JP2002179729A - Polymer and rubber composition using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polymer with a special structure having an amide bond useful for improvement of both dry-grip characteristic and wet-skid resistance without affecting break resistance or abrasion resistance, and to obtain a rubber composition using the polymer. SOLUTION: This polymer contains at least one amide bond in the molecule expressed by at least one selected from the group consisting of -NH-C(=O)-, >NC(=O)N< and >NC(=O)-O-, and the weight average molecular weight per one of the amide bond is 500 to 100,000. The rubber composition is formulated with the polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer having an amide bond and a rubber composition using the same. More specifically, the use of the polymer enhances hysteresis loss and improves grip characteristics. The present invention relates to a rubber composition having both improved fracture resistance.

[0002]

2. Description of the Related Art In recent years, safety and low fuel consumption have been demanded for automobiles, and as materials for tires, in particular, tire treads for passenger cars, performances such as dry grip characteristics, wet skid resistance and durability have been developed. Is very important and further improvement is demanded. By the way, it is generally known that in order to increase the hysteresis loss of a rubber composition, a relatively large amount of a softening agent may be added, but on the other hand, the fracture resistance of the rubber composition is inevitably reduced. . Therefore, conventionally, many techniques for blending a low molecular weight polymer (liquid polymer) having an average molecular weight of several thousands to tens of thousands have been developed. As these compounding agents, for example, liquid SBR having good compatibility with rubber, hydrogenated (hydrogenated) liquid SBR, liquid BR, styrene-isobutylene random copolymer, and the like are considered to be useful. Especially liquid SBR, hydrogenated liquid SBR
As compared to general-purpose softeners such as aromatic oils, high hysteresis loss and high fracture resistance can be obtained, so it is preferably used for high-performance tires that require both high grip characteristics and durability. it can.

[0003] However, for further improvement of both of these properties, for example, there is a limit only by changing the microstructure or molecular weight, and further improvement has been difficult. Conventionally, the tan of the rubber composition accompanying the temperature rise due to running has been increased.
As a compounding agent for suppressing the decrease in δ and increasing the hysteresis loss, a nitrogen-containing low-molecular compound having a urea structure or an amide structure is known as a so-called “high loss agent”, and is used as a protonic acid (counter acid). In addition, a method of improving hysteresis loss at a relatively high temperature and improving dry grip is mainly used by compounding the rubber with rubber. However, also in this case, in order to improve the high loss property of the rubber composition, it is necessary to mix the above-mentioned high loss agent in a relatively large amount, and as a result, the fracture resistance of the rubber composition is reduced. There was a problem that it was unavoidable.

[0004]

SUMMARY OF THE INVENTION The present invention provides an amide which is useful for improving both dry grip characteristics and wet skid resistance without adversely affecting the fracture resistance and abrasion resistance under such circumstances. An object of the present invention is to provide a polymer having a specific structure having a bond and a rubber composition using the polymer.

[0005]

Means for Solving the Problems The present inventor has focused on the fact that conventionally used liquid polymers have a relatively large number of molecular terminals per fixed weight, and to efficiently introduce a specific functional group into the molecular terminals. It was found that high hysteresis loss property was improved by the method, and the present invention was completed. That is, the present invention relates to a compound represented by —NH—C (＝ O) —,> N
Having at least one amide bond represented by at least one selected from the group consisting of C (= O) N <and> NC (= O) -O-, and a weight average molecular weight per one amide bond Is from 500 to 100,000. Also, the present invention
100 parts by weight of a rubber component and -NH-C (= O) in the molecule
-,> NC (= O) N <and> NC (= O) -O- having at least one amide bond represented by at least one selected from the group consisting of: The present invention also provides a rubber composition comprising 5 to 250 parts by weight of a polymer having a weight average molecular weight of 500 to 100,000.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The polymer according to the present invention comprises at least one of —NH—C (＝ O) —,> NC (＝ O) N <or> NC (＝ O) —O— in the molecule. It contains a kind of amide bond. Also preferably, R ₁ —NH—C (＝ O) —, R ₁ —NH—C (=
O) -NR ₂ -, or _{R 1 -NH-C (= O} ) -O-
(However, R ₁ and R ₂ are each an alkyl group having 1 to 30 carbon atoms, an aryl group, an aralkyl group, an alkylaryl group, or a hydrogen atom.)

As such a polymer, a modified polymer obtained by modifying a terminal group of a homopolymer or a copolymer of a conjugated diene, or a terminal group of a copolymer of a conjugated diene and a monovinyl aromatic hydrocarbon is used. A modified polymer obtained by modifying is preferred. That is, one or more conjugated dienes or a conjugated diene and a monovinyl aromatic hydrocarbon are subjected to solution polymerization in a hydrocarbon solvent using a lithium-based initiator in a hydrocarbon solvent. (Anionic group) by reacting with a specific nitrogen-containing modifier. Here, the conjugated diene as a monomer component is, for example, 1,3-butadiene; isoprene;
3-pentadiene; 2,3-dimethylbutadiene; 2-
Phenyl-1,3-butadiene and the like. These may be used alone or as a mixture of two or more,
Further, they may be used by copolymerizing with other dienes such as 1,3-hexadiene. Among them, 1,3-butadiene is preferable.

The monovinyl aromatic hydrocarbon copolymerized with the conjugated diene includes styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene; Examples include monomers such as 4,6-trimethylstyrene, and among them, styrene is preferable. Examples of the hydrocarbon solvent include aliphatic hydrocarbons such as pentane, hexane and octane, alicyclic hydrocarbons such as methylcyclopentane and cyclohexane, and aromatic hydrocarbons such as benzene and xylene. Examples of the lithium initiator include normal butyl lithium; sec-butyl lithium; alkyl lithium such as 1,4-dilithiobutane;
Organic lithium amides such as N-methylbenzyllithium amide; dioctyllithium amide and the like are used.
In particular, when a multilithium-based initiator is used, both ends of the polymer can be modified, so that the modification ratio is greatly improved. For example, dilithium initiator can be obtained by preconditioning secondary butyllithium and diisopropenylbenzene under appropriate conditions. It is known that both lithium in one molecule are polymerization active,
Since it has a living property even in the latter stage of polymerization, both terminals of the polymer can be modified.

Next, as a method of reacting with the terminal anion group of the living polymer, for example, a method of treating with an isocyanate, a method of reacting with an imine compound and then treating with an isocyanate, and the like are available. Here, as the isocyanate compound, for example, phenyl isocyanate;
4,4'-methylenebisphenyl isocyanate (MD
I); 2,4-toluylene diisocyanate (2,4-
TDI); 2,6 Toluylene diisocyanate (2,6
-TDI), crude methylene diisocyanate (crude MDI), diphenylmethane diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, p-phenylene diisocyanate, xylylene diisocyanate; benzene-1,2,4- Aromatic isocyanates such as triisocyanate; naphthalene-1,2,5,7-tetraisocyanate; naphthalene-1,3,7-triisocyanate; hexamethylene diisocyanate; methylcyclohexane diisocyanate; Aliphatic isocyanates and the like can be mentioned.

The imine compound used in the case of treating with an isocyanate after reacting with the imine compound includes, for example, ethaneimine, benzylimine, acetoneimine, acetophenoneimine, benzylideneaniline, benzylideneethylamine; benzamidine, acetamidine, -Phenylbenzamidine, 1-methylbenzamidine, 1-phenylacetamidine, 1-benzoylbenzamidine, 1-acetylbenzamidine, 1-benzoylacetamidine, N-amidinobenzamide, N-amidinoacetamide, N- (N- Amidines such as phenylamidino) benzamide, N- (N-phenylamidino) acetamide, N- (N-phenylamidino) stearinamide, N- (N-methylamidino) benzamide Compounds; benzohydrazide imine, acetohydrazide imine, 2-phenyl-benzo hydrazide imine, 2-methylbenzoyl hydrazide imine, 2
-Phenylacetohydrazidoimine, 2-benzoylbenzohydrazidoimine, 2-acetylbenzohydrazidoimine, 2-benzoylacetohydrazidoimine, 2-
Hydrazidoimine compounds such as amidinobenzohydrazidoimine are exemplified. Among the above,> C = NH-
Compounds having an imino group of the structure are preferred.

The polymer having an amide bond in the present invention is required to have a weight average molecular weight per one amide bond in the molecule of 500 to 100,000.
If the weight average molecular weight per unit amide bond is less than 500, it is difficult to obtain sufficient fracture resistance and abrasion resistance. If it exceeds 100,000, the concentration of the amide bond number becomes too small, resulting in dry grip. It is difficult to achieve both characteristics and wet skid properties. Here, the number of amide bonds can be measured by a ¹³ C-NMR method. The weight average molecular weight per amide bond is 3
It is preferably in the range of 000 to 50,000, more preferably 5,000 to 30,000. By selecting this range, dry grip characteristics and wet skid properties are further improved.

Further, the microstructure of the above polymer is such that the amount of bound styrene is 10 to 60% by weight and the amount of vinyl
%. In the rubber composition of the present invention in which the polymer having the amide bond is blended, the loss tangent (tan δ) can be improved in a wide temperature range without adversely affecting the fracture resistance and wear resistance. For example, compared with the case of the conventional unmodified liquid polymer compound, 30 ° C.
The tan δ at 50 ° C. increases by 10 to 20%,
A rubber composition in which tan δ at 0 ° C. has increased by 5 to 10% can be easily obtained.

In the rubber composition of the present invention, the polymer is used in an amount of 5 to 250 parts by weight, preferably 20 to 150 parts by weight, more preferably 3 to 100 parts by weight of the rubber component.
0 to 120 parts by weight are blended. If less than 5 parts by weight, tan
The effect of improving δ is not sufficient, and if it exceeds 250 parts by weight, the destruction resistance and wear resistance may be adversely affected. The rubber component is preferably a diene rubber, for example, natural rubber; emulsion-polymerized or solution-polymerized styrene-butadiene copolymer rubber (SBR), polyisoprene rubber (I
R), polybutadiene (BR), ethylene-propylene-diene copolymer rubber (EPDM), butyl rubber (I
R) and the like. These diene-based synthetic rubbers may be modified with a polyfunctional modifier such as tin tetrachloride and have a branched structure.
Alternatively, any blend of rubber is used. Among these diene rubbers, a styrene-butadiene copolymer rubber is particularly preferred.

The rubber composition of the present invention preferably contains a filler, and any filler can be used as long as it can be used in general rubber compositions. Reinforcing fillers made of carbon black and / or silica are preferred. There is no particular limitation on the carbon black, for example, FEF, SRF, HAF,
ISAF, SAF, etc. are used, but the iodine adsorption amount (I
Carbon black having A) of 60 mg / g or more and dibutyl phthalate oil absorption (DBP) of 80 ml / 100 g or more is preferred. By using carbon black, the effect of improving grip characteristics and breaking characteristics is increased, but HAF, ISAF, and SAF, which are excellent in wear resistance, are particularly preferable. The silica is not particularly limited, and examples thereof include wet silica (hydrous silicic acid), dry silica (silicic anhydride), calcium silicate, aluminum silicate, and the like. Wet silica, which has the most remarkable effect of achieving low rolling resistance, is preferred.

The filler can be either carbon black alone or silica alone. In this case, carbon black or silica is usually blended in an amount of 10 to 250 parts by weight with respect to 100 parts by weight of the rubber component. From the fact that the reinforcing property and the effect of improving various physical properties are high.
~ 150 parts by weight are preferred. If the amount is less than 10 parts by weight, the effect of improving the breaking characteristics and the like may not be sufficient, and if it exceeds 250 parts by weight, the processability of the rubber composition may be poor. In the rubber composition of the present invention, when silica is used as a filler, a silane coupling agent can be used at the time of compounding in order to further improve the reinforcing property. Examples of the silane coupling agent include bis ( 3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, bis (2-
Triethoxysilylethyl) tetrasulfide and the like are preferred.

Since the polymer used in the present invention has a functional group having a high affinity for silica in its molecule, even if the amount of the silane coupling agent to be added is reduced below the usual amount. A rubber composition having the same physical properties can be obtained, and the kneading workability can be improved. The preferred compounding amount varies depending on the type of the silane coupling agent, the compounding amount of silica, etc., but from the viewpoint of improving the reinforcing property, 1 to 20% by weight, preferably 5 to 15% by weight of the silica compounding amount.
It is.

Further, a vulcanizing agent, a vulcanization accelerator, a process oil and the like may be added to the rubber composition of the present invention. Examples of the vulcanizing agent include sulfur, and the compounding amount thereof is preferably 0.1 to 10 parts by weight, more preferably 1 to 5 parts by weight, as the sulfur content based on 100 parts by weight of the rubber component.
If it is less than 0.1 part by weight, the vulcanized rubber has a breaking strength,
It is not preferable that the low heat build-up is reduced, and if the amount exceeds 10 parts by weight, the rubber elasticity is greatly reduced. As the vulcanization accelerator,
Although not particularly limited, thiazoles such as M (2-mercaptobenzothiazole), DM (dibenzothiazyl disulfide), and CZ (N-cyclohexyl-2-benzothiazylsulfenamide);
A guanidine-based vulcanization accelerator such as PG (diphenylguanidine) can be used, and the amount of the vulcanization accelerator is determined mainly by the required vulcanization rate of the rubber. Generally, the amount is preferably 0.1 to 7 parts by weight, more preferably 1 to 5 parts by weight, per 100 parts by weight of the rubber component. Also, silica formulations generally require higher amounts of accelerator.

Examples of the process oil include paraffinic, naphthenic, and aromatic oils. For applications in which the enhancement of tensile strength and abrasion resistance is important, the aromatic oils improve hysteresis loss and low-temperature characteristics. Naphthene-based or paraffin-based is used for important applications. The amount of the naphthene-based or paraffin-based is preferably 0 to 100 parts by weight with respect to 100 parts by weight of the rubber component. Tends to deteriorate. In the present invention, in addition to these, antiaging agents commonly used in the rubber industry,
Additives such as zinc oxide, stearic acid, antioxidants, and antiozonants may be added. The rubber composition of the present invention is obtained by kneading using a kneading machine such as a roll or an internal mixer, and after molding, vulcanization is carried out, and the rubber composition is used for tire applications such as a tire tread. It can be used for rubber, belts, hoses and other industrial products, but is particularly preferably used as rubber for tire treads.

[0019]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, various measurement methods were performed by the following methods. (1) Weight average molecular weight The weight average molecular weight (Mw) was measured by gel permeation chromatography [GPC; HLC-802 manufactured by Tosoh Corporation].
0, column: GMH-XL (two in series) manufactured by Tosoh Corporation], and calculated in terms of polystyrene using the differential refractive index (RI) using monodisperse polystyrene as a standard. (2) Vinyl bond amount The vinyl bond amount (%) in the butadiene portion of the polymer is as follows:
It was measured by an infrared spectrometer and determined by the Morero method. (3) Bound styrene content It was determined from the integral ratio of the ¹ H-NMR spectrum as a percentage by weight based on the whole polymer.

(4) Breaking Strength The strength (breaking strength) of the vulcanized rubber at the time of cutting is JIS K6.
It was measured according to 251-1993, and was indicated by an index with Comparative Example 1 being 100. The larger the value, the better. (5) Wet skid resistance A skid tester (manufactured by Stanley London) reproduces and evaluates wet and dry road surfaces,
It was shown by an index with Comparative Example 1 being 100. The larger the value, the better. (6) Dry grip performance The stability of cornering on a tire of size 195 / 65R15 during running on a dry road surface was evaluated by feeling of two test drivers, and the index was set as an index with Comparative Example 1 being 100. The larger the value, the better. (7) Wear resistance Using a Lambourn abrasion tester, a test was conducted under the conditions of a slip ratio of 60% at room temperature, and the reciprocal of the wear amount was calculated as
It was shown by an index with Comparative Example 1 being 100. The larger the value, the better.

Production Example 1 83 g of cyclohexane, 4.7 g of styrene, 14 g of butadiene 14
g, and ditetrahydrofurylpropane 1.6
Then, 3 mmol of normal butyllithium (BuLi) and 3 mmol of normal butyl lithium were added, and a polymerization reaction was performed at 50 ° C. for 30 minutes. After the reaction, 0.5 ml of 2-propanol was added to stop the reaction. About the obtained copolymer (A-1), the amount of bound styrene and the weight average molecular weight (Mw) were measured by the above method. The results are shown in Table 1.

Production Examples 2 to 6 After replacing with nitrogen in a 1 liter sealed pressure-resistant glass container, 83 g of cyclohexane, 4.7 g of styrene, 14 g of butadiene 14
g, and ditetrahydrofurylpropane 1.6
Then, 3 mmol of normal butyllithium (BuLi) and 3 mmol of normal butyl lithium were added, and a polymerization reaction was performed at 50 ° C. for 30 minutes. Subsequently, 3 mmol of benzylideneaniline was added, and the mixture was reacted for 30 minutes. Further, 3 mmol of phenyl isocyanate was added, and the mixture was reacted for 30 minutes. Finally, 0.5 ml of water was added to stop the reaction to obtain a styrene-butadiene copolymer (A-4). Further, in the production example of the copolymer (A-4), except that the amount of normal butyl lithium was changed, the copolymers (A-2, A-
3, A-4, A-5 and A-6) were obtained. For the copolymers (A-2 to A-6) described above, the amount of bound styrene and the weight average molecular weight (Mw) were measured by the above-described methods. The results are shown in Table 1.

Production Examples 7 and 8 First, as a dilithium-based initiator (DiLi), using 1,3-diisopropenylbenzene and t-butyllithium, "Macromolecules" (1996) 2
9 , 2738-2745. Next, after replacing with nitrogen in a 1-liter closed pressure-resistant glass container, 83 g of cyclohexane, 4.7 g of styrene and 14 g of butadiene were introduced, and 2 mmol of ditetrahydrofurylpropane and 3 mmol of the dilithium catalyst prepared above were added. For 30 minutes to carry out a polymerization reaction. Subsequently, 6 mmol of benzylideneaniline was added and reacted for 30 minutes, and 6 mmol of phenyl isocyanate was further added and reacted for 30 minutes. Finally, 0.5 ml of water was added to stop the reaction, and a copolymer (A-8) was obtained. Also,
A copolymer (A-7) was obtained in the same manner as in the above Production Example of the copolymer (A-8) except that the amount of the dilithium catalyst was changed. For the copolymers (A-7 and A-8) described above, the amount of bound styrene and the weight average molecular weight (Mw) were measured by the above-described methods. The results are shown in Table 1.

[0024]

[Table 1]

[0025]

Production Example 9 300 g of cyclohexane, 32.5 g of butadiene monomer, 17.5 g of styrene monomer, 2,2-bis (tetrahydrofuryl) propane were placed in an 800 ml pressure-resistant glass container dried and purged with nitrogen. 0.16 mmol injected,
After adding 0.45 mmol of normal butyl lithium, polymerization was carried out at 50 ° C. for 2 hours. The polymerization system was uniform and transparent without any precipitation from the start to the end of the polymerization. The polymerization conversion was almost 100%. Styrene-butadiene copolymer rubber (B) thus obtained
Is 35% by weight of bound styrene, 40% of vinyl bound,
And the weight average molecular weight (Mw) was 700,000.

Examples 1 to 6 and Comparative Examples 1 and 2 According to Table 2, 100 parts by weight of the styrene-butadiene copolymer rubber (SBR rubber) of Production Example 9 were obtained by Production Examples 1 to 8. 40 parts by weight of a low molecular weight styrene-butadiene copolymer, 27 parts by weight of carbon black (manufactured by Tokai Carbon Co., Ltd., trade name: Seast KH (N339)), and 27 parts by weight of silica (manufactured by Nippon Silica Co., Ltd., trade name: Nipsil AQ) 27 Parts by weight, 2.5 parts by weight of a silane coupling agent [trade name: Si69, bis (3-triethoxysilylpropyl) tetrasulfide manufactured by Degussa], 2 parts by weight of stearic acid, and an antioxidant 6C [N- (1, 3-dimethylbutyl) -N'-phenyl-p-phenylenediamine] 1
Parts by weight to prepare a masterbatch. Further, 3 parts by weight of zinc white, 0.8 parts by weight of vulcanization accelerator DPG (diphenylguanidine), 1 part by weight of vulcanization accelerator DM (dibenzothiazyl disulfide), A rubber composition was prepared by blending 1 part by weight of a sulfur accelerator NS (Nt-butyl-2-benzothiazylsulfenamide) and 1.5 parts by weight of sulfur. The obtained rubber composition was vulcanized at 160 ° C. for 15 minutes, and the breaking strength, wet skid resistance, dry gripping property and abrasion resistance of each vulcanized rubber were measured by the above-mentioned methods. Table 2 shows the results.

[0028]

[Table 2]

As can be seen from the above table, the rubber compositions of Examples 1 to 6 containing a certain amount of a low molecular weight polymer having an amide bond in the present invention have at least breaking strength and abrasion resistance as compared with Comparative Example 1. It can be seen that the wet skid resistance and the dry skid property are significantly improved after the maintenance. In the rubber composition of Comparative Example 2, the breaking strength and abrasion resistance were deteriorated because the weight average molecular weight per amide bond did not satisfy the range in the present invention.

[0030]

According to the present invention, a novel polymer having a specific amount of an amide bond in a rubber component is blended in the rubber component to provide a high degree of fracture resistance and wear resistance without adversely affecting the rubber component. A rubber composition having both grip performance and fracture resistance can be obtained. This rubber composition can be widely applied to industrial products such as tires and vibration-proof rubber.

Continued on the front page F-term (reference) 4J002 AC01W AC03W AC06W AC08W AC11X BB15W BB18W BL01X BP032 GN01 4J100 AB00Q AB02Q AB03Q AB07Q AB16Q AS02P AS04P AS06P BA34H BA37H BA38H BC04Q BC43P CA01 CA04 CA31 HC31 DA

Claims (7)

[Claims] (1) In the molecule, -NH-C (= O)-,> NC
It has at least one amide bond represented by at least one selected from the group consisting of (= O) N <and> NC (= O) -O-, and has a weight average molecular weight per one amide bond. A polymer having a molecular weight of 500 to 100,000. 2. The polymer according to claim 1, wherein the weight average molecular weight per amide bond is 3,000 to 50,000. 3. A modified polymer obtained by modifying a terminal group of a homopolymer or a copolymer of a conjugated diene,
3. The polymer according to claim 1, wherein the polymer is a modified polymer obtained by modifying a terminal group of a copolymer of a conjugated diene and a monovinyl aromatic hydrocarbon. 4. 4. 100 parts by weight of a rubber component and -N in a molecule.
HC (= O)-,> NC (= O) N <, and> NC
It has at least one amide bond represented by at least one selected from the group consisting of (＝ O) —O—, and has a weight average molecular weight of 500 to 10 per one amide bond.
A rubber composition comprising 5 to 250 parts by weight of a 0000 polymer. 5. The rubber composition according to claim 4, wherein the weight average molecular weight per amide bond is 3,000 to 50,000. 6. 100 parts by weight of a rubber component and the polymer 2
The rubber composition according to claim 4, wherein the rubber composition comprises 0 to 150 parts by weight. 7. The rubber composition according to claim 4, wherein the rubber component is a diene rubber.