WO2021029300A1

WO2021029300A1 - Method for manufacturing conveyance roller, conveyance roller, and electrophotography image forming apparatus

Info

Publication number: WO2021029300A1
Application number: PCT/JP2020/030046
Authority: WO
Inventors: 大阿久津; 基森; 賀文今津
Original assignee: コニカミノルタ株式会社
Priority date: 2019-08-09
Filing date: 2020-08-05
Publication date: 2021-02-18
Also published as: JPWO2021029300A1

Abstract

The present invention addresses the problem of providing a method for manufacturing a conveyance roller that is inexpensive and has high shape accuracy, a conveyance roller, and an electrophotography image forming apparatus provided with the conveyance roller. The method for manufacturing a conveyance roller according to the present invention has a resinous shaft part and a resinous tube part, the method characterized by comprising: a step of setting the resinous tube part in a mold and filling a melted molding resin in the tube to mold the resinous shaft part.

Description

Manufacturing method of transport roller, transport roller and electrophotographic image forming apparatus

The present invention relates to a method for manufacturing a transport roller, a transport roller, and an electrophotographic image forming apparatus. More specifically, the present invention relates to a method for manufacturing a transport roller, which is inexpensive and has high shape accuracy, a transport roller, and an electrophotographic image forming apparatus.

Rollers for transport used in transport units such as laser beam printers and multifunction devices are rollers that have an elastic body for gripping objects to be transported such as paper, and "rollers" that move with the rollers. It is configured to have a so-called resin roller.

FIG. 1 is an example of a schematic diagram of a roller used in a transport unit. The roller 1 used in the transfer unit has a transfer roller 2 and a resin roller 6. The transport roller 2 has an elastic body portion 4 and a gear portion 5 on the shaft 3 and functions as a drive roller. A resin roller 6 that is in contact with the elastic body portion 4 and is driven by its rotation is provided as a roller. The resin roller 6 has a groove shape (also referred to as “edge groove”) 7 on the outer peripheral surface. The transport roller 1 transports paper by sandwiching, for example, paper, which is an object to be transported, between the elastic body portion 4 and the resin roller 6 and rotationally driving the paper in that state.

The elastic body portion 4 uses an elastic body such as rubber in order to stably convey the paper in contact with the paper or the like to be conveyed. Further, from the viewpoint of slidability, the resin roller 6 uses polyoxymethylene resin (hereinafter abbreviated as “POM”, also referred to as polyacetal), and is often manufactured at low cost by injection molding.

However, since the melting point of toner used for printing, for example, toner containing styrene acrylic and polyester resin, is about 100 ° C., the elastic body part of the transport roller or the resin roller that comes into contact with the paper sent in a warm state after fixing. There was a problem that toner adhered to the surface portion of the roller.

In order to avoid this problem, a method of assembling a heat-shrinkable tube of perfluoroelastomer (PFE) on the roller surface has been proposed, but when this is applied to a resin roller, it is not possible to make a protrusion groove, so paper. There was a concern that a feeding problem would occur, and there was a problem that it took a lot of man-hours to assemble.

Another method is to mold the resin roller itself with a fluororesin such as ethylene-tetrafluoroethylene (ETFE) or perfluoroalkoxy alkane resin (PFA), which has high antifouling properties, and combine the shaft part with a metal or the like. However, this also has the problem that the material cost is high and the problem that abnormal noise is generated due to wear with metal.
Further, although the resin roller can be manufactured inexpensively and efficiently by injection molding, the injection molded product generally has a drawback that the shape accuracy is inferior to that of the cut product. This is often a serious problem, especially when it comes to roundness (the magnitude of deviation from a geometrically correct circle: the deviation of each diameter of a circle of constant cross section). As a countermeasure against this, Patent Document 1 discloses a technique for forming a groove structure in an injection molding die. However, such a technique for integrally molding is insufficient from the viewpoint of shape accuracy of the molded product, and further improvement in accuracy has been required.

Special Fair 07-053393

The present invention has been made in view of the above problems and situations, and the problem to be solved thereof is an inexpensive method for manufacturing a transport roller having high shape accuracy, a transport roller, and an electrophotographic image forming apparatus including the same. Is to provide.

In the process of examining the cause of the above problem in order to solve the above problems, the present inventor has a resin tube portion and a resin shaft portion having a structure in which the transport roller is insert-molded into the tube portion. By providing, the resin tube portion can be used on the outer surface side, and the shape change of the tube portion due to the influence of the shrinkage of the shaft portion during insert molding can be reduced, so that the cost is low. We have found that a transport roller with high shape accuracy can be realized, and have arrived at the present invention.
That is, the above problem according to the present invention is solved by the following means.

1. A method for manufacturing a transport roller having a resin shaft portion and a resin tube portion, wherein the tube portion is set in a mold, and further, the molten molding resin is filled in the tube portion. A method for manufacturing a transport roller, which comprises a step of forming a shaft portion.

2. The tube portion and the shaft portion are held by the shrinkage force of the molding resin at the time of cooling by filling both end surfaces of the tube portion with the molten molding resin and then cooling the tube portion. The method for manufacturing a transport roller according to the first item.

3. The method for manufacturing a transport roller according to

item

1 or 2, wherein the Young's modulus of the resin constituting the tube portion at 25 ° C. is 100 MPa or more.

4. The method for manufacturing a transport roller according to any one of items 1 to 3, wherein both end faces of the tube portion are in contact with the resin portion constituting the shaft portion.

5. The method for manufacturing a transport roller according to item 4, wherein the outer peripheral surface of the resin portion has a groove shape.

6. The following formula (1) is satisfied by controlling the molding shrinkage force P, the area A of the portion where the resin portion contacts both end surfaces of the tube portion, and the Young's modulus E of the resin constituting the tube portion. The method for manufacturing a transport roller according to

item

4 or 5.
Equation (1)
ε = P / AE <0.17
(In the formula (1), ε represents the strain of the tube portion due to molding. P represents the molding shrinkage force represented by the following formula (2). A represents the resin portion in contact with both end surfaces of the tube portion. Represents the area of the portion. E represents the Young's modulus of the resin constituting the tube portion at 25 ° C.)
Equation (2)
P = Young's modulus of the resin constituting the shaft at 25 ° C. × Cross-sectional area of the resin constituting the shaft × (Shaft molding shrinkage-Tube shrinkage)

7. The method for manufacturing a transport roller according to any one of items 1 to 6, wherein the water repellency angle of the tube portion at 25 ° C. is 90 ° or more.

8. The method for manufacturing a transport roller according to any one of items 1 to 7, wherein a polyolefin resin is used as a constituent material for the tube portion.

9. The method for manufacturing a transport roller according to any one of items 1 to 8, wherein polypropylene is used as a constituent material for the tube portion and polyacetal is used for the shaft portion.

10. A transport roller that transports the object to be transported.
A transport roller, characterized in that the transport roller includes a resin tube portion and a resin shaft portion having a structure in which the tube portion is insert-molded.

11. The transport roller according to Item 10, wherein the Young's modulus of the resin constituting the tube portion at 25 ° C. is 100 MPa or more.

12. The transport roller according to

item

10 or 11, wherein the resin portions constituting the shaft portion are in contact with both end surfaces of the tube portion.

13. The transport roller according to Item 12, wherein the transport roller satisfies the following formula (1).
Equation (1)
ε = P / AE <0.17
(In the formula (1), ε represents the strain of the tube portion due to molding. P represents the molding shrinkage force represented by the following formula (2). A represents the resin portion in contact with both end surfaces of the tube portion. Represents the area of the portion. E represents the Young's modulus of the resin constituting the tube portion at 25 ° C.)
Equation (2)
P = Young's modulus of the resin constituting the shaft at 25 ° C. × Cross-sectional area of the resin constituting the shaft × (Shaft molding shrinkage-Tube shrinkage)

14. An electrophotographic image forming apparatus comprising the transport roller according to any one of items 10 to 13.

According to the above means of the present invention, it is possible to provide an inexpensive method for manufacturing a transport roller with high shape accuracy, a transport roller, and an electrophotographic image forming apparatus including the same.
Although the mechanism of expression or mechanism of action of the effect of the present invention has not been clarified, it is inferred as follows.

The transport roller is provided with a resin tube portion and a resin shaft portion having a structure in which the tube portion is insert-molded, and the resin tube portion can be used on the outer surface side and is insert-molded. Since it is possible to reduce the shape change of the tube portion due to the influence of the contraction of the shaft portion at the time, it is presumed that an inexpensive and highly accurate transfer roller can be realized. Further, since the material constituting the shaft portion and the tube portion mainly on the outer surface of the transport roller can be made of different materials, it is possible to obtain a highly functional transport roller.

An example of a schematic diagram of a roller used in a transport unit An example of a cross-sectional view of a transport roller of the present invention An example of an external perspective view of a transport roller of the present invention Schematic diagram illustrating the outline of the abrasion resistance test Schematic diagram illustrating the outline of the abrasion resistance test Schematic diagram for explaining the adhesion between the shaft and the tube Schematic diagram explaining a method of measuring adhesion Schematic diagram explaining a method of measuring adhesion An example of a diagram showing the relationship between theoretical adhesion and measured adhesion Schematic diagram explaining the deformation of the tube portion Schematic diagram illustrating a method for measuring roundness Schematic diagram illustrating a method for measuring roundness Cross-sectional view of an example of an insert-molded transport roller (resin roller) The figure explaining insert molding The figure explaining insert molding The figure explaining insert molding The figure explaining insert molding The figure explaining insert molding The figure explaining insert molding An example of a diagram showing the relationship between ε and roundness

The method for manufacturing a transport roller of the present invention is a method for manufacturing a transport roller having a resin shaft portion and a resin tube portion, wherein the tube portion is set in a mold and further melted for molding. It is characterized by having a step of filling the tube portion with a resin and molding the shaft portion. This feature is a technical feature common to or corresponding to each of the following embodiments (forms).

In an embodiment of the present invention, both end faces of the tube portion are filled with the molten molding resin and then cooled, and the shrinking force of the molding resin during cooling causes the tube portion and the shaft portion to be cooled. It is preferable to hold the above because the adhesion between the shaft portion and the tube portion is enhanced and slipping prevention can be obtained.
In an embodiment of the present invention, from the viewpoint of suppressing deformation of the tube portion, it is preferable that the Young's modulus of the resin constituting the tube portion at 25 ° C. is 100 MPa or more.

Further, by making both end surfaces of the tube portion in contact with the resin portion constituting the shaft portion, the resin portion holds the tube portion due to the contraction of the shaft portion during the insert molding, and the tube portion This is preferable because it has the effect of suppressing idling with respect to the shaft portion.
Further, in the present invention, it is preferable that the outer peripheral surface of the resin portion has a groove shape. As a result, the effect of hooking the end portion of the paper that could not be completely discharged at the time of paper ejection with the groove and feeding the paper can be obtained.
Further, from the viewpoint of exhibiting the effect of the present invention, the above formula is controlled by controlling the molding shrinkage force P, the area A of the portion where the resin portion contacts both end surfaces of the tube portion in the previous period, and the Young's modulus E of the resin constituting the tube portion. It is preferable to satisfy (1).

Further, it is preferable that the water repellency angle of the tube portion at 25 ° C. is 90 ° or more because the printing toner is prevented from adhering and the effect of suppressing the retransfer to the paper can be obtained.
Further, in the present invention, it is preferable to use a polyolefin resin as a constituent material for the tube portion. As a result, since the polyolefin-based resin has a large water-repellent angle, the effect of preventing toner adhesion can be obtained.
In an embodiment of the present invention, it is preferable to use polypropylene as a constituent material for the tube portion and polyacetal for the shaft portion.

Further, it is a transport roller for transporting an object to be transported, wherein the transport roller includes a resin tube portion and a resin shaft portion having a structure in which the tube portion is insert-molded. It is preferable that the roller is a transport roller.
From the viewpoint of suppressing deformation of the tube portion, the Young's modulus of the resin constituting the tube portion at 25 ° C. is preferably 100 MPa or more.
Further, the fact that the resin portions constituting the shaft portion are in contact with both end surfaces of the tube portion means that the resin portion holds the tube portion due to the contraction of the shaft portion during the insert molding, and the tube portion is the shaft. This is preferable because it has the effect of suppressing idling with respect to the portion.
Further, from the viewpoint of expressing the effect of the present invention, it is preferable to satisfy the above formula (1).
The transport roller of the present invention can be suitably provided in an electrophotographic image forming apparatus.

Hereinafter, the present invention, its constituent elements, and modes and modes for carrying out the present invention will be described in detail. In the present application, "-" is used to mean that the numerical values described before and after the value are included as the lower limit value and the upper limit value.

<< Outline of manufacturing method of transport roller >>
The method for manufacturing a transport roller of the present invention is a method for manufacturing a transport roller having a resin shaft portion and a resin tube portion, wherein the tube portion is set in a mold and further melted for molding. It is characterized by having a step of filling the tube portion with a resin and molding the shaft portion.
In the present invention, a resin tube portion is set in a mold, and a molten molding resin is filled in the tube portion to form a resin shaft portion, whereby the shaft portion and the tube portion are formed. The molding method of integration is also referred to as "insert molding".

The resin shaft portion is used as a molding resin melted during insert molding, and it is preferable that the tube portion is held by the shrinkage force of the molding resin of the shaft portion during cooling. Therefore, the resin used for the shaft portion is preferably a heat-shrinkable resin.
The resin tube portion needs to be prepared in advance.
As a method of integrally molding such different members, a method of two-color molding of a tube portion and a shaft portion is known. Here, it refers to a technique of molding two types of resins different from two-color molding into one part.

However, in the above method, equipment for two-color molding is required, productivity is poor due to complicated mold mechanism for molding twice, and adhesion between the shaft portion and the tube portion is provided. Therefore, there are problems such as difficulty in mold processing and molding because the uneven shape is imparted.

According to the present invention, the resin tube portion can be used on the outer surface side, the shape change of the tube portion due to the influence of the contraction of the shaft portion during insert molding can be reduced, and the shape accuracy is low. It is possible to realize a high-performance transport roller, and since different materials can be used for the tube portion that is mainly in contact with the object to be transported and the shaft portion that supports rotation, it is possible to obtain a highly functional transport roller.

It is not necessary to make the tube part with the same mold, and the manufacturing method may be injection molding as well as cutting out of an extruded tube.
Known molding methods for obtaining a molded product of a tube portion include, for example, an injection molding method, an injection compression molding method, an extrusion molding method, a deformed extrusion method, a transfer molding method, a hollow molding method, a gas-assisted hollow molding method, and a blow. Molding method, extrusion blow molding, IMC (in-mold coating molding) molding method, rotary molding method, multi-layer molding method, two-color molding method, insert molding method, sandwich molding method, foam molding method, pressure molding method, etc. Can be mentioned.

Specifically, in the insert molding, the molten resin for molding is filled and transferred to both end surfaces of the resin tube portion and then cooled, so that the shrinkage force of the molding resin during cooling causes the shrinkage force of the molding resin. It is preferable to hold the tube portion and the molding resin portion.

With this method, it is possible to create a protrusion groove on the outer peripheral surface of the resin part even if the tube part is used.

<< Overview of transport rollers >>
The transport roller of the present invention is a transport roller that transports an object to be transported, and the transport roller has a resin tube portion and a resin shaft portion having a structure in which the tube portion is insert-molded. It is characterized by having.

The transport roller of the present invention can be applied to at least one of the above-mentioned transport roller (drive roller) or the resin roller (roller) driven by the drive roller, and is preferably applied to the resin roller.
Further, the “object to be transported” is one that is transported by the above-mentioned transport roller, and includes a so-called recording medium. As the recording medium, various media such as paper, resin plate, metal, cloth, and rubber can be used. Examples of the paper include plain paper, paperboard, coated paper, resin-coated paper, and synthetic paper.

FIG. 2 is an example of a cross-sectional view of the transport roller of the present invention. This is an example applied to a resin roller as a transport roller. The transport roller (resin roller) 11 of the present invention includes a resin tube portion 12 and a resin shaft portion 13 having a structure insert-molded into the resin tube portion 12. In this example, the resin portions 14 constituting the shaft portion 13 are in contact with both end faces of the resin tube portion 12, but the resin tube portion 12 extends to the surface end portion when the object to be transported mainly contacts. It may be. Since the resin portions 14 constituting the shaft portion 13 are in contact with both end faces of the resin tube portion 12, the resin portion 14 holds the tube portion 12 by shrinkage of the shaft portion during insert molding. It is a preferable embodiment.

By using such a transport roller 11, the resin tube portion can be used on the outer surface side, and the shape change of the tube portion due to the influence of the contraction of the shaft portion during insert molding can be reduced. Therefore, it is possible to realize a method for manufacturing a transport roller and a transport roller that are inexpensive and have high shape accuracy.
Further, as a preferred embodiment, by using different constituent materials for the tube portion that is mainly in contact with the object to be transported and the shaft portion that supports rotation, the transport roller 11 is made into a transport roller that is inexpensive and has excellent adhesion resistance to toner. be able to.

FIG. 3 is an example of an external perspective view of the transport roller 11 of the present invention. The transport roller 11 of the present invention preferably has a groove shape 15 on the outer peripheral surface of the resin portion 14. By having such a groove, it becomes easy to eject the object to be transported at the time of discharge, which is preferable in realizing stable transportation.

<< Materials used in manufacturing methods >>
[Tube]
The transport roller of the present invention includes a resin tube portion and a resin shaft portion having a structure insert-molded in the tube portion. Since the resin tube portion is in contact with the object to be transported, a resin having various functions different from that of the shaft portion can be used.
When functioning as a driven roller, it does not have to be an elastic body, and the Young's modulus of the resin constituting the tube portion at 25 ° C. is 100 MPa or more in order to suppress deterioration of the roundness of the tube portion due to molding shrinkage. That is preferable.

(Resin used for tube part)
The resin used for the tube portion is not particularly limited and can be selected according to the purpose.
Specifically, instead of POM, which has been used mainly from the viewpoint of slidability, the shaft part and the tube part are made independent, and the tube part is changed to a resin having higher antifouling property, which is a conventional problem. It is possible to reduce the adhesion of toner on the resin roller that has become.
Conventionally, a fluorine-based resin, which is expensive and takes time to process, has been used to prevent this, but it is preferable to use a water-repellent resin for the tube portion because the adhesion of toner can be reduced. .. The water repellency angle of the tube portion at 25 ° C. is preferably 90 ° or more.

The water repellency angle is measured by dropping minute water droplets on the surface of the tube portion with a microsyringe, shining light from one side and passing the objective lens provided on the other side to measure the contact angle of the water droplets with respect to the tube portion. It can be done by. Specifically, it can be obtained by measuring the contact angle using an image processing type contact angle meter (CA-X150 type manufactured by Kyowa Interface Science Co., Ltd.).

The tube portion preferably contains a polyolefin-based resin because it has a large water-repellent angle and an effect of preventing toner adhesion can be obtained. Examples of the polyolefin-based resin include polyethylene, polypropylene, ethylene-vinyl acetate copolymer, polypropylene-polystyrene copolymer, and polypropylene acrylic acid ester copolymer. Of these, it is preferable that the tube portion contains polypropylene.
The polyolefin-based resin may be used alone or in combination of two or more.

[Shaft]
The resin shaft portion used in the transport roller of the present invention has a structure in which a tube portion is insert-molded.

(Resin used for shaft)
In the case of the configuration shown in FIG. 2 having the resin portion 14, it is preferable that the tube portion is held by the resin portion 14 by the contraction force of the molding resin of the shaft portion when the insert molding is cooled. The resin used in is preferably a resin that shrinks after insert molding.

Examples of the heat-shrinkable resin include polyvinyl chloride resin, polyethylene resin, polypropylene resin, polyvinylidene chloride resin, polystyrene resin, polyester resin and the like.

Further, the shaft portion supports the transport roller, and wear resistance is required when transporting the object to be transported.
Table I shows the results of wear resistance tests of various resins. The test materials are polymethylmethacrylate (PMMA), polytetrafluoroethylene (PTFE), rubber-modified polystyrene (HIPS), perfluoroalkoxy alkanesyl (PFA), polypropylene (PP), and polyphenylene sulfide (PPS) shown in Table I. , Polyetheretherketone (PEEK), nylon (PA66), ultrahigh molecular weight polyethylene (PE) and polyacetal (POM). From Table I, a material having good wear resistance, which is preferable as the resin used for the shaft portion, can be selected.

From Table I, the members of the shaft according to the present invention include polyacetal (POM), ultrahigh molecular weight polyethylene (PE), nylon (PA66), and polyphenylene sulfide (PPS), which have better wear resistance than polypropylene (PP). , Or polyetheretherketone (PEEK) is preferably used. Among them, it is preferable that the member of the shaft portion contains polyacetal (POM) from the viewpoint of wear resistance and cost.

(Abrasion resistance test)
The above wear resistance test was performed as follows.
4A and 4B are schematic views illustrating an outline of the wear resistance test.
As shown in FIG. 4A, a steel wire spring 202 is brought into point contact with various cylindrical resin materials 201, and the resin material is rotated while applying a pressure (about 140 MPa) equivalent to that of a resin roller at the time of paper ejection. After the test for a certain period of time, the wear depth of the resin (see FIG. 4B) is measured and converted into a wear volume.

It is also preferable that the shaft portion contains a resin strengthening agent in order to improve the strength. For example, a fibrous filler such as polybenzazole fiber, carbon fiber, aramid fiber, metal fiber, glass fiber, ceramic fiber or polyparaphenylene terephthalamide fiber can be mixed in the thermoplastic resin forming the shaft portion. preferable. Above all, the fibrous filler is more preferably at least one of carbon fibers and glass fibers.

Specific examples of the fibrous filler include carbon fiber milled fiber (manufactured by Mitsubishi Chemical Co., Ltd.), glass fiber T-289DE (manufactured by JEOL Ltd.), milled fiber (manufactured by Asahi Glass Fiber Co., Ltd.), and the like. Can be done.

Further, the tube portion and the shaft portion may contain various polymers and additives other than the resin as long as the object of the present invention is not impaired. Specific examples of additives include antioxidants, heat-resistant stabilizers, weather-resistant stabilizers, light-resistant stabilizers, UV absorbers, antistatic agents, anti-aging agents, fatty acid metal salts, softeners, dispersants, nucleating agents, and lubricants. , Flame retardants, pigments, dyes, organic fillers.

[Adhesion between shaft and tube]
FIG. 5 is a diagram for explaining the adhesion between the shaft portion and the tube portion.
In the transport roller (resin roller) 11 of the present invention having the shaft portion 13 and the tube portion 12, the resin portions 14 constituting the shaft portion are in contact with both end surfaces of the tube portion 12, and the resin portion 14 is the insert. It is preferable that the tube portion is held by the contraction of the shaft portion during molding.
The white arrow in the figure indicates the direction in which the shaft contracts. That is, it is preferable to arrange the resin portions constituting the shaft portion on both end surfaces of the tube portion and hold the tube portion by the contraction force thereof.
The adhesion force N [N: Newton] between the tube portion and the shaft portion can be expressed by the following formula (A).

Equation (A)
N = μεAE
In the formula (A), μ represents the coefficient of friction between the resin constituting the tube portion and the shaft portion. ε represents the strain [dimensionless] of the tube portion due to molding. A [mm ² ] represents the cross-sectional area where both end faces of the tube portion are in contact with the shaft portion. E [MPa] represents Young's modulus of the tube portion.

6A and 6B are schematic views illustrating a method for measuring the adhesion force. The adhesion force N can be measured as follows. A tape (7413D manufactured by polyimide tape 3M) 21 is wound around the tube portion 12 of the resin roller and pulled in the direction of the white arrow, and the magnitude of the force when the belt 22 attached to the shaft portion 13 starts to slide is measured. As a measuring device, a tensile tester (autograph manufactured by Shimadzu Corporation) can be used for measurement.

FIG. 7 is an example of a diagram showing the relationship between the theoretical adhesion force N and the actually measured adhesion force N. Specifically, the resin rollers having the configuration shown in FIG. 2 which were insert-molded under the molding conditions shown in Example 2 described later with each combination of the material of the tube portion and the shaft portion were evaluated, and the vertical axis is the actual measurement. The value and the horizontal axis show the theoretical value obtained by the formula (A). The tube portion used was injection molded. A tube portion having a length of 12.6 mm was used.
In the figure, for example, the abbreviation of "PFA 9 × 10" indicates that PFA (perfluoroalkoxy fluororesin) having an inner diameter of 9 mm and an outer diameter of 10 mm was used as the tube portion.
The following resin materials were used as the shaft portion and the tube portion.

Shaft POM: Polyacetal (Iupital F20-03 (manufactured by Mitsubishi Engineering Plastics Co., Ltd.))
POM Inorganic: Inorganic-filled polyacetal (Iupital TC3015 (manufactured by Mitsubishi Engineering Plastics Co., Ltd.))
HDPE: High-density polyethylene (HIZEX 2200J (manufactured by Prime Polymer Co., Ltd.))
Tube part PTFE: Polytetrafluoroethylene (manufactured by Hagitech Co., Ltd .: 8 × 10, model number 244-1031-75: 9 × 10, model number 244-1031-64)
PFA: Perfluoroalkoxy alkane resin (manufactured by Hagitech Co., Ltd .: 9 × 10: model number 02-032-11-02)
Ultra High Molecular Weight PE: Polyethylene Resin (Saxin New Light, manufactured by Saxin Industry Co., Ltd.)
The physical property values of the materials used are as follows. The coefficient of linear expansion described in the description of the formula (2) is also described.

In calculating the theoretical adhesion force from the formula (A), the Young's modulus used a general physical property value. The cross-sectional area A was calculated from the outer diameter and wall thickness of the tube of the tube portion. ε was calculated by (tube length change) / (tube length) by measuring the axial length of the tube before and after molding. For the coefficient of friction, prepare flat plates made of the same material as the tube and molding resin, stack the flat plates on top of each other, place a weight on them, tilt the entire plate, and set the angle θ at which the flat plates slide out under the condition that the tilt angle is less than 3 ° / sec. Read and set the tangent tan θ of θ as the coefficient of static friction μ.

From FIG. 7, it can be seen that the theoretical adhesion force N shows a good correlation with the measured value. In order to increase the adhesion, a combination of a tube having a larger coefficient of friction and a molding resin is preferable. The larger the cross-sectional area of the tube, the greater the adhesion. In this way, the adhesion can be adjusted by appropriately selecting a material or the like.
The required adhesion varies depending on the intended use, but if it is about 2N or more, the adhesion is good.

[Roundness of tube part]
During insert molding, if the shrinkage of the shaft portion indicated by the white arrow in FIG. 8 is large, the adhesion force N between the tube portion 12 and the shaft portion 13 increases, but if the shrinkage amount is too large, the center of the tube portion 12 swells. The tube part may be deformed. In order to reduce the strain ε of the tube portion during such molding, it is preferable to satisfy the following general formula (1).

Equation (1)
ε = P / AE <0.17
(In the formula (1), ε represents the strain [dimensionless] of the tube portion due to molding. P represents the molding shrinkage force represented by the following formula (2). A is on both end faces of the tube portion. Represents the area of the portion in contact with the resin portion. E represents the Young ratio of the resin constituting the tube portion at 25 ° C.)

Equation (2)
P = Young's modulus of the resin constituting the shaft at 25 ° C. × Cross-sectional area of the resin constituting the shaft × (Shaft molding shrinkage-Tube shrinkage)
AE represents the axial rigidity of the tube.
The cross-sectional area [mm ² ] of the resin constituting the shaft portion is specifically the cross-sectional area of the portion surrounded by the inner diameter of the tube portion 12 shown in FIG. 5 described above.
The shrinkage of the shaft is calculated from the mold size and the size of the molded product.
The coefficient of contraction of the tube portion is calculated by multiplying the linear expansion coefficient of the tube portion (25 ° C.) by the difference between the mold temperature and the room temperature during the resin cooling step. Specifically, it can be calculated from the following formula.
Tube part shrinkage rate = tube part linear expansion rate (25 ° C) x (mold temperature-room temperature (25 ° C))

ε can be a measure of roundness. In the present invention, the "roundness" refers to the magnitude of deviation from a geometrically correct circle, that is, the deviation of each diameter of a circle having a constant cross section. It is preferable that the value of roundness is small because the deviation from the geometrically correct circle is small.
In the present invention, the roundness is measured by measuring the diameters in three directions between the outer surfaces of the tube portions forming 45 ° with each other with a commercially available roundness measuring device as shown in FIG. 9B, and measuring the diameters in the three directions. , The value of the difference between the maximum value and the minimum value was defined as the roundness. As shown in FIG. 9A, the measurement positions 15 are three points at the end and the center of the tube portion 12, and the average value of the three points can be calculated as the roundness.

According to the present invention, it is possible to provide a method for manufacturing a transport roller having a low roundness value and high shape accuracy and a transport roller. It is preferable that ε represented by the formula (1) is smaller than 0.17.

<< Details of manufacturing method of transport roller >>
The details of the manufacturing method of the transport roller will be further described below.
FIG. 10 is a cross-sectional view of an example of the insert-molded transport roller 11 (resin roller).

11A to 13F are views for explaining insert molding used in the present invention.
As shown in FIG. 11A, using a known insert jig (not shown), a separately molded tube portion 12 is set, and the opening / closing dies 31 and 32 and the mounting jig (not shown) are set. Position with and set in place.

Next, as shown in FIG. 11B, the tube portion 12 was inserted into the mold 31 during mold opening, and as shown in FIG. 12C, after the mold was clamped, the resin melted in the mold to which the tube portion 12 was mounted. Is injected from the runner 33 into the space forming the shaft portion (FIGS. 12C and 12D) to form the shaft portion (FIG. 13E).

Then, after sufficiently cooling, the

molds

31 and 32 are opened in FIG. 13F to obtain a resin roller 11 in which the tube portion and the shaft portion are integrated. At this time, it is preferable to project and take out by an ejector pin or the like as in normal injection molding. After taking it out, the gate is cut to separate the molded part from the runner or the like.

[Use]
The transport roller of the present invention is a transport roller that transports an object to be transported, and the object to be transported includes a so-called recording medium, and the recording medium includes various types such as paper, resin plate, metal, cloth, and rubber. Medium can be used. Examples of the paper include plain paper, paperboard, coated paper, resin-coated paper, and synthetic paper.

Examples of the device provided with the transport roller for transporting such a recording medium include an inkjet printer, a laser beam printer, an electrophotographic image forming device, a fax device, and a scanner. Among these, it is preferable to apply it to an electrophotographic image forming apparatus.

Specifically, for example, an electrostatic latent image is formed on the photoconductor by a charging / exposing means, and the electrostatic latent image is developed by a developing agent containing a toner to form a toner image. , The toner image is transferred onto a recording medium such as paper or a sheet by a transfer means, and the toner image is fixed on a recording medium by using heat, solvent, pressure or the like by a fixing means to obtain a permanent image. It is preferable to provide it in an electrophotographic image forming apparatus capable of forming the same.
It is preferable to use these devices as rollers for conveying the recording medium. Specifically, it can be used as at least a part of the transport unit as shown in FIG. The transport roller of the present invention is preferably applied to a resin roller (roller).

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, the indication of "parts" or "%" is used, but unless otherwise specified, it indicates "parts by mass" or "% by mass".

[Example 1]
(Toner adhesion test)
Process blue (made of cyan and magenta) solid-printed paper was set on various resin sheets, the temperature was changed as shown in Table III, and pressure (0.5 MPa) was applied to perform an adhesion test. .. It was evaluated whether the toner component of the printing paper was transferred to the resin sheet, visually observed, and ranked as follows. The results are shown in Table III. "Deformation" in the table indicates that the resin sheet was deformed by the temperature.

The following materials were used for the resin sheet. The ultra-high molecular weight PE sheet was prepared by the manufacturer, and the other sheets were prepared by injection molding by purchasing resin pellets.
PE: Polyethylene resin (HJ580N, manufactured by Japan Polyethylene Corporation)
Ultra high molecular weight PE: Polyethylene resin (New Light Sheet NL-W, manufactured by Saxin Industry Co., Ltd.)
PP: Polypropylene resin (BC3AD, manufactured by Nippon Polypropylene)
PC: Polycarbonate resin (H3000R, manufactured by Mitsubishi Engineering Plastics)
POM: Polyacetal (F20-03, manufactured by Mitsubishi Engineering Plastics)

〇: No adhesion is observed △: Slight adhesion is observed ×: High adhesion

(Measurement of water repellency angle)
Each resin sheet was measured in an environment of 25 ° C. by the method described above.

From Table III, if the water repellency angle is 90 ° or more, no toner adhesion is observed. When POM was used, the amount of toner adhered was larger than that of PC.

[Example 2]
A resin roller was manufactured by the manufacturing method using the mold described above.
[Manufacturing of resin roller 1]
(Making the tube part)
A tube portion made of PE having a diameter of 10.0 mm, a length of 12.6 mm, and a tube thickness of 1.0 mm was prepared in advance by injection molding.

(Making the shaft)
The resin roller 1 of the present invention was produced by insert molding by the method described above under the following conditions.

(Molding condition)
Shaft resin: POM
Resin temperature: 210 ° C
Mold temperature: 70 ° C
Holding pressure condition: 80MPa-3s

[Manufacturing of resin roller 2]
In the production of the resin roller 1, a tube having a diameter of 10 mm and an inner diameter of 8 mm is cut out to a length of 12.6 mm with a tube cutter, and a tube portion having the same shape is produced using the material ultra-high molecular weight PE shown in Table III, and then the resin roller is produced. The resin roller 2 of the present invention was produced by insert molding a POM on the shaft portion in the same manner as in the production of 1.

[Manufacturing of resin rollers 3 to 4]
In the production of the resin rollers 3 to 4, the resin of the tube portion is produced by using the materials PP and PC shown in Table III, respectively, and then the tube portion having the same shape as the resin roller is produced, and then in the same manner as in the production of the resin roller 1. The

resin rollers

3 and 4 of the present invention were produced by insert molding POM on the shaft portion.

[Preparation of resin roller 5]
A resin roller 5 made of POM having the same shape as the resin roller 1 was manufactured by injection molding without separating the tube portion and the shaft portion. Specifically, the molten POM used for the shaft portion was inserted into the mold without loading the tube portion into the mold to produce a comparative resin roller 5.
The following materials were used for the tube part and the shaft part. The ultra-high molecular weight PE tube was prepared by the manufacturer, and the others were formed by injection molding by purchasing resin pellets.
PE: Polyethylene resin (HJ580N, manufactured by Japan Polyethylene Corporation)
Ultra high molecular weight PE: Polyethylene resin (New Light Tube, manufactured by Saxin Industry Co., Ltd.)
PP: Polypropylene resin (BC3AD, manufactured by Nippon Polypropylene)
PC: Polycarbonate resin (H3000R, manufactured by Mitsubishi Engineering Plastics)
POM: Polyacetal (F20-03, manufactured by Mitsubishi Engineering Plastics)

[Toner adhesion test]
Using bizhub C4050i as an electrophotographic image forming apparatus, a resin roller (roller) of a paper ejection roller of a paper ejection unit is attached, and a resin roller after printing 200 solid images using plain paper in an environment of a temperature of 20 ° C. The amount of toner adhering to the paper was observed.
Similar to Example 1, toner adhered to the resin roller 5 having POM in the tube portion was observed, and toner adhered slightly to the resin roller 5 having POM in the tube portion. However, the results obtained that no toner adhered to the resin rollers 1 to 3 having PE, ultra-high molecular weight PE or PP of the present invention.

[Example 3]
(Making resin rollers)
Using the molding conditions of Example 2, a resin roller that was insert-molded with each combination of the above-mentioned materials of the shaft portion and the tube portion used in the measurement of the adhesion force was produced.
That is, the resin roller shown in FIG. 14 was produced by the following combination of the shaft portion and the tube portion.

Shaft POM: Polyacetal (Iupital F20-03 (manufactured by Mitsubishi Engineering Plastics Co., Ltd.))
POM Inorganic: Inorganic-filled polyacetal (Iupital TC3015 (manufactured by Mitsubishi Engineering Plastics Co., Ltd.))
HDPE: High-density polyethylene (HIZEX 2200J (manufactured by Prime Polymer Co., Ltd.))

Tube part PTFE: Polytetrafluoroethylene (manufactured by Hagitec Co., Ltd .: 8 × 10, model number 244-1031-75: 9 × 10, model number 244-1031-64)
PFA: Perfluoroalkoxy alkane resin (manufactured by Hagitech Co., Ltd .: 9 × 10: model number 02-032-11-02)
Ultra High Molecular Weight PE: Polyethylene Resin (Saxin New Light, manufactured by Saxin Industry Co., Ltd.)

(Evaluation of resin roller accuracy)
The shape accuracy of each of the produced resin rollers was evaluated by the roundness and the strain ε of the tube portion formed by molding represented by the formula (1). The roundness was measured by the method described above.
The results are shown in FIG. FIG. 14 shows the relationship between ε and roundness. The vertical axis is the actually measured roundness [mm], and the horizontal axis is the value of ε calculated from the equation (1). In the figure, for example, the abbreviation of "PFA 9 × 10" indicates that PFA (perfluoroalkoxy fluororesin) having an inner diameter of 9 mm and an outer diameter of 10 mm was used as the tube portion as in FIG. 7.
From FIG. 14, it can be seen that the strain ε of the tube portion due to molding correlates well with the actual roundness. That is, it is possible to clarify the material physical characteristics and the range thereof necessary for suppressing the deformation due to molding.

Separately, the roundness of the comparative resin roller 5 integrally molded using POM produced in Example 2 was measured and found to be 0.23 mm, as compared with the resin roller having the insert-molded structure of the present invention. , The value of roundness was large and the shape accuracy was inferior.

From the above results, it was found that a transport roller that is inexpensive and has high shape accuracy can be realized. Further, it was found that by using different materials for the material constituting the shaft portion and the material constituting the surface of the transport roller, a highly functional transport roller having excellent adhesion resistance can be obtained.

The transport roller of the present invention is a transport roller that transports an object to be transported, and has features of low cost and high shape accuracy. As the recording medium, various media such as paper, resin plate, metal, cloth, and rubber can be used. Examples of the paper include plain paper, paperboard, coated paper, resin-coated paper, and synthetic paper.

1 Roller used for the transport unit 2 Transport roller 3 Shaft 4 Elastic body part 5 Gear part 6 Resin roller 7 Groove shape 11 Transport roller (resin roller)
12 Tube part 13 Shaft part 14 Resin part 15

Groove shape

31, 32 Mold 33 Runner 201 Resin material 202 Wire spring

Claims

A method for manufacturing a transport roller having a resin shaft portion and a resin tube portion.
A method for manufacturing a transport roller, which comprises a step of setting the tube portion in a mold, further filling the tube portion with a molten molding resin, and molding the shaft portion.
The tube portion and the shaft portion are held by the shrinkage force of the molding resin at the time of cooling by filling both end surfaces of the tube portion with the molten molding resin and then cooling the tube portion. The method for manufacturing a transport roller according to claim 1.
The method for manufacturing a transport roller according to claim 1 or 2, wherein the Young's modulus of the resin constituting the tube portion at 25 ° C. is 100 MPa or more.
The method for manufacturing a transport roller according to any one of claims 1 to 3, wherein both end faces of the tube portion are in contact with the resin portion constituting the shaft portion.
The method for manufacturing a transport roller according to claim 4, wherein the outer peripheral surface of the resin portion has a groove shape.
The following formula (1) is satisfied by controlling the molding shrinkage force P, the area A of the portion where the resin portion contacts both end surfaces of the tube portion in the previous period, and the Young's modulus E of the resin constituting the tube portion. The method for manufacturing a transport roller according to claim 4 or 5.
Equation (1)
ε = P / AE <0.17
(In the formula (1), ε represents the strain of the tube portion due to molding. P represents the molding shrinkage force represented by the following formula (2). A represents the resin portion in contact with both end surfaces of the tube portion. Represents the area of the portion. E represents the Young's modulus of the resin constituting the tube portion at 25 ° C.)
Equation (2)
P = Young's modulus of the resin constituting the shaft at 25 ° C. × Cross-sectional area of the resin constituting the shaft × (Shaft molding shrinkage-Tube shrinkage)
The method for manufacturing a transport roller according to any one of claims 1 to 6, wherein the water repellency angle of the tube portion at 25 ° C. is 90 ° or more.
The method for manufacturing a transport roller according to any one of claims 1 to 7, wherein a polyolefin-based resin is used as a constituent material for the tube portion.
The method for manufacturing a transport roller according to any one of claims 1 to 8, wherein polypropylene is used as a constituent material for the tube portion and polyacetal is used for the shaft portion.
A transport roller that transports the object to be transported.
A transport roller, characterized in that the transport roller includes a resin tube portion and a resin shaft portion having a structure in which the tube portion is insert-molded.
The transport roller according to claim 10, wherein the Young's modulus of the resin constituting the tube portion at 25 ° C. is 100 MPa or more.
The transport roller according to claim 10 or 11, wherein the resin portions constituting the shaft portion are in contact with both end surfaces of the tube portion.
The transport roller according to claim 12, wherein the following formula (1) is satisfied.
Equation (1)
ε = P / AE <0.17
(In the formula (1), ε represents the strain of the tube portion due to molding. P represents the molding shrinkage force represented by the following formula (2). A represents the resin portion in contact with both end surfaces of the tube portion. Represents the area of the portion. E represents the Young's modulus of the resin constituting the tube portion at 25 ° C.)
Equation (2)
P = Young's modulus of the resin constituting the shaft at 25 ° C. × Cross-sectional area of the resin constituting the shaft × (Shaft molding shrinkage-Tube shrinkage)
An electrophotographic image forming apparatus comprising the transport roller according to any one of claims 10 to 13.