Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2000-05-08
2002-01-29
Trinh, Ba K. (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C549S557000, C525S327300, C526S273000
Reexamination Certificate
active
06342615
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to glycidyl esters whose adducts with acrylic or methacrylic acid exhibit increased effective glass transition temperatures and their use as reactants in preparing polymer compositions.
1. Description of Related Art
Glycidyl esters of monocarboxylic acids are well known materials which are useful as chemical intermediates in the preparation of acrylic, polyester, and alkyd resins, or as reactive diluents in the preparation of thermoset epoxy, polyester and urethane paints and coatings.
Of particular interest are glycidyl esters of aliphatic monocarboxylic acids represented by the empirical formula
wherein R
1
, R
2
and R
3
each represent the same or different alkyl radicals of normal or branched structure containing 1-20 carbon atoms, and R
4
through R
8
each represent hydrogen or a hydrocarbyl group containing 1-3 carbon atoms. A more preferred product is one where R
1
through R
3
are alkyl radicals containing a sum total of 3-20 carbon atoms and where R
4
through R
8
are each hydrogen, e.g., the reaction product of neodecanoic acid (R
1
+R
2
+R
3
=C
8
) and epichlorohydrin.
Glycidyl esters of this general type and their method of preparation are disclosed in U.S. Pat. No. 3075999, U.S. Pat. No. 3178454, U.S. Pat. No. 3275583 and U.S. Pat. No. 3397176, the complete disclosures of each of which are incorporated herein by reference.
Such glycidyl esters can be made by reacting an alkali salt of the carboxylic acid with a halo-substituted monoepoxide such as an epihalohydrin, e.g., epichlorohydrin (1-20 molar excess). The mixture is heated (50°-150° C.) in the presence of a catalyst forming glycidyl ester plus alkali salt and water. The water and excess epihalohydrin are removed by azeotropic distillation, and the salt by-product, e.g., NaCl, is removed by filtration and/or washing. The glycidyl esters can also be made by reacting the carboxylic acid directly with epichlorohydrin under similar process conditions. The chlorohydrin ester intermediate formed during this reaction is subsequently treated with an alkaline material, e.g., sodium or potassium hydroxide, which yields the desired glycidyl ester. By-product salt is removed by washing and/or filtration, and water is removed by drying.
Investigations of these reactions reveal that several heavier by-products are produced during the reactions to varying degrees, and species which add color to the main product are contained within the heavier by-products. The heavier by-products include the reaction products of the glycidyl ester product and/or the chlorohydrin ester intermediate with either unreacted epichlorohydrin, unreacted monocarboxylic acid or salt and/or water at various stages of the synthesis process in accordance with the following overall reaction schemes:
The heavier by-products may also include further reaction products of compounds A, B and/or C with the glycidyl ester product and other species present. Generally speaking, one or a combination of these or other unidentified heavies are present in the glycidyl ester reaction product at levels in excess of about 3 wt %, e.g., about 4-12 wt %.
Because glycidyl esters are thermally and chemically reactive molecules, separation of these by-products from glycidyl esters is not easily accomplished. Standard atmospheric distillation techniques have been found to increase the amount of by-products as well as the degree of color of the esters. It is believed that this increase in color is caused by the reaction at elevated temperatures, as encountered during distillation, of the glycidyl functionality present in the desired product with functionalities present in the by-products, thereby forming additional by-products. Surprisingly, standard vacuum distillation has also been found to be ineffective in reducing the initial or aged color of the glycidyl esters, and tends to worsen the color problem.
Japanese Patent 46 (1971) 37326 discloses a process for manufacturing an unsaturated organic acid glycidyl ester by reacting a salt of the unsaturated acid (acrylic or methacrylic acid) with a molar excess of epichlorohydrin. The residual unreacted epichlorohydrin is then distilled out of the reaction product using thin film distillation techniques. The resulting product is further distilled using thin film evaporation techniques to provide a purer product having improved color stability after periods of storage. The reference teaches that the process avoids the polymerization of the acrylic monomers observed during conventional distillation and thereby eliminates the need to include a polymerization inhibitor in the reaction product which inhibitor retards polymerization of the unsaturated monomers but which also reacts with the epoxy compounds to give products of less purity.
Copending U.S. application Ser. No. 08/861,408, filed May 21, 1997, discloses a process for the distillation of the glycidyl ester reaction product composition of one or more straight or branched chain saturated monocarboxylic acids or salts thereof and a halo-substituted monoepoxide comprising subjecting said reaction product composition to conditions of temperature and vacuum in a thin film, short pass distillation apparatus, and recovering a light fraction having a Pt—Co color value of less than about 100 after 20 days storage in contact with air at about 125° C., as measured in Pt—Co units in accordance with ASTM D1209.
Products produced according to that invention are of significantly reduced initial color and exhibit improved color stability after periods of storage, thereby minimizing any color contribution by these products in systems where they are used, e.g., in the preparation of alkyd, polyester or acrylic resins and especially in coating and paint formulations containing these products.
Various researchers have been pursuing new polymer compositions which will give a better balance of properties when these polymeric binders are formulated into paints. Of particular importance is maintaining good film properties (hardness, flexibility, durability, etc.) as polymer molecular weights and viscosity are reduced. The latter is essential to reduce the amount of solvent, i.e., volatile organic compounds (VOCs), in the paints. These VOCs are being regulated to reduce air pollution.
One important factor which influences paint and film properties is the glass transition temperature (Tg) of the polymer(s) and/or oligomer(s) used as paint binders. Usually a specific value or range of Tg is required to meet the performance requirements of a given application. Another important factor which influences paint and film properties is the nature of the functional group incorporated in the polymer. In many cases this is a hydroxyl group. One of the better hydroxyl groups used in acrylic polymers, for example, comes from an adduct of glycidyl neodecanoate and either methacrylic acid or acrylic acid. These adducts can impart improved paint and film properties over similar acrylic polymers (same OH concentration, Tg, and molecular weight) made with other hydroxy functional monomers. Improved weatherability and chemical resistances and lower viscosity (i.e., lower VOC) are notable features attributable to these adducts.
It is a significant challenge, however, to obtain useful lower molecular weight acrylic polymers with hydroxy (OH) functionalities based solely on these adducts. In particular, as molecular weights decrease, one must increase the relative proportion of hydroxy functional monomers to maintain good film properties. With glycidyl neodecanoate adducts which have relatively low effective Tgs, this can lower the maximum polymer Tg below desired levels. Consequently, to get the best possible film properties one would like to have a monomer which provides the durability and chemical resistance of the glycidyl neodecanoate adducts, but with a higher Tg.
We have discovered that by using purified glycidyl esters of neo acids particularly those derived from isobutylene and/or isobutylene oligomers, one can obtain glycidyl ester adducts
Keenan Michael J.
Kowalik Ralph Martin
McGlamery, Jr. Gerald G.
Ryan Richard William
Collins Douglas J.
ExxonMobil Chemicals Patents Inc.
Trinh Ba K.
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