JP2001347557A - Rubber roller manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a rubber roller which can be molded by an extrusion molding process and is free from surface roughening with a high coefficient of friction, as a rubber roller composed mainly of a high viscosity thermoplastic elastomer. SOLUTION: This rubber roller is manufactured by extrusion-molding a rubber material composed mainly of a thermoplastic elastomer in the form of a tube using an extrusion molding machine and cutting the tube. In this case, the extrusion molding machine to be used has a diehead machined so that the value of the ratio L/D, that is, the ratio of the length L in the longer direction of a cylindrical space 20 formed by a mandrel 12 and a die 13, to the inside diameter D of an extrusion orifice of the die 13, is 2 or more and the value of the surface roughness Ra of the surface of the mandrel 12 and the inner face of the die 13 is 6 μm or less in the diehead part of the machine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for manufacturing a rubber roller used as a paper feed roller of OA equipment.
In particular, the present invention is suitable for manufacturing a separation rubber roller for picking up a conveyed object such as paper requiring abrasion resistance.

[0002]

2. Description of the Related Art A paper feed rubber roller is used in a paper feed mechanism of various OA devices such as a laser printer, an electrostatic copying machine, a plain paper facsimile machine, and an ATM. Since the rubber roller for feeding paper feeds a sheet such as paper or film, a high coefficient of friction with the sheet is required. Usually, the paper feed roller is made of a rubber material such as EPDM, natural rubber, urethane rubber, and chloroprene rubber.

When extruding a rubber roller of this type, a rubber material is extruded into a tube-like space into a cylindrical space formed by an inner mandrel and an outer die at a die portion of the extruder, and then extruded. After being cured by sulfuration, it is cooled and polished, then cut into a predetermined length, and a shaft roller is inserted into a hollow portion to produce a rubber roller.

[0004] Specifically, in the first step, a vulcanizing agent, a filler, various additives, a vulcanization aid, and the like are added to the unvulcanized rubber material, and the mixture is kneaded with a kneader such as a kneader, a Banbury, or a roll. In the second step, the rubber raw material is charged into a rubber extruder and extruded into a tube. In the third step, the core rod is inserted into a tube-shaped tubular body, and is heated and vulcanized in a vulcanizing can or the like. In the fourth step, cooling is performed, and after cooling, the surface is polished to adjust the outer diameter. In the fifth step, the product is cut to a predetermined length to obtain a product.

[0005] However, since the above-mentioned manufacturing process has many steps and many manual operations, it is not easy to achieve full automation. Further, since a rubber material is used as a raw material and vulcanization is performed after extrusion, it is difficult to obtain dimensional accuracy of the roller. In addition, since it is made of a rubber raw material, the surface becomes rough at the time of extrusion, so that a surface polishing step is always required, which causes problems such as an increase in cost.

Therefore, Japanese Patent Application Laid-Open No. Hei 9-156784 proposes a method of manufacturing a rubber roller by extrusion molding using a resin material containing a thermoplastic elastomer as a main component, which has high dimensional accuracy and is easily automated.

[0007]

However, many thermoplastic elastomer materials exhibiting good performance as a rubber roller have a high viscosity. If these high-viscosity raw materials are used, extrusion molding becomes extremely difficult, and molding is difficult. There is a problem that the surface of the rubber roller becomes rough. In particular, in the case of a rubber roller for paper feeding requiring a high coefficient of friction, it is necessary to use a material having a high viscosity. When extruding a high-viscosity material of this kind, for example, an olefin-based thermoplastic elastomer having an apparent melt viscosity of 744 Pa * sec (shear rate 100 / sec), when extruding the raw material, a mandrel and a mandrel are formed in a die portion of an extruder. Since the frictional resistance with respect to the die is increased, the surface of the formed rubber roller is apt to have a crumpled shape. Therefore, it is very difficult for a general tube extruder to produce a rubber roller having a smooth surface using the high-viscosity thermoplastic elastomer.

The present invention has been made in view of the above problems, and has as its object to form a rubber roller having a smooth surface by extrusion using a high-viscosity thermoplastic elastomer.

[0009]

In order to solve the above-mentioned problems, the present invention provides a method in which a thermoplastic elastomer is filled in a cylindrical space formed by an inner mandrel and an outer die in a die portion of an extruder. A rubber roller manufacturing device manufactured by extruding a raw material as a main component into a tube shape, cutting the extruded material into a predetermined length, and inserting a shaft core into a hollow portion, the cylindrical shape being formed by the mandrel and a die. Length L of the straight part in the longitudinal direction of the space
A ratio of L / D to the inner diameter D of the die is 2 or more, and the surface roughness Ra of the outer surface of the mandrel and the inner surface of the die is 6 μm or less. Is provided.

The reason that the value of the ratio L / D is 2 or more is that when the value of L / D is smaller than 2, the raw material is extruded before the internal pressure of the extruded raw material becomes sufficiently uniform. This causes cracks and deformation inside the rubber roller.

The reason for setting the surface roughness Ra of the outer surface of the mandrel and the inner surface of the die to 6 μm or less is that when the value of Ra is 6 μm or less, the surface has almost no irregularities.
The surface becomes smooth. Therefore, the resistance at the time of extruding the raw material is reduced, the raw material is easily extruded, and the extrusion molding can be performed even with a raw material having a high viscosity such as a thermoplastic elastomer. For the above-mentioned reason, if the value of the surface roughness Ra is 6 μm or less, a value as small as possible is preferable. If the value of the surface roughness Ra exceeds 6 μm, the extrusion resistance increases, and the rubber roller surface becomes rough.

The length L of the straight portion of the cylindrical space is preferably 60 mm or more. This is because if the value of L is smaller than 60 mm, the raw material is extruded before the internal pressure of the extruded raw material becomes sufficiently uniform, and cracks and deformation inside the rubber roller occur.

According to the manufacturing apparatus of the present invention described above, a rubber roller having a smooth surface and a high friction coefficient can be obtained from a raw material made of a high-viscosity thermoplastic elastomer by an extrusion manufacturing method. In addition, since molding is performed using a raw material containing a thermoplastic elastomer as a main component, a vulcanizing step by heating in a vulcanizing can, which was necessary when a conventional rubber material is used, is unnecessary, and Also, the cooling step is unnecessary. Further, since the surface of the rubber roller to be molded is smooth, a polishing step is not required, and the number of steps can be reduced.
In addition, since the shape is defined in the extrusion step as compared with the case where the composition is hardened by vulcanization after the extrusion step as in the related art, a dimensional accuracy can be easily obtained, and a highly accurate rubber roller can be manufactured.

[0014] Further, a knurl groove forming portion provided with a plurality of minute grooves in the axial direction may be provided at least at the transfer end portion on the inner peripheral surface of the die. By providing the knurled groove forming portion, a knurled pattern composed of grooves in the axial direction can be formed on the surface of the extruded tube. When a knurl groove is provided at a required portion of the rubber roller by the knurl groove shaping portion, paper dust or the like adhering to the roller surface enters the groove, and a reduction in frictional engagement of the roller surface due to the paper dust can be suppressed.

The cylindrical space formed by the mandrel and the die is cylindrical, and the tube extruded by the extruder has a cylindrical shape. The shaft inserted into the hollow portion has a D-shaped cross section. A D-shaped deformed rubber roller can also be used.

The raw material thermoplastic elastomer to be extruded has a melt viscosity η of 2 at a shear rate of 100 / sec.
It is preferably 00 Pa * sec or more and Shore A hardness is 50 or less and 10 or more.

The above-mentioned shear rate is a shear rate applied during extrusion molding, and the melt viscosity is measured based on this shear rate. Melt viscosity of thermoplastic elastomer is 200Pa
If it is less than * sec, the viscosity is low, so the extrusion tube is crushed and the rubber roller is deformed. Also,
If the hardness of the thermoplastic elastomer is greater than 50 in Shore A, the coefficient of friction of the rubber roller surface is low, and the performance as a rubber roller for paper feeding cannot be sufficiently obtained. If the hardness is less than 10, the friction resistance between the mandrel and the die of the extruder becomes large during extrusion.
Rolls are formed on the surface of the formed roller, and furthermore, the roller is easily worn and has a problem in abrasion resistance.

The following thermoplastic elastomers are preferably used as raw materials.・ Styrene-based thermoplastic elastomers such as SBS, SIS, SEBS, SEPS, etc. ・ Chlorinated polyethylene, PVC-based thermoplastic elastomer ・ Olefin-based thermoplastic elastomer, urethane-based thermoplastic elastomer, ester-based thermoplastic elastomer, amide-based thermoplastic elastomer, Ionomer, E
EA, EVA and mixtures thereof.-In addition, particles of crosslinked rubber and vulcanized rubber are dispersed in the thermoplastic elastomer and thermoplastic resin other than the thermoplastic elastomer by a technique such as dynamic crosslinking and a kneading technique. Resin raw material mainly composed of thermoplastic elastomer.

In order to reduce the hardness of the rubber roller, oil is blended in the rubber. As the oil, a mineral oil such as a paraffinic, naphthenic or aromatic oil, a synthetic oil known per se comprising a hydrocarbon oligomer, or a process oil can be used. As a synthetic oil,
For example, an oligomer of α-olefin, an oligomer of butene, an oligomer of ethylene and α-olefin, and the like can be given, and an amorphous oligomer of ethylene and α-olefin is particularly preferable. As the plasticizer, for example, dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl sepate (DOS), dioctyl adipate (DOA) and the like can be used.

[0020] In order to improve the mechanical strength of the rubber roller, a filler can be blended if necessary. Examples of the filler include powders such as silica, carbon black, clay, and talc. When a filler is compounded, it is preferable that the filler be 10% by weight or less based on the whole rubber roller. This is because, although the compounding of the filler is effective for improving the tensile strength and the tearing strength of the rubber, if the compounding is too large, the flexibility of the rubber is greatly reduced.

Further, in addition to the above-mentioned compounding agents, an antioxidant, a wax and the like can be added to the rubber roller, if necessary. Examples of the antioxidant include imidazoles such as 2-mercaptobenzimidazole, phenyl-α-naphthylamine, N, N-di-β-naphthyl-p-phenylenediamine, N-phenyl-N′-isopropyl-p-. Examples thereof include amines such as phenylenediamine.

The hardness of the manufactured rubber roller is JIS 63
The hardness as measured with an A-type hardness tester No. 01 is in the range of 15 to 45, preferably 20 to 40. Within this range, even if the rubber roller is pressed against the paper with a relatively small contact pressure, the rubber roller is sufficiently deformed and a large contact area with the paper can be obtained.

The rubber roller is formed in a cylindrical shape and has a thickness of 1 mm to 8 mm, preferably 1.5 mm.
５5 mm. This depends on the hardness of the rubber roller, but if the thickness is too small, a large contact area is hardly formed with paper even if the rubber roller is deformed. On the other hand, if the thickness is too large, the contact pressure on the rubber roller must be increased in order to deform the roller, and the mechanism for pressing the rubber roller in the following manner becomes large.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a D-shaped deformed rubber roller 1 for paper feeding manufactured by a manufacturing apparatus according to the present invention. The rubber roller 1 is made of a resin raw material containing a thermoplastic elastomer as a main component, and is extruded in a round shape. The rubber roller 1 is press-fitted into a D-shaped shaft core 2 in a hollow portion thereof or is fixed by bonding both with an adhesive. I have.

FIG. 2 is a schematic diagram in which the paper feed rubber roller 1 is applied to a paper feed roller of an ink jet printer, and a separation pad 3 is provided so as to face the rubber roller 1. When the shaft core 2 is rotated in the direction of the arrow, the rubber roller 1 is also rotated, and the paper 4 on the uppermost surface is rolled up, passed through the gap between the rubber roller 1 and the pad 3, and supplied to the inside of the printer. When the paper 4 breaks, the rubber roller 1 rubs against the pad 3. Therefore, the rubber roller 1
Is required to have abrasion resistance and a high coefficient of friction.

FIG. 3 shows a first embodiment of an apparatus for manufacturing the rubber roller 1. As shown in FIG. The extruder 10 includes a base 14 at the tip of a screw-type single-screw or twin-screw extruder 11. The raw material is charged from a hopper 18, and the raw material is kneaded while being heated by a heater 15 arranged on the outer peripheral surface of the outer cylinder of the screw-type extruder 11, and the kneaded raw material is supplied to a die unit 14. 19 is pushed out.

As shown in FIG. 4, the base 14 has a structure in which the die 13 is fitted to the mandrel 12 with a required space. As shown in FIG. 4 (A), the mandrel 12 constituting the base 14 has a conical shape on the side (X) continuous with the extruder, and has a straight portion 12b continuous with the enlarged portion 12a. ing. A die 13 which fits outside the mandrel 12 with a required space is a cylindrical shape having the appearance shown in FIG. 4 (B), and the side (X) continuous with the extruder is stepped like the mandrel 12. And a straight portion 13b is provided continuously to the enlarged portion 13a.

The straight portion 12b of the mandrel 12
FIG. 4 which is formed of the straight portion 13b of the die 13
The length L of the cylindrical space 20 shown in FIG.
m and the inner diameter D of the die 13 are set in a relationship of L / D ≧ 2. In this embodiment, L is 120 mm, D is
Is 30 mm, and L / D = 4.

The inner peripheral surface 13c of the die 13 surrounding the cylindrical space 20 and the outer peripheral surface 12c of the mandrel 12 are polished to have a surface roughness Ra of 0.5 μm or less, which is 0.6 μm or less. . In this embodiment, the mandrel 12 and the die 13 are formed of SUS304.

The molding of the rubber roller by the extruder 10 having the base 14 composed of the mandrel 12 and the die 13 first includes a thermoplastic elastomer as a main component.
In addition, all the raw materials including various additives such as a colored master batch are put into a hopper 18, kneaded while being heated by an extruder 11, and extruded into a die 14. In the base part 14, the dimensions are defined by extruding the inside of the cylindrical space 20 between the mandrel 12 and the die 13;
And the surface is smoothed. The cylindrical molded product extruded from the base 14 is cut into a required length, and fitted into a D-shaped shaft core to produce a D-shaped rubber roller.

FIGS. 5A and 5B show a second embodiment.
A die 13 ′ constituting the base 14 is provided with a minute groove 13 d ′ in the axial direction on the inner peripheral surface of the straight portion 13 b ′.
And a knurled groove forming portion 13e 'is provided. The groove 13d 'is provided on the inner peripheral surface of the die 13', and the inner peripheral surface of the die 13 'surrounding the cylindrical space 20 including the inner peripheral surface of the groove is the first peripheral surface. Like the embodiment, the surface roughness Ra is set to 0.6 μm or less.

When the knurl groove forming portion 13e 'is provided on the inner peripheral surface of the die 13', a knurl groove formed of minute grooves in the axial direction can be formed on the outer peripheral surface of the roller to be extruded. .

Hereinafter, Examples 1 to 6 and Comparative Examples 1 to 3 in which rubber rollers were manufactured using the apparatus of the above embodiment will be described. In Examples 1 to 6 and Comparative Examples 1 to 3, as shown in Table 1 below, the types and amounts of the raw materials to be molded and the dimensional conditions of the die and the mandrel of the die of the extruder were changed. The dies of the example and the comparative example had the shape of the first embodiment, and had no knurled grooves on the inner peripheral surface.

[0034]

[Table 1]

Example 1 As a rubber raw material, a thermoplastic elastomer obtained by dispersing EPDM rubber in a mixture of PP (polypropylene) and a styrene-based thermoplastic elastomer was used as a raw material, and the following compounding ratio was used. PP / styrene-based thermoplastic elastomer / EPDM = ratio 20/70/100 PP (Novatec PP BC6 manufactured by Nippon Polychem Co., Ltd.) Styrene-based thermoplastic elastomer (Septon 4055 manufactured by Kuraray Co., Ltd.) EPDM (Supremo Chemical Industries, Ltd. Esplen) 670
F) Shore hardness Hs = 35 Apparent melt viscosity (200 ° C.) η = 744 Pa * sec
(Shear rate 100 / sec) Paraffin oil (Diana Process Oil P manufactured by Idemitsu Kosan)
w-380) A rubber roller was produced using the above materials. A raw material mainly composed of the thermoplastic elastomer is used as a twin screw extruder (HTM-38) of an extruder equipped with a die according to the first embodiment.
(Made by IPEC Co., Ltd.)).
The mixture was kneaded while being heated to ° C., and the raw material was extruded into a tube shape from a die to obtain a cylindrical roller having an outer diameter of 30 mm and an inner diameter of 25 mm. Cut this to 15mm in length,
A D-shaped rubber roller was produced by fitting the shaft into a D-shaped shaft core.

(Example 2) The raw materials had the same composition as in Example 1. In the die portion of the extruder, the length of the cylindrical space L = 180 mm and the inner diameter D of the die extrusion port = 30.
mm, L / D = 6. The surface of the mandrel and the inner surface of the die were polished to a surface roughness Ra = 0.5.

(Example 3) The raw materials had the same composition as in Example 1, and the length of the cylindrical space L = 60 mm and the inner diameter D of the die extrusion port = 30 m in the die portion of the extruder.
m, L / D = 2. The surface of the mandrel and the inner surface of the die were polished to a surface roughness Ra = 0.5.

Example 4 The raw materials had the same composition as in Example 1. In the die portion of the extruder, the length of the cylindrical space L was 60 mm, and the inner diameter D of the extrusion port of the die was 30 m.
m, L / D = 2. The surface of the mandrel and the inner surface of the die were polished to have a surface roughness Ra = 6.

Example 5 As a raw material, a styrene-based thermoplastic elastomer SEPS resin (Septon CJ-00) was used.
1 Kuraray Co., Ltd.) was used. Shore hardness Hs = 45 Apparent melt viscosity (200 ° C.) η = 217 Pa * sec
(Shear speed 100 / sec) The length L of the cylindrical space in the mouth portion of the extrusion molding machine
= 120 mm, inner diameter of die extrusion port D = 30 mm, L
/ D = 4. The surface of the mandrel and the inner surface of the die were polished to a surface roughness Ra = 0.5.

Example 6 As a raw material, a rubber material mainly composed of a thermoplastic elastomer obtained by dispersing an EPDM rubber in a mixture of PP (polypropylene) and a styrene-based thermoplastic elastomer was used in the following compounding ratio. . PP / styrene-based thermoplastic elastomer / EPDM = ratio 20/70/100 PP (Novatec PP BC6 manufactured by Nippon Polychem Co., Ltd.) Styrene-based thermoplastic elastomer (Septon 4055 manufactured by Kuraray Co., Ltd.) EPDM (Supremo Chemical Industries, Ltd. Esplen) 670
F) Shore hardness Hs = 55 Apparent melt viscosity (200 ° C.) η = 856 Pa * sec
(Shear rate 100 / sec) Paraffin oil (Diana Process Oil P manufactured by Idemitsu Kosan)
w-380) The amount of paraffin oil is reduced to adjust the Shore hardness Hs. In the die portion of the extruder, the length of the cylindrical space L = 120 mm, and the inner diameter D of the extrusion port of the die = 3.
0 mm and L / D = 4. The surface of the mandrel and the inner surface of the die were polished to a surface roughness Ra = 0.5.

(Comparative Example 1) The raw materials had the same composition as in Example 1. In the die portion of the extruder, the length of the cylindrical space L was 120 mm, and the inner diameter D of the die outlet was 30.
mm, L / D = 4. The surface of the mandrel and the inner surface of the die were kept wire cut (electric discharge machining), and the surface roughness Ra was set to Ra = 10.

(Comparative Example 2) The raw materials had the same composition as in Example 1. In the die portion of the extruder, the length of the cylindrical space L was 30 mm, and the inner diameter D of the die outlet was 30 m.
m, L / D = 1. The surface of the mandrel and the inner surface of the die were polished to a surface roughness Ra = 0.5.

Comparative Example 3 As a raw material, a styrene-based thermoplastic elastomer SEPS resin (Septon SC-66) was used.
9 (Kuraray Co., Ltd.). Shore hardness Hs = 20 Apparent melt viscosity (200 ° C.) η = 100 Pa * sec
(Shear speed 100 / sec) The length L of the cylindrical space in the mouth portion of the extrusion molding machine
= 120 mm, inner diameter of die extrusion port D = 30 mm, L
/ D = 4. The surface of the mandrel and the inner surface of the die are kept as wire cut (electric discharge machining), and the surface roughness Ra = 1
0 was set.

In the rubber rollers manufactured in Examples 1 to 6 and Comparative Examples 1 to 3, first, a rubber roller 500 m was visually observed.
The surface for m minutes was observed, and the presence or absence of Sasakure was confirmed. Next, the surface of the rubber roller for 100 mm was observed with a stereoscopic microscope, and the presence or absence of sasare was confirmed.
It was set to K. The above observation results are shown in Table 1 above.

As shown in Table 1, it was confirmed that the rubber rollers of Examples 1 to 6 did not generate rust on the surface and that a rubber roller having a good surface condition was obtained. Also,
In the rubber rollers of Comparative Examples 1 and 2, rust was generated on the surface, and the surface skin was rough. Since the rubber roller of Comparative Example 3 had low viscosity, the extrusion tube was crushed and deformed.

[0046]

As is apparent from the above description, when a rubber roller is formed by using the manufacturing apparatus of the present invention, the ratio L of the length L of the extrusion space of the die portion of the extruder to the inner diameter D of the die is obtained. / D is 2 or more and the surface roughness Ra of the mandrel surface and the inner surface of the die is 6 μm or less. Therefore, even if extrusion molding is performed using a raw material mainly composed of a high-viscosity thermoplastic elastomer, Since the resistance at the time of extruding is reduced, it is easy to extrude, and extrusion molding can be performed without roughening the surface.

Therefore, it is possible to suppress the occurrence of creaking on the surface of the formed rubber roller, and to obtain a rubber roller having a smooth surface and a high friction coefficient on the surface of the rubber roller. The polishing process can be reduced, and the manufacturing process of the rubber roller can be simplified. Furthermore, since the material is extruded through the space between the die and the mandrel at the die portion of the material extrusion molding, the dimensional accuracy of the formed roller can be improved. That is, since the vulcanizing step using a vulcanizer, which is required when a conventional rubber material is used, is eliminated, dimensional accuracy is improved, and a high quality rubber roller can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view of a rubber roller manufactured by a rubber roller manufacturing apparatus according to the present invention.

FIG. 2 is a schematic diagram showing a state in which the rubber roller is applied to a printer.

FIG. 3 is an overall schematic view of a rubber roller manufacturing apparatus of the present invention.

FIG. 4A is a front view of a mandrel used for a base part, FIG. 4B is a cross-sectional view of a die, and FIG. 4C is a cross-sectional view of a state where the mandrel and the die are fitted.

FIGS. 5A and 5B are cross-sectional views showing a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rubber roller 2 Shaft core 11 Extruder 12 Mandrel 12b Straight part 13 Die 13b Straight part 20 Cylindrical space

Claims (1)

[Claims] 1. A raw material containing a thermoplastic elastomer as a main component is extruded into a tubular space defined by an inner mandrel and an outer die in a die portion of an extruder, and a predetermined length is extruded. A rubber roller manufacturing apparatus manufactured by cutting into a hollow portion and inserting a shaft core into a hollow portion, wherein a length L of a straight portion in a longitudinal direction of a cylindrical space formed by the mandrel and the die, and a length of the die An apparatus for manufacturing a rubber roller, wherein the value of the ratio L / D to the inner diameter D is 2 or more, and the value of the surface roughness Ra of the outer surface of the mandrel and the inner surface of the die is 6 μm or less.