JP4681536B2 - Rubber composition for sidewall and method for producing the same - Google Patents

Description

  The present invention relates to a rubber composition for a sidewall and a method for producing the same.

  Conventionally, rubber compositions for tire sidewalls are blended with butadiene rubber (BR) in order to improve flex crack growth resistance in addition to natural rubber (NR) exhibiting excellent tear strength, and weather resistance. And carbon black has been used to improve reinforcement.

However, in recent years, environmental issues have become more important, regulations on CO ₂ emission control have been strengthened, and oil resources are limited and the supply amount has been decreasing year by year. The price is expected to rise, and there is a limit to the use of raw materials derived from petroleum resources such as BR and carbon black. Therefore, assuming that the oil will be depleted in the future, it is necessary to use non-oil resources such as NR and silica. However, in that case, there is a problem that performance equal to or higher than the resistance to bending cracking and reinforcement obtained by the use of petroleum resources that have been conventionally used cannot be obtained.

Patent Document 1 discloses an eco-tire having characteristics that are comparable to conventional tires by increasing the ratio of non-oil resources in the tire by using a predetermined non-petroleum resource. Also, the resistance to flex crack growth was not improved in a well-balanced manner.
JP 2003-63206 A

  The present invention can be environmentally friendly and can be prepared for a future reduction in the supply of oil, and further improves the tear strength, flex crack growth resistance and durability in a well-balanced manner without increasing the hardness. An object of the present invention is to provide a rubber composition for sidewalls and a method for producing the same.

  The present invention is derived from a non-petroleum resource having 15 to 60 parts by weight of silica and a double bond with respect to 100 parts by weight of a rubber component containing 30 to 80% by weight of natural rubber and 20 to 70% by weight of epoxidized natural rubber. The present invention relates to a rubber composition for a sidewall containing 2 to 20 parts by weight of a plasticizer.

  The plasticizer derived from non-petroleum resources having a double bond preferably has an iodine value of 90 or more.

  The side wall rubber composition can be produced by (1) a step of kneading natural rubber, silica and a plasticizer derived from a non-petroleum resource having a double bond, and (2) discharged in step (1). It is preferable to include a step of kneading the kneaded material and the epoxidized natural rubber.

  The rubber composition for sidewalls includes (1) a step of producing a master batch by kneading an epoxidized natural rubber and a plasticizer derived from a non-petroleum resource having a double bond, and (2) a natural rubber and silica. It is preferable to include a step of kneading, and (3) a step of kneading the master batch discharged in step (1) and the kneaded material discharged in step (2).

The sidewall rubber composition preferably further contains 4 to 16 parts by weight of a silane compound satisfying the following general formula with respect to 100 parts by weight of silica.
_Xn- Si-Y _4-n
(Wherein X is an alkoxy group, Y is a phenyl group or an alkyl group, and n is an integer of 1 to 3)

  The present invention also relates to a tire having a sidewall using the rubber composition for a sidewall.

  According to the present invention, it is possible to give consideration to the environment by containing a predetermined amount of a rubber component including natural rubber and epoxidized natural rubber, silica and a plasticizer derived from a non-petroleum resource having a double bond. Further, it is possible to provide a rubber composition for a sidewall and a method for producing the same, which can improve the tear strength and the bending crack growth resistance in a well-balanced manner without increasing the hardness. .

  The rubber composition for a side wall of the present invention contains a rubber component, silica, and a plasticizer derived from non-petroleum resources having a double bond.

  The rubber component includes natural rubber (NR) and epoxidized natural rubber (ENR).

  The NR may be one generally used in the rubber industry such as TSR20 and RSS # 3.

  The content of NR in the rubber component is 30% by weight or more, preferably 40% by weight or more. When the content of NR is less than 30% by weight, the crack growth resistance deteriorates. The content of NR is 80% by weight or less, preferably 70% by weight or less. When the NR content exceeds 80% by weight, the crack growth resistance deteriorates.

  As ENR, commercially available ENR may be used, or NR may be epoxidized. The method for epoxidizing NR is not particularly limited, and can be carried out using a method such as a chlorohydrin method, a direct oxidation method, a hydrogen peroxide method, an alkyl hydroperoxide method, or a peracid method. Examples of the peracid method include a method of reacting NR with an organic peracid such as peracetic acid or performic acid.

  The epoxidation rate of ENR is preferably 5 mol% or more, and more preferably 10 mol% or more. When the epoxidation rate of ENR is less than 5 mol%, the effect of ENR being compatible with NR tends to decrease. Further, the ENR epoxidation rate is preferably 60 mol% or less, and more preferably 50 mol% or less. If the epoxidation rate of ENR exceeds 60 mol%, the rubber strength tends to be insufficient.

  The content of ENR in the rubber component is 20% by weight or more, preferably 30% by weight or more. When the content of ENR is less than 20% by weight, the crack growth resistance is lowered. The ENR content is 70% by weight or less, preferably 60% by weight or less. If the ENR content exceeds 70% by weight, the crack growth resistance deteriorates.

  In addition to NR and ENR, the rubber component includes styrene butadiene rubber (SBR), butadiene rubber (BR), butyl rubber (IIR), halogenated butyl rubber (X-IIR), isomonoolefin and p-alkylstyrene. Rubbers such as copolymer halides can also be included, but they can be obtained from non-petroleum resources, are environmentally friendly, and can be prepared for future reductions in the supply of petroleum. It is preferable not to contain rubber.

  There is no restriction | limiting in particular as a silica, The thing generally used in the rubber industry can be used.

  The content of silica is 15 parts by weight or more, preferably 20 parts by weight or more with respect to 100 parts by weight of the rubber component. When the content of silica is less than 15 parts by weight, the rubber strength is lowered, and a cut is generated by an external stimulus to the tire side surface, resulting in a decrease in wear resistance. The content of silica is 60 parts by weight or less, preferably 40 parts by weight or less. When the content of silica exceeds 60 parts by weight, the hardness increases excessively and crack growth resistance deteriorates.

The sidewall rubber composition of the present invention preferably contains a silane compound together with silica. By containing the silane compound, the resistance to flex crack growth and durability can be improved. Examples of the silane compound include those represented by the following formula.
_Xn- Si-Y _4-n
(Wherein X is an alkoxy group, Y is a phenyl group or an alkyl group, and n is an integer of 1 to 3)

  In the formula, X is an alkoxy group, and is preferably a methoxy group or an ethoxy group because it easily reacts with silica, and more preferably an ethoxy group because it has a high flash point.

Y is a phenyl group or an alkyl group. When Y is an alkyl group, for example, a methyl group (—CH ₃ ), for example, methyltriethoxysilane has a flash point of 8 ° C., a hexyl group (—CH ₂ ( In the case of CH ₂ ) ₄ CH ₃ ), for example, hexyltriethoxysilane has a flash point as low as 81 ° C., whereas when Y is a phenyl group, the flash point is as high as 111 ° C. Groups are preferred.

  n is an integer of 1 to 3. When n is 0, the silane compound does not have an alkoxy group and tends not to react with silica. Moreover, when n is 4, it tends to be difficult to be compatible with rubber. Note that n is preferably 3 because it is highly reactive with silica.

  Examples of silane compounds satisfying the above formula include methyltrimethoxysilane (KBM13 manufactured by Shin-Etsu Chemical Co., Ltd.), dimethyldimethoxysilane (KBM22 manufactured by Shin-Etsu Chemical Co., Ltd.), and phenyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd.). KBM103 manufactured by Shin-Etsu Chemical Co., Ltd.), methyltriethoxysilane (KBE13 manufactured by Shin-Etsu Chemical Co., Ltd.), dimethyldiethoxysilane (KBE22 manufactured by Shin-Etsu Chemical Co., Ltd.) Etc.), phenyltriethoxysilane (KBE103 manufactured by Shin-Etsu Chemical Co., Ltd.), diphenyldiethoxysilane (KBE202 manufactured by Shin-Etsu Chemical Co., Ltd.), hexyltrimethoxysilane (KBM3063 manufactured by Shin-Etsu Chemical Co., Ltd.) , Hexyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) BE3063 etc.), etc. KBM3103, KBM3103C made decyl trimethoxysilane (Shin-Etsu Chemical Co.) and the like, such as. Of these, phenyltriethoxysilane is preferred because of its high reactivity with silica and high flash point.

  The content of the silane compound is preferably 4 parts by weight or more and more preferably 8 parts by weight or more with respect to 100 parts by weight of silica. When the content of the silane compound is less than 4 parts by weight, sufficient bending crack growth resistance, tear strength and durability tend not to be obtained. Further, the content of the silane compound is preferably 16 parts by weight or less, and more preferably 12 parts by weight or less. When the content of the silane compound exceeds 16 parts by weight, the tear strength tends to decrease.

  In the present invention, a silane coupling agent can be used in combination with silica and a silane compound. There is no restriction | limiting in particular as a silane coupling agent, What is generally used in rubber industry, such as sulfide type silane coupling agents like Si69, can be used.

  The content of the silane coupling agent is preferably 4 parts by weight or more and more preferably 8 parts by weight or more with respect to 100 parts by weight of silica. When the content of the silane coupling agent is less than 4 parts by weight, the rubber strength tends to decrease. Further, the content of the silane coupling agent is preferably 20 parts by weight or less, and more preferably 16 parts by weight or less. When the content of the silane coupling agent exceeds 20 parts by weight, the rubber strength tends to decrease.

  Examples of plasticizers derived from non-petroleum resources having a double bond include linseed oil, soybean oil, oleyl alcohol, terpene resins, and the like. Of these, linseed oil and / or terpene-based resins are preferred because they are excellent in crack growth resistance. Aroma oil, paraffin oil, and the like are plasticizers derived from petroleum resources, and are not suitable for the purpose of the present application to consider the environment.

  The iodine value of the plasticizer derived from non-petroleum resources having a double bond is preferably 90 or more, more preferably 130 or more, and still more preferably 190 or more. When the iodine value of a plasticizer derived from a non-petroleum resource having a double bond is less than 90, there is a tendency that a sufficient improvement effect of crack growth resistance cannot be obtained.

  The content of the plasticizer derived from non-petroleum resources having a double bond is 2 parts by weight or more, preferably 4 parts by weight or more, more preferably 5 parts by weight or more with respect to 100 parts by weight of the rubber component. If the content of the plasticizer having a double bond derived from a non-petroleum resource is less than 2 parts by weight, a sufficient improvement effect of crack growth resistance cannot be obtained by blending a plasticizer derived from a non-petroleum resource having a double bond. . The content of the plasticizer derived from non-petroleum resources having a double bond is 20 parts by weight or less, preferably 15 parts by weight or less. When the content of the plasticizer derived from non-petroleum resources having a double bond exceeds 20 parts by weight, the rubber strength decreases.

  In addition to the rubber component, silica, silane compound, silane coupling agent, and plasticizer derived from non-petroleum resources having a double bond, the rubber composition for sidewalls of the present invention is conventionally blended in the rubber industry. Agents such as wax, various anti-aging agents, stearic acid, zinc oxide, sulfur, various vulcanization accelerators and the like can be appropriately blended.

  The rubber composition for a side wall of the present invention is used as a side wall in a tire because the resistance to bending crack growth is particularly improved.

  The manufacturing method (manufacturing method 1) of the rubber composition for sidewalls in the first aspect of the present invention is obtained by a manufacturing method including the following steps 1 and 2.

  In step 1, NR, silica and a plasticizer having a double bond are kneaded.

  In step 2, the kneaded material and ENR discharged in step 1 are kneaded.

  In step 1, compounding agents such as a silane compound, a silane coupling agent, a wax, various anti-aging agents, stearic acid, and zinc oxide can also be blended.

  In addition, by kneading ENR not in step 1 but in step 2, an effect of improving crack growth resistance can be obtained.

  Moreover, the manufacturing method (manufacturing method 2) of the rubber composition for sidewalls in the second aspect of the present invention is obtained by a manufacturing method including the following steps 1, 2, and 3.

  In step 1, a masterbatch is prepared by mixing ENR and a plasticizer having a double bond.

  In step 2, NR and silica are kneaded.

  In step 3, the master batch discharged in step 1 and the kneaded material discharged in step 2 are kneaded.

  In step 1, the content of the plasticizer having a double bond when producing a master batch is preferably 5 parts by weight or more, more preferably 10 parts by weight or more with respect to 100 parts by weight of ENR. When the content of the plasticizer having a double bond is less than 5 parts by weight, there is a tendency that a sufficient improvement effect of crack growth resistance by the blending of the plasticizer having a double bond cannot be obtained. The content of the plasticizer having a double bond is preferably 50 parts by weight or less, and more preferably 30 parts by weight or less. When the content of the plasticizer having a double bond exceeds 50 parts by weight, the viscosity is excessively lowered and the workability tends to be remarkably lowered.

  In Step 2, compounding agents such as a silane compound, a silane coupling agent, a wax, various anti-aging agents, stearic acid, and zinc oxide can also be blended.

  By producing a master batch in Step 1 and kneading in Step 3, the effect of improving crack growth resistance can be obtained.

  Using the rubber composition for a sidewall of the present invention, the rubber composition for a sidewall of the present invention in which the compounding agent is blended by the production method as necessary according to the production method 1, 2 or a normal method, An unvulcanized tire is formed by extruding in accordance with the shape of the sidewall of the tire at an unvulcanized stage and molding on a tire molding machine by a normal method. The unvulcanized tire is heated and pressurized in a vulcanizer to obtain the tire of the present invention.

  By using the rubber composition for a sidewall of the present invention, the tire of the present invention can be made into an eco-tire that can be considered for the environment and can be prepared for a future decrease in the amount of petroleum supply.

  The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

Below, the various chemical | medical agents used by the Example and the comparative example are demonstrated collectively.
Natural rubber (NR): TSR20
Epoxidized natural rubber (ENR): ENR25 (Epoxidation rate: 25 mol%) manufactured by Kampung Langley
Butadiene rubber (BR): BR150B manufactured by Ube Industries, Ltd.
Carbon black: Dia Black E (N550) manufactured by Mitsubishi Chemical Corporation
Silica: Ultrazil VN3 manufactured by Degussa (nitrogen adsorption specific surface area: 210 m ² / g)
Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Silane compound: KBE-103 (phenyltriethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd.
Plasticizer derived from non-petroleum resources without double bond: Epoxidized soybean oil (Iodine value: 3) manufactured by Kao Corporation
Plasticizer derived from non-petroleum resources having a double bond 1: N / B linseed oil manufactured by Nisshin Oilio Group Co., Ltd. (iodine number: 190)
Plasticizer derived from non-petroleum resources having a double bond 2: Oleyl # 900 (oleyl alcohol, iodine value: 90) manufactured by Kyowa Technos Co., Ltd.
Plasticizer derived from non-petroleum resources having a double bond 3: Dimaron (terpene resin, iodine value: 207) manufactured by Yashara Chemical Co., Ltd.
Aroma oil: Process X-140 manufactured by Japan Energy Co., Ltd.
Petroleum resin: SP1068 resin wax manufactured by Nippon Shokubai Co., Ltd .: Ozoace 0355 manufactured by Nippon Seiwa Co., Ltd. (paraffin wax)
Masterbatch 1: 20 parts by weight plasticizer derived from non-petroleum resources having no double bond to 100 parts by weight of ENR Masterbatch 2: Plasticity derived from non-petroleum resources having a double bond to 100 parts by weight of ENR Masterbatch containing 20 parts by weight of agent 1: Masterbatch containing 20 parts by weight of plasticizer 2 derived from non-petroleum resources having a double bond to 100 parts by weight of ENR: Double bond to 100 parts by weight of ENR Anti-aging agent containing 20 parts by weight of plasticizer 3 derived from non-petroleum resources: Antigen 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamide) manufactured by Sumitomo Chemical Co., Ltd.
Stearic acid: Tsubaki stearic acid manufactured by Nippon Oil & Fats Co., Ltd.
Zinc oxide: Sulfur manufactured by Mitsui Mining & Smelting Co., Ltd .: Vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd .: Noxeller CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical

Examples 1 to 10 and Comparative Examples 1 to 11
In accordance with the formulation shown in Table 1, using a 1.7L Banbury mixer manufactured by Kobe Steel Co., Ltd., so that the chemicals other than master batches 1 to 4, sulfur and vulcanization accelerator are filled to 58%. The resulting mixture was kneaded at 80 rpm until reaching 140 ° C. to obtain a kneaded product 1 (step 1). Next, after discharging once, using a 1.7L Banbury mixer manufactured by Kobe Steel Co., Ltd., master batches 1 to 4 so that the kneaded product 1 obtained in step 1 and the filling rate become 58%. The resulting mixture was kneaded until reaching 140 ° C. to obtain a kneaded product 2 (step 2). Thereafter, using an 8-inch roll, the kneaded product 2, the sulfur and the vulcanization accelerator obtained in step 2 were kneaded for 2 minutes or more under a condition of 100 ° C. or lower to obtain an unvulcanized rubber composition ( Step 3). Furthermore, the vulcanized rubber compositions of Examples 1 to 10 and Comparative Examples 1 to 11 were prepared by press vulcanizing the unvulcanized rubber composition obtained in Step 3 for 20 minutes at 160 ° C. . In Comparative Example 9, ENR was not kneaded in step 1 but kneaded in step 2.

(Hardness measurement)
The hardness was measured with a spring type A according to JIS-K6253 “Method for testing hardness of vulcanized rubber and thermoplastic rubber”.

(Tear test)
In accordance with JIS-K6252 “vulcanized rubber and thermoplastic rubber—how to determine tear strength”, the tear strength (N / mm) was measured by using an angle-shaped test piece without cutting.

(Flexible crack growth resistance)
According to JIS-K6260 “Dematcher bending crack growth test method for vulcanized rubber and thermoplastic rubber”, the number of times until the vulcanized rubber composition breaks 1 mm under the condition of 25 ° C. was measured. Here, log (10,000 times / mm) is the logarithm of the number of measurements until breakage occurs. It shows that bending crack growth resistance is so favorable that a numerical value is large. Here, 70% and 110% represent elongation rates with respect to the surface length of the original vulcanized rubber composition.

(durability)
The unvulcanized rubber composition is molded into a sidewall shape and bonded together with other tire members to form an unvulcanized tire, which is then press vulcanized for 20 minutes at 160 ° C. (Size: 195 / 65R15) was produced.

Using a drum (outer diameter: 1.7 m), the manufactured tire was loaded under the conditions of rim (15 × 6.00 JJ), load (6.96 kN), internal pressure (150 kPa), speed (80 km / h). And continuously running until a crack occurred in the sidewall portion, and the distance (crack generation distance) when the crack occurred was measured. Thereafter, the durability index of Comparative Example 2 was set to 100, and the crack generation distance of each formulation was indicated by an index according to the following calculation formula.
(Durability Index) = (Crack generation distance of each formulation) / (Crack generation distance of Comparative Example 2) × 100

  The test results are shown in Table 1.

  Comparative Example 1 is a rubber composition containing a conventional carbon black compound.

  In Examples 1-2, 5-6, and 9, by blending a plasticizer derived from a non-petroleum resource having a predetermined rubber component and a double bond, the tear strength and the flex crack growth resistance are increased without increasing the hardness. Property and durability could be improved in a well-balanced manner.

  In Examples 3 to 4, 7 to 8, and 10, a master batch kneaded with a plasticizer derived from a non-petroleum resource having ENR and a double bond was added in Step 2 to further increase the tear strength and the flex crack resistance. The growth and durability could be improved.

  In Comparative Examples 2 to 8, a plasticizer derived from a non-petroleum resource having a double bond is not blended, and not only the hardness is increased, but also the tear strength, the flex crack growth resistance and the durability are balanced. It did not improve, and in particular, the durability was insufficient.

  In Comparative Examples 9 to 10, a plasticizer was blended, but since it was not a plasticizer derived from non-petroleum resources having a double bond, the results were insufficient particularly in terms of tear strength and durability.

  In Comparative Example 11, since ENR was not blended, it was not possible to improve any of the tear strength, flex crack growth resistance, and durability.

Claims (7)

For 100 parts by weight of a rubber component containing 30 to 80% by weight of natural rubber and 20 to 70% by weight of epoxidized natural rubber,
It is a rubber composition for a sidewall containing 15 to 60 parts by weight of silica and 2 to 20 parts by weight of a plasticizer derived from a non-petroleum resource having a double bond ,
A rubber composition for a sidewall, wherein the plasticizer derived from a non-petroleum resource having a double bond is oleyl alcohol and / or a terpene resin . For 100 parts by weight of a rubber component containing 30 to 80% by weight of natural rubber and 20 to 70% by weight of epoxidized natural rubber,
15-60 parts by weight of silica, and
A rubber composition for a sidewall containing 2 to 20 parts by weight of a plasticizer derived from a non-petroleum resource having a double bond,
A rubber composition for a sidewall, wherein the plasticizer derived from a non-petroleum resource having a double bond has an iodine value of 190 or more. (1) A step of kneading natural rubber, silica and a plasticizer derived from a non-petroleum resource having a double bond, and (2) a step of kneading the kneaded product discharged in step (1) and the epoxidized natural rubber. The manufacturing method of the rubber composition for sidewalls of Claim 1 or 2 containing these. (1) a step of producing a masterbatch by kneading an epoxidized natural rubber and a plasticizer derived from a non-petroleum resource having a double bond;
(2) A step of kneading natural rubber and silica, and (3) a step of kneading the masterbatch discharged in step (1) and the kneaded material discharged in step (2). The manufacturing method of the rubber composition for side walls of description. Furthermore, with respect to 100 parts by weight of silica,
The rubber composition for a sidewall according to claim 1 or 2, comprising 4 to 16 parts by weight of a silane compound satisfying the following general formula.
_Xn- Si-Y _4-n
(Wherein X is an alkoxy group, Y is a phenyl group or an alkyl group, and n is an integer of 1 to 3) A tire having a sidewall using the rubber composition for a sidewall according to claim 1, 2 or 5. A tire having a sidewall using the rubber composition for a sidewall obtained by the production method according to claim 3 or 4.