Paper feeding roller and electrophotographic apparatus or dedicated scanner

Abstract

To provide a paper feeding roller exhibiting superior resistance to swelling with respect to both aromatic petroleum-based oils and higher fatty acid esters.SOLUTION: A paper feeding roller includes a shaft body and an elastic layer disposed around the shaft body, wherein the elastic layer is composed of a polyurethane rubber composition containing a polymer component and a curing agent component, the polymer component includes an ester-based polyurethane (A) and an ether-based polyurethane (B), a weight ratio of the ester-based polyurethane (A) to the ether-based polyurethane (B) is (A) / (B)=90 / 10-60 / 40, the durometer hardnesses of the ester-based polyurethane (A) and the ether-based polyurethane (B) are both 65°-95°, the curing agent component is an amine-based curing agent component (C), and the durometer hardness of the elastic layer is 75°-95°.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a paper feed roller and an electrophotographic apparatus or dedicated scanner. [Background technology]

[0002] In electrophotographic devices such as multifunction devices equipped with multiple functions such as a printer, copier, scanner, and fax machine, or dedicated scanner devices, a paper feed roller is used in the transport mechanism for transporting paper-like objects such as paper or film into the device. The paper feed roller conveys paper or the like by rotating while holding the paper or the like by frictional force.

[0003] Traditionally, ethylene propylene diene (EPDM) rubber has been widely used as the material for the elastic layer of paper feed rollers due to its cost. However, EPDM rubber is susceptible to ink and toner penetration and has poor swelling resistance. Furthermore, in recent years, low-melting-point toners containing low-melting-point waxes with melting points of 70°C to 100°C, which can be fixed at low temperatures, have been used to reduce the energy consumption of electrophotographic devices. Therefore, when a paper feed roller with an EPDM rubber elastic layer is used in an electrophotographic device, problems such as poor paper feed and paper jams can occur.

[0004] Therefore, paper feed rollers using polyurethane rubber, silicone rubber, or the like as the material for the elastic layer instead of EPDM rubber have come to be used. However, silicone rubber had problems such as wear when paper was fed over long distances, and its durability was inferior to that of urethane rubber in high-speed machines.

[0005] Patent Document 1 proposes a paper feed roller using a urethane rubber composition. It is described that this paper feed roller has excellent swelling resistance and is able to suppress swelling caused by paraffin wax, but it does not mention its resistance to plasticizers used in scanners. Furthermore, the addition of a filler to the urethane rubber composition reduces the rubber elasticity inherent to rubber and also reduces durability.

[0006] Carbonless paper is also used for copying slips and documents, and contains microcapsules containing color formers. When writing on the carbonless paper with a ballpoint pen or other device, pressure is applied, which breaks the microcapsules and releases the color former. The released color former reacts chemically with the developer applied to the copying surface, causing color to be released, allowing the characters written on the surface of the carbonless paper to be copied.

[0007] The microcapsules in carbonless paper contain oil such as a high-boiling solvent to efficiently transfer the color former when the microcapsules are broken. When carbonless paper is passed through an electrophotographic device, the oil seeps out of the microcapsules and penetrates the paper feed roller, causing the roller to swell and resulting in problems such as poor paper feed and paper jams.

[0008] Until now, non-polar oils such as phenylxylylethane (PXE), a petroleum-based diallylalkane oil, have been mainly used as the oil for microcapsules. However, in recent years, there has been a trend to avoid the use of such aromatic petroleum-based oils, and carbonless paper using vegetable oil-based higher fatty acid esters has been proposed.

[0009] In Patent Document 2, the swelling resistance of polyurethane to PXE, which is a capsule oil contained in carbonless paper, is evaluated, but swelling resistance to vegetable oil-based higher fatty acid esters is not examined. The polyurethane composition described in Patent Document 2 has an SP value close to that of higher fatty acid esters, and is therefore thought to have low swelling resistance to higher fatty acid esters. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent No. 5399369 [Patent Document 2] Patent No. 6545937 Summary of the Invention [Problem to be solved by the invention]

[0011] Under these circumstances, there is a demand for a paper feed roller that is highly resistant to swelling caused by both aromatic petroleum oils and higher fatty acid esters.

[0012] An object of the present invention is to provide a paper feed roller that is excellent in resistance to swelling caused by both aromatic petroleum oils and higher fatty acid esters. [Means for solving the problem]

[0013] That is, the present invention (1) is a paper feed roller comprising a shaft and an elastic layer arranged around the shaft, wherein the elastic layer is made of a polyurethane rubber composition containing a polymer component and a curing agent component, the polymer component contains an ester-based polyurethane (A) and an ether-based polyurethane (B), the weight ratio of the ester-based polyurethane (A) to the ether-based polyurethane (B) is (A) / (B) = 90 / 10 to 60 / 40, the durometer hardnesses of the ester-based polyurethane (A) and the ether-based polyurethane (B) are both 65° to 95°, the curing agent component is an amine-based curing agent component (C), and the durometer hardness of the elastic layer is 75° to 95°.

[0014] In the paper feed roller of the present invention, the polyurethane rubber composition constituting the elastic layer has a durometer hardness of 75° to 95° and exhibits excellent swelling resistance to both aromatic petroleum-based oils and higher fatty acid esters. Furthermore, since the ester-based polyurethane (A) and the ether-based polyurethane (B) have durometer hardnesses of 65° to 95° so that the polyurethane rubber composition has a durometer hardness of 75° to 95°, there is no need to use a filler to increase the durometer hardness of the polyurethane rubber composition. This is preferable because, unlike polyurethane rubber compositions in which the durometer hardness is increased using a filler, there is no decrease in rubber elasticity or durability.

[0015] Furthermore, by setting the weight ratio of the ester-based polyurethane (A) to the ether-based polyurethane (B) to (A) / (B) = 90 / 10 to 60 / 40, it is possible to achieve a high degree of both the oil resistance of the ester-based polyurethane and the hydrolysis resistance of the ether-based polyurethane.

[0016] The present invention (2) is the paper-feeding roller according to the present invention (1), wherein the polyurethane rubber composition does not contain silica as a filler. The polyurethane rubber composition constituting the paper feed roller of present invention (2) is preferable because, unlike polyurethane rubber compositions in which silica is used as a filler to increase the durometer hardness, there is no decrease in rubber elasticity or durability.

[0017] The present invention (3) is the paper-feeding roller according to the present invention (1) or (2), wherein the polyurethane rubber composition is a cast urethane rubber. Cast urethane rubber is a urethane rubber produced by heating and mixing a urethane prepolymer, which has been previously reacted with an isocyanate and a polyol, with a curing agent, and then pouring the resulting liquid into a heated mold to form the mold. The molds and equipment used to manufacture cast urethane rubber are inexpensive, can be molded into complex shapes, are easy to post-process, and have stable quality.

[0018] The present invention (4) is the paper-feeding roller according to any one of the present inventions (1) to (3), wherein the amine-based curing agent component (C) is an aromatic diamine. When the amine-based curing agent component (C) is an aromatic diamine, the mechanical properties and rubber elasticity of the polyurethane rubber composition can be improved.

[0019] The present invention (5) is an electrophotographic device or a dedicated scanner that can transport carbonless paper using the paper feed roller according to any one of the present inventions (1) to (4). The paper feed roller of the present invention has excellent resistance to swelling caused by both aromatic petroleum oils and higher fatty acid esters, and is therefore suitable for use in electrophotographic devices capable of transporting carbonless paper. In addition, dedicated scanner machines are sometimes used to scan large quantities of carbonless paper at high speeds, and the paper feed roller of the present invention has excellent swelling resistance to both aromatic petroleum-based oils and higher fatty acid esters, making it particularly suitable for use in dedicated scanner machines that scan large quantities of carbonless paper at high speeds.

[0020] The present invention (6) is the electrophotographic apparatus or dedicated scanner according to the present invention (5), wherein the microcapsules of the carbonless paper contain aromatic petroleum oil and / or higher fatty acid ester. [Effects of the Invention]

[0021] According to the present invention, it is possible to provide a paper feed roller that has excellent resistance to swelling caused by both aromatic petroleum oils and higher fatty acid esters. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a perspective view schematically illustrating an example of a paper feed roller. [Figure 2] FIG. 2 is a flow diagram showing the manufacturing process of cast urethane rubber. DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention will be described in detail below. However, the present invention is not limited to the following embodiments, and can be appropriately modified and applied within the scope of the present invention.

[0024] The paper feed roller of the present invention is a paper feed roller comprising a shaft and an elastic layer arranged around the shaft, wherein the elastic layer is made of a polyurethane rubber composition containing a polymer component and a curing agent component, the polymer component includes an ester-based polyurethane (A) and an ether-based polyurethane (B), the weight ratio of the ester-based polyurethane (A) to the ether-based polyurethane (B) is (A) / (B) = 90 / 10 to 60 / 40, the durometer hardnesses of the ester-based polyurethane (A) and the ether-based polyurethane (B) are both 65° to 95°, the curing agent component is an amine-based curing agent component (C), and the durometer hardness of the elastic layer is 75° to 95°.

[0025] A paper feed roller is a roller that transports paper, film, etc., and is a general term for paper feed rollers, paper discharge rollers, transport rollers, reversing rollers, driven rollers, etc. in electrophotographic devices and dedicated scanners, as well as transport rollers in transport devices.

[0026] FIG. 1 is a perspective view schematically illustrating an example of a paper feed roller. The paper feed roller 1 shown in FIG. 1 includes a shaft body 10 and an elastic layer 20 arranged around the shaft body 10.

[0027] The shaft body is a shaft that rotatably supports the paper feed roller. The material of the shaft body is preferably a conductive metal. Examples of metals that can be used include iron, stainless steel copper, and aluminum alloys. These metals can also be plated using electrolytic or electroless plating. Examples of materials other than metals include acrylonitrile butadiene styrene copolymer, polycarbonate, polyacetal, and polyurethane. The length and thickness of the shaft are not particularly limited, and are designed to match the size of the device in which the paper feed roller is disposed.

[0028] The elastic layer is the part of the paper feed roller that comes into direct contact with the paper being conveyed, and is a layer that exhibits the properties required of a paper feed roller, such as surface hardness and frictional force. The elastic layer is disposed around the shaft body. The entire periphery of one shaft may be covered with an elastic layer, or a plurality of elastic layers may be provided at separate positions on one shaft. The materials constituting the elastic layer will be described in detail below.

[0029] The elastic layer is made of a polyurethane rubber composition containing a polymer component and a curing agent component. The polymer component includes an ester-based polyurethane (A) and an ether-based polyurethane (B).

[0030] The ester-based polyurethane (A) is a polyurethane obtained by a urethane reaction between a polyester polyol and a polyisocyanate. Examples of polyester polyols include polycondensed polyester polyols obtained from dibasic acids and glycols, and polycaprolactone polyols obtained by ring-opening polymerization of ε-caprolactone. Examples of dibasic acids include succinic acid, glutaric acid, adipic acid, pimelic acid, diglycolic acid, oxybismethylenebisacetic acid, isophthalic acid, terephthalic acid, etc. Examples of glycols include ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, trimethylolpropane, neopentyl glycol, etc. Among these, polycondensation polyester polyols are preferred from the viewpoints of excellent oil resistance and cost.

[0031] Examples of polyisocyanates include aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates. Examples of aromatic polyisocyanates include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), xylylene diisocyanate (XDI), and phenylene diisocyanate. Examples of aliphatic polyisocyanates include hexamethylene diisocyanate (HDI), and examples of alicyclic polyisocyanates include isophorone diisocyanate (IPDI), hydrogenated xylylene diisocyanate (hydrogenated XDI), and dicyclohexylmethane diisocyanate (hydrogenated MDI). Of these polyisocyanates, TDI is preferred.

[0032] The ether-based polyurethane (B) is a polyurethane obtained by a urethane reaction between a polyether polyol and a polyisocyanate. Examples of polyether polyols include polyols with ether bonds in the main chain, such as polyoxypropylene glycol (PPG) and polyoxytetramethylene glycol (PTMG). Polyurethanes using PTMG are preferred because they have better mechanical strength, abrasion resistance, and hydrolysis resistance than polyurethanes using PPG. On the other hand, PPG has the advantage of being versatile and available in a wide variety of types.

[0033] As the polyisocyanate constituting the ether-based polyurethane (B), the same polyisocyanate as the polyisocyanate constituting the ester-based polyurethane (A) can be used. The polyisocyanate constituting the ester polyurethane (A) and the polyisocyanate constituting the ether polyurethane (B) may be the same or different.

[0034] Ester-based polyurethane (A) has high strength and excellent oil resistance, but is poor in hydrolysis resistance. The ether-based polyurethane (B) has excellent hydrolysis resistance, but is poor in oil resistance. The weight ratio of the ester-based polyurethane (A) to the ether-based polyurethane (B) contained in the polymer component is (A) / (B) = 90 / 10 to 60 / 40. By setting the weight ratio in this manner, the respective characteristics of the ester-based polyurethane (A) and the ether-based polyurethane (B) can be appropriately exhibited, and an elastic layer having an excellent balance of strength, oil resistance, and hydrolysis resistance can be formed.

[0035] The durometer hardness of both the ester polyurethane (A) and the ether polyurethane (B) is 65° to 95°. In this specification, the durometer hardness is the durometer A hardness determined in accordance with JIS K 6253-3 (2012) "Vulcanized rubber and thermoplastic rubber - Determination of hardness - Part 3: Durometer hardness."

[0036] The durometer hardness of the ester polyurethane (A) and the ether polyurethane (B) may be the same or different. When they are different, the durometer hardness of the ester polyurethane (A) may be higher than that of the ether polyurethane (B), or the durometer hardness of the ether polyurethane (B) may be higher than that of the ester polyurethane (A).

[0037] When a prepolymer is used, the durometer hardness of each of the ester-based polyurethane (A) and the ether-based polyurethane (B) is the durometer hardness of the ester-based polyurethane (A) and the ether-based polyurethane (B) cured using 3,3'-dichloro-4,4'-diaminodiphenylmethane as a curing agent. If the prepolymer composition of the ester-based polyurethane (A) and the ether-based polyurethane (B) contained in the elastic layer is known, the durometer hardness can be adjusted by producing a cured product by curing the ester-based polyurethane (A) and the ether-based polyurethane (B) with the same composition.

[0038] The durometer hardness of the elastic layer is 75° to 95°. The durometer hardness of the elastic layer is the durometer hardness of the elastic layer obtained by curing the ester-based polyurethane (A) and the ether-based polyurethane (B) with the curing agent component. The durometer hardness of the elastic layer is relatively high, and the high hardness of the elastic layer makes it possible to provide excellent oil resistance (swelling resistance) to both aromatic petroleum oils and higher fatty acid esters.

[0039] Furthermore, since the ester-based polyurethane (A) and the ether-based polyurethane (B) have a durometer hardness of 65° to 95° (the raw polyurethane has a high durometer hardness) so that the polyurethane rubber composition has a durometer hardness of 75° to 95°, there is no need to use a filler to increase the durometer hardness of the polyurethane rubber composition. This is preferable because, unlike polyurethanes in which the durometer hardness is increased using a filler, there is no decrease in rubber elasticity or durability.

[0040] Examples of the curing agent component include an alcohol-based curing agent component, an amine-based curing agent component (C), and an aminoalcohol-based curing agent component. Examples of alcohol-based curing agent components include dihydric alcohols such as 1,4-butanediol, neopentyl glycol, and bishydroxyethoxybenzene, and trihydric or higher polyhydric alcohols such as trimethylolpropane and 1,2,6-hexanetriol. Examples of the amine curing agent component (C) include divalent amines such as trimethylhexamethylenediamine, p-phenylenediamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane (also known as methylenebisorthochloroaniline), 4,4'-diaminodiphenylmethane, dimethylthiotoluenediamine, and diethyltoluenediamine, and polyvalent amines such as triethylenetetramine and diethylenetriamine. Examples of the amino alcohol-based curing agent component include triethanolamine, triisopropanolamine, and diisopropanolamine. Among these, aromatic diamines such as 3,3'-dichloro-4,4'-diaminodiphenylmethane and 4,4'-diaminodiphenylmethane are preferred. When the amine-based curing agent component (C) is an aromatic diamine, the mechanical properties and rubber elasticity of the polyurethane rubber composition can be improved.

[0041] It is preferable that the mixing equivalent ratio in the prepolymer is such that the molar ratio r (NH2 / NCO) of the NCO group to the NH2 group contained in the curing agent component is about 0.9 (0.85 to 0.95). The ratio of the curing agent component to 100 parts by weight of the polymer component is preferably 5 to 15 parts by weight, and more preferably 8.5 to 12.5 parts by weight.

[0042] The polyurethane rubber composition preferably does not contain a filler, and in particular, it is preferable that the polyurethane rubber composition does not contain silica as a filler. One method for increasing the durometer hardness of a polyurethane rubber composition is to use a filler, but increasing the durometer hardness by using a filler may result in a decrease in rubber elasticity and durability. Therefore, it is preferable to increase the durometer hardness without using a filler. Other fillers that may not be included include carbon black, calcium carbonate, talc, clay, and titanium white.

[0043] The polyurethane rubber composition may contain additives such as a crosslinking agent, a hydrolysis stabilizer, a processing aid, a silane coupling agent, a plasticizer, an antioxidant, an antifoaming agent, and a flame retardant, in addition to the polymer component and the curing agent component.

[0044] Examples of polyurethane rubber compositions include cast urethane rubber, kneaded urethane rubber, and injection molding urethane rubber, with cast urethane rubber being preferred. Cast urethane rubber is made by heating and mixing a urethane prepolymer, which has been reacted in advance with an isocyanate and a polyol, with a curing agent component to obtain a liquid mixture, and then pouring this liquid mixture into a heated mold to form a mold. The molds and equipment used to manufacture cast urethane rubber are relatively inexpensive, complex shapes can be produced, the resulting molded products are easy to post-process, and the quality is stable.

[0045] It is preferably obtained by casting using a prepolymer of an ester-based polyurethane (A) and a prepolymer of an ether-based polyurethane (B) as polymer components constituting the polyurethane rubber composition. As the prepolymer of the ester-based polyurethane (A) and the prepolymer of the ether-based polyurethane (B), commercially available products can be used.

[0046] The following commercially available prepolymers of the ester polyurethane (A) can be used. A-9QM (Mitsui Chemicals, Inc.) Durometer hardness 93°, NCO content 4.20% L-1290 (Mitsui Chemicals, Inc.) Durometer hardness 91°, NCO content 4.13% L-1280 (Mitsui Chemicals, Inc.) Durometer hardness 81°, NCO content 3.37%

[0047] The following commercially available prepolymers of the ether-based polyurethane (B) can be used. L-1158 (Mitsui Chemicals, Inc.) Durometer hardness 91°, NCO content 4.39% L-1170 (Mitsui Chemicals, Inc.) Durometer hardness 71°, NCO content 2.47%

[0048] FIG. 2 is a flow diagram showing the manufacturing process of cast urethane rubber. First, the prepolymer of the ester-based polyurethane (A) and the prepolymer of the ether-based polyurethane (B) are preheated to soften them for easy mixing. Preheating can be performed, for example, at 100°C for 4 hours. Separately, the amine-based curing agent component (C) is heated (for example, to 120° C.) to dissolve it.

[0049] (mixture) The prepolymer of the ester-based polyurethane (A), the prepolymer of the ether-based polyurethane (B), and the amine-based curing agent component (C) are degassed under reduced pressure and mixed to obtain a mixture. (casting) A mold having a shape for forming the polyurethane rubber composition into the shape of the elastic layer is heated to a predetermined temperature (for example, 110° C.), and the mixture is poured (cast) into the mold. (hardening) The resin is first cured by holding it in the mold at a predetermined temperature for a predetermined time (for example, 110°C for 15 minutes). After the first curing, the resin is removed from the mold and held at a predetermined temperature for a further predetermined time (for example, 110°C for 12 hours) for the second curing. (Curing, post-processing) After secondary hardening, the product is left to cure at room temperature for about a week, and then post-processed (grinding, polishing, etc.) into the desired shape. By the above steps, a polyurethane rubber composition which is a cast urethane rubber can be obtained.

[0050] The polyurethane rubber composition can be shaped into a shape like the elastic layer 20 in FIG. 1 and pressed onto a shaft to obtain a paper feed roller. The thickness of the paper feed roller of the present invention is preferably 1 to 10 mm, and more preferably 3 to 7 mm.

[0051] The polyurethane rubber composition constituting the elastic layer of the paper-feeding roller of the present invention has excellent oil resistance. In particular, it has excellent oil resistance to both the petroleum-based oil PXE (phenylxylylethane) and higher fatty acid esters. The petroleum-based oil PXE and higher fatty acid esters are oils contained in microcapsules in carbonless paper, and are oils that adhere to the elastic layer of the paper feed roller when the carbonless paper is transported by the paper feed roller. Therefore, it is desirable that the elastic layer of the paper feed roller have good evaluation results for oil resistance using the petroleum-based oil PXE and higher fatty acid esters.

[0052] Examples of higher fatty acid esters include vegetable higher fatty acid esters, which are contained in vegetable oils, such as rice bran oil, corn oil, soybean oil, rapeseed oil, and palm oil. Examples of higher fatty acid esters used in the swelling resistance test include methyl oleate and methyl laurate.

[0053] The oil resistance of a rubber composition can be evaluated by the weight change rate when the rubber composition to be evaluated is immersed in a predetermined oil for a predetermined time. A test piece of the rubber composition (20 mm long x 20 mm wide x 2 mm high) is prepared and immersed in PXE or a higher fatty acid ester at 23°C for 2 days, and the weight change rate is measured.

[0054] The polyurethane rubber composition constituting the elastic layer of the paper-feeding roller of the present invention has high oil resistance to PXE and higher fatty acid esters (small weight change rate). For example, the weight change rate of the polyurethane rubber composition in the above test with respect to PXE is preferably 1.0% by weight or less, and more preferably 0.75% by weight or less. Furthermore, the weight change rate of the polyurethane rubber composition measured using methyl laurate as the higher fatty acid ester in the above test is preferably 1.0% by weight or less, more preferably 0.7% by weight or less, and even more preferably 0.5% by weight or less.

[0055] PXE and higher fatty acid esters differ in their polarity and solubility parameters (SP values). PXE has low polarity and a relatively small SP value of 7.5 to 7.8. Higher fatty acid esters have a slightly larger SP value of 8.5 to 8.8. If the SP value of the rubber composition and the SP value of the oil are close to each other, swelling of the oil in the polyurethane rubber composition is likely to occur.

[0056] The present inventors have investigated the relationship between the SP value of the rubber composition and the SP value of the oil and the swelling property, and have found that there are factors other than the SP value. Silicone rubber, a candidate material for use in the elastic layer of paper feed rollers, has an SP value of 7.3 to 7.6, which is close to the SP value of PXE, making it susceptible to swelling due to PXE. On the other hand, the SP value of silicone rubber is not close to that of higher fatty acid esters, so from the perspective of SP value, it is expected that swelling due to higher fatty acid esters would be unlikely to occur, but in reality swelling due to higher fatty acid esters does occur. The inventors investigated the cause of swelling of silicone rubber caused by higher fatty acid esters and hypothesized that the higher fatty acid esters penetrate into tiny intermolecular gaps in silicone rubber.

[0057] Based on this finding, the permeability of oil into polyurethane rubber compositions will be examined. The SP value of polyurethane rubber compositions is about 10.0, and the SP value of PXE is not close to this, so it is thought that PXE does not easily penetrate polyurethane rubber compositions. On the other hand, since the SP value of the polyurethane rubber composition is close to that of the higher fatty acid ester, it is considered that swelling caused by the higher fatty acid ester is likely to occur from the viewpoint of the SP value. Therefore, in order to prevent swelling due to the higher fatty acid ester, the durometer hardness of the polyurethane rubber composition is increased to 75° to 95°, reducing the gaps in the polyurethane rubber composition and preventing the penetration of the higher fatty acid ester into the gaps. In addition, increasing the hardness of the polyurethane rubber composition and narrowing the gaps between molecules further prevents the penetration of PXE. From the above viewpoints, by increasing the durometer hardness of the polyurethane rubber composition to 75° to 95°, it is possible to increase the oil resistance to both PXE and higher fatty acid esters.

[0058] The paper feed roller of the present invention is preferably a paper feed roller used in an electrophotographic apparatus or a dedicated scanner capable of transporting carbonless paper. In this specification, the phrase "an electrophotographic device or dedicated scanner capable of transporting carbonless paper" does not mean an electrophotographic device or dedicated scanner that transports only carbonless paper, but rather means an electrophotographic device or dedicated scanner that can transport ordinary printing paper, etc., and can also use carbonless paper as the object to be transported.

[0059] In this specification, the term "electrophotographic device" includes devices that have only the functions of a printer, copier, scanner, fax, etc., as well as multifunction devices that have multiple of these functions. In this specification, a special distinction is made between dedicated scanner devices that have only the scanner function. In some industries, such as banks and trading companies, there are dedicated scanner devices used to scan large volumes of carbonless paper.

[0060] The microcapsules in carbonless paper contain oil, so the oil seeps out of the microcapsules and comes into contact with the paper feed rollers that come into contact with the carbonless paper. Paper feed rollers used in dedicated scanners that scan large volumes of carbonless paper require particularly high oil resistance.

[0061] The paper feed roller of the present invention has excellent resistance to swelling caused by both aromatic petroleum oils and higher fatty acid esters, and is therefore particularly suitable for use as a paper feed roller in a dedicated scanner.

[0062] An electrophotographic apparatus or dedicated scanner device capable of transporting carbonless paper using the paper feed roller of the present invention is the electrophotographic apparatus or dedicated scanner device of the present invention. Furthermore, the microcapsules of the carbonless paper preferably contain aromatic petroleum oil and / or higher fatty acid ester. [Example]

[0063] Examples will be given below to explain the present invention more specifically, but the present invention is not limited to these examples.

[0064] (Examples 1 to 5) and (Comparative Examples 1 to 2) The following materials were prepared as the ester-based polyurethane (A), the ether-based polyurethane (B), and the amine-based curing agent component (C). Ester-based polyurethane (A): (A-1) A-9QM (manufactured by Mitsui Chemicals, Inc.) Durometer hardness 93°, NCO content 4.20% (A-2) L-1290 (Mitsui Chemicals, Inc.) Durometer hardness 91°, NCO content 4.13% (A-3) L-1280 (manufactured by Mitsui Chemicals, Inc.) Durometer hardness 81°, NCO content 3.37% Ether-based polyurethane (B): (B-1) L-1158 (manufactured by Mitsui Chemicals, Inc.) Durometer hardness 91°, NCO content 4.39% (B-2) L-1170 (manufactured by Mitsui Chemicals, Inc.) Durometer hardness 71°, NCO content 2.47% Amine-based hardener component (C): (C-1) 3,3'-dichloro-4,4'-diaminodiphenylmethane

[0065] The prepolymer of ester-based polyurethane (A) and the prepolymer of ether-based polyurethane (B) were softened at 100°C for 4 hours, and the amine-based curing agent component (C) was heated at 120°C to dissolve it. The prepolymer of the ester-based polyurethane (A), the prepolymer of the ether-based polyurethane (B), and the amine-based curing agent component (C) were degassed under reduced pressure and mixed to obtain a mixture. The mold was heated to a predetermined temperature (for example, 110°C), and the mixture was poured (cast) into the mold. The resin was first cured by holding it in the mold at 110°C for 15 minutes. After the first curing, it was removed from the mold and held at 110°C for a further 12 hours to perform the second curing. Through the above steps, a polyurethane rubber (polyurethane rubber composition) was obtained. Furthermore, the durometer hardness of each polyurethane rubber was measured. Table 1 shows the composition and hardness measurement results for each of the examples and comparative examples.

[0066] (Comparative Example 3) A commercially available ester-based polyurethane rubber (durometer hardness 70°) was prepared.

[0067] Comparative Example 4 A commercially available ether-based polyurethane rubber (durometer hardness 70°) was prepared.

[0068] (Comparative Example 5) A commercially available silicone rubber (durometer hardness 70°) was prepared.

[0069] (Oil resistance evaluation) Test pieces (length 20 mm x width 20 mm x height 2 mm) of polyurethane rubber and silicone rubber of each example and comparative example were prepared, and the test pieces were immersed in PXE or higher fatty acid ester at 23°C for 2 days, and the weight change rate was measured. The results of the weight change rate are shown in Table 1.

[0070] [Table 1]

[0071] The polyurethane rubbers of Examples 1 to 5 had durometer hardness of 75° to 95°, and the weight change rate for both PXE and methyl laurate was less than 1.0% by weight, demonstrating good oil resistance.

[0072] The polyurethane rubber of Comparative Example 1 did not contain the ether-based polyurethane (B) and had a high weight change rate relative to methyl laurate. Furthermore, although not shown as an evaluation index, it is presumed that the hydrolysis resistance was low because the polymer component consisted only of the ester-based polyurethane (A). The polyurethane rubber of Comparative Example 2 had a weight ratio (A) / (B) of 50 / 50, and the proportion of the ester-based polyurethane (A) with excellent oil resistance was low, so the weight change rate with respect to PXE and methyl laurate was high. The commercially available polyurethane rubbers of Comparative Examples 3 and 4 had a low hardness of 70° and a high weight change rate with respect to PXE and methyl laurate. The commercially available silicone rubber of Comparative Example 5 had a low hardness of 70° and a high weight change rate with respect to PXE and methyl laurate. [Explanation of symbols]

[0073] 1 Paper feed roller 10 Axial Body 20 Elastic layer

Claims

1. A paper feed roller comprising a shaft body and an elastic layer disposed around the shaft body, the elastic layer is made of a polyurethane rubber composition containing a polymer component and a curing agent component, the polymer component contains an ester-based polyurethane (A) and an ether-based polyurethane (B), and the weight ratio of the ester-based polyurethane (A) to the ether-based polyurethane (B) is (A) / (B)=90 / 10 to 60 / 40; the durometer hardness of the ester-based polyurethane (A) and the ether-based polyurethane (B) is both 65° to 95°; the curing agent component is an amine-based curing agent component (C), A paper feed roller characterized in that the elastic layer has a durometer hardness of 75° to 95°.

2. 2. The paper feed roller of claim 1, wherein the polyurethane rubber composition does not contain silica as a filler.

3. 2. The paper feed roller according to claim 1, wherein the polyurethane rubber composition is a cast urethane rubber.

4. 2. The paper feed roller according to claim 1, wherein the amine-based hardener component (C) is an aromatic diamine.

5. 5. An electrophotographic device or a dedicated scanner, capable of transporting carbonless paper using the paper feed roller according to claim 1.

6. 6. The electrophotographic apparatus or dedicated scanner according to claim 5, wherein the microcapsules of the carbonless paper contain aromatic petroleum oil and / or higher fatty acid ester.

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