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
2002-03-11
2003-03-18
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S437000, C525S438000, C524S561000, C524S562000
Reexamination Certificate
active
06534598
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an ambient oxidative cure composition containing an acrylate functionalized alkyd resin. The invention also relates to methods of preparing an ambient oxidative cure composition containing an acrylate functionalized alkyd resin. Such compositions are useful in preparing fast-dry, high solids coatings such as, for example, enamels.
2. Description of Related Art
In recent years, considerable effort has been expended by the coatings industry to develop low or zero VOC containing coating formulations. Regulations to limit the amount of VOC content of industrial coatings have encouraged research and development to explore new technologies directed at reducing solvent emissions from industrial solvent-based coatings operations such as automotive, appliance, general metal, furniture, and the like. However, while the move to reduced organic solvent-based compositions brings health and safety benefits, these lower VOC coating compositions must still meet or exceed the performance standards expected from solvent-based compositions.
Alkyd resins are one of the most common binders used for ambient-cure, solvent-based coatings. Resistance properties of traditional solvent-borne alkyd resins are developed via autooxidative crosslinking of the alkyd film. Crosslinking occurs when the activated methylene groups in the unsaturated fatty acids or oils of the alkyd are oxidized in air to give hydroperoxides which subsequently decompose to generate free radicals for various crosslinking mechanisms. This oxidative crosslinking process is commonly accelerated by adding driers such as, for example, various salts of cobalt, zirconium, calcium, and manganese. However, while alkyd resins have shown, and continue to show promise, they have relatively slow “dry” and/or cure times, particularly at ambient temperatures. Various modifications have been made to alkyd resins in an attempt to address such concerns.
One such attempt includes polymerization of an alkyd resin with a vinyl compound, such as styrene or methyl methacrylate, via a free-radical reaction to produce a vinyl-alkyd copolymer or a vinyl alkyd. Vinyl alkyd resins generally have a higher molecular weight and a higher T
g
and accordingly produce coatings with reduced tack-free time (solvent evaporation). However, the through-dry time (oxidation of the film) of such coatings takes longer due to the decreased degree of unsaturation in the alkyd as a result of copolymerization with the vinyl compound. In addition, paint formulations which contain vinyl alkyd resins require a greater amount of solvent due to increased molecular weight and T
g
of the vinyl alkyd.
JP 48085628 describes a modified alkyd resin using glycidyl acrylate, glycidyl methacrylate, or its derivative. Drying oil-modified alkyd resins having —CO
2
H groups and an oil length of 20-80 are treated with glycidyl acrylate, glycidyl methacrylate, or its derivative in the presence of a polymerization inhibitor. The resulting resin is mixed with a photosensitizer or photoinitiator to give a coating composition which hardens with UV irradiation. However, these resin compositions were not suitable for ambient oxidative cure, high-solids coating applications.
Thus there still exists a need in the art for a modified or functionalized alkyd resin capable of undergoing crosslinking upon film formation which can be used to prepare ambient oxidative cure, fast-dry and high solids coatings having low VOC. Such coatings would exhibit the properties and advantages of high VOC coatings.
SUMMARY OF THE INVENTION
The present invention answers this need by providing an ambient oxidative cure composition comprising an acrylate functionalized alkyd resin, at least one drier, and an organic solvent. An acrylate functionalized alkyd resin is an alkyd resin modified with glycidyl acrylate via a non-free radical reaction where the glycidyl moiety of the glycidyl acrylate is the reaction moiety such that the resulting alkyd resin contains terminal reactive acrylate groups or moieties. Such an acrylate functionalized alkyd resin exhibits superior through-dry time properties. Furthermore, an acrylate functionalized alkyd resin of the invention exhibits superior tack-free time properties which previously could only be improved by increasing the molecular weight and T
g
of the alkyd resin. Since the amount of VOC generally added to alkyd resin compositions and/or formulations is directly related to the molecular weight and T
g
of the alkyd resin, compositions or formulations containing an acrylate functionalized alkyd resin of the invention would require less VOC.
The invention also relates a method of preparing an ambient oxidative cure composition comprising the step of contacting an acrylate functionalized alkyd resin with at least one drier in the presence of an organic solvent.
DETAILED DESCRIPTION OF THE INVENTION
The invention provides an ambient oxidative cure composition comprising an acrylate functionalized alkyd resin, at least one drier, and an organic solvent. In a preferred embodiment of the invention, an ambient oxidative cure composition contains about 50 to about 85 wt % based on the total weight of the composition of an acrylate functionalized alkyd resin, about 10 to about 50 wt % based on the total weight of the composition of an organic solvent, and about 0.01-1.0 wt % based on the total weight of the composition of at least one drier. According to the invention, an ambient oxidative cure composition exhibits improved tack-free and through-dry times, and may be used in enamel compositions having reduced VOC and fast through-dry and tack-free times.
An acrylate functionalized alkyd resin is an alkyd resin containing terminal reactive acrylate groups or moieties. An acrylate functionalized alkyd resin is the reaction product of a hydroxyl functional alkyd resin, an acid anhydride, and a glycidyl acrylate of which the glycidyl moiety is the reactive moiety. In a preferred embodiment of the invention, the acrylate functionalized alkyd resin comprises the reaction product of: (i) about 79 to about 95 wt % of a hydroxyl functional alkyd resin; (ii) about 2 to about 8 wt % of an acid anhydride; and (iii) about 3 to about 13 wt % of a glycidyl acrylate, each as described herein, wherein the weight percents are based on the total weight of (i), (ii) and (iii).
A hydroxyl functional alkyd resin may be any alkyd resin containing hydroxyl functionality known in the art. The hydroxyl functional alkyd may be prepared by reacting a diol, a polyol, a diacid, a monofunctional acid, and a fatty acid, fatty ester, or naturally occurring-partially saponified oil, optionally, in the presence of a catalyst. Preferably, a hydroxyl functional alkyd resin is the reaction product of(a) 0 to about 30 mole % of a diol, (b) about 10 to about 40 mole % of a polyol, (c) about 20 to about 40 mole % of a diacid, (d) 0 to about 10 mole % of a monofunctional acid, (e) about 10 to about 40 mole % of a fatty acid, fatty ester, or naturally occurring oil, and, optionally, (f) a catalyst, wherein the mole percents are based on the total moles of(a), (b), (c), (d), (e) and (f) if present. Suitable examples of each of the components of the hydroxyl functional alkyd resin include those known in the art including, but not limited to, those discussed below.
Resins for Surface Coatings
, Vol. 1, p. 127, ed. by P. K. T. Oldring and G. Hayward, SITA Technology, London, UK.
The fatty acid, fatty ester, or naturally occurring-partially saponified oil may be any fatty acid, fatty ester, or naturally occurring-partially saponified oil known in the art used in the formation of an alkyd resin. In a preferred embodiment, at least one monobasic fatty acid, fatty ester, or naturally occurring-partially saponified oil is used and selected from the following formulae (I), (II), and (III):
In formulae (I); (II), and (III), R is a saturated or unsaturated C
8
-C
20
alkyl group. More preferably, R is one of the following unsaturated C
17
alkyl groups:
In another
Clark Mark D.
Kuo Thauming
Asinovsky Olga
Eastman Chemical Company
Morgan & Lewis & Bockius, LLP
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