JP4870486B2 - Paper sheet double feed prevention member - Google Patents

Description

  The present invention relates to a paper sheet multi-feed prevention member used for a paper feed mechanism, and in particular, prevents a double feed reliably, prevents occurrence of noise (abnormal noise) and improves wear resistance in a well-balanced manner. To achieve.

In a paper feeding mechanism in an ink jet printer, laser printer, electrostatic copying machine, plain paper facsimile machine, automatic deposit payment machine (ATM), etc., as shown in FIG. The paper feed roller 2 and the plate-like double feed prevention member 3 are arranged to face each other. Due to the frictional resistance between the double feed preventing member and the paper sheets, double feed in which two or more paper sheets are simultaneously fed is prevented.
Specifically, in order to prevent double feed, the friction coefficient μ1 between the paper and the paper feed roller, the friction coefficient μ2 between the paper and the double feed prevention member, and the friction coefficient μ3 between the stacked papers. Is required to satisfy the relationship of μ1>μ2> μ3.
Furthermore, the paper separation performance is required to be stable, and the double feed prevention member is required to have excellent durability such as ozone resistance and wear resistance.
In addition, the paper feed mechanism uses various types of paper such as plain paper, resin-coated paper, and OHP paper, so the double feed prevention member reliably separates the paper one by one for any paper. It is required to do.

However, when paper sheets having a synthetic resin surface such as an OHP film or resin-coated paper are used, there is a tendency that the multi-feed preventing member made of an elastomer composition and the paper sheets are in close contact with each other. There is a tendency that “non-feed” that is a conveyance failure of leaves is likely to occur. Also, due to the close contact between the two, there is a tendency that an unpleasant noise called “squeal” is generated when the two rub against each other and vibrate during paper feeding.
In addition, when the conveyed paper sheet and the double feed preventing member are rubbed, the friction coefficient between the two becomes very large, which causes a problem that the wear of the double feed preventing member is further increased.

  In order to solve these problems, Japanese Patent Application Laid-Open No. 2002-255384 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2002-96939 (Patent Document 2) mix cork and nylon fiber with a multifeed preventing member to obtain OHP paper. To prevent close contact.

However, when cork or nylon fiber is blended, the friction coefficient tends to decrease not only on OHP paper but also on plain paper, and in addition, the adhesion with OHP paper is not sufficient.
Furthermore, when the cork is blended, the cork is pulverized and then crushed cork of a certain particle range that is sieved through a mesh. There is a problem that the coefficient and the pad surface state are not stable. In addition, since cork cannot exhibit the effect of preventing adhesion of OHP paper or the like unless it is blended in a large amount, there is a problem in terms of cost.

  As described above, it is difficult for the conventional multi-feed preventing member to satisfy the required friction coefficient, wear resistance, and durability with respect to various papers such as plain paper and OHP paper. Therefore, there is a demand for providing a multifeed prevention member having better performance.

JP 2002-255384 A JP 2002-96939 A

  The present invention has been made in view of the above problems, and has a durability and wear resistance, and the paper feeding performance of a sheet made of a resin such as OHP paper in addition to plain paper is stable. It is an object of the present invention to provide a paper sheet multi-feed prevention member that can prevent the occurrence of squeal.

In order to solve the above problems, as a first invention, 0.5 to 9 parts by mass of acrylic beads are blended in a polyester-based thermoplastic elastomer, and the acrylic beads are dispersed in the polyester-based thermoplastic elastomer and on the surface. There is provided a paper sheet multi-feed preventing member comprising an exposed sheet-like separation pad .
Further, as a second invention, EPDM rubber and polypropylene are blended in such a manner that (EPDM / polypropylene) is 50/50 or more and 75/25 or less, and acrylic beads are blended in 1 to 4% by mass of the entire composition. Further, there is provided a paper sheet multi-feed preventing member comprising a sheet-like separation pad in which EPDM rubber and acrylic beads are dispersed in the polypropylene and exposed on the surface.

The composition for forming the paper sheet multi-feed prevention member, the cross-linking agent if necessary, reinforcing agents, various additives such as fillers.

The acrylic beads are fine particles having appropriate hardness and compression recovery, and when included in a multifeed prevention member, the friction coefficient with plain paper does not decrease, OHP paper, resin coated paper sheets and the like Demonstrates excellent properties that make it difficult to adhere and prevent double feeding.
That is, the acrylic beads are dispersed in the polyester-based thermoplastic elastomer or polypropylene, and a part of the acrylic beads is exposed on the surface of the multifeed prevention member. The exposed acrylic beads directly rub against the paper sheet, and the surface of the OHP paper or the like. Can prevent the paper sheet made of synthetic resin and the surface of the multi-feed preventing member from sticking to each other. As a result, while maintaining the friction coefficient for plain paper in an appropriate range, the friction coefficient for paper sheets such as OHP paper can be lowered to an appropriate range, and double feeding can be prevented for both. it can. In addition, since a large vibration does not occur between the multifeed prevention member and various paper sheets, the occurrence of squealing is also prevented.
Furthermore, the addition of acrylic beads prevents the double feed prevention member itself from being worn even during long-term use, and maintains a stable conveying force. And acrylic beads excellent in heat resistance and chemical resistance, since the excellent dispersibility, the existing methods, the rubber component and d elastomer component, additives and the like and mixed, can be kneaded and the like, the sheet The double feed preventing member can be easily formed.

In the first aspect of the invention, 0.5 to 9 parts by mass of acrylic beads are blended with the polyester-based thermoplastic elastomer. If the amount exceeds 9 parts by mass , the friction coefficient becomes too small and double feeding occurs from the initial stage of use. It is easy to do. More preferably 5% by mass or less, and particularly preferably 4% by mass or less. The lower limit of the amount of acrylic beads added is 0.5 parts by mass .

The acrylic beads are obtained by polymerizing monomers mainly composed of acrylic esters such as methyl acrylate, ethyl acrylate and butyl acrylate, and methacrylic esters such as methyl methacrylate, ethyl methacrylate and butyl methacrylate. The organic fine particles are preferably spherical.
Specifically, polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, polymethyl acrylate, polyethyl acrylate, polybutyl acrylate, crosslinked polymethyl methacrylate, crosslinked polyethyl methacrylate, crosslinked polymethacrylate Resins such as butyl acid, cross-linked polymethyl acrylate, cross-linked polyethyl acrylate, and cross-linked polybutyl acrylate are preferably used.
In particular, polymethacrylate-based acrylic beads such as polymethyl methacrylate, polyethyl methacrylate, and polybutyl methacrylate are preferably used.
The acrylic beads may be obtained by polymerizing the above monomers alone, or may be obtained by mixing and polymerizing two or more monomers.
In addition, acrylic beads are used by mixing with one or more polymer beads made of synthetic resin such as polystyrene, polyamide, polyethylene, polypropylene, polyurethane, polyester resin, acrylonitrile resin, fluororesin, silicone resin, polyvinyl chloride. Also good.

In the second aspect of the present invention uses a E PDM as rubber component.
The friction coefficient of EPDM can be easily adjusted depending on the amount of EPDM. In addition, since the main chain of EPDM is composed of saturated hydrocarbons and does not contain double bonds, molecular cleavage is unlikely to occur even when exposed to an environment such as high-concentration ozone atmosphere and light irradiation for a long time. Therefore, EPDM is the main component from the viewpoint of enhancing the weather resistance and oxidation resistance of the paper sheet multi-feed preventing member .
EPDM includes a non-oil-extended EPDM composed of only a rubber component and an oil-extended EPDM containing a confidential oil together with a rubber component. Any type of EPDM can be used in the present invention. When oil-extended EPDM is used, it is preferable that the rubber component and / or the elastomer component excluding the extending oil are within the above-described range.

The EPDM rubber, the rubber particles dynamically crosslinked by a resin crosslinking agent is dispersed in the polypropylene.
With this configuration, the EPDM rubber component becomes a so-called dynamic cross-linkable thermoplastic elastomer.
According to the dynamic crosslinking, the rubber component and the thermoplastic polymer can be effectively alloyed, and the islands of the rubber particles can be dispersed in the matrix made of the thermoplastic polymer. According to such a composition, it is possible to achieve both the advantages of the thermoplastic polymer and the excellent physical properties of rubber. Therefore, the wear resistance of the paper sheet multi-feed preventing member can be further improved, and the effect of preventing squealing can be enhanced.

In addition, by assuming that the dynamically cross-linked rubber particles are dispersed in the thermoplastic polymer, the formed multifeed prevention member can omit the surface polishing step or shorten the polishing time in the surface polishing step. An appropriate friction coefficient can be set.
The double feed prevention member is hard to wear when the thermoplastic polymer is blended, but even if the surface is worn by long-term use, the state in which the rubber particles are dispersed in the thermoplastic polymer matrix from the inside Therefore, it is possible to always maintain a substantially constant surface roughness, and as a result, it is possible to suppress the change with time of the friction coefficient.

As described above , EPDM is used as the rubber component for the rubber particles.
As rubber components other than EPDM, butyl rubber (IIR), butadiene rubber (BR), isoprene rubber (IR), styrene butadiene rubber (SBR), chloroprene rubber (CR), natural rubber (NR), 1,2- One or more selected from polybutadiene, acrylonitrile-butadiene rubber (NBR), ethylene propylene rubber (EPR), acrylic rubber (ACM, ANM), epichlorohydrin rubber (ECO) and the like may be used in combination.

  The rubber particles having a smaller particle diameter are preferable because they are uniformly dispersed in the matrix. Specifically, the average particle diameter of the rubber particles is preferably 10 μm or less, and particularly preferably 5 μm or less. Although the average particle diameter is preferably as small as possible, the average particle diameter of rubber particles usually obtained is 0.1 μm or more.

The dynamic crosslinking is preferably performed using a resin crosslinking agent.
By using a resin cross-linking agent, blooming that tends to occur when sulfur and a vulcanization accelerator are used is suppressed, and a reduction in the friction coefficient of the multifeed preventing member caused by blooming is prevented.
Preferable resin cross-linking agents include alkylphenol-formaldehyde resins obtained by reaction of alkylphenol having an alkyl group bonded to the ortho or para position of benzene with formaldehyde. Moreover, the halide of this alkylphenol formaldehyde resin is also used suitably. These resin cross-linking agents are preferable because they are excellent in compatibility with rubber, and are rich in reactivity so that the time for starting the cross-linking reaction is shortened.
Specific product names of the resin crosslinking agent include alkylphenol resins or brominated alkylphenols such as tackol 201, tackol 250-III (manufactured by Taoka Chemical Co., Ltd.), and hitanol 2501 (manufactured by Hitachi Chemical Co., Ltd.). Examples include formaldehyde resin.

  The lower limit of the compounding amount of the resin crosslinking agent is preferably 1 part by weight, more preferably 3 parts by weight, with respect to 100 parts by weight of the rubber component and / or elastomer component. Is particularly preferred. This is because if the blending amount is less than the above range, insufficient crosslinking occurs, and the durability of the multifeed preventing member may be lowered. Furthermore, the upper limit value is preferably 20 parts by mass, more preferably 15 parts by mass, and particularly preferably 10 parts by mass or less. If the blending amount exceeds the above range, the rubber and / or elastomer composition may be thermally deteriorated due to excessive heat generation due to abnormal heat generation during dynamic crosslinking.

When the polypropylene is used as the matrix resin in which the rubber particles are dispersed, the multifeed prevention member after the end of the use period is heated and melted, so that it can be used as a recycled polymer material, contributing to resource saving. sell. Further, since the need for disposal or incineration of the multifeed prevention member is eliminated by reuse, this multifeed prevention member has the advantage of not adversely affecting the global environment.

Since polypropylene of the thermoplastic polymer wherein the rubber particles are matrix to disperse the molecular chain is in a saturated state, without resulting in crosslinked during dynamic crosslinking, heavy because availability easily at low cost to one general This is because it is possible to reduce the cost of manufacturing feed preventing member.

Polypropylene of the thermoplastic polymer is less expensive and has good moldability, abrasion resistance is improved in the case of using as a component of multi-feed preventing member. In particular, if polypropylene having a melt flow rate of 0.5 or more and 10 or less (particularly 0.5 or more and 5.0 or less) is used, the wear resistance of the multifeed prevention member is further improved. The melt flow rate is measured according to JIS-K-6758.
Even when polypropylene is used in combination with other thermoplastic polymers, it is preferable that polypropylene is the main component. Specifically, the proportion of polypropylene in the total thermoplastic polymer is preferably 50% by mass or more, particularly 75% by mass or more. The higher the proportion of polypropylene, the better. Therefore, the upper limit is not particularly defined. That is, ideally, all the thermoplastic polymers except the acrylic beads, which are essential components, are polypropylene (especially polypropylene having a melt flow rate of 0.5 or more and 5.0 or less).
For the above-described reason, the second invention of the present invention uses a polyolefin-based thermoplastic elastomer in which rubber particles made of EPDM dynamically crosslinked with a resin crosslinking agent are dispersed in a thermoplastic polymer made of polypropylene.

Mass ratio of the polypropylene of the thermoplastic polymer and rubber component before Symbol EPDM rubber particles (polypropylene EPDM rubber rubber component / thermoplastic polymer particles) is set to 5 50/50 or 7 5/25 or less. When mass ratio exceeds 50/50, there is the friction coefficient of the multi-feed prevention member is reduced. On the other hand, when the mass ratio is less than 75/25 , the thermoplastic polymer may not be a matrix, and it may be difficult to plasticize the polymer composition.

In the first invention, Ru Tei using Po Riesuteru based thermoplastic elastomer. It is particularly preferable that all of the rubber component and / or the elastomer component be a polyester-based thermoplastic elastomer, because it is possible to achieve a balance between preventing paper sheets from being double fed, preventing squealing, and improving wear resistance. . The polyester-based thermoplastic elastomer can also be used by mixing with one or more of the above-described rubber component and / or elastomer component. In this case, the polyester-based thermoplastic elastomer is a rubber component or / and an elastomer component. It is preferable that it is 60 mass% or more in it.

The polyester-based thermoplastic elastomer can be easily adjusted in hardness by adjusting the blending amount or the ratio between the hard segment and the soft segment, and can have a restitution coefficient of a required height. As described above, the polyester-based thermoplastic elastomer has a moderately high restitution coefficient and a low loss coefficient (tan δ), and has a squeal prevention function and a hardness suitable for paper passing.
That is, if the hardness is too high, the wear resistance is good, but the friction coefficient is low and double feed is likely to occur, but since the hardness is moderately high, the occurrence of squeal is prevented while preventing double feed. it can. Furthermore, it is excellent in tensile strength and elongation, and wear resistance is also improved. As described above, the three requirements of prevention of double feeding, prevention of squealing, and improvement of wear resistance can be achieved in a balanced manner.

When the polyester-based thermoplastic elastomer is used as a main component of the rubber component or / and the elastomer component, the JIS A hardness in a state where no acrylic beads are contained is preferably 75 to 85.
Since the polyester-based thermoplastic elastomer has a low tan δ, the coefficient of restitution is high. When tan δ is lower, the double feed prevention member is less likely to stick and slip, and noise is less likely to occur.
Further, the polyester-based thermoplastic elastomer is excellent in low temperature characteristics, and is excellent in oil resistance and heat resistance. Therefore, the paper sheet multi-feed preventing member containing the polyester-based thermoplastic elastomer maintains a high friction coefficient even at a low temperature, can reliably prevent the paper sheets from being multi-fed, and has excellent durability.

The polyester-based thermoplastic elastomer comprises a hard segment (crystalline phase) and a soft segment (amorphous phase), the hard segment comprises an aromatic dicarboxylic acid diester group, and the soft segment comprises an aromatic carboxylic acid ester or It preferably consists of an aliphatic polyether group.
The hard segment generally consists of an aromatic dicarboxylic acid diester group.
Examples of the raw material aromatic dicarboxylic acid constituting the hard segment include phthalic acid such as terephthalic acid and isophthalic acid, and 2,6-naphthalenedicarboxylic acid. Of these, terephthalic acid is particularly preferable. As an alcohol that forms an ester with an aromatic dicarboxylic acid, an aliphatic diol represented by the general formula HO (CH ₂ ) nOH (n is an integer of 2 to 12, preferably 2 to 6), 1, Alicyclic diols such as 1-cyclohexanedimethanol and 1,4-cyclohexanedimethanol are preferred. Specific examples of the hard segment include, for example, a polybutylene terephthalate group: {CO—C ₆ H ₄ —COO (CH ₂ ) ₄
-O}.

The soft segment includes, for example, an aromatic carboxylic acid ester group, an aliphatic carboxylic acid ester group, an aliphatic polyether group, and the like. Examples of the raw material aromatic carboxylic acid constituting the soft segment include aromatic hydroxycarboxylic acids each having a carboxyl group and a hydroxyl group at both ends. The raw material aliphatic polyether constituting the soft segment is preferably polyalkylene ether glycol. The weight average molecular weight of the polyalkylene ether glycol is generally 400 to 6000. The soft segment made of an aliphatic polyether group may further contain an ester group. As the carboxylic acid that forms an ester with the aliphatic polyether, phthalic acid or the like is preferable. Specific examples of the soft segment, for example, _{[CO-C 6 H 4 -COO} - {(CH 2) 4 O} 5 -], include _{(CO-CH 2 CH 2 CH} 2 CH 2 CH 2 O) m , etc. .

  In the polyester-based thermoplastic elastomer, a hard segment and a soft segment constitute a block copolymer. The molar ratio of the hard segment to the soft segment in the block copolymer is generally 15 to 90% for the former and 85 to 10% for the latter.

The rubber component or / and the elastomer component may include a rubber made of EPDM or the like as described above together with the polyester-based thermoplastic elastomer and may be dynamically crosslinked.
According to the dynamic cross-linking, the rubber component and the polyester thermoplastic elastomer can be effectively alloyed, and the islands of the rubber particles can be dispersed in the matrix made of the polyester thermoplastic elastomer. According to such a composition, it is possible to achieve both the advantages of the polyester-based thermoplastic elastomer and the excellent physical properties of rubber. Therefore, the wear resistance of the paper sheet multi-feed preventing member can be further improved, and the effect of preventing squealing can be enhanced.

In the composition for molding the paper sheet multi-feed preventing member of the present invention, a softener, a crosslinking activator, and a filler for improving strength may be mixed together with the rubber component and / or elastomer component and acrylic beads. Good.
Examples of the softener include oils and plasticizers. As the oil, paraffinic, naphthenic, aromatic, or other mineral oils or hydrocarbon-based oligomers known per se, or process oils should be used. Can do. As the synthetic oil, for example, an oligomer with α-olefin, an oligomer of butene, and an amorphous oligomer of ethylene and α-olefin are preferable. As the plasticizer, for example, dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl separate (DOS), dioctyl adipate (DOA) and the like can be used.

  In addition, a crosslinking activator may be used in order to appropriately perform the crosslinking reaction. As the crosslinking activator, for example, a metal oxide is preferably used, and zinc oxide and zinc carbonate are particularly preferable. The blending amount is suitably from 1 part by mass to 5 parts by mass with respect to 100 parts by mass of the rubber component and / or elastomer component (excluding the softening agent) for reasons of processability.

Furthermore, an appropriate amount of a filler, a reinforcing agent, an anti-aging agent, a wax, a colorant, a crosslinking aid, etc. may be added as necessary.
Examples of the filler include talc, silica, carbon, titanium oxide, aluminum, whisker, calcium carbonate, clay, glass fiber, and carbon fiber. By adding the filler, the mechanical strength of the paper sheet multi-feed preventing member can be improved. The blending amount of the filler is preferably 30 parts by mass or less with respect to 100 parts by mass of the rubber component and / or the elastomer component. This is because if the ratio of the filler exceeds the above range, the flexibility of the rubber may be lowered.

  Carbon black or the like is used as the reinforcing agent. By adding carbon black, it is possible to improve the wear resistance of the multifeed preventing member. As the carbon black, for example, carbon black such as HAF, MAF, FEF, GPF, SRF, SAF, MT, and FT can be used. From the viewpoint of dispersibility in the composition, the particle size of carbon black is preferably 10 nm or more and 100 nm or less. The blending amount of carbon black is preferably, for example, from 0.1 parts by weight to 30 parts by weight with respect to 100 parts by weight of the rubber component and / or the elastomer component.

  Examples of the anti-aging agent include imidazoles such as 2-mercaptobenzimidazole, phenyl-α-naphthylamine, N, N′-di-6-naphthyl-p-phenylenediamine, N-phenyl-N′-isopropyl- Examples thereof include amines such as p-phenylenediamine.

Preparation of the composition containing the rubber component or / and elastomer component, acrylic beads and the like can be performed by a conventional method conventionally performed.
For example, the composition can be obtained by kneading a predetermined compound using a known kneading apparatus such as an open roll, a Banbury mixer, a kneader, a single screw extruder, a twin screw extruder or the like. The temperature of the compound during kneading is, for example, 160 ° C to 220 ° C. The obtained composition is molded into a required shape by known molding means such as extrusion molding, injection molding, and compression molding.

  As described above, according to the paper sheet multi-feed preventing member of the present invention, the surface of OHP paper, resin-coated paper, etc. is made of synthetic resin by adding acrylic beads to the rubber component and / or elastomer component. Adherence between the leaves and the surface of the multifeed prevention member can be prevented. As a result, while the friction coefficient with respect to plain paper is within an appropriate range, the friction coefficient with respect to paper sheets such as OHP paper can also be within an appropriate range. Can be prevented.

Further, by containing acrylic beads, the multifeed preventing member itself is not easily worn even during long-term use, can provide an appropriate friction coefficient over a long period of time, and has excellent wear resistance.
Therefore, in paper feeding mechanisms such as inkjet printers, laser printers, electrostatic copying machines, plain paper facsimile machines, etc., when placed facing the paper feed roller, the paper sheet separation performance can be stabilized and durable. Since it is excellent in wear resistance, it can be used well.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing a paper feed mechanism using a separation pad 23 as a paper sheet multi-feed preventing member. In the paper feeding mechanism, the tray 21 and the paper feeding roller 12 are spaced apart from each other, and a separation pad 23 fixed to the substrate 22 is provided at a position facing the paper feeding roller 12. The separation pad 23 serves as a paper sheet multi-feed preventing member.
As the sheet feeding roller 12 rotates in the direction indicated by the arrow R in the figure, the sheets 15 on the tray 21 are sent out one by one toward the image forming mechanism.

A first embodiment of the paper sheet multi-feed preventing member of the present invention comprising the separation pad 23 will be described in detail below.
The separation pad 23 of the first embodiment is made of acrylic beads on an elastomer in which rubber particles made of EPDM are dynamically crosslinked by a resin crosslinking agent and dispersed in a thermoplastic polymer made of polypropylene as a rubber component or / and an elastomer component. Is molded from a blended composition. Therefore, acrylic beads are dispersed in the molded separation pad 23, and a part thereof is exposed on the surface of the separation pad 23. The exposed acrylic beads particles directly rub against the paper sheet 11 so that the surface of the OHP film, resin-coated paper, etc. made of synthetic resin can be prevented from sticking to the surface of the separation pad 23. I have to.

The blending amount of the acrylic beads with respect to the entire composition is 10% by mass or less, but in the present embodiment, it is 1 to 4% by mass.
As the acrylic beads, spherical acrylic beads having an average particle diameter of 4 to 100 μm mainly composed of polymethacrylate-based polymers such as polymethyl methacrylate, polyethyl methacrylate, and polybutyl methacrylate are used.

As described above, EPDM is used for the rubber particles because of excellent weather resistance and oxidation resistance, but other rubber may be used in combination with EPDM.
EPDM includes non-oil-extended EPDM composed only of a rubber component and oil-extended EPDM including a confidential oil together with a rubber component, and any of them may be used. 50% oil-extended EPDM is used.

A resin cross-linking agent for cross-linking EPDM is blended into the matrix elastomer. Examples of the resin cross-linking agent include alkylphenol-formaldehyde resins and alkylphenol-formaldehyde resin halides. In the present embodiment, reactive alkylphenol resins are used. The resin cross-linking agent is excellent in compatibility with rubber, has high reactivity, can shorten the time for starting the cross-linking reaction, and can suppress blooming after molding.
In this embodiment, the compounding amount of the resin crosslinking agent is 5 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the elastomer.

  As described above, polypropylene (especially polypropylene having a melt flow rate of 0.5 or more and 5.0 or less) is used as the thermoplastic polymer as the matrix. Polypropylene is suitable because it is inexpensive and easy to mold, and wear resistance is improved. Even when polypropylene is used in combination with other thermoplastic polymers, it is preferable that polypropylene is the main component.

The mass ratio of EPDM to polypropylene (EPDM / polypropylene) in the elastomer is 50/50 or more and 75/25 or less. By setting it as this range, a polypropylene exists as a matrix without making the friction coefficient of a separation pad too small, and has thermoplasticity as a composition.
Along with the elastomer and acrylic beads, an appropriate amount of a softening agent, a filler, a reinforcing agent, an anti-aging agent, a wax, a coloring agent, a crosslinking aid, etc. may be added to the composition as necessary.

The composition for forming the separation pad 23 is composed of rubber components (EPDM) of rubber particles, acrylic beads, thermoplastic polymer (polypropylene), resin cross-linking agents, various additives, etc., open roll, Banbury mixer, kneader, single screw extrusion. It is prepared by kneading with a known kneader such as a machine or a twin screw extruder.
During kneading, the rubber particles are crosslinked to form fine rubber particles, which are dispersed in a thermoplastic polymer matrix to form a so-called dynamically crosslinked thermoplastic elastomer. The obtained composition is molded into a sheet having a required shape by known molding means such as extrusion molding, injection molding, and compression molding. The sheet is sliced to a desired thickness and then cut into a rectangle having a desired size to form a separation pad 23 which is a multi-feed preventing member for paper sheets.
The kneading machine is preferably a twin screw extruder because the thermoplastic polymer can be used as a matrix even when the blending amount of the rubber is slightly higher than the blending amount of the thermoplastic polymer. The acrylic beads may be added after other compounding agents are kneaded and further kneaded.

Next, the separation pad 23 which is a paper sheet multi-feed preventing member of the second embodiment will be described.
The separation pad 23 of the second embodiment uses a polyester thermoplastic elastomer alone as a rubber component or / and an elastomer component, and blends acrylic beads at a ratio of 0.5 to 9% by mass with respect to the entire composition. ing.

In the polyester-based thermoplastic elastomer, the hard segment is composed of an aromatic dicarboxylic acid diester group, and the soft segment is composed of an aromatic carboxylic acid ester or an aliphatic polyether group.
Polybutylene terephthalate group made of a combination of dimethyl terephthalate as the raw material aromatic dicarboxylic acid constituting the hard segment and butanediol as the alcohol forming ester with the aromatic dicarboxylic acid: {CO-C ₆ H ₄ —COO (CH ₂ ) ₄
-O} is used.

The soft segment is composed of an aromatic hydroxycarboxylic acid having a carboxyl group and a hydroxyl group at both ends. As the raw material aliphatic polyether constituting the soft segment, polytetramethylene ether glycol (PTMG), poly (1,2-propylene oxide) glycol, poly (ethylene oxide) glycol or the like is used. As the carboxylic acid that forms an ester with the aliphatic polyether, terephthalic acid or the like is preferable. As a specific example of the soft segment, for example, [CO-C ₆ H ₄
—COO — {(CH ₂ ) ₄ O} ₅ —] (CO—CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ O) m
Etc.

  In the polyester-based thermoplastic elastomer, a hard segment and a soft segment constitute a block copolymer. The molar ratio of the hard segment to the soft segment in the block copolymer is generally 15 to 90% for the former and 85 to 10% for the latter.

As with the first embodiment, acrylic beads are blended with the polyester-based thermoplastic elastomer. Moreover, you may mix | blend an appropriate amount of another filler as needed. Examples of the filler include carbon black, silicon oxide, and clay. In the present embodiment, carbon black is blended. The compounding amount of carbon black is 0.5 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the rubber component and / or the elastomer component.
Furthermore, you may mix | blend an appropriate quantity with softeners, such as oil and a plasticizer, anti-aging agent, a coloring agent, and a reinforcing fiber as needed.

As described above, in the second embodiment, since the separation pad 23 is formed of a composition containing a polyester-based thermoplastic elastomer as an elastomer component, it is easy to adjust the hardness, and the hardness of the paper sheet multi-feed preventing member is In consideration of the relationship between the friction coefficient and the wear resistance, it can be designed to have an appropriate hardness.
The polyester-based thermoplastic elastomer is excellent in low temperature characteristics, maintains a high coefficient of friction even at low temperatures, can reliably prevent double feeding of paper sheets, and has excellent durability. Excellent oil resistance and heat resistance.

  As a paper sheet multi-feed preventing member, there is also a paper feeding mechanism provided with a separation roller in place of the separation pad 23 shown in FIG. 1, and a paper feeding mechanism provided with both the separation pad 23 and a separation sheet. Is also present. In any case, these paper sheet multi-feed preventing members (separation pad, separation roller, separation sheet, etc.) can be formed from the composition described in the first embodiment or the second embodiment.

Hereinafter, examples and comparative examples of the paper sheet multi-feed preventing member of the present invention will be described in detail.
Needless to say, the present invention should not be construed in a limited manner based on the description of the examples.
As shown in Table 1 below, kneaded materials having the formulations shown in Table 1 were prepared for Examples and Comparative Examples.

The numerical unit of each composition of each component in Table 1 is part by mass, and those indicated in parentheses for acrylic beads and cork particles are the mass% of acrylic beads and cork particles in the rubber or / and elastomer composition. is there.
Details of the materials used are as follows.
EPDM: “Esprene 670F (trade name)” manufactured by Sumitomo Chemical Co., Ltd. (oil weight 50% by mass, rubber component 50% by mass)
Polypropylene: “NOVATEC MG05BS (trade name)” manufactured by Nippon Polychem Co., Ltd.
Polyester thermoplastic elastomer: “Hytrel 3046 (trade name)” manufactured by Toray DuPont Co., Ltd., including [CO—C ₆ H ₄ —COO (CH ₂ ) ₄ —O—] x as a hard segment, as a soft segment _{[CO-C 6 H 4 -COO} {(CH 2) POq}] is intended to include n.
Acrylic beads: “Gantz Pearl GBX-10S (trade name)” manufactured by Ganz Kasei Co., Ltd. (cosmetic grade, average particle size 4 to 100 μm)
Carbon: “Seast SO (trade name)” manufactured by Tokai Carbon Co., Ltd.
Resin cross-linking agent: “Tacchi Roll 250-III (trade name)” manufactured by Taoka Chemical Co., Ltd.

(Example 1 to Example 3)
After blending EPDM (ethylene-propylene-diene rubber), polypropylene, resin cross-linking agent, and acrylic beads with the composition shown in Table 1, dry blending using a tumbler, the mixture was put into a twin screw extruder, kneaded at 200 ° C, and simultaneously Dynamic crosslinking was performed and extruded into a sheet. The obtained sheet was sliced or polished to obtain a sheet-like paper sheet multi-feed preventing member having a thickness of 2.0 mm.
(Comparative Example 1)
A paper sheet multi-feed preventing member was produced in the same manner as in Examples 1 to 3 except that no acrylic beads were blended.
(Comparative Example 2)
A paper sheet multi-feed preventing member was produced in the same manner as in Examples 1 to 3 except that cork particles were blended in place of the acrylic beads.

Example 4
A paper sheet multi-feed preventing member was prepared in the same manner as in Examples 1 to 3 except that the composition of the composition was changed as shown in Table 1.
(Comparative Example 3)
A paper sheet multi-feed preventing member was produced in the same manner as in Example 4 except that the acrylic beads were not blended.

  The initial friction coefficient, squeal occurrence state, paper passing state, and wear amount of the paper sheet multi-feed preventing members of Examples 1 to 4 and Comparative Examples 1 to 3 were tested and evaluated as follows. .

(Measurement of initial friction coefficient)
A Haydon 14 type friction coefficient measuring machine (“Tribogear” manufactured by Shinto Kagaku Co., Ltd., TYPE: HEIDON-14DR) was used. Properbond paper (trade name) manufactured by Canon Co., Ltd. was used as the measurement paper, and OHP sheets for color laser printers manufactured by Epson Co., Ltd. were used as the measurement paper. Load 1.96 N, speed 600 mm / min. Measured under conditions.

(Status of squeal occurrence)
The paper sheet multi-feed preventing member of each example and comparative example is mounted on a printer (trade name “LBP1310 (trade name)” manufactured by Canon Inc.), and 200 sheets of OHP paper at 23 ° C. and 55% relative humidity. The presence or absence of abnormal noise (squeal) when passing through the paper was observed. The case where no squeal occurred was defined as “None”, and the case where even a slight squeal occurred was defined as “Yes”.

(Paper delivery status)
The paper sheet multi-feed prevention member of each example and comparative example is mounted on a printer (trade name “LBP1310 (trade name)” manufactured by Canon Inc.), 30000 plain paper at 23 ° C. and 55% relative humidity. The state of passing paper was observed while passing through the sheets. The case where no double feeding occurred was defined as “good”, and the case where polymerization occurred several times was regarded as “double feeding occurred”.

(Abrasion amount)
The amount of wear was expressed in units of mg by measuring the mass difference of the multifeed preventing member before and after the paper passing test. The smaller the value, the better the wear resistance of the sample.

Compared with Example 1 to Example 3, the double feed prevention member of Comparative Example 1 using a composition having the same composition except that acrylic beads are not blended has a large initial friction coefficient of OHP of 1.7. Further, the occurrence of squeal was confirmed, which was inferior to the double feed prevention member of the example.
In Comparative Example 2 in which 30% by mass of cork particles were blended instead of acrylic beads, the initial friction coefficient was good for both plain paper and OHP paper as compared with Examples 1 to 3, but double feed Generation | occurrence | production was confirmed and it was inferior compared with the double feed prevention member of an Example.

  Compared to Example 4, the double feed prevention member of Comparative Example 3 using the same composition except that acrylic beads were not blended had a large initial friction coefficient of OHP paper of 1.8 and Occurrence was also confirmed. Furthermore, the amount of wear was as large as 14.3 mg, which was inferior to the double feed prevention member of Example 4.

In each of the multifeed prevention rubber members of Examples 1 to 4, the initial friction coefficient for plain paper is an appropriate value of 0.7 to 1.0, and the initial friction coefficient for OHP paper is also 1.0 to 1.3. And the value was appropriate. The paper passing performance was also good, and no “squeal” was confirmed. Further, the wear amount of Example 4 was 6.2 mg, which was smaller than that of the double feed preventing member of Comparative Example 3, and was excellent in wear resistance.
Therefore, the multifeed prevention member containing the acrylic beads of Examples 1 to 4 is an excellent multifeed prevention member, and in particular, when the paper sheet is made of a resin such as OHP paper and has high smoothness. In addition, it was confirmed that it has excellent wear resistance and can be used widely and widely in various papers. Further, since it is not sulfur vulcanization, it is a high-performance multifeed prevention member that has no problem of bloom and is excellent in durability such as oxidation resistance.

FIG. 5 is a schematic cross-sectional view showing a paper feed mechanism using a separation pad as a multi-feed preventing member for paper sheets of the present invention. It is explanatory drawing of the conventional paper feed double feed prevention member.

Explanation of symbols

12 Paper feed roller 21 Tray 15 Paper sheet 22 Substrate 23 Separation pad

Claims (2)

Weight of paper sheets comprising a polyester-based thermoplastic elastomer and 0.5-9 parts by mass of acrylic beads , the acrylic beads being dispersed in the polyester-based thermoplastic elastomer, and a sheet-like separation pad exposed on the surface Anti-feed member. EPDM rubber and polypropylene are blended such that (EPDM / polypropylene) is 50/50 or more and 75/25 or less, and acrylic beads are blended at 1 to 4% by mass of the total composition, and EPDM rubber and polypropylene are blended in the polypropylene. A paper sheet multi-feed prevention member comprising a sheet-like separation pad in which acrylic beads are dispersed and exposed on the surface .

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