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
1995-03-07
2003-02-25
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S331700, C525S331900, C525S332800
Reexamination Certificate
active
06525142
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to novel monohydroxylated diene polymers which are suitable for use in a variety of applications including adhesives, sealants, coatings, modification of other polymers or asphalt, etc., as well as to be further functionalized to produce useful polymers. More specifically, the invention relates to particular epoxidized monohydroxylated polydiene polymers and their epoxidized derivatives.
Monohydroxylated polydienes are known. Most of these polymers are homopolymers of one diene or another. For example, monohydroxlated polybutadienes are known in the art for use in adhesive formulations. U.S. Pat. No. 4,242,468 describes solventless polyurethane coatings having improved flexibility resulting from incorporation of monohydroxylated polybutadienes. Epoxidized versions of hydroxylated polybutadienes are known as well. Low viscosity epoxidized polydiene polymers are also known, especially for use in adhesives. Such polymers are described in commonly assigned U.S. Pat. Nos. 5,229,464 and 5,247,026.
While the low viscosity polymers of the prior art are useful in applications where aliphatic epoxies are generally employed., they suffer the disadvantage of not being reactive via a broader class of chemistry. Further, epoxidation is costly and many examples of the prior art required high levels of epoxy functionality to be of utility. Incorporation of a more economical moiety which would provide the same or broader chemical utility is highly desirable. The present invention provides polymers which overcome the disadvantages of the aforementioned limited chemical reactivity. Further, in applications requiring epoxy functionality for chemical compatibility these polymers reduce the necessary epoxy levels.
SUMMARY OF THE INVENTION
This invention is a monohydroxylated polydiene polymer which is comprised of at least two polymerizable ethenically unsaturated hydrocarbon monomers wherein at least one is a diene monomer which yields unsaturation suitable for epoxidation. The invention also contemplates partially unsaturated and/or epoxidized derivatives of these novel monohydroxylated polydiene polymers. The hydroxylated polymers are preferably block copolymers of at least two diene monomers, preferably isoprene and butadiene, and, optionally, a vinyl aromatic hydrocarbon wherein a hydroxyl group is attached at one end of the polymer molecule. These polymers may be hydrogenated or unhydrogenated but they are preferably epoxidized.
The preferred monohydroxylated polydiene polymer of the present invention has the structural formula
(HO)
x
—A—S
z
—B—(OH)
y
(I)
wherein A and B are polymer blocks which may be homopolymer blocks of conjugated diolefin monomers, copolymer blocks of conjugated diolefin monomers, or copolymer blocks of diolefin monomers and monoalkenyl aromatic hydrocarbon monomers. These polymers may contain up to 60% by weight of at least one vinyl aromatic hydrocarbon, preferably styrene. Generally, it is preferred that the A blocks should have a greater concentration of more highly substituted aliphatic double bonds than the B blocks have. Thus, the A blocks have a greater concentration of di-, tri-, or tetra-substituted unsaturation sites (aliphatic double bonds) per unit of block mass than do the B blocks. This produces a polymer wherein the most facile epoxidation occurs in the A blocks. The A blocks have a molecular weight of from 100 to 6000, preferably 500 to 4,000, and most preferably 1000 to 3000, and the B blocks have a molecular weight of from 1000 to 15,000, preferably 2000 to 10,000, and most preferably 3000 to 6000, S is a vinyl aromatic hydrocarbon block which may have a molecular weight of from 100 to 10,000, x and y are 0 or 1. Either x or y must be 1, but only one at a time can be 1, z is 0 or 1. Either the, A or the B block may be capped with a miniblock of polymer, 50 to 1000 molecular weight, of a different composition, to compensate for any initiation, tapering due to unfavorable copolymerization rates, or capping difficulties. These polymers may be epoxidized such that they contain from 0.1 to 7.0 milliequivalents (meq) of epoxy per gram of polymer.
DETAILED DESCRIPTION OF THE INVENTION
Polymers containing ethylenic unsaturation can be prepared by anionically copolymerizing one or more olefins, particularly diolefins, by themselves or with one or more alkenyl aromatic hydrocarbon monomers. The copolymers may, of course, be random, tapered, block or a combination of these.
Diene containing polymers, having residual unsaturation suitable for epoxidation, may also be obtained by other means of polymerization, such as by cationic polymerization or free radical polymerization. Using cationic polymerization, monomers such as substituted 1-butenes, 1-pentenes and dienes such as isoprene and butadiene can be copolymerized. Like anionic polymerization, living cationic polymerization allows the copolymers to be block copolymers such that the residual diene double bond can be localized within the polymer. Dienes may be polymerized together with acrylic monomers by initiation with a free radical initiator, such a peroxide or AIBN. For pressure sensitive adhesive applications, monomers such as n-butyl acrylate, 2-ethyl-hexyl acrylate and isoprene may be used, and other modifying monomers, such as acrylic acid or 2-hydroxy-ethyl acrylate may also be used. Other polymerization methods including coordination/insertion mechanisms such as Ziegler-Natta polymerizations, metallocene polymerizations, and metathesis polymerizations can also be used to make polymers such as these.
The polymers containing ethylenic unsaturation or both aromatic and ethylenic unsaturation may be prepared using anionic initiators or polymerization catalysts. Such polymers may be prepared using bulk, solution or emulsion techniques. When polymerized to high molecular weight, the polymer containing at least ethylenic unsaturation will, generally, be recovered as a solid such as a crumb, a powder, a pellet or the like. When polymerized to low molecular weight, it may be recovered as a liquid.
In general, when solution anionic techniques are used, copolymers of conjugated diolefins, optionally with vinyl aromatic hydrocarbons, are prepared by contacting the monomer or monomers to be polymeized simultaneously or sequentially with an anionic polymerization initiator such as group IA metals, their alkyls, amides, silanolates, napthalides, biphenyls or anthacenyl derivatives. It is preferred to use an organo alkali metal (such as sodium or potassium) compound in a suitable solvent at a temperature within the range from about −150° C. to about 300° C., preferably at a temperature within the range from about 0° C. to about 100° C. Particularly effective anionic polymerization initiators are organo lithium compounds having the general formula:
RLi
n
wherein R is an aliphatic, cycloaliphatic, aromatic or alkyl-substituted aromatic hydrocarbon radical having from 1 to about 20 carbon atoms and n is an integer of 1 to 4.
Conjugated diolefins which may be polymerized anionically include those conjugated diolefins containing from about 4 to about 24 carbon atoms such as 1,3-butadiene, isoprene, piperylene, methylpentadiene, phenyl-butadiene, 3,4-dimethyl-1,3-hexadiene, 4,5-diethyl-1,3-octadiene and the like. Isoprene and butadiene are the preferred conjugated diene monomers for use in the present invention because of their low cost and ready availability. Alkenyl (vinyl) aromatic hydrocarbons which may be copolymerized include vinyl aryl compounds such as styrene, various alkyl-substituted styrenes, alkoxy-substituted styrenes, vinyl napthalene, alkyl-substituted vinyl napthalenes and the like.
The monohydroxylated polydienes are synthesized by anionic polymerization of conjugated diene hydrocarbons with lithium initiators. This process is well known as described in. U.S. Pat. No. 4,039,593 and Re. No. 27,145 which descriptions are incorporated herein by reference. Polymerization commences with a monolithium initiator which builds a living polymer ba
Erickson James Robert
Masse Michael Alan
St. Clair David John
Cain Edward J.
Kraton Polymers U.S. LLC
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