JP6503640B2 - Rubber composition for anti-vibration rubber for automobile and anti-vibration rubber for automobile - Google Patents

Description

  The present invention relates to a vibration-proof rubber composition which can be suitably used under high temperature and low temperature environments, and a vibration-proof rubber obtained by curing the composition.

  As the basic characteristics of the anti-vibration rubber, strength characteristics to support heavy objects such as an engine and the like, and anti-vibration performance to absorb and suppress the vibration thereof are required. Furthermore, when used under a high temperature environment such as an engine room, it is required to be excellent in heat resistance aging as well as being excellent in strength characteristics, low in dynamic magnification and excellent in anti-vibration performance. Moreover, in addition to the above, since a car is used also in a high latitude area, a low temperature characteristic is also required for the anti-vibration rubber for a car.

  As described above, in order to impart comprehensively superior characteristics, developments have been actively conducted to blend predetermined amounts of rubber components of a vibration-proof rubber, a crosslinking system and other additives, and many patent applications have been made. Even though they are excellent in heat aging resistance and dynamic magnification, they are often inferior in terms of low temperature characteristics and the like.

  In addition, the present applicant previously added heat resistance aging and dynamic resistance as compared to the prior art by adding N-phenyl-N- (trichloromethylthio) benzenesulfonamide to the compounding component of the crosslinking system at a constant ratio. The vibration-proof rubber composition excellent in magnification is proposed (Unexamined-Japanese-Patent No. 2012-229323). However, even with the above proposal, there is room for further improvement in the low temperature characteristics of the anti-vibration rubber.

JP, 2012-229323, A

  The present invention has been made in view of the above circumstances, and is a vibration-proof rubber composition capable of further improving low temperature characteristics while maintaining basic characteristics of strength characteristics (hardness, tensile elongation, tensile strength), and An object of the present invention is to provide a vibration-proof rubber obtained by curing the rubber composition.

  As a result of intensive studies to achieve the above object, the present inventor has formulated a mixture of a natural rubber and a high trans content isoprene rubber, and determined the blending ratio of the high trans content isoprene rubber in this mixture. By adding the rubber component adjusted in the range and each compounding component of the crosslinking agent and the aromatic sulfonamides, the combined effect of these components can significantly improve the low temperature characteristics, and the strength characteristics (hardness, tensile elongation, etc.) It has been discovered that it is possible to maintain good tensile strength, and the present invention has been achieved.

Therefore, the present invention provides the following rubber composition for vibration proof rubber for automobiles and the vibration proof rubber for vehicles .
1. Natural rubber, high trans content isoprene rubber having a trans-1,4 bond content of 95% or more, sulfur and an aromatic sulfonamide having a specific structural formula Composition.
2. The rubber for automotive vibration-proof rubbers according to 1 above, wherein the blending ratio of the high trans content isoprene rubber is less than 20% by mass with respect to the rubber component of the above natural rubber (NR) and the high trans content isoprene rubber (IR) Composition.
3. The compounded amount of the above- mentioned aromatic sulfonamides is 0.1 to 4 parts by mass with respect to 100 parts by mass of a rubber component containing the above-mentioned natural rubber (NR) and high trans content isoprene rubber (IR) Rubber composition for anti-vibration rubber for automobiles.
4. The above aromatic sulfonamides are N-phenyl-N- (monochloromethylthio) toluenesulfonamide, N-phenyl-N- (dichloromethylthio) toluenesulfonamide, N-phenyl-N- (trichloromethylthio) benzenesulfonamide, Compounds selected from the group of N-phenyl-N- (dichloromethylthio) benzenesulfonamide, N-phenyl-N- (trichloroethylthio) benzenesulfonamide, and N-phenyl-N- (trichloropropylthio) benzenesulfonamide The rubber composition for vibration-proof rubbers for motor vehicles as described in any one of said 1 to 3 which is it.
5. The vibration-proof rubber for motor vehicles which hardens the rubber composition in any one of said 1-4.

  The vibration-proof rubber composition of the present invention can significantly improve low temperature properties while maintaining the basic properties of tensile properties (elongation, strength).

  The rubber component of the vibration-proof rubber composition of the present invention is a combination of natural rubber (NR) and high trans content isoprene rubber (IR) as main components. At that time, the blending ratio of the high trans content isoprene rubber is adjusted to be less than 20% by mass with respect to the rubber components of the natural rubber (NR) and the high trans content isoprene rubber (IR). It is particularly preferable that the blending ratio of natural rubber (NR) to high trans content isoprene rubber (IR) is in the range of 99 to 81: 1 to 19 in mass ratio. Natural rubber (NR) has a cis-1,4 bond content of 100% except for some trans bonds at the molecular chain end, and the proportion of the above high trans content isoprene rubber (IR) is less than the above range In addition, the trans ratio in the rubber component may be too low compared to the cis ratio, and the improvement in low temperature characteristics may be reduced. If it is too high, the proper cis / trans ratio in the rubber component can not be maintained, so low temperature There is a possibility that the degree of improvement of the characteristics is reduced.

  The NR described above is not particularly limited and may be selected appropriately from known ones, and examples thereof include RSS (Ribbed smoked sheets), TSR (Technically Specified Rubber), and the like.

  On the other hand, the above-mentioned high trans content isoprene rubber (IR) specifically needs to have a trans-1,4 bond content of 95% or more, preferably 98% or more. More preferably, it is 99% or more. When the amount of trans-1,4 bond is too small, the improvement effect of the low temperature characteristics decreases.

  The above-mentioned high trans content isoprene rubber (IR) is not particularly limited as long as it satisfies the above trans content, and known products may be appropriately selected and used. For example, Kuraray "TP-301" etc. are mentioned.

  In the present invention, although rubber components containing NR and IR are used as described above, other rubbers such as known synthetic rubbers may be used in addition to the above-mentioned rubber components if necessary without departing from the object. You may use together. Specific examples thereof include butadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), isobutylene-isoprene rubber, silicone rubber (Q), acrylic rubber (ACM) And synthetic rubbers such as ethylene propylene rubber (EPDM) and acrylate butadiene rubber, and those obtained by modifying the molecular chain end of these synthetic rubbers, and the like, and one or two or more kinds thereof may be appropriately selected from these. You may use it.

Further, in the rubber composition of the present invention, a crosslinking agent is contained in the above rubber component, and the crosslinking agent is not particularly limited. For example, sulfur, citraconic imide compound, 1,6-bis (N, A known crosslinking agent or co-crosslinking agent such as N'-dibenzylthiocarbamoyldithio) hexane , bismaleimide compound, ZA (zinc diacrylate), ZMA (zinc methacrylate), ethylene glycol dimethacrylate, TAIC (hereinafter referred to as "crosslinking" Agent and co-crosslinking agent are collectively referred to as a crosslinking agent), and one type may be used alone, or two or more types may be blended depending on the combination.

（ここで、上記式のＲ¹としては、−Ｓ_x−Ｃ_nＨ_mＣｌ_pが挙げられ、ｘは０以上の整数、ｎは１以上の整数、ｍは０以上の整数、ｐは１以上の整数であり、かつ、ｍ＋ｐ＝２ｎ＋１を満たす。Ｓは硫黄原子、Ｃは炭素原子、Ｈは水素原子、Ｃｌは塩素原子を示すが、Ｃｌはその他のハロゲン族元素に置換が可能である。また、上記式のＲ²、Ｒ³としては、水素、アミノ基や炭素数１〜８の直鎖状、分岐状又は環状、或いはその組み合わせの炭化水素基が挙げられ、本置換基の位置と数には定めはない。） The rubber composition of the present invention preferably contains aromatic sulfonamides represented by the following structural formula. By blending the above-mentioned substances, it is more effective to use a vibration-proof rubber which is excellent in low temperature characteristics which could not be improved only by the conventionally adjusted ratio of sulfur to vulcanization accelerator and the kind of vulcanization accelerator. Can be obtained

(Here, R ¹ in the above-mentioned formula includes —S _x —C _n H _m Cl _p , x is an integer of 0 or more, n is an integer of 1 or more, m is an integer of 0 or more, p is 1 S is a sulfur atom, C is a carbon atom, H is a hydrogen atom, Cl is a chlorine atom, and Cl can be substituted with another halogen group element. Further, R ² and R ³ in the above formulas include hydrogen, an amino group, a linear, branched or cyclic C 1 -C 8 hydrocarbon group, or a combination thereof, and the position of this substituent And the number is not fixed.)

Specific examples of the above aromatic sulfonamides include N-phenyl-N- (monochloromethylthio) toluenesulfonamide, N-phenyl-N- (dichloromethylthio) toluenesulfonamide, N-phenyl-N- (dichloromethane) (Methylthio) toluenesulfonamide, N-phenyl-N- (monochloromethylthio) toluenesulfonamide, N-phenyl-N- (trichloromethylthio) benzenesulfonamide, N-phenyl-N- (dichloromethylthio) benzenesulfonamide, N- Phenyl-N- (trichloromethylthio) benzenesulfonamide, N-phenyl-N- (trichloroethylthio) benzenesulfonamide, N-phenyl-N- (trichloropropylthio) benzenesulfonamide and the like can be mentioned. In particular, it is preferable to use N-phenyl-N- (trichloromethylthio) benzenesulfonamide represented by the following formula.

  As a specific trade name of said N-phenyl-N- (trichloromethyl thio) benzene sulfonamide, "Vulkalent E / C" (made by LANXESS) etc. are mentioned.

  Although the compounding quantity of said aromatic sulfonamides is not restrict | limited in particular, Preferably it is 0.1-4 mass parts with respect to 100 mass parts of rubber components. If the amount is out of this range, improvement may not be observed in terms of low temperature properties and strength properties (hardness, tensile elongation, tensile strength).

  Furthermore, a vulcanization accelerator can be used for the rubber composition of the present invention. The type of the vulcanization accelerator is not particularly limited, but 2-mercaptobenzothiazole, dibenzothiazyl disulfide, N-cyclohexyl-2-benzothiazylsulfenamide, N-t-butyl-2-benzothiazyl Benzothiazole-based vulcanization accelerators such as sulfenamide, N-t-butyl-2-benzothiazylsulfenamide; guanidine-based vulcanization accelerators such as diphenylguanidine; tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutyl Thiuram-based vulcanization accelerators such as thiuram disulfide, tetradodecylthiuram disulfide, tetraoctylthiuram disulfide, tetrabenzylthiuram disulfide, dipentamethylenethiuram tetrasulfide; and dithios such as zinc dimethyldithiocarbamate Rubamin acid salt; and other zinc dialkyl dithiophosphate and the like.

  The above-mentioned vulcanization accelerator can be used in combination of one or more of a sulfenamide type, a thiuram type, a thiazole type, a guanidine type, a dithiocarbamate type and the like, for adjusting the vulcanization behavior (speed), etc. It is preferable to combine a thiuram type and / or thiazole type having a relatively high vulcanization acceleration ability with a guanidine and / or sulfenamide type vulcanization accelerator having a relatively moderate to low degree of vulcanization acceleration ability. Will be adopted. Specifically, a combination of tetramethylthiuram disulfide and N-cyclohexyl-2-benzothiazylsulfenamide, a combination of tetrabutylthiuram disulfide and N-t-butyl-2-benzothiazylsulfenamide, dibenzo Examples include combinations of thiazyl disulfide and diphenyl guanidine. However, the combination of the vulcanization accelerator is not limited to the above combination. The total blending amount of the vulcanization accelerator is preferably 0.2 to 10 parts by mass with respect to 100 parts by mass of the rubber component.

  Although the rubber composition of the present invention may or may not contain sulfur, the inclusion of sulfur can further improve various rubber properties relatively. When sulfur is contained, the blending amount of sulfur is preferably 0.1 to 1.5 parts by mass, and more preferably 0.2 to 1.0 parts by mass with respect to 100 parts by mass of the rubber component. When the compounding amount exceeds 1.5 parts by mass, the heat aging resistance may be deteriorated.

  In the present invention, from the viewpoint of promoting the vulcanization, a vulcanization accelerating assistant such as zinc white (ZnO) or a fatty acid can be blended. The fatty acid may be any saturated, unsaturated, linear or branched fatty acid, and the carbon number of the fatty acid is not particularly limited, and is, for example, a fatty acid having 1 to 30 carbon atoms, preferably 15 to 30 carbon atoms, Specifically, cyclohexane acid (cyclohexanecarboxylic acid), naphthenic acid such as alkylcyclopentane having a side chain, hexanoic acid, octanoic acid, decanoic acid (including branched carboxylic acids such as neodecanoic acid), dodecanoic acid, tetradecanoic acid And saturated fatty acids such as hexadecanoic acid and octadecanoic acid (stearic acid), unsaturated fatty acids such as methacrylic acid, oleic acid, linoleic acid and linolenic acid, and resin acids such as rosin, tall oil acid and abietic acid. These may be used singly or in combination of two or more. In the present invention, zinc flower and stearic acid can be suitably used. The compounding amount of these assistants is preferably 1 to 10 parts by mass, more preferably 2 to 7 parts by mass with respect to 100 parts by mass of the rubber component. If the compounding amount is more than 10 parts by mass, there is a possibility that deterioration of workability and deterioration of the dynamic magnification etc. may be caused, and if it is less than 1 part by mass, there is a possibility of vulcanization delay and the like.

  As the oil, known ones can be used, and it is not particularly limited. Specifically, process oils such as aromatic oils, naphthenic oils and paraffin oils, vegetable oils such as coconut oil, synthetic oils such as alkylbenzene oils, and castor oil Oil etc. can be used. In the present invention, naphthenic oil can be suitably used. These can be used singly or in combination of two or more. The blending amount of oil is not particularly limited, but can be approximately 2 to 80 parts by mass with respect to 100 parts by mass of the rubber component. If the compounding amount is out of the above range, the kneading workability may be deteriorated. When an oil-extended rubber is used as the rubber component, the total amount of the oil contained in the rubber and the oil separately added at the time of mixing may be in the above range.

  As the carbon black, known ones can be used, and it is not particularly limited. For example, carbon black such as FEF, SRF, GPF, HAF, ISAF, SAF, FT, MT, etc. can be mentioned, and the present invention In the above, FEF can be suitably used. Moreover, these carbon blacks may be used individually by 1 type, and may use 2 or more types together. The compounding amount of these carbon blacks is usually 15 to 80 parts by mass, preferably 20 to 60 parts by mass with respect to 100 parts by mass of the rubber component. If the compounding amount exceeds 80 parts by mass, the workability may be deteriorated, and if less than 15 parts by mass, the adhesion may be deteriorated.

  As an antiaging agent, a well-known thing can be used, Although it does not restrict | limit in particular, A phenolic anti-aging agent, an imidazole anti-aging agent, an amine anti-aging agent etc. can be mentioned. The blending amount of these antioxidants is usually 1 to 10 parts by mass, preferably 2 to 7 parts by mass, with respect to 100 parts by mass of the rubber component. The antiaging agent can be used alone or in combination of two or more.

  In addition, with respect to the above rubber component, waxes, antioxidants, fillers, foaming agents, plasticizers, oils, lubricants, which are usually used in the rubber industry, as needed, as long as the effects of the present invention are not impaired. Additives such as tackifiers, petroleum resins, ultraviolet light absorbers, dispersants, compatibilizers, homogenizing agents, and vulcanization retarders can be appropriately blended.

  When the rubber composition of the present invention is obtained, the method of blending the above components is not particularly limited, and all the component materials may be blended at one time and kneaded, or each component may be divided into two or three stages. You may mix | blend and knead | mix. In addition, kneaders, such as a roll, an internal mixer, and a Banbury mixer, can be used in the case of kneading | mixing. Further, when forming into a sheet shape, a band shape or the like, a known forming machine such as an extrusion molding machine or a press machine may be used.

  Further, the curing conditions for curing the rubber composition are not particularly limited, but generally, the curing conditions of 140 to 180 ° C. for 5 to 120 minutes can be adopted.

  The anti-vibration rubber of the present invention is obtained by vulcanizing the above-mentioned rubber composition, but as the anti-vibration rubber, for example, a portion which becomes high temperature such as a totional damper of an automobile, an engine mount, or a muffler hanger Are preferably used, but not limited thereto.

  Hereinafter, the present invention will be described in detail by way of Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Examples 1 to 12, Reference Example I, and Comparative Examples 1 to 7]
The vibration-proof rubber compositions of Examples 1 to 12, Reference Example I, and Comparative Examples 1 to 7 were added under predetermined conditions by kneading and vulcanizing with the composition shown in each table of Tables 1 and 2 below. It was vulcanized and cured to produce a sheet molding of length 120 mm × width 120 mm × thickness 2 mm. This sheet was used as an evaluation body of the vibration-proof rubber of the present invention. The tensile elongation (Eb) and the tensile strength (Tb) of the obtained rubber sheet were evaluated. And about evaluation of each characteristic, in Table 1, Comparative Example 1 and Table 2 were described in each table of Table 1 and Table 2 by the index (INDEX) display which made Comparative Example 4 the reference value. In addition, about the rubber characteristic currently displayed as an index (INDEX), the index when the data value of the comparative examples 1 and 4 used as a reference | standard is set as 100 is described. The sample shape for measurement of low temperature characteristics and the evaluation conditions are described below.

[Tensile elongation (Eb)]
It conformed to JIS K 6251. The index when the data value of Comparative Example 1 is 100 is described. The tensile elongation (Eb) shows that the higher the index value, the better.
[Tensile strength (Tb)]
It conformed to JIS K 6251. The index when the data value of Comparative Example 1 is 100 is described. The tensile strength (Tb) indicates that the higher the index value, the better.

Low temperature characteristics
A cylindrical rubber sample having a diameter of 30 mm and a height of 30 mm was prepared, and in accordance with JIS K 6385, Kd was measured at 100 Hz (this is referred to as initial Kd). Then, after exposure for 10 days at -35 ° C., Kd was rapidly measured under the same conditions as described above (this is referred to as Kd after low temperature exposure). The low temperature characteristics are determined by Kd / initial Kd after low temperature exposure, and Table 1 describes indexes when the low temperature characteristic value of Comparative Example 4 is 100 in Comparative Example 1 and Table 2. The smaller the change in Kd after the low temperature exposure, the better the low temperature characteristics, and the smaller the index value, the better the low temperature characteristics.

Details of the above formulation are as follows.
Rubber component · Natural rubber (NR): "RSS # 4"
・ High trans content isoprene rubber (IR): Kuraray “TP-301” (trans-1,4 bond content 99%)
Isoprene rubber (IR): Kraton “Cariflex IR 0307” cis-1,4 bond content: 90% or more
Use carbon black FEF carbon black. Tokai Carbon "Seast F"
Stearic acid "Stearic acid 50S" made by Nippon Rika
Zinc flower brand name "No. 3 zinc flower" (made by Hakusui Tech Co., Ltd.)
Anti-aging agent: RD
2,2,4-trimethyl-1,2-dihydroquinoline polymer, Nouchi 224, manufactured by Ouchi Shinko Chemical Co., Ltd.
Anti-aging agent: 6C
N-phenyl-N '-(1,3-dimethylbutyl) -p-phenylenediamine, "NOCRAC 6C" manufactured by Ouchi Shinko Chemical Co., Ltd.
MICROCRYSTALLINE WAX
Seiko Co., Ltd. "Santheite S"
NAPHTEN OIL SUN REFINING AND MARKETING COMPANY "Sunthene 4240"
Sulfur brand name "powder sulfur" (made by Tsurumi Chemical Co., Ltd.)
N, N'-m-phenylenebismaleimide Ouchi Emerging Chemical Company product "Barnock PM"
Thiuram-based accelerator: TT
Brand name "Axel TMT-PO" (made by Kawaguchi Chemical Industry)
Sulfenamide-based accelerator: CZ
Brand name "Noxceler CZ-G" (made by Ouchi Shinko Chemical Co., Ltd.)
N-phenyl-N- (trichloromethylthio) benzenesulfonamide trade name "Vulkalent E / C" (manufactured by LANXESS)

<Judgment of rate of change with reference value>
With respect to the rubber characteristics of each example and comparative example, the rate of change in comparison with the reference value (comparative example 1 and comparative example 4 ) in each table was determined based on the following criteria, and the same was written in each table.
改良 20% or more improvement ○ 10% or more and less than 20% improvement-No change (less than 10% change)
悪 化 Deterioration of 10% or more and less than 20% × Deterioration of 20% or more

From the results of Table 1, the following can be seen.
Examples 1 to 8 show that the low temperature characteristics can be improved as compared with Comparative Example 1, and the strength characteristics ( tensile elongation and tensile strength) can be well maintained. In particular, in each of Examples 1 to 8, an improvement of 10 points or more in index display is observed in the low temperature characteristics.
On the other hand, in Comparative Example 2, the low temperature characteristics show deterioration of 10 points or more in index display. Comparative Example 3 shows a deterioration in tensile strength (Tb) as compared to Comparative Example 1.

From the results of Table 2, the following can be seen.
Examples 9 to 12 show that the low temperature characteristics can be improved and the tensile elongation and tensile strength can be maintained well, as compared with Comparative Example 4. In particular, Examples 9 to 12 show an improvement of 10 points or more in index display in the low temperature characteristics, and Example 10 shows an improvement of 10 points or more in index display of tensile strength (Tb). On the other hand, in Comparative Example 5, in comparison with Comparative Example 4, the tensile elongation (Eb) shows a deterioration of 10 points or more in index display, and in Comparative Example 6, the tensile elongation (Eb) and tensile strength as compared with Comparative Example 4 (Tb) has not been improved. In Comparative Example 7, in comparison with Comparative Example 4, the tensile strength (Tb) shows a deterioration of 10 points or more in index display.

Claims (5)

Natural rubber, high trans content isoprene rubber having a trans-1,4 bond content of 95% or more, sulfur, and a rubber composition for automotive vibration proof rubber characterized by containing aromatic sulfonamides having the following structural formula object.

(Here, as R ¹ in the above formula, -S _x -C _n H _m Cl _p is mentioned, x = 1 , n is an integer of 1 or more, m is an integer of 0 or more, p is an integer of 1 or more And m + p = 2n + 1, S represents a sulfur atom, C represents a carbon atom, H represents a hydrogen atom, and Cl represents a chlorine atom, but Cl may be substituted with another halogen group element. Examples of R ² and R ^{3 in the} above formula include hydrogen, an amino group, and a linear, branched or cyclic C 1 -C 8 hydrocarbon group or a combination thereof.   The rubber composition according to claim 1, wherein the blending ratio of the high trans content isoprene rubber is less than 20% by mass with respect to the rubber component of the above natural rubber (NR) and the high trans content isoprene rubber (IR). Rubber composition. The blending amount of the aromatic sulfonamides is 0.1 to 4 parts by mass with respect to 100 parts by mass of the rubber component containing the natural rubber (NR) and the high trans content isoprene rubber (IR). The rubber composition for vibration proof rubbers for motor vehicles as described.   The above aromatic sulfonamides are N-phenyl-N- (monochloromethylthio) toluenesulfonamide, N-phenyl-N- (dichloromethylthio) toluenesulfonamide, N-phenyl-N- (trichloromethylthio) benzenesulfonamide, Compounds selected from the group of N-phenyl-N- (dichloromethylthio) benzenesulfonamide, N-phenyl-N- (trichloroethylthio) benzenesulfonamide, and N-phenyl-N- (trichloropropylthio) benzenesulfonamide The rubber composition for vibration-proof rubber for motor vehicles according to any one of claims 1 to 3, which is   The vibration-proof rubber for motor vehicles which hardens the rubber composition of any one of Claims 1-4.