Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2002-04-18
2004-07-06
Harlan, Robert D. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S335000, C526S336000
Reexamination Certificate
active
06759497
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to polymers based on conjugated dienes or on conjugated dienes and vinyl aromatic compounds that are modified by polar groups along the polymer chain and contain a high proportion of cis-position double bonds.
It is known to modify polymers with organic compounds that contain in the molecule at least one polar group and a group capable of reacting with the polymer anions. The modification of the polymers is normally carried out by first of all metallizing polymers that contain active hydrogen atoms and then reacting them with the aforementioned organic compounds. Reference may be made in this connection to U.S. Pat. No. 3,925,511, U.S. Pat. No. 4,761,456 as well as U.S. Pat. No. 3,978,161. The polymers modified according to the prior art are preferably used in tire manufacture in order to improve the interaction of the fillers present in the tires with the rubber. A disadvantage of the use of such modified polymers, that have a small content of cis-position double bonds due to the method of their production is that they can be incorporated only with difficulty into rubber mixtures and that the mechanical/dynamical property profile of the rubber molded articles produced thereby is adversely affected compared to the normally used, unmodified polymers such as polybutadienes.
EP 1 022 291 A1 describes modified diene elastomers which, despite having a high cis-content, have a very high gel content due to the method of their production. In addition, the diene elastomers described in EP 1 022 291 A1 are not modified along the chain, but are modified special organosilicon compounds at the end group.
British Patent Application GB 1173508 A discloses the production of homopolymers or copolymers, by, for example, ionic polymerization, and the functionalization thereof, with corresponding organic compounds containing functional groups. The homopolymers or copolymers produced according to this reference have a cis-1,4 content of about 92%. The gel content is higher than 5 wt. % and thus greatly restricts the practical use of such polymers.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to obviate the disadvantages of the hitherto used modified polymers, i.e. to improve their ability to be incorporated into rubber mixtures and to improve the mechanical/dynamical properties of the rubber molded articles produced, as well as their gel content.
The aforementioned disadvantages in the production of rubber molded articles using known modified polymers can now be obviated if modified polymers, that are modified along their polymer chain, i.e. not at their chain end, are used based on conjugated dienes or on conjugated dienes and vinyl-aromatic compounds that contain, inter alia, a high proportion of cis-position double bonds and have a low gel content.
Accordingly, the present invention provides modified polymers, which are modified along their polymer chain and are based on conjugated dienes or on conjugated dienes and vinyl aromatic compounds and have a content of vinyl-aromatic compounds of up to 60 wt. %, a content of cis-position double bonds of ≧92%, a mean molecular weight (M
w
) of 50,000 to 1,500,000 g/mole, a gel content of ≦5% and a degree of modification of 0.05 to 20 wt. %.
DETAILED DESCRIPTION OF THE INVENTION
The modified polymers according to the present invention have a content of cis-position double bonds of preferably ≧95%, and in particular ≧97%, based on the proportion of conjugated dienes in the molecule.
The modified polymers according to the present invention have a mean molecular weight (M
w
) (determined by GPC=gel permeation chromatography) of preferably 200,000 to 700,000 g/mole. The glass transition temperature (T
G
) is −90° to −110° C. and preferably, −95° to −108° C., as determined by DSC.
Suitable conjugated dienes are, for example, 1,3-butadiene, isoprene, piperylene, 1,3-hexadiene, 1,3-octadiene as well as 2-phenyl-1,3-butadiene; 1,3-butadiene is preferred.
Vinyl aromatic compounds which may be copolymerized with the conjugated dienes are, for example, styrene, p-methylstyrene, &agr;-methylstyrene, 3,5-dimethylstyrene, vinylnaphthalene, p-tert.-butylstyrene, divinylstyrene and diphenylethylene; styrene is preferred. The proportion of vinyl aromatic monomers copolymerizable with the conjugated dienes in the corresponding copolymers is preferably 10 to 45 wt. %.
The modified polymers according to the present invention have a gel content of ≦3%, preferably ≦1%, as determined according to ASTM D3616-95 (Standard Test Method for Rubber, Raw-Determination of Gel, Swelling Index, and Dilute Solution Viscosity).
The degree of modification, of the modified polymers according to the present invention, is about 0.08 to 5 wt. %, preferably 0.1 to 2 wt. %, as determined by elemental analysis of the organic compounds used for the modification, that contain polar groups containing elements of main groups III, IV, V, VI or VII of the periodic system of the elements (PSE).
The present invention also relates to a process for producing polymers that are modified along the polymer chain and are based on conjugated dienes or on conjugated dienes and vinyl aromatic compounds and that have the above-mentioned contents of vinyl aromatic compounds, the above-mentioned proportion of cis-position double bonds and the above-mentioned mean molecular weight, gel content and degree of modification, wherein (a) the conjugated dienes or the conjugated dienes and vinyl-aromatic compounds are polymerized at temperatures of −30° to 130° C., in the presence of rare earth metal compounds, and in the presence of an inert, aliphatic solvent, the water content of the reaction mixture being ≦1,000 ppm, and preferably 500 ppm, (b) the resulting polymers containing about 1.0 to 1,000, preferably 1.5 to 100, and more preferably about 2 to 30, mmole/100 g of polymer of active hydrogen atoms are reacted with 0.1 to 200 mmole, based on 100 g of polymer, of organometallic compounds or with the metals themselves, the metals of the organometallic compounds being selected from the group of alkali metals or alkaline earth metals, in the presence of 0.1 to 200 mmole, based on 100 g of polymer, of compounds capable of forming co-ordinate bonds with the metallized polymer anions, at temperatures of 20° to 200° C. and (c) at temperatures of 0° to 200° C., the stabilized polymer anions obtained are reacted with 0.01 to 200 mmole, based on 100 g of polymer, of organic compounds that contain a group capable of reacting with the polymer anions and at least one polar group in the molecule, wherein the polar groups contain elements of main groups III, IV, V, VI or VII of the PSE or combinations thereof, and the groups capable of reacting with the polymer anions are selected from carbonyl groups, acid chloride groups, metal halide groups, sulfenyl groups, sulfonyl groups, aminochloride groups, groups containing reactive double bonds, epoxide groups, isocyanate groups, nitrile groups and organosilicon and organotin groups, in the presence of aprotic, organic solvents.
Suitable organic compounds that preferably contain in the molecule 1 to 5 polar groupings or groups and only one grouping or group that is capable of reacting with the polymer anions and that are suitable for modifying the aforementioned polymers, are preferably those containing boron, silicon, carbon, tin, nitrogen, oxygen, sulfur, fluorine, chlorine and bromine, and in particular silicon, tin, nitrogen, oxygen and chlorine in the polar groups.
The following are, for example, suitable as polar groups: hydroxyl groups, carboxyl groups, amino groups, ester groups, carbonyl groups, halogens, epoxide groups, ether groups, nitrile groups, thioether groups, sulfonic acid ester groups, phosphoric acid and phosphorous acid ester groups, ammonium groups, organotin groups, as well as organosilicon groups, such as open-chain or cyclic siloxane or silane groups. Preferred are ester groups, ammonium groups, amino groups as well as the
Braubach Wilfried
Grün Michael
Knauf Thomas
Bayer Aktiengesellschaft
Gil Joseph C.
Harlan Robert D.
Seng Jennifer R.
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