JP5567400B2 - Rubber composition for tire, method for producing the same, and tire for heavy load - Google Patents

Description

The present invention relates to a tire rubber composition, a method for producing the same, and a heavy duty tire using the rubber composition.

Conventionally, the fuel consumption of a vehicle has been reduced by reducing tire rolling resistance and suppressing heat generation. In recent years, there has been an increasing demand for lower fuel consumption of vehicles by using tires, and not only passenger tires but also heavy duty tires for trucks and buses are required to have lower fuel consumption.

For improving fuel efficiency (also referred to as low heat generation) in heavy-duty tires, techniques such as carbon black having a high structure and surface activation are mainly used. In recent years, as a method for further improving fuel economy, a technique of replacing carbon black with silica has been tried. However, since silica has lower reinforcement than carbon black, when the above substitution is performed, the fracture characteristics (rubber strength) and wear resistance tend to deteriorate. Therefore, in heavy duty tires used for trucks, buses and the like, which are much heavier than passenger cars, it has been difficult to improve fuel efficiency using silica.

In addition, natural rubber, which is widely used in tire rubber compositions, has a higher Mooney viscosity and lower processability than other synthetic rubbers. It is used after lowering. Therefore, when natural rubber is used, such a process is required, so that productivity is lowered. Further, since the molecular chain of natural rubber is cut by mastication, there is a problem that the properties (for example, high wear resistance, low fuel consumption, rubber strength) of the high molecular weight polymer inherent to natural rubber are lost. It was.

Patent Documents 1 to 4 propose to reduce rolling resistance using modified diene rubbers such as modified butadiene rubber and modified styrene butadiene rubber. Patent Documents 5 and 6 propose improving rubber strength by using natural rubber subjected to protein removal treatment. However, there is still room for improvement in terms of improving the fuel efficiency, wear resistance, fracture characteristics and workability in a well-balanced manner.

JP 2001-114939 A JP 2005-126604 A JP 2005-325206 A JP 2000-344955 A JP-A-8-12814 Japanese Patent Laid-Open No. 11-12306

The present invention solves the above-mentioned problems and provides a tire rubber composition that can improve fuel economy, wear resistance, fracture characteristics and processability in a well-balanced manner, a method for producing the same, and a heavy duty tire produced using the rubber composition. The purpose is to provide.

The present invention contains a rubber component comprising a polar group-containing copolymer obtained by copolymerizing a conjugated diene compound and a polar group-containing vinyl compound, and a modified natural rubber having a phosphorus content of 200 ppm or less, and the above polar The group-containing vinyl compound has a polymerizable unsaturated bond and a polar group, and any carbon atom that forms the polymerizable unsaturated bond and at least one carbon atom to which the polar group is bonded. The present invention relates to a rubber composition for tires, which is a compound bonded through atoms, and has a cis content of a double bond portion of the conjugated diene compound of 80 mol% or more.

The polar group is preferably a group represented by a hydroxyl group, —NR ₂ , or —Si (OR) _k (R) _3-k .
(However, R represents hydrogen or a C1-C8 hydrocarbon group, which may be the same or different. K represents an integer of 1, 2 or 3.)

（式（Ｉ）中、Ｒ^１は、水素、ビニル基又は炭素数１〜３の脂肪族炭化水素基を表し、同一であっても異なっていてもよい。Ｒ^２は、水素又は炭素数１〜３の脂肪族炭化水素基を表し、同一であっても異なっていてもよい。Ｒ^３は、水素、又は炭素数１〜８の脂肪族若しくは脂環族炭化水素基を表す。Ｘは、水酸基、前記−ＮＲ_２、又は前記−Ｓｉ（ＯＲ）_ｋ（Ｒ）_３−ｋで表される基を表す。ｎは、１〜１０の整数を表す。前記Ｒ^１、Ｒ^２、Ｒ^３、該Ｒ^２が結合する炭素原子、該Ｒ^３が結合する炭素原子は、それぞれ互いに結合して環構造を形成してもよい。）
で表される化合物であることが好ましい。 The polar group-containing vinyl compound has the following general formula (I):

(In Formula (I), R ¹ represents hydrogen, a vinyl group, or an aliphatic hydrocarbon group having 1 to 3 carbon atoms, and may be the same or different. R ² represents hydrogen or one carbon atom. Represents an aliphatic hydrocarbon group having ˜3, which may be the same or different, R ³ represents hydrogen or an aliphatic or alicyclic hydrocarbon group having 1 to 8 carbon atoms, X is Represents a group represented by a hydroxyl group, the —NR ₂ , or the —Si (OR) _k (R) _{3 —k} , and n represents an integer of ^{1 to} 10. The R ¹ , R ² , R ³ , The carbon atom to which R ² is bonded and the carbon atom to which R ³ is bonded may be bonded to each other to form a ring structure.)
It is preferable that it is a compound represented by these.

The polar group-containing copolymer has a weight average molecular weight of 1.0 × 10 ^{3 to} 2.0 × 10 ⁶ and a content of the polar group-containing vinyl compound of 0.03 to 40% by mass. Is preferred.

The conjugated diene compound is preferably 1,3-butadiene and / or isoprene.

Before the polar group-containing copolymer is copolymerized, the polar group-containing vinyl compound and the following general formula (II);
M (R ⁴ ) _m (II)
(In formula (II), M represents aluminum, boron, silicon, or titanium. R ⁴ represents an aliphatic or alicyclic hydrocarbon group having 1 to 8 carbon atoms, an aliphatic or aliphatic group having 1 to 8 carbon atoms. A cyclic alkoxy group or halogens, which may be the same or different, m represents an integer of 3 or 4)
It is preferable that it is obtained by making it react with the compound represented by these, and then copolymerizing the obtained reaction product and the said conjugated diene compound.

The nitrogen content in the modified natural rubber is preferably 0.3% by mass or less.

The gel content measured as the toluene insoluble content of the modified natural rubber is preferably 20% by mass or less.

The modified natural rubber is preferably obtained by saponifying natural rubber latex.

In the rubber composition, the content of the polar group-containing copolymer is 5 to 60% by mass, and the total content of the modified natural rubber is 40 to 95% by mass in 100% by mass of all rubber components. It is preferable.

The rubber composition preferably contains 5 to 150 parts by mass of carbon black with respect to 100 parts by mass of all rubber components.

The rubber composition is preferably used for a tread of a heavy duty tire.

The present invention also relates to a method for producing the rubber composition which does not include a step of masticating natural rubber.

The present invention also relates to a heavy duty tire produced using the rubber composition.

According to the present invention, a polar group-containing copolymer having a high cis content obtained by copolymerizing a specific polar group-containing vinyl compound together with a conjugated diene compound, and a modified natural rubber having a phosphorus content of 200 ppm or less ( (Hereinafter, also referred to as HPNR), and therefore, by using the rubber composition in a tread of a heavy duty tire, a heavy load having improved fuel economy, wear resistance and fracture characteristics in a well-balanced manner. Heavy duty tires can be provided. The rubber composition also has excellent processability that does not require a mastication step.

The rubber composition for tires of the present invention comprises a polar group-containing copolymer obtained by copolymerizing a specific polar group-containing vinyl compound together with a conjugated diene compound, a modified natural rubber having a phosphorus content of 200 ppm or less ( HPNR). HPNR in which phospholipids contained in natural rubber (NR) have been reduced and removed (preferably HPNR from which proteins and gels have also been removed) has the property of not generating heat, and the incorporation of fillers such as carbon black is fast, Since the dispersibility of the filler can be improved, fuel consumption can be further reduced as compared with the use of NR.

However, a rubber composition using HPNR alone as a rubber component tends to be unable to ensure sufficient wear resistance when used in a heavy duty tire. Although the wear resistance can be improved to some extent by using butadiene rubber, the effect is not sufficient.

On the other hand, in the present invention, a high cis content polar group-containing copolymer obtained by copolymerizing a specific polar group-containing vinyl compound with a conjugated diene compound is used as a rubber component together with HPNR. Good abrasion resistance and fracture characteristics can be obtained, and fuel consumption can be further reduced.

In addition, the unvulcanized rubber composition containing HPNR is excellent in productivity because good processability is obtained in a kneading step with a component such as a filler without performing a kneading step in advance. ing.

The polar group-containing copolymer is obtained by copolymerizing a conjugated diene compound and a polar group-containing vinyl compound. Further, the polar group-containing vinyl compound has a polymerizable unsaturated bond and a polar group, and any carbon atom forming the polymerizable unsaturated bond and at least the carbon atom to which the polar group is bonded. It is a compound that binds through one carbon atom. That is, in the case where the polar group-containing vinyl compound is represented by the following formula (I), two carbon atoms having a double bond (polymerizable unsaturated bond) and X (polar group) and forming a double bond are used. The carbon atom to which R ¹ and C are bonded and the carbon atom to which X is bonded are bonded through n C (at least one carbon atom) in “— (C (R ² ) ₂ ) _n —”. doing. Furthermore, in the polar group-containing copolymer, the cis content of the double bond portion of the conjugated diene compound is 80 mol% or more.

The number of polymerizable unsaturated bonds and polar groups in the polar group-containing vinyl compound may be one each, or two or more.

Although it does not specifically limit as a polymerizable unsaturated bond, A polymerizable double bond is suitable. It does not specifically limit as a polar group, For example, -NR < ₂ > (R represents hydrogen or a C1-C8 hydrocarbon group, and may be same or different. For example, an amino group, a monoalkyl, Amino group, dialkylamino group), imino group, nitrile group, ammonium group, imide group, amide group, hydrazo group, azo group, diazo group, hydroxyl group, carboxyl group, carbonyl group, oxycarbonyl group, sulfide group, sulfonyl group, A thiocarbonyl group, a group represented by —Si (OR) _k (R) _{3 —k} (R represents hydrogen or a hydrocarbon group having 1 to 8 carbon atoms, and may be the same or different. k represents an integer of 1, 2 or 3.) Among them, a group represented by hydroxyl group (—OH), —NR ₂ , —Si (OR) _k (R) _3-k (Trialkoxysilyl group Are preferred. In this case, all the performances of wear resistance, low heat build-up, fracture characteristics, and workability can be obtained with a good balance.

In the group represented by —NR ₂ , —Si (OR) _k (R) _3-k , the hydrocarbon group having 1 to 8 carbon atoms in R is not particularly limited, and includes a methyl group, an ethyl group, and n-propyl. Group, isopropyl group, n-butyl group, iso-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group and other alkyl groups. Specific examples of the group represented by —Si (OR) _k (R) _3-k include, for example, a trimethoxysilyl group, a triethoxysilyl group, a triisopropoxysilyl group, a methyldimethoxysilyl group, and a methyldiethoxysilyl group. Group, dimethylethoxysilyl group and the like.

（式（Ｉ）中、Ｒ^１は、水素、ビニル基又は炭素数１〜３の脂肪族炭化水素基を表し、同一であっても異なっていてもよい。Ｒ^２は、水素又は炭素数１〜３の脂肪族炭化水素基を表し、同一であっても異なっていてもよい。Ｒ^３は、水素、又は炭素数１〜８の脂肪族若しくは脂環族炭化水素基を表す。Ｘは、水酸基、上記−ＮＲ_２、又は上記−Ｓｉ（ＯＲ）_ｋ（Ｒ）_３−ｋで表される基を表す。ｎは、１〜１０の整数を表す。上記Ｒ^１、Ｒ^２、Ｒ^３、該Ｒ^２が結合する炭素原子、該Ｒ^３が結合する炭素原子は、それぞれ互いに結合して環構造を形成してもよい。）

（式（Ｉ−１）、（Ｉ−２）中、Ｒ^１、Ｒ^２、Ｒ^３、Ｘ、ｎは、前記と同様である。）
なお、式（Ｉ−１）、（Ｉ−２）においても、式（Ｉ）と同様、環構造を形成してもよい。 As the polar group-containing vinyl compound, for example, a compound represented by the following formula (I) is preferable, and a compound represented by the following general formula (I-1) and / or (I-2) is particularly preferable. Can be used for Since these compounds have a structure in which a polar group is bonded to a carbon atom forming a double bond via at least one carbon, when the compound and a conjugated diene compound are copolymerized, The polymerization reaction is difficult to be inhibited. In addition, the polar group-containing copolymer obtained by copolymerizing these compounds with a conjugated diene compound has a large interaction with the filler, and the filler is easily dispersed during kneading. All the properties of fracture characteristics and workability can be obtained in a well-balanced manner.

(In Formula (I), R ¹ represents hydrogen, a vinyl group, or an aliphatic hydrocarbon group having 1 to 3 carbon atoms, and may be the same or different. R ² represents hydrogen or one carbon atom. Represents an aliphatic hydrocarbon group having ˜3, which may be the same or different, R ³ represents hydrogen or an aliphatic or alicyclic hydrocarbon group having 1 to 8 carbon atoms, X is Represents a hydroxyl group, a group represented by —NR ₂ or the above —Si (OR) _k (R) _{3 —k} , n represents an integer of 1 to 10. The above R ¹ , R ² , R ³ , The carbon atom to which R ² is bonded and the carbon atom to which R ³ is bonded may be bonded to each other to form a ring structure.)

(In formulas (I-1) and (I-2), R ¹ , R ² , R ³ , X, and n are the same as described above.)
In formulas (I-1) and (I-2), a ring structure may be formed as in formula (I).

In the polar group-containing vinyl compound represented by the formula (I), R ¹ is preferably hydrogen, a vinyl group or an aliphatic hydrocarbon group having 1 to 2 carbon atoms, and R ² is hydrogen from the viewpoint of ease of copolymerization. Or a C1-C2 aliphatic hydrocarbon group is preferable. R ³ is preferably hydrogen, an aliphatic or alicyclic hydrocarbon group having 1 to 4 carbon atoms from the viewpoint of good wear resistance, low heat build-up, fracture characteristics, and workability. Examples of the aliphatic hydrocarbon group for R ¹ and R ² include alkyl groups such as a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. Examples of the aliphatic hydrocarbon group for R ³ include an n-butyl group, an iso-butyl group, a sec-butyl group, a tert-butyl group, and a pentyl group, in addition to the aliphatic hydrocarbon groups listed for R ¹ and R ^2. Hexyl group, heptyl group, 2-ethylhexyl group, octyl group and the like. Examples of the alicyclic hydrocarbon group represented by R ³ include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cyclopentenyl group, and a cyclohexenyl group. R ³ may have a substituent.

From the viewpoint of ease of copolymerization, n is preferably 2 to 10, and more preferably 4 to 10. If n exceeds 10, the cost tends to increase. Incidentally, when n is an integer of 2 or more, the compounds of formula (I), - (C (R 2) 2) - may have been a unit having two or more represented, R in the same unit ² and R ² of different units may be the same group or different groups.

Examples of the polar group-containing vinyl compound represented by the formula (I) include 3-buten-1-ol, 3-methyl-3-buten-1-ol, 3-methylidene-hexane-1-ol, 5- Hexen-1-ol, 2-methyl-5-hexen-1-ol, 4-methylidenehexane-2-ol, 4-penten-1-ol, 4-methyl-4-penten-1-ol, 4- Methylidenehexane-1-ol, 5-methyl-5-hexen-1-ol, 5-methylideneheptan-1-ol, 5-hexen-4-methyl-1-ol, 4,5-dimethyl-5 Hexen-1-ol, 4-methyl-5-methylideneheptan-1-ol, 3,4-dimethyl-5-hexen-1-ol, 3,4,5-trimethyl-5-hexen-1-ol, 3,4-dimension Ru-5-methylideneheptan-1-ol, 2-ethyl-5-methyl-5-hexen-1-ol, 3-hydroxy-6-methyl-7-octene, 6-hepten-1-ol, 6- Methyl-6-hepten-1-ol, 6-methylideneoctane-1-ol, 7-octen-1-ol, 7-methyl-7-octen-1-ol, 7-methylidenonan-1-ol, 8- Nonen-1-ol, 8-methyl-8-nonen-1-ol, 8-methylidenedecan-1-ol, 9-decen-1-ol, 9-methyl-9-decen-1-ol, 9-methylidene Undecan-1-ol, 10-undecen-1-ol, 10-methyl-10-undecen-1-ol, 10-methylidenedecan-1-ol, 7,9,10-trimethyl-10 Undecen-1-ol, 2-cyclohexyl-5-hexen-1-ol, 3-cyclohexyl-6-hepten-2-ol, 4-hexen-1-ol, 5-hepten-1-ol, 6-octene- 1-ol, 7-nonen-1-ol, 8-decene-1-ol, 4-methyl-5-hepten-2-ol, 5-methyl-6-octen-2-ol, 6-methyl-7- Nonen-2-ol, 3-methyl-4-hexen-1-ol, 4-methyl-5-hepten-1-ol, 5-methyl-6-octen-1-ol, 6-methyl-7-nonen 1-ol, 7-methyl-8-decen-1-ol, 3-methyl-4-hepten-1-ol, 4-methyl-5-octen-1-ol, 5-methyl-6-nonen-1- All, 4-heptene- 1-ol, 5-octen-1-ol, 6-nonen-1-ol, 5,6-dimethyl-5-hepten-1-ol, (Z) -5-methyl-5-hepten-1-ol, (E) -7-methyl-7-nonen-2-ol and the like. Among these, 3-methyl-3-buten-1-ol, 4-penten-1-ol, 5-hexen-1-ol, 6 and the like are obtained from the viewpoint of easy availability, ease of copolymerization or performance improvement. -Hepten-1-ol, 9-decen-1-ol, 10-undecen-1-ol, 4-hexen-1-ol, 4-hepten-1-ol and 5-octen-1-ol are preferred.

Also included are compounds in which the hydroxyl groups of the hydroxyl group-containing vinyl compounds listed above are substituted with —NH ₂ , for example, 1-amino-3-butene, 1-amino-3-methyl-3-butene, 1-amino- (3-methylidene) hexane, 2-amino-4-hexene, 2-amino-4-methyl-4-hexene, 2-amino- (4-methylidene) hexane, 1-amino-4-pentene, 1-amino- 4-methyl-4-penten-1-ol, 1-amino- (4-methylidene) hexane, 1-amino-5-methyl-5-hexene, 1-amino- (5-methylidene) heptane, 1-amino -4-methyl-5-hexene, 1-amino-4,5-dimethyl-5-hexene, 1-amino-4-methyl- (5-methylidene) heptane, 1-amino-3,4-dimethyl-5 -Heki Sene, 1-amino-3,4,5-trimethyl-5-hexene, 1-amino-3,4-dimethyl- (5-methylidene) heptane, 1-amino-2-ethyl-5-methyl-5- Hexene, 3-amino-6-methyl-7-octene, 1-amino-6-heptene, 1-amino-6-methyl-6-heptene, 1-amino- (6-methylidene) octane, 1-amino-7 -Octene, 1-amino-7-methyl-7-octene, 1-amino- (7-methylidene) nonane, 1-amino-8-nonene, 1-amino-8-methyl-8-nonene, 1-amino- (8-methylidene) decane, 1-amino-9-decene, 1-amino-9-methyl-9-decene, 1-amino- (9-methylidene) undecane, 1-amino-10-undecene, 1-amino- 10-methyl-1 -Undecene, 1-amino-10-methylidenedecane, 1-amino-7,9,10-trimethyl-10-undecene, 1-amino-2-cyclohexyl-5-hexene, 2-amino-3-cyclohexyl-6 -Heptene, 1-amino-4-hexene, 1-amino-5-heptene, 1-amino-6-octene, 1-amino-7-nonene, 1-amino-8-decene, 1-amino-4-methyl -5-heptene, 2-amino-5-methyl-6-octene, 2-amino-6-methyl-7-nonene, 1-amino-3-methyl-4-hexene, 1-amino-4-methyl-5 -Heptene, 1-amino-5-methyl-6-octene, 1-amino-6-methyl-7-nonene, 1-amino-7-methyl-8-decene, 1-amino-3-methyl-4-heptene 1 Amino-4-methyl-5-octene, 1-amino-5-methyl-6-nonene, 1-amino-4-heptene, 1-amino-5-octene, 1-amino-6-nonene and the like.

Further, compounds (1- (N-methylamino) -3-butene, 1- (N-methylamino) -3-methyl-3-butene, wherein the hydroxyl group of the hydroxyl group-containing vinyl compound listed above is substituted with —NHCH _{3. etc.),} - N _(CH 3) compound substituted in the ₂ (1- (N, N- dimethylamino) -3-butene, 1- (N, N- dimethylamino) -3-methyl-3-butene, etc.) Also mentioned.

Moreover, the compound which substituted the hydroxyl group of the hydroxyl group containing vinyl compound enumerated above by the group represented by the said -Si (OR) _k (R) _3-k is also mentioned, for example, 1-triethoxysilyl-3-butene 1-triethoxysilyl-3-methyl-3-butene, 1-triethoxysilyl- (3-methylidene) hexane, 2-triethoxysilyl-4-hexene, 2-triethoxysilyl-4-methyl-4- Hexene, 2-triethoxysilyl- (4-methylidene) hexane, 1-triethoxysilyl-4-pentene, 1-triethoxysilyl-4-methyl-4-penten-1-ol, 1-triethoxysilyl- ( 4-methylidene) hexane, 1-triethoxysilyl-5-methyl-5-hexene, 1-triethoxysilyl- (5-methylidene) heptane, Triethoxysilyl-4-methyl-5-hexene, 1-triethoxysilyl-4,5-dimethyl-5-hexene, 1-triethoxysilyl-4-methyl- (5-methylidene) heptane, 1-triethoxy Silyl-3,4-dimethyl-5-hexene, 1-triethoxysilyl-3,4,5-trimethyl-5-hexene, 1-triethoxysilyl-3,4-dimethyl- (5-methylidene) heptane, 1-triethoxysilyl-2-ethyl-5-methyl-5-hexene, 3-triethoxysilyl-6-methyl-7-octene, 1-triethoxysilyl-6-heptene, 1-triethoxysilyl-6- Methyl-6-heptene, 1-triethoxysilyl- (6-methylidene) octane, 1-triethoxysilyl-7-octene, 1-triethoxysilyl -7-methyl-7-octene, 1-triethoxysilyl- (7-methylidene) nonane, 1-triethoxysilyl-8-nonene, 1-triethoxysilyl-8-methyl-8-nonene, 1-triethoxy Silyl- (8-methylidene) decane, 1-triethoxysilyl-9-decene, 1-triethoxysilyl-9-methyl-9-decene, 1-triethoxysilyl- (9-methylidene) undecane, 1-triethoxy Silyl-10-undecene, 1-triethoxysilyl-10-methyl-10-undecene, 1-triethoxysilyl-10-methylidenedecane, 1-triethoxysilyl-7,9,10-trimethyl-10-undecene, 1-triethoxysilyl-2-cyclohexyl-5-hexene, 2-triethoxysilyl-3-cyclohexyl -6-heptene, 1-triethoxysilyl-4-hexene, 1-triethoxysilyl-5-heptene, 1-triethoxysilyl-6-octene, 1-triethoxysilyl-7-nonene, 1-triethoxysilyl -8-decene, 1-triethoxysilyl-4-methyl-5-heptene, 2-triethoxysilyl-5-methyl-6-octene, 2-triethoxysilyl-6-methyl-7-nonene, 1-tri Ethoxysilyl-3-methyl-4-hexene, 1-triethoxysilyl-4-methyl-5-heptene, 1-triethoxysilyl-5-methyl-6-octene, 1-triethoxysilyl-6-methyl-7 -Nonene, 1-triethoxysilyl-7-methyl-8-decene, 1-triethoxysilyl-3-methyl-4-heptene, 1-triethoxysilyl -4-methyl-5-octene, 1-triethoxysilyl-5-methyl-6-nonene, 1-triethoxysilyl-4-heptene, 1-triethoxysilyl-5-octene, 1-triethoxysilyl-6 -Nonen etc. are mentioned.

Further, compounds (1- (diethoxymethylsilyl) -3-butene, 1- (diethoxymethylsilyl)-(3) in which the triethoxysilyl group of the alkoxysilyl compound listed above is substituted with a diethoxymethylsilyl group. -Methylidene) hexane, etc.), compounds substituted with ethoxydimethylsilyl groups (1- (ethoxydimethylsilyl) -3-methyl-3-butene, 2- (ethoxydimethylsilyl) -4-hexene, etc.), methoxydimethylsilyl groups And compounds substituted with 2-methoxydimethylsilyl-4-methyl-4-hexene, 1-methoxydimethylsilyl-4-pentene, and the like.

In addition to the compounds described above, the polar group-containing vinyl compound represented by the formula (I) includes 2- (1-cyclohexenyl) ethylamine, trimethoxy (7-octen-1-yl) silane, 5- (tri Ethoxysilyl) -2-norbornene can also be suitably used. By using these compounds, the effects of the present invention can be obtained satisfactorily.

The said polar group containing vinyl compound may be used independently and may be used in combination of 2 or more type.

Examples of the conjugated diene compound that can be used in the present invention include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene, 1,3-hexadiene, and the like. Can be mentioned. Among these, 1,3-butadiene and isoprene are preferably used from the viewpoint of practical use such as availability of monomers. A conjugated diene compound may be used independently and may be used in combination of 2 or more type.

The polar group-containing copolymer can be produced by copolymerizing the polar group-containing vinyl compound represented by the formula (I) with the conjugated diene compound. The polymerization method is not particularly limited, and any of solution polymerization method, gas phase polymerization method, and bulk polymerization method can be used. In particular, the solution polymerization method is preferable from the viewpoint of the degree of freedom in polymer design, processability, and the like. .

When the solution polymerization method is used, the monomer concentration in the solvent is preferably 3% by mass or more, and more preferably 5% by mass or more. When the monomer concentration in the solution is less than 3% by mass, the amount of the obtained polymer is small and the cost tends to increase. The monomer concentration in the solvent is preferably 20% by mass or less, and more preferably 15% by mass or less. When the monomer concentration in the solvent exceeds 20% by mass, the solution viscosity becomes too high, stirring becomes difficult, and polymerization tends to be difficult. Moreover, any of a batch type and a continuous type may be sufficient as the superposition | polymerization form.

In the solution polymerization method, the type of catalyst is not particularly limited, but transition metal-containing compounds such as lanthanides (Nd, etc.), Ti, Co, Ni-containing compounds can be used as the catalyst. Further, Al and B-containing compounds can be used as a promoter.

The lanthanide-containing compound (such as an Nd-containing compound) is not particularly limited as long as it contains an element having an atomic number of 57 to 71. For example, carboxylate, β-diketone complex, alkoxide, phosphate, or phosphorous acid Examples thereof include salts and halides, and carboxylates, alkoxides, and β-diketone complexes are preferable from the viewpoint of ease of handling and improvement of tire performance. Examples of the Ti-containing compound include three substituents selected from halogen, alkoxyl groups, and alkyl groups, including one cyclopentadienyl group, indenyl group, substituted cyclopentadienyl group, or substituted indenyl group. A compound having one alkoxysilyl group is preferable from the viewpoint of improving catalyst performance and tire performance. Examples of the Co-containing compound include halides, carboxylates, β-diketone complexes, organic base complexes, and organic phosphine complexes. Examples of Ni-containing compounds include, but are not limited to, halides, carboxylates, β-diketone complexes, organic base complexes, and the like.

The Al-containing compound used as a co-catalyst is not particularly limited as long as it is an organic aluminoxane, a halogenated organoaluminum compound, an organoaluminum compound, a hydrogenated organoaluminum compound, etc., but methylaluminoxane, ethylaluminoxane, propylaluminoxane, butyl Aluminoxane, isobutylaluminoxane, octylaluminoxane, hexylaluminoxane, chloroaluminoxane, trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, diethylaluminum hydride, diisobutylaluminum hydride, dimethylaluminum chloride, diethylaluminum chloride, methylaluminum dichloride, ethylaluminium Dichloride are preferred, they may be used in mixture. Examples of the B-containing compound include compounds containing anion species such as tetraphenylborate, tetrakis (pentafluorophenyl) borate, and (3,5-bistrifluoromethylphenyl) borate.

In the preparation of the polar group-containing copolymer, when a compound having a protonic property is used among the polar group-containing vinyl compounds, the copolymer is first deactivated in order to prevent inhibition of the polymerization reaction. It is preferable to make it. The inactivation method is not particularly limited. For example, before the copolymerization reaction of the polar group-containing vinyl compound represented by the formula (I) and the conjugated diene compound, the deactivation method is represented by the formula (I). A polar group-containing vinyl compound and the following general formula (II);
M (R ⁴ ) _m (II)
(In formula (II), M represents aluminum, boron, silicon, or titanium. R ⁴ represents an aliphatic or alicyclic hydrocarbon group having 1 to 8 carbon atoms, an aliphatic or aliphatic group having 1 to 8 carbon atoms. A cyclic alkoxy group or halogens, which may be the same or different, m represents an integer of 3 or 4)
The compound represented by these is made to react. Thereby, polar groups such as hydroxyl groups of the polar group-containing vinyl compound which is one of the inhibition factors of the polymerization reaction are inactivated, and the reaction product obtained by the reaction is copolymerized with the conjugated diene compound. Thus, the desired polar group-containing copolymer can be produced satisfactorily. When the inactivation treatment is not performed, that is, when the polar group-containing vinyl compound is not reacted with the compound of the general formula (II), the polymerization reaction is remarkably slow or the polymerization reaction does not proceed in many cases.

The number of carbon atoms of R ⁴ is from 1 to 6 are preferred. Examples of the aliphatic or alicyclic hydrocarbon group for R ⁴ include the same groups as those described above for R ^3. Examples of the aliphatic or alicyclic alkoxy group include the aliphatic or alicyclic hydrocarbon group. An alkoxy group corresponding to the group can be mentioned. In addition, examples of halogens for R ⁴ include chlorine, bromine, fluorine, and the like.

（式（ＩＩＩ）、（ＩＶ）中、Ｒ^５は、炭素数１〜８の脂肪族若しくは脂環族炭化水素基を表し、同一であっても異なっていてもよい。Ｒ^６は、炭素数１〜８の脂肪族若しくは脂環族炭化水素基、又は炭素数１〜８の脂肪族若しくは脂環族アルコキシ基を表し、同一であっても異なっていてもよい。Ｍ^１は、ケイ素又はチタンを表す。）
Ｒ^５、Ｒ^６の炭素数１〜８の脂肪族若しくは脂環族炭化水素基としては、例えば、上記Ｒ^４と同様の基を挙げることができる。Ｒ^６の炭素数１〜８の脂肪族若しくは脂環族アルコキシ基としては、該脂肪族若しくは脂環族炭化水素基に対応するアルコキシ基が挙げられる。 As the compound represented by the general formula (II), organometallic compounds represented by the following general formulas (III) and (IV) can be suitably used.

(In the formulas (III) and (IV), R ⁵ represents an aliphatic or alicyclic hydrocarbon group having 1 to 8 carbon atoms, and may be the same or different. R ⁶ represents the number of carbon atoms. Represents an aliphatic or alicyclic hydrocarbon group having 1 to 8 or an aliphatic or alicyclic alkoxy group having 1 to 8 carbon atoms, which may be the same or different, and M ¹ is silicon or titanium Represents.)
Examples of the aliphatic or alicyclic hydrocarbon group having 1 to 8 carbon atoms of R ^5, R ^6, for example, include the same groups as the above R ^4. Examples of the aliphatic or alicyclic alkoxy group having 1 to 8 carbon atoms of R ⁶ include an alkoxy group corresponding to the aliphatic or alicyclic hydrocarbon group.

The compound represented by the formula (III) is not particularly limited, and examples thereof include trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, dimethylaluminum chloride, diisopropylaluminum chloride, diisobutylaluminum chloride, and ethylaluminum dichloride. It is done. It does not specifically limit as a compound represented by Formula (IV), For example, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetra-n-propoxysilane, tetraisobutoxysilane, tetra-n-butoxysilane, Diethoxydimethylsilane, ethoxytrimethylsilane, diethoxydiethylsilane, ethoxytriethylsilane, tetramethoxytitanium, tetraethoxytitanium, tetraisopropoxytitanium, tetra-n-propoxytitanium, tetraisobutoxytitanium, tetra-n-butoxytitanium, Examples include tetra-t-butoxy titanium and tetra-sec-butoxy titanium.

Although the container used for reaction of the said polar group containing vinyl compound and the compound represented by the said general formula (II) is not specifically limited, It is preferable to carry out at least in inert gas, such as nitrogen gas and argon.

There is no restriction | limiting in particular as a method of manufacturing a polar group containing copolymer using the said catalyst as a polymerization initiator, A conventionally well-known method can be used.
Specifically, in an organic solvent inert to the reaction, for example, a hydrocarbon solvent such as an aliphatic, alicyclic or aromatic hydrocarbon compound, the reaction product of formula (I) and formula (II) The desired polar group-containing copolymer can be obtained by copolymerizing the conjugated diene compound with the lanthanide, Ti, Co, Ni-containing compound as a catalyst and the Al, B-containing compound as a co-catalyst. it can.

The hydrocarbon solvent is preferably one having 3 to 8 carbon atoms, for example, propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propene, 1-butene, isobutene, trans- Examples include 2-butene, cis-2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene, dichloromethane, chloroform, chlorobenzene, and the like. These may be used alone or in combination of two or more.

The polar group-containing copolymer contains 0.1 to 20% by mass of a structural unit A having 50% by mass or less of units derived from the conjugated diene compound and 50% by mass or more of units derived from the polar group-containing vinyl compound. Including 80 to 99.9% by mass of structural unit B having 60% by mass or more of units derived from the conjugated diene compound and 40% by mass or less of units derived from the polar group-containing vinyl compound, and having the polarity What has this structural unit A in the terminal part of a group containing copolymer is preferable. That is, at least the terminal part of the polar group-containing copolymer includes a structural unit A having 50% by mass or more of units derived from the polar group-containing vinyl compound, and the structural unit B having only 40% by mass or less of the unit. Is also present in the copolymer. Thereby, the dispersibility of a filler is improved. As such a copolymer, for example, at the end of the polymer portion I having 60% by mass or more of units derived from the conjugated diene compound and 40% by mass or less of units derived from the polar group-containing vinyl compound in a random structure, 50% by mass or less of units derived from the conjugated diene compound (preferably 5% by mass or less, more preferably 2% by mass or less, still more preferably 0% by mass) and 50% by mass or more of units derived from the polar group-containing vinyl compound. (Preferably 95% by mass or more, more preferably 98% by mass or more, and still more preferably 100% by mass). Here, when the polymer part II has 100% by mass of units derived from the polar group-containing vinyl compound, the copolymer is formed from the polar group-containing vinyl compound at the terminal of the polymer part I having a random structure. It has the block structure which becomes.

The polar group-containing copolymer having the structural units A and B is, for example, an active terminal obtained by using the transition metal-containing compound as a catalyst and copolymerizing the conjugated diene compound and the polar group-containing vinyl compound. It can be obtained by further reacting the above-mentioned polar group-containing vinyl compound with the active terminal. Specifically, in the inert organic solvent, the reaction product of the formula (I) and the formula (II) and the conjugated diene compound are copolymerized using the catalyst and the cocatalyst, thereby changing the active terminal. A copolymer solution having the following polar group-containing copolymer is obtained by further reacting the obtained copolymer solution with the reaction products of the formulas (I) and (II). Can be obtained.

In this invention, after this reaction, alcohol etc. can be added as needed for the purpose of stopping a known anti-aging agent or polymerization reaction. By adding an alcohol after the polymerization reaction, the compound represented by the formula (II) bonded to the polar group such as a hydroxyl group of the polar group-containing vinyl compound is eliminated, so that the polar group and the filler are easily bonded. Thus, the dispersibility of the filler is further increased.

The content of the polar group-containing vinyl compound in the polar group-containing copolymer is preferably 0.03% by mass or more, more preferably 0.05% by mass or more, and still more preferably 0.1% by mass or more. The content is preferably 40% by mass or less, more preferably 30% by mass or less, still more preferably 20% by mass or less, and particularly preferably 10% by mass or less. If it is less than 0.03% by mass, the effect of improving wear resistance is difficult to obtain, whereas if it exceeds 40% by mass, the cost tends to be high. In addition, in this invention, content of a polar group containing vinyl compound is measured by the method of the below-mentioned Example.

In view of obtaining good abrasion resistance, 1,3-butadiene is preferably used as the conjugated diene compound. The content of 1,3-butadiene in 100% by mass of the conjugated diene compound in the polar group-containing copolymer is preferably 80% by mass or more, more preferably 85% by mass or more, still more preferably 90% by mass or more, particularly Preferably it is 100 mass%. That is, the polar group-containing copolymer is preferably a modified butadiene rubber.

The polar group-containing copolymer has a cis content of the double bond portion of the conjugated diene compound in the copolymer (the cis content of the double bond in the conjugated diene compound unit in the polar group-containing copolymer) is 80 mol. % Or more, preferably 90 mol% or more. If it is less than 80 mol%, flexibility and wear resistance tend to deteriorate. In the present invention, the amount of cis component (cis content) is a value obtained by the measurement method of Examples described later.

The weight average molecular weight Mw of the polar group-containing copolymer is preferably 1.0 × 10 ^{3 to} 2.0 × 10 ⁶ , and the lower limit is more preferably 1.0 × 10 ⁴ , and 2.0 × 10 6. ⁴ is more preferable. The upper limit is more preferably 1.0 × 10 ⁶ . If the weight average molecular weight is less than 1.0 × 10 ³ , the hysteresis loss is large and it is difficult to obtain sufficient fuel efficiency, and the wear resistance tends to be lowered. On the other hand, when it exceeds 2.0 × 10 ⁶ , workability tends to be remarkably lowered.

Moreover, Mw / Mn of the said polar group containing copolymer becomes like this. Preferably it is 4.5 or less, More preferably, it is 4.0 or less. If it exceeds 4.5, the amount of the low molecular weight component increases, so that the wear resistance tends to deteriorate.
In addition, in this invention, a weight average molecular weight (Mw) and a number average molecular weight (Mn) are measured by the method of the below-mentioned Example.

In the rubber composition of the present invention, the content of the polar group-containing copolymer is the total amount of rubber components (including the polar group-containing copolymer, modified natural rubber, and other diene rubber components described later). ) In 100% by mass, preferably 5% by mass or more, more preferably 7% by mass or more. If it is less than 5% by mass, the effect of improving wear resistance tends to be difficult to obtain. The content is preferably 60% by mass or less, more preferably 30% by mass or less. If it exceeds 60% by mass, the fracture characteristics tend to deteriorate.

In the rubber composition of the present invention, modified natural rubber is used together with the polar group-containing copolymer. High performance cis-content diene rubber (polar group-containing copolymer) with a polar group in the main chain and modified natural rubber are used together to provide all the performances of wear resistance, fuel efficiency, fracture characteristics, and processability. Can be obtained in a well-balanced manner.

The modified natural rubber (HPNR) has a phosphorus content of 200 ppm or less. If it exceeds 200 ppm, the gel amount will increase during storage, and the tan δ of the vulcanized rubber will increase and the fuel efficiency will deteriorate, or the Mooney viscosity of the unvulcanized rubber will increase and the processability will tend to deteriorate. In addition, there is a possibility that low fuel consumption, wear resistance, fracture characteristics and workability cannot be improved in a well-balanced manner. The phosphorus content is preferably 150 ppm or less, and more preferably 100 ppm or less. Here, the phosphorus content can be measured by a conventional method such as ICP emission analysis. Phosphorus is derived from phospholipids (phosphorus compounds).

In the modified natural rubber, the nitrogen content is preferably 0.3% by mass or less, and more preferably 0.15% by mass or less. If the nitrogen content exceeds 0.3% by mass, the Mooney viscosity tends to increase during storage and the processability tends to deteriorate, and the balance may not be improved. The nitrogen content can be measured by a conventional method such as Kjeldahl method. Nitrogen is derived from protein.

The gel content in the modified natural rubber is preferably 20% by mass or less, more preferably 10% by mass or less, and still more preferably 7% by mass or less. If it exceeds 20% by mass, the Mooney viscosity tends to increase and the processability tends to deteriorate, and the balance may not be improved. The gel content means a value measured as an insoluble content with respect to toluene which is a nonpolar solvent, and may be simply referred to as “gel content” or “gel content” below. The measuring method of the content rate of a gel part is as follows. First, a natural rubber sample is soaked in dehydrated toluene, light-shielded in the dark and left for 1 week, and then the toluene solution is centrifuged at 1.3 × 10 ⁵ rpm for 30 minutes to obtain an insoluble gel content and a toluene soluble content. Isolate. Methanol is added to the insoluble gel and solidified, and then dried, and the gel content is determined from the ratio between the mass of the gel and the original mass of the sample.

The modified natural rubber is preferably substantially free of phospholipids. “Substantially no phospholipid is present” represents a state in which a natural rubber sample is extracted with chloroform and a peak due to phospholipid does not exist at −3 ppm to 1 ppm in ³¹ P NMR measurement of the extract. The peak of phosphorus present at -3 ppm to 1 ppm is a peak derived from the phosphate structure of phosphorus in the phospholipid.

As a method for producing the modified natural rubber, a process (A) for obtaining a saponified natural rubber latex by saponifying a natural rubber latex, and a phosphorus content contained in the obtained saponified natural rubber latex The manufacturing method including the process (B) wash | cleaned until it becomes 200 ppm or less is mentioned. Specifically, first, a natural rubber latex is saponified with an alkali to prepare a saponified natural rubber latex, and then the agglomerated rubber obtained by agglomerating the saponified natural rubber latex is contained in the rubber. A modified natural rubber (saponified natural rubber) can be produced by a method such as washing and drying until the phosphorus content is 200 ppm or less.

In the production method described above, the saponification treatment can be performed by adding an alkali and, if necessary, a surfactant to natural rubber latex and allowing to stand at a predetermined temperature for a certain time. In addition, you may perform stirring etc. as needed. According to the above production method, the phosphorus compound separated by saponification is washed away, so that the phosphorus content of the natural rubber can be suppressed. Moreover, since the protein in natural rubber is decomposed by the saponification treatment, the nitrogen content of the natural rubber can be suppressed. In the present invention, alkali can be added to natural rubber latex for saponification, but by adding it to natural rubber latex, there is an effect that saponification can be efficiently performed.

Natural rubber latex is collected as sap of heavy trees and contains rubber, water, proteins, lipids, inorganic salts, etc., and the gel content in rubber is thought to be based on the complex presence of various impurities. . In the present invention, raw latex produced by tapping a heavy tree or purified latex concentrated by centrifugation is used. Furthermore, high ammonia latex to which ammonia is added by a conventional method may be used in order to prevent the progress of decay due to bacteria present in the raw rubber latex and to avoid coagulation of the latex.

Examples of the alkali used for the saponification treatment include sodium hydroxide, gallium hydroxide, calcium hydroxide, and amine compounds. From the viewpoint of the effect of the saponification treatment and the influence on the stability of the natural rubber latex, the hydroxide is particularly preferred. Sodium or gallium hydroxide is preferably used.

The amount of alkali added is not particularly limited, but the lower limit is preferably 0.1 parts by mass or more and more preferably 0.3 parts by mass or more with respect to 100 parts by mass of the solid content of the natural rubber latex. The upper limit of the addition amount is preferably 12 parts by mass or less, more preferably 10 parts by mass or less, further preferably 7 parts by mass or less, and particularly preferably 5 parts by mass or less. If the amount of alkali added is less than 0.1 parts by mass, saponification may take time. Conversely, if the amount of alkali added exceeds 12 parts by mass, the natural rubber latex may be destabilized.

As the surfactant, at least one of an anionic surfactant, a nonionic surfactant and an amphoteric surfactant can be used. Among these, examples of the anionic surfactant include carboxylic acid-based, sulfonic acid-based, sulfate ester-based and phosphate ester-based anionic surfactants. Examples of the nonionic surfactant include nonionic surfactants such as polyoxyalkylene ester, polyoxyalkylene ester, polyhydric alcohol fatty acid ester, glycolipid ester, and alkylpolyglycoside. Examples of the amphoteric surfactant include amphoteric surfactants such as amino acid type, betaine type, and amine oxide type. Among these, an anionic surfactant is preferable, and a sulfonic acid anionic surfactant is more preferable.

The addition amount of the surfactant is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 1.1 parts by mass or more with respect to 100 parts by mass of the solid content of the natural rubber latex. Preferably, 2.0 parts by mass or more is particularly preferable. The upper limit of the addition amount is preferably 6.0 parts by mass or less, more preferably 5.0 parts by mass or less, and further preferably 3.5 parts by mass or less. If the addition amount of the surfactant is less than 0.01 parts by mass, the natural rubber latex may become unstable during the saponification treatment. On the other hand, if the amount added exceeds 6.0 parts by mass, the natural rubber latex may become too stable and coagulation may become difficult. Moreover, when it is 1.1 mass parts or more, the phosphorus content, the nitrogen content, and the gel content in the natural rubber can be further reduced.

The temperature of the saponification treatment can be appropriately set within the range where the saponification reaction with alkali can proceed at a sufficient reaction rate and the natural rubber latex does not cause alteration such as coagulation, but is usually 20 to 70 ° C. It is preferable that 30 to 70 ° C is more preferable. Further, the treatment time is 3 to 48 hours in consideration of both sufficient treatment and productivity improvement, depending on the treatment temperature when the treatment is performed with natural rubber latex standing. It is preferable that 3 to 24 hours is more preferable.

After completion of the saponification reaction, the agglomerated rubber is crushed and washed to reduce the phosphorus content. Examples of the aggregation method include a method of adjusting pH by adding an acid such as formic acid. Examples of the washing treatment include a method of diluting the rubber with water and washing it, and then performing a centrifugal separation treatment to take out the rubber. When centrifuging, it is first diluted with water so that the rubber content of the natural rubber latex is 5 to 40% by mass, preferably 10 to 30% by mass. Then, it may be centrifuged at 5000 to 10000 rpm for 1 to 60 minutes, and washing may be repeated until a desired phosphorus content is obtained. The modified natural rubber in the present invention is obtained by drying after completion of the washing treatment.

In the above production method, the saponification, washing and drying steps are preferably completed within 15 days after collecting the natural rubber latex. More preferably, it is within 10 days, and more preferably within 5 days. This is because the gel content increases if the sample is left for more than 15 days without solidification after collection.

In the rubber composition of the present invention, the content of the modified natural rubber in 100% by mass of the rubber component is preferably 40% by mass or more. If it is less than 40% by mass, excellent fuel efficiency may not be obtained. The content is preferably 95% by mass or less, more preferably 90% by mass or less. If it exceeds 95% by mass, the wear resistance may deteriorate.

The rubber composition of the present invention may contain other diene rubber components in addition to the polar group-containing copolymer and the modified natural rubber. Examples of other diene rubber components include natural rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), Examples include acrylonitrile butadiene rubber (NBR), butyl rubber (IIR), and halogenated butyl rubber (X-IIR). Of these, NR, BR, and SBR are preferable because they exhibit a good balance of wear resistance and low fuel consumption. These rubbers may be used alone or in combination of two or more.

The rubber composition of the present invention preferably contains carbon black as a reinforcing agent. By compounding carbon black, the reinforcing property can be enhanced, and the effects of the present invention can be obtained satisfactorily.

The nitrogen adsorption specific surface area _(N 2 SA) of carbon black is ^preferably 30m ² / g~280m 2 / g, the lower limit is 100 m ² / g or more, and more preferable upper limit is not more than 250m ² / g. If the N ₂ SA of the carbon black is less than 30 m ² / g, sufficient reinforcement cannot be obtained, and the wear resistance tends to decrease. On the other hand, when it exceeds 280 m ² / g, the dispersibility is inferior and the wear resistance tends to be lowered.
In addition, the nitrogen adsorption specific surface area of carbon black is calculated | required by A method of JISK6217.

As for content of carbon black, 5-150 mass parts is preferable with respect to 100 mass parts of all the rubber components. The lower limit is more preferably 10 parts by mass or more, and still more preferably 20 parts by mass or more. The upper limit is more preferably 100 parts by mass or less. When the content of carbon black is less than 5 parts by mass, the wear resistance tends to decrease. On the other hand, when it exceeds 150 mass parts, there exists a tendency for workability to deteriorate. Carbon black may be used alone or in combination of two or more.

In the present invention, an anti-aging agent is usually used, and an amine-based anti-aging agent is preferably used from the viewpoint of excellent wear resistance and fracture characteristics. Examples of amine-based antioxidants include diphenylamine-based and p-phenylenediamine-based amine derivatives. Examples of the diphenylamine derivative include p- (p-toluenesulfonylamide) -diphenylamine. Examples of p-phenylenediamine derivatives include N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine (6PPD), N-phenyl-N′-isopropyl-p-phenylenediamine (IPPD). ) And the like.

The content of the anti-aging agent is preferably 1.2 parts by mass or more, more preferably 1.4 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, this content becomes like this. Preferably it is 6 mass parts or less, More preferably, it is 4 mass parts or less, More preferably, it is 3 mass parts or less. When HPNR is produced, there is a tendency for the deterioration preventing component to be removed during the saponification treatment of NR, but the deterioration of the performance due to the removal of the deterioration preventing component can be suppressed by blending the anti-aging agent within the above range.

In the rubber composition of the present invention, the oil content is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and still more preferably 2 parts by mass or less with respect to 100 parts by mass of the total rubber components. In the present invention, good processability can be obtained by HPNR, and the amount of oil can be reduced. Therefore, it is possible to prevent the wear resistance and the degradation characteristics from deteriorating due to the blending of oil.

The rubber composition of the present invention may contain various compounding agents and additives blended for tires such as other reinforcing agents, vulcanizing agents, vulcanization accelerators, and general rubber compositions. Moreover, the content of these compounding agents and additives can also be set to general amounts.

As a method for producing the rubber composition of the present invention, known methods can be used. For example, the above components are kneaded using a rubber kneading device such as an open roll or a Banbury mixer, and then vulcanized (crosslinked). It can be manufactured by a method or the like. In the present invention, since the modified natural rubber is used, the kneading step can be carried out satisfactorily without performing the kneading step, and a desired rubber composition can be produced.

The rubber composition of the present invention can be used for each member of a tire, and in particular, can be suitably used for a tread (cap tread) of a heavy duty tire (particularly for trucks and buses).

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

Hereinafter, various chemicals used in the production examples will be described together. In addition, the chemical | medical agent refine | purified according to the usual method as needed.
Natural rubber latex: Field latex obtained from Taitex Co., Ltd. Surfactant: Emal-E (Polyoxyethylene lauryl ether sodium sulfate) manufactured by Kao Corporation
NaOH: NaOH manufactured by Wako Pure Chemical Industries, Ltd.
Cyclohexane: anhydrous cyclohexane isopropanol manufactured by Kanto Chemical Co., Ltd .: isopropanolamine monomer manufactured by Kanto Chemical Co., Ltd .: 2- (1-cyclohexenyl) ethylamine silane monomer manufactured by Tokyo Chemical Industry Co., Ltd. (1): Sigma-Aldrich Trimethoxy (7-octen-1-yl) silane (80% by mass) manufactured by
Silane monomer (2): 5- (triethoxysilyl) -2-norbornene (97% by mass) manufactured by Tokyo Chemical Industry Co., Ltd.
5-hexen-1-ol: Neodymium 5-hexen-1-ol ethylhexanoate manufactured by Tokyo Chemical Industry Co., Ltd .: Neodymium ethylhexanoate (neodymium ethylhexanoate / toluene manufactured by Wako Pure Chemical Industries, Ltd.) (Solution: 0.2 mol / L)
TIBA solution: 1M-triisobutylaluminum / hexane solution manufactured by Tosoh Finechem Corp. DEAC solution: 1M-diethylaluminum chloride / hexane solution DIBAH solution manufactured by Bundleso Finechem Corp .: manufactured by Tosoh Finechem Corp. 1M-isodibutylaluminum hydride / toluene solution butadiene: 1,3-butadiene PMAO (polymethylaluminosiloxane) manufactured by Takachiho Chemical Co., Ltd .: PMAO manufactured by Tosoh Finechem Corporation (Al: 6.8% by mass) )
Methanol: Methanol BHT manufactured by Kanto Chemical Co., Ltd .: 2,6-tert-butyl-p-cresol manufactured by Kanto Chemical Co., Ltd.

Production Example 1 (Synthesis of saponified natural rubber A)
After adjusting the solid rubber latex solids concentration (DRC) to 30% (w / v), 1000 g of natural rubber latex was added with 10 g of Emal-E and 20 g of NaOH, followed by saponification at room temperature for 48 hours. Natural rubber latex was obtained. Water was added to the latex to dilute to DRC 15% (w / v), and then formic acid was added with slow stirring to adjust the pH to 4.0 to 4.5 to cause aggregation. The agglomerated rubber was pulverized, washed repeatedly with 1000 ml of water, and then dried at 110 ° C. for 2 hours to obtain a solid rubber (saponified natural rubber A).

Production Example 2 (Synthesis of saponified natural rubber B)
A solid rubber (saponified natural rubber B) was obtained in the same manner as in Production Example 1 except that the amount of NaOH added was changed to 15 g.

With respect to the solid rubber obtained in Production Examples 1 and 2 and the TSR used in the evaluation of the rubber composition described later, the nitrogen content, phosphorus content, and gel content were measured by the methods described below. The results are shown in Table 1.

(Measurement of nitrogen content)
The nitrogen content was measured using CHN CORDER MT-5 (manufactured by Yanaco Analytical Industries). For the measurement, first, a calibration curve for determining the nitrogen content was prepared using antipyrine as a standard substance. Next, about 10 mg of natural rubber obtained in each production example was weighed, and an average value was obtained from the measurement results of three times to obtain the nitrogen content of the sample.

(Measurement of phosphorus content)
The phosphorus content was determined using an ICP emission spectrometer (ICPS-8100, manufactured by Shimadzu Corporation).
In addition, ³¹ P-NMR measurement of phosphorus uses an NMR analyzer (400 MHz, AV400M, manufactured by Nippon Bruker Co., Ltd.), and uses a measurement peak of P atom in an 80% aqueous phosphoric acid solution as a reference point (0 ppm), and raw rubber with chloroform. More extracted components were purified, dissolved in CDCl ₃ and measured.

(Measurement of gel content)
A raw rubber sample 70.00 mg cut to 1 mm × 1 mm was weighed, 35 mL of toluene was added thereto, and the mixture was allowed to stand in a cool dark place for 1 week. Subsequently, centrifugation was performed to precipitate a gel component insoluble in toluene, the soluble component of the supernatant was removed, and only the gel component was solidified with methanol, and then dried and the mass was measured. The gel content (%) was determined by the following formula.
Gel content (mass%) = [mass mg after drying / mg of initial sample] × 100

As shown in Table 1, the saponified natural rubber (HPNR) had a reduced nitrogen content, phosphorus content, and gel content as compared to TSR. Further, in the ³¹ P NMR measurement of the extract extracted from the modified natural rubber obtained in Production Examples 1 and 2, no peak due to phospholipid was detected at -3 ppm to 1 ppm.

The analysis of the monomer and polymer obtained by the following was performed by the following method.
(Measurement of weight average molecular weight Mw, number average molecular weight Mn)
For Mw and Mn, a GPC-8000 series apparatus manufactured by Tosoh Corporation was used, a differential refractometer was used as a detector, and the molecular weight was calibrated with standard polystyrene.

(Measurement of hydroxyl group-containing vinyl compound content in polymer and cis content in butadiene unit contained in polymer)
The synthesized polymer was dissolved in 15 ml of toluene per gram, slowly poured into 30 ml of methanol, purified and dried, and used as a deuterated chloroform solution. The measurement was performed using a JNM-ECA series NMR apparatus manufactured by JEOL Ltd. Signal intensity ratio of 1,4-bond (5.30-5.50 ppm) and 1,2-bond (4.94-5.03 ppm) by ¹ H-NMR measurement, and cis bond by ¹³ C-NMR measurement Calculation was performed from the signal intensity ratio of (25.5 ppm) and trans bond (32.8 ppm).

(Measurement of amino group introduction rate in polymer)
The introduction amount of the amine monomer was measured using the NMR apparatus, and was calculated from the signal intensity ratio of 2.73-2.80 ppm (2H) based on the amine monomer and the signal intensity ratio based on the butadiene unit described above.

(Measurement of silane introduction rate in polymer)
It estimated from each area ratio and preparation amount of the silane monomer before and behind reaction using Shimadzu Corporation gas chromatography GC2010.

Production Example 3 (Synthesis of amine monomer solution)
A 200 cc glass container was purged with nitrogen, and 40 ml of cyclohexane and 30 mmol of amine monomer were added and stirred. Further, 80 ml of TIBA solution was added dropwise, and the mixture was stirred for 30 minutes at room temperature after completion of the addition. The obtained solution was stored in a refrigerator while keeping a nitrogen atmosphere under light shielding.

Production Example 4 (Synthesis of hydroxyl group-containing monomer solution)
A 200 cc glass container was purged with nitrogen, and 50 ml of cyclohexane and 150 mmol of 5-hexen-1-ol were added and stirred. Further, 170 ml of TIBA solution was added dropwise, and the mixture was stirred at room temperature for 30 minutes after completion of the addition. The obtained solution was stored in a refrigerator while keeping a nitrogen atmosphere under light shielding.

Production Example 5 (Synthesis of catalyst solution (1))
A 50 ml glass container was purged with nitrogen, 8 ml of a cyclohexane solution of butadiene (2.0 mol / L), 1 ml of a neodymium ethylhexanoate / toluene solution (0.2 mol / L) and 8 ml of PMAO were added and stirred. After 5 minutes, 5 ml of DIBAH solution was added, and after 5 minutes, 2 ml of DEAC solution was added to obtain catalyst solution (1).

Production Example 6 (Synthesis of polymer (1))
The reaction kettle (3L pressure-resistant stainless steel container) was purged with nitrogen, and 1800 ml of cyclohexane, 75 g of butadiene, 1 ml of TIBA solution, and 22.8 ml of amine monomer solution were placed in a sealed atmosphere while maintaining a nitrogen atmosphere. 1.5 ml of the solution (1) was added and stirred while maintaining 30 ° C. After 3 hours, 10 ml of 0.01M-BHT / isopropanol solution was dropped into the reaction kettle to complete the reaction. The reaction solution was cooled and then added to 3 L of methanol separately prepared, and the resulting precipitate was air-dried overnight and further dried under reduced pressure for 2 days to obtain a polymer (1). The yield was about 74.2 g. As a result of analysis, the polymer (1) obtained has a number average molecular weight of 22.9 × 10 ⁴ , Mw / Mn of 2.6, a cis content in the butadiene unit of 99.0 mol%, and an amine monomer content. Was 0.28 mol% (0.6 mass%).

Production Example 7 (Synthesis of polymer (2))
A polymer (2) was obtained in the same manner as in Production Example 6 except that the amine monomer solution was changed to 0.80 ml of the silane monomer (1) in Production Example 6. The yield was about 71.4g. As a result of analysis, the polymer (2) obtained has a number average molecular weight of 19.1 × 10 ⁴ , Mw / Mn of 2.9, a cis content in the butadiene unit of 98.7 mol%, and a silane monomer (1). The content of was 0.18 mol% (0.8 mass%).

Production Example 8 (Synthesis of polymer (3))
A polymer (3) was obtained in the same manner as in Production Example 6 except that the amine monomer solution in Production Example 6 was changed to 0.73 ml of the silane monomer (2). The yield was about 71.4g. As a result of analysis, the polymer (3) obtained has a number average molecular weight of 19.3 × 10 ⁴ , Mw / Mn of 3.1, a cis content in the butadiene unit of 98.7 mol%, and a silane monomer (2). The content of was 0.18 mol% (0.7 mass%).

Production Example 9 (Synthesis of polymer (4))
In Production Example 6, the same procedure as in Production Example 6 was performed, except that the amine monomer solution was not used, to obtain a polymer (4). The yield was about 73.5g. As a result of analysis, the number average molecular weight of the obtained polymer (4) was 21.1 × 10 ⁴ , Mw / Mn was 2.5, and the cis content in the butadiene unit was 99.2 mol%.

Production Example 10 (Synthesis of polymer (5))
A polymer (5) was obtained in the same manner as in Production Example 6 except that the amine monomer solution was changed to a hydroxyl group-containing monomer solution in Production Example 6. The yield was about 96%. As a result of analysis, the weight average molecular weight of the obtained polymer was 32 × 10 ⁴ , Mw / Mn = 3.2, the content of the hydroxyl group-containing monomer (5-hexen-1-ol) was 0.3% by mass, butadiene The cis content in the unit was about 98 mol%.

Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
Polymer, saponified natural rubber: prepared in the above production example BR (1): BR150B manufactured by Ube Industries, Ltd.
BR (2): BR1250H manufactured by Nippon Zeon Co., Ltd.
Natural rubber: TSR
Carbon black (1): Dia Black I (N ₂ SA: 114 m ² / g) manufactured by Mitsubishi Chemical Corporation
Carbon Black (2): Show Black N220 (N ₂ SA: 111 m ² / g) manufactured by Cabot Japan
Oil: Mineral oil PW-380 manufactured by Idemitsu Kosan Co., Ltd.
Zinc oxide: Zinc Hana No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Wax: Sunnock wax manufactured by Ouchi Shinsei Chemical Co., Ltd. Stearic acid: Stearic acid camellia anti-aging agent manufactured by NOF Corporation Nocrack 6C (N-1,3 dimethylbutyl-N′-phenyl-p-phenylenediamine) manufactured by Chemical Industry Co., Ltd.
Sulfur: powder sulfur vulcanization accelerator NS manufactured by Tsurumi Chemical Co., Ltd. NS: Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Vulcanization accelerator CZ: Noxeller CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Vulcanization accelerator D: Noxeller D (N, N′-diphenylguanidine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

Examples 1-6 and Comparative Examples 1-5
In accordance with the formulation shown in Table 2, 1.7 L Banbury was used to knead chemicals other than sulfur and a vulcanization accelerator. Next, using a roll, sulfur and a vulcanization accelerator were added to the obtained kneaded product and kneaded to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was press vulcanized at 150 ° C. for 30 minutes to obtain a vulcanized rubber composition. The following tests were performed using the obtained vulcanized rubber composition. In Table 2, the reference comparative example was Comparative Example 5.

Examples 7-12 and Comparative Examples 6-7
In accordance with the formulation shown in Table 3, 1.7 L Banbury was used to knead chemicals other than sulfur and a vulcanization accelerator. Next, using a roll, sulfur and a vulcanization accelerator were added to the obtained kneaded product and kneaded to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was press vulcanized at 170 ° C. for 20 minutes to obtain a vulcanized rubber composition. The following tests were performed using the obtained vulcanized rubber composition. In Table 3, the reference comparative example was Comparative Example 7.

In addition, about TSR, 0.2 mass part of peptizer was added with respect to 100 mass parts of the rubber component of TSR, and it was used after masticating beforehand using a 1.7L Banbury mixer. On the other hand, saponified natural rubber (HPNR) was not masticated.

(Mooney viscosity index)
In accordance with JIS K 6300-1 “Unvulcanized rubber—physical properties—Part 1: Determination of viscosity and scorch time using Mooney viscometer”, it was heated by preheating for 1 minute using a Mooney viscosity tester. Under the temperature condition of 130 ° C., the small rotor was rotated, and the Mooney viscosity (ML _{1 +} 4/130 ° C.) of the unvulcanized rubber composition after 4 minutes was measured. And the measurement result of the reference | standard comparative example was set to 100, and the Mooney viscosity of each mixing | blending was shown by the index | exponent by the following formula. The larger the index, the lower the Mooney viscosity and the better the workability.
(Mooney viscosity index) = (Mooney viscosity of reference comparative example) / (Mooney viscosity of each formulation) × 100

(Rolling resistance index)
Using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.), the loss tangent (tan δ) of the vulcanized rubber composition was calculated under the conditions of a temperature of 70 ° C., an initial strain of 10%, a dynamic strain of 2%, and a frequency of 10 Hz. It was measured. Then, tan δ of the reference comparative example was set to 100, and tan δ of each formulation was displayed as an index (rolling resistance index) by the following calculation formula. A larger index indicates lower rolling resistance and better fuel efficiency.
(Rolling resistance index) = (tan δ of reference comparative example) / (tan δ of each formulation) × 100

(Rubber strength index)
A No. 3 dumbbell-shaped rubber test piece was prepared using the vulcanized rubber composition, and subjected to a tensile test in accordance with JIS K 6251 “Vulcanized Rubber and Thermoplastic Rubber-Determination of Tensile Properties”. ) And elongation at break (EB) were measured, and rubber strength (TB × EB) was calculated. Then, the rubber strength of the reference comparative example was set to 100, and the rubber strength of each compound was indicated by an index by the following calculation formula. The larger the index, the better the rubber strength (destructive property).
(Rubber Strength Index) = (TB × EB of each formulation) / (TB × EB of Reference Comparative Example) × 100

(Abrasion resistance index)
Using a LAT tester (Laboratory Ablation and Skid Tester), the volume loss of the vulcanized rubber composition was measured under the conditions of a load of 50 N, a speed of 20 km / h, and a slip angle of 5 °. Then, the volume loss amount of the reference comparative example was set to 100, and the volume loss amount of each formulation was displayed as an index according to the following calculation formula. It shows that it is excellent in abrasion resistance, so that an index | exponent is large.
(Abrasion resistance index) = (volume loss amount of reference comparative example) / (volume loss amount of each formulation) × 100

From Tables 2 and 3, in Examples using a high cis content polar group-containing copolymer (polymers (1) to (3), (5)) and HPNR, low fuel consumption, wear resistance, fracture The characteristics and workability were improved in a well-balanced manner.

Claims (14)

Containing a rubber component comprising a polar group-containing copolymer obtained by copolymerizing a conjugated diene compound and a polar group-containing vinyl compound, and a modified natural rubber having a phosphorus content of 200 ppm or less,
The polar group-containing vinyl compound has a polymerizable unsaturated bond and a polar group, and has at least one carbon atom forming the polymerizable unsaturated bond and a carbon atom to which the polar group is bonded. A compound bonded through the carbon atom of
The polar group is a group represented by a hydroxyl group, —NR ₂ , or —Si (OR) _k (R) _3-k (where R represents hydrogen or a hydrocarbon group having 1 to 8 carbon atoms). They may be the same or different, k represents an integer of 1, 2 or 3.
The rubber composition for tires, wherein the cis content of the double bond portion of the conjugated diene compound is 80 mol% or more. The polar group-containing vinyl compound has the following general formula (I):

(In Formula (I), R ¹ represents hydrogen, a vinyl group, or an aliphatic hydrocarbon group having 1 to 3 carbon atoms, and may be the same or different. R ² represents hydrogen or one carbon atom. Represents an aliphatic hydrocarbon group having ˜3, which may be the same or different, R ³ represents hydrogen or an aliphatic or alicyclic hydrocarbon group having 1 to 8 carbon atoms, X is Represents a group represented by a hydroxyl group, the —NR ₂ , or the —Si (OR) _k (R) _{3 —k} , and n represents an integer of ^{1 to} 10. The R ¹ , R ² , R ³ , The carbon atom to which R ² is bonded and the carbon atom to which R ³ is bonded may be bonded to each other to form a ring structure.)
The tire rubber composition according to claim 1, wherein in a compound represented by. The polar group-containing copolymer has a weight average molecular weight of 1.0 × 10 ^{3 to} 2.0 × 10 ⁶ and a content of the polar group-containing vinyl compound of 0.03 to 40% by mass. Item 3. A rubber composition for tires according to item 1 or 2 . The tire rubber composition according to any one of claims 1 to 3 , wherein the conjugated diene compound is 1,3-butadiene and / or isoprene. Before the polar group-containing copolymer is copolymerized, the polar group-containing vinyl compound and the following general formula (II);
M (R ⁴ ) _m (II)
(In formula (II), M represents aluminum, boron, silicon, or titanium. R ⁴ represents an aliphatic or alicyclic hydrocarbon group having 1 to 8 carbon atoms, an aliphatic or aliphatic group having 1 to 8 carbon atoms. A cyclic alkoxy group or halogens, which may be the same or different, m represents an integer of 3 or 4)
The tire rubber composition according to any one of claims 1 to 4 , which is obtained by reacting the compound represented by formula (I) and then copolymerizing the obtained reaction product and the conjugated diene compound. object. The tire rubber composition according to any one of claims 1 to 5 , wherein the modified natural rubber has a nitrogen content of 0.3 mass% or less. The rubber composition for tires according to any one of claims 1 to 6 , wherein the modified natural rubber has a gel content measured as a toluene insoluble content of 20% by mass or less. The tire rubber composition according to any one of claims 1 to 7 , wherein the modified natural rubber is obtained by saponifying natural rubber latex. Total rubber component in 100% by mass, the a 5 to 60% by weight content of the polar group-containing copolymer of claim 1-8 Goyu amount of the modified natural rubber is 40 to 95 wt% The rubber composition for tires in any one. The tire rubber composition according to any one of claims 1 to 9 , comprising 5 to 150 parts by mass of carbon black with respect to 100 parts by mass of all rubber components. The tire rubber composition according to any one of claims 1 to 10, wherein a cis content of a double bond in the conjugated diene compound unit in the polar group-containing copolymer is 80 mol% or more. The tire rubber composition according to any one of claims 1 to 11, which is used for a tread of a heavy duty tire. The manufacturing method of the rubber composition for tires in any one of Claims 1-12 which does not include the process of masticating natural rubber. Heavy duty tire produced using the rubber composition according to any one of claims 1 to 12.