JP2005082376A - Retard roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a retard roller capable of suppressing the lowering of the coefficient of friction with the elapse of time by forming a roller base material, which is the base portion of the retard roller, of a resin foam body capable of producing a sufficient nip thickness, and by forming the outer peripheral surface of the roller in contact with a printing medium such as paper to be retarded, of a rubber ring of EPDM rubber having both the sufficient coefficient of friction and a wear resistance. <P>SOLUTION: This retard roller comprises a core material 12 of a specified length, a roller base material 14 having, at its center, the core material 12, and formed of the resin foam body with a three-dimensional mesh skeleton, and the rubber ring 16 formed of the EPDM rubber covering the outer peripheral surface 14a of the roller base material 14. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a retard roller, and more particularly, is suitably used for an OA roller such as a copying machine or a leather printer, in particular, a pick-up roller such as a color plain page copy or a laser printer, a feed roller and a separation roller. The present invention relates to a roller for electronic equipment.

  Various rollers such as a fixing roller, a cleaning roller, and a paper feed roller are used in electronic devices such as an electronic copying machine, an electrophotographic machine, and various printers. In particular, as a roller related to paper feeding such as a retard (separation) roller, as shown in FIG. A roller 50 in which a sealing layer 55 is formed of a sealing agent and a smooth silicone rubber layer 56 made of silicone rubber or the like having a high friction coefficient is formed on the outer peripheral surface of the soft urethane roller 54 is preferably used.

Regarding the roller 50, the applicant of the present application has devised the invention "roller manufacturing method and electronic device roller manufactured by the method" described in [Patent Document 1] shown below. In the present invention, (1) there is a moderate elasticity, a large nip width is obtained with a low hardness and a low load, and the compression set is small, so that an excessive force is not applied to the roller base material. The diameter of the roller can be reduced, and the roller can be reduced in weight and size. (2) Since it has a high ability to adsorb silicone oil and has high resistance to silicone oil and does not swell and deform, it is suitable as a cleaning roller for electronic equipment. (3) Furthermore, since an extremely thin silicone rubber foam layer can be directly formed on the surface of a roller base made of metal or the like, it can be used as it is as a paper feed roller for electronic equipment. The roller for electronic devices which has the usefulness of these etc. is disclosed.
Japanese Patent Laid-Open No. 7-76049

  However, in the case of the roller 50, the silicone rubber layer 56 formed on the outermost peripheral surface has a very high coefficient of friction, but is inferior in wear resistance, and the product life is shortened in recent high-speed printing and long-term use. The difficulty that will be shortened is pointed out. The friction coefficient is determined by the softness of the silicone rubber as the raw material of the silicone rubber layer 56, that is, the amount of silicone oil contained as a softening agent. In addition, since the inclusion such as the silicone oil bleeds in use, it adversely affects the printing medium such as paper and the printing medium such as toner that the silicone rubber layer 56 is in direct contact with. In particular, color toners, which have been widely used recently, are known to be greatly affected by the above-mentioned bleed silicone-based materials and discolored. Is inherent.

  Further, in the case of the roller 50, the silicone rubber layer 56 having a predetermined thickness is uniformly applied by a means such as a doctor blade to the outer peripheral surface which has been treated so as not to penetrate into the inside by the sealing layer 55 of the soft urethane roller 54. And formed by polishing. This polishing is necessary to improve the roundness of the roller 50. Further, the surface of the silicone rubber layer 56 can be expected to have an effect of improving the shape friction by forming irregularities, so-called polishing eyes, by polishing. However, in other words, (1) the formation of the sealing layer 55 and a post-processing step for improving the roundness are necessary, and the manufacturing cost increases. As a result, the shape of the friction coefficient and the physical friction coefficient are reduced due to adhesion of fine powder such as non-contact paper to the surface of the silicone rubber layer 56 that has been scraped and smoothed in the initial stage of use. It is pointed out that this is a major drawback that the overall frictional force decreases at the initial stage of use.

Therefore, the applicant of the present application has devised the invention “roller and manufacturing method thereof” described in [Patent Document 2] shown below. As shown in FIG. 6, the present invention provides a wear-resistant coating layer having a predetermined or higher tensile strength on the outer surface 62a of an elastic roller 62 having a three-dimensional network skeleton structure without burying the three-dimensional network skeleton structure. The paper feed roller represented by the retard roller has both the frictional property developed by the shape action of the elastic roller 62 and the wear resistance developed by the physical action of the wear resistant coating layer 64. The roller 60 which can be used suitably for is provided. Here, the state of retarding by the roller 60 will be described. As shown in FIG. 7, the roller 60 comes into contact with a feeding roller 70 rotating to feed a paper 72 as a printing medium. The paper 72 that is going to be fed in excess is brought into contact with and fed back by being opposed and rotated in reverse. At this time, the roller 60 always rotates in the reverse direction with respect to the feeding roller 70 (see FIG. 7A), but the paper 72 to be fed normally is placed between the feeding roller 70 and the paper 72. When the paper is nipped and fed, it rotates in reverse with the rotation of the feed roller 70 (see FIG. 7B).
JP 2003-156032 A

  However, in the case of the roller 60 according to the above-mentioned invention “roller and manufacturing method thereof”, the elastic roller 62 basically exhibits flexibility due to its structure to ensure a nip thickness, thereby providing retardability. In addition to improving the wear resistance, the wear-resistant coating layer 64 prevents friction generated during feeding of paper as a printing medium, thereby extending the product life. In the case of the roller 60 having such a structure, the friction coefficient of the wear-resistant coating layer 64 is not necessarily high, and the friction coefficient with time is reduced due to fine powder from the paper 72 generated depending on the use frequency. It is considered a problem. This decrease in the coefficient of friction over time may cause abnormal noise, that is, so-called noise, in a low-speed copying machine of 40 sheets or less per minute. The occurrence of this squeal means a malfunction of the roller 60 related to the retard described above, and is a serious problem that requires immediate replacement.

In order to overcome the above-mentioned problems and achieve the intended purpose, the retard roller according to the present invention comprises a core material of a required length,
A roller base material made of a resin foam having a three-dimensional network skeleton, with the core material at the center;
It comprises a rubber ring made of EPDM rubber that covers the outer peripheral surface of the roller base material.

  As described above, according to the retard roller according to the present invention, the roller base material, which is the base material portion of the roller, is formed from a resin foam capable of expressing a sufficient nip thickness, and the paper to be retarded, etc. By forming the outer peripheral surface of the roller in contact with the printing medium from a rubber ring made of EPDM rubber having both a sufficient friction coefficient and wear resistance, a decrease in the friction coefficient with time can be suppressed.

  Next, a preferred embodiment of the retard roller according to the present invention will be described below with reference to the accompanying drawings. Note that the same members already described in the prior art described with reference to FIG. 7 are denoted by the same reference numerals, and detailed description thereof is omitted. The inventor of the present application uses a roller base material 14 made of a foam of a resin material such as polyurethane capable of achieving a sufficient nip thickness required as a retard roller as the inside of the roller, and is sufficient on the outer surface of the roller. It has been found that a rubber ring 16 made of EPDM rubber, which generally has both a high friction coefficient and wear resistance, can be used suitably as a retard roller by suitably bonding these two different materials. Is.

  A retard roller 10 according to a preferred embodiment of the present invention, as shown in FIG. 1, has a core 12 having a required length for pivotal support inside a color copying machine and the like, and a three-dimensional mesh skeleton. The roller base 14 is provided around the core 12 and the rubber ring 16 is bonded to the outer peripheral surface 14a of the roller base 14 and is made of EPDM (ethylene diene terpolymer) rubber. . A plurality of grooves 18 parallel to the core member 12 are formed on the outer peripheral surface 16 a of the rubber ring 16. As shown in FIG. 2, when the groove 18 is used as a retard roller 10 in a required device, the groove 18 is used to catch a paper 72, which is a printing medium to be retarded. It is configured to be able to do nothing. As the material of the core member 12, a metal such as aluminum or stainless steel or a hard resin such as ABS is preferably used with a required length, but it is particularly preferable to use a metal having excellent heat resistance. The shape of the core material employed in the present invention is preferably cylindrical from the viewpoint of weight reduction or the like, but it is of course possible to use a solid bar or prism.

  As the roller base material 14, a foam made of a resin such as polyurethane, polyethylene, or polypropylene and having a so-called three-dimensional network skeleton structure is preferably used. In particular, when considering use as a retard roller, a foam of a soft urethane resin that can easily obtain a large nip thickness, that is, flexibility is preferable. The soft urethane resin can be used without limitation as long as it can be molded. Specifically, it is a mechanical floss method, a compound system obtained by overheating and curing bubbles formed without containing a packing agent such as water, a hot mold that cures at a high temperature to promote resinification A blended system or cold mold blending in which curing is performed at a relatively low temperature using a highly active polyol and reaction curing is preferred. In order to sufficiently develop the nip thickness, the hardness of the roller base material 14 is set to 50 or less in Asker F hardness. If this value exceeds 50, a sufficient nip thickness cannot be ensured, and the retardability deteriorates.

In addition, the skeleton structure of the three-dimensional network has the above-mentioned nip thickness to be uniform, and in order to easily achieve it, the ordinary flexible urethane foam has an irregular shape without regularity like a so-called loofah skeleton. A skeleton that forms a simple cell is preferred. The number of cells representing the density of the skeleton structure of the three-dimensional network is preferably set in a range of 20 to 200 cells / 25 mm (1 inch). When the number of cells is less than 20 cells / 25 mm, a sufficient nip thickness cannot be achieved even when the hardness is less than the set value. On the other hand, manufacturing of cells exceeding 200 cells / 25 mm increases the manufacturing cost. I will. In addition, in order to achieve suitable flexibility, the density of the roller base material 14 is also a large factor. In the present invention, the density is set to a low density of about 200 kg / m ³ or less.

  The rubber ring 16 is a portion that expresses a high coefficient of friction and wear resistance by covering the entire outer surface 14a without impairing the flexibility of the roller base material 14. The material is made of EPDM rubber which is excellent in terms of ozone resistance, weather resistance, heat resistance, and particularly abrasion resistance to paper. The thickness of the rubber ring 16 is set to 2.0 mm or less at the groove 18 portion. When this thickness exceeds 2.0 mm, the flexibility that the retard roller 10 should develop is lowered, and a sufficient nip thickness cannot be secured, that is, the contact area with the paper 72 as a printing medium is reduced. . The depth of the groove 18 is set in the range of 0.1 to 1.5 mm. If this depth is less than 0.1 mm, there is a problem that the retard made by hooking the print medium in the shape of the groove 18 described above ([0013]) becomes uncertain, whereas if it exceeds 1.5 mm. As a result, the rubber ring 16 becomes thicker on average, and as a result, the flexibility that the retard roller 10 should exhibit decreases, and a sufficient nip thickness cannot be secured, or the paper 72 that should be fed originally. The problem of being retarded will occur. Further, the interval between the outer peripheral surfaces 16a of the grooves 18 is set to about 1 mm pitch, and at least about 50 is preferably provided on the outer peripheral surface 16a.

  The wear resistance, which is a physical property that the rubber ring 16 made of EPDM rubber should have, is set as follows. That is, the tensile strength measured according to JIS K 6251 (vulcanized rubber tensile test method) is set to 4 MPa or more. When this value is 4 MPa or more, it is found that sufficient wear resistance is exhibited by use as the present retard roller 10, and below this value, sufficient wear resistance cannot be expected. This JIS K 6251 (vulcanized rubber tensile test method) will not be described in detail, but basically, the tensile strength value according to the present invention is determined based on the type 3 or type 5 dumbbell test according to the required coating material. A piece was prepared, and this was calculated from numerical values measured under the condition of a tensile speed of 500 ± 50 mm / min using a test apparatus defined in JIS B 7721.

  EPDM rubber is produced by using either or both of commercially available oil-extended EPDM polymers and non-oil-extended EPDM polymers. The diene component of the EPDM polymer is not particularly limited, and any of ethylidene norbornene (ENB), dicyclopentagen (DCPD), and the like can be adopted. For EPDM polymers, fillers (titanium oxide, silica, carbon black, clay, talc, etc.), hydrocarbon synthetic oils as softeners, vulcanizing additives (vulcanizing agents, vulcanization accelerators, vulcanizing agents). (Sulfur accelerating auxiliary agent or vulcanization retarder, etc.), plasticizer, anti-aging agent, or other additives are blended as appropriate to form a rubber compound, which is heated to obtain an EPDM rubber.

  A predetermined amount of the adhesive component is applied to the outer surface 14a of the roller base material 14 having a three-dimensional mesh skeleton structure or the adhesive surface of the rubber ring 16 by a method such as brushing. As the adhesive component, a moisture curable one-component adhesive such as epoxy and urethane, a hot melt adhesive, or a hot melt adhesive sheet can be used. When the adhesive component is a liquid, the viscosity at the time of applying the adhesive component is set in the range of 0.05 to 2 Pa · S in order to suppress the penetration of the adhesive component into the roller base material 14. In particular, when spray coating is used as the coating method, it is set in the range of 0.001 to 0.1 Pa · S. In each method, when the viscosity is lower or higher than the predetermined viscosity, the degree of penetration into the roller base material 14 is increased, and the workability is deteriorated.

(Example of manufacturing method)
Next, an example of a method of manufacturing a retard roller according to the present embodiment and a manufacturing apparatus that suitably implements the method will be described below. The foaming raw material M, which is the raw material of the core material 12, the rubber ring 16, and the roller base material 14, is prepared in advance, and the groove 18 is formed in the rubber ring 16 at the time of manufacturing in another process or by a conventionally known method. In addition, it is processed into a ring shape, and the adhesive component is applied to the inner peripheral surface with a required basis weight.

  About the manufacturing method of the said rubber ring 16, the thickness is 2 mm or less and the groove | channel 18 is set to 0.5-1 mm, and the molding by the rubber | gum vulcanizing can is preferable from the point which raises the precision. Molding of rubber with a vulcanizing can is performed by filling the vulcanizing can with a rubber compound, and closing and heating and heating. That is, the rubber ring 16 according to the present invention is manufactured by using a predetermined mold made of upper and lower molds, setting a core in the mold, and forming a rubber compound in a cavity defined in the mold. After the mold is injected and closed, the temperature is raised to the vulcanization temperature of the mold in order to vulcanize the rubber compound. As described above ([0016]), this rubber compound is blended with an EPDM polymer and required additives and kneaded with a conventionally known kneader such as a roll or a kneader under heating at about 80 to 120 ° C. It is obtained by.

  The retard roller 10 is manufactured by a manufacturing apparatus 20 as shown in FIG. The manufacturing apparatus 20 comprises a pair of mold halves 24, 24 that define a cavity 26 having an inner contour shape that matches the outer contour shape of the retard roller 10 to be obtained inside when closed. In a so-called resin molding mold 22 having an injection hole 22a into which 30 (to be described later) is inserted, and in a storage tank (not shown) for storing a foaming raw material M as a raw material of the roller base material 14 in the cavity 26 It is basically composed of an injection tube 30 that communicates and injects the foaming raw material M. Further, support grooves 28, 28 in which the core material 12 can be arranged so as to align the cavity 26 and the central axis are provided at both ends in the longitudinal direction of the mold 22. The injection tube 30 is configured to be openable and closable under control.

  Then, as shown in FIG. 4, the core material 12 and the rubber ring 16 (with the adhesive component applied to the inner peripheral surface) are installed and closed at a required position inside the mold 22 in the open state (FIG. 4 ( see a)). At this time, the rubber ring 16 does not need to be disposed so as to be completely in contact with the inner peripheral surface of the cavity 26. This is because the inner peripheral surface of the cavity 26 is brought into a pressing state by pressing due to foaming of the foaming material M to be described later. After the mold 22 is closed, a required amount of foaming raw material M is injected and filled from the injection hole 22a through the injection pipe 30 into the cavity 26 defined (see FIG. 4B). After filling a predetermined amount, the injection tube 30 is closed. After the injection, the foaming raw material M is made into a resin and hardens while foaming over time. At this time, the foaming raw material M whose foaming is being completed is in a state where the inside of the rubber ring 16 is filled and spreads outward, thereby preliminarily adhering to the inner peripheral surface thereof. The roller base material 14 that is in a pressing state with respect to the components is obtained (see FIG. 4C).

  Adhesion between the rubber ring 16 and the roller base material 14 made of polyurethane foam or the like is preferably performed so as to be tightly fixed so that no slippage or voids are generated when the retard roller 10 is used. However, in this embodiment, the roller base material 14 is formed so as to be pressed against the inner peripheral surface of the rubber ring 16 as described above ([0021]). Due to the cured adhesive force and the adhesive component force, the rubber ring 16 is firmly bonded. Further, the core material 12 and the roller base material 14 are sufficiently firmly bonded only by the curing adhesive force of the foam raw material M. In addition, the injection amount of the foaming raw material M is calculated from the foaming magnification of the foaming raw material M and the internal volume of the cavity 26 so as to achieve a density for expressing the flexibility of the roller base material 14 to be obtained. .

  After the foaming raw material M is completely foamed, the molding die 22 is opened after a certain curing period, and the retard roller 10 in which the core material 12, the roller base material 14, and the rubber ring 16 are integrated is removed. Manufacturing is completed by molding (see FIG. 4D). After that, it is shipped after carrying out post-processing such as polishing, inspection, etc. as necessary.

  In view of the above-mentioned problems inherent in the prior art described above, the present invention has been proposed to suitably solve this problem, and a roller base material that is a base material portion of a retard roller has a sufficient nip thickness. It is formed from a resin foam that can develop, and the outer peripheral surface of the roller that comes into contact with a printing medium such as paper to be retarded is formed from a rubber ring made of EPDM rubber having both a sufficient coefficient of friction and wear resistance. Thereby, the retard roller which can suppress the fall of a friction coefficient with time can be provided.

1 is a perspective view showing an overall configuration of a retard roller according to a preferred embodiment of the present invention. It is the state figure which showed a mode that the retard roller based on an Example retards printing media, such as paper. It is the schematic which shows the manufacturing apparatus which manufactures the retard roller which concerns on an Example suitably. It is a state figure which shows the mode of each step of retard roller manufacture using the manufacturing apparatus which concerns on FIG. It is the schematic which shows the whole structure of the retard roller which concerns on a prior art. It is the schematic which expands and shows the outer peripheral surface of the retard roller which concerns on a prior art. It is the state figure which showed a mode that the retard roller based on a prior art retarded printing media, such as paper.

Explanation of symbols

12 Core material 14 Roller base material 14a Outer peripheral surface 16 Rubber ring 18 Groove

Claims (5)

Core material (12) of the required length,
A roller base material (14) made of a resin foam having a three-dimensional network skeleton with the core material (12) in the center;
A retard roller comprising a rubber ring (16) made of EPDM rubber and covering an outer peripheral surface (14a) of the roller base material (14).   The retard roller according to claim 1, wherein the rubber ring (16) is formed with a plurality of grooves (18) having a required depth along the core member (12).   The retard roller according to claim 2, wherein a depth of the groove (18) is set to 0.1 to 1.5 mm.   The retard roller according to claim 2 or 3, wherein a depth of the groove (18) is formed along the core material (12). The retard roller according to any one of claims 1 to 4, wherein a tensile strength of the rubber ring (16) measured according to JIS K 6251 is set to 4 MPa or more.

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