JP2007070439A - Rubber composition and tire using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition further excellent in scorch stability, compared with a rubber composition produced by a conventional technique and excellent in reversion resistance and heat resistance such as heat generation durability. <P>SOLUTION: The rubber composition is obtained by compounding, based on 100 pts.mass rubber component composed of at least one kind of rubber selected from a natural rubber, a synthetic rubber with 20-150 pts.mass reinforcing filler and 0.01-30 pts.mass compound represented by formula (I): X-R<SP>1</SP>-Y [wherein R<SP>1</SP>is a divalent saturated aliphatic hydrocarbon group, a divalent aromatic hydrocarbon group or a divalent heterocyclic group; X and Y are each independently a monovalent functional group having a nitrogen-containing 1,3-dipole]. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rubber composition and a tire using the rubber composition, and particularly to a rubber composition having excellent heat resistance such as reversion resistance and heat generation durability in addition to excellent scorch stability and the rubber. The present invention relates to a tire having high heat resistance using the composition for at least one of tire members.

  Conventionally, as a technique for improving heat resistance such as vulcanization resistance and heat generation durability of a vulcanizable rubber composition used for rubber products such as tires, a vulcanization accelerator for sulfur as a vulcanizing agent is used. A technique for increasing the blending amount and a technique for blending a thiuram vulcanization accelerator as a vulcanization accelerator are known.

Further, as a cross-linking agent capable of forming a long-chain cross-linked structure represented by -S- (CH ₂ ) ₆ -S-, Flexis Durlink HTS (see Patent Document 1) and Bayer Vulcuren KA9188 (Patent Document 2). It is known that the reversion resistance of the rubber composition can be improved by blending these crosslinking agents into the rubber composition.

JP 58-17132 A JP 2001-2833 A

  However, in the conventional method, when trying to improve the reversion resistance and heat generation durability of the rubber composition, problems such as inability to secure the scorch stability occur, and the scorch stability and resistance of the rubber composition are increased. There was still room for improvement because it was not possible to sufficiently balance reversion and heat generation durability. Here, in the process of producing a rubber product from the rubber composition, if scorch is generated before vulcanization, there arises a problem that it becomes difficult to produce a rubber product having desired physical properties.

  Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art, and have better scorch stability than the rubber composition obtained by the conventional technique, and heat resistance such as vulcanization resistance and heat generation durability. It is in providing the rubber composition excellent in. Another object of the present invention is to provide a tire having high heat resistance using such a rubber composition.

  As a result of intensive studies to achieve the above object, the present inventor has formulated a compound having two nitrogen-containing 1,3-dipoles together with a reinforcing filler in a specific compounding amount with respect to the rubber component. The present inventors have found that the scorch stability of the rubber composition, and further, the reversion resistance and heat generation durability of the rubber composition after vulcanization are greatly improved, and the present invention has been completed.

That is, the rubber composition of the present invention comprises 20 to 150 parts by mass of a reinforcing filler and 100 parts by mass of the following formula (I) with respect to 100 parts by mass of a rubber component composed of at least one of natural rubber and synthetic rubber.
X-R ¹ -Y (I)
[Wherein, R ¹ is a divalent saturated aliphatic hydrocarbon group, a divalent aromatic hydrocarbon group, or a divalent heterocyclic group, and X and Y are each independently nitrogen-containing 1, It is a monovalent functional group having a 3-dipole] and is compounded with 0.01 to 30 parts by mass of a compound represented by Here, the monovalent functional group having a nitrogen-containing 1,3-dipole has a positive charge and a negative charge (that is, has a dipole) in the functional group, and the charge has three A monovalent nitrogen-containing functional group existing on a conjugated atom, in other words, a structure in which one atom or atomic group not related to a dipole is removed from a 1,3-dipole compound containing nitrogen. It is a monovalent functional group.

In the compound of the above formula (I) blended in the rubber composition of the present invention, R ¹ is preferably a divalent saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms, a phenylene group or a naphthylene group.

［式(IIa)及び式(IIb)中のＲ²、式(IIa)及び式(IIc)中のＲ³、並びに式(IIb)及び式(IIc)中のＲ⁴は、それぞれ独立して水素、一価の飽和脂肪族炭化水素基、一価の芳香族炭化水素基、又は一価の複素環基である］で表される官能基、下記式(IIIa)：
−Ｃ≡Ｎ→Ｏ ・・・ (IIIa)
で表される官能基、及び下記式(IVa)又は下記式(IVb)：
Ｒ⁵−Ｃ≡Ｎ→Ｎ− ・・・ (IVa)
−Ｃ≡Ｎ→Ｎ−Ｒ⁶ ・・・ (IVb)
［式(IVa)中のＲ⁵及び式(IVb)中のＲ⁶は、それぞれ独立して、水素、一価の飽和脂肪族炭化水素基、一価の芳香族炭化水素基、又は一価の複素環基である］で表される官能基が好ましい。ここで、Ｘ及びＹは、同一でも、異なってもよい。 In the compound of the above formula (I) to be blended in the rubber composition of the present invention, X and Y include the following formula (IIa), the following formula (IIb) or the following formula (IIc):

[R ² in Formula (IIa) and Formula (IIb), R ³ in Formula (IIa) and Formula (IIc), and R ^{4 in} Formula (IIb) and Formula (IIc) are each independently hydrogen A monovalent saturated aliphatic hydrocarbon group, a monovalent aromatic hydrocarbon group, or a monovalent heterocyclic group], a functional group represented by the following formula (IIIa):
-C≡N → O (IIIa)
And the following formula (IVa) or the following formula (IVb):
R ⁵ -C≡N → N- (IVa)
-C≡N → N-R ⁶ ... (IVb)
[R ⁵ in Formula (IVa) and R ⁶ in Formula (IVb) are each independently hydrogen, a monovalent saturated aliphatic hydrocarbon group, a monovalent aromatic hydrocarbon group, or a monovalent Is a heterocyclic group]. Here, X and Y may be the same or different.

  In a preferred example of the rubber composition of the present invention, the reinforcing filler is carbon black.

  In the rubber composition of the present invention, the compounding amount of the compound represented by the formula (I) is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber component, and 0.2 to 5 parts by mass. More preferably it is. In this case, the effect of the compound of formula (I) as a crosslinking agent is sufficiently exhibited, and the elastic modulus after vulcanization of the rubber composition does not become too high.

  In the tire of the present invention, the rubber composition is applied to at least one of the tire members.

  According to the present invention, by adding a reinforcing filler and a compound having two nitrogen-containing 1,3-dipoles in a specific ratio to the rubber component, the scorch stability and vulcanization resistance are improved. A rubber composition excellent in returnability and heat generation durability can be provided.

  The present invention is described in detail below. The rubber composition of the present invention comprises 20 to 150 parts by mass of a reinforcing filler and a compound represented by the above formula (I) with respect to 100 parts by mass of a rubber component composed of at least one of natural rubber and synthetic rubber. It mix | blends 0.01-30 mass parts, It is characterized by the above-mentioned. The compound of the formula (I) compounded in the rubber composition of the present invention has two nitrogen-containing 1,3-dipoles, and the nitrogen-containing 1,3-dipole part reacts with the rubber component. It functions as a crosslinking agent and can improve the scorch stability, vulcanization resistance and heat generation durability of the rubber composition.

  The rubber component used in the rubber composition of the present invention is selected from natural rubber and synthetic rubber. The rubber component includes natural rubber (NR), polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), acrylonitrile-butadiene copolymer rubber (NBR), and butyl rubber. Examples include vulcanizable synthetic rubbers such as (IIR), halogenated butyl rubber, brominated paramethylstyrene isobutylene copolymer, ethylene-propylene-terpolymer, and polychloroprene rubber (CR). These rubber components may be used alone or in a blend of two or more.

  The rubber composition of the present invention contains 0.01 to 30 parts by weight, preferably 0.1 to 10 parts by weight, preferably 0.2 to 5 parts by weight of the compound represented by the formula (I) with respect to 100 parts by weight of the rubber component. More preferably, it is contained in parts by mass. When the compounding amount of the compound of the formula (I) is less than 0.01 parts by mass with respect to 100 parts by mass of the rubber component, there is no effect as a crosslinking agent, and the object of the present invention cannot be achieved. Even if the compound of formula (I) is added in an amount exceeding 30 parts by mass with respect to 100 parts by mass of the rubber component, the effect as a crosslinking agent is saturated, while the elastic modulus after vulcanization of the rubber composition is high. Demerits such as excessively reduced and reduced elongation at the time of cutting appear.

In the above formula (I), R ¹ is a divalent saturated aliphatic hydrocarbon group, a divalent aromatic hydrocarbon group, or a divalent heterocyclic group. Here, the divalent saturated aliphatic hydrocarbon group includes methylene group, ethylene group, trimethylene group, tetramethylene group, hexamethylene group, octamethylene group, decamethylene group, dodecamethylene group, propylene group, 2-methyltrimethyl group. Examples thereof include linear or branched alkylene groups such as a methylene group and 2-ethylhexamethylene group. Examples of the divalent aromatic hydrocarbon group include a phenylene group, a tolylene group, a dimethylphenylene group, a xylylene group, and a naphthylene group. Examples of the divalent heterocyclic group include a pyridinediyl group, a thiophenediyl group, A quinoline diyl group etc. are mentioned. Among these, R ¹ of formula (I), a divalent saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms, a phenylene group and a naphthylene group.

［式中、Ｒ²、Ｒ³及びＲ⁴は、上記と同義である］で表されるニトロンからＲ²、Ｒ³及びＲ⁴の何れか一つを除いた構造の官能基であり、上記式(IIIa)で表される官能基は、下記式(III)：
Ｒ−Ｃ≡Ｎ→Ｏ ・・・ (III)
［式中、Ｒは、一価の基である］で表されるニトリルオキシドからＲを除いた構造の官能基であり、上記式(IVa)又は上記式(IVb)で表される官能基は、下記式(IV)：
Ｒ⁵−Ｃ≡Ｎ→Ｎ−Ｒ⁶ ・・・ (IV)
［式中、Ｒ⁵及びＲ⁶は、上記と同義である］で表されるニトリルイミンからＲ⁵及びＲ⁶の何れか一つを除いた構造の官能基である。従って、上記式(IIa)、上記式(IIb)又は上記式(IIc)で表される官能基を有する式(I)の化合物はニトロンの一種であり、上記式(IIIa)で表される官能基を有する式(I)の化合物はニトリルオキシドの一種であり、上記式(IVa)又は上記式(IVb)で表される官能基を有する式(I)の化合物はニトリルイミンの一種である。 X and Y in the above formula (I) are monovalent functional groups having a nitrogen-containing 1,3-dipole, and X and Y may be the same or different. Here, as the monovalent functional group having a nitrogen-containing 1,3-dipole, the functional group represented by the above formula (IIa), the above formula (IIb) or the above formula (IIc), or the above formula (IIIa) And a functional group represented by the above formula (IVa) or the above formula (IVb) are preferable. The functional group represented by the above formula (IIa), the above formula (IIb) or the above formula (IIc) has the following formula (II):

[Wherein R ² , R ^3, and R ⁴ have the same meaning as described above] are functional groups having a structure obtained by removing any one of R ² , R ^3, and R ⁴ from the nitrone represented by The functional group represented by the formula (IIIa) has the following formula (III):
R-C≡N → O (III)
[Wherein R is a monovalent group] is a functional group having a structure in which R is removed from the nitrile oxide, and the functional group represented by the above formula (IVa) or (IVb) is The following formula (IV):
R ⁵ —C≡N → N—R ⁶ (IV)
[Wherein R ⁵ and R ⁶ are as defined above], and a functional group having a structure obtained by removing any one of R ⁵ and R ^{6 from} a nitrileimine. Accordingly, the compound of the formula (I) having a functional group represented by the above formula (IIa), the above formula (IIb) or the above formula (IIc) is a kind of nitrone, and the functional group represented by the above formula (IIIa). The compound of the formula (I) having a group is a kind of nitrile oxide, and the compound of the formula (I) having a functional group represented by the above formula (IVa) or (IVb) is a kind of nitrile imine.

In the above formula (IIa), the above formula (IIb) and the above formula (IIc), R ² , R ³ and R ⁴ are each independently hydrogen, a monovalent saturated aliphatic hydrocarbon group, or a monovalent aromatic. It is a hydrocarbon group or a monovalent heterocyclic group. Here, the monovalent saturated aliphatic hydrocarbon group may be a linear or branched alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, an isobutyl group, a hexyl group, an octyl group, or a 2-ethylhexyl group. Etc. Examples of the monovalent aromatic hydrocarbon group include a phenyl group, tolyl group, benzyl group, xylyl group, and naphthyl group. Examples of the monovalent heterocyclic group include a pyridyl group, a thienyl group, and a quinolyl group. Is mentioned.

In the above formula (IVa) and (IVb), R ⁵ and R ⁶ are each independently hydrogen, a monovalent saturated aliphatic hydrocarbon group, a monovalent aromatic hydrocarbon group, or one It is a valent heterocyclic group. Here, examples of the monovalent saturated aliphatic hydrocarbon group, the monovalent aromatic hydrocarbon group, and the monovalent heterocyclic group include R ² in the formula (IIa), the formula (IIb), and the formula (IIc), the group exemplified as R ³ and R ⁴ can be exemplified similarly.

  The production method of the compound of the formula (I) is not particularly limited. For example, the compound of the formula (I) having a functional group represented by the formula (IIa), the formula (IIb) or the formula (IIc) ( Nitron) can be synthesized by dehydration condensation of dialdehydes and substituted hydroxyamines.

  The rubber composition of the present invention contains 20 to 150 parts by mass of a reinforcing filler with respect to 100 parts by mass of the rubber component. If the compounding amount of the reinforcing filler is less than 20 parts by mass relative to 100 parts by mass of the rubber component, the rigidity after vulcanization of the rubber composition is insufficient, and mechanical properties such as fracture characteristics and wear resistance are reduced. On the other hand, when it exceeds 150 parts by mass, workability during kneading of the rubber composition is deteriorated. Here, examples of the reinforcing filler used in the rubber composition of the present invention include carbon black and silica. Among these, carbon black is preferable. Examples of the carbon black include GPF, FEF, SRF, HAF, ISAF, and SAF grades. On the other hand, examples of the silica include wet silica and dry silica. These reinforcing fillers may be used alone or in combination of two or more.

  Furthermore, the rubber composition of the present invention preferably contains 0.1 to 10 parts by mass of sulfur, more preferably 0.2 to 5 parts by mass with respect to 100 parts by mass of the rubber component. By using the compound represented by the above formula (I) and sulfur together, a vulcanized rubber having excellent scorch stability, anti-vulcanization resistance and heat generation durability can be obtained. Here, if the compounding amount of sulfur is less than 0.1 part by mass with respect to 100 parts by mass of the rubber component, a sufficient crosslinking density as a vulcanized rubber may not be formed, and if it exceeds 10 parts by mass, the vulcanization of the rubber composition may occur. Demerits such as the later elasticity becoming too high and the elongation at the time of cutting being lowered may appear.

  In the rubber composition of the present invention, in addition to the rubber component, the compound of formula (I), the reinforcing filler, sulfur, a compounding agent usually used in the rubber industry, such as a vulcanization activator, a vulcanization accelerator. Agents, softeners, plasticizers, anti-aging agents, processability improvers, tackifiers and the like can be appropriately blended depending on the purpose. As these compounding agents, commercially available products can be suitably used. The rubber composition is prepared by, for example, blending various compounding agents appropriately selected as necessary together with the compound of the formula (I) and the reinforcing filler in the rubber component, kneading, heating, extrusion. It can manufacture by doing.

  The kneading conditions are not particularly limited, and various conditions such as the input volume to the kneading apparatus, the rotational speed of the rotor, the ram pressure, the kneading temperature, the kneading time, the type of the kneading apparatus, and the like depending on the purpose. Can be selected as appropriate. Moreover, as a kneading apparatus, the Banbury mixer, intermix, kneader etc. which are normally used for kneading | mixing of a rubber composition are mentioned, for example.

  There is no restriction | limiting in particular as said heating conditions, It can select suitably according to the objective about various conditions, such as heating temperature, heating time, and a heating apparatus. Moreover, as a heating apparatus, the roll machine etc. which are normally used for the heating of a rubber composition are mentioned, for example.

  The conditions for the extrusion are not particularly limited, and various conditions such as an extrusion time, an extrusion speed, an extrusion apparatus, and an extrusion temperature can be appropriately selected according to the purpose. Moreover, as an extrusion apparatus, the extruder etc. which are normally used for extrusion of the rubber composition for tires are mentioned, for example. In addition, extrusion temperature can be suitably determined according to the objective.

  The rubber composition of the present invention is molded into the desired product shape and then vulcanized to obtain a product. There are no particular restrictions on the equipment, system, conditions, etc. for vulcanization. Can be appropriately selected according to the purpose. As an apparatus for performing vulcanization, for example, a molding vulcanizer using a mold usually used for vulcanization of a rubber composition for tires can be cited. The temperature during vulcanization is usually about 100 to 190 ° C.

  The tire of the present invention is characterized in that the above rubber composition is applied to at least one of the tire members. Here, examples of the tire member include tread rubber, side rubber, and bead filler. The tire of the present invention has a conventionally known structure and is not particularly limited, and can be produced by an ordinary method. Moreover, as gas with which the tire of the present invention is filled, an inert gas such as nitrogen, argon, helium, etc. can be used in addition to normal or air with adjusted oxygen partial pressure.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

で表される目的のＮ,Ｎ'-ジフェニル-ｐ-フェニレンジニトロン（淡黄色結晶）を得た。なお、生成物の収量は6.06g（19.2mmol）であり、収率は62％であった。 (Synthesis Example 1: Synthesis of N, N′-diphenyl-p-phenylenedinitrone)
To a 300 mL Erlenmeyer flask, 100 mL ethanol, 6.75 g (61.8 mmol) N-phenylhydroxylamine, and 4.15 g (30.9 mmol) terephthalaldehyde were added and boiled gently for 20 minutes. The solution was then concentrated to a volume of 30 mL, and deionized water (about 20 mL) was added in portions until the solution became cloudy. The solution was heated again until it became transparent, and then cooled overnight in a refrigerator (5 ° C.). Thereafter, the precipitated crystals are filtered off, washed with 100 mL of deionized water, and dried under reduced pressure to obtain the following formula (V):

The target N, N′-diphenyl-p-phenylenedinitrone represented by the formula (light yellow crystal) was obtained. The product yield was 6.06 g (19.2 mmol), and the yield was 62%.

で表される目的のＮ,Ｎ'-ジメチル-ｐ-フェニレンジニトロン（白色結晶）を得た。なお、生成物の収量は2.44g（12.7mmol）であり、収率は41％であった。 (Synthesis Example 2: Synthesis of N, N′-dimethyl-p-phenylenedinitrone)
To a 300 mL Erlenmeyer flask, 100 mL ethanol, 5.16 g (61.8 mmol) N-methylhydroxylamine hydrochloride, 2.5 g (62.5 mmol) sodium hydroxide, and 4.15 g (30.9 mmol) terephthalaldehyde were added sequentially. Boil gently for 20 minutes. The solution was then concentrated to a volume of 25 mL and deionized water (about 20 mL) was added in portions until the solution became cloudy. The solution was heated again until it became transparent, and then cooled overnight in a refrigerator (5 ° C.). Thereafter, the precipitated crystals are separated by filtration, washed with 100 mL of deionized water, and dried under reduced pressure to obtain the following formula (VI):

The target N, N′-dimethyl-p-phenylenedinitrone represented by the formula (white crystals) was obtained. The product yield was 2.44 g (12.7 mmol), and the yield was 41%.

<Evaluation of physical properties of rubber composition>
According to the formulation shown in Table 1, each rubber composition was prepared using a Banbury mixer, and the tensile properties and heat fatigue time of the obtained rubber composition were measured by the following methods. The results are shown in Table 1.

(1) Tensile properties Each rubber composition was vulcanized at 145 ° C for 45 minutes, and then subjected to a tensile test in accordance with JIS K 6251. Elongation at break (EB), Tensile strength (TB), 300% elongation Tensile stress was measured, and the value of the rubber composition of the comparative example was taken as 100, and each was expressed as an index.

(2) Heat fatigue time After each rubber composition was vulcanized at 145 ° C. for 45 minutes, a constant stress measurement was performed with a flexometer described in JIS K6265, and the time until a crack occurred inside the sample was determined as the heat fatigue time. And the index was displayed with the comparative example as 100. The larger the index value, the longer the heat fatigue time and the better the heat resistance.

* 1 Made by Asahi Kasei Co., Ltd., Toughden 4350, Bonded styrene content = 39% by mass, Vinyl bond = 38%, Oil-extended with 50 parts by mass of aromatic oil per 100 parts by mass of rubber component.
* 2 Antigen 6C, N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, manufactured by Sumitomo Chemical.
* 3 Ouchi Shinsei Chemical Industries, Noxeller CZ, N-cyclohexyl-2-benzothiazolesulfenamide.
* 4 Ouchi Shinsei Chemical Industry, Noxeller TOT-N, Tetrakis (2-ethylhexyl) thiuram disulfide.

  From the comparison between the comparative example of Table 1 and the examples, by blending the rubber composition with a compound having two nitrogen-containing 1,3-dipole parts, while sufficiently ensuring the fracture characteristics of the rubber composition, It can be seen that the heat resistance of the rubber composition can be greatly improved.

Claims (8)

For 100 parts by mass of a rubber component made of at least one of natural rubber and synthetic rubber, 20 to 150 parts by mass of a reinforcing filler, and the following formula (I):
X-R ¹ -Y (I)
[Wherein, R ¹ is a divalent saturated aliphatic hydrocarbon group, a divalent aromatic hydrocarbon group, or a divalent heterocyclic group, and X and Y are each independently nitrogen-containing 1, A rubber composition comprising 0.01 to 30 parts by mass of a compound represented by the formula: a monovalent functional group having a 3-dipole]. 2. The rubber composition according to claim 1, wherein R ^{1 in the} formula (I) is a C 1-12 divalent saturated aliphatic hydrocarbon group, phenylene group or naphthylene group. The monovalent functional group having a nitrogen-containing 1,3-dipole as X in the formula (I) is represented by the following formula (IIa), the following formula (IIb) or the following formula (IIc):

[R ² in Formula (IIa) and Formula (IIb), R ³ in Formula (IIa) and Formula (IIc), and R ^{4 in} Formula (IIb) and Formula (IIc) are each independently hydrogen A monovalent saturated aliphatic hydrocarbon group, a monovalent aromatic hydrocarbon group, or a monovalent heterocyclic group], a functional group represented by the following formula (IIIa):
-C≡N → O (IIIa)
And the following formula (IVa) or the following formula (IVb):
R ⁵ -C≡N → N- (IVa)
-C≡N → N-R ⁶ ... (IVb)
[R ⁵ in formula (IVa) and R ⁶ in formula (IVb) are each independently hydrogen, a monovalent saturated aliphatic hydrocarbon group, a monovalent aromatic hydrocarbon group, or a monovalent The rubber composition according to claim 1, wherein the rubber composition is any one of functional groups represented by   A monovalent functional group having a nitrogen-containing 1,3-dipole as Y in the formula (I) is a functional group represented by the formula (IIa), the formula (IIb) or the formula (IIc); The rubber composition according to claim 1, wherein the rubber composition is any one of the functional group represented by the formula (IIIa) and the functional group represented by the formula (IVa) or the formula (IVb).   The rubber composition according to claim 1, wherein the reinforcing filler is carbon black.   The rubber composition according to claim 1, wherein the compounding amount of the compound represented by the formula (I) is 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber component.   The rubber composition according to claim 6, wherein the compounding amount of the compound represented by the formula (I) is 0.2 to 5 parts by mass with respect to 100 parts by mass of the rubber component.   A tire comprising the rubber composition according to claim 1 applied to at least one of tire members.