Hindered amine adducts for polyurea systems

Details Hindered amine adducts for polyurea systems Hindered amine adducts for polyurea systems

1999-12-07

2002-04-09

Sergent, Rabon (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From reactant having at least one -n=c=x group as well as...

C427S180000, C427S202000, C427S385500, C528S059000, C528S060000, C528S061000, C528S068000, C528S076000, C528S077000, C528S084000

Reexamination Certificate

active

06369189

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to polyurea polymers, particularly polyurea polymers containing hindered amine adducts, and more particularly polyurea polymers containing hindered amine adducts suitable for coatings.
BACKGROUND OF THE INVENTION
Synthetic polymers have an enormous impact on our day-to-day lives. Polymers have a variety of uses ranging from films and foams to molded plastics and adhesives, just to name a few. One of the most popular uses for polymer compositions is as a coating material. Both one- and two-component coating compositions, particularly polyurethane and polyurea based coating compositions, are known.
One-component coating compositions typically contain fully reacted polyurethanes as the binder. One of the many advantages of one-component coating systems is that they provide good adhesion to a substrate. This adhesive property exists because the one-component systems have relatively long dry times that allow for sufficient wetting of the substrate. While the adhesive properties are advantageous, long dry times, however, may make one-component coatings unsuitable for applications that require rapid dry times, for example pavement marking. Additionally, these coatings require large amounts of solvents to reduce their viscosity. There is a growing concern that solvents, particularly the organic solvents often used in one-component systems, may pose severe environmental and occupational safety hazards. Furthermore, one-component systems suffer from poor wear properties because they do not form highly crosslinked coatings.
Two-component compositions often contain a polyisocyanate component in one container and an isocyanate-reactive component in a second container. One such two-component system is a polyurea system. An exemplary polyurea system is disclosed in U.S. Pat. No. 5,218,005 to Zimmerman et al. Zimmerman et al. propose a polyurea system containing polyisocyanate, polyoxyalkylene polyamine, and polyamine adduct. U.S. Pat. No. 5,516,873 to Hicks et al. describes a polyurea system containing polyisocyanate, aldimine, and a compound containing an aspartate group. U.S. Pat. No. 5,559,204 to Squiller et al. discusses a polyurea coating system containing an aldimine/aspartate as the isocyanate-reactive component. U.S. Pat. No. 5,616,677 to Primeaux, II et al. proposes an aliphatic spray polyurea elastomer containing an aliphatic isocyanate, an amine-terminated polyoxyalkylene polyol, and a cycloaliphatic diamine chain extender.
Polyurea systems may provide highly crosslinked coatings that do not require large amounts of solvents. Extensive crosslinking may give these coatings excellent physical properties, including elongation and abrasion resistance. Additionally, the two components may react very quickly, with typical gel and dry times measured in seconds. Such rapid dry times appear to make these coatings suitable for applications like pavement marking. However, the reaction between the two components may actually occur too quickly. Due to the very rapid cure speed, polyurea systems must be applied with specialized application equipment, in which the two components are mixed immediately prior to the application. Even with the specialized equipment, the acceptance of polyurea systems has been low due to the application difficulties and performance problems. For instance, in coating applications polyureas have been reported to cure before the substrate is adequately wetted, yielding a film with poor adhesion.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide improved polymeric compositions that combine the exceptional properties of two-component polyurea systems, including rapid cure rate, with the excellent adhesive properties of one-component polyurethane systems.
It is another object of the present invention to provide an isocyanate-reactive component for use in such improved polymeric systems.
It is yet another object of the present invention to provide methods of forming such improved polymeric systems.
It is still another object of the present invention to provide methods of applying such improved polymeric systems to a substrate.
These and other objects, features and advantages are achieved by the various compositions and methods of the present invention. In one embodiment, a polymeric composition includes an isocyanate component and an amine component, which includes:
where R
1
represents a hydrocarbon radical, X represents an organic group, and a is an integer.
In another embodiment, a polymeric composition may include from about 5 to about 50 weight percent of an isocyanate component, and from about 50 to about 95 weight percent of an amine component including:
where R
1
represents a hydrocarbon radical, X represents an organic group, and a is an integer.
In yet another embodiment, an amine composition may include from about 30 to about 100 weight percent of a compound of Formula I,
and from about 0 to about 70 weight percent of a compound of Formula II,
where R
1
and R
2
represent hydrocarbon radicals, X and Y represent organic groups, and a and b are both integers.
In further embodiments, methods of forming compositions of the present invention and of applying polymeric compositions of the present invention to substrates are provided.
By utilizing at least one hindered amine adduct as the amine component, polymeric compositions of the present invention combine the exceptional properties of a two-component polyurea system, including rapid cure time, with the excellent adhesive qualities of a one-component polyurethane system.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention will now be described in greater detail with reference to the preferred embodiments which follow. It should be appreciated, however, that these embodiments are for illustrative purposes only, and are not meant to limit the invention as defined by the claims.
Polymeric compositions of the present invention may be formed by reacting an isocyanate component with an amine component. The isocyanate component used in the polymeric composition may be selected from isocyanates known in the art of polyurethane and polyurea chemistry including any of the aliphatic, cycloaliphatic, araliphatic or aromatic polyisocyanates. Examples of particularly suitable polyisocyanates include monomeric isocyanates, isocyanate functional prepolymers, isocyanate functional adducts, and mixtures thereof.
Examples of suitable monomeric isocyanates include 1,6 hexamethylene diisocyanate, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, isophorone diisocyanate, bis-(4-isocyanatocyclohexyl)-methane, 2,4-diphenyl-methane diisocyanate, 4,4′-diphenyl-methane diisocyanate, 1,1′-methylenebis(4-isocyantocyclohexane), trimethyl-hexamethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,12-dodecamethylene diisocyanate, 1-isocyanato-2-isocyanatomethyl cyclopentane, cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, 2,4′-dicyclohexyl-methane diisocyanate, bis-(4-isocyanato-3-methylcyclohexyl)-methane, 1,3-bis-(isocyanatomethyl)-cyclohexane, 1,4bis-(isocyanatomethyl)-cyclohexane, &agr;,&agr;,&agr;′,&agr;′-tetramethyl-3-xylylenediisocyanate, &agr;,&agr;,&agr;′,&agr;′-tetramethyl-1,4-xylylenediisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-toluylene diisocyanate, 2,6-toluylene diisocyanate, 2,4-hexahydrotoluylene diisocyanate, 2,6-hexahydrotoluylene diisocyanate, 1-isocyanato-1-methyl-4(3)-isocyanatomethyl cyclohexane, and 1,5-diisocyanato naphthalene and mixtures thereof.
The isocyanate component may also be a monomeric isocyanate material that is chain extended by an alcohol to form an isocyanate functional prepolymer. Examples of suitable functional prepolymers can be prepared by reacting a monomeric isocyanate with a low molecular weight alcohol, to form for example prepolymers based on isophorone diisocyanate and trimethylol propane, prepolymers of isophorone diisocyanate and pentaerythritol, and prepolymers of isophorone diisocyanate and hexane diol. The alcoh

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