JP2711347B2 - Block copolymer and rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a block copolymer comprising a high trans-1,4 bond polybutadiene block and a polymaleimide block, and a block copolymer comprising the block copolymer as a main component. The present invention relates to a rubber composition having excellent wear resistance and mechanical properties.

[Conventional technology]

In recent years, as the performance of automobiles has become higher, there has been an increasing demand for rubber materials such as tires to be improved in workability, wear resistance, mechanical properties, and the like.

In order to satisfy these characteristics, high cis-1,4 polybutadiene obtained using a conventional Ziegler-type catalyst, low cis-1,4 polybutadiene obtained using a lithium catalyst, and styrene-butadiene copolymer are used. It was difficult with polybutadiene or styrene-butadiene copolymer obtained by coalescence and emulsion polymerization.

On the other hand, in addition to the above-mentioned polymers, poly-butadiene and styrene-butadiene copolymer having a high trans-1,4 bond are known.

For example, Japanese Patent Publication No. 52-48910, Japanese Patent Publication No. 62-21002 and Japanese Patent Publication No. 62-35401 disclose that when a polybutadiene having a trans-1,4 bond content of 70% or more is used, processability is increased. It is disclosed to improve.

However, according to these techniques, there is a problem that preparation of a catalyst for producing polybutadiene is complicated.

JP-A-57-5706 and JP-A-57-157409 to JP-A-57-157411 disclose high trans-1,4 bond polybutadiene by adding a low molecular weight component during polymerization. Although a method for improving workability is disclosed, it is difficult to achieve both mechanical properties and wear resistance and workability.

On the other hand, Japanese Patent Application Laid-Open No. 1-96233 discloses a rubber composition for tires using a high trans-1,4-bond polybutadiene modified with an imide compound. Although this method improves wear resistance, heat generation properties, and mechanical properties, compatibility with workability is still insufficient.

[Problems to be solved by the invention]

The present invention has been made against the background of the above-mentioned conventional technical problems, and comprises a polybutadiene block and a polymaleimide block, which are particularly effective for tires and have a large effect of improving the breaking strength of the obtained vulcanizate and abrasion resistance. An object of the present invention is to provide a block copolymer and a rubber composition containing the copolymer as a main component.

[Means for solving the problem]

The present invention comprises a polybutadiene block (A) having a trans-1,4 bond content of 70 to 90% and a vinyl bond content of 2 to 10%, and a poly-N-substituted maleimide block (B). A copolymer having a number average molecular weight of 50,000 to 1,000,000 (hereinafter referred to as "block copolymer (I)") containing at least 50% by weight of ).

Further, the present invention provides a rubber composition wherein the weight ratio of the raw rubber containing the block copolymer (I) as a main component to the natural rubber and / or the polyisoprene polymer is 100 to 20/0 to 80. The present invention provides a rubber composition containing 0 to 80 parts by weight of process oil per part.

The block copolymer (I) of the present invention comprises a polymaleimide block (B) at the end of a polybutadiene block (A).
Is a novel block copolymer bonded.

That is, the trans-1,4 bond content of the polybutadiene block (A) of the block copolymer (I) is 70 to 90%,
It is preferably 75 to 87%, the vinyl bond content is 2 to 10%, preferably 4 to 9%. If the trans-1,4 bond is less than 70%, the tensile strength and abrasion resistance are poor, while it exceeds 90%. When the vinyl bond content is less than 2%, it is difficult to produce the resin. On the other hand, when it exceeds 10%, the tensile strength and abrasion resistance are poor.

The proportion of the polybutadiene block (A) in the block copolymer (I) is at least 50% by weight, preferably 70% by weight or more, more preferably 80 to 99% by weight. The content of the polymaleimide block (B) becomes excessively large and becomes resinous, and the physical properties of the obtained vulcanized rubber deteriorate.

Furthermore, the average number of chains of the poly-N-substituted maleimide block in the block copolymer (I) is 3 or more, preferably 5 or more, and if the average number of chains is less than 3, affinity with carbon black is obtained. Is low.

Further, the molecular weight of the block copolymer (I) of the present invention is such that the number average molecular weight in terms of polystyrene is usually 5
Ten thousand to one million, preferably 100,000 to 800,000, if less than 50,000, the tensile strength, abrasion resistance, rebound resilience, and heat generation of the vulcanized rubber are inferior. This is not preferable because the torque is excessively applied during kneading in a humidifier or in a banbury, or the compound is heated to a high temperature to cause deterioration, and the dispersion of carbon black is poor and the physical properties of the vulcanized rubber are inferior.

The block copolymer (I) of the present invention has a Mooney viscosity (ML) particularly when used as an industrial rubber product.
_{1 + 4} , 100 ° C.) is usually in the range of 20 to 200, preferably 30 to 160, and for the same reason as the number average molecular weight, if it is less than 20, the physical properties of the vulcanized rubber are inferior, while one exceeds 200 And the processing life is inferior.

The block copolymer (I) of the present invention is obtained by first polymerizing a conjugated diene containing 1,3-butadiene as a main component in an inert organic solvent using a specific catalyst system to obtain a high trans-1,4 bond. By reacting the N-substituted maleimide with the block polymer immediately after polymerization in this way, and bonding the polymaleimide block of a specific chain, rebound resilience, abrasion resistance, and low heat generation And various properties such as mechanical properties.

For example, first, the block copolymer (I) of the present invention is disclosed in JP-A-1-96233, JP-B-52-30543,
57-34843, JP-B-59-17724, JP-A-51-
U.S. Pat.
Polymerizes butadiene.

Examples of the catalyst system include (a) a barium compound (hereinafter referred to as “component (a)”), (b) an organoaluminum compound (hereinafter referred to as “(b) component”), and (c) an organomagnesium compound (hereinafter referred to as “(( a) a catalyst composition comprising (d) an organolithium alkoxide compound and / or an organolithium amide compound (hereinafter, referred to as “component (d)”);
A catalyst composition comprising the component (b), the component (c), and the (e) alcohol and / or tertiary diamine compound (hereinafter, referred to as “component (e)”) can be exemplified.

First, barium compounds used as the component (a) include barium dimethoxide, barium diethoxide, barium diisopropoxide, barium di n-butoxide, barium di sec-butoxide, and barium di-t-oxide.
Butoxide, barium di (1,1-dimethylpropoxide), barium di (1,2-dimethylpropoxide), barium di (1,1-dimethylbutoxide), barium di (1,1-dimethylpentoxide), barium di (2-ethyl) Hexanoxide), barium di (1-methylheptoxide), barium diphenoxide, barium di (p-
Methylphenoxide), barium di (p-butylphenoxide), barium di (o-methylphenoxide), barium di (p-octylphenoxide), barium di (p-nonylphenoxide), barium di (p-dodecylphenoxide), barium di (α-naphthoxide) ,
Barium di (β-naphthoxide), barium (o-methoxyphenoxide), barium di (m-methoxyphenoxide), barium di (p-methoxyphenoxide),
Organic barium compounds such as barium (o-ethoxyphenoxide) and barium di (4-methoxy-1-naphthoxide) can be mentioned.

Further, (a) the barium compound may be an alkoxide group or a phenoxide group of 0.1 to 0.5 per barium atom.
A partial hydrolyzate in which the equivalent is substituted with a hydroxy group is also used.

Specific examples of the organoaluminum compound as the component (b) include trimethylaluminum, triethylaluminum, tripropylaluminum, tributylaluminum, tributylaluminum, bentyldiethylaluminum, 2-methylbenzyl-diethylaluminum,
Dicyclohexylethyl aluminum, tripentyl aluminum, trihexyl aluminum, trioctyl aluminum, tri (2-ethylhexyl) aluminum, tricyclohexyl aluminum, tricyclopentyl aluminum, tri (2,2,4-trimethylpentyl) aluminum, tridodecyl aluminum, tridodecyl aluminum (2-methylpentyl) aluminum, diisobutylaluminum hydride, diethylaluminum hydride, dipropylaluminum hydride, ethylaluminum dihydride, propylaluminum dihydride, isobutylaluminum dihydride, and the like are preferable. Trimethyl aluminum, triethyl aluminum, tributyl aluminum It is.

As the component (b), one type can be used alone, or two or more types can be used in combination.

As the organomagnesium compound as the component (c),
Examples thereof include dialkylmagnesium compounds, diarylmagnesium compounds, and alkylmagnesium halides.Specifically, dimethylmagnesium, dipropylmagnesium, dibutylmagnesium, ethylbutylmagnesium, ethylhexylmagnesium, dihexylmagnesium, dioctylmagnesium, didecylmagnesium, didodecyl Magnesium, dicyclohexyl magnesium, dicyclopentyl magnesium, diphenyl magnesium, ditolyl magnesium, ethyl magnesium bromide, ethyl magnesium chloride, allyl magnesium bromide, propyl magnesium bromide, n-butyl magnesium chloride, phenyl magnesium bromide, phenyl magnesium iodide and the like.

These organomagnesium compounds as the component (c) can be used alone or as a mixture.

The organic lithium alkoxide compound, which is one of the components (d), can be synthesized by reacting an organic lithium compound, lithium metal or lithium hydride with a specific alcohol.

Further, the organic lithium amide compound as the other component of the component (d) can be similarly synthesized by reacting an organic lithium compound, lithium metal or lithium halide with a specific secondary amine.

The lithium compound used for the synthesis of the organic lithium alkoxide compound or the organic lithium amide compound as the component (d) includes ethyl lithium, propyl lithium, butyl lithium, hexyl lithium, 1,4-
Dilithiobutane, a reaction product of butyllithium and divinylbenzene, alkylenedilithium, phenyllithium,
Examples thereof include stilbene dilithium, isopropenylbenzene dilithium, lithium naphthalene, lithium metal, and lithium hydride.

Further, in the synthesis of the component (d), an equivalent of a hydroxyl group of an alcohol which is active hydrogen or a hydrogen atom of a secondary amine is used with respect to a lithium atom of an organic lithium compound, lithium metal or lithium hydride. Reaction in

Specific examples of this alcohol include t-butanol,
sec-butanol, cyclohexanol, octanol, 2-ethylhexanol, p-cresol, m-cresol, nonylphenol, hexylphenol, tetrahydrofurfuryl alcohol, furfuryl alcohol, 3-methyl-tetrahydrofurfuryl alcohol,
4-ethyl-tetrahydrofurfuryl alcohol, oligomers of tetrahydrofurfuryl alcohol, ethylene glycol monophenyl ether, ethylene glycol monobutyl ether, N, N-diethylethanolamine, N, N-dibutylethanolamine, N, N-diphenylethanolamine , N-methyldiethanolamine, N
-Ethyldiethanolamine, N-butyldiethanolamine, N-phenyldiethanolamine, N, N-dimethylpropanolamine, N, N-dibutylpropanolamine, N-methyldipropanolamine, N-ethyldipropanolamine, 1- (2-hydroxy ethyl)
Pyrrolidine, 2-methyl-1- (2-hydroxyethyl) pyrrolidine, 2-methyl-1 (3-hydroxypropyl) pyrrolidine, 1-piperidineethanol, 2-phenyl-1-piperidineethanol, 2-ethyl-1-
Piperidinepropanol, N-β-hydroxyethylmorpholine, 2-ethyl-N-β-hydroxyethylmorpholine, 1-piperazineethanol, 1-piperazinepropanol, N, N′-bis (β-hydroxyethyl) piperazine, N, N '-Bis (γ-hydroxypropyl) piperazine, 2- (β-hydroxyethyl) pyridine,
-(Γ-hydroxypropyl) pyridine and the like, and preferred are tetrahydrofurfuryl alcohol, N, N-dimethylethanolamine, N, N-diethylethanolamine and 1-piperidineethanol.

Specific examples of the secondary amine include diethylamine, dipropylamine, diisopropenylamine, dibutylamine, dihexylamine, diphenylamine,
Ditolylamine, morpholine, piperidine, piperazine, N-methylpiperazine, N-ethylpiperazine, N,
N'-dimethylethylenediamine, N, N, N'-trimethylethylenediamine, N, N'-diethylethylenediamine, N, N, N'-triethylenediamine, N, N-diphenylethylenediamine, N, N-diphenyl-N'- Methyl ethylene diamine and the like can be mentioned.

Next, as the alcohol which is one of the components (e), the above-mentioned various alcohols before the synthesis of the component (d) can be used.

The other tertiary amine of the component (e) includes N, N,
N ', N'-tetraethylethylenediamine, N, N', N'-
Examples include tetrabutylethylenediamine, N, N ', N'-tetraphenylethylenediamine, N, N-diphenyl-N, N'-dimethylethylenediamine, dipiperidinoethane, and the like.

The amount of the catalyst composition used in the present invention is 1,
The amount of the barium compound (a) per mol of 3-butadiene is 0.05 to 1 mmol, preferably 0.1 to 05 mmol in terms of barium atom.

The amount of the components (a) to (e) used is represented by the following ratio per mole of the barium compound as the component (a). That is, the composition (molar ratio) of the catalyst composition used in the present invention is (component (a) / component (b) / component (c)).
Component / (d) component = 1/1 to 10/1 to 10/1 to 5, preferably 1/2 to 7/2 to 7 / 1.2 to 4, more preferably 1/3 to 6 /
3-5 / 1.5-3.

Also, component (a) / component (b) / component (c) / (e)
The components (molar ratio) are from 1/1 to 10/1 to 10/1 to 4, preferably 1 to 10.
/ 3 to 6/3 to 7/1 to 3.

Further, as a catalyst component, the above-mentioned (a)
In addition to the components (d) or (a) to (e),
If necessary, a conjugated diene may be added in an amount of 0.1 to 1 mol of the component (a).
You may use it in the ratio of 05 to 20 mol.

The conjugated diene used for catalyst preparation is isoprene, 1,3-
Butadiene, 1,3-pentadiene and the like are used. Although a conjugated diene as a catalyst component is not essential, the combined use thereof further improves the catalytic activity of the catalyst component.

To prepare the catalyst, for example, the components (a) to (d) dissolved in an inert organic solvent, or (a) to (c),
(E) reacting a component and, if necessary, a conjugated diene. At that time, the order of addition of each component may be arbitrary. These components are mixed and reacted in advance,
Aging is preferred from the viewpoint of improving the polymerization activity and shortening the period of inducing polymerization initiation, but each component of the catalyst may be added directly to the solvent and the monomer during the polymerization.

The polymerization solvent is an inert organic solvent, for example, benzene, toluene, aromatic hydrocarbon solvents such as xylene, n-pentane, n-hexane, aliphatic hydrocarbon solvents such as n-butane, methylcyclopentane, Alicyclic hydrocarbon solvents such as cyclohexane and mixtures thereof can be used.

The polymerization temperature is usually -20 ° C to 150 ° C, preferably 30 ° C.
~ 120 ° C. The polymerization reaction may be a batch type or a continuous type.

The monomer concentration in the solvent is usually 5 to 50% by weight,
Preferably it is 10 to 35% by weight.

Further, in order to produce a copolymer, in order not to deactivate the catalyst system and the polymer of the present invention, oxygen,
Care must be taken to minimize the incorporation of compounds having a deactivating effect such as water or carbon dioxide.

The diene component of the block copolymer (I) of the present invention is 1, 1
In addition to 3-butadiene, isoprene and 2,3-dimethyl-1,
3-butadiene, 1,3-pentadiene, myrcene and the like can also be used in combination.

Further, the block copolymer (I) used in the present invention
Is a vinyl aromatic compound such as styrene, α-methylstyrene, p-methylstyrene, o-methylstyrene, p-butylstyrene, and vinylnaphthalene, in addition to 1,3-butadiene, vinyl pyridine, acrylonitrile, Acrylonitrile, methyl (meth) acrylate, acrylate, and the like can be copolymerized, and a vinyl aromatic compound, particularly styrene, is most preferred.

In the present invention, first, the above-mentioned (a) to (d)
The polybutadiene block can be formed by polymerizing 1,3-butadiene in an inert organic solvent using a component or a catalyst system comprising components (a) to (c) and (e). The polybutadiene block obtained in this way has a trans-1,4
The bond content is 70-90%, preferably 75-87%, and the vinyl bond is 2-10%, preferably 4-9%.

In addition, as a repeating unit of the polybutadiene block (A), a trans-1,4 bond is It is represented by

The block copolymer (I) of the present invention is obtained by reacting an N-substituted maleimide with the terminal of the polybutadiene block thus obtained to form a polymaleimide block having three or more chains.

Examples of the N-substituted maleimide include N-methylmaleimide, N-ethylmaleimide, N-butylmaleimide, N-phenylmaleimide, N-toluylmaleimide, N-naphthylmaleimide and the like.

The N-substituted maleimides may be used alone or in combination of two or more.

The amount of N-substituted maleimide used is 0.5 to 50% by weight of N-substituted maleimide relative to the total amount of monomers, and more preferably depends on the molecular weight of the block copolymer to be produced, and the number of polymaleimide block chains is 3 or more, preferably Is 5
This is the amount of addition that is above.

The repeating unit of the poly (maleimide) block (B) is It is represented by

In addition to the above-mentioned N-substituted maleimide, in order to widen the molecular weight distribution of the obtained block copolymer (I) and reduce the cold flow of raw rubber, a tin halide compound having two or more functionalities or a halogenated compound is used. A metal halide compound such as a silicon compound is added in an amount of 0.5 to 5 based on the halogen atom per 1 g of barium metal atom in the catalyst composition.
It can be added in an equivalent amount, preferably in a range of 0.1 to 1.5 equivalents.

Examples of the metal halide compound include dibutyldichlorotin, diphenyldichlorotin, methyltrichlorotin, butyltrichlorotin, phenyltrichlorotin, tetrachlorotin, and bis (trichlorostannyl).
Examples thereof include ethane, dibutyldichlorosilicon, methyltrichlorosilicon, tetrachlorosilicon, and a tin carboxylate compound, and these compounds can be used alone or in combination.

According to the above method, an AB type, an ABA type, or an ABAB type (where A represents a polybutadiene block (A) and B represents a poly N-substituted maleimide block) A copolymer is obtained.

The polymerization temperature of the polybutadiene block and the N-substituted maleimide is usually 0 to 120 ° C, preferably 50 to 100 ° C.
The polymerization temperature is usually 10 seconds to 50 hours.

After completion of the reaction, steam is blown into the polymer solution to remove the solvent, or a poor solvent such as methanol is added to coagulate the polymer, and then the polymer is dried under a hot roll or under reduced pressure to obtain the block copolymer (I). Obtainable. Further, the block copolymer (I) can also be obtained by directly removing the solvent from the polymer solution under reduced pressure.

Next, the rubber composition of the present invention is prepared by blending the block copolymer (I) of the present invention alone or blended with another synthetic rubber or natural rubber as a raw material rubber, and if necessary, using a process oil to prepare an oil. Then, a usual vulcanized rubber compounding agent such as carbon black as a filler, a vulcanizing agent and a vulcanization accelerator is added.

In this case, in order to exhibit the excellent characteristics of the block copolymer (I) blended in the present invention, the block copolymer (I) is contained in the raw rubber in an amount of 20% by weight or more, preferably 30% by weight or more. % Or more.

Examples of the process oil used for oil extension include, for example, paraffinic, naphthenic, and aromatic types. For applications where tensile strength and abrasion resistance are important, an aromatic type has a rebound resilience. Naphthenic or paraffinic is used in applications where low-temperature characteristics are important, and the amount used is 0 to 80 parts by weight, preferably 20 to 60 parts by weight, based on 100 parts by weight of raw rubber, and 80 parts by weight. If it exceeds 300, the tensile strength and the rebound resilience of the vulcanized rubber are significantly reduced.

Furthermore, the carbon black used is HA
Carbon black such as F, ISAF, SAF, etc., and preferably carbon black having an iodine adsorption amount (IA) of 60 mg / g or more and a dibutyl phthalate oil absorption (DBP) of 80 ml / 100 g or more are used. The used amount of this carbon black is 35 to 100 parts by weight, preferably 40 to 100 parts by weight of the raw rubber.
When the amount is less than 34 parts by weight, the vulcanizate has insufficient tensile strength and abrasion resistance. On the other hand, when the amount exceeds 100 parts by weight, resilience and heat generation are reduced.

Further, as a vulcanizing agent, usually, sulfur is used,
The amount used is 0.1 to 3 parts by weight, preferably 0.5 to 2 parts by weight, based on 100 parts by weight of the raw rubber. If less than 0.1 part by weight, the tensile strength, abrasion resistance and rebound resilience of the vulcanized rubber decrease. ,
On the other hand, if it exceeds 3 parts by weight, it becomes hard and loses rubber elasticity.

Further, as a vulcanization aid and a processing aid, stearic acid is generally used, and the amount of use is 0.5 to 5 parts by weight based on 100 parts by weight of the raw rubber.

Further, the vulcanization accelerator is not particularly limited, but is preferably M (2-mercaptobenzothiazole), DM (dibenzothiazyl disulfide), CZ (N
-Cyclohexyl-2-benzothiazylsulfenamide) and the like, and the amount of the thiazole-based vulcanization accelerator is 0.1 to 5 parts by weight based on 100 parts by weight of the raw rubber.
Parts by weight, preferably 0.2 to 3 parts by weight.

In the rubber composition of the present invention, if necessary, fillers other than carbon black, such as silica, calcium carbonate, and titanium oxide, and additives such as zinc oxide, an antioxidant, and an antiozonant can be blended. .

The rubber composition of the present invention is obtained by kneading using a kneading machine such as a roll and an internal mixer, and after molding, using vulcanization, tire red, bander tread, car curse, sidewall, beet. In addition to tire applications such as parts, hoses, belts, shoe soles, window frames,
Although it can be used for applications such as sealing materials, vibration-proof rubbers, and other industrial products, it is particularly suitably used as a rubber for tire treads.

[Action]

Although the reason why the vulcanizate of the copolymer (I) comprising a high trans-bonded polybutadiene block and a polymaleimide block of the present invention is excellent in mechanical properties and abrasion resistance is not necessarily clear, many polymaleimide block chains are included. This is considered to enhance the interaction with carbon black, and further enhance the interaction with carbon black by breaking the maleimide group in the kneading process.

In addition, since the polybutadiene block is high in trans and low in vinyl, it is estimated that when the molecular chain is highly elongated, there is hysteresis due to the stretched crystal.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof.

In the examples, parts and% are unless otherwise specified.
It means parts by weight and% by weight.

Various measurements in the examples were based on the following methods.

The ratio between the polybutadiene block and the polymaleimide block was determined by ¹ H-NMR analysis, or an infrared analysis method after preparing a calibration curve in advance.

The microstructure of the polymer was determined by an infrared absorption spectrum method (Morello method).

The molecular weight of the polymer was determined by GPC analysis, and the average molecular weight was calculated in terms of polystyrene.

Mooney viscosity was measured at a preheating time of 1 minute, a measurement time of 4 minutes, and a temperature of 100 ° C. (According to JIS K6300).

The physical properties of the vulcanized product were measured using a raw rubber, kneading and compounding with a 230 cc Brabender and a 6-inch roll according to the following formulation, and then vulcanizing at 145 ° C for a predetermined time. A measurement was made.

Formulation (Parts) Polymer 100 Carbon black (HAF) 70 Process oil Variable amount Stearic acid 2 Zinc white 3 Antioxidant (810NA) ^{* 11} (TP) ^{* 2} 0.8 Vulcanization accelerator (MSA) ^{* 31} Sulfur 1.5 * 1) N-phenyl-N'-isopropyl-p-phenylenediamine * 2) Sodium-dibutyldiotica-bamate * 3) N-oxydiethylene-2-benzothiazolesulfenamide Tensile properties were measured according to JIS K6301. .

The rebound resilience is measured using a Dunlop trypsometer.
Rebound resilience at 50 ° C and 80 ° C was used.

The internal loss (tan δ) was measured using a dynamic spectrometer manufactured by Reomex of the United States.
%, Frequency 10 Hz, 50 ° C. Δtanδ is
Using the same apparatus, the distortion was obtained by varying the amount of distortion.

The Lambourn abrasion index was measured using a Lambourn abrasion tester with a load of 4.5 kg, a slip rate of 10%, and a wear of 20 m.
g / min and the measurement temperature was room temperature. The larger the index,
The wear resistance is good.

Example 1 Preparation of Catalyst Component (a) -1 Under a dry nitrogen atmosphere, 100 ml of cyclohexane was placed in a 300 ml eggplant-shaped flask, and 10 ml of a 1.0 mol / triethylaluminum cyclohexane solution was added.

Next, while cooling in an ice bath, 6.3 ml of a 1.6 mol / n-butyllithium n-hexane solution was added dropwise and left for 30 minutes. The resulting white powder was washed with cyclohexane and dried.

The ratio of lithium atoms to aluminum atoms in the obtained powder was approximately 1: 1.

Preparation of catalyst component (b) -1 Using the same apparatus as above, into 100 ml of cyclohexane
10 ml of a 1.0 mol / nonylphenoxybarium solution in toluene was added.

Next, while cooling in an ice bath, 40 ml of a 1.0 mol / triethylaluminum cyclohexane solution was added dropwise. After the addition, the mixture was refluxed at 80 ° C. for 1 hour. The solution was left at −15 ° C. for 24 hours to crystallize. The ratio of barium atoms to aluminum atoms in the obtained crystal was approximately 1: 2.

Preparation of Catalyst Component (c) -1 Using the same apparatus as above, a 1.6 mol / n-butyllithium solution was added dropwise to a 1.0 mol / cyclohexane solution of tetrahydrofurfuryl alcohol while cooling in an ice bath. Thereafter, the concentration was adjusted to 0.5 mol / lithium tetrahydrofurfuroxyl lithium.

Synthesis of copolymer (I) (polybutaene-borimaleimide block copolymer) In a pressure-resistant bottle having an inner volume of 300 ml, cyclohexane 120 g, 1,3
-30 g of butadiene were added.

Next, the catalyst component (b) -1 was dissolved in a cyclohexane solution while heating to 70 ° C., and 0.27 mmol was added. Subsequently, the catalyst component (a) -1 was similarly added in an amount of 0.81 mmol.

Finally, 0.54 mmol of catalyst component (c) -1 was added,
Polymerization was performed at 70 ° C. for 90 minutes.

Subsequently, 6 g of N-phenylmaleimide was added, and
Polymerization was performed for 0 minutes.

After completion of the reaction, di-t-butyl-p-
0.7 g of cresol is added to 100 g in terms of solid rubber,
After coagulation with methanol, it was dried at 40 ° C. under reduced pressure.

 The yield of the polymer was 92%.

The microstructure of the polybutadiene block of the obtained polymer was such that the trans-1,4 bond content was 86%, the vinyl bond content was 4%, and the cis-1,4 bond content was 10%.

As an analytical sample, the obtained polymer was reprecipitated and purified with toluene / methanol. FIG. 1 shows the infrared absorption spectrum of the obtained polymer.

As apparent from FIG. 1, a large absorption peak peculiar to the maleimide group appears around 1700 cm ⁻¹ .

FIG. 2 shows a ¹ H-NMR chart of the obtained polymer. The addition amount of N-phenylmaleimide determined from FIG. 2 was 5.4 mol%, and the block efficiency of the added N-phenylmaleimide was about 77%.

FIG. 3 shows a GPC chart of the polymer. As is clear from FIG. 3, the molecular weight distribution determined by the differential refractometer and the molecular weight determined by ultraviolet rays (UV, 254 nm) are as follows.
It can be seen that the absorption intensity appears corresponding to the molecular weight, and that the absorption intensity of the ultraviolet absorption spectrum increases as the molecular weight decreases.

Further, the number average molecular weight (Mn) of the obtained polymer was 6.3.
10,000, the weight average molecular weight (Mw) is 114,000, and Mw / Mn is 1.8
And a block copolymer having a relatively narrow molecular weight distribution.

Furthermore, when the average number of chains of poly N-phenylmaleimide was determined from ¹ H-NMR analysis and Mn of GPC analysis, 56.3
Was individual.

Comparative Example 1 In the same apparatus as in Example 1, only 1,3-butadiene was polymerized in the same manner as in Example 1.

 The polymer yield was 98%.

The microstructure of this polybutadiene is trans-1,4
The bond content was 86%, the vinyl bond content was 4%, and the cis-1,4 bond content was 10%.

FIG. 4 shows an infrared absorption spectrum of this polybutadiene, and FIG. 5 shows a GPC chart thereof.

It can be seen that both FIG. 4 and FIG. 5 are greatly different from those of the block copolymer comprising the polybutadiene block and the poly N-phenylmaleimide block obtained in Example 1.

Example 2 Polybutadiene-polyN was prepared in the same manner as in Example 1 except that the amount of N-phenylmaleimide added was 3.0 g.
-The polymerization of the phenylmaleimide block copolymer was carried out. The polymer yield was 95%.

The microstructure of the polybutadiene portion was as follows: the trans-1,4 bond content was 87%, the vinyl bond content was 4%, and the cis-
The 1,4 bond content was 9%.

The addition amount of N-phenylmaleimide obtained from ¹ H-NMR analysis was 3.1 mol%, and the block efficiency was about 93%.

According to GPC analysis, the number average molecular weight (Mn) was 6.8.
10,000, the weight average molecular weight (Mw) was 112,000, and Mw / Mn was 1.6.

Furthermore, the average number of chains of poly N-phenylmaleimide was 36.5.

Example 3 A dry reaction vessel having an inner volume of 5 equipped with a stirrer and a jacket was replaced with nitrogen, and 2,000 g of cyclohexane and 500 g of 1,3-butadiene which had been purified and dried in advance were charged.

In a separate vessel, 1.68 mmol of nonylphenoxybarium and 3.36 mmol of triethylaluminum were aged at 80 ° C. for 1 hour to synthesize an ate complex, and this solution was added to the reaction vessel.

Separately, 5.05 mmol of n-butyllithium and 5.05 mmol of triethylaluminum were aged at 80 ° C. for 5 minutes to synthesize an ate complex, and this solution was added to the reaction vessel, followed by 3.36 mmol of diethylaminoethoxylithium.
The reaction mixture was polymerized at 70 ° C. for 120 minutes.

Subsequently, 5.0 g of N-phenylmaleimide was added and 70
Polymerization was further performed at 180 ° C. for 180 minutes.

 The polymer yield was 97%.

The microstructure of the polybutadiene block of this polymer was 84% trans-1,4 bond content, 6% vinyl bond content, and 10% cis-1,4 bond content.

The block amount of N-phenylmaleimide determined by infrared analysis was 0.8%.

Further, a part of the polymerization solution was taken out before adding N-phenylmaleimide and subjected to GPC analysis. As a result, the number average molecular weight (Mn) of the polybutadiene block was 191,000, the weight average molecular weight (Mw) was 298,000, and Mw / Mn was 1.6.

The Mooney viscosity of this product was 42. The average number of chains of poly N-phenylmaleimide in the obtained block copolymer was determined by GPC analysis and the content of N-phenylmaleimide. As a result, it was 8.8. First polymerization result
It is shown in the table.

Comparative Example 2 Polymerization was carried out in the same manner as in Example 3 except that the amount of N-phenylmaleimide added in Example 3 was reduced from 5.0 g to 0.6 g.

 Table 1 shows the results of the polymerization and the results of the analysis.

Example 4 N-phenylmaleimide was used in place of N-phenylmaleimide of Example 3, and polybutadiene-polyN-
A methylmaleimide block copolymer was obtained. Table 1 shows the results of the polymerization.

Example 5 A polybutadiene-polyN-ethylmaleimide block copolymer was obtained by using N-ethylmaleimide instead of N-phenylmaleimide in Example 3. Table 1 shows the results of the polymerization.

Examples 6 to 9 The polymers A to C obtained in Examples 3 to 5 were vulcanized in accordance with the above blending recipe.

 The vulcanization properties are shown in Table 2.

Comparative Examples 3 to 7 In Comparative Examples 3 and 5, the polymer α of Comparative Example 2 was replaced with Comparative Example 4.
Is high cis-1,4 polybutadiene rubber BR31 manufactured by Nippon Synthetic Rubber Co., Ltd., Comparative Example 6 is high cis-1,4 polybutadiene rubber BR21 manufactured by Japan Synthetic Rubber Co., Ltd., and Comparative Example 7 is ,
A high cis-1,4 polybutadiene rubber manufactured by Nippon Synthetic Rubber Co., Ltd., BR31 was used, and a process oil was further compounded, and vulcanization was performed according to the above-mentioned compounding recipe.

 The vulcanization properties are shown in Table 2.

As is clear from Table 2, the copolymer (I) of the present invention
(Polybutadiene-polymaleimide block copolymer)
It is presumed that the dispersion of carbon black is good because Δtanδ is small. The reason why the dispersion of carbon black is improved is that, when comparing the block copolymer of the present invention having a long maleimide chain with cis-1,4-polybutadiene containing no maleimide of a polymer having a short chain, the order of the chain is long. Since Δtan δ is small, it is considered that the polymaleimide chain greatly contributes. In other words, it can be considered that the polymaleimide block having a strong interaction with the carbon black improves the dispersion of the carbon black and improves the abrasion resistance.

[Effects of the Invention] The block copolymer of the present invention is a block copolymer of polymaleimide having high crystallinity and high interaction between polybutadiene having high trans-1,4 bond and carbon black, and the block copolymer. A vulcanizate obtained from a rubber composition using a polymer has excellent mechanical properties and abrasion resistance, and is suitable for use in tires, particularly for use in tires in which grip is emphasized.

[Brief description of the drawings]

FIG. 1 shows the polybutadiene-polyN- obtained in Example 1.
FIG. 2 shows a ¹ H-NMR chart of the phenylmaleimide block copolymer, and FIG. 3 shows a GPC chart of the phenylmaleimide block copolymer. FIG. 4 is an infrared absorption spectrum of the polybutadiene obtained in Comparative Example 1, and FIG. 5 is a GPC chart thereof.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Takashi Imamura 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd. (72) Inventor Shunji Araki 3-5-5 Ogawa Higashicho, Kodaira City, Tokyo ( 56) References JP-A-1-230612 (JP, A)

Claims (2)

(57) [Claims] 1. A block (A) comprising a polybutadiene block (A) having a trans-1,4 bond content of 70 to 90% and a vinyl bond content of 2 to 10% and a poly-N-substituted maleimide block (B). ), And having a number average molecular weight of 50,000 to 1,000,000, wherein the block (B) has an average number of monomer chains of at least 3 or more. 2. A rubber component 1 wherein the weight ratio of the raw rubber mainly comprising the block copolymer according to claim 1 to natural rubber and / or polyisoprene polymer is 100-20 / 0-80.
A rubber composition containing 0 to 80 parts by weight of a process oil based on 00 parts by weight.