JPH05295174A - Rubbery polymer composition - Google Patents

Abstract

PURPOSE:To provide the objective compsn. which is suitable for producing a tire tread excellent in wet grip and ice grip, resistance to low-temp. breaking, impact resilience, and abrasion resistance and causing only low heat generation. CONSTITUTION:The compsn. comprises 40-85wt.% SBR (an organolithium compd. catalyst) having a Tg by DSC of -30 to -10 deg.C, a wt. ratio of styrene/butadiene of 30/70-50/50, a vinyl bond content in butadiene parts of 25-50mol%, and a Mooney viscosity of 80-200, and 60-15wt.% BR or SBR (an organolithium compd. catalyst) having a Tg by DSC of -100 to -75 deg.C, a wt. ratio of styrene/ butadiene of 0/100-10/90, and a Mooney viscosity of 30-200, and has, as the compsn., a wt. ratio of styrene/butadiene of 18/82-35/65, a Mooney viscosity of 80-200, and two Tg's by DSC of -40 to -10 deg.C and -70 deg.C or lower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber-like polymer composition, and more particularly to a rubber-like polymer composition which provides good grip performance and low temperature rupture performance when used in tire tread applications.

[0002]

2. Description of the Related Art In recent years, with the development of motorization, various performances such as safety, driving stability, economy, habitability, and pollution-free have been improved more than ever before with respect to tires mounted on automobiles. Is desired. In particular, as the driving ability of automobiles has been improved and the highways have been improved, improvements in braking characteristics, steering stability, and cornering characteristics during high-speed driving have been demanded, and due to the wider range of activities, it is sufficient even in cold regions. It has become necessary to have excellent maneuverability.

Since the steering performance of a tire is mainly affected by the grip performance of a tire tread, it is necessary to increase the coefficient of friction with the road surface by using a composition having a high hysteresis loss as a tread rubber composition. Is widely practiced. In order to increase the hysteresis loss of the tread rubber composition, as a raw material rubber to be used, the glass transition temperature (Tg:
A method of using a rubber-like polymer having an extrapolation start temperature (measured by DSC) and a method of blending a large amount of carbon black having a small particle size and a large surface area are used.

However, in the method using a raw material rubber having a high Tg, the higher the Tg of the raw material rubber, the more the hysteresis loss increases, but the compound becomes hard at low temperature and the grip performance of the tire in a cold region of 5 ° C. or lower. It is considered that the Tg of the raw material rubber used is about -30 ° C at the highest because the performance on snow and ice is extremely deteriorated. On the other hand, the use of carbon black with a small particle size increases the heat generation of the tread compound and increases the rolling resistance of the tire, and in the extreme case causes problems such as blowout of the tire, and such carbon is also used. It has a problem that it is relatively difficult to disperse it uniformly.

As described above, it has been difficult to achieve both the grip performance and the low temperature performance of the tire tread compound or the grip performance and the rolling resistance performance of the tire tread compound by the conventional general technique. In order to solve such problems, a method for blending a polymer having a high Tg and a polymer having a low Tg, and a rubber composition for a tire tread using a block polymer having a polymer block having a high Tg and a polymer block having a low Tg are provided. Several have been proposed.

For example, Japanese Patent Laid-Open No. 56-112947 discloses a rubbery polymer having a high Tg and a styrene content of 3 to 3.
So-called high vinyl SBR having a vinyl content of 30% and a butadiene content of 60 to 95% is used, and Tg is low as a low Tg component.
A rubber tread rubber composition prepared by blending a high Tg component and a low Tg component using a rubbery polymer of 40 ° C. or lower is improved in wet grip performance and rolling resistance, and has wear resistance and durability. It is noted that the sex is improved. However, there is no mention of compatibility between grip performance and low temperature destruction performance.

Further, JP-A-63-142054 discloses that a block polymer elastomer having a high Tg polymer block and a low Tg polymer block and a tire containing the same have low rolling resistance and high wet grip performance. It has been proposed to exhibit high abrasion resistance. In the publication, the content of the aromatic vinyl compound as the high Tg polymer block (A) is 52 to 90.
%, Aromatic vinyl compound-conjugated diene copolymer block having a conjugated diene unit vinyl content of 20% by weight or less, and a Tg of -40 when the content of the aromatic vinyl compound is less than 20% by weight as a polymer block having a low Tg. Consists of a conjugated diene homopolymer block or an aromatic vinyl compound-conjugated diene copolymer block (B) having a temperature of not higher than 0 ° C., and a block (A) / block (B) ratio of 5 to 50.
% / 95-50% by weight, indicating that the blocks (A) and (B) are incompatible. Further, in the same publication, 1 of a vulcanized product which becomes this tire composition
In the temperature change curve of Tan δ measured at 0 Hz, T
It is preferable for the purpose that the first maximum value of an δ is in the range of + 30 ° C. to −20 ° C. and the second maximum value is −40 ° C. or less for the above purpose, block (A) and block (B). Have been shown to be preferably present in the same polymer. However, this JP-A-63-142054
Even in the technology described in the publication, no proposal has been made regarding compatibility between grip performance and low temperature destruction performance.

Further, Japanese Patent Publication No. 3-77223 discloses that
As a rubber composition for tire treads that has low heat generation properties and wet grip characteristics, and also has improved low temperature performance,
A rubber composition having a specific storage shear modulus at -30 ° C, using a mixture of a styrene-butadiene copolymer rubber having a Tg of -30 ° C to -50 ° C and a polybutadiene rubber having a Tg of -70 ° C or less as a raw material rubber. It is proposed to use objects. Further, according to Japanese Patent Publication No. 3-77223, a styrene-butadiene copolymer having a Tg of -30 ° C or higher has poor compatibility with polybutadiene rubber and causes phase separation to lose the significance of blending. It is described that it is not preferable, and that polybutadiene rubber having cis-1,4 bond of 90% or more is preferable.
Further, Japanese Patent Publication No. 3-77222 discloses a Japanese Patent Publication No.
A rubber composition for tires in which polynorbornene is further added to the rubber mixture described in Japanese Patent No. 77223 has been proposed for almost the same purpose. These two proposed technologies have been improved over the previous technologies, but have not reached a significant improvement in low temperature performance.

Further, JP-A-2-132145 discloses a rubber composition for a tire tread, which has a stable grip performance over a wide temperature range and is excellent in gripping snow and ice road surfaces, and has a Tg of -20 ° C. At + 15 ° C, the bound temperature range of Tg is 12 including 20 to 50% by weight of bound styrene.
A styrene-butadiene copolymer block below ℃
g is -100 ° C to -70 ° C and Tg transition temperature range is 12 ° C.
A method of using a styrene-butadiene block copolymer rubber which is composed of the following butadiene blocks and has a Tg difference of 60 ° C. or more between these two blocks is also proposed. In this method, it is important that the two blocks are incompatible or semi-compatible with each other in order to achieve the desired performance. Therefore, when the difference between the Tg of the two blocks is 60 ° C. or more, the transition of the Tg of each block is It is stated that the temperature range needs to be as narrow as 12 ° C. or less. However, even with this method, a sufficient performance balance is not always obtained.

[0010]

DISCLOSURE OF THE INVENTION The present invention provides a passenger car which has both a low temperature destructive performance and a wet grip performance at a high level, and has a good ice grip performance, a good low heat generation property, and a good wear resistance. An object of the present invention is to provide a rubber composition of a raw material rubber that provides a rubber compound for a tire tread.

[0011]

In order to achieve the above object, the present invention provides, as a raw material rubber for a rubber composition for tire tread, a high Tg rubbery polymer having a specific limited polymer structure and a specific rubbery polymer. It is proposed to use a rubber composition comprising a low Tg rubber-like polymer having a limited polymer structure and a specific ratio of the two.

The present invention is, as the component (A), a styrene-butadiene random copolymer polymerized by an organolithium compound catalyst in an inert solvent, wherein (1) the glass transition temperature (Tg) measured by DSC. Is -3
0 to -10 ° C (2) Weight ratio of bound styrene / bound butadiene is 30
/ 70 to 50/50 (3) The vinyl bond content of the microstructure of the butadiene portion is 2
5-50 mol% (4) Mooney viscosity (ML1 + 4,100 ° C) is 80-
40 to 85% by weight of a rubbery polymer which is 200 and a polybutadiene or a styrene-butadiene random copolymer polymerized by an organolithium compound catalyst as an ingredient (B) in an inert solvent, (1) DSC Glass transition temperature (Tg) measured by
00-75 ° C (2) Weight ratio of bound styrene / bound butadiene is 0 /
100 to 10/90 (3) Mooney viscosity (ML1 + 4, 100 ° C) is 30 to
200 to 60% by weight of the rubbery polymer, and the total weight ratio of bound styrene / bound butadiene is 18/8.
2-35 / 65, Mooney viscosity (ML1 + 4,100
C) is 80 to 200, and Tg measured by DSC is -40.
It is a rubbery polymer composition characterized by being in two ranges of -70 ° C and -70 ° C.

The present invention will be described in detail below. In the case where the rubbery polymer composition of the present invention is used as a vulcanized rubber in a tire tread, the high Tg component (A) and the low Tg component (B) each have a specific range in order to achieve the above object. It has Tg and (A) component and (B)
The components must be incompatible in the vulcanized state and exhibit the form of microphase separation. To this end, the styrene-butadiene random copolymer or polybutadiene of each component must limit the ratio of bound styrene / bound butadiene and the microstructure of the butadiene portion. The present inventors do not consider that a difference in Tg between the component (A) and the component (B) is an important condition for incompatibility, but it is important for a difference in the composition of both components to be incompatible. The present invention has been made based on the finding that the above conditions are satisfied.

In the prior art, styrene-butadiene random copolymers or polybutadienes were limited in bound styrene / bound butadiene ratio and in the microstructure of the butadiene moieties to identify the Tg of the rubbery polymer. However, in the present invention, the combination of the styrene / butadiene ratio of each component and the butadiene microstructure is important in order to bring about the state of microphase separation in the vulcanized state together with the limitation of Tg. When the component (A) and the component (B) are compatible with each other in the vulcanized state, the tread composition has the desired performance even if the Tg of the component (A) and the component (B) are in the specific range. I can't.

In order to improve the wet grip performance, Tan δ of the vulcanized compound of the tire tread at around 0 ° C. (usually measured at 1 to 100 Hz, 1 in the present invention)
It is well known that it is necessary to increase the value of (measured at 0 Hz) (described in JP-B-3-77223 and JP-A-63-142054). For that purpose, it is considered desirable to use a rubber-like polymer having a maximum value of Tan δ at around 0 ° C. as a tread compound, but in that case, the storage elastic modulus around 0 ° C. is also increased at the same time. Since the composition rapidly hardens at 0 ° C or lower, causing deterioration in low temperature fracture characteristics and deterioration in ice grip performance, a rubber-like polymer having a Tan δ maximum value of a vulcanized compound near 0 ° C is used alone. Nothing is done. In order to maintain the low temperature rupture property and the ice grip performance, a rubber-like polymer having a maximum Tan δ value of about −10 ° C. or less when used as a vulcanized compound is used.
They are rubbery polymers having a Tg of -30 ° C or less measured by DSC.

However, in the present invention, the rubber composition is required to have both wet grip performance and low temperature fracture performance.
Achieved by combining a high Tg component and a low Tg component that cause microphase separation in the vulcanized state. In the present invention, in order to improve the wet grip performance, a styrene-butadiene random copolymer having a Tg measured by DSC of −30 ° C. to −10 ° C. is used as the component (A) of the rubber-like polymer. In this case, the maximum value of Tan δ of the vulcanized composition is in the range of approximately −10 to + 5 ° C., but the presence of the component (B) does not deteriorate the low-temperature fracture performance. It is more preferable that the maximum value of Tan δ be within a range of approximately −10 to + 0 ° C. by further controlling the weight ratio of the components (A) and (B) and the Tg of each component.

The styrene-butadiene random copolymer (hereinafter referred to as SBR) as the component (A) will be described below. The SBR of the component (A) is an SBR polymerized by an organolithium compound catalyst in an inert solvent, and (1) has a glass transition temperature (Tg) of -3 measured by DSC.
0 to -10 ° C (2) Weight ratio of bound styrene / bound butadiene is 30
/ 70 to 50/50 (3) The vinyl bond content of the microstructure of the butadiene portion is 2
5-50 mol% (4) Mooney viscosity (ML1 + 4,100 ° C) is 80-
200 rubbery polymer.

Therefore, in the so-called emulsion polymerization SBR obtained by copolymerizing styrene and butadiene with a radical polymerization catalyst, the microstructure of the butadiene portion is outside the scope of the present invention and even if Tg is within the scope of the present invention. Also,
The compatibility with the rubber-like polymer as the component (B) is different,
Inferior ice grip performance. (A) DS of component SBR
Glass transition temperature (Tg) measured by C is -30 to -10.
It is in the range of ° C. The Tg limited in the present invention is an extrapolation start temperature measured using a DSC at a temperature rising rate of 10 ° C./min. If the Tg of the component (A) is less than -30 ° C, the wet grip performance is not sufficient, while if it exceeds -10 ° C, the low temperature fracture performance is deteriorated. Tg of component (A) is -25 ° C
The range of to -15 ° C is preferable. (A) Component SBR T
The g is determined by the weight ratio of bound styrene / bound butadiene described later and the amount of vinyl / cis / trans in the microstructure of the butadiene portion. The component SBR (A) has a glass transition temperature transition width (ΔTg: difference between extrapolation start temperature and extrapolation end temperature) of 20 ° C. or less measured by DSC,
It is preferable in that the microphase separation of the component (A) and the component (B) is effective and the wet grip performance is improved.

Next, the weight ratio of bound styrene / bound butadiene of component (A) SBR is 30/70 to 50/50.
Is. If the weight ratio of bound styrene / bound butadiene is less than 30/70, the compatibility with the component (B) is improved and the object of the present invention is not achieved. On the other hand, the weight ratio of bound styrene / bound butadiene is 50/50. Beyond,
The storage elastic modulus around 0 ° C is high and the ice grip performance is poor. The weight ratio of bound styrene / bound butadiene of component (A) SBR is preferably 33/67 to 47/53.

The vinyl bond content of the microstructure of the butadiene portion of component (A) SBR is in the range of 25 to 50 mol%. When the vinyl bond amount is less than 25 mol%, the low exothermicity is deteriorated, while when the vinyl bond amount exceeds 50 mol%, the compatibility with the component (B) increases and the wet grip improving effect is reduced. The vinyl bond content of the microstructure of the butadiene portion of component (A) SBR is preferably in the range of 30 to 45%, particularly preferably in the range of 33 to 40%. The amount of other microstructures (cis bond and trans bond) of the butadiene portion is SBR polymerized with an organolithium catalyst, and therefore has a value in a range substantially corresponding to the amount of vinyl.

Further, the Mooney viscosity (ML1 + 4, 100 ° C.) of the component (A) SBR is in the range of 80 to 200. When the Mooney viscosity is less than 80, the low heat build-up and abrasion resistance are poor, while when the Mooney viscosity is more than 200, the processability of the compound is deteriorated. The Mooney viscosity is preferably in the range of 80 to 150. Next, in the present invention, as the component (B), polybutadiene having a specific polymer structure having a Tg of −75 ° C. or less (hereinafter referred to as BR) or SBR is used for improving the low temperature fracture performance. Due to the presence of the component (B), the rubbery polymer composition of the present invention shows another Tan δ maximum value in the region of −50 ° C. or lower in the case of a vulcanized rubber composition.

The BR or SBR of the component (B) will be described below. The component (B) is polybutadiene or a styrene-butadiene random copolymer polymerized by an organolithium compound catalyst in an inert solvent, and (1) has a glass transition temperature (Tg) of -1 measured by DSC.
00-75 ° C (2) Weight ratio of bound styrene / bound butadiene is 0 /
100 to 10/90 (3) Mooney viscosity (ML1 + 4, 100 ° C) is 30 to
200 rubbery polymer.

Therefore, the cis-1,4 bond content obtained by the cobalt-based polymerization catalyst or the nickel-based polymerization catalyst is 90%.
The above-mentioned high-cis polybutadiene and so-called emulsion-polymerized polybutadiene obtained with a radical polymerization catalyst do not correspond to the above-mentioned limitation of the component (B). Since these have different microstructures of the butadiene portion, they have different compatibility with the component (A) and do not achieve the object of the present invention. The high-cis polybutadiene has the same effect as the present invention with respect to the low temperature fracture performance, but the wet grip performance of the composition is markedly deteriorated.

The Tg of BR or SBR of the component (B) is-
It is in the range of 100 to -75 ° C. BR obtained with a lithium-based catalyst has a Tg of −100 ° C. or higher. BR or S
When the Tg of BR exceeds -75 ° C, the purpose of improving the low temperature fracture performance cannot be achieved. The Tg of BR or SBR of the component (B) is preferably in the range of -100 to -80 ° C. The Tg of BR or SBR of the component (B) is determined by the weight ratio of bound styrene / bound butadiene and the microstructure (cis / trans / vinyl) of the budadien moiety.

The SBR or BR of the component (B) is a DSC
Glass transition temperature transition width (ΔTg) measured at 10 ℃
It is preferable that the amount is within the range in order to effectively perform the micro phase separation of the component (A) and the component (B) and improve the wet grip performance. Next, the weight ratio of the bound styrene / bound butadiene of the component (B) is in the range of 0/100 to 10/90. Bound styrene / bound butadiene weight ratio of 1
When it exceeds 0/90, the difference in the amount of styrene from the component (A) becomes small, and microphase separation does not occur during vulcanization. The vinyl bond content of the microstructure of the butadiene portion of the BR or SBR of the component (B) may be any value as long as Tg is within the range of the above-mentioned component (B), but is maximum within the above-mentioned limit of Tg. The vinyl bond amount of BR is about 35 mol%, and the upper limit of the vinyl bond amount of the component (B) becomes lower as the amount of styrene increases. The other microstructure of the butadiene portion is BR and SBR polymerized with a lithium-based catalyst, and if the Tg of the component (B) is within the range, the cis-1,4 bond content is 25 to
40 mol%, and the amount of trans-1,4 bonded is in the range of 30 to 55%.

The Mooney viscosity (ML1 + 4,100 ° C.) of BR or SBR as the component (B) is in the range of 30 to 200. When the Mooney viscosity is lower than 30, low heat buildup
The effect of improving abrasion resistance is lost, and the processability of the composition having a Mooney viscosity of more than 200 deteriorates. In the present invention, the Mooney viscosity of the component (B) is preferably in the range of 50 to 150. In the present invention, the weight ratio of the component (A) and the component (B) is (A) /
(B) = in the range of 40/60 to 85/15. (A)
If the amount of the component is less than 40% by weight, the wet grip performance is not sufficient, while if the amount of the component (A) exceeds 85% by weight, the low temperature fracture performance is deteriorated. The weight ratio of the component (A) and the component (B) is (A) / (B) = 50/50 to 80/2.
A range of 0 is preferred.

In the present invention, the total weight ratio of bound styrene / bound butadiene of the rubber composition comprising the components (A) and (B) is 18/82 to 35/65, and the Mooney viscosity (ML1 + 4,100 ° C.) is It is in the range of 80 to 200. Weight ratio of bound styrene / bound butadiene is 18 /
When it is lower than 82, the wet grip performance becomes insufficient, and when it is higher than 35/65, the ice grip performance deteriorates. Further, when the Mooney viscosity is lower than 80, the low heat build-up is inferior, and when it exceeds 200, the workability is deteriorated and the original performance is difficult to be exhibited. The overall Mooney viscosity is 80-1
A range of 50 is preferred. Further, this composition has a Tg measured by DSC in the range of −40 to −10 ° C. and two regions of −70 ° C. or lower in a blended state so as to be a vulcanized rubber compound having a microphase separation. There is a need.
The component (A) and the component (B) of the composition of the present invention are systems that undergo microphase separation, but the Tg after forming a composition may change as compared with the case where they are used alone. However, even in that case, the composition has T measured by DSC in the above two temperature regions.
Must indicate g.

The rubber composition of the present invention can be put to practical use as an oil-extended rubber by adding 5 to 100 parts by weight of the extender oil for rubber to 100 parts by weight of the rubber composition, as is done in general rubber. It is possible. When the Mooney viscosity of the rubber composition is 80 or more, it is preferable to use an oil-extended rubber in order to improve processability. The oil-extended Mooney viscosity (ML1 + 4, 100 ° C.) of the oil-extended rubber is preferably in the range of 30-80. As the extender oil used, aromatic type, naphthene type and paraffin type are used.
Of these, aromatic extender oils are preferable. When the oil-extended polymer is used, the Tg of the rubber composition of the present invention changes depending on the amount of the extender oil, as is known for general oil-extended polymers. It should be noted that this is a weight average value of Tg of.

Next, a method for producing the rubber composition of the present invention will be described. SBR and (B) of these (A) components
The component BR or SBR is n-butyllithium as a polymerization catalyst in an inert hydrocarbon solvent system such as pentane, hexane, benzene, toluene and cyclohexane.
It is a rubber-like polymer obtained by randomly copolymerizing styrene and butadiene or polymerizing butadiene in the temperature range of 30 to 150 ° C. using an organic lithium compound such as sec-butyllithium. In the case of SBR, the styrene block rate is 10% by weight or less. The styrene block rate is measured by a decomposition method using osmic acid or an ozone decomposition method.

A small amount of a polar compound such as ethers or amines is added in order to adjust the amount of vinyl bonds in the microstructure of the butadiene portion to a predetermined amount. During or after the polymerization, silicon tetrachloride, tin tetrachloride, polyester, polyepoxide,
It is also possible to form a branched polymer by adding a functional compound such as a benzophenone compound, a cyclic amide or a cyclic imide to the system and reacting it with an active lithium terminal, or a terminal functional group-containing polymer. Branched polymers and polymers containing terminal functional groups can also be used in the present invention by taking advantage of their characteristics.

The polymer production process may be a batch process or a continuous process. S of component (A) and component (B)
BR, molecular weight distribution of BR (Mw / M measured by GPC
n) is preferably in the range of 1.05 to 3.0.
A method in which the component (A) and the component (B) are separately polymerized and oil-extended in some cases to remove the solvent to form a rubber-like polymer, which is mechanically blended when used as a rubber composition,
The rubber composition of the present invention can be obtained by any method of blending the polymer solutions of the component (A) and the component (B) and then removing the solvent. The component (A) and the component (B) of the present invention are essentially a blend system that causes microphase separation, but it is preferable to blend the polymer solutions with each other because a uniform microphase separation morphology is exhibited.

The rubber-like polymer composition of the present invention is kneaded with carbon black, rubber chemicals and the like by using an internal mixer or a mixing roll, and further compounded with a vulcanizing agent such as sulfur and a rubber chemical. After molding, 140-18
It exhibits its performance in the state of a vulcanized rubber compound which is vulcanized at a temperature of 0 ° C. and is used for a tire tread. Carbon black is used as a reinforcing agent and contributes to the improvement of strength and abrasion resistance. As the carbon black to be used, various ones can be used, but those having an iodine adsorption amount of 80 mg / g or more and a dibutyl phthalate oil absorption amount of 100 ml / 100 g or more are preferable, and examples thereof include N330, N339, N351, N22
0, N234, N110 and the like. The amount of carbon black is 40 to 1 per 100 parts by weight of the rubbery polymer.
50 parts by weight are commonly used.

Next, an extender oil for rubber is used in the rubber-like polymer composition of the present invention, and is mixed in an amount of 5 to 100 parts by weight per 100 parts by weight of the rubber-like polymer. It is preferable that the extender oil for rubber is used as an oil-extended polymer in advance by including a certain amount in the rubber composition because the compounding agent can be dispersed well. As the extender oil, mainly aromatic ones are used. Further, as the vulcanizing agent system, sulfur and a vulcanization accelerator are used in the range of about 0.5 to 5.0 parts by weight per 100 parts by weight of the rubber-like polymer. Further, zinc white, stearic acid, a vulcanization aid, an antiaging agent, and a processing aid are used as necessary as a rubber chemical.

Further, if the original performance of the rubbery polymer composition of the present invention is not significantly impaired, NR, SB
It is possible to blend a small amount of rubber such as R and BR. The rubber-like polymer of the present invention is preferably used in a tread compound for high-performance tires and all-season tires that require low-temperature performance in the form of a vulcanized rubber compound containing carbon black. Applications and anti-vibration rubber, belts,
It can also be applied to industrial products and footwear by taking advantage of its characteristics.

[0035]

EXAMPLES Examples and comparative examples will be shown below. These are illustrative of the invention and not limiting the scope. In the following Examples and Comparative Examples, the SBRs of Samples A1 to A18 shown in Tables 1 and 2 were used as the (A) component of the rubbery polymer composition of the present invention, and the SBRs of Samples B1 to B9 shown in Table 3 were used. BR or SBR was used as the component (B) of the rubbery polymer composition of the present invention. Among the rubbery polymers of these samples, samples A6 and A7 are SBR obtained by emulsion polymerization, and samples B5 and B6 are high cis BR.
However, all other samples are SBR or BR obtained by random copolymerization of styrene and butadiene or polymerization of butadiene in a cyclohexane solvent using a lithium catalyst. These are all GPC
The value of Mw / Mn measured in 1. is 1.9 to 2.7, and in the case of SBR, long-chain styrene (S11 or more) measured by the ozone decomposition method is 5% by weight or less. The measured values of the polymer structure in the table are the values before the addition of the aromatic oil. Except for samples A6, A7, B5, and B6, all were 3 per 100 parts by weight of the rubber-like polymer.
7.5 parts of aromatic oil were added. Using these samples, a rubber composition was prepared by blending the oil-extended polymer solution or the solvent-removed oil-extended polymer at a predetermined ratio, and using the tread formulation for high performance tire application shown in Table 4, B A rubber compound containing carbon black was prepared using a type Banbury mixer, and then the vulcanizing agent and vulcanization accelerator shown in Table 4 were added with an 8-inch mixing roll for testing.
This compound was molded into a predetermined shape and vulcanized in a mold of a vulcanizing press at 160 ° C. for 20 minutes to obtain a test piece.

The measurement of the polymer structure and the evaluation of the performance of the vulcanized rubber compound were carried out as follows. ○ Microstructure of bound styrene and butadiene moieties: Measure the spectrum of the carbon disulfide solution of the sample using an infrared spectrophotometer and calculate by the method of Hampton. ○ Tg and ΔTg: using DSC, temperature rising rate of 10 ° C
Measured in minutes.

Tg is the extrapolation start temperature (On set po)
int) and ΔTg are the extrapolation start temperature and the extrapolation end temperature (En
d point). ○ Tensile strength: According to JIS-K-6301. Tan δ (0 ° C.) and E ′ (0 ° C.): Using a viscoelasticity spectrometer manufactured by Iwamoto Seisakusho, sample shape 5 mm × 3
Measured at 0 mm x 2 mm, initial load 300 g, dynamic strain ± 1%, frequency 10 Hz, temperature 0 ° C.

A large value of Tan δ (0 ° C.) gives good wet grip performance. Good ice grip performance with small E '(0 ° C) value. ○ Embrittlement temperature: Using a DuPont type falling weight impact tester, the breaking temperature was measured under the conditions of a falling weight load of 1000 g, a drop height of 30 cm, and a hammer with a spherical 1/4 inch φ. 25 cooled to a specified temperature
A sheet of mm x 25 mm x thickness 2 mm is placed on a cylinder with an inner diameter of 10 mmφ and an impact test is performed.

Gutrich heat generation: Goodrich flexometer used. 1800 rpm, stroke 0.225 inch, load 55 pounds, starting temperature 50 ° C,
Measure the difference ΔT between the temperature after 20 minutes and the starting temperature. ○ Impact resilience 70 ° C: 70 according to JIS-K-6301
Measure the sample heated to ℃.

Abrasion resistance: Measured using a pico abrasion tester. The larger the index display, the better.

[0041]

Examples 1 and 2 and Comparative Examples 1 to 10 Using the rubber-like polymer composition limited in the present invention shown in Table 5 and the rubber-like polymer composition for comparison, vulcanization was carried out with the composition shown in Table 4. A rubber composition was prepared and the performance was measured. The results are shown in Table 5. The compounds of Comparative Examples 7 to 10 of Table 5 which were used alone were found to have better ice grip properties [E '(0 ° C) as the wet grip properties [the larger the value in Tan δ (0 ° C), the better]. It is clear that the smaller the value is, the better], and the low-temperature fracture performance (the lower the embrittlement temperature, the better) becomes worse. In particular, the emulsion-polymerized SBRs of Comparative Examples 9 and 10 have poor ice grip properties.

On the other hand, in Examples 1 and 2 according to the present invention, the wet grip property, the ice grip property, the low temperature destruction performance, the low heat buildup property (the smaller ΔT is the better),
Impact resilience (larger is better), abrasion resistance (larger is better)
Is well balanced. Further, Comparative Examples 2 and 3 are rubber compounding compositions comprising SBR having a Tg of −30 ° C. or less and polybutadiene, which is a conventionally improved technique, but these have a balance between wet grip performance and low temperature rupture property according to the present invention. Not much improved.

Further, when high cis polybutadiene which does not correspond to the limitation of the present invention is used as the component (B) shown in Comparative Examples 1 and 4, there is little improvement effect on wet grip characteristics and low temperature fracture performance.

[0044]

Examples 1 to 3 and Comparative Examples 7, 8, 11 to 16 Table 6
A vulcanized rubber composition having the composition shown in Table 4 is prepared by changing the Tg of the component (A) shown in Table 1 below and using the rubber-like polymer composition limited in the present invention and the rubber-like polymer composition for comparison. Then, the performance was measured. The results are shown in Table 6. Comparative Examples 7, 8, 13
Nos. 16 to 16 are formulations using SBR alone. In comparison with these, the compositions in which the Tg of the component (A) of Examples 1 to 3 is within the limits of the present invention have wet grip characteristics, ice
The balance of grip properties, low-temperature destructive performance, low heat build-up, impact resilience and wear resistance has been greatly improved.

In Comparative Example 11 in which the Tg of the component (A) is lower than the limit of the present invention, the wet grip property is inferior. On the other hand, Comparative Example 12 in which the Tg of the component (A) is higher than the limit of the present invention.
Has inferior ice grip properties, low-temperature breaking performance, low heat build-up and impact resilience.

[0046]

Examples 1, 4 to 6 and Comparative Examples 1, 17 to 20 Table 7
In Table 4, the Tg of the component (B) and the structural composition of the polymer shown in Fig. 4 are changed, and the rubber-like polymer composition limited in the present invention and the rubber-like polymer composition for comparison are used. A sulfur rubber composition was prepared and the performance was measured. The results are shown in Table 7.
Shown in. The compositions in which the Tg of the component (B) of Examples 1, 4 to 6 and the structural composition of the polymer are within the limits of the present invention have wet grip characteristics, ice grip characteristics, low temperature rupture performance, low heat buildup, and repulsion. Good balance of elasticity and wear resistance.

The compositions using high cis BR as the component (B) in Comparative Examples 1 and 17 have poor wet grip properties. The compositions in which the Tg of the component (B) of Comparative Examples 18 to 20 is higher than the limit of the present invention have little effect of improving the low temperature fracture performance.

[0048]

Examples 7 to 10 and Comparative Examples 8, 21, and 22 Rubber-like polymer compositions limited in the present invention by changing the weight ratio of the components (A) and (B) shown in Table 8 and for comparison. Using the rubber-like polymer composition of No. 1, a vulcanized rubber composition having the composition shown in Table 4 was prepared, and the performance was measured. The results are shown in Table 8. The compositions of Examples 7-10 of the present invention in the limited range were wet.
Grip characteristics, ice grip characteristics, low temperature destruction performance,
Good balance of low heat build-up, impact resilience and abrasion resistance.

In Comparative Example 21, the amount of the component (B) was less than the limited amount, and the effect of improving the low temperature breaking performance and the ice grip property was hardly seen. In Comparative Example 22, the amount of the component (B) is more than the limited amount, and the wet grip property and the strength are poor.

[0050]

Examples 2, 11 to 15 and Comparative Examples 23 to 27 Table 9
By changing the polymer composition and Tg of the component (A) shown below,
Using the rubber-like polymer composition limited in the present invention and the rubber-like polymer composition for comparison, a vulcanized rubber composition having the composition shown in Table 4 was prepared and the performance was measured. The results are shown in Table 9. .. The compositions of Examples 2, 11 to 15 in the limited range of the present invention have a good balance of wet grip properties, ice grip properties, low temperature rupture performance, low heat build-up, impact resilience, and abrasion resistance.

In Comparative Example 23, the vinyl content of SBR as the component (A) was lower than the limit of the present invention, and the low temperature breaking performance, ice
At the same time there is little improvement effect of grip characteristics, low heat generation,
Poor impact resilience. In Comparative Example 24, the vinyl content of SBR as the amount of the component (A) is higher than the range of the limitation of the present invention and the compatibility with the component (B) is good, so that the balance between the wet grip property and the low temperature fracture performance is poor.

In Comparative Example 25, the amount of the bound styrene of the SBR as the amount of the component (A) was lower than the range of the limitation of the present invention and the compatibility with the component (B) was good, so that the wet grip property and the low temperature rupture property were The balance is poor. In Comparative Example 26, the amount of the bound styrene of the SBR as the component (A) is higher than the range of the limitation of the present invention, and the effect of improving the low temperature breaking performance and the ice grip property is small, and at the same time, the low heat buildup property and the impact resilience are inferior.

In Comparative Example 27, the Tg of the component (A) is lower than the limit range of the present invention, and the wet grip property is poor.

[0054]

[Table 1]

[0055]

[Table 2]

[0056]

[Table 3]

[0057]

[Table 4]

[0058]

[Table 5]

[0059]

[Table 6]

[0060]

[Table 7]

[0061]

[Table 8]

[0062]

[Table 9]

[0063]

As described above, the rubber-like polymer composition of the present invention, when used as a vulcanized rubber composition in a tire tread, has good wet grip characteristics, ice
A rubber-like polymer composition exhibiting grip properties, low-temperature rupture performance, low heat build-up, impact resilience, and wear resistance, which is suitable for use in high-performance tires for cold regions where low-temperature performance is required, and is suitable for all-season tires. Is.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between Tan δ (frequency = 10 Hz) -temperature of the vulcanized rubber compound of Example 1.

Claims (1)

[Claims] 1. A (A) component which is a styrene-butadiene random copolymer polymerized by an organolithium compound catalyst in an inert solvent, wherein (1) the glass transition temperature (Tg) measured by DSC is-. Three
0 to -10 ° C (2) Weight ratio of bound styrene / bound butadiene is 30
/ 70 to 50/50 (3) The vinyl bond content of the microstructure of the butadiene portion is 2
5-50 mol% (4) Mooney viscosity (ML1 + 4,100 ° C) is 80-
40 to 85% by weight of a rubbery polymer of 200 and a polybutadiene or a styrene-butadiene random copolymer polymerized by an organolithium compound catalyst in an inert solvent as the component (B), (1) DSC Glass transition temperature (Tg) measured by
00-75 ° C (2) Weight ratio of bound styrene / bound butadiene is 0 /
100 to 10/90 (3) Mooney viscosity (ML1 + 4, 100 ° C) is 30 to
200 to 60% by weight of the rubbery polymer, and the total weight ratio of bound styrene / bound butadiene is 18/8.
2-35 / 65, Mooney viscosity (ML1 + 4,100
C) is 80 to 200, and Tg measured by DSC is -40.
The rubbery polymer composition is in the range of from -10 ° C to -70 ° C.