Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1995-02-16
2001-06-19
Sellers, Robert E. L. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C525S09200D, C525S314000
Reexamination Certificate
active
06248810
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to waterborne dispersions of epoxidized polydiene block polymers. More specifically, the invention relates to waterborne dispersions of such polymers and amino resins which can be crosslinked to make cured films, coatings, adhesives, sealants, caulks, binders and modifiers for asphalt.
Epoxidized polydiene polymers have been disclosed recently in U.S. Pat. Nos. 5,229,464 and 5,247,026. These are relatively low epoxy content polymers. Higher epoxy content polymers are described in copending, commonly assigned United States patent application Ser. No. 228,047, filed Apr. 15, 1994, entitled “Epoxidized Low Viscosity Rubber.” It has been shown that such polymers are useful in high solids, solvent-borne adhesives and coatings and that formulations containing these polymers and a cationic photoinitiator can be cured via ultraviolet radiation. It has also been shown that formulations containing these polymers, a melamine resin, and an acid catalyst can be cured by baking under normal bake conditions.
Although this high solids technology is of great value, it is true that if such polymers could be dispersed in water, the utility of these polymers would be greatly broadened. This would allow preparation of low viscosity, waterborne formulations having very low volatile organic compound (VOC) contents. By adding waterborne epoxidized polydiene polymer dispersions to other water-based products having compatible surfactant systems, these polymers could be used to modify other types of resins and this could be done without concern about phase separation due to incompatibility of the epoxidized polydiene polymers and solvent-based resins.
It is one object of the present invention to provide a crosslinkable waterborne dispersion of epoxidized polydiene polymers and amino resins. Another object of this invention is to provide a method for maldng such crosslinkable waterborne dispersions.
SUMMARY OF THE INVENTION
The present invention provides a water dispersion of a crosslinkable epoxidized polydiene block polymer composition which comprises:
(a) 10 to 65% by weight (% w) of a polydiene block polymer containing at least 5 olefinic epoxy groups per molecule which are sterically hindered and which preferably do not have a significant amount of other functional groups,
(b) 0.2 to 25% w of a compatible amino resin,
(c) 0.1 to 10% w of a nonionic surfactant or an anionic surfactant having a volatile cation, and
(d) the balance water.
In a preferred embodiment of the present invention, the compatible aminoplast is a butylated aminoplast and the surfactant is an anionic surfactant composed of an amine salt of an acid which can be used to catalyze the crosslinldng of the polymer and the aminoplast such as paratoluene sulfonic acid or dodecylbenzene sulfonic acid.
This invention also describes processes for making such crosslinkable waterborne dispersions. One method involves making a hot aqueous solution of the surfactant, adding a mixture of an epoxidized block polymer and a compatible aminoplast to the hot aqueous solution, and then mixing the components under high shear conditions. The preferred method involves mixing together at a temperature of 25 to 90° C. with vigorous agitation an epoxidized polydiene block polymer, an aminoplast, and the desired surfactant, and then adding water to the mixture slowly over a period of at least 15 minutes.
DETAILED DESCRIPTION OF THE INVENTION
The general methods of making block copolymers are reviewed by R. P. Quirk and J. Kim, “Recent Advances in Thermoplastic Elastomer Synthesis,” Rubber Chemistry and Technology, volume 64 No. 3 (1991), which is incorporated herein by reference. Especially useful is the method of sequential anionic polymerization of monomers. The types of monomers that will undergo living polymeriation are relatively limited for the anionic method, with the most favorable being conjugated diolefins and monoalkenyl aromatic hydrocbon monomers. Generally, a hydrogenation step is needed to prepare a saturated polymer. Hence, a polymer of this invention that is both epoxidized and saturated usually requires both an epoxidation and a hydrogenation step. However, polymers made by sequential polymerization of a suitable diolefin monomer and a monomer having only one carbon carbon double bond or by sequential polymerization of two different mixtures (ratios) of such monomers, using either a monofunctional initiator, a monofunctional initiator and a coupling agent, or a multifunctional initiator, may be epoxidized and would not have to be hydrogenated to produce an epoxidized polymer of this invention that is saturated. Preferred polymers for use herein are described in detail in the aforementioned U.S. patents and patent application which are herein incorporated by reference.
The polymers containing olefinic unsaturation or both aromatic and olefinic unsaturation may be prepared using anionic initiators or polymerization catalysts. Such polymers may be prepared using bulk, solution or emulsion techniques. Polymers prepared in solution are preferred for subsequent epoxidation and hydrogenation.
The polymer may be epoxidized under conditions that enhance the epoxidation of the more highly substituted olefinic double bonds, such as by the use of peracetic acid, wherein the rate of epoxidation is generally greater the greater the degree of substitution of the olefinic double bond (rate of epoxidation: tetrasubstituted>trisubstituted>disubstituted>monosubstituted olefinic double bond). If a substantially saturated polymer is desired, the epoxidized polymer may be hydrogenated to remove substantially all remaining olefinic double bonds (ODB) and normally leaving substantially all of the aromatic double bonds. If only substantially saturated interior blocks are desired, the epoxidized polymer may be partially hydrogenated in a selective manner with a suitable catalyst and conditions (like those in Re 27,145, U.S. Pat. No. 4,001,199 or with a titanium catalyst such as is disclosed in U.S. Pat. No. 5,039,755, all of which are incorporated by reference; or by fixed bed hydrogenation) that favor the hydrogenation of the less substituted olefinic double bonds (rate or hydrogenation: monosubstituted>disubstituted>trisubstituted>tetrasubstituted olefinic double bonds) and also leaves aromatic double bonds intact
In general, when solution anionic techniques are used, conjugated diolefin polymers and copolymers of conjugated diolefins and alkenyl aromatic hydrocarbons are prepared by contacting the monomer or monomers to be polymerized simultaneously or sequentially with an anionic polymerization initiator such as group IA metals, their alkyls, amides, silanolates, napthalides, biphenyls and anthracenyl 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, phenylbutadiene, 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. The conjugated diolefins which may be used in the present invention include isoprene (2-methyl-1,3-butadiene), 2-ethyl-1,3-butadiene, 2-propyl-1,3-butadiene, 2-butyl-1,3-butadiene, 2-pentyl-1,3-butadiene(2-amyl-1,3-butadiene),2-hexyl-1,3-butadiene,2-heptyl-1,3-butadiene, 2-octyl-1,3-butadiene,2-nonyl-1,3-bu
Erickson James Robert
St. Clair David John
Haas Donald F.
Sellers Robert E. L.
Shell Oil Company
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