Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2002-05-20
2004-08-17
Lu, Caixia (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S313000, C525S315000, C525S256000, C525S258000, C525S259000
Reexamination Certificate
active
06777499
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to multiblock interpolymers of conjugated diene and monovinyl aromatic monomer and processes for the preparation thereof. More particularly, the present invention relates to multiblock interpolymers having the following symmetric structures:
Y-X-Y
wherein Y represents a block of a random copolymer of conjugated diene and monovinyl aromatic monomer; and
X represents a block of butadiene homopolymer, a block of isoprene homopolymer, or a block of butadiene/isoprene copolymer.
BACKGROUND OF THE INVENTION
Generally, representative block interpolymers based on butadiene, isoprene and styrene are SBS and SIS, wherein SBS is butadiene/styrene triblock copolymers (wherein B represents polybutadiene block and S represents polystyrene block), and SIS is isoprene/styrene triblock copolymers (wherein I represents polyisoprene block and S represents polystyrene block). By employing difunctional lithium based initiators and changing the charging orders of butadiene, isoprene and styrene, block interpolymers having various different structures can be obtained. Such block interpolymers comprise those having the following symmetric structures: (1) S-I-B-I-S (wherein butadiene, isoprene and styrene are charged sequentially); (2) S-B-I-B-S (wherein isoprene, butadiene and styrene are charged sequentially); (3) S-I-BI-B-BI-I-S (wherein butadiene and isoprene are charged simultaneously at first, and then styrene is charged); (4) S-BS-B-I-B-BS-S (wherein isoprene is charged at first, and then butadiene and styrene are charged simultaneously); (5) S-IS-I-B-I-IS-S (wherein butadiene is charged at first, and then isoprene and styrene are charged simultaneously); (6) S-IS-I-BI-I-BI-I-IS-S (wherein butadiene, isoprene and styrene are charged simultaneously), in the above formula, S represents a polystyrene block, B represents a polybutadiene block, I represents a polyisoprene block, BI represents a block of tapered copolymer of butadiene and isoprene, BS represents a block of tapered copolymer of butadiene and styrene, and IS represents a block of tapered copolymer of isoprene and styrene.
U.S. Pat. No. 5,100,965 to Hsu et al. disclosed a process to synthesize polymers having high trans microstructure content of about 60% to about 85%. The polymers obtained therefrom include high trans-1,4-polybutadiene, styrene-isoprene-butadiene terpolymers with high trans-1,4-polybutadiene microstructure, high trans-isoprene-butadiene copolymers and styrene-butadiene copolymers having high trans-1,4-polybutadiene microstructure. As is know in the art, trans-1,4-polybutadiene is not a rubber, but a thermoplastic resin by virtue of its high level of crystallinity. The high trans styrene-butadiene, styrene-isoprene-butadiene, isoprene-butadiene copolymers prepared by the process in '965 patent all have high level of crystalline structure and have melting points within the range of about −20° C. to about 40° C. As stated in column 13 of '965 patent, though the segmented copolymers of its invention can be used to make tire tread compounds without the need to blend additional rubbers therein, it is desirable, in many cases, to blend the segmented copolymers with one or more additional rubbers, such as natural rubber or styrene-butadiene rubber, to attain the desired performance characteristics for the tire tread compound, such as good rolling resistance, tear resistance, traction, tread wear characteristics and low temperature properties. In fact, such kind of material is seldom used alone as tire rubber. Also the glass transition temperature of the high trans styrene-butadiene, styrene-isoprene-butadiene, isoprene-butadiene copolymers prepared by the process in '965 patent is from about −60° C. to about −95° C. varying with their monomeric makeup. Such kind of materials cannot be of wide glass transition zone, instead, exhibit narrow glass transition zone. It is well known that wide glass transition zone is indicative of an integrated rubber of excellent property balance.
The preparation process disclosed '965 patent needs to utilize a composite initiating system of complicated composition. Besides at least one organolithium initiator, an organoaluminum compound, a barium alkoxide and a lithium alkoxide are necessarily used in the initiating system.
U.S. Pat. No. 5,070,148 to Hsu et al. disclosed a rubber polymer for use in making tire treads, which is prepared by utilizing organo monolithium compounds. The rubber polymer is only a two-segment copolymer and of asymmetric structure. As stated in the patent, the object of its invention is to provide a tire tread material exhibiting excellent combination of wet skid resistance and low rolling resistance that is highly desirable for tires. It is well known in the art that low tan delta value at 60° C. is indicative of good rolling resistance of tire treads and high tan delta value at 0° C. is indicative of good traction characteristic (wet skid resistance). The loss angle tan delta at 60° C. reported in Example 1 of the '148 patent is 0.130; its loss angle tan delta at 0° C. reported in Example 1 is 0.306.
The object of the present invention is to provide novel multiblock interpolymers of conjugated diene and monovinyl aromatic monomer, which have in the same molecule both a rubber block of random copolymer of conjugated diene and monovinyl aromatic monomer and a rubber block selected from blocks of butadiene homopolymer, isoprene homopolymer and butadiene/isoprene copolymer, and hence possess excellent properties of the both two kinds of rubbers.
The inventive multiblock interpolymers are energy-saving rubber materials for using as tire tread rubber, which have very low loss angle tan delta value at 60° C. and thus undergo very low energy loss. Also, such multiblock interpolymers all exhibit wide glass transition zone indicative of an integrated rubber of excellent property balance. Further, such multiblock interpolymers contain no considerable crystalline structure and thus can be used alone as tire tread materials, without the need to blend with one or more additional rubbers to attain desired property balance. The present inventive rubber materials have excellent balance of good wet skid resistance and very low rolling resistance, as well as good low temperature properties, and thus are integrated rubber of excellent comprehensive properties.
Another object of the present invention is to provide processes for the preparation of the novel multiblock interpolymers, it can prepare the above integrated rubber material in situ in a single reactor instead of physically blending.
The present preparation process utilizes simple one-component initiating system, without the need of adding other components, such as an organoaluminum compound, a barium alkoxide and a lithium alkoxide, as coinitiator.
SUMMARY OF THE INVENTION
Therefore, in one aspect the present invention relates to multiblock interpolymers having the following symmetric structures:
Y-X-Y
wherein Y represents a block of a random copolymer conjugated diene and monovinyl aromatic monomer, wherein the content of the 1,2- or 3,4-addition polymerization structure of the conjugated diene in block Y is from 10 to 50 percent by weight, based on the total weight of the units derived from the conjugated diene in block Y; and
X represents a block of butadiene homopolymer, a block of isoprene homopolymer, or a block of butadiene/isoprene copolymer, wherein the content of 3,4-addition polymerization structure of isoprene in block X is, based on the total weight of the units derived from the isoprene in block X, from 6 to 20 percent by weight, and/or the content of 1,2-addition polymerization structure of butadiene in block X is, based on the total weight of the units derived from the butadiene in block X, from 6 to 20 percent by weight.
In another aspect, the present invention relates to processes for the preparation of the present multiblock interpolymers by anionic polymerization.
In still another aspect, the present invention rela
Ding Jian
Gu Mingchu
Hong Dingyi
Li Yang
Lu Xingjun
China Petroleum & Chemical Corporation
Christie Parker & Hale LLP
Lu Caixia
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