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
2001-09-14
2003-11-11
Short, Patricia A. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S162000, C525S174000, C525S406000, C525S407000, C525S408000, C525S438000, C525S440030, C525S443000, C525S444000, C525S131000
Reexamination Certificate
active
06646049
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to coating compositions, to binders for use in formulating coating compositions, and to methods of making and using such binders and compositions.
More particularly, the present invention relates to binders that are made using one or more hyperbranched polyols as reactive intermediates, to thermoset coating compositions incorporating such binders, and to methods of making and using same.
2. Description of the Background Art
Certain hyperbranched macromolecules are known for use in preparing high-solids coating compositions.
U.S. Pat. No. 5,418,301 to Hult et al. discloses a dendritic macromolecule, which is formed beginning with a central initiator molecule having reactive hydroxyl groups thereon. A monomeric chain extender is attached to each of the reactive hydroxyl groups to form a highly branched structure. A chain stopper molecule may, optionally, be added to the chain extender to further increase the size of the macromolecule, and to terminate the macromolecule-forming reaction.
U.S. Pat. No. 5,663,247 to Sorensen et al. discloses another hyperbranched polyester macromolecule, formed from an epoxide nucleus and hydroxy-functional carboxylic acid chain extenders, and a method of making the hyperbranched macromolecule.
Other polyesters are disclosed in U.S. Pat. Nos. 5,852,162 and 5,869,191.
Some coating compositions, formed with the known linear polyols as reactive intermediates, exhibit some tendency to crack when they are flexed. Such relatively brittle materials are less than optimal for use in making coating compositions that are intended to be applied to automotive bodies or flexible materials, such as resiliently bendable plastics or elastomers. Since modem engineering often combines dissimilar materials such as, e.g., metal and plastics or elastomers into an assembled product to be painted, a need exists for coatings that are useful to paint all of such dissimilar materials.
Many known polyurethane binders may be formed by reacting long-chain linear polyols with isocyanates. Polyurethane coatings may be powder coatings or may be waterborne dispersions. Polyurethane coatings are further divisible into one-component and two-component systems. Various polyurethane and carbamate-containing compositions are disclosed in U.S. Pat. Nos. 4,279,833, 4,791,168, 4,820,830, 5,326,815, 5,373,069, 5,563,208, 5,792,810, 5,945,499, and 5,976,615.
While many different types of coatings are known, the coatings art needs improved coating compositions that are strong and durable, yet which will still have good flexibility and resiliency.
The coatings art also has an ongoing need for coating compositions that will be good bonding substrates, for providing a good surface to receive subsequent repair finishes applied thereto.
Further, the coatings art is continually seeking coating compositions with reduced levels of organic solvents used therein, to minimize the volatile organic content (VOC), while keeping other useful properties, such as viscosity, sprayability, and rheology control for resisting sagging in application thereof, within acceptable ranges.
SUMMARY OF THE INVENTION
The present invention provides a binder comprising: a) a principal resin polyol comprising at least one of a polyester polyol, a polyether polyol, and a polyacrylate; b) a hyperbranched polyol comprising both external and partially embedded hydroxyl groups in the structure thereof; and c) a crosslinker.
The present invention also provides a method of making a coating composition, comprising: a) providing a principal resin polyol as a first reactant, the principal resin polyol comprises at least one of a polyester polyol, a polyether polyol, and a polyacrylate; b) providing an effective amount of a second reactant to the principal resin polyol to form a polyol reaction mixture, wherein the second reactant is a hyperbranched polyol comprises both external and partially embedded hydroxyl groups in its structure; c) providing an effective amount of a polymerization catalyst; d) providing a crosslinker; and e) adding a solvent.
The present invention also provides a method of making a binder comprising: a) providing a principal resin polyol as a first reactant, the principal resin polyol comprises at least one of a polyester polyol, a polyether polyol, and a polyacrylates; b) providing an effective amount of a second reactant to the principal resin polyol to form a polyol reaction mixture, wherein the second reactant is a hyperbranched polyol comprising both external and partially embedded hydroxyl groups in the structure thereof; and c) providing a crosslinker to the reaction mixture.
A thermoset coating composition comprising a solvent and a mixture of: a) a principal resin polyol comprising at least one of a polyester polyol, a polyether polyol, and a polyacrylate; b) a hyperbranched polyol having both external and partially embedded hydroxyl groups in the structure thereof; c) a crosslinker; and d) an effective amount of a polymerization catalyst.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Throughout the following detailed description and in the examples therein, all parts are by weight of the total solids portion of the composition, unless otherwise specified.
The present invention provides a thermosettable binder for a polymeric coating composition and a coating composition made therewith, in which the binder is formed using a hyperbranched polyol as a reactive intermediate. Binders according to the present invention incorporate a principal resin polyol, together with at least one hyperbranched polyol as a reactive intermediate, and at least one crosslinker.
More specifically, a coating composition binder, in accordance with the invention, is a reaction product of
(a) a principal resin polyol that is at least one of a polyester polyol, a polyether polyol, a polyacrylate;
(b) a hyperbranched polyol having both external (principal) and partially embedded (secondary) hydroxyl groups in the structure thereof; and (c) a crosslinker that is at least one of an isocyanate, an isocyanurate, an epoxide, an aminoplast, an anhydride, and the corresponding polyacids of the anhydrides.
Preferably, the principal resin polyol is present in an amount ranging from 0-80 percent of the total solids content of the binder, more preferably between 20-60 percent and most preferably between 30-50%.
Preferably, the hyperbranched polyol is present in an amount ranging from 10-90 percent of the total solids content of the binder, more preferably between 10-60 percent and most preferably between 20-50%.
Preferably, the crosslinker is present in an amount ranging from 10-30 percent of the total solids content of the binder, more preferably between 10-25 percent and most preferably between 10-20%.
Principal Resin Polyol
As noted, a binder according to the invention may include a principal resin polyol that is at least one of a polyester polyol, a polyether polyol, and a polyacrylate.
Examples of polyester and polyether polyols may be found, for example, in U.S. Pat. Nos. 4,216,107, 4,305,861, and 4,582,926, the disclosures of which are incorporated herein by reference. Non-limiting examples of producing the polyester and polyether polyols from these patents are summarized below.
The polyester or polyether polyols can be obtained by catalytic esterification of (a) polyols with carboxylic acid anhydrides to form carboxylic acid half-esters and subsequent (b) oxyalkylation of the carboxylic acid half-esters with alkylene oxides. The carboxylic acid half-esters (a) are first prepared from polyols or polyol mixtures having from 2 to 6 hydroxyl groups, and an organic carboxylic acid anhydride or carboxylic acid anhydride mixture in the presence of a catalyst at temperatures from 50° C. to 240° C. and reaction times of 0.5 to 8 hours. The basic polyol and carboxylic acid anhydride components are thus reacted in such amounts that 1 to 6 moles of carboxylic acid anhydride is present per mole polyol, and 1 to 6 equivalents hydroxyl groups are present per equival
BASF Corporation
Short Patricia A.
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