Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L7/00—Compositions of natural rubber
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L11/00—Compositions of homopolymers or copolymers of chloroprene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons

Definitions

• the present invention relates to a rubber composition used for an air spring for a railway vehicle, particularly a diaphragm portion thereof, and has excellent cold resistance and ozone resistance that can withstand use in a cold region, and rubber / rubber bonding. It is related with the rubber composition excellent in the adhesiveness and adhesiveness in a part.
• An air spring for a railway vehicle has a structure as shown in FIGS. 1 to 4 of Patent Document 1, for example, and seals between a rubber inner cylinder (lower surface plate), outer cylinder (upper surface plate), and inner and outer cylinders. And a laminated rubber (stopper rubber) provided in order to reduce deterioration of the riding comfort of the vehicle during deflation.
• the diaphragm portion is formed by bonding a plurality of rubber sheets and reinforcing cords (rubber sheets reinforced with fiber cords), and seals compressed air. And in an air spring, this diaphragm part mainly exhibits a buffer function, and reduces the vibration added to a vehicle.
• the air spring is desired to have excellent cold resistance that can be used in a cold region, for example, the property that the rubber elasticity is hardly lowered and cracks are not generated even at low temperatures.
• Patent Document 2 discloses 100 parts by weight of styrene butadiene rubber (SBR) as a cold-resistant mold rubber (packing, gasket, seal, etc.) having sufficient mechanical strength even at low temperatures, and an iodine adsorption amount of 80 to 130 mg.
• SBR styrene butadiene rubber
• a cold-resistant rubber which uses 30 to 50 parts by weight of carbon black / g, 10 to 30 parts by weight of naphthenic process oil, 1 to 2 parts by weight of sulfur, and a vulcanization accelerator (claim 1).
• a slow-acting accelerator such as a sulfenamide accelerator as a vulcanization accelerator It is stated that cold resistance can be improved without lowering the mechanical strength by using a material that contains. Furthermore, it is stated that natural rubber (NR), butadiene rubber (BR), chloroprene rubber (CR) and the like may be blended.
• Patent Document 3 further contains a predetermined amount of ethylene / ⁇ -olefin / diene copolymer rubber (EPDM) in a rubber composition for an air spring containing a rubber component mainly composed of NR and BR.
• EPDM ethylene / ⁇ -olefin / diene copolymer rubber
• Patent Document 4 contains a predetermined amount of polychloroprene rubber (CR) in addition to a rubber composition for an air spring containing a rubber component mainly composed of NR and BR.
• a rubber composition is disclosed.
• the rubbers (compositions) disclosed in Patent Documents 2 to 4 have insufficient ozone resistance according to a dynamic ozone deterioration test (JIS K6259), and further improvement in ozone resistance has been desired.
• the dynamic ozone degradation test evaluates the state of cracking of rubber when a test piece is exposed to air containing ozone at a constant concentration while repeatedly applying strain. This is an evaluation in a near environment (the ozone resistance test in Patent Documents 3 and 4 is considered to be a static ozone deterioration test that does not necessarily correspond to actual use conditions). Therefore, hereinafter, “ozone resistance” refers to this dynamic ozone resistance.
• the term “cold resistance” simply refers to the property that the rubber elasticity is small and cracks do not occur even at low temperatures, specifically, the embrittlement temperature is low as measured by JIS K6261.
• the diaphragm portion of the air spring is formed by bonding a plurality of rubber sheets and reinforcing cords, and then vulcanizing. Therefore, a strong adhesive force (rubber / rubber adhesive force) between the rubber sheets after vulcanization is desired so that peeling between the rubber sheets does not occur when using an air spring. In particular, it is considered that stress concentrates on the rubber / rubber bonding portion of the diaphragm at a low temperature, and peeling is likely to occur. Therefore, reinforcement of the rubber / rubber adhesion is desired.
• the present invention relates to a rubber composition that can be suitably used for a vehicle air spring used in a cold region, and is excellent in both ozone resistance and cold resistance (expressed by a dynamic ozone deterioration test), and further rubber. It is an object to provide a rubber composition having excellent rubber adhesion and tackiness.
• a first aspect of the present invention contains butadiene rubber (BR), chloroprene rubber (CR) and natural rubber (NR), and BR is 10 to 35 masses with respect to a total of 100 mass parts of the BR, CR and NR. Part, CR of 50 to 75 parts by mass, and NR of 10 to 35 parts by mass.
• BR butadiene rubber
• CR chloroprene rubber
• NR natural rubber
• a part of the NR is at least one selected from the group consisting of styrene butadiene rubber (SBR) and nitrile rubber (acrylonitrile butadiene rubber: NBR).
• SBR styrene butadiene rubber
• NBR nitrile rubber
• the BR content is 10 to 35 parts by mass
• the CR content is 50 to 75 parts by mass
• the NR and the BR, CR, NR and the specific rubber are 100 parts by mass in total.
• the cold-resistant rubber composition has a total content of the specific rubber of 10 to 35 parts by mass, and the content of the specific rubber is preferably 10 to 60% by mass with respect to the total content of NR and the specific rubber. .
• both the ozone resistance and the cold resistance are excellent, and further, the rubber / rubber adhesiveness and the rubber / rubber adhesive force at the time of manufacturing the air spring are excellent, and it is used in a cold region.
• a rubber composition that can be suitably used for the manufacture of a vehicle air spring is provided.
• a rubber composition which is excellent in both ozone resistance, cold resistance and adhesiveness and further excellent in rubber / rubber adhesion (as compared with the first aspect). Therefore, when this rubber composition is applied to the formation of an air spring, ozone / cold resistance and excellent adhesiveness between rubber / rubber, as well as stronger rubber / Since rubber adhesive force can be given, it can be suitably applied to the manufacture of a vehicle air spring used in cold regions.
• the inventor is a rubber composition in which BR, CR, and NR are mixed, and the main component is CR, and the mixing ratio thereof is within a predetermined range, so that ozone resistance and cold resistance can be improved. It was found that a rubber excellent in both, rubber / rubber adhesive strength and rubber / rubber adhesion was obtained, and the present invention of the first aspect was completed.
• the present inventor further has excellent ozone resistance and cold resistance by replacing a part of NR with SBR or NBR in a rubber composition in which the above-mentioned BR, CR and NR are mixed at a mixing ratio within a predetermined range.
• the rubber / rubber adhesive strength was further improved while maintaining the rubber properties and the rubber / rubber adhesiveness, and the second aspect of the present invention was completed.
• the first aspect of the present invention contains BR, CR and NR, and BR is 10 to 35 masses with respect to 100 parts by mass in total of the BR, CR and NR. Part, CR of 50 to 75 parts by mass and NR of 10 to 35 parts by mass.
• the rubber composition according to the first aspect of the present invention is characterized in that BR, CR, and NR are mixed at a composition ratio in the above range. Due to this feature, excellent ozone resistance and cold resistance can be obtained. Moreover, it is excellent in adhesiveness. Therefore, since it can be temporarily fixed with sufficient adhesive force when the rubber is bonded, it is excellent in moldability in the production of an air spring. *
• BR is a synthetic rubber obtained by polymerization of butadiene.
• BR includes a high cis type having a large ratio of cis-1,4 bonds, a low cis type having a relatively small ratio of cis-1,4 bonds, and a high cis type-syndiotactic polybutadiene complex. It can be preferably used.
• high cis BR having a very low glass transition temperature (Tg) of ⁇ 95 to ⁇ 110 ° C. is preferable.
• Examples of the high cis type BR include JSR BR01 (manufactured by JSR), Nipole BR1220 (manufactured by Nippon Zeon), Ubepol BR150 (manufactured by Ube Industries), and the like.
• As the high cis-syndiotactic polybutadiene composite such as diene NF35R (manufactured by Asahi Kasei Co., Ltd.), those sold under the trade name such as Ubepol VCR412 (manufactured by Ube Industries) can be used.
• NR is a rubber made of rubber tree sap (latex) and mainly composed of cis-polyisoprene.
• RSS # 1, RSS # 3, etc. can be used, and what kneaded and adjusted the viscosity suitably is used.
• CR is a synthetic rubber obtained by polymerization of chloroprene and sold under a trade name such as Neoprene (registered trademark).
• Neoprene registered trademark
• the CR compounding ratio is in the range of 50 to 75 parts by mass with respect to 100 parts by mass in total of BR, CR and NR.
• the blending ratio of CR is less than 50 parts by mass, dynamic ozone resistance is lowered and it becomes difficult to obtain excellent ozone resistance.
• the blending ratio exceeds 75 parts by mass, a sufficient amount of BR or NR cannot be blended, and the cold resistance is lowered (the embrittlement temperature is increased), so that it can be used even in extremely cold regions where the temperature is ⁇ 40 to ⁇ 50 ° C. It becomes difficult to obtain an embrittlement temperature ( ⁇ 60 ° C. or less).
• the blending ratio of BR is in the range of 10 to 35 parts by mass with respect to 100 parts by mass of BR, CR and NR in total.
• the blending ratio of BR is less than 10 parts by mass (even when the blending ratio of CR is in the range of 50 to 75 parts by mass)
• the cold resistance is lowered (the embrittlement temperature is increased) and brittleness of ⁇ 60 ° C. or less It becomes difficult to obtain the crystallization temperature.
• the rubber / rubber adhesion is reduced.
• the blending ratio exceeds 35 parts by mass, it is necessary to reduce the blending ratio of NR and the adhesiveness is lowered.
• the blending ratio of NR is in the range of 10 to 35 parts by mass with respect to 100 parts by mass of BR, CR and NR in total.
• the blending ratio of NR is less than 10 parts by mass, the tackiness is lowered.
• the compounding ratio exceeds 35 parts by mass (when the CR compounding ratio is in the range of 50 to 75 parts by mass, it is necessary to reduce the BR compounding ratio), cold resistance decreases (the embrittlement temperature increases). ) And an embrittlement temperature of ⁇ 60 ° C. or less becomes difficult to obtain.
• the 2nd aspect of this invention is the 1st aspect of this invention. At least 1 specific rubber chosen from the group which consists of SBR and NBR in said 1st aspect of said NR.
• the cold resistant rubber composition replaced with
• the BR content is 10 to 35 parts by mass
• the CR content is 50 to 75 parts by mass
• the NR and the BR, CR, NR and the specific rubber are 100 parts by mass in total.
• the cold-resistant rubber composition has a total content of the specific rubber of 10 to 35 parts by mass, and the content of the specific rubber is preferably 10 to 60% by mass with respect to the total content of NR and the specific rubber. .
• the diaphragm portion of the air spring is formed by laminating a plurality of rubber sheets and reinforcing cords, so that a strong adhesive force between the rubber sheets (rubber / Rubber adhesion) is desired.
• rubber / Rubber adhesion Rubber adhesion
• the present inventor replaces a part of NR in the rubber composition of the first aspect, that is, the rubber compound excellent in cold resistance and ozone resistance with SBR or NBR, thereby obtaining “cold resistance”, “resistance to resistance”.
• the inventors have found that “rubber / rubber adhesion” can be further improved while maintaining “ozone property” and “tackiness”, and have completed the invention of the second aspect.
• SBR is a copolymer of styrene and butadiene.
• SBR includes emulsion polymerization SBR (E-SBR) and solution polymerization SBR (S-SBR), both of which can be suitably used, but have a low glass transition temperature (Tg) and a low amount of bound styrene. Those are more preferred.
• E-SBR emulsion polymerization SBR
• S-SBR solution polymerization SBR
• Tg glass transition temperature
• JSR 1500 made by JSR
• NBR is a copolymer of acrylonitrile and butadiene, and can be suitably used regardless of the brand, but more preferably has a low glass transition temperature (Tg) and a low amount of bound acrylonitrile.
• Tg glass transition temperature
• NBR what is marketed by brand names, such as Nipol 1043 (made by Nippon Zeon), Nipole DN401LL (made by Nippon Zeon), JSR ⁇ ⁇ N250SL (made by JSR), can be used, for example.
• Rubber / rubber adhesion can be improved by replacing a part of NR constituting the rubber composition of the first aspect with SBR or NBR.
• SBR and NBR are slightly inferior in tack to NR, but if the ratio of replacing NR with SBR or NBR is within a predetermined range, the rubber / rubber adhesion can be improved while maintaining the tack. .
• the compounding ratio of CR is in the range of 50 to 75 parts by mass with respect to 100 parts by mass in total of BR, CR, NR and specific rubber.
• the blending ratio of CR is less than 50 parts by mass, dynamic ozone resistance is lowered and it becomes difficult to obtain excellent ozone resistance.
• the blending ratio exceeds 75 parts by mass, a sufficient amount of BR, NR or the like cannot be blended, the cold resistance is lowered (the embrittlement temperature is increased), and the embrittlement temperature of ⁇ 60 ° C. or less is hardly obtained.
• the blending ratio of BR is in the range of 10 to 35 parts by weight, preferably 15 to 30 parts by weight with respect to 100 parts by weight of BR, CR, NR and the specific rubber in total. It is a range.
• the blending ratio of BR is less than 10 parts by mass (even when the blending ratio of CR is in the range of 50 to 75 parts by mass), the cold resistance is lowered (the embrittlement temperature is increased), and brittleness of ⁇ 60 ° C. or less is achieved. It becomes difficult to obtain the crystallization temperature.
• the compounding ratio exceeds 35 parts by mass, it is necessary to reduce the total compounding ratio of NR and specific rubber, and the adhesiveness is lowered.
• the total compounding ratio of NR and specific rubber is in the range of 10 to 35 parts by mass, preferably 15 to 100 parts by mass in total of BR, CR, NR and specific rubber.
• the range is from 30 parts by mass.
• the total compounding ratio of NR and specific rubber is less than 10 parts by mass, the tackiness is lowered.
• the total compounding ratio exceeds 35 parts by mass (when the CR compounding ratio is in the range of 50 to 75 parts by mass, it is necessary to reduce the BR compounding ratio), cold resistance decreases (embrittlement temperature). ) And an embrittlement temperature of ⁇ 60 ° C. or less becomes difficult to obtain.
• the content of the specific rubber is 10 to 60% by mass with respect to the total content of NR and the specific rubber. Is preferred. By replacing 10 to 60% by mass of NR with a specific rubber, the “rubber / rubber adhesion” can be further increased.
• the content of the specific rubber is less than 10% by mass relative to the total content of NR and the specific rubber, the effect of improving the “rubber / rubber adhesion” is small, and the content of the specific rubber exceeds 60% by mass In some cases, the tackiness of the rubber becomes insufficient.
• additives, etc. for any of the rubber compositions of the first aspect and the second aspect, in addition to the above essential composition, the additives, etc., as long as they do not impair the spirit of the invention.
• Other ingredients can be blended.
• Other components include reinforcing fillers such as carbon and silica, vulcanizing agents, vulcanization accelerators, vulcanization acceleration aids, vulcanization retarders, anti-aging agents, plasticizers, silane coupling agents, and the like. be able to.
• an ester compound (DOP, DOA, etc.) excellent in low-temperature fluidity is used as a plasticizer, the embrittlement temperature can be further lowered, but the plasticizer bleeds continuously or extracted with water or a cleaning solution. As a result, it can be considered that the effect of improving cold resistance is reduced over time. Therefore, it is desirable to select a rubber that exhibits sufficient cold resistance without using these plasticizers.
• the cold-resistant rubber composition of the first aspect has a low embrittlement temperature and excellent cold resistance, and also has ozone resistance, ie, dynamic resistance. Excellent ozone and rubber / rubber adhesion. Furthermore, since it is excellent in adhesiveness, it can be temporarily fixed with sufficient adhesive force at the time of bonding, and the moldability at the time of manufacturing an air spring is good. Therefore, it is suitable as a constituent material of an air spring of a railway vehicle used in a cold region.
• the cold resistant rubber of the second aspect is excellent in cold resistance, ozone resistance and adhesiveness, and “rubber / rubber adhesion” is more excellent than the first aspect, so it is used in cold regions. It is further suitable as a constituent material of an air spring of a railway vehicle.
• an air spring for a railway vehicle formed using the rubber composition of the first embodiment or the rubber composition of the second embodiment.
• Adhesiveness After pasting the unvulcanized rubber sheet, the peel strength was measured by a 180 ° peel test (peel speed: 50 mm / min), and ⁇ 0.20 kgf / 25 mm passed, ⁇ 0.40 kgf / 25 mm It evaluated as a more preferable measured value.
• -Adhesiveness After vulcanizing and pressing an unvulcanized rubber sheet, the adhesive strength of rubber / rubber is measured by a 180 ° peel test (peel speed: 50 mm / min), and ⁇ 10 kgf / 25 mm is passed, ⁇ 15 kgf / 25 mm was evaluated as a more preferable measurement value.
• the range of mass% and the blending ratio of NR should be in the range of 10 to 35 mass%. Note that with J having a BR blending ratio of 10% by mass, the embrittlement temperature ⁇ ⁇ 60 ° C., which is the preferred cold resistance, is not obtained. Further, when the blending ratio of NR is 10% by mass, a preferable adhesiveness of ⁇ 0.40 kgf / 25 mm is not obtained. This result suggests that the blending ratio of BR is preferably 15 to 30% by weight, the blending ratio of NR is preferably 15 to 30% by weight, and therefore the blending ratio of CR is preferably 50 to 70% by weight.
• O, P, Q and R described in Table 4 are the same as G, which is a specific example of the first embodiment, in the composition ratio of CR and BR, but a part of NR in G (25 %, 50% or 75%) or all of them are replaced with SBR.
• S, T, U and V described in Table 5 are the same as G, which is one specific example of the first embodiment, in the composition ratio of CR and BR, but a part of NR in G (25 %, 50% or 75%) or all of them are replaced with NBR.
• the adhesive column of Tables 4 and 5 Q in which 75% of NR of G was replaced with SBR and R in which all of G was replaced, and 75% of NR in G was replaced with NBR.
• the adhesiveness is lowered, and preferable adhesiveness (0.4 kgf / 25 mm or more) is not obtained. Therefore, in order to obtain preferable tackiness, it is suggested that the ratio of NR substitution by SBR or NBR is preferably 60% by mass or less of NR.
• the rubber composition of group 1 in which only 20% by mass of SBR is blended with CR without blending NR and BR, and the rubber composition of group 2 in which only 20% by mass of NBR is blended have low cold resistance and become brittle.
• the temperature is higher than -50 ° C.
• U where 75% of NR is replaced with NBR and V where all are replaced cold resistance tends to decrease (although the standard is satisfied).
• the inventions of the first aspect and the second aspect are suitably used for air springs for railway vehicles used in cold districts, such as air springs for vehicles.

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• 2013
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