JP2002179263A - Paper feed roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feed roller 1 having a high coefficient of friction with a paper sheet and an excellent wear resistance and, accordingly, capable of developing an excellent transfer force over a long period of time. SOLUTION: A core 2 is inserted into a paper feed roller 1. The paper feed roller 1 is formed by bridging a rubber composition. The rubber composition includes a base material rubber and ultrahigh molecular weight polyethylene. The mixed ratio of the ultrahigh molecular weight polyethylene is 5 to 50 parts against the base material rubber of 100 parts, particularly, 10 to 40 parts. The base material rubber is composed mainly of an ethylene-propylene-diene copolymer. The weight-average molecular weight of the ultrahigh molecular weight polyethylene is 1 million or more, particularly 1 million and 800 thousand or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feed roller mounted on office equipment or the like and contributing to the transport of paper.

[0002]

2. Description of the Related Art Copiers, facsimile machines, printers, A
A paper feed roller (referred to as a paper feed roller, a transport roller, a paper discharge roller, or the like) is used for a paper feed mechanism, an image forming mechanism, a fixing mechanism, a paper discharge mechanism, and the like of office equipment such as a TM. . Since the paper feed roller feeds paper, it is required that the friction coefficient with paper be high, and that this high friction coefficient be maintained for a long time.

Usually, the paper feed roller is made of crosslinked rubber. As the rubber to be used, natural rubber, ethylene-propylene-diene copolymer (EPDM), urethane rubber, silicone rubber, polynorbornene and the like are generally used. The use of these rubbers imparts flexibility to the paper feed roller and increases the coefficient of friction with paper.

[0004] The rubber paper feed roller does not have sufficient abrasion resistance. Therefore, the surface gradually wears due to continuous contact with the paper, and the paper may not be able to be conveyed soon. ).

A paper feed pinch roll having an outer layer made of ultra-high molecular weight polyethylene (JP-A-10-25087)
No. 0) or a feed roller provided with a coating layer made of a synthetic resin containing ultra-high molecular weight polyethylene particles (Japanese Patent Application Laid-Open No.
No. 43176) has also been proposed. Since ultrahigh molecular weight polyethylene has excellent wear resistance, its use improves the wear resistance of the paper feed roller.

[0006] However, layers made of ultra-high molecular weight polyethylene generally have high hardness. Therefore, in the paper feed roller in which the surface in contact with the paper is a layer made of ultra-high molecular weight polyethylene, the coefficient of friction with the paper tends to be low from the new stage, and the conveying force tends to be insufficient.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing problems, and has a high coefficient of friction with paper, excellent abrasion resistance, and therefore, has an excellent conveying force over a long period of time. The purpose of the present invention is to provide a paper feed roller.

[0008]

Means for Solving the Problems The invention made to achieve the above object is to provide a base rubber and a base rubber 100
A paper feed roller formed by crosslinking a rubber composition containing 5 parts or more and 50 parts or less of ultra-high molecular weight polyethylene per part,
It is.

This paper feed roller has a high coefficient of friction with paper since the main component is rubber. Further, since this paper feed roller contains ultrahigh molecular weight polyethylene, it has excellent wear resistance. That is, the paper feed roller has both a high coefficient of friction with paper and excellent wear resistance. With this paper feed roller, excellent conveyance force is maintained for a long period of time.

[0010] Preferably, ultrahigh molecular weight polyethylene having a weight average molecular weight of 1.8 million or more is used. Thereby, the wear resistance of the paper feed roller is further enhanced.

Preferably, the base rubber contains an ethylene-propylene-diene copolymer as a main component. The ethylene-propylene-diene copolymer is a rubber having excellent weather resistance. The use of the ethylene-propylene-diene copolymer, combined with the incorporation of ultra-high molecular weight polyethylene, suppresses the time-dependent change in the properties of the paper feed roller.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
The present invention will be described in detail based on embodiments.

FIG. 1 is a perspective view showing a paper feed roller 1 as a paper feed roller according to an embodiment of the present invention, together with a shaft core 2. The paper feed roller 1 is formed by molding and crosslinking a rubber composition. The paper feed roller 1 is fixed to the shaft core 2 by press-fitting the paper feed roller 1 into the shaft core 2 or by bonding them with an adhesive. The thickness of the paper feed roller 1 is usually 1 mm to 8 mm, particularly 2 mm to 5 mm. Further, the overall length of the paper feed roller 1 is usually set to 10 mm to 20 mm.

The base rubber of the rubber composition includes ethylene-propylene-diene copolymer, silicone rubber, urethane rubber, polynorbornene, chlorinated polyethylene, polyisoprene, polybutadiene, styrene-butadiene copolymer, natural rubber, etc. Can be used. Two or more of these rubbers may be used in combination.

A particularly preferred rubber is an ethylene-propylene-diene copolymer. Since the main chain of the ethylene-propylene-diene copolymer is composed of a saturated hydrocarbon, this main chain does not contain a double bond. For this reason, even if the ethylene-propylene-diene copolymer is exposed to an environment such as a high-concentration ozone atmosphere or light irradiation for a long time, the molecular main chain is hardly broken (that is, excellent in weather resistance). Therefore, good conveying force is maintained for a long time in combination with the ultrahigh molecular weight polyethylene described later. In a copier or the like, ozone may be generated at the time of image formation. Even in this case, the ozone deterioration of the feed roller 1 is suppressed by using the ethylene-propylene-diene copolymer.

An ethylene-propylene-diene copolymer may be used in combination with another rubber for the purpose of improving the strength of the paper feed roller 1 and improving the workability. Even in this case, it is preferable that the ethylene-propylene-diene copolymer be the main component from the viewpoint of the weather resistance of the paper feed roller 1. Specifically, the proportion of the ethylene-propylene-diene copolymer in the total base rubber is preferably 50% by mass or more, particularly preferably 80% by mass or more, and ideally 100% by mass. It is.

As the ethylene-propylene-diene copolymer, there are a non-oil-extended type composed of only a rubber component and an oil-extended type containing an extending oil together with a rubber component. Either type can be used.
When an oil-extended ethylene-propylene-diene copolymer is used, the ratio of the rubber component excluding the extender oil to the total base rubber is within the above range (50% by mass or more, particularly 80% by mass). Mass% or more, ideally 100 mass%)
What should be done.

As the ethylene-propylene-diene copolymer, a polymer obtained by polymerization with a metallocene catalyst (so-called "metallocene EPDM") may be used. Metallocene EPDM has a narrower molecular weight distribution and a more uniform monomer distribution than an ethylene-propylene-diene copolymer polymerized with a Ziegler-Natta catalyst.
By using this metallocene EPDM, the abrasion resistance of the paper feed roller 1 is improved. Therefore, in combination with the ultrahigh molecular weight polyethylene described later, the feed roller 1
Good conveying force is maintained for a long time.

The rubber composition contains ultrahigh molecular weight polyethylene. Ultra high molecular weight polyethylene is AS
It is a polyethylene having a weight average molecular weight of 500,000 or more measured according to TM-D-4020. Ultra-high molecular weight polyethylene is excellent in mechanical strength because of its high molecular weight. By including ultrahigh molecular weight polyethylene, the abrasion resistance of the feed roller 1 is improved.

The compounding amount of the ultrahigh molecular weight polyethylene is 5 parts or more and 50 parts or less based on 100 parts of the base rubber. If the amount is less than 5 parts, the abrasion resistance of the paper feed roller 1 may be insufficient. In this respect, the amount is preferably equal to or greater than 10 parts, and particularly preferably equal to or greater than 15 parts. Conversely, if the compounding amount exceeds 50 parts, the processability (kneading property, moldability, etc.) in the manufacturing process of the paper feed roller 1 may be deteriorated.
In this respect, the amount is preferably equal to or less than 40 parts, and particularly preferably equal to or less than 35 parts. In addition, in this specification, the numerical value shown by "part" means a ratio based on mass.

It is preferable to blend ultrahigh molecular weight polyethylene having a weight average molecular weight of 1,000,000 or more, more preferably ultrahigh molecular weight polyethylene having a weight average molecular weight of 1.8 million or more, and 5,000,000 or more. It is particularly preferred that the above ultrahigh molecular weight polyethylene is blended. As the weight average molecular weight is higher, the wear resistance of the paper feed roller 1 is improved. Also, as the weight average molecular weight is higher, the blending amount of ultra-high molecular weight polyethylene can be set smaller,
Workability can be improved. There is no particular upper limit on the weight average molecular weight, but the ultra high molecular weight polyethylene usually obtained has a weight average molecular weight of 7,000,000 or less.

[0022] Other thermoplastic polymers may be blended with the ultra-high molecular weight polyethylene. Examples of the thermoplastic polymer that can be blended include polyethylene other than ultrahigh molecular weight polyethylene, polypropylene, ionomer resin, polyamide, polystyrene, polycarbonate, polyacetal, acrylic resin, and a thermoplastic elastomer having a soft segment and a hard segment.

The form of cross-linking of the paper feed roller 1 is not particularly limited, but when an ethylene-propylene-diene copolymer is the main component of the base rubber, sulfur cross-linking is usually used, and the cross-linking is carried out together with sulfur. A sulfur accelerator is used in combination. In this case, the compounding amount of sulfur is 0.5 part with respect to 100 parts of the base rubber.
Not less than 4.0 parts by weight. In addition, the compounding amount of the vulcanization accelerator is 1.0 part or more and 7.0 parts with respect to 100 parts of the base rubber.
Parts or less are preferred. If the amount of the sulfur or the vulcanization accelerator is less than the above range, the strength of the feed roller 1 may be insufficient. Conversely, if the amount of sulfur or the vulcanization accelerator exceeds the above range, the coefficient of friction between the paper feed roller 1 and the paper may decrease.

The rubber composition may contain a filler. The hardness, friction coefficient, surface roughness and the like of the paper feed roller 1 can be adjusted by the filler. Preferred fillers include, for example, silicon oxide, calcium carbonate, titanium oxide and the like. The preferred compounding amount of the filler depends on the kind thereof, but is usually 10 parts or more to 100 parts of the base rubber.
0 parts or less, especially 20 parts or more and 40 parts or less.

The rubber composition may contain a softener such as an oil or a plasticizer. As a result, the paper feed roller 1 has low hardness and its friction coefficient is improved. Examples of the oil to be blended include paraffinic mineral oil, naphthenic mineral oil, aromatic mineral oil, and hydrocarbon oligomer. Examples of the plasticizer to be blended include dioctyl phthalate, dibutyl phthalate, dioctyl sepate, dioctyl adipate, and the like. When an oil-extended rubber is used, the extension oil acts as a softening agent, so that the blending of another softening agent may be omitted.
Of course, if necessary, a softening agent may be further added to the oil-extended type rubber.

Additives such as a reinforcing agent such as carbon black, a crosslinking assistant, a coloring agent, and a deterioration inhibitor may be added to the rubber composition in an appropriate amount, if necessary.

In the manufacture of the feed roller 1, first, a base rubber,
Ultra-high molecular weight polyethylene, a cross-linking agent, various additives and the like are charged into a kneader and kneaded. Preferred kneading machines include:
An internal mixer such as a kneader or a Banbury mixer may be used. Next, the rubber composition obtained by kneading is put into a mold and molded and cross-linked under pressure. As shown in FIG. 1, the paper feed roller 1 has a cylindrical shape, and therefore a core (mandrel) is provided in a mold. Of course, a molding method such as an injection molding method may be adopted. After the molding, the molded product is cut into a predetermined size, and the paper feed roller 1 is obtained. The surface of the molded article may be polished for the purpose of adjusting the surface roughness or the like. The shaft core 2 is mounted on the paper feed roller 1 and used in a paper feed mechanism.

FIG. 2 is a schematic sectional view showing a sheet feeding mechanism 3 using the sheet feeding roller 1 of FIG. The paper feed mechanism 3 includes a separation pad 4 and a tray 5 in addition to the paper feed roller 1.
Etc. are provided. The separation pad 4 and the tray 5 are separated. The separation pad 4 is fixed to the substrate 6 and faces the paper feed roller 1. The paper feed roller 1 has an arrow R in the figure.
The paper 7 on the tray 5 is sent out one by one by rotating in the direction indicated by. The paper is conveyed to the image forming mechanism and the fixing mechanism and discharged. A transport roller is used for the transport. A paper discharge roller is used for discharging. By using the same rubber composition as the paper feed roller 1 for the transport roller and the paper discharge roller, a high friction coefficient and good wear resistance of these rollers can be achieved. That is, the paper feed roller of the present invention includes, in addition to the paper feed roller 1, a roller that contributes to the paper conveyance, such as a conveyance roller and a paper discharge roller.

[0029]

EXAMPLES Hereinafter, the effects of the present invention will be clarified based on examples, but the present invention should not be construed as being limited based on the description of the examples.

[Example 1] 200 parts of an ethylene-propylene-diene copolymer (trade name "Esprene 670F" manufactured by Sumitomo Chemical Co., Ltd.) with 100% oil extension (rubber component: 100 parts), weight average molecular weight of more than 2,000,000 5 parts of high molecular weight polyethylene (trade name “Miperon XM-220” of Mitsui Chemicals, Inc.), silicon oxide (trade name “Nipsil VN” of Nippon Silica Co., Ltd.)
3 ") 5 parts, calcium carbonate (Bihoku Powder Chemical Co., Ltd. product name" B
F300 ") 10 parts, titanium oxide (trade name" Kronos titanium oxide KR380 "of Titanium Industry Co., Ltd.) 10 parts, paraffin oil (trade name" PW-90 "of Idemitsu Kosan Co., Ltd.) 30
Parts, 3 parts of carbon black (trade name “SEIST SO” of Tokai Carbon Co., Ltd.), 5 parts of zinc oxide (trade name of “2 kinds of zinc oxide” of Mitsui Kinzoku Co., Ltd.), and stearic acid (trade name of “Tsubaki” of NOF Corporation) ) 1 part, sulfur (Tsurumi Chemical's powdered sulfur) 2
Part, dibenzothiazyl sulfide as vulcanization accelerator (trade name “Noxeller DM” of Ouchi Shinko Chemical Co., Ltd.) 1
Parts and 3 parts of tetraethylthiuram disulfide (trade name “Noxeller TET” of Ouchi Shinko Chemical Co., Ltd.) as a vulcanization accelerator were charged into a closed kneader and kneaded to obtain a rubber composition.

The rubber composition is charged into a mold and heated at 170 ° C.
And heat for 20 minutes to crosslink the rubber and cylindrical body (cot)
Was molded. The inner diameter of this cylinder was 9 mm, the outer diameter was 21 mm, and the length was 38 mm. The outer peripheral surface of the cylindrical body was ground with a cylindrical grinder until the outer peripheral diameter became 20 mm, and was further cut into a length of 10 mm to obtain a feed roller of Example 1.

Example 2 A sheet feed roller of Example 2 was obtained in the same manner as in Example 1 except that the amount of the ultrahigh molecular weight polyethylene was varied as shown in Table 1 below.

Comparative Example 1 Comparative Example 1 was carried out in the same manner as in Example 1 except that no ultrahigh molecular weight polyethylene was blended.
Was obtained.

Comparative Example 2 An attempt was made to obtain a paper feed roller in the same manner as in Example 1 except that the amount of the ultrahigh molecular weight polyethylene was varied as shown in Table 1 below, but kneading was not possible. Was. Subsequent evaluations were discontinued.

Example 3 The procedure of Example 1 was repeated, except that 20 parts of ultrahigh molecular weight polyethylene having a weight average molecular weight of 6,000,000 (trade name of “HIZEX Million 630M” of Mitsui Chemicals, Inc.) were used. Thus, a paper feed roller of Example 3 was obtained.

Comparative Example 3 The same as Example 1 except that ultrahigh molecular weight polyethylene was not blended and 20 parts of polyethylene having a weight average molecular weight of 50,000 (trade name "Ultzex 2005HC" of Mitsui Chemicals, Inc.) was blended. Thus, a paper feed roller of Comparative Example 3 was obtained.

[Measurement of Initial Friction Coefficient] Plain paper ("P paper" manufactured by Fuji Xerox Co., Ltd.) was prepared, and was 60 mm long and 2 mm wide.
It was cut into a 10 mm rectangle to obtain a measurement paper 9. This measurement paper 9 is sandwiched between the paper feed roller 1 and the Teflon (registered trademark) plate 8 as shown in FIG.
The feed roller 1 was pressed against the Teflon plate 8 by applying a load W of 50 gf. Next, the paper feed roller 1 was rotated in the direction indicated by the arrow R at a peripheral speed of 300 mm / sec. Then, with the load cell 10 connected to one end of the measurement paper 9,
The force (gf) generated in the direction indicated by arrow F in FIG. 3 was measured. The value obtained by dividing the force F by the load W was obtained and used as an initial friction coefficient. The measurement was performed at a temperature of 23 ° C. and a humidity of 55%. The results are shown in Table 1 below.

[Measurement of Amount of Abrasion] Three paper feed rollers were prepared and arranged as a feed roller 11, a retard roller 12, and a pickup roller 13 as shown in FIG. The distance between the feed roller 11 and the pickup roller 13 (indicated by a double-headed arrow L in FIG. 4) was 36 mm. A4 between the pickup roller 13 and the base 14
Size plain paper 15 (the above-mentioned “P paper”) is sandwiched, and a vertical downward load (250
gf). Also, the axis of the retard roller 12 is
A vertically upward load (250 gf) was applied. Then, the reverse torque of the retard roller 12 is set to 240 gf · cm,
The feed roller 11 and the pickup roller 13 were rotated at a peripheral speed of 300 mm / sec in the direction indicated by the arrow R, and the plain paper 15 was sent out to the right. The mass of the retard roller 12 after sending out 50,000 sheets of plain paper 15 was measured, and this was subtracted from the mass before sending out to calculate the wear amount of the retard roller 12. The results are shown in Table 1 below.

[Paper-passing test] A paper feed roller was mounted on a copying machine (trade name "VIVACE455" of Fuji Xerox Co., Ltd.). Then, under conditions of a temperature of 23 ° C. and a humidity of 55%, A4
50,000 sheets of plain paper of the size (the aforementioned “P paper”) were passed, and the passing status in the latter half of the passing was checked. A case where no conveyance failure occurred was indicated by “と し”, a case where slight non-feeding occurred was indicated by “△”, and a case where non-delivery occurred frequently was indicated by “×”. The results are shown in Table 1 below.

[0040]

[Table 1]

Table 1 shows that the abrasion loss of the feed rollers of Comparative Examples 1 and 3 in which no ultrahigh molecular weight polyethylene was blended was large. Such a paper feed roller having poor abrasion resistance tends to cause paper non-feeding. On the other hand, the feed roller of each embodiment in which ultra-high molecular weight polyethylene is blended has a small wear amount and no non-feeding is observed. From these evaluation results, the superiority of the present invention is apparent.

[0042]

As described above, the paper feed roller of the present invention has excellent abrasion resistance, and the coefficient of friction with paper hardly decreases even when used. With this paper feed roller, a good conveying force is maintained for a long period of time.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a paper feed roller as a paper feed roller according to an embodiment of the present invention together with a shaft core.

FIG. 2 is a schematic cross-sectional view illustrating a paper feed mechanism using the paper feed roller of FIG. 1;

FIG. 3 is a schematic front view illustrating a state of measuring a friction coefficient of a sheet feeding roller.

FIG. 4 is a schematic front view showing a state of measuring a wear amount of a sheet feeding roller.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Paper feed roller 2 ... Shaft core 3 ... Paper feed mechanism 4 ... Separation pad 5 ... Tray 6 ... Substrate 7 ... Paper 8 ... Teflon plate 9 ...・ Measurement paper 10 ・ ・ ・ Load cell 11 ・ ・ ・ Feed roller 12 ・ ・ ・ Retard roller 13 ・ ・ ・ Pickup roller 14 ・ ・ ・ Base

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // (C08L 21/00 (C08L 21/00 23:04) 23:04) F-term (Reference) 2C059 CC15 CC25 3F049 CA12 CA15 CA16 LA02 LA05 LA07 LB03 3F343 FA01 FB02 FB03 FB04 FC23 GB01 JA01 JA11 4J002 AC011 AC031 AC061 AC081 BB032 BB151 BB241 CE001 CK021 CP031 FD020 GM00

Claims (3)

[Claims] 1. A paper feed roller formed by crosslinking a rubber composition containing a base rubber and 5 to 50 parts of ultrahigh molecular weight polyethylene based on 100 parts of the base rubber. 2. The paper feed roller according to claim 1, wherein the ultrahigh molecular weight polyethylene has a weight average molecular weight of 1.8 million or more. 3. The paper feed roller according to claim 1, wherein a main component of the base rubber is an ethylene-propylene-diene copolymer.