JP2010132393A - Rubber member for paper feeding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber member for paper feeding, having a stable friction coefficient and an excellent heat resistance. <P>SOLUTION: The rubber member comprises a rubber-like elastic layer formed by vulcanizing and shaping a rubber composition containing a white carbon of 10-30 pts.mass as a filler to a rubber base material of 100 pts.mass which is based on hydrogenated acrylonitrile-butadiene rubber having an acrylonitrile content of 20 wt.% or more and a hydrogenation rate of 90% or more. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rubber member for paper feeding and conveyance used for paper feeding devices such as various printers such as inkjet printers and laser printers, various OA equipment such as copying machines, facsimiles (FAX), and the like, and in particular, high temperature of the paper feeding device. It is suitable for use in a site that tends to become.

  In a laser printer or a copier, a paper feeding / conveying roll is used to send printing paper to each mechanism. 2. Description of the Related Art Conventionally, a paper feeding / conveying roll is required to have a conveying force with a stable friction coefficient and to have excellent wear resistance. For these reasons, EPDM (ethylene / propylene / diene rubber) is used as a roll material having excellent mechanical strength and a high coefficient of friction.

  On the other hand, for high durability machines, urethane materials that are excellent in wear resistance have been studied as materials for paper feed and transport rolls (see Patent Document 1).

  Further, a paper feeding / conveying roll has been proposed in which the adhesion of paper dust due to static electricity is suppressed and the friction coefficient with time is small (see Patent Document 2).

  However, with the recent increase in the speed of OA equipment, there has been a problem that problems occur in the conventional paper feeding / conveying roll. This is considered to be because the toner-transferred paper heated in the fixing unit is sent out to the paper feeding / conveying roll before it is sufficiently cooled.

  The paper feeding / conveying roll is required to have excellent heat resistance and stable paper feeding / conveying performance.

JP 2005-206375 A Japanese Patent Laid-Open No. 10-45952

  In view of such circumstances, an object of the present invention is to provide a rubber member for paper feeding and conveyance having a stable coefficient of friction and excellent heat resistance.

  The first aspect of the present invention that solves the above problems is based on 100 parts by mass of a rubber base material mainly composed of hydrogenated acrylonitrile butadiene rubber having an acrylonitrile content of 20 wt% or more and a hydrogenation rate of 90% or more. A rubber member for paper feeding and conveyance, comprising a rubber-like elastic layer obtained by vulcanizing and molding a rubber composition containing 10 to 30 parts by mass of white carbon as a filler.

  According to a second aspect of the present invention, in the rubber member for paper feeding / conveying according to the first aspect, the rubber member for paper feeding / conveying has an absolute value of a frictional charging potential of 100 V or less. It is in the rubber member for paper conveyance.

  According to a third aspect of the present invention, in the rubber member for paper feeding / conveying according to the first or second aspect, the rubber member for paper feeding / conveying has a rubber hardness after standing at 130 ° C. for one month. A difference in rubber hardness is within 5 ° according to JIS A.

  According to a fourth aspect of the present invention, there is provided a rubber member for paper feeding / conveying, wherein the rubber member for paper feeding / conveying according to any one of the first to third aspects has a roll shape or a belt shape.

  According to the present invention, it is possible to provide a rubber member for sheet feeding and conveyance having a low charging potential due to friction and excellent heat resistance. By lowering the charging potential due to friction, adhesion of paper dust is suppressed, the friction coefficient is stabilized, and excellent heat resistance makes it suitable for use even at sites that tend to be hot.

  The rubber member for paper feeding / conveyance of the present invention is used as a filler for 100 parts by mass of a rubber base material mainly composed of hydrogenated acrylonitrile butadiene rubber having an acrylonitrile content of 20 wt% or more and a hydrogenation rate of 90% or more. It is composed of a rubber-like elastic layer obtained by vulcanizing and molding a rubber composition containing 10 to 30 parts by weight of white carbon, and realizes a rubber member for paper feeding and conveyance having a low charging potential due to friction and excellent heat resistance. Is. By using the predetermined hydrogenated acrylonitrile butadiene rubber, the charging potential due to friction can be lowered, the adhesion of paper dust can be suppressed, and the heat resistance can be made extremely excellent. In addition, by including a predetermined amount of filler, it is possible to have mechanical characteristics suitable for paper feed conveyance. Since the rubber member for paper feeding / conveying of the present invention is extremely excellent in heat resistance, the hardness and outer diameter do not change significantly even at high temperatures, and stable paper feeding / conveying property can be maintained. It can be used suitably for the part which becomes high temperature.

  The rubber base material is mainly composed of hydrogenated acrylonitrile butadiene rubber having an acrylonitrile content of 20 wt% or more and a hydrogenation rate of 90% or more. Hydrogenated acrylonitrile butadiene rubber (HNBR) is obtained by hydrogenating residual double bonds contained in butadiene in the polymer main chain of nitrile rubber (NBR). Such a hydrogenated acrylonitrile butadiene rubber has an acrylonitrile content (bound AN amount) of 20 wt% or more and a hydrogenation rate of 90% or more, and the acrylonitrile content is preferably 20 to 45 wt%. Thereby, while being excellent in mechanical strength, it can be made very excellent in heat resistance. Further, the charging potential due to friction can be low. In other words, it is possible to have conductivity sufficient to suppress static electricity generated during friction without using a conductivity imparting material such as an ionic conductive agent or carbon black. By reducing the charging potential due to friction, paper dust does not adhere even after long-term use, and the friction coefficient is hardly reduced. When the acrylonitrile content is less than 20 wt%, the heat resistance is lowered and sufficient wear resistance cannot be obtained. On the other hand, when the hydrogenation rate is less than 90%, the mechanical strength decreases, or the charging potential due to friction increases and the paper feeding / conveying performance decreases.

  The rubber base material only needs to be mainly composed of the above-mentioned hydrogenated acrylonitrile butadiene rubber, and other rubber materials may be appropriately blended. Examples of rubber base materials that can be blended include acrylonitrile butadiene rubber (NBR), epichlorohydrin rubber, polyurethane, chloroprene rubber (CR), and styrene rubber (SBR).

  A rubber composition contains 10-30 mass parts of white carbon as a filler with respect to 100 mass parts of rubber base materials. By blending a predetermined amount of white carbon into the rubber base material, it is possible to obtain a rubber member for paper feed / conveyance having a desired hardness, and there is no possibility of soiling the paper. That is, it can have a desired paper feeding / conveying performance without affecting the paper to be fed / conveyed. When the amount of white carbon added is less than 10 parts by mass, the hardness decreases and the desired mechanical properties cannot be obtained. When the amount exceeds 30 parts by mass, the hardness becomes too high and the transportability decreases. .

  As white carbon (silica-based filler), either dry silica or wet silica may be used, and is not particularly limited, but wet silica is preferable. Wet silica is excellent in dispersibility with respect to the rubber base material, and can further improve the wear resistance of the rubber member for feeding and conveying paper.

  The rubber composition may contain a silane coupling agent. The silane coupling agent preferably has an alkoxysilyl group and an alkyl group substituted with a functional group capable of reacting with a rubber substrate. By reacting the white carbon with the silanol group of the silane coupling agent, the silane coupling agent is fixed to the white carbon, and the functional group and the rubber base material react to form a strong skeleton structure. . Thereby, reinforcement is provided. Moreover, the dispersibility with respect to the rubber base material of white carbon improves by mix | blending a silane coupling agent. In addition, when using a silane coupling material, it is preferable to use wet silica as white carbon. This is because the silane coupling agent is excellent in reactivity with wet silica.

  Specific examples of the silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrisilane. Methoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, bis (3-triethoxysilylpropyl) polysulfide, bis (2-triethoxysilylethyl) polysulfide, Examples include bis (4-triethoxysilylbutyl) polysulfide, bis (3-trimethoxysilylpropyl) polysulfide, and bis (2-trimethoxysilylethyl) polysulfide. In particular, bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) disulfide, and the like can be given. Examples of commercially available products include Shin-Etsu Chemical KBM-846, Degussa Si-69, Si-75, and the like.

  Vulcanization of the rubber composition described above may be either peroxide vulcanization or sulfur vulcanization, but when the hydrogenation rate of the hydrogenated acrylonitrile butadiene rubber is 95% or more, peroxide vulcanization is performed. Is preferred.

  In the case of peroxide vulcanization, it is preferable to blend the peroxide vulcanizing agent in an amount of 3% by mass to 10% by mass with respect to the rubber base material. This is because when the amount of the peroxide vulcanizing agent is too small, the required mechanical strength cannot be obtained, and when the amount is too large, the durability becomes inferior. Examples of peroxide crosslinking agents include dibutyl peroxide, tert-butylcumyl peroxide, 2,5-dimethyl-2,5-dihexane, 2,5-dimethyl-2,5-dihexyne-3, 1,3-bis. (Tert-butylperoxyisopropyl) benzene, 1,1-bis (tertiarybutylperoxy) -3,3,5-trimethylcyclohexane, n-butyl-4,4-bis (tertiarybutylperoxy) valerate, And tertiary butyl peroxybenzoate, tertiary butyl peroxyisopropyl carbonate, and dicumyl peroxide. As commercially available products, Park Mill D-40 manufactured by Nippon Oil & Fats Co., Ltd., Kayaku Mill D40C manufactured by Kayaku Akzo Co., Ltd., DCP manufactured by Mitsui Chemicals Fine, and the like can be used.

  When the hydrogenation rate of the hydrogenated acrylonitrile butadiene rubber is 90 to 95%, sulfur vulcanization can be suitably performed. In the case of sulfur vulcanization, it is preferable to vulcanize using sulfur and a vulcanization accelerator. . Sulfur is preferably compounded in an amount of 0.3 to 5% by mass, particularly preferably 0.5 to 1.5% by mass, based on the rubber base material. It is because it can be made excellent in mechanical strength and durability by reducing the compounding amount of sulfur.

  You may mix | blend various additives, such as an anti-aging agent, antioxidant, a ultraviolet absorber, a pigment, and dye, with the rubber base material, filler, and vulcanizing agent which were mentioned above suitably. A rubber-like elastic layer can be obtained by vulcanizing and molding a rubber composition obtained by mixing these at a predetermined temperature.

  The rubber member for paper feed conveyance preferably has an absolute value of the frictional charging potential of 100 V or less. The frictional charging potential referred to here is the amount of static electricity that is charged on the surface of the paper feeding and conveying roll due to friction when used in contact with a mating member made of a rubber elastic body via printing paper. As for the absolute value of the triboelectric potential, the maximum value (representative value) when used for 120 seconds is preferably 100 V or less. When the absolute value of the frictional charging potential is 100 V or less, the adhesion of paper dust is suppressed and the decrease in the friction coefficient is suppressed. Thereby, it is possible to maintain the paper feeding / conveying performance for a long period of time.

  In addition, the rubber member for paper feeding / conveying preferably has a difference in rubber hardness after being left at 130 ° C. for one month within 5 ° according to JIS A. This is because the heat resistance is extremely excellent. The rubber member for feeding and conveying preferably has a hardness of 50 to 80 degrees according to JIS A.

  The rubber member for paper feed / conveyance of the present invention is composed of the rubber-like elastic layer described above, but may have other layers inside.

  The rubber member for paper feed conveyance according to the present invention is suitable for use in, for example, a paper feed roll, a transport roll, a paper feed conveyor belt, and the like.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to this.

Example 1
100 parts by mass of hydrogenated NBR (1) (acrylonitrile content 44 wt%, hydrogenation rate 91%), 20 parts by mass of white carbon (Ultrasil VN3: manufactured by Degussa Japan), 5 parts by mass of titanium oxide, 1 part by mass of stearic acid, 5 parts by mass of zinc oxide, 0.5 parts by mass of FEF carbon, 0.5 parts by mass of thiuram accelerator, 1 part by mass of sulfur, 0.5 parts by mass of thiazole accelerator were added and kneaded with rubber. The test piece of Example 1 was obtained by heating for minutes. In addition, a test piece is based on JISK6262.

(Example 2)
A test piece of Example 2 was obtained in the same manner as Example 1 except that white carbon was changed to 10 parts by mass.

(Example 3)
A test piece of Example 3 was obtained in the same manner as Example 1 except that white carbon was changed to 30 parts by mass.

Example 4
Test piece of Example 4 in the same manner as in Example 1 except that 100 parts by mass of hydrogenated NBR (2) (acrylonitrile content 25 wt%, hydrogenation rate 90%) was used instead of hydrogenated NBR (1) Got.

(Example 5)
In the same manner as in Example 1 except that 100 parts by mass of hydrogenated NBR (3) (acrylonitrile content 49.2 wt%, hydrogenation rate 90%) was used instead of hydrogenated NBR (1), A specimen was obtained.

(Example 6)
100 parts by mass of hydrogenated NBR (4) (acrylonitrile content 43 wt%, hydrogenation rate 99%), 20 parts by mass of white carbon, 5 parts by mass of titanium oxide, 1 part by mass of stearic acid, 5 parts by mass of zinc oxide, FEF carbon 0.5 parts by mass and 7 parts by mass of an organic peroxide crosslinking agent were added and kneaded with rubber, and a test piece of Example 6 was obtained in the same manner as Example 1.

(Example 7)
Test piece of Example 7 in the same manner as in Example 6, except that 100 parts by mass of hydrogenated NBR (5) (acrylonitrile content 20 wt%, hydrogenation rate 95%) was used instead of hydrogenated NBR (4) Got.

(Comparative Example 1)
Test piece of Comparative Example 1 in the same manner as in Example 5 except that 100 parts by mass of hydrogenated NBR (6) (acrylonitrile content 17 wt%, hydrogenation rate 96%) was used instead of hydrogenated NBR (3) Got.

(Comparative Example 2)
Test piece of Comparative Example 2 in the same manner as in Example 1 except that 100 parts by mass of hydrogenated NBR (7) (acrylonitrile content 17 wt%, hydrogenation rate 90%) was used instead of hydrogenated NBR (1) Got.

(Comparative Example 3)
Test piece of Comparative Example 3 in the same manner as in Example 1 except that 100 parts by mass of hydrogenated NBR (8) (acrylonitrile content 36 wt%, hydrogenation rate 83%) was used instead of hydrogenated NBR (1) Got.

(Comparative Example 4)
A test piece of Comparative Example 4 was obtained in the same manner as in Example 1 except that 100 parts by mass of EPDM was used instead of hydrogenated NBR (1).

(Comparative Example 5)
To 100 parts by mass of polycaprolactone diol (PCL), 38 parts by mass of 4,4′-diphenylmethane diisocyanate (MDI) and 7.3 parts by mass of a chain extender are added and heated at 100 ° C. for 3 hours to cause a curing reaction. A test piece of Comparative Example 5 was obtained. In addition, a test piece is based on JISK6262.

(Comparative Example 6)
A test piece of Comparative Example 6 was obtained in the same manner as in Example 1 except that the white carbon was changed to 5 parts by mass.

(Comparative Example 7)
A test piece of Comparative Example 7 was obtained in the same manner as in Example 1 except that the white carbon was changed to 40 parts by mass.

(Test Example 1)
About the test piece of each Example and each comparative example, the rubber hardness (JIS A) in 25 degreeC was measured based on JISK6301. The results are shown in Tables 1 and 2.

(Test Example 2) Heat resistance test The test pieces of each Example and each Comparative Example were left in an oven maintained at 130 ° C, and rubber hardness (JIS A) was measured according to JIS K6301. The change over time in rubber hardness is shown in FIGS.

  Further, when the difference between the rubber hardness after standing for one month and the rubber hardness measured in Test Example 1 was within ± 5 °, it was judged as “good”, and when it was larger than ± 5 °, it was judged as “poor”. In addition, even if the difference from the rubber hardness measured in Test Example 1 was within ± 5 °, it was determined as x when the surface was deteriorated. The results are shown in Tables 1 and 2.

(Test Example 3) Humidity and heat test The test pieces of each Example and each Comparative Example were allowed to stand in a constant temperature and humidity layer of saturated steam at 60 ° C, and rubber hardness (JIS A) was measured according to JIS K6301. Changes in rubber hardness over time are shown in FIGS.

  Further, when the difference between the rubber hardness after standing for one month and the rubber hardness measured in Test Example 1 was within ± 5 °, it was judged as “good”, and when it was larger than ± 5 °, it was judged as “poor”. In addition, even if the difference from the rubber hardness measured in Test Example 1 was within ± 5 °, it was determined as x when the surface was deteriorated. The results are shown in Tables 1 and 2.

(Test Example 4) Friction charging test In each of the examples and the comparative examples, a paper feed transport roll having an outer diameter of 24 mm, an inner diameter of 15 mm, and a length of 24 mm was manufactured. A free roll was arranged so as to face the manufactured paper feeding / conveying roll. A test paper (type 6200 [64 g / m ² ]; manufactured by Ricoh Co., Ltd.) is placed between the paper feed transport roll and the free roll made of rubber elastic material, and is fed in an indoor environment at 23 ° C. and 55%. The transport roll was rotated at a rotation speed of 50 rpm. At this time, the amount of static electricity (friction charging potential) generated on the surface of the paper feeding / conveying roll was measured with a high precision static electricity sensor (SK-200; manufactured by Keyence Corporation). The measurement time was 120 seconds. As a criterion, ○ when the representative value of the triboelectric potential for 120 seconds is 100 V or less, Δ when it is 101 V to 1 kV, and × when it is larger than 1 kV and when the measured value is unstable. Judged. The results are shown in Tables 1 and 2 and FIGS.

(Test Example 5) Friction coefficient measurement In each example and each comparative example, a paper feed transport roll having an outer diameter of 24 mm, an inner diameter of 15 mm, and a length of 24 mm was manufactured. The manufactured paper feeding / conveying roll was fixed with a clutch, and a free roll was disposed so as to face the roll. A test paper (type 6200 [64 g / m ² ]; manufactured by Ricoh Co., Ltd.) is placed between the paper feed transport roll and the free roll, and a load cell that moves one end of the test paper at a constant speed (50 mm / second). After mounting, the static friction coefficient (initial static friction coefficient) acting between the paper feed transport roll and the test paper was measured.

  Similarly, the static friction coefficient (static friction coefficient after electric potential measurement) of each of the examples and comparative examples after the test of Test Example 4 was measured. The rate of change of the coefficient of friction after the potential measurement when the initial static friction coefficient was used as a reference was obtained, and the case where the rate of change was less than 10.0% was judged as ◯, and the case where it was 10.0% or more was judged as x. . The results are shown in Table 1, Table 2 and FIG.

(Summary of results)
The test pieces of Examples 1 to 7 all had small changes in rubber hardness even at high temperatures and high humidity, and were excellent in heat resistance and wet heat properties.

  On the other hand, the test piece of Comparative Example 1 using hydrogenated NBR having an acrylonitrile content of 17 wt% was found to have deteriorated due to the fact that the change in hardness in a high temperature environment was small, but the adhesiveness was confirmed on the surface. . Further, the test piece of Comparative Example 2 using hydrogenated NBR having an acrylonitrile content of 17 wt% and the test piece of Comparative Example 3 using hydrogenated NBR having a hydrogenation rate of 83% have a large hardness change at high temperatures, It was found that the heat resistance was low. Moreover, the test piece of Comparative Example 2 had a large hardness change and low wet heat property even in the wet heat test. The test piece of Comparative Example 5 made of polyurethane was low in heat resistance and wet heat resistance. The test piece of Comparative Example 6 with a small amount of white carbon added had a large change in hardness at high temperatures and low heat resistance.

  The test pieces of Examples 1 to 7 had a triboelectric charge potential of 100 V or less after 125 seconds in the triboelectric test. From this, it was found that the test pieces of Examples 1 to 7 have a low electrification potential due to friction and are excellent in charging characteristics, so that adhesion of paper powder is prevented during use.

  On the other hand, the test pieces of Comparative Example 1 and Comparative Example 2 using hydrogenated NBR having a low acrylonitrile content had a higher frictional charging potential than the test pieces of Examples 1-7. Further, the test piece of Comparative Example 4 using EPDM had a very high triboelectric potential, and the electric charge was likely to accumulate, and the paper powder was liable to adhere.

  In addition, the test piece of Comparative Example 7 had a representative value of −750 V for the frictional charging potential for 120 seconds. Furthermore, the triboelectric charging potential varied greatly between -230 V to -750 V between 60 seconds and 120 seconds, and was very unstable. Furthermore, when the triboelectric charge potential was measured in a low temperature and low humidity environment of 10 ° C. and 15%, the test piece of Comparative Example 7 generated a triboelectric charge potential exceeding 1 kV. As a result, it was found that when the temperature is low and the humidity is low, the electric charge is likely to accumulate and the paper dust is likely to adhere.

  Moreover, it turned out that the test piece of Examples 1-7 has a small rate of change of a friction coefficient, and can obtain a predetermined | prescribed friction coefficient stably.

  On the other hand, the test piece of Comparative Example 1 exhibited strong adhesiveness, and a large amount of paper powder adhered, so the friction coefficient was greatly reduced. Further, in the test pieces of Comparative Example 4 and Comparative Example 6, paper dust adhered to the roll surface due to the action of static electricity charged on the roll surface, and the friction coefficient was lowered.

  From the above, it was found that the rubber member for paper feeding / conveyance of the present invention is excellent in heat resistance and moist heat property, and can be suitably used even in a high temperature environment or a humid environment. It was also found that the frictional charging potential was kept low, and the friction coefficient was stable even after long-term use.

5 is a graph showing a change with time in rubber hardness of an example in Test Example 2. 5 is a graph showing a change with time in rubber hardness of a comparative example in Test Example 2. 6 is a graph showing a change with time in rubber hardness of an example in Test Example 3. 6 is a graph showing a change with time in rubber hardness of a comparative example in Test Example 3. 6 is a graph showing a change with time of a frictional charging potential of an example in Test Example 4. 6 is a graph showing a change with time of a frictional charging potential of a comparative example in Test Example 4. The graph which shows the time-dependent change of the triboelectric charge potential of the Example in the test example 4 is expanded. The graph which shows the time-dependent change of the triboelectric charge potential of the comparative example in Test Example 4 is enlarged. 10 is a graph showing the results of Test Example 5.

Claims (4)

A rubber composition containing 10 to 30 parts by weight of white carbon as a filler with respect to 100 parts by weight of a rubber base material mainly composed of hydrogenated acrylonitrile butadiene rubber having an acrylonitrile content of 20 wt% or more and a hydrogenation rate of 90% or more. A rubber member for paper feeding and conveyance comprising a rubber-like elastic layer obtained by vulcanizing and molding an object. 2. The rubber member for paper feeding / conveying according to claim 1, wherein the absolute value of the frictional charging potential is 100 V or less. 3. The rubber member for paper feed / conveyance according to claim 1 or 2, wherein the rubber member for paper feed / conveyance has a difference in rubber hardness after leaving for 1 month at 130 ° C. to 5 ° in JIS A. A rubber member for paper feed conveyance, wherein The rubber member for paper feed conveyance according to any one of claims 1 to 3, wherein the rubber member for paper feed conveyance is a roll shape or a belt shape.