. in a container such as a beaker and immersing the rubber member (6) in this oil for 48 hours.

Further, the friction coefficient μ ₂ was measured by an experiment as shown in FIG. This is at the paper feeding part of the cassette (7) in which a large number of papers (4a) (4b) ...
Paper feed roller (2) with a diameter of 38 mm and a width of 40 mm and a length and width of 10 mm x 40
The separation pads (3) to which a rubber member (6) having a thickness of 2 mm and a thickness of 2 mm is attached are arranged to face each other, and the sheets (4a) (4b) ... Then, a load of 250 g is applied to the separation pad (3) by the bush pull gauge (8), and then the paper (4a) (4b) ... Is fed out at a speed of 150 mm / s by the rotation of the paper feed roller (2). The friction constant μ ₂ at the rubber member (6) of the separation pad (3) of Example ₂ was detected by the load cell (9).

Finally, the squealing degree was measured by an experiment as shown in FIG. The rubber member (6) was rubbed against a predetermined coated paper (10) fixedly arranged under a load of 2 to 3 kg to determine the squeaking ease. As the criteria for judgment, urethane rubber and ethylene propylene rubber (EPDM) which are easy to squeal were set to 5, and natural rubber (NR) and butadiene rubber (BR) which were hard to squeal were set to 0.

As is clear from the experimental results shown in FIG. 1, in the formulation examples (A) to (D), when the NBR simple substance is cross-linked with an organic peroxide, in the formulation examples (E) and (F), the NBR simple substance is sulfur. When vulcanized, the compounding examples (G) and (H) were obtained by crosslinking the NBR mixture with an organic peroxide, and the compounding examples (I) and (J) were obtained by vulcanizing the NBR mixture with sulfur. Show. On the other hand, formulation example (K)-
(M) shows the case where NBR, ethylene propylene rubber (EPDM) and urethane rubber, which are prone to squeal, are cross-linked with organic peroxide or sulfur.

The above-mentioned formulation examples (A) to (J) of the present invention are formulation examples (K) to
As is apparent from the comparison with (M), the oil resistance is excellent, the friction coefficient μ ₂ conforms to the above-described preferable range of 0.75 to 1.35, and the squealing degree is small.

Although the rubber member of the separation pad that constitutes a part of the paper feeding mechanism of the OA equipment has been described in the above embodiment, the present invention is not limited to this, and the separated member slides in a pressure contact state. It is applicable to the rubber member having the pad surface of the separation pad having the pad surface.

〔The invention's effect〕

According to the separation pad rubber member of the present invention, the oil resistance is excellent and the coefficient of friction with the member to be separated can be set to an appropriate value, so that the member to be separated can be smoothly separated. Also,
It is possible to minimize the current squeal that occurs when the separated members rub against each other, improve cold resistance, and use well in low temperature conditions. A rubber member for a separation pad can be provided.

[Brief description of drawings]

1 to 3 are for explaining an embodiment of the present invention. FIG. 1 is a diagram showing a list of compounding examples of rubber members, and FIG. 2 is an experiment for measuring a friction coefficient of rubber members. FIG. 3 is a configuration diagram showing an example, and FIG. 3 is a configuration diagram showing an experimental example for measuring the degree of squeaking of a rubber member. FIG. 4 is a block diagram showing an example of the paper feeding mechanism. (3) ... Separation pad, (4a) (4b) ... Separable member (paper), (5) ... Pad surface, (6) ... Rubber member.

Claims (2)

[Claims] 1. A rubber member forming a pad surface of a separation pad having a pad surface on which a member to be separated slides in a pressure contact state, wherein the content of acrylonitrile is 10 to 35%, and the rubber member is made of acrylonitrile-butadiene rubber. A rubber member for a separation pad, which is constituted by crosslinking a single substance or a mixture of acrylonitrile-butadiene rubber and another predetermined rubber. 2. The rubber alone or the mixture according to claim 1,
Be composed of a cross-linking reaction with sulfur by adding α, β-monoethylenically unsaturated carboxylic acid having 3 to 8 carbon atoms, a metal oxide or a hydroxide, and a cross-linking reaction with an organic peroxide, or carbon black. A rubber member for a separation pad, which is characterized by: