JP2007091371A - Elastic roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an elastic roller capable of realizing the adequate friction coefficient in the forward rotation and the reverse rotation, respectively, excellent in the wear resistance and the printing durability, and free from any occurrence of a problem of generation of roller dent, deposition of paper powder or the like. <P>SOLUTION: The elastic roller 10 comprises a core 1 and an annular elastic body 2 consisting of at least one elastic layer carried by an outer circumferential surface of the core 1, and a plurality of projecting parts 3 having directivity toward the circumferential direction is formed on the surface of the elastic layer forming an outermost layer of the annular elastic body 2. The elastic layer forming the outermost layer consists of a rubber or a thermoplastic elastomer containing carbon black having the DBP oil absorption of 100-130 ml/100g, and the mean grain size of 20-55 nm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an elastic roller (hereinafter also simply referred to as “roller”), and more specifically, in an image forming apparatus such as a copying machine or a printer, paper conveyance such as a paper feed roller, a pickup roller, a feed roller, a retard roller, and a transfer roller. The present invention relates to an elastic roller suitably used as a roller member having a function.

  A roller member having a paper conveyance function used in an image forming apparatus such as a copying machine or a printer generally has a structure in which an elastic layer made of a rubber material or the like is supported on the outer periphery of a core, and the paper is formed on the surface of the elastic layer. The material is conveyed by friction between the elastic layer and the paper in contact with the (transfer object).

  Therefore, in the rubber roller in which the elastic layer is formed of a rubber material, carbon black is hardly added to the rubber compound (about 1 part of the coloring level even when added) from the consideration of paper stains. in use. On the other hand, some roller members such as a pinch roller and a paper discharge roller that do not require a high coefficient of friction contain a large amount of carbon black.

As an improved technique related to a roller used for transporting paper, for example, Patent Document 1 discloses that a paper feeding roller that can maintain a coefficient of friction necessary for transporting paper even when ink adheres to the roll surface is realized. As an object, there is described a technique in which a forward polishing eye and a reverse polishing eye are present on the roller surface in a predetermined area ratio.
JP 2005-15097 A (Claims etc.)

  By the way, in a paper feed mechanism using a paper feed roller and a separation pad or a paper feed roller and a separation claw, as in an ink jet printer, the roller rotates in the order of normal rotation, reverse rotation, and normal rotation to pull in the paper. , Position correction, and transport operations. In this series of operations, the higher the friction coefficient (μ) of the roller during forward rotation for pull-in and conveyance, the better. On the other hand, during reverse rotation that operates for position correction, the μ is lower than during forward rotation. Is preferred. More preferably, μ can be adjusted between forward rotation and reverse rotation. However, it cannot be controlled by the white rubber system currently used for the paper feed roller, such as a film paper such as an OHP film or an ink jet printer. Photographic media paper has the drawback that the print quality deteriorates due to roller marks.

  Therefore, the object of the present invention is to express an appropriate coefficient of friction at the time of forward rotation and at the time of reverse rotation, which is excellent in wear resistance and printing durability, as well as problems such as generation of roller marks and adhesion of paper dust. The object is to provide an elastic roller that does not generate.

  In order to solve the above problems, the present inventor has intensively studied, and as a result, a convex portion having a directivity in the circumferential direction is formed on the surface of the elastic layer, and a specific carbon black is blended with the base material of the elastic roller. Thus, the inventors have found that an elastic roller that expresses a desired coefficient of friction different between forward rotation and reverse rotation and that can satisfy other required characteristics can be realized, and has completed the present invention.

That is, the elastic roller of the present invention includes a core body and an annular elastic body composed of at least one elastic layer carried on the outer peripheral surface of the core body, and the surface of the elastic layer forming the outermost layer of the annular elastic body In addition, an elastic roller in which a plurality of convex portions having directivity in the circumferential direction are formed,
The elastic layer constituting the outermost layer is made of rubber or thermoplastic elastomer containing carbon black having a DBP oil absorption of 100 to 130 ml / 100 g and an average particle diameter of 20 to 55 nm.

  In the present invention, it is preferable to use one or both of HAF grade carbon black and FEF grade carbon black as the carbon black. Moreover, the compounding amount of the carbon black is preferably 5 to 30 parts by weight with respect to 100 parts by weight of the rubber or thermoplastic elastomer. Further, in the elastic roller of the present invention, it is preferable that the difference in friction coefficient between the forward rotation and the reverse rotation is 0.2 or more.

  Furthermore, in the present invention, the annular elastic body includes an outer elastic layer that is a non-foamed layer and an inner elastic layer that is a foamed layer, and the outer elastic layer as an elastic layer that forms the outermost layer. It is preferable that the plurality of convex portions are formed on the surface. The elastic roller of the present invention preferably has a JIS-A hardness of 15 to 40 and is preferably used as a paper feed roller.

  As described above, according to the present invention, it is possible to express an appropriate friction coefficient at the time of forward rotation and at the time of reverse rotation, and it is excellent in wear resistance and printing durability, as well as generation of roller marks and paper. It has become possible to realize an elastic roller that does not cause problems such as powder adhesion.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings.
1A and 1B are schematic sectional views of the elastic roller of the present invention. As shown in the figure, an elastic roller 10 of the present invention comprises a core body 1 and an annular elastic body 2 composed of at least one elastic layer carried on the outer peripheral surface thereof. A plurality of convex portions 3 having a directionality in the circumferential direction are formed on the surface of the elastic layer forming the structure.

  In the roller 10 according to the present invention, by providing a plurality of convex portions 3 having such directivity on the surface of the outermost elastic layer, the direction in which the convex portions 3 increase friction with respect to the paper 20 as shown in the drawing. (For forward rotation (a)) or in a direction to reduce friction (reverse rotation (b)), contact in different states during forward and reverse rotation, thereby expressing different friction coefficients during forward and reverse rotation Is possible. In addition, the convex part 3 may be formed as a polishing line by surface polishing, and may form a desired convex part pattern by shaping | molding. The size of the polishing mesh can be, for example, about 10 to 90 μm. In the case of a convex pattern, for example, the pattern of convex portions extending in the longitudinal direction having a height of about 20 to 100 μm can be used. . Specifically, the convex portion is formed by molding, for example, by performing vulcanization molding of a roller in a mold having an inner surface provided with a desired concave portion by chemical etching or electric discharge machining, or depending on the shape of a die used for extrusion molding. It can be performed by a method such as forming a desired convex portion on the roller surface.

  In the present invention, the elastic layer forming the outermost layer of the annular elastic body 2 has a DBP oil absorption of 100 to 130 ml / 100 g, preferably 110 to 120 ml / 100 g, an average particle size of 20 to 55 nm, preferably 25 to 25 nm. It consists of rubber or thermoplastic elastomer containing 50 nm carbon black. By adding carbon black that satisfies the specified physical properties in the outermost elastic layer, the friction coefficient in the forward rotation direction of the roller can be increased. On the other hand, the friction coefficient in the reverse rotation direction increases as the number of added parts increases. Can be reduced.

  The carbon black added to the outermost elastic layer is not particularly limited as long as it satisfies the DBP oil absorption amount and the average particle diameter. For example, HAF grade carbon black and FEF grade carbon black are used. These can be used preferably, and these may be used alone or in combination of two or more.

  Further, the blending amount of carbon black is preferably 5 to 30 parts by weight with respect to 100 parts by weight of rubber or thermoplastic elastomer, thereby increasing the resilience of the outermost elastic layer, so that the outermost layer of the roller. It is possible to appropriately increase the coefficient of friction with respect to the paper while maintaining the hardness that can be used as the elastic layer.

  In the present invention, since it is configured as described above, an elastic roller having a difference in friction coefficient between forward rotation and reverse rotation of 0.2 or more can be realized. Therefore, the roller of the present invention is an electrophotographic printer, When mounted on a copying machine, especially an ink jet printer, etc., it has the property that paper dust does not easily adhere to the roller surface even during transport of various types of paper, and can exhibit stable paper passing performance over a long period of time. . The roller of the present invention also prevents the occurrence of roller traces (generated at the contact start point between the roller and the paper) that are likely to occur when transporting special media paper used in OHP sheets or inkjet printers. It is extremely effective. Furthermore, it is provided to prevent paper double feeding in printers and printers using separation pads and separation claw type paper feed mechanisms, printers and copying machines using general-purpose electrophotographic mechanisms, and paper. By using it for a retard roller, a feed roller, a pickup roller, etc., it is possible to obtain a high quality image. The JIS-A hardness of the roller of the present invention is preferably about 15 to 40.

  In the roller of the present invention, as long as the above conditions are satisfied for the outermost elastic layer, the specific material and layer configuration are not particularly limited, and can be appropriately determined according to the application. In particular, the annular elastic body 2 is composed of an outer elastic layer that is a non-foamed layer and an inner elastic layer that is a foamed layer, and the surface of the outer elastic layer serving as the outermost elastic layer is It is preferable that a plurality of convex portions 3 are formed. By providing the foam layer as the inner elastic layer, the effect of further improving the resilience of the roller can be obtained. The elastic layer forming the outermost layer is preferably a non-foamed layer.

  The material of the elastic layer, which is a non-foamed layer applicable to the present invention, is not particularly limited, and can be appropriately selected from conventionally known rubbers and thermoplastic elastomers. From the viewpoint of wear resistance, rubber is preferred. Specific examples include the following.

  Examples of rubber include ethylene propylene rubber (EPR), ethylene propylene diene terpolymer rubber (EPDM), natural rubber, isoprene rubber, styrene butadiene rubber, polynorbornene rubber, butadiene rubber (BR), and nitrile rubber (NBR). ), Chloroprene rubber (CR), butyl rubber, halogenated butyl rubber, acrylic rubber, ethylene-vinyl acetate rubber (EVA), general rubber such as urethane rubber, silicone rubber, fluorine rubber, ethylene acrylic rubber, polyester elastomer, epichlorohydrin rubber, polysulfide Special rubbers such as rubber, Hypalon (registered trademark), and chlorinated polyethylene are listed. Among them, ethylene propylene rubber, ethylene propylene diene terpolymer rubber, natural rubber, isoprene rubber, styrene butter Engomu, polynorbornene rubber, butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, halogenated butyl rubber, acrylic rubber, epichlorohydrin rubber and chlorinated polyethylene rubber is preferred. These rubbers can be used alone or in combination of two or more.

  As the thermoplastic elastomer, for example, any of polyolefin-based, polyurethane-based, polyester-based, polyamide-based, polystyrene-based, etc. can be selected and used. Among them, hard blocks such as crystal structures and agglomerated structures can be used. It is particularly preferable to have a portion that is easy to form and a soft block such as an amorphous structure, and specific examples include (1) to (3) below.

(1) A block copolymer of crystalline polyethylene and ethylene / butylene-styrene random copolymer obtained by hydrogenating a block copolymer of polybutadiene and butadiene-styrene random copolymer.
(2) Obtained by hydrogenating a block copolymer of polybutadiene and polystyrene, or a block copolymer of polybutadiene or ethylene-butadiene random copolymer and polystyrene, for example, a diblock of crystalline polyethylene and polystyrene Block copolymer, styrene-ethylene / butylene-styrene triblock copolymer, styrene-ethylene / propylene-styrene triblock copolymer, among others, styrene-ethylene / butylene-styrene block copolymer or styrene- Ethylene / propylene-styrene block copolymer.
(3) A block copolymer in which crystalline polyethylene is linked to one end or both ends of an ethylene / butylene copolymer.

  Among these, a block copolymer comprising at least one polymer block mainly composed of a vinyl aromatic compound and at least one polymer block mainly composed of a conjugated diene compound mentioned in (2). A hydrogenated block copolymer obtained by hydrogenation and having a number average molecular weight of 150,000 to 400,000 is preferable. These thermoplastic elastomers can be used alone or in combination of two or more.

  These rubbers and thermoplastic elastomers can be blended with a softener, if desired, in order to adjust the hardness. The softener is not particularly limited, and is appropriately selected from those conventionally used as plastics and rubber softeners, for example, various rubber or resin softeners such as mineral oils, vegetable oils, and synthetics. can do. Here, process oils such as naphthenic and paraffinic are exemplified as mineral oils, and as a vegetable oil, castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, Examples include wax, pine oil, and olive oil. In addition, these softeners may be used individually by 1 type, and may mix and use 2 or more types if mutual compatibility is favorable.

  In addition to the rubber and thermoplastic elastomer, inorganic additives such as clay, diatomaceous earth, silica, talc, barium sulfate, calcium carbonate, magnesium carbonate, metal oxide, mica, graphite, aluminum hydroxide and the like should be appropriately blended. Thus, tackiness on the surface of the non-foamed elastic layer can be improved, but silica is particularly preferred from the viewpoint of reducing the environmental change of tackiness.

  Moreover, you may mix | blend the following fillers with the said rubber | gum and thermoplastic elastomer further as needed. That is, various metal powders, wood chips, glass powders, ceramic powders, granular or powdered solid fillers such as granular or powdered polymers, and other various natural or artificial short fibers and long fibers (for example, straw, hair, glass Fiber, metal fiber, and other various polymer fibers).

  As a material of the inner elastic layer which is a foam layer, in addition to polyurethane, polyethylene and polystyrene, a blended member obtained by adding a foaming agent to the above rubber material or thermoplastic elastomer as a material of the non-foam layer elastic layer may be used. As the foaming agent, 4,4 ′ oxybis (benzene) sulfonyl hydrazide (OBSH), azodicarbonamide (ADCA), or the like can be used.

  Moreover, there is no restriction | limiting in particular as the material of the core 1 of an elastic roller, The thing conventionally used as a core in the conventional roller member can be used. Specific materials include plastics such as acrylonitrile butadiene styrene resin (ABS), polyacetal (POM), polycarbonate (PC), polyamide (nylon), and metals such as aluminum, SUS, and magnesium alloys. It may be appropriately selected and used accordingly. Needless to say, the annular elastic body 2 in the elastic roller 10 of the present invention does not need to be mounted over the entire length of the core body 1, and a plurality of appropriate lengths are appropriately used. It can be installed at intervals. The elastic roller of the present invention can be manufactured according to a conventional method and is not particularly limited.

Hereinafter, the present invention will be described in more detail with reference to examples.
In accordance with the composition shown in Table 1 and Table 2 below, as shown in FIG. 1, an annular elastic material comprising a single non-foamed elastic layer on the outer peripheral surface of the core 1 (material: polyacetal resin (POM), outer diameter φ20 mm). The elastic roller 10 provided with the body 2 and having a plurality of convex portions 3 formed on the surface thereof having directivity in the circumferential direction was produced. The convex portion 3 was formed by polishing the roller surface.

An elastic roller having an annular elastic body composed of an outer elastic layer that is a non-foamed layer and an inner elastic layer that is a foamed layer, and a plurality of convex portions having a direction in the circumferential direction formed on the surface of the outer elastic layer. For the outer elastic layer, according to the formulation shown in Table 3 below, for the inner elastic layer, ADCA (Neoslen HM80A, manufactured by Eiwa Kasei Co., Ltd.) as a foaming agent in the outer elastic layer formulation and a foaming aid It was produced by adding 1 part by weight of urea (manufactured by Eiwa Kasei Co., Ltd., cell paste 101). The convex portion was formed by polishing the roller surface. The core body was made of POM with an outer diameter of φ12 mm, and the roller outer diameter was 24.5 mm. Further, the hardness of only the inner elastic layer was Asker C15 to 18 degrees, the foam specific gravity was 0.3, and the thickness was 4.5 mm.
The following evaluations are also shown in Tables 1 to 3 below for each of the produced elastic rollers.

(JIS-A hardness)
It measured using the JIS spring type hardness meter.

(Coefficient of friction)
Using HEIDON (manufactured by Shinto Kagaku Co., Ltd.), the coefficient of friction was measured for normal rotation and reverse rotation when using plain paper XEROX-P paper and when using OHP sheets, respectively. The measurement conditions were a temperature of 25 ° C., a humidity of 60%, a peripheral speed of 75 mm / second, and a load of 200 g.

(Taber wear)
Using a H22 grindstone, a Taber abrasion test was performed under a load of 250 g, and the amount of abrasion was measured.

(Roller passage mark)
The presence or absence of traces of the passage of the roller was determined visually. ◎ indicates excellent, ○ indicates good, Δ indicates slightly bad, and × indicates bad.

(Amount of paper dust)
The degree of adhesion of the paper dust on the roller surface was determined visually. ◎ indicates excellent, ○ indicates good, Δ indicates slightly bad, and × indicates bad.

(Print durability)
Using an apparatus as shown in FIG. 2, the printing durability was evaluated by the pseudo accelerated test method. Specifically, the test paper 12 (plain paper XEROX-P) is placed on the rotary table 11 and the roller table 13 is brought into contact with the surface of the test paper 12 while the load 14 is applied. The roller was rotated and the durability of the roller was evaluated. ◎ indicates excellent, ○ indicates good, Δ indicates slightly bad, and × indicates bad.

＊１）ＥＰＤＭ：ＥＰ９６，ＪＳＲ社製
＊２）ＨＡＦ：旭＃７０（ＤＢＰ吸油量１０１ｍｌ／１００ｇ、平均粒子径２６ｎｍ），旭カーボン（株）製
＊３）ＦＥＦ：旭＃６０（ＤＢＰ吸油量１１４ｍｌ／１００ｇ、平均粒子径４５ｎｍ），旭カーボン（株）製
＊４）ＳＲＦ：旭＃３５（ＤＢＰ吸油量５０ｍｌ／１００ｇ、平均粒子径７８ｎｍ），旭カーボン（株）製
＊５）ＦＴ：アサヒサーマル（ＤＢＰ吸油量２８ｍｌ／１００ｇ、平均粒子径８０ｎｍ），旭カーボン（株）製
＊６）炭酸カルシウム
＊７）プロセス油 ダイアナプロセスＮＳ１００，出光興産（株）製
＊８）加硫促進剤 アクセルＴＳ，川口化学工業（株）製
＊９）加硫促進剤 ノクセラーＭ，大内新興化学工業（株）製

* 1) EPDM: EP96, manufactured by JSR * 2) HAF: Asahi # 70 (DBP oil absorption 101 ml / 100 g, average particle size 26 nm), manufactured by Asahi Carbon Co., Ltd. * 3) FEF: Asahi # 60 (DBP oil absorption) 114 ml / 100 g, average particle diameter 45 nm), manufactured by Asahi Carbon Co., Ltd. * 4) SRF: Asahi # 35 (DBP oil absorption 50 ml / 100 g, average particle diameter 78 nm), manufactured by Asahi Carbon Co., Ltd. * 5) FT: Asahi Thermal (DBP oil absorption 28ml / 100g, average particle size 80nm), Asahi Carbon Co., Ltd. * 6) Calcium carbonate * 7) Process oil Diana Process NS100, Idemitsu Kosan Co., Ltd. * 8) Vulcanization accelerator Accel TS , Manufactured by Kawaguchi Chemical Industry Co., Ltd. * 9) Vulcanization accelerator Noxeller M, manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

  As shown in Tables 1 to 3 above, the outermost elastic layer contains carbon black having a predetermined DBP oil absorption amount and average particle diameter, and the elasticity of each example in which a plurality of predetermined protrusions are formed on the surface. The roller can generate an appropriate coefficient of friction during forward rotation and reverse rotation, has an appropriate JIS-A hardness, has excellent wear resistance and printing durability, and generates roller marks. It was confirmed that there was no problem such as adhesion of paper and paper dust.

(A), (b) is a schematic sectional drawing which shows the elastic roller which concerns on one embodiment of this invention. It is the schematic which shows the apparatus used for evaluation of the printing durability in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Core body 2 Annular elastic body 3 Convex part 10 Elastic roller 11 Rotary table 12 Test paper 13 Roller sample 14 Load 20 Paper

Claims (7)

A core body and an annular elastic body composed of at least one elastic layer carried on the outer peripheral surface of the core body, and the surface of the elastic layer forming the outermost layer of the annular elastic body has a directivity in the circumferential direction. An elastic roller having a plurality of convex portions,
The elastic roller, wherein the elastic layer constituting the outermost layer is made of rubber or thermoplastic elastomer containing carbon black having a DBP oil absorption of 100 to 130 ml / 100 g and an average particle diameter of 20 to 55 nm.   The elastic roller according to claim 1, wherein the carbon black is one or both of HAF grade carbon black and FEF grade carbon black.   The elastic roller according to claim 1 or 2, wherein a blending amount of the carbon black is 5 to 30 parts by weight with respect to 100 parts by weight of the rubber or the thermoplastic elastomer.   The elastic roller according to any one of claims 1 to 3, wherein a difference in friction coefficient between forward rotation and reverse rotation is 0.2 or more.   The annular elastic body is composed of an outer elastic layer that is a non-foamed layer and an inner elastic layer that is a foamed layer, and the plurality of convex portions are formed on the surface of the outer elastic layer serving as the outermost elastic layer. The elastic roller according to claim 1, wherein the elastic roller is formed.   The elastic roller according to any one of claims 1 to 5, wherein the JIS-A hardness is 15 to 40.   The elastic roller according to any one of claims 1 to 5, which is used as a paper feed roller.

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