WO2022114054A1

WO2022114054A1 - Paper feed roll

Info

Publication number: WO2022114054A1
Application number: PCT/JP2021/043163
Authority: WO
Inventors: 和志山口; 峻久小瀬
Original assignee: 住友理工株式会社
Priority date: 2020-11-27
Filing date: 2021-11-25
Publication date: 2022-06-02
Also published as: JP2022085076A

Abstract

Provided is a paper feed roll with excellent durability, which is less prone to paper transport failure due to accumulation of paper dust even after long-term use.　A paper feed roll comprising a shaft body and an elastic body layer 3 that is formed on the outer periphery of the shaft body, wherein protruding and recessed sections are formed on the peripheral surface 31 of the elastic body layer 3 by protrusions 4, and each of the protrusions 4 integrally has a first protruding structure 5 that protrudes from the peripheral surface 31 of the elastic body layer 3 and a second protruding structure 6 that protrudes in a needle shape from the surface 51 of the first protruding structure 5.

Description

Paper feed roll

The present invention relates to a paper feed roll that is suitably used in electrophotographic equipment such as copiers, printers, and facsimiles that employ an electrophotographic method.

The paper feed roll is formed in a cylindrical shape by, for example, an elastic material such as a rubber crosslinked body, and its peripheral surface serves as a contact surface with the paper. Paper dust generated from the paper may adhere to the peripheral surface of the paper feed roll. Then, during repeated contact with the paper, paper dust may accumulate on the peripheral surface of the paper feed roll. When paper dust accumulates on the peripheral surface of the paper feed roll, the contact area of the peripheral surface with respect to the paper decreases, and the friction coefficient of the contact surface with the paper decreases. As a result, poor paper transfer may occur.

It is known that the peripheral surface of the paper feed roll has irregularities in order to suppress paper transport defects. For example, Patent Document 1 describes that a plurality of axial grooves extending along the axial direction of a paper feed roller are provided in a predetermined shape and arrangement. Further, Patent Document 2 describes that in a paper feed roll in which an uneven portion having a corrugated cross-sectional shape is formed on an outer peripheral surface, a concave portion is formed along the axial direction of the roll. Patent Document 3 describes that convex portions and grooves are provided in a predetermined arrangement on the peripheral surface of the elastic body layer of the paper feed roll.

Japanese Unexamined Patent Publication No. 2014-055055 Japanese Unexamined Patent Publication No. 2006-143471 Japanese Unexamined Patent Publication No. 2019-043706

As in Patent Documents 1 to 3, by taking measures such as forming an uneven structure having a predetermined shape and arrangement on the surface of the paper feed roll, it is possible to suppress transport defects of the paper feed roll due to accumulation of paper dust on the peripheral surface. In addition, some effect is exhibited. However, it is desirable to more effectively suppress transport defects, assuming that the paper feed roll is used under conditions where the accumulation of paper dust is likely to proceed. For example, in recent years, low-quality paper such as inexpensive paper containing a large amount of ash and inferior paper containing a large amount of filler has become widespread. When paper containing a large amount of ash and filler is used, paper dust is generated during paper feeding and easily adheres to the surface of the paper feed roll. Then, the coefficient of friction between the paper feed roll and the paper is lowered, and the paper transport failure is likely to occur.

As described above, the adhesion of paper dust can be suppressed to some extent by forming an uneven shape on the surface of the paper feed roll, and further, as described in Patent Document 3, the uneven shape concave portion is used. Therefore, it is possible to suppress the retention of paper dust on the paper feed roll. However, when the paper dust generated at the contact portion between the paper and the convex portion of the paper feed roll is repeatedly applied to the convex portion and is repeatedly pressed against the convex portion, the contact portion is exposed to the paper dust. There is a possibility that the paper dust will firmly adhere and accumulate, and the effect of suppressing retention may not be sufficiently obtained. The sticking of the paper dust reduces the paper propulsion force when transporting the paper, which causes a defective transport of the paper and reduces the durability of the paper feed roll.

Therefore, the problem to be solved by the present invention is to provide a paper feed roll having excellent durability, in which paper transport defects due to accumulation of paper dust are unlikely to occur even after long-term use.

In order to solve the above problems, the paper feed roll according to the present invention includes a shaft body and an elastic body layer formed on the outer periphery of the shaft body, and the peripheral surface of the elastic body layer has a convex portion. Concavities and convexities are provided, and the convex portion integrally comprises a first convex structure protruding from the peripheral surface of the elastic body layer and a second convex structure protruding from the surface of the first convex structure in a needle shape. Have.

Here, it is preferable that the protruding height of the second convex structure from the surface of the first convex structure is equal to or higher than the protruding height of the first convex structure from the peripheral surface of the elastic body layer. The first convex structure includes a top, a top region where the second convex structure is formed on the surface, and a bottom where the second convex structure is not formed on the surface and is located on the bottom side of the top region. It is good to have a region. The protruding height of the first convex structure from the peripheral surface of the elastic layer is preferably 20 μm or more and 300 μm or less.

The second convex structure may have any of a columnar shape, a truncated cone shape, and a quadrangular pyramid shape. The diameter of the bottom of the second convex structure is smaller than the diameter of the bottom of the first convex structure, and is preferably 20 μm or more and 200 μm or less. The protruding height of the second convex structure from the surface of the first convex structure is preferably 50 μm or more and 300 μm or less.

The first convex structure may have at least one second convex structure on the surface. The convex portions may be arranged on the peripheral surface of the elastic body layer.

In the paper feed roll according to the present invention, the convex portion provided on the surface of the elastic body layer has a two-stage convex shape including a first convex structure and a second convex structure protruding from the surface of the first convex structure. Have. Of the two types of convex structure, the first convex structure is less likely to be deformed even when it comes into contact with the paper, and it has the role of ensuring a large paper propulsion force by generating a sliding force due to friction with the paper. Fulfill. On the other hand, the second convex structure formed as a needle-like protruding structure from the surface of the first convex structure is liable to be deformed by contact with paper. The second convex structure generates a paper propulsion force by the restoring force accompanying this deformation. The paper propulsion force due to the restoring force of this second convex structure is maintained even when paper dust is accumulated to some extent on the surface of the elastic body layer. In this way, the first convex structure and the second convex structure having different shapes show different contributions to the propulsion of the paper, so that the paper feed roll can be conveyed for a long period of time even in a situation where paper dust is likely to accumulate. It will be possible to continue using it with few defects.

Here, when the protruding height of the second convex structure from the surface of the first convex structure is equal to or higher than the protruding height of the first convex structure from the peripheral surface of the elastic body layer, the second convex structure is formed. Due to the contribution of the above, the effect of maintaining the paper propulsion force is particularly excellent even in a situation where paper dust is likely to accumulate.

The top region where the first convex structure includes the top and the second convex structure is formed on the surface, and the bottom region where the second convex structure is located on the bottom side of the top region and the second convex structure is not formed on the surface. If it has, the second convex structure will be formed in the region near the top of the first convex structure, and the second convex structure will easily contribute to the propulsion of the paper.

When the protrusion height of the first convex structure from the peripheral surface of the elastic body layer is 20 μm or more and 300 μm or less, the paper dust is less likely to stay on the surface of the convex portion, and the large paper due to the first convex structure. It becomes easier to generate propulsion.

When the second convex structure has a columnar shape, a truncated cone shape, or a quadrangular pyramid shape, the second convex structure has a simple shape, so that the second convex structure is formed. It is easy to form on the surface of a monoconvex structure. Further, the second convex structure tends to effectively contribute to the generation of the paper propulsive force due to the restoring force at the time of deformation and the maintenance of the paper propulsive force under the accumulation of paper dust.

When the diameter of the bottom of the second convex structure is smaller than the diameter of the bottom of the first convex structure and is 20 μm or more and 200 μm or less, and the protrusion height of the second convex structure from the surface of the first convex structure is When it is 50 μm or more and 300 μm or less, the second convex structure is highly effective in generating the paper propulsive force due to the restoring force at the time of deformation and maintaining the paper propulsive force under the accumulation of paper dust. Become.

When the first convex structure has at least one second convex structure on the surface, the contribution of the second convex structure for a long period of time is combined with the effect of generating a large paper propulsion force by the contribution of the first convex structure. The effect of maintaining the paper propulsion force when used can be obtained with high uniformity over the entire surface of the paper feed roll.

When the convex portions are arranged on the peripheral surface of the elastic body layer, a groove is formed between the rows formed by the arranged convex portions, and it becomes easy to remove the paper dust from the surface of the elastic body layer. ..

It is a schematic outside appearance of the paper feed roll which concerns on one Embodiment of this invention. The shape of the convex portion is simplified and displayed. It is sectional drawing which shows typically the structure near the surface of the elastic body layer of the said paper feed roll. (A) is a cross-sectional view including a plurality of convex portions, and (b) is a cross-sectional view showing one convex portion in an enlarged manner. It is a conceptual diagram explaining the contribution to the transport of the paper about (a) the first convex structure and (b) the second convex structure, respectively. It is a schematic diagram explaining the state of the surface of the paper feed roll. FIG.

Hereinafter, the paper feed roll according to the present invention will be described in detail with reference to the drawings.

<Outline of paper feed roll>
First, an outline of such a paper feed roll according to an embodiment of the present invention will be described. FIG. 1 is a schematic external view of a paper feed roll 1 according to an embodiment of the present invention.

The paper feed roll 1 according to the embodiment of the present invention includes a shaft body 2 and an elastic body layer 3 formed on the outer periphery of the shaft body 2. The elastic layer 3 is a layer (outermost layer) that appears on the surface of the paper feed roll 1. The elastic layer 3 has a tubular shape (cylindrical shape).

A plurality of convex portions 4 are provided on the peripheral surface 31 of the elastic body layer 3. The concave portions between the adjacent convex portions 4 are lower than the convex portions 4, and the convex portions 4 provide unevenness on the peripheral surface 31 of the elastic body layer 3. Each convex portion 4 has a two-stage convex structure in which a needle-shaped second convex structure 6 is formed on the surface of the first convex structure 5. The structure of the convex portion 4 will be described in detail later.

The arrangement of the convex portions 4 on the peripheral surface 31 of the elastic body layer 3, that is, the arrangement of the first convex structure 5 is not particularly limited, but in the form shown in FIG. 1, the plurality of convex portions 4 are the elastic body layer 3. It is regularly arranged in a staggered pattern on the peripheral surface 31. That is, the convex portions 4 are arranged in a row along the axial direction X of the paper feed roll 1, and the convex portions of the row adjacent to the convex portion 4 are arranged between the convex portions 4 and the convex portions 4 constituting a certain row. 4 are arranged, and the convex portions 4 are arranged alternately for each row along the axial direction X. The plurality of convex portions 4 are arranged on the peripheral surface 31 of the elastic body layer 3 in the axial direction X of the paper feed roll 1 and also in the direction at an angle of 45 ° with respect to the axial direction X of the paper feed roll 1. It will be done.

Note that the plurality of convex portions 4 may be arranged regularly, or may not be arranged regularly and may be randomly distributed. Further, when arranged regularly, the arrangement pattern is not limited to the staggered arrangement described above. When the convex portions 4 are arranged along the peripheral surface 31 of the elastic body layer 3, including the staggered arrangement, a groove is formed between the rows, which serves as an escape route for the generated paper dust. Easy to discharge. The convex portions 4 may be arranged in the circumferential direction along the peripheral surface 31 of the elastic body layer 3, or may be arranged in a direction different from the circumferential direction. The direction different from the circumferential direction means a form in which the elastic body layer 3 is arranged along the peripheral surface 31 of the elastic body layer 3 along a direction forming a predetermined angle with respect to the circumferential direction. Further, the convex portions 4 may be arranged spirally along the peripheral surface 31 of the elastic body layer 3.

The constituent materials of the shaft body 2 constituting the paper feed roll 1 include metal materials such as stainless steel, aluminum, and iron plated, polyacetal (POM), acrylonitrile butadiene styrene copolymer (ABS), and polycarbonate. A synthetic resin such as nylon can be used. The shaft body 2 may be a medium substance composed of these materials or a hollow body. If necessary, an adhesive, a primer, or the like may be applied onto the shaft body 2, and the adhesive, the primer, or the like may be made conductive as necessary.

The elastic body layer 3 is formed of an elastic material such as a crosslinked product of rubber. The material is not particularly limited as long as it is a rubber-like elastic material. For example, known rubber materials such as urethane rubber, hydrin rubber, silicone rubber, and ethylene / propylene / diene rubber (EPDM) can be used.

The elastic layer 3 may be non-conductive, conductive or semi-conductive. Specifically, the volume resistivity of the elastic body layer 3 is preferably in the range of 10 ² to 10 ¹⁵ Ω · cm, 10 ³ to 10 ¹⁴ Ω · cm, 10 ⁴ to 10 ¹³ Ω · cm. When the elastic body layer 3 has conductivity or semi-conductivity, it is easy to suppress the surface residual charge of the elastic body layer 3 to a low level and suppress the adhesion of paper dust.

When the elastic layer 3 has conductivity or semi-conductivity, the elastic layer 3 may contain a conductive agent from the viewpoint of reducing electrical resistance. Examples of the conductive agent include an electron conductive agent and an ionic conductive agent. Examples of the electronic conductive agent include carbon black, graphite, c-TiO ₂ , c-ZnO, c-SnO ₂ (c- means conductivity) and the like. Examples of the ionic conductive agent include a quaternary ammonium salt, a borate, and a surfactant.

Various additives may be appropriately added to the elastic layer 3 as needed. Additives include lubricants, vulcanization accelerators, anti-aging agents, light stabilizers, viscosity modifiers, processing aids, flame retardants, plasticizers, fillers, dispersants, defoamers, pigments, mold release agents, etc. Can be mentioned. The thickness of the elastic body layer 3 is not particularly limited, and may be appropriately set within the range of 0.1 to 10 mm or the like.

The elastic body layer 3 can be formed by using a rubber composition and molding with a molding die. For example, a cylindrical pin is arranged coaxially in the center of a hollow cylindrical roll molding die, and then an uncrosslinked rubber composition is injected into the space between the roll forming die and the pin. After heating and curing (crosslinking), the hollow tubular elastic body layer 3 can be formed by removing the mold and removing the pins. The convex portion 4 of the elastic body layer 3 can be formed, for example, by mold transfer using a molding die. As the molding die, a mold having a concave portion having a shape corresponding to the convex portion 4 formed on the inner peripheral surface thereof can be used. Further, the paper feed roll 1 is manufactured by press-fitting the separately prepared shaft body 2 into the hollow portion of the formed elastic body layer 3. When the shaft body 2 is made of a resin material such as POM, the shaft body 2 can also be manufactured by molding using a mold.

<Structure of convex part>
Next, in the paper feed roll 1 described above, the details of the structure of the convex portion 4 formed on the peripheral surface 31 of the elastic body layer 3 will be described. FIG. 2 shows a cross section in the vicinity of the peripheral surface of the elastic body layer 3 provided with the convex portion 4 as a schematic diagram. FIG. 2A displays a region including a plurality of convex portions 4, and FIG. 2B displays one convex portion 4 in an enlarged manner.

As shown in FIG. 2, each convex portion 4 has a two-stage convex structure. That is, the first convex structure 5 protruding from the peripheral surface 31 of the elastic body layer 3 and the second convex structure 6 protruding from the surface 51 of the first convex structure 5 are integrally provided. The second convex structure 6 projects like a needle from the surface 51 of the first convex structure 5. Here, the needle shape refers to a shape in which the protrusion height h is larger than the diameter r of the bottom portion 62 as the shape of the second convex structure 6. The bottom portion 62 of the second convex structure 6 refers to a portion where the second convex structure 6 is joined to the surface 51 of the first convex structure 5, and the diameter r of the bottom portion 62 is a circular approximation of the bottom portion 62. Refers to the diameter of the edge. The protruding height h of the second convex structure 6 refers to the height from the bottom 62 to the top 63 of the second convex structure 6.

The needle-shaped second convex structure 6 is preferably formed as a convex structure thinner than the first convex structure 5. That is, it is preferable that the area of the bottom portion 62 of the second convex structure 6 is smaller than the area of the bottom portion 52 of the first convex structure 5. The bottom portion 52 of the first convex structure 5 refers to a portion where the first convex structure 5 is joined to the peripheral surface 31 of the elastic body layer 3.

In the present embodiment, the convex portion 4 provided on the peripheral surface 31 of the elastic body layer 3 has a shape in which the needle-shaped second convex structure 6 protrudes from the surface 51 of the first convex structure 5. These two types of

convex structures

5 and 6 contribute to the propulsion of the paper in different forms when the paper feed roll 1 conveys the paper. FIG. 3A schematically shows the contribution of the first convex structure 5, and FIG. 3B schematically shows the contribution of the second convex structure 6. In FIGS. 3A and 3B, a virtual structure in which the first convex structure 5 and the second convex structure 6 are independently provided on the peripheral surface 31 of the elastic body layer 3 is displayed as a cross-sectional view, respectively. The elastic body layer 3 rotates in the rotation direction D1 and the paper P is conveyed in the transfer direction D2.

As shown in FIG. 3A, when the elastic body layer 3 rotates in a state where the paper P is in contact with the surface 51 of the first convex structure 5, the contact portion between the paper P and the first convex structure 5 is formed. Friction occurs, and a sliding force F1 is generated. This sliding force F1 is a propulsive force that causes the paper P to move in the transport direction D2 along the rotation direction D1 of the elastic body layer 3. Since the first convex structure 5 has a gently protruding shape, friction with the paper P becomes large, and a large propulsive force is generated. Since the first convex structure 5 has a gentle shape, even if the paper P is pressed against it, no significant deformation occurs. Therefore, the first convex structure 5 stably maintains a state in which a large propulsive force is applied by friction.

On the other hand, as shown in FIG. 3B, when the elastic body layer 3 rotates in a state where the paper P is in contact with the surface of the second convex structure 6, the second convex structure 6 is an elastic body from the paper P. It receives a force in the direction of being pressed toward the peripheral surface 31 of the layer 3. Since the second convex structure 6 has a needle-like thin shape, it is easily deformed and curved in the middle of the protruding direction when it receives such a force. When such a deformation occurs, a restoring force F2 in the direction of eliminating the deformation acts on the second convex structure 6. Since the deformation of the second convex structure 6 occurs in the direction opposite to the rotation direction D1 of the elastic body layer 3 in the direction in which the top 63 side of the needle shape tilts, the restoring force F2 is along the rotation direction D1 of the elastic body layer 3. Will have ingredients. The component of the restoring force F2 along the rotation direction D1 becomes a propulsive force for moving the paper P in the transport direction D2.

Since the contact area of the second convex structure 6 with the paper P is smaller than that of the first convex structure 5, the magnitude of the propulsive force given by the second convex structure 6 to the paper P is given by the first convex structure 5. It is smaller than the propulsion force. However, the propulsive force due to the first convex structure 5 is mainly due to the sliding force F1 due to the friction between the first convex structure 5 and the paper P, and the paper dust adheres to the top 53 of the first convex structure 5. Then, the coefficient of friction may decrease and the sliding force F1 may also decrease, whereas the propulsive force due to the second convex structure 6 has a small contribution of friction and is centered on the contribution of the restoring force F2 due to deformation. It is substantially unaffected by the state of the surface of the convex portion 4. Therefore, even if paper dust is accumulated to some extent on the peripheral surface 31 of the elastic body layer 3 and the surface of the convex portion 4, the propulsive force due to the second convex structure 6 is unlikely to decrease. That is, even if the paper feed roll 1 is used for a long period of time and the accumulation of paper dust cannot be avoided, the propulsive force due to the second convex structure 6 is maintained for a long period of time. As described above, although the first convex structure 5 may cause a decrease due to the adhesion of paper dust, it generates a large propulsive force as an absolute value, and the second convex structure 6 has a small absolute value. , It will generate a propulsive force that is not easily affected by the adhesion of paper dust.

The convex portion 4 provided on the peripheral surface 31 of the elastic body layer 3 of the paper feed roll 1 according to the present embodiment has a shape in which the first convex structure 5 and the second convex structure 6 are combined. As described above, the first convex structure 5 and the second convex structure 6 give different paper propulsion forces in terms of origin and characteristics. Therefore, in the paper feed roll 1 according to the present embodiment, when the paper P is conveyed, the propulsive force due to the first convex structure 5 and the propulsive force due to the second convex structure 6 are generated in a complex manner, and each of them is propelled. The characteristics of the force are exhibited together. FIG. 4 schematically shows the shape of the convex portion 4 of the paper feed roll 1 of the present embodiment in which the first convex structure 5 and the second convex structure 6 are combined. This corresponds to the cross-sectional view shown in FIG. 2, but the number of the second convex structure 6 provided in each first convex structure 5 is only one, and the display is simplified. FIG. 4A shows a state in which the paper P is not brought into contact with the convex portion 4, and FIG. 4B shows a state in which the paper P is brought into contact with the convex portion 4 to convey the paper P.

In the state where the paper P is not in contact with the convex portion 4, as shown in FIG. 4A, the needle-shaped second convex structure 6 stands up from the surface 51 of the first convex structure 5. .. As shown in FIG. 4B, when the paper P is brought into contact with the surface of the elastic body layer 3 having the convex portion 4 and the elastic body layer 3 is rotated in the rotation direction D1, the circumference of the elastic body layer 3 is increased from the paper P. A force that presses the second convex structure 6 toward the surface 31 acts. Then, the second convex structure 6 is deformed so as to tilt in the direction opposite to the rotation direction D1 of the elastic body layer 3. On the other hand, the first convex structure 5 hardly deforms. When the second convex structure 6 is tilted, the surface 51 of the first convex structure 5 comes into contact with the paper P either directly or via the collapsed thin second convex structure 6. Then, similar to the situation of FIG. 3A, a sliding force F1 due to friction is generated between the first convex structure 5 and the paper P along the rotation direction D1 of the elastic body layer 3. On the other hand, a restoring force F2 that tries to return to the original upright state acts on the deformed second convex structure 6. This restoring force F2 has a component along the rotation direction D1 of the elastic body layer 3. In this way, both the propulsive force caused by the sliding force F1 due to the first convex structure 5 and the propulsive force caused by the restoring force F2 of the second convex structure 6 work along the rotation direction D1 of the elastic body layer 3. .. The sum of these two types of propulsive force acts as a propulsive force for the paper P, and the paper P is moved in the transport direction D2.

Since the propulsive force due to the first convex structure 5 is larger in absolute value than the propulsive force due to the second convex structure 6, it is mainly the first convex structure 5 that contributes to strongly transporting the paper P. be. However, when the paper feed roll 1 is used for a long period of time and the paper dust adheres to the surface of the convex portion 4, the coefficient of friction between the first convex structure 5 and the paper P decreases, which is due to the contribution of the first convex structure 5. Propulsion may be reduced. In particular, in a situation where paper dust adheres to the surface of the convex portion 4 and easily accumulates, such as when using low-quality paper, the accumulated paper dust receives a force in the direction of being pressed from the paper P to the convex portion 4. In the meantime, it may be firmly fixed to the surface of the convex portion 4. Then, there is a possibility that the propulsive force is significantly reduced due to the contribution of the first convex structure 5.

On the other hand, regarding the propulsive force due to the second convex structure 6, the contribution of friction with the paper P is small, and the contribution of the restoring force F2 due to the physical deformation of the second convex structure 6 itself is dominant. This deformation and the generation of the restoring force F2 accompanying it are due to the fact that the second convex structure 6 has a needle-like shape, and is almost dependent on the surface condition of the second convex structure 6 such as the adhesion of paper dust. do not do. Therefore, even if the accumulation of paper dust and the fixing progress to some extent, the propulsive force due to the second convex structure 6 is unlikely to decrease. As described above, the convex portion 4 has a two-stage shape in which the first convex structure 5 and the second convex structure 6 are combined, so that the large propulsive force due to the first convex structure 5 and the second convex structure can be obtained. Both long-term sustainable propulsion by 6 can be used, and for paper P from the initial stage where paper dust does not accumulate to the stage where paper dust accumulates and sticks after long-term use. It can exert a stable propulsion force. As a result, the paper feed roll 1 is less likely to cause paper transport defects for a long period of time and has high durability.

As described with reference to FIG. 3A, if only the first convex structure 5 is provided on the peripheral surface 31 of the elastic body layer 3, in the initial stage where the adhesion of paper dust has not progressed, the sliding due to friction A high paper propulsion force is given by the power F1, and the paper feed roll 1 exhibits good paper transportability. However, as the accumulation of paper dust progresses, the friction coefficient of the surface is lowered, so that poor transport of the paper P is likely to occur, and high durability cannot be obtained. On the other hand, as described with reference to FIG. 3B, if the first convex structure 5 is not provided and the second convex structure 6 is formed directly on the peripheral surface 31 of the elastic body layer 3, the contribution of friction is small. Since the contribution of the restoring force F2 becomes dominant and the propulsive force is generated, a large propulsive force cannot be obtained from the initial stage, and the paper transportability is lowered. Even if the accumulation of paper dust progresses, it is unlikely that the propulsive force will be significantly reduced from the initial state, but since the paper transportability is already low from the initial state, the paper transportability is slightly reduced due to the accumulation of paper dust. Even with this alone, there is a possibility that sufficient paper transportability cannot be obtained, and it cannot be said that the durability is high. As described above, neither the first convex structure 5 nor the second convex structure 6 gives high durability by itself. However, as described above based on FIG. 4, the paper feed roll 1 according to the present embodiment provided with the convex portion 4 in which the first convex structure 5 and the second convex structure 6 are combined has the first convex structure. The characteristics of both 5 and the second convex structure 6 are combined to obtain high durability.

The specific shapes and dimensions of the first convex structure 5 and the second convex structure 6 are not particularly limited, but the following forms can be exemplified as preferable ones. Hereinafter, parameters related to dimensions such as the height and diameter of the first convex structure 5 and the second convex structure 6 may be evaluated as average values for a plurality of convex structures. For example, it may be evaluated as an average value for 10 randomly selected convex structures. Further, as the diameter of each part, the diameter when the part is approximated to a circle may be used.

Examples of the shape of the first convex structure 5 include a hemisphere and other partial spheres, an amorphous shape, a prism, a cone, a sphere segment, and a wedge shape. Examples of the pillar include a cylinder, an elliptical pillar, a prism (square pillar, pentagonal pillar, etc.), a fan-shaped pillar, a D-shaped pillar, a gear-shaped pillar, and the like. Further, the head of the pillar may be a head pillar having a shape cut out in a slanted shape or a curved shape (a head cylinder, a head prism, etc.). Examples of the pyramid include a cone, an elliptical pyramid, and a pyramid (square pyramid, pentagonal pyramid, etc.). In addition, a frustum (a cone, a pyramid, etc.) whose head is cut into a plane, a slope, or a curved shape; if the head is a plane, a frustum ) May be. A spherical segment is a solid shaped like a sphere cut out by two parallel planes. The "sphere" includes not only a true sphere but also an ellipsoidal sphere.

The first convex structure 5 is joined to the peripheral surface 31 of the elastic body layer 3 in a large area from the viewpoint of facilitating stable and large propulsive force during paper transport, and gently protrudes with respect to the peripheral surface 31. It is preferable to take a shape. For example, in the first convex structure 5, it is preferable that the area of the cross section parallel to the bottom portion 52 is the largest at the bottom portion 52 and monotonically decreases toward the top portion 53 along the height direction. As the shape of such a first convex structure 5, among those listed above, a partial sphere including a hemisphere, a spherical segment, and the like can be exemplified. A spherical segment shape is particularly preferable. Further, the diameter of the bottom portion 52 of the first convex structure 5 is R, the protrusion height of the first convex structure 5 from the peripheral surface 31 of the elastic body layer 3 is H, and the protrusion ratio H / R is 1 or less, and further 1 It is preferable to take a shape of / 2 or less and 1/3 or less. In this way, the first convex structure 5 is joined to the peripheral surface 31 of the elastic body layer 3 in a large area and has a shape that gently protrudes from the peripheral surface 31, so that the paper P can be conveyed. A large amount of friction is generated with the paper P, and the deformation of the first convex structure 5 is suppressed to a small extent. As a result, the role of the first convex structure 5 in generating a large propulsive force is greatly exerted.

The protruding height H of the first convex structure 5 from the peripheral surface 31 of the elastic body layer 3 is preferably 50 μm or more, more preferably 80 μm or more, and 100 μm or more. Then, the effect of discharging the paper dust to the concave portion between the convex portions 4 without retaining the paper dust on the surface of the elastic body layer 3 is excellent. On the other hand, the protruding height H of the first convex structure 5 is preferably 300 μm or less, more preferably 150 μm or less. Then, it becomes easy to remove the paper dust from the surface 51 of the first convex structure 5, and it becomes easy to suppress the deformation of the first convex structure 5 at the time of paper transport to be small and to generate a large sliding force F1 by friction.

The diameter R of the bottom portion 52 of the first convex structure 5 is preferably 200 μm or more and 400 μm or less. As a result, it is possible to stably generate a large paper propulsion force due to the contribution of the first convex structure 5 when the paper is conveyed. Further, when the first convex structure 5 has a shape such as a spherical segment having a plane on the top 53, the diameter R'of the surface of the top 53 may be smaller than the diameter R of the bottom 52. Further, the diameter R'of the top 53 is preferably 100 μm or more and preferably 300 μm or less. Then, a large paper propulsion force due to the contribution of the first convex structure 5 is likely to be stably generated, and the second convex structure 6 is a structure of the convex portion 4 provided at or near the top 53 of the first convex structure 5. Can be stably formed and held.

The shape of the second convex structure 6 is not particularly limited as long as it is needle-shaped, that is, the shape in which the protrusion height h from the surface 51 of the first convex structure 5 is larger than the diameter r of the bottom portion 62. , Pillars, cones, wedges, etc. Examples of the pillar include a cylinder, an elliptical pillar, a prism (square pillar, pentagonal pillar, etc.), a fan-shaped pillar, a D-shaped pillar, a gear-shaped pillar, and the like. Further, the head of the pillar may be a head pillar having a shape cut out in a slanted shape or a curved shape (a head cylinder, a head prism, etc.). Examples of the pyramid include a cone, an elliptical pyramid, and a pyramid (square pyramid, pentagonal pyramid, etc.). In addition, a frustum (a cone, a pyramid, etc.) whose head is cut into a plane, a slope, or a curved shape; if the head is a plane, a frustum ) May be. As in each of the shapes listed here, the elastic body layer 3 having the convex portion 4 in which the first convex structure 5 and the second convex structure 6 are combined is formed by taking a simple shape of the second convex structure 6. Easy to form. Further, when the paper is conveyed, the second convex structure 6 is likely to be deformed and the restoring force F2 is likely to be generated accordingly. It is also excellent in the effect of maintaining the shape of the convex portion 4 on which the second convex structure 6 is formed for a long period of time. When the second convex structure 6 has any one of a columnar structure, a truncated cone shape, and a quadrangular pyramid shape, each of these effects is particularly excellent.

The protruding height h of the second convex structure 6 is not particularly limited as long as it is larger than the diameter r of the bottom 62 of the second convex structure 6 (h> r), but is not particularly limited, but is equal to or higher than the protruding height H of the first convex structure 5. It is preferable that (h ≧ H). Further, it is preferable that the protruding height h of the second convex structure 6 is larger than the protruding height H of the first convex structure 5 (h> H). Further, the protruding height h of the second convex structure 6 is preferably 50 μm or more, more preferably 100 μm or more. As in these cases, the second convex structure 6 has a sufficiently large protrusion height h, so that the restoring force F2 is generated due to the deformation of the second convex structure 6 to maintain the paper propulsion force for a long period of time. Excellent effect.

On the other hand, the protruding height h of the second convex structure 6 is preferably 3 times or less the protruding height H of the first convex structure 5 (h ≦ 3H). Further, the protruding height h of the second convex structure 6 is preferably 300 μm or less, more preferably 200 μm or less. In this way, by keeping the protruding height h of the second convex structure 6 within a range that does not become too large, the restoring force F2 accompanying the deformation of the second convex structure 6 makes it easier to generate a paper propulsive force. It is also excellent in the convenience of forming the convex portion 4 on which the second convex structure 6 is formed and the stability of shape retention.

It is preferable that the area and diameter r of the bottom portion 62 of the second convex structure 6 are smaller than the area and diameter R of the bottom portion 52 of the first convex structure 5. Then, the effect of maintaining the paper propulsion force for a long period of time is excellent due to the generation of the restoring force F2 accompanying the deformation of the second convex structure 6. In addition, when the first convex structure 5 has a shape having a plane on the top 53 such as a spherical segment, the area and diameter r of the bottom 62 of the second convex structure 6 is the top 53 of the first convex structure 5. Area and diameter R'should be smaller than. Further, the diameter r of the bottom portion 62 of the second convex structure 6 is ½ or less (r ≦ R ′ / 2) of the diameter R ′ of the top 53 of the first convex structure 5 and 1/4 or less (r ≦ R ≦ R). '4) is good. Further, the diameter r of the bottom portion 62 of the second convex structure 6 is preferably 200 μm or less, more preferably 100 μm or less. On the other hand, if the diameter r of the bottom portion 62 of the second convex structure 6 is set to 10 μm or more, further 20 μm or more, it becomes easy to generate a paper propulsive force due to the restoration accompanying the deformation of the second convex structure 6, and the second It is also excellent in the convenience of forming the convex portion 4 in which the convex structure 6 is formed and the stability of shape retention.

The number of second convex structures 6 provided per one first convex structure 5 is not particularly limited. However, from the viewpoint of high uniformity in each part of the paper feed roll 1, generation of propulsive force due to the contribution of the second convex structure 6 and enhancement of durability, at least one second in each first convex structure 5. It is preferable to provide the convex structure 6. Further, from the viewpoint of enhancing the contribution of the second convex structure 6, it is preferable to provide two or more second convex structures 6 per one first convex structure 5. On the other hand, from the viewpoint of suppressing the structure of the convex portion 4 from becoming excessively complicated, it is preferable to keep the number of the second convex structures 6 provided in one first convex structure 5 to 5 or less. ..

The position where the second convex structure 6 is provided on the surface 51 of the first convex structure 5 is not particularly limited, but the second convex structure 6 is provided at or near the top 53 of the first convex structure 5. The second convex structure 6 is more likely to contribute to the transportation of the paper P. Preferably, the first convex structure 5 is present on the surface of the top region 54 when the first convex structure 5 is virtually divided into a top region 54 including the top 53 and a bottom region 55 located closer to the bottom 52 than the top region 54. It is preferable that the number of the second convex structures 6 to be formed is larger than the number of the second convex structures 6 present on the surface of the bottom region 55. Further, it is preferable that the second convex structure 6 is formed only on the surface of the top region 54, and the second convex structure 6 is not formed on the surface of the bottom region 55. In other words, the second convex structure 6 is concentrated in the top 53 of the first convex structure 5 and its vicinity, and the top region 54 in which the second convex structure 6 is formed and the second convex structure 6 are not formed. It is preferable that the first convex structure 5 can be virtually divided into the bottom region 55. When the first convex structure 5 has a top portion 53 on a plane such as a spherical segment, it is more preferable that the second convex structure 6 is formed only on the surface of the top portion 53. The second convex structure 6 corresponds to the bottom region 55 of the first convex structure 5 and the peripheral surface 31 of the elastic body layer 3 where the first convex structure 5 is not formed, that is, the concave portion of the surface unevenness. Although it does not prevent it from being formed at the locations, the second convex structure 6 formed at those locations has almost no effect on the generation of paper propulsion force and the improvement of durability.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. The present invention is not limited to the following examples.

<Preparation of sample>
A pin is placed in the center of a cylindrical molding die having a concave portion having a predetermined shape and arrangement on the inner peripheral surface, and the urethane rubber composition is injected into the space between the die and the pin, and then demolding and demolding. By removing the pins, a hollow cylindrical elastic body layer having a convex portion on the surface was formed. Then, the core material obtained by molding the POM into a hollow cylinder was press-fitted into the hollow portion of the elastic body layer to obtain a paper feed roll. The elastic layer has an outer diameter of φ20 mm, an inner diameter of φ10 mm, and a length of 30 mm. The core material had an outer diameter of φ10 mm, an inner diameter of φ6 mm, and a total length of 45 mm. In each sample, the arrangement, shape, and dimensions of the convex portions were as shown in Tables 1 and 2. The number densities of the protrusions on the surface of the elastic layer are the same for each sample.

<Evaluation of durability performance>
The durability performance was evaluated using the prepared paper feed roll. The produced paper feed roll was incorporated into a commercially available copying machine equipped with an FRR type paper feed system, and the paper feed performance was evaluated. Commercially available PPC paper was used as the paper, 600,000 sheets were passed, and the number of paper jams was measured. "A" is for paper jams that occur 0 times, "B" is for paper jams that occur 1 to 3 times, and "B" is for paper jams that occur 4 to 6 times. "C", the number of paper jams occurring 7 to 10 times was "D", and the number of paper jams occurring 11 times or more was "E". When the evaluation results are A, B, and C, it can be determined that the durability is sufficiently high, and when the evaluation results are D and E, it is determined that the durability is low.

<Evaluation result>
Tables 1 and 2 show the structure (shape, arrangement, dimensions of each part) of the convex portion formed on the paper feed roll of each sample, and the evaluation result of durability performance. As each dimensional value, the average value for 10 randomly selected convex portions is displayed. When the second convex structure is formed as a quadrangular pyramid, the length of the side of the square is described in the columns of the diameters r and r'of the bottom and the top.

In Examples 1 to 13 shown in Tables 1 and 2, in each case, the convex portion formed on the elastic body layer of the paper feed roll has a two-stage shape in which the surface of the first convex structure is combined with the second convex structure. I'm taking. Correspondingly, high durability performance evaluated as A to C is obtained. On the other hand, in Comparative Examples 1 and 2 in which the convex portion has only the first convex structure and the surface thereof does not have the second convex structure, only the low durability performance evaluated as D is obtained. In Comparative Examples 3 to 5 in which the needle-shaped structure regarded as the second convex structure is directly formed on the peripheral surface of the elastic body layer, only the durability performance evaluated as lower E is obtained.

In each of Examples 1 to 8, a truncated cone-shaped second convex structure is arranged on the surface of a randomly arranged amorphous first convex structure. Among them, Example 1 In, a particularly high durability performance of A evaluation is obtained. In the first embodiment, the protruding height H of the first convex structure, the protruding height h of the second convex structure, and the diameter r of the bottom are intermediate in the range adopted in the first to eighth embodiments. It takes a value. In addition, the number of second convex structures per first convex structure is as large as three. It is considered that having these configurations leads to particularly high durability.

Further, Examples 10 to 13 are different from Example 1 in at least one of the shape, arrangement, and shape of the second convex structure of the first convex structure, but in any of the first to ten examples, Examples. Similar to No. 1, a particularly high durability performance of A evaluation is obtained. From this, it is possible to form a convex portion having a two-stage shape having a first convex structure and a second convex structure regardless of the shapes of the first convex structure and the second convex structure and the arrangement of the first convex structure. It can be said that the effect of improving durability can be obtained.

Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the above embodiments and examples, and various modifications can be made without departing from the spirit of the present invention. ..

Claims

A shaft body and an elastic body layer formed on the outer periphery of the shaft body are provided.
The peripheral surface of the elastic layer is provided with irregularities due to convex portions.
The convex part is
The first convex structure protruding from the peripheral surface of the elastic layer and
A paper feed roll integrally having a second convex structure protruding from the surface of the first convex structure in a needle shape.
The first aspect of the present invention, wherein the protruding height of the second convex structure from the surface of the first convex structure is equal to or higher than the protruding height of the first convex structure from the peripheral surface of the elastic body layer. Paper feed roll.
The first convex structure is
Including the apex, the apex region where the second convex structure is formed on the surface, and
The paper feed roll according to claim 1 or 2, which is located on the bottom side of the top region and has a bottom region in which the second convex structure is not formed on the surface.
The paper feed roll according to any one of claims 1 to 3, wherein the protrusion height of the first convex structure from the peripheral surface of the elastic body layer is 20 μm or more and 300 μm or less.
The paper feed roll according to any one of claims 1 to 4, wherein the second convex structure has a columnar shape, a truncated cone shape, or a quadrangular pyramid shape.
The paper feed according to any one of claims 1 to 5, wherein the diameter of the bottom of the second convex structure is smaller than the diameter of the bottom of the first convex structure, and is 20 μm or more and 200 μm or less. roll.
The paper feed roll according to any one of claims 1 to 6, wherein the protrusion height of the second convex structure from the surface of the first convex structure is 50 μm or more and 300 μm or less.
The paper feed roll according to any one of claims 1 to 7, wherein the first convex structure has at least one second convex structure on the surface.
The paper feed roll according to any one of claims 1 to 8, wherein the convex portion is arranged on the peripheral surface of the elastic body layer.