JP5111832B2 - Paper feed roller - Google Patents

Description

  The present invention relates to a paper feed roller used for a paper feed mechanism in a copying machine, a printer, a facsimile machine, an automatic deposit payment machine (ATM), and the like, and more specifically, an annular elastic body (rubber roll) mounted on an outer peripheral surface of a core body. Is a two-layer structure consisting of an inner layer and an outer layer, which suppresses a decrease in the coefficient of friction and the occurrence of a squeal phenomenon.

Various paper feed rollers are used in a paper feed mechanism such as an electrostatic copying machine, various printers, a plain paper facsimile apparatus, and an automatic deposit payment machine (ATM). The paper feed roller is a roller that contacts paper (including thin leaf bodies other than paper; the same applies hereinafter) and that transports the paper by rotation and friction on the roll surface, and includes a paper feed roller, a registration roller, It refers to a conveyance roller, a transfer roller, and the like.
Conventionally, natural rubber, urethane rubber, ethylene-propylene-diene rubber (EPDM rubber), polynorbornene rubber, silicone rubber, chlorinated polyethylene rubber, and the like are used as the material for the rubber roll of the paper feed roller.

  Conventionally, many rubber rolls used as this type of paper feed roller have a single-layer structure composed of a non-foamed layer. However, in the case of a single-layer structure, the friction coefficient tends to decrease as the number of sheets passed increases. If the coefficient of friction decreases, the ability to feed the paper is reduced, so that conveyance failure occurs or a squealing phenomenon occurs due to the paper sliding on the roll surface. Therefore, in recent years, it has been proposed to improve the wear resistance and suppress the reduction of the friction coefficient by adopting a two-layer structure or a three-layer structure.

For example, Japanese Patent Application Laid-Open No. 2001-341862 (Patent Document 1) discloses a two-layer feed roller composed of an inner layer of a foam layer and an outer layer of a non-foam layer, an innermost layer of a non-foam layer, and an inner layer of a foam layer. And a paper feeding roller having a three-layer structure comprising a non-foamed outer layer.
In Patent Document 1, from the viewpoint of obtaining a sufficient nip amount, the ASKA-C hardness of the foamed layer is preferably controlled to 50 degrees or less, and the JIS-A hardness of the non-foamed layer is preferably controlled to 60 degrees or less. Yes. The innermost layer in the three-layer paper feed roller is for strengthening the fixation of the rubber roll to the core.

  Japanese Patent Laid-Open No. 2002-347972 (Patent Document 2) discloses a two-layer rubber roll having an upper layer and a lower layer in which JIS-A hardness is controlled within a certain range. Here, the upper layer JIS-A hardness is controlled to 35 degrees to 50 degrees, and the lower layer JIS-A hardness is controlled to 25 degrees or less from the viewpoint of achieving both improvement in wear resistance of the upper layer and reduction in conveyance failure and squealing phenomenon. Has been.

  When the outer layer has a high rubber hardness and the inner layer has a low rubber hardness as in Patent Documents 1 and 2, a certain effect is obtained for improving the wear resistance of the outer layer and reducing conveyance failure and squealing phenomenon. However, there is a problem in that no consideration is given to preventing mass transfer and bleeding between the inner layer and the outer layer, and the effect is not sufficient.

In order to solve the above problems, the present applicant has developed a three-layer rubber roll in which a non-foamed intermediate layer is sandwiched between a non-foamed inner layer and an outer layer whose JIS-A hardness is controlled within a certain range. (Japanese Patent Laid-Open No. 2006-111401 (Patent Document 3)).
Thus, by providing an intermediate layer between the inner layer and the outer layer, mass transfer and bleeding between the inner layer and the outer layer can be prevented.

JP 2001-341862 A JP 2002-347972 A JP 2006-111401 A

  The present invention has been made in view of the above problems, and has a high coefficient of friction and wear resistance, and the decrease in the coefficient of friction is small even when the number of sheets to be passed increases. It is an object of the present invention to provide a paper feed roller having a simpler structure that can be reduced to a high level and can suppress mass transfer between the inner layer and the outer layer and maintain excellent performance over a long period of time.

In order to solve the above problems, the present invention provides:
It has two rubber layers, an inner layer and an outer layer, and the outer peripheral surface of the inner layer and the inner peripheral surface of the outer layer are in close contact with each other without a gap,
While the inner layer contains silicone rubber as a rubber component, the inner layer has a JIS-A hardness of 10 degrees or less and a thickness of 2 mm to 10 mm ,
The outer layer contains only EPDM rubber and / or urethane rubber as a rubber component, the hardness of the outer layer is 25 degrees or more and 30 degrees or less , and the thickness is 1 mm or more and 8 mm or less ,
A paper feed roller is provided in which the inner layer and the outer layer are non-foamed layers.

In the examples of Patent Documents 1 to 3, EPDM rubber is used as the rubber component of the inner layer, but it is possible to make the JIS-A hardness 10 degrees or less using EPDM rubber. However, in order to reduce the JIS-A hardness to 10 degrees or less, it is necessary to add a large amount of a softening agent, so that the softening agent is transferred to the outer layer and bleeding occurs. If no countermeasures are taken against such mass transfer and bleed between the inner layer and the outer layer as in Patent Documents 1 and 2, the effects of the invention of improving the wear resistance of the outer layer and reducing the conveyance failure and squealing phenomenon are attenuated. Is done. Therefore, in the invention described in Patent Document 3, it is necessary to provide an intermediate layer between the inner layer and the outer layer in order to eliminate mass transfer and bleeding between the inner layer and the outer layer.
On the other hand, in the present invention, it is difficult to cause the transition of the softening agent and bleed by reducing the amount of the softening agent contained in the inner layer instead of blocking the transition and bleeding of the softening agent by changing the way of thinking. Considered to do. As a result, it has been found that by using silicone rubber as the rubber component of the inner layer, the JIS-A hardness can be reduced to 10 degrees or less without adding a large amount of softener. Thus, there is an advantage that it is not necessary to provide an intermediate layer that is essential in the invention described in Patent Document 3, and a paper feed roll having a simpler structure can be provided.

In the present invention, the paper feed roller is composed of two rubber layers, the inner layer and the outer layer, and the inner layer and the outer layer are adhered to each other without causing a gap between the outer surface and the inner layer of the outer layer. The hardness of the roller can be set to a predetermined hardness without variation throughout. As a result, it is possible to prevent uneven wear of the roller and to suppress occurrence of outer diameter flare of the roller.
In particular, in the paper feed roller of the present invention, it is preferable that the outer layer is integrated and fitted to the outer peripheral surface of the inner layer without an adhesive. By adopting such a structure that does not use an adhesive, only the outer layer can be exchanged when the outer layer deteriorates due to direct contact with the outside air or paper and reaches the end of its life.

The inner layer preferably has a JIS-A hardness of 5 degrees or more, and the outer layer has a JIS-A hardness of 30 degrees or less.
In the present invention, by setting the JIS-A hardness of the inner layer as low as 10 degrees or less, a sufficient contact area between the roller and the paper can be secured, and a decrease in the friction coefficient of the roller can be suppressed. At the same time, the occurrence of squealing phenomenon can be reduced. When the JIS-A hardness of the inner layer is higher than 10 degrees, it is difficult to ensure a sufficient contact area between the paper feed roller and the paper over a long period of time, and it is difficult to suppress a decrease in the friction coefficient.
The lower limit of the JIS-A hardness of the inner layer is not limited, and includes a state where the hardness is too low and the needle does not move on the hardness meter and indicates “0”, but 5 degrees or more is preferable.

On the other hand, by setting the JIS-A hardness of the outer layer as high as 25 degrees or more and 30 degrees or less, it is possible to achieve a balance between the wear resistance and the friction coefficient. When the JIS-A hardness of the outer layer is less than 25 degrees, the wear resistance of the roller is lowered, and when it is more than 30 degrees, the friction coefficient is lowered and the performance as a roller may not be sufficiently exhibited.

The difference between the JIS-A hardness of the outer layer and the JIS-A hardness of the inner layer is 15 to 25 degrees from the viewpoint of sufficiently suppressing the decrease in the friction coefficient of the paper feed roller and the occurrence of the squeal phenomenon. desirable. If the difference in hardness is less than 15 degrees, the effect of suppressing squealing cannot be obtained, and if it exceeds 25 degrees, the hardness of the outer layer rubber increases and the friction coefficient decreases. The hardness difference is particularly preferably 20 to 25 degrees.

As described above, the rubber component of the inner layer of the present invention is silicone rubber.
Various silicone rubbers known per se can be used as the silicone rubber. Millable silicone rubber that can be handled in the same manner as the rubber material is preferably used. This millable silicone rubber is mainly composed of a linear polyorganosiloxane (silicone gum) having a high polymerization degree (6000 to 10000), and a silica-based reinforcing filler, a filler for weight increase, a dispersion accelerator, etc. It is supplied as a compounded rubber compound. As the above-mentioned silicone gum, methyl vinyl silicone [(CH ₂ ═CH) (CH ₃ ) SiO] is most commonly used, but in order to improve other physical properties of the rubber, for example, (CH ₃ ) ₂ SiO, (CF Polyorganaxane in which polymerized units such as ₃ CH ₂ CH ₂ ) ₂ SiO and (C ₆ H ₅ ) ₂ SiO are introduced into the straight chain is also used.

As the silicone rubber, a silicone rubber having high elongation and low stress is preferable so that the hardness of the inner layer is 10 degrees or less.
Specifically, the tensile stress at 50% elongation is preferably 0.2 MPa or less, or the tensile stress at 100% elongation is preferably 0.5 MPa or less. Moreover, it is preferable that elongation is 600% or more.
The tensile stress and elongation can be measured according to JIS K6249.

  The rubber component contained in the inner layer is preferably only silicone rubber, but other rubber components other than silicone rubber can be blended if necessary. The ratio of the “other rubber” in the total rubber component of the inner layer is preferably 10% by mass or less, and more preferably 5% by mass or less. Examples of the “other rubber component” include ethylene-propylene-diene rubber (EPDM), butadiene rubber (BR), isoprene rubber (IR), chloroprene rubber (CR), natural rubber (NR), acrylonitrile butadiene rubber (NBR), One or more rubber components selected from styrene butadiene rubber, styrene rubber (SBR), butyl rubber (IIR), and the like can be suitably used.

In the inner layer, additives such as a softening agent, a filler, a reinforcing agent, a coloring agent, or a deterioration preventing agent may be appropriately blended as necessary. For example, the hardness of the inner layer can be adjusted by selecting the type and blending amount of the softener or filler.
When a softening agent is blended, it is preferably contained in a proportion of 0 to 100 parts by mass with respect to 100 parts by mass of the rubber component. If the softening agent is contained in an amount exceeding 100 parts by mass with respect to 100 parts by mass of the rubber component, there is a risk of migration to the outer layer or bleeding, which improves the abrasion resistance of the outer layer, reduces conveyance failure and squealing phenomenon. This is because the effects of the invention may be reduced.

The rubber component of the outer layer of the present invention is made of EPDM rubber or urethane rubber which is different from the rubber component of the inner layer.
EPDM rubber is mostly composed of saturated hydrocarbons and contains few double bonds in the main chain, so molecular main chain cleavage is unlikely to occur even when exposed to high-concentration ozone atmosphere, light irradiation, or other environments for a long time. A paper feed roller having excellent ozone resistance can be obtained.
Urethane rubber is also excellent in ozone resistance and mechanical properties, and is effective in improving wear resistance.

The urethane rubber is a rubber made by reacting a polyol and an isocyanate, and is roughly classified into an ether type using a polyether polyol as a polyol and an ester type using a polyester polyol. In the present invention, any type may be used, but ester urethane rubber is preferably used.
Examples of the polyether polyol include polypropylene glycol (PPG) -based polyols, ethylene oxide-modified products or amine-modified products thereof, and polyoxytetramethylene glycol (PTMG).
Examples of the polyester polyol include a dicarboxylic acid such as adipic acid, isophthalic acid or terephthalic acid, and a polyol such as ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, 1,6-hexanediol, trimethylolpropane or neopentyl glycol. These condensation reaction products, polycaprolactone polyols, polycarbonate polyols and the like.
Examples of the isocyanate include aliphatic diisocyanates such as 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI) or lysine isocyanate; isophorone diisocyanate (IPDI), hydrogenated xylylene diisocyanate or hydrogenated 4, Alicyclic diisocyanates such as 4′-diphenylmethane diisocyanate; xylylene diisocyanate (XDI), tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), tolidine diisocyanate (TODI), p-phenylene diisocyanate or 1, Aromatic diisocyanates such as 5-naphthalene diisocyanate (NDI).

  Further, when urethane rubber is classified from the processed surface, an injection molding type, a millable type, a thermoplastic type and the like can be mentioned. Any type may be used in the present invention, but a millable type is preferably used. The millable type can be kneaded with rolls, Banbury mixers, kneaders, etc., as with normal rubber, and is cross-linked using a cross-linking agent such as sulfur or organic peroxide. A crosslinking compound having excellent wear resistance and compression set resistance can be provided.

The outer layer contains only EPDM rubber or urethane rubber as a rubber component .

  In the outer layer, additives such as a softening agent, a filler, a reinforcing agent, a colorant, or a deterioration preventing agent may be appropriately blended as necessary. For example, the hardness of the outer layer can be adjusted by selecting the type and blending amount of the softener or filler.

The paper feed roller of the present invention having the above-described configuration is characterized by a high coefficient of friction and wear resistance and a small decrease in the coefficient of friction even when the number of sheets passed is large.
As the index, the initial friction coefficient of the outer peripheral surface of the outer layer is preferably 1.5 or more. Especially, it is more preferable that the initial friction coefficient is 1.7 or more and 3.5 or less. Moreover, it is preferable that the friction coefficient after the paper passing test performed by the method as described in an Example below is 1.5 or more. Especially, it is more preferable that the friction coefficient after passing the paper is 1.6 or more and 3.0 or less. Further, the ratio of the post-paper friction coefficient to the initial friction coefficient is preferably 0.8 or more, and more preferably 0.9 or more.

According to the present invention, the paper feeding roller is composed of two rubber layers, the inner layer and the outer layer, and the inner layer and the outer layer are laminated by closely contacting the outer peripheral surface of the inner layer and the inner peripheral surface of the outer layer without a gap. The hardness can be made to be a predetermined hardness without variation throughout, and the wear resistance can be maintained.
In the paper feed roller of the present invention, the contact area between the roller and the paper can be sufficiently ensured by setting the JIS-A hardness of the inner layer to 10 degrees or less, so that a decrease in the friction coefficient of the roller can be suppressed. At the same time, it is possible to reduce the occurrence of the squeal phenomenon. By setting the JIS-A hardness of the outer layer to 25 to 30 degrees, it is possible to balance the wear resistance and the friction coefficient.

Since the rubber component of the inner layer is made of silicone rubber, low hardness can be realized even if the amount of softener is small, so the material transfer including the softener to the outer layer can be achieved without providing a barrier layer between the outer layer and the outer layer. It is possible to provide a paper feed roller that can suppress bleeding and bleed, has a simpler structure, and can maintain excellent performance over a long period of time.
Moreover, since the rubber component of the outer layer is made of EPDM rubber or urethane rubber, a paper feed roller having excellent wear resistance and ozone resistance can be obtained.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic perspective view showing a paper feed roller 10 according to the present invention together with a core body 11. The paper feed roller 10 is fixed to the core body 11 by press-fitting the core body 11 into the hollow portion of the paper feed roller 10.
The thickness of the paper feed roller 10 is not particularly limited, but is, for example, 1 mm or more and 20 mm or less. Further, the length of the paper feed roller 10 is not particularly limited, but is, for example, 3 mm or more and 200 mm or less.

The cross-sectional schematic diagram of FIG. 2 shows an example of a paper feed mechanism that uses the paper feed roller 10 of FIG. 1 as a paper feed roller. The paper feed mechanism includes a paper feed roller 10, a separation pad 12, and a tray 13. The separation pad 12 and the tray 13 are installed at a constant interval, and the upper surface of the separation pad 12 and the tray 13 form an elevation angle. The separation pad 12 is fixed to the substrate 14, and the separation pad 12 and the paper feed roller 10 face each other.
As the paper feed roller 10 rotates in the direction indicated by the arrow R in the figure, the paper 15 on the tray 13 in contact with the roller surface is sent out one by one.

  As shown in the cross-sectional view of FIG. 3, the paper feed roller 10 is composed of two layers, an inner rubber layer 16 and an outer rubber layer 17, and an outer peripheral surface of the inner rubber layer 16 and an inner rubber layer 17. It is in close contact with the peripheral surface without a gap. The structure is formed by fitting and integrating the outer layer 17 on the outer peripheral surface of the inner layer 16 without using an adhesive.

The inner rubber layer 16 is crosslinked and molded into a cylindrical shape, and its JIS-A hardness is adjusted to 10 degrees or less, preferably 5 degrees or more and 10 degrees or less.
The thickness of the inner layer 16 is 2 mm or more and 10 mm or less. If the thickness of the inner layer 16 is too small, the effect of suppressing squealing tends to decrease. On the other hand, when the thickness of the inner layer 16 is too large, uneven wear tends to occur.

The outer rubber layer 17 is crosslinked and molded into a cylindrical shape, and its JIS-A hardness is adjusted to 25 degrees or more and 30 degrees or less. Further, the difference between the JIS-A hardness of the outer layer 17 and the JIS-A hardness of the inner layer 16 is 15 degrees to 25 degrees, preferably 20 degrees, from the viewpoint of sufficiently suppressing the decrease in the friction coefficient of the roller and the occurrence of the squealing phenomenon. ~ 25 degrees.
The thickness of the outer rubber layer 17 is 1 mm or more and 8 mm or less. If the thickness of the outer layer 17 is too small, the life of the roller is shortened. On the other hand, if the thickness of the outer layer 17 is too large, the effect of softening the inner layer may be lost.

The inner rubber layer 16 contains silicone rubber alone as a rubber component.
As the silicone rubber, it is preferable to use a millable silicone rubber, and in particular, a silicone rubber having a high elongation and a low stress is used in order to make the inner layer have a hardness of 10 degrees or less. Specifically, the tensile stress at 100% elongation is preferably 0.1 to 0.5 MPa, and the elongation is preferably 700% or more.

The outer rubber layer 17 contains EPDM rubber as a rubber component.
EPDM rubber includes a non-oil-extended EPDM rubber composed only of a rubber component, and an oil-extended EPDM rubber containing an extended oil together with a rubber component of EPDM, and any type can be used.

The rubber components contained in the inner rubber layer 16 and the outer rubber layer 17 are cross-linked. The crosslinking form is not particularly limited, and sulfur crosslinking, metal salt crosslinking, peroxide crosslinking, resin crosslinking, electron beam crosslinking, and the like can be applied.
As the crosslinking agent for forming the crosslinking, sulfur, sulfur compounds, metal oxides, organic peroxides, inorganic oxides, resin crosslinking agents, and the like can be used. The type of the crosslinking agent can be appropriately selected depending on the type of rubber. Among them, it is preferable that peroxide crosslinking using an organic peroxide is formed for the silicone rubber constituting the inner layer 16, and sulfur or a sulfur compound is used for the EPDM rubber or urethane rubber constituting the outer layer 17. Preferably, sulfur crosslinking (vulcanization) or peroxide crosslinking using an organic peroxide is formed. Depending on the use conditions, blooming may occur on the roller surface due to sulfur crosslinking or peroxide crosslinking, and in this case, resin crosslinking using a resin crosslinking agent may be formed.

  Sulfur compounds such as tetramethylthiuram monosulfide (TMTM), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), tetrabutylthiuram disulfide (TBTD) or dipentamethylenethiuram tetrasulfide (DPTT) Compound: 2-mercaptobenzothiazole (MBT), dibenzothiazyl disulfide, 2-mercaptobenzothiazole zinc salt (ZnMBT), 2-mercaptobenzothiazole sodium salt (NaMBT), cyclohexylamine salt of 2-mercaptobenzothiazole (CMBT) Or a thiazole compound such as 2- (2,4-dinitrophenylthio) benzothiazole (DPBT); N-cyclohexyl-2-benzothiazo Rusulfenamide (CBS), Nt-butyl-2-benzothiazole sulfenamide (BBS), N-oxytylene-2-benzothiazole sulfenamide (OBS), N, N′-diisopropyl-2-benzothiazole Sulfenamide compounds such as sulfenamide (DPBS) or N, N′-dicyclohexyl-2-benzothiazole sulfenamide; dimethyldithiocarbamate, diethyldithiocarbamate, di-n-butyldithiocarbamate, pentamethylene Examples include dithiocarbamate metal salt compounds such as dithiocarbamate and ethylphenyldithiocarbamate. These may be used alone or in combination of two or more.

  Examples of the metal oxide include zinc oxide, magnesium oxide, and aluminum oxide. These may be used alone or in combination of two or more.

Examples of the organic peroxide include dicumyl peroxide (DCP), 1,4-bis (t-butylperoxyisopropyl) benzene, 1,1-bis (t-butylperoxyisopropyl) -3,3,5. -Trimethylcyclohexane, 2,5-dimethyl-2,5-di (t-butylperoxy) -3-hexyne, n-butyl-4,4-bis (t-butylperoxy) valerate, 2,5-dimethyl Examples include -2,5-di (t-butylperoxy) hexane. These may be used alone or in combination of two or more. Of these, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane is preferably used.
Examples of the inorganic peroxide include hydrogen peroxide.

  Examples of the resin cross-linking agent include phenol resin, melamine / formaldehyde resin, triazine / formaldehyde condensate, hexamethoxymethyl / melamine resin, and the like. These may be used alone or in combination of two or more. Among these, it is preferable to use a phenol resin, and it is more preferable to use an alkylphenol / formaldehyde resin or a halide thereof.

The blending amount of the crosslinking agent can be appropriately selected according to the type of the crosslinking agent or the type of the rubber component.
When sulfur or / and a sulfur compound is used as the crosslinking agent, the amount is preferably 0.2 to 5 parts by mass, more preferably 0.5 to 3 parts by mass with respect to 100 parts by mass of the rubber component. When using an organic peroxide as a cross-linking agent, the compounding amount is preferably 0.2 to 3.0 parts by mass with respect to 100 parts by mass of the rubber component.
When using a resin crosslinking agent as a crosslinking agent, it is preferable that the compounding quantity is 2-20 mass parts with respect to 100 mass parts of rubber components.

A vulcanization accelerator, a vulcanization acceleration aid, a co-crosslinking agent, a crosslinking activator, or the like may be used together with the crosslinking agent.
As the vulcanization accelerator, inorganic accelerators such as slaked lime, magnesia (MgO) or risurge (PbO) and organic accelerators described below can be used. Examples of organic accelerators include thiazoles such as 2-mercapto-benzothiazole or dibenzothiazyl disulfide; sulfenamides such as N-cyclohexyl-2-benzothiazylsulfenamide; tetramethylthiuram monosulfide, tetramethylthiuram Examples include thiurams such as disulfide, tetraethylthiuram disulfide or dipentamethylenethiuram tetrasulfide; thioureas such as tetramethylthiourea, trimethylthiourea or ethylenethiourea, and these can be used alone or in appropriate combination. As for the compounding quantity of a vulcanization accelerator, 0.5-5 mass parts is preferable with respect to 100 mass parts of rubber components.
Examples of the vulcanization acceleration aid include metal oxides such as zinc oxide (zinc white); fatty acids such as stearic acid, oleic acid, and cottonseed fatty acid; and other conventionally known vulcanization acceleration aids. The addition amount of the vulcanization accelerator is preferably 0.5 to 10 parts by mass and more preferably 2 to 8 parts by mass with respect to 100 parts by mass of the rubber component.
In addition, when using sulfur or / and a sulfur compound as a crosslinking agent, it is preferable to mix | blend a vulcanization accelerator or / and a vulcanization acceleration adjuvant.

The co-crosslinking agent itself functions to crosslink and react with rubber molecules to crosslink and polymerize the whole. In particular, when an organic peroxide is used as a cross-linking agent, the molecular weight of the cross-linking molecule is increased and the wear resistance can be improved by co-crosslinking with the co-crosslinking agent.
As the co-crosslinking agent, for example, a polyfunctional monomer, a metal salt of methacrylic acid or acrylic acid, a methacrylic acid ester, an aromatic vinyl compound, a heterocyclic vinyl compound, an allyl compound, or a functional group of 1,2-polybutadiene is used. Examples include polyfunctional polymers and dioximes.
When the co-crosslinking agent is blended with the organic peroxide, the amount of the co-crosslinking agent can be appropriately selected depending on the type of the co-crosslinking agent or other components used, but with respect to 100 parts by mass of the rubber component. And preferably 5 to 20 parts by mass, more preferably 10 to 15 parts by mass.

As the crosslinking activator, a metal oxide is used, and zinc oxide and zinc carbonate are particularly preferable. It is preferable that the compounding quantity of a crosslinking activator is 0.5-10 mass parts with respect to 100 mass parts of rubber components, Furthermore, it is more preferable that it is 1-5 mass parts.
In addition, when using a resin crosslinking agent as a crosslinking agent, it is preferable to mix | blend a crosslinking activator.

In addition to the rubber component and the crosslinking agent for crosslinking the rubber component, additives such as a softening agent, a filler, a reinforcing agent, a colorant, or an anti-degradation agent are appropriately blended in the inner layer 16 and the outer layer 17 as necessary. May be.
An oil or a plasticizer is used as the softening agent. It is possible to adjust the hardness of the inner layer and the outer layer by adding a softener. As the oil, for example, paraffinic, naphthenic and aromatic mineral oils, synthetic oils composed of hydrocarbon oligomers, process oils and the like can be used. Here, as the synthetic oil, for example, α-olefin oligomer, butene oligomer, amorphous oligomer of ethylene and α-olefin, and the like are preferable. As the plasticizer, for example, dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl separate (DOS), dioctyl adipate (DOA), di- (butoxy ethoxy ethyl) adipate, etc. can be used. Of these, di- (butoxy ethoxy ethyl) adipate is preferable.

The blending amount of the softener in the inner layer 16 is preferably 0 to 30 parts by mass, more preferably 0 to 15 parts by mass, and still more preferably not compounded at all with respect to 100 parts by mass of the rubber component. This is because the smaller the blending amount of the softening agent, the less the risk of shifting to the outer layer or bleeding, and the more the effects of the invention of improving the wear resistance of the outer layer and reducing the conveyance failure and squealing phenomenon are sufficiently exhibited.
The blending amount of the softening agent in the outer layer 16 can be appropriately selected according to the type of rubber component or the like from the amount that the hardness can be adjusted to a desired value and the softening agent does not bleed and contaminate other members. Specifically, it is preferably 20 to 300 parts by mass with respect to 100 parts by mass of the rubber component.

As said filler, ceramic powder, wood powder, etc. other than mineral inorganic fillers, such as calcium carbonate, titanium oxide, and magnesium carbonate, can be mentioned. By adding such a filler, the mechanical strength of the paper feed roller of the present invention can be improved. In the present invention, it is preferable to add a mineral inorganic filler to the rubber composition constituting the outer layer.
The filler is preferably blended at 25% by mass or less, more preferably at 20% by mass or less of the total mass of the composition constituting the inner layer 16 or the outer layer 17. This is because the blending of the filler is effective in improving the tensile strength and tear strength of the paper feed roller of the present invention, but if too much is blended, the flexibility tends to decrease and the friction coefficient of the roller tends to decrease. It is.

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 paper feed roller of the present invention. As the carbon black, for example, carbon black such as HAF, MAF, FEF, GPF, SRF, SAF, MT, and FT can be used.
The particle size of carbon black is preferably 10 μm or more and 100 μm or less from the viewpoint of dispersibility in the rubber composition.
In the present invention, from the viewpoint of increasing rubber strength, it is particularly preferable to add carbon black to the rubber composition constituting the outer layer.

  As a preferable blending example of the rubber composition constituting the inner layer 16, a blend of 0.2 to 1 part by weight of an organic peroxide with respect to 100 parts by weight of the silicone rubber can be given.

As a preferable blending example of the rubber composition constituting the outer layer 17, 1 to 60 parts by mass of a mineral inorganic filler, 0 to 140 parts by mass of paraffin oil, and 0 to 5 parts by mass with respect to 100 parts by mass of EPDM rubber. The compound which mix | blended with the reinforcing agent of the part can be mentioned.
Further, as other preferable blending examples, 1 to 30 parts by mass of a mineral inorganic filler and 50 parts by mass or less of a softener, particularly di- (butoxy ethoxy ethyl) adipate, relative to 100 parts by mass of urethane rubber. And 0 to 5 parts by mass of a reinforcing agent.
As the mineral filler, silicon oxide, calcium carbonate, titanium oxide or the like is preferably used alone or in combination of two or more.
As a cross-linking agent, 0.5 to 2 parts by mass of powdered sulfur is used with respect to 100 parts by mass of the rubber component in any embodiment, and together with this, a thiazole type such as 1 to 5 parts by mass of dibenzothiazyl disulfide or / and Use a thiuram vulcanization accelerator such as tetramethylthiuram monosulfide and a vulcanization accelerator such as 4 to 8 parts by mass of a metal oxide such as zinc oxide (zinc white) and / or a fatty acid such as stearic acid. It is preferable.

The paper feed roller of the present invention can be manufactured by a known method.
In order to obtain a roller-shaped molded product of the crosslinked rubber composition, the above raw materials are first kneaded. Even if the kneaded product is crosslinked before or after molding, the kneaded product is kneaded in order to shorten the working time. It may be performed simultaneously with the molding of the product. When a roller-like rubber layer is produced by crosslinking simultaneously with the molding of the kneaded product, a mold having a desired tube shape is heated, and the kneaded product is filled into the heated mold, followed by compression molding. (Press vulcanization).

  Adjustment of the rubber composition constituting each of the inner layer and the outer layer may be carried out by a conventional method conventionally performed. For example, a rubber composition can be obtained by kneading a compound comprising a rubber component, a crosslinking agent and other additives using a known rubber kneading apparatus such as an open roll, a Banbury mixer or a kneader. The temperature of the compound during kneading is, for example, 70 ° C. to 100 ° C., and the kneading time is, for example, 3 minutes to 10 minutes.

  Examples of the vulcanization / molding method of the rubber composition include extrusion molding and transfer molding. For example, the rubber composition is vulcanized by introducing an unvulcanized rubber composition into a predetermined transfer mold and heating it at a temperature of 150 ° C. to 200 ° C. for about 5 minutes to 30 minutes. And forming into a tube shape at the same time. Thereafter, the molded rubber tube is polished with a cylindrical polishing disk until it has a desired outer diameter, and is cut into a desired length, whereby the inner rubber layer 16 and the outer rubber layer 17 can be obtained.

  In this way, each rubber layer is molded separately, and the inner rubber layer is press-fitted into the hollow portion of the outer rubber layer, or the outer rubber layer is extrapolated and adhered to the inner rubber layer. Can be obtained. At this time, the outer layer is fitted and integrated on the outer peripheral surface of the inner layer without an adhesive. In this case, it is desirable that the inner diameter φa of the outer layer 17 is slightly smaller than the outer diameter φb of the inner layer 16. Specifically, the ratio of inner diameter φa / outer diameter φb is desirably set to 0.80 to 0.95.

Hereinafter, Examples 1-2, Reference Example 1, and Comparative Examples 1-3 of the paper feed roller of the present invention will be described in detail.
First, rubber compositions were prepared according to the formulas A to G shown in Table 1. In Table 1, the unit of the numerical value indicating the component amount is part by mass.

Each component described in Table 1 is as follows.
Silicone rubber A: “XE20-C0510 (trade name)” manufactured by GE Toshiba Silicones Co., Ltd.
・ Silicone rubber B: “TSE2913u (trade name)” manufactured by GE Toshiba Silicones Co., Ltd.
EPDM rubber A: “Esprene 670F (trade name)” manufactured by Sumitomo Chemical Co., Ltd. (oil-extended rubber comprising 50% by mass of EPDM rubber and 50% by mass of extended oil)
EPDM rubber B: “Esplen 505A (trade name)” manufactured by Sumitomo Chemical Co., Ltd.
・ Silicon oxide: “Nippeal VN3 (trade name)” manufactured by Nippon Silica Kogyo Co., Ltd.
・ Calcium carbonate: “BF300 (trade name)” manufactured by Bihoku Flour Industry Co., Ltd.
・ Titanium oxide: “Kronos titanium oxide KR380 (trade name)” manufactured by Titanium Industry Co., Ltd.
・ Carbon black; “Seast SO (trade name)” manufactured by Tokai Carbon Co., Ltd.
Paraffin oil: “PW-380 (trade name)” manufactured by Idemitsu Kosan Co., Ltd.
・ Zinc oxide: "Zinc oxide type 2 (trade name)" manufactured by Mitsui Mining & Smelting Co., Ltd.
・ Stearic acid: “Tsubaki (trade name)” manufactured by NOF Corporation
・ Sulfur powder: Powder sulfur manufactured by Tsurumi Chemical Co., Ltd. ・ Vulcanization accelerator A: Dibenzothiazyl sulfide (“Noxeller DM (trade name)” manufactured by Ouchi Shinsei Chemical Co., Ltd.)
・ Vulcanization accelerator B: Tetraethylthiuram disulfide ("Noxeller TET (trade name)" manufactured by Ouchi Shinsei Chemical Co., Ltd.)
Peroxide: 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (“TC-8 (trade name)” manufactured by GE Toshiba Silicone Co., Ltd.)

(Comparative Example 1)
Here, a rubber roll having a solid (single layer) structure was produced in the following manner.
First, the rubber composition of Formulation E was introduced into a predetermined mold and press vulcanized at 170 ° C. for 20 minutes to produce a cot having an inner diameter φ9 mm, an outer diameter φ21 mm, and a length 38 mm. The cot was polished with a cylindrical polishing disk until the outer diameter was 20 mm, and cut to a length of 10 mm. The rubber roll obtained by cutting was inserted into a dedicated core as a paper feed roller.

(Examples 1-2, Reference Example 1 and Comparative Examples 2-3)
(I) Preparation of inner layer A rubber composition having a predetermined composition shown in Tables 1 and 2 was introduced into a predetermined mold, and press vulcanized at 160 ° C. for 30 minutes, and had an inner diameter of 9 mm, an outer diameter of 15 mm, and a length of 60 mm. A cot was made. This cot was cut into a length of 10 mm to form an inner rubber layer.
(Ii) Preparation of outer layer A rubber composition having a predetermined composition shown in Tables 1 and 2 was introduced into a predetermined mold, and press vulcanized at 160 ° C. for 20 minutes to obtain an inner diameter of φ14 mm, an outer diameter of φ21 mm, and a length of 60 mm. A cot was made. The cot was polished with a cylindrical polishing disk until the outer diameter was φ20 mm, and cut to a length of 10 mm to produce an outer rubber layer.
(Iii) Fabrication of paper feed roller having a two-layer structure A dedicated core body is inserted into the hollow portion of the inner rubber layer, and the outer rubber layer is fitted to the outer peripheral surface of the inner rubber layer without using an adhesive. Thus, a paper feed roller was produced.

Evaluation of the paper feed roller shown in Table 2 was performed as follows.
(Inner and outer layer hardness)
The JIS-A hardness was measured with a testing machine durometer type A according to the description of “Hardness test method of vulcanized rubber and thermoplastic rubber” of JIS K6253. This hardness is the same as the conventional Shore A which is an international standard. Table 2 shows the JIS-A hardness of the inner layer and the outer layer, and the JIS-A hardness difference between the inner layer and the outer layer.

(Initial friction coefficient)
The coefficient of friction was measured by the method schematically shown in FIG.
First, 60 mm × 210 mm size P paper 20 (manufactured by Fuji Xerox Co., Ltd.) having one end connected to a load cell 19 between a paper feed roller 10 and a fixed plate 18 made of polytetrafluoroethylene (PTFE). The other end was clamped. Next, a vertical load W of 250 gf was applied from the paper feed roller 10 toward the plate 18.
Next, the paper feed roller 10 was rotated at a peripheral speed of 300 mm / second in the direction indicated by the arrow R in FIG. 4 under the conditions of a temperature of 23 ° C. and a humidity of 55%. And the conveyance force F applied to the load cell 19 at this time was measured. The friction coefficient μ was determined from the measured conveying force F (gf) and load W (W = 250 gf) using the following formula 1.
<Formula 1> μ = F (gf) / 250 (gf)
In order for the paper feed roller to perform a desired function, it is considered that an initial friction coefficient of at least 1.5 or more is necessary.

(Paper evaluation)
A paper feeding roller was attached to a copying machine “VIVECE 455 (trade name)” manufactured by Fuji Xerox Co., Ltd., and 50,000 sheets of P paper (Fuji Xerox Co., Ltd.) were passed through to observe the state of paper passing.
The paper passing status was judged in two stages: ○: good, x: non-feed and double feed.

(Friction coefficient after passing paper)
After the above paper passing evaluation, the paper feed roller was detached from the copying machine, and the friction coefficient of the paper feed roller after passing the paper was measured by the same method as in the case of the initial friction coefficient.
In order to recognize that the paper feed roller has sufficient durability, it is considered that at least 1.2 or more is necessary as a coefficient of friction after paper passing.

(Squeal evaluation)
A paper feeding roller was attached to a copying machine “VIVECE 455 (trade name)” manufactured by Fuji Xerox Co., Ltd., and 1000 sheets of P paper (Fuji Xerox Co., Ltd.) was passed through to confirm the presence of noise.
When a squeal occurred while passing 1000 sheets, it was evaluated as “Yes”, and when no squeal occurred, “None” was evaluated.

  In the case of the paper feed roller of Comparative Example 1 having a one-layer structure, the paper passing evaluation was good, but the occurrence of squeal was observed. In addition, the ratio of the friction coefficient after passing the paper to the initial friction coefficient was approximately 0.79, and the decrease in the friction coefficient was relatively large.

  In the case of the paper feed roller of Comparative Example 2 having a two-layer structure, the paper passing evaluation was good, but the occurrence of squealing was observed because the JIS-A hardness of the inner layer was too high at 15 degrees. In addition, the ratio of the coefficient of friction after passing paper to the initial coefficient of friction was about 0.75, and the decrease in the coefficient of friction was relatively large.

  In addition, in the case of the paper feed roller of Comparative Example 3 having a two-layer structure, no squeal was observed, but the outer layer JIS-A hardness was too low at 20 degrees. The practical level was not reached. In addition, the coefficient of friction after passing paper could not be measured.

On the other hand, in the case of the paper feed rollers of Examples 1 and 2 , since the JIS-A hardness of the inner layer was 10 degrees or less and the JIS-A hardness of the outer layer was 25 degrees or more and 30 degrees or less, generation of squeal was observed. In addition, the paper passing evaluation was also good. Further, the ratio of the friction coefficient after passing through the paper to the initial friction coefficient was almost 0.94 or more, and almost no decrease in the friction coefficient was observed.

It is a schematic perspective view of the paper feed roller of this embodiment. It is a cross-sectional schematic diagram which shows an example of the paper feed mechanism using the paper feed roller of this embodiment. It is sectional drawing of the paper feed roller of this embodiment. It is a figure which shows typically the method of measuring the friction coefficient of a paper feed roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Paper feed roller 11 Core body 12 Separation pad 13 Tray 14 Substrate 15 Paper 16 Outer rubber layer 17 Inner rubber layer 18 PTFE board 19 Load cell 20 P paper

Claims (6)

It has two rubber layers, an inner layer and an outer layer, and the outer peripheral surface of the inner layer and the inner peripheral surface of the outer layer are in close contact with each other without a gap,
While the inner layer contains silicone rubber as a rubber component, the inner layer has a JIS-A hardness of 10 degrees or less and a thickness of 2 mm to 10 mm ,
The outer layer contains only EPDM rubber and / or urethane rubber as a rubber component, the hardness of the outer layer is 25 degrees or more and 30 degrees or less , and the thickness is 1 mm or more and 8 mm or less ,
The paper feed roller, wherein the inner layer and the outer layer are non-foamed layers. The inner layer has a JIS-A hardness of 5 degrees or more, and the outer layer has a JIS-A hardness of 30 degrees or less,
The paper feed roller according to claim 1, wherein a difference between the JIS-A hardness of the outer layer and the JIS-A hardness of the inner layer is 15 degrees to 25 degrees.   3. The paper feed roller according to claim 1, wherein the outer layer is externally fitted to and integrated with an outer peripheral surface of the inner layer without using an adhesive. 4.   The paper feed roller according to any one of claims 1 to 3, wherein an initial friction coefficient of an outer peripheral surface of the outer layer is 1.5 or more.   The paper feed roller according to any one of claims 1 to 4, wherein a softening agent is blended in the inner layer in a ratio of 0 to 100 parts by mass with respect to 100 parts by mass of the rubber component.   The paper feed roller according to any one of claims 1 to 5, wherein the silicone rubber contained in the inner layer has a tensile stress of 0.1 to 0.5 MPa at 100% elongation and an elongation of 700% or more.

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