JPS608341A - Rubber composition for tire tread - Google Patents

Abstract

PURPOSE:To provide the titled composition giving a tire tread rubber material having excellent wet-skid resistance and impact resilience, and improved safety, etc., and containing a styrene-butadiene copolymer rubber containing benzophenone compound in the molecular chain. CONSTITUTION:The objective composition is obtained by compounding (A) 20- 95wt% styrene-butadiene copolymer rubber containing >=0.1mol of (thio)benzophenone compound introduced into 1mol of the molecular chain, having a bonded styrene content of 10-20wt%, the 1,2-bond content in the butadiene unit of 30-50%, and a Mooney viscosity of 20-150, (B) 5-60wt% styrene-butadiene copolymer rubber, etc. having a bonded styrene content of 10-40wt% and the 1,2-bond content in the butadiene unit of 10-40%, and (C) 0-40wt% polybutadiene having a 1,2-bond content of <=20% and a Mooney viscosity of 20-100, as the rubber components.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides gonometry compositions with improved recoil modulus. For details, see molecule q.

Pennphenone WtMatathiobenzophenone d2Q
The present invention relates to a rubber composition for a tire tread containing a styrene-butadiene copolymer rubber as a rubber component.

Recently, from an introspective point of view toward low fuel consumption and safety of automobiles, in particular, reduction of rolling resistance of tires and excellent braking performance on wet road surfaces, that is, improvement of Wet Skit 41 (J'4.') has been done.

In general, the characteristics of these tires are tread rubber, [4 (2
The dynamic viscosity of T
transaction of engineering, R0 King, l volume 40,
239-256, 1964].

In order to reduce the rolling resistance of tires, it is necessary for the tread rubber material to have a high recoil modulus, and considering the driving conditions of the car, this recoil modulus needs to be evaluated at temperatures from 50C to around 70C. There is. On the other hand, in order to improve braking performance on wet roads, which is an important performance in terms of vehicle safety, it is necessary to have a high wet skid resistance as measured by the British Portable Skid Tester.
The tread rubber material needs to have a large energy loss due to friction resistance that occurs when the tire is braked and slides on the road surface.In the past, in order to satisfy these two conflicting characteristics, raw materials were As the rubber, emulsified 111-styrene-butadiene copolymer rubber, high cis-
Polybutadiene rubber, low cis-polybutadiene rubber, styrene-butadiene rubber obtained using an organolithium compound catalyst, natural rubber, and high-cis isobrene rubber have been used singly or in combination.

It wasn't quite satisfactory. In other words, in order to obtain high impact elasticity, one must increase the blending ratio of rubber with poor wet skid resistance such as low cis-polybutadiene rubber or natural rubber, reduce the amount of filler such as carbon black, or increase the amount of sulfur. It was necessary to increase the amount of vulcanizing agent such as. However, such a method has disadvantages in that wet skid resistance is reduced and mechanical properties are deteriorated. On the other hand, when trying to obtain high wet skid resistance, a styrene-butadiene copolymer with a relatively large amount of bonded styrene (for example, more than 50 pieces of bonded styrene) is used. Increase the blending ratio of rubber with excellent wet skid resistance such as polybutadiene rubber with a relatively high 1.2-bond content (for example, 160% or more), or add fillers such as carbon black or process oil. However, this method had the disadvantage that the rebound elasticity was reduced.

Therefore, the actual situation is that the composition of the raw rubber is determined so that the mechanical properties are within a practically acceptable range, and the wet skid resistance and anti-flap elasticity are in the best balance within a practically acceptable range. Ta. For this reason, it was thought that the ability to achieve a balance between wet skid resistance and anti-shock elasticity by combining conventional rubbers had reached its limit.

As a result of intensive research aimed at solving the above-mentioned drawbacks, the present inventors have discovered a rubber composition containing as a rubber component a styrene-butadiene copolymer rubber in which benzophenones or thiobenzophenones have been introduced into the rubber molecular chain. Compared to a rubber composition containing the same styrene-pumediene copolymer rubber in which the compound has not been introduced, the rubber composition significantly improves the impact resilience without reducing wet skid resistance, and also has the characteristics of high impact resilience. We have discovered that it is possible to improve mechanical properties such as abrasion resistance and achieve a balance between anti-elasticity and wet skid resistance by increasing the amount of filler such as carbon black if necessary, and have arrived at the present invention. It is something that

That is, 1 the present invention is characterized in that at least 0.1 mole of benzophenones or thiopenzophenones is introduced into the styrene-butadiene copolymer rubber molecular chain per mole of the rubber molecular chain, and the amount of bound styrene is 10 to 20% by weight, butadiene. 1.2-Binding metal content of the unit part is 50 to 50%, Mooney viscosity 0 111 + 4 ° 1 ooc) is 20 to 150; , (a) The amount of bound styrene is 10 to 4 oii
%, 1.2-bond content of butadiene unit moiety is 10%
More than 40% less? Mt'j of styrene-butadiene copolymer rubber and/or (b) The amount of bound styrene exceeds 20% by weight and is 40% by weight or less, and 1.2- to 1-unit portion of butane.
Styrene-Fudgeene copolymer rubber (Jr) 60 to 5 weight M% with a bonding metal part of 40 to 50 inches, a 1.2-bond angle: ht of 20 inches or less, Mooney viscosity (λ
a.

Polybutadiene rubber (I
II) The present invention provides a rubber silk composition for tire treads that reduces rolling resistance without impairing wet skid resistance and comprises 4 o to 0 weight M% as a rubber component. By using a rubber compound for tire tread, it is possible to obtain a tire that has an excellent balance between rolling resistance, which is important for the tire performance mentioned above, and braking performance on wet road surfaces, that is, wet skid resistance. It is possible to manufacture a tire that does not require a particular wet skid resistance value, but only requires a high one-elastic modulus.

The styrene-butadiene copolymer rubber in which benzophenones or thiobenzophenones are introduced into the molecular chain used in the present invention is obtained by using an alkali metal-based catalyst commonly used in solution polymerization, and an alkali metal is bonded to the end of the molecular chain. A styrene-butadiene copolymer obtained by reacting a styrene-butadiene copolymer rubber, or a product obtained by adding an alkali metal in a post-reaction to the rubber obtained using the catalyst, with benzophenones or thiobenzophenones. The compound has a general formula substituent at a carbon-carbon bond at the end of the rubber molecular chain or in other molecular chains, M represents 0 or S, and m and n represent integers, respectively. ) is a styrene-butadiene copolymer rubber introduced as an atomic group shown in Benzophenones and thiobenzophenones such as 4,4'-bis(dimethylamino)-
Benzophenone, 4,4'-bis(diethylamino)-
Benzophenone, 4,4'-bis(dibutylamino)-
Benzophenone, A, 4'-diaminobenzophenone,
At least one amino group, alkylamino group, or 1. on one or both benzene rings, such as 4-dimethylaminopenzophenone and the like and their corresponding thiobenzophenones. Particularly preferred are benzophenones having a dialkylamino group.

In addition to the above-mentioned amino group, benzophenones having at least one alkoke group, /.rogen or hydrocarbon residue as a substituent, such as 4,4'-diaminobenzophenone, 3,4-dimethoxybenzophenone, 4,4'
-Dimethylbenzophenone.

5j'') Cyclobenzophenone, 4-methyl-4'-methquinepenzophenone, 2,2'-tetramethylbenzophenone, 2,2'-dichlorobenzophenone, etc. and their corresponding thiobenzophenones can also be used as substituents. Benzophenones and thiobenzophenones without the following can also be used: 〇Hensophenones and Hthiobenzophenones Ha: cycloalkyl groups, cycloalkyl groups, alkenyl groups,
1M is O for substituents selected from alkoxy groups, amino groups, alkylamino groups, dialkylamino groups, and halogens.
or S is a compound represented by 1m and nt, respectively, where m and n represent an integer in which the sum of m and n is 1 to 10.

For example, the styrene-butadiene Jtdli rubber containing benzophenones or thiobenzophenones introduced into the molecule may be prepared by polymerizing methylene-butadiene copolymer rubber using an alkali metal-based catalyst and completing one polymerization reaction in the rubber solution. Method 9. Adding benzophenones or expanded thiobenzophenones to Examples include a method in which alkaline gold is added to the rubber in a solution of styrene-butadiene copolymer rubber using a metal-based catalyst, and then benzophenones or thiobenzophenones are added.

The alkali metal-based catalysts used in the polymerization reaction and addition reaction are lithium, sodium, rubidium, and 11 metal elements used in ordinary solution polymerization, or their hydrocarbon compounds or Q-positive compounds. Complex with (f!
For example, n-butylrichiuno.

2-naphthyllithium, potassium-tetrahydronerane complex, potassium-shedoyethane complex, etc.).

Benzophenones or thiobenzophenone introduced into the styrene-butadiene copolymer rubber: q p6゜ 0.1 mol per mol of rubber molecular chain on average Jet't''
be. (), if less than 1 mol, the improvement in anti-reflective elasticity is (El
<) Not possible. Preferably t is 0.3 mol or more, more preferably 0.5 mol or more, particularly preferably 0.7 mol,
/l/ or more, but if it exceeds 5 moles, the rubber elasticity will be lost, which is not preferable.

The styrene-butadiene copolymer rubber (I) in which benzophenones or thiobenzophenones are introduced into the rubber molecular chain has a bound styrene content of 10 to 200% by weight, a 1.2-bond content of the butadiene unit portion of 60 to 50%, and a Mooney The styrene-mediene co-compatible rubber has a viscosity (ML1+4.1 onυ) of 20 to 150.

In the styrene-mediene copolymer rubber (I), if the bound styrene content and the 1.2-bond content of the butadiene unit portion are out of the above range, the abrasion resistance, anti-friction modulus, wet skid resistance, etc. This is not preferable because it reduces the

Further, if the Mooney viscosity (ML, +4.1000) is less than 20, the recoil elasticity will decrease, and if it exceeds 150, the kneading processability will be poor and the mechanical properties such as tensile strength will decrease, so it is preferable than 0, which is undesirable. 60 to 160. (I)
02 is preferably 20 to 95% by weight of the total rubber component.
At 20% by weight, the effect of improving rebound elasticity is small and the object of the present invention cannot be achieved, and at more than 95% by weight, the composition has almost the same properties as the composition obtained using (I) alone, and wet skid resistance or resistance It is undesirable because of its poor abrasion resistance.

A styrene rubber that does not contain nzophenone in its main chain, which is used in combination with (I)! In the diene compound rubber (11) (c) a), the amount of bound styrene kJ: '1
o to 40 weight ji% has a good bite, butadiene-IV'i
The 1.2-bond content of the position moiety is preferably 10% or more and less than 40%. Butadiene-1'1 to λ1 to 1.2-bond content is preferably 40 to 50. In O (a) and (b), the bond content is 1, and if it deviates from the above range, wet skid resistance If the 1.2-bonded claw of the unit part of the 1.2-metal unit is undesirable because it will significantly reduce the recoil elasticity, the wet skid resistance and Abrasion 1'F is 11 (F), so it is preferable, but not.Mooney viscosity is preferably 20 to 150, and if it is less than 20, the rebound elasticity is 7) (decreased, and 150
Exceeding this is not preferable because it results in poor workability and reduced mechanical properties. More preferably L60 to 130
(Jl) Preferably 60 to 5% by weight of the company's total rubber components; if it exceeds 60% by weight, the rebound elasticity decreases and
If it is less than that, the wet skid resistance or abrasion resistance will be poor, which is not preferable.

1. Polybutadiene rubber (III) with a 2-bond content of 20% or less can be used as necessary to improve soil abrasion resistance, but if it contains 1,2-bonds and i1t exceeds 20%, its The muni viscosity is preferably 20 to 100, which is undesirable because the purpose cannot be achieved.If it is less than 20, the rebound elasticity will be significantly reduced and the purpose of the present invention cannot be achieved, and if it exceeds 100, the kneading processability will be poor. The value is preferably 0 to 80, which is undesirable because mechanical properties are deteriorated. (
(1) Preferably, the content of 1) is 40 or less of the total rubber components. 4
Exceeding 0 weight contact is not preferable because the wet skid resistance will drop significantly. The weight ratio is preferably 50% by weight or less.

All or part of the rubber components used in the present invention can be used as oil-extended rubber.The rubber composition for tire treads of the present invention is an object of the present invention.

Various compounding agents commonly used in the rubber industry depending on the application, such as sulfuric acid, suderic acid, zinc white, various 14 accelerators (thiazole type, thiuram type, sulfuric acid type, etc.),
Reinforcing agents for various grades of carbon black such as T (AF, SAF, etc., silica, Calcilla carbonate LA, 'etc.
Fillers, process oils, etc. can be selected as appropriate, and the mixture is mixed using a roll, pant, etc. mixer to form a blend.

After the molding and vulcanization process, 1 IJl of the desired tire is manufactured.

The rubber composition of the present invention has a high level of anti-t, 1:
It is suitable as a rubber material for automobile tire treads, especially for improved safety and fuel consumption, as it can harmonize the ratio of 1% and wet skid resistance, but it can also be used for bicycle tires. I can do it.

Hereinafter, the present invention will be specifically explained with reference to Examples.・Manufacture 1
Example fil Styrene with benzophenone tip 1 and thiobenzophenones introduced into the main chain used in the following examples.
Butadiene copolymer rubber (hereinafter sometimes abbreviated as NBR)
The manufacturing method is shown below.

After washing and drying a stainless steel reactor with an internal volume of 2-e and purging it with dry nitrogen, 40 to 80 g of styrene was added.
5-butadiene 120-1601, n-hexane 6'0
07-1n-Butyllithium 1,2 mmoJ% diethylene glycol dimethyl ether (diglyme) 0.
24 mmoJ was added and the mixture was incubated at a temperature of 45-60 υ for 60-120 minutes while stirring the contents. After the polymerization reaction was completed, a catalytic amount of t5 moles of 4.4'-bis(diethylamino)benzophenone was added, and after stirring for 5 minutes,
J-coalescence in the polymerization reactor? The 8 liquid was taken out into a methanol solution containing 1.5% by weight of 2.6-di-t-butyl-P-cresol (BHT), and the resulting polymer was coagulated. It was dried under reduced pressure at 6oc for 24 hours and the Mooney viscosity was measured [5nR
(zl]. In the same manner, SDR in which the benzophenone was changed to the corresponding thiobenzophenone was also prepared [S B
R(2')].

After the completion of the polymerization, the polymer solution was taken out into a BHT-containing memenol solution without adding the (thio)benzophenone, and the resulting polymer was coagulated, and a dried polymer was obtained in the same manner as above. [S B rt tl+, (31
, (4)]0(S', l il+ prepared with 5BR(1
) in benzene. S, use the same operation as il+
The BR was solidified. Repeat this operation three times to remove the catalyst residue in the SBR. Inui? G-BR was obtained.

This nBn ID[]17- is dried into benzene 1τ+t+
O! n-butyllithium lz 3.5 in a solution dissolved in 7.
mmol and tetramethylethylenediamine 3.5
mmnJ was added and reacted at 70 U for 1 hour.

Benzophenolated fl used in 11+ in the next step Monowo 2
．． After adding 7 mmojl and reacting for 5 minutes, 1. It was coagulated and dried in the same manner as described above [8f3R(5)]. Table 1 shows the microstructure, viscosity, and (thio)benzophenone introduction M of the rubber prepared with Yk of 7 or more.

The microstructure was measured by conventional infrared spectroscopy.
Introduction of thio)benzophenones-1 or 1B(+-NMR
EXAMPLE As a base composition for tire treads, various compounding agents and raw rubber of the compounding prescriptions shown in Table 2 were mixed in a 250ml Prabender lubmixer to obtain each rubber compound. n' acid was obtained. Sulfur and vulcanization (J, accelerator) were used in amounts that would achieve the optimum state when vulcanizing each rubber compounding composition.

A test piece was prepared by press vulcanization at 160C for 15 to 30 minutes.

aC2 table layout outside method 1 (λ family rubber (see table 3) 10 (]Oki!+1.j
'tl to HAF' carbon black 5017 Aromatic process oil 5 〃 Z n ON o 3 3 ” Sudearin r value 2-/ The strength properties of the vulcanized product of each rubber compound composition were determined according to J-Ko E3 K-6301. , - Also, the rebound elasticity was measured using a Dunlop trypsometer at a temperature of 55C.Wet skid resistance was measured at 21C using a Votaple skid desk (manufactured by Stanley Co., Ltd.).
The pure amount of ◎ pico r) was measured using a STME-305-74 surface (3M outdoor type B, black safety walk), calculated by , and expressed as an index. stomach,
The foot was measured using the Gutdrich 2 Pico Abrasion Test, calculated using , and displayed as an index. The above results are shown in Table 6.

From the results shown in Table 51, it can be seen that the rebound modulus of inventive examples 5.6.
It can be seen that it is 6 points higher.

Patent applicant: Zeon Corporation

Claims (1)

[Claims] A bond in which at least 0.1 mol of pentuphenones or thiopenzophenones is introduced per 1 mol of the rubber molecule chain into the styrene-butadiene copolymer rubber molecule chain y, f V :
The styrene-butadiene copolymer rubber ('I ) 20 to all 95 weights i
&% and (a) the amount of bound styrene is 10 to 40 by weight,
1.2-Styrene-butadiene copolymer rubber in which the butadiene unit content is 10% or more and less than 40% and/or (b) the amount of bound styrene exceeds 207 JjiJ,
40% by weight or less, styrene-butadiene copolymer rubber (II) with a 1.2-bond content of the butadiene unit portion of 4o to 50%, 6o to 5 g jib-, and a 1.2-bond content ik of 20% or less So, Mooney viscosity (MTJ ++
4. Polybutadiene (100℃) with a temperature of 20 to 100℃
III) 40~0fii! :%t Rubber composition for tire tread as a rubber component.