Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-01-18
2001-01-09
Acquah, Samuel A. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C528S272000, C528S296000, C528S300000, C528S301000, C528S302000, C528S307000, C528S308000, C524S539000, C524S600000, C524S601000, C524S773000, C524S802000, C524S843000, C525S437000, C525S440030, C525S444000
Reexamination Certificate
active
06172159
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to water-reducible polyester resins and urethane coatings produced therefrom and, more particularly, to water-reducible polyester resins and urethane coatings which provide improved performance characteristics which render them useful for numerous interior and exterior applications which require a high gloss, good flexibility and excellent solvent resistance.
While two component urethane coatings or polyol-diisocyanate coatings are available, there is a continuing need to develop improved and less expensive water-reducible polyester resins and urethane coatings produced therefrom which exhibit the desired performance properties including low volatile organic components formulations with no hazardous air pollutants, low odor and excellent adhesion in direct to metal application.
SUMMARY OF THE INVENTION
Among the several objects of the invention may be noted the provision of novel water-reducible polyester resins for use in producing urethane coatings; the provision of such polyester resins which comprises the reaction product of an anhydride, a polyol and a polyethylene glycol and which has a functionality between approximately 2 and 2.6 and the reaction product of these same components and a nonionic surfactant; the provision of urethane coatings for various substrates comprised of the reaction product of said water-reducible polyester resins and an aliphatic diisocyanate; and the provision of such urethane coatings which exhibit improved performance properties and are generally less expensive to produce than available urethane coatings. Other objects and features will be in part apparent and in part pointed out hereinafter.
Briefly, the present invention is directed to a water-reducible polyester resin for use in producing urethane coatings which comprises the reaction product of (a) hexahydrophthalic anhydride, trimellitic anhydride or phthalic anhydride; (b) 1,4-cyclohexane dimethanol or trimethylolpropane; and (c) a polyethylene glycol, a methoxy polyethylene glycol or trifunctional polyethylene glycol having a molecular weight no greater than approximately 1050; the reaction product having a functionality between approximately 2 and 2.6. The invention is also directed to such a polyester resin which additionally contains a nonionic surfactant which is a polyoxyalkylene derivative of ethylene glycol, ethylene oxide, propylene glycol and propylene oxide having terminal hydroxy groups and a molecular weight between approximately 300 and 10,000.
The invention is further directed to a urethane coating for substrates which comprises the reaction product of a blend of the two above-noted polyester resin products and an aliphatic diisocyanate such as a trimer of hexamethylene diisocyanate.
DESCRIPTION OF PREFERRED EMBODIMENTS
In accordance with the present invention, it has now been found that improved water-reducible polyester resins for use in producing urethane coatings may be provided by formulating the reaction product of (a) an anhydride which may be hexahydrophthalic anhydride, trimellitic anhydride or phthalic anhydride; (b) a polyol which may be 1,4-cyclohexane dimethanol or trimethylol propane or mixtures thereof; and (c) a polyethylene glycol which may be a polyethylene glycol, methoxy polyethylene glycol or trifunctional polyethylene glycol having a molecular weight no greater than approximately 1050, the reaction product having a functionality between approximately 2 and 2.6, preferably 2.3. The resulting reaction product is a polymer having ester linkages and is water-soluble. The proportions of components (a), (b) and (c) may vary but are selected so as to provide the reaction product with a functionality between approximately 2 and 2.6, i.e. the functionality is the number of carboxyl and hydroxyl groups in the reaction product added together and averaged on a weight basis. In practice, it is preferred that component (a) be constituted by a mixture of hexahydrophthalic anhydride and trimellitic anhydride, but either anhydride or phthalic anhydride may also be employed. As used herein, the term “phthalic anhydride” means phthalic anhydride and related functional isomeric equivalents of phthalic acid. Similarly, it is preferred that a mixture of 1,4-cyclohexane dimethanol and trimethylol propane be used as component (b). With respect to component (c), various polyethylene glycols having a molecular weight no greater than approximately 1050 may be used in the practice of the invention. Preferred for usage are a polyethylene glycol having a molecular weight of approximately 380 to 420 (e.g. Carbowax 400, Union Carbide Corporation) or a trifunctional polyethylene glycol having a molecular weight of approximately 950 to 1050 (e.g. Carbowax 990, Union Carbide Corporation). Other Carbowax polyethylene glycols having a molecular weight no greater than 1050 may be used. It is also preferred that a polyethylene glycol such as Carbowax 400 constitute at least approximately 40% by weight of the polyester resin reaction product produced from components (a), (b) and (c).
In carrying out the invention, components (a), (b) and (c) are loaded into a reactor and heated to approximately 500-530° F., preferably 520° F. The mixture is held at this temperature until an acid value of approximately 6.0 maximum and a viscosity of, for example, Z
5
-Z
6
on the Gardner Holt scale at 100% nonvolatile material are achieved. Water of reaction is removed and the resulting polyester resin reaction product is then cooled and packed off for further use as described below.
In further accordance with the invention, a second polyester resin reaction product is formulated from components (a), (b) and (c) as described above with a fourth component constituted by a nonionic surfactant which may be a polyoxyalkylene derivative of ethylene oxide and ethylene glycol and propylene oxide and propylene glycol having terminal hydroxy groups and a molecular weight between approximately 300 and 10,000, the resulting reaction product again having a functionality between approximately 2 an 2.6, preferably 2.3. Such surfactants have the structure:
prepared by the controlled addition of propylene oxide to the two hydroxyl groups of propylene glycol to form a hydrophobe followed by the addition of ethylene oxide to sandwich the hydrophobe between hydrophilic groups. Such surfactants may also have the structure:
prepared by adding ethylene oxide to ethylene glycol to provide a hydrophile followed by the addition of propylene oxide to obtain hydrophobic blocks on the outside of the molecule. Thus, for example, the nonionic surfactant may be a polyoxyalkylene derivative of ethylene oxide, propylene oxide and propylene glycol such as Pluronic F108 (molecular weight 3000; 80% ethylene oxide), Pluronic F38 (molecular weight 900; 80% ethylene oxide), Pluronic F68 (molecular weight 1800; 80% ethylene oxide), Pluronic F98 (molecular weight 2700; 80% ethylene oxide), Pluronic F127 (molecular weight 3600; 70% ethylene oxide), or a polyoxyalkylene derivative of propylene oxide, ethylene oxide and ethylene glycol such as Pluronic 10R5 (molecular weight 1000; 50% propylene oxide or Pluronic 17R4 (molecular weight 1700; 40% propylene oxide). All Pluronic surfactants are marketed by BASF. The amount of nonionic surfactant employed is relatively small (e.g. 4.0 weight percent) and its proportion together with the proportions of components (a), (b) and (c) are such that the reaction product has a functionality between approximately 2 and 2.6, preferably 2.3.
In preparing the second polyester resin product, the mixture of components (a), (b), (c) and the nonionic surfactant component is heated to approximately 500-530° F., preferably 520° F. and held at that temperature until an acid value of approximately 6.0 maximum and a viscosity of, for example, Z
6
-Z
7
on the Gardner Holt scale at 100% nonvolatile material are achieved. Water of reaction is removed and the resulting second polyester resin reaction product, a semi-solid in the nature of Vaseline, is cooled and packed off for
Gaal, Jr. Robert J.
Heitland Roger W.
Accures Corporation
Acquah Samuel A.
Senniger Powers Leavitt & Roedel
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