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
2000-03-30
2001-11-13
Niland, Patrick D. (Department: 1714)
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...
C524S589000, C524S839000, C524S840000, C524S591000, C528S044000, C528S059000, C528S060000, C528S061000, C528S065000, C528S066000, C528S076000, C528S077000, C528S085000
Reexamination Certificate
active
06316540
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to hydrophilically end-capped polyurethane thickeners having particular utility in paints, coatings and other aqueous systems.
Thickeners have been known for use in paints and coatings for many years. They can be naturally occurring or synthetically manufactured. Examples of naturally occurring thickeners include alginates, casein, gum karaya, locust bean gum, cellulosics such as methyl cellulose, hydroxyethyl cellulose and hydroxypropylmethyl cellulose.
Examples of synthetic thickeners include the compositions of U.S. Pat. Nos. 4,079,028 (Emmons et al.), 4,180,491 (Kim et al.), 4,327,008 (Schimmel et al.), 4,373,083 (Seiner et al.), 4,426,485 (Hoy et al.), 4,436,862 (Tetenbaum et al.), 4,496,708 (Dehm et al.) and 4,514,552 (Shay et al.).
U.S. Pat. No. 4,079,028 purports to teach latex systems containing a low molecular weight polyurethane thickener characterized by at least three hydrophobic groups interconnected by hydrophilic polyether groups.
U.S. Pat. No. 4,180,491 purports to teach nonionic polyurethane thickeners for print pastes, which thickeners are characterized by a molecular weight of at least 10,000 and having at least three hydrophobic branching groups linked through hydrophilic polyether segments.
U.S. Pat. No. 4,327,008 purports to teach rheology modifiers useful in water-based and organic solvent-based compositions, which modifiers are derived from the reaction of polyalkylene oxide, polyfunctional material (such as polyol, amine, amine alcohol, thiol or polyisocyanate), diisocyanate, water and a monofunctional active hydrogen-containing compound or monoisocyanate.
U.S. Pat. No. 4,373,083 purports to teach a process for making rheology modifiers (particularly those of U.S. Pat. No. 4,079,028) useful in water and organic solvent-based compositions, which modifiers are derived from the reaction of polyalkylene oxide, polyfunctional material (such as polyol, amine, amine alcohol, thiol or polyisocyanate), diisocyanate, water and end-capping compounds in an organic solvent.
U.S. Pat. No. 4,426,485 purports to teach water soluble, thickeners for aqueous systems which are characterized by deliberate, arranged bunches of hydrophobes bonded to a water-soluble backbone.
U.S. Pat. No. 4,436,862 purports to teach thickeners composed of a clay stabilizer and a water-dispersable polyurethane.
U.S. Pat. No. 4,496,708 purports to teach water-soluble comb polyurethane thickeners having hydrophilic polyether backbones and pendant monovalent hydrophobic groups.
U.S. Pat. No. 4,514,552 purports to teach alkali soluble thickeners which are aqueous emulsion copolymers of a,b-monoethylenically unsaturated carboxylic acid, monoethylenically unsaturated monomer (such as ethyl acrylate), nonionic urethane monomer which is the reaction product of a monohydric surfactant and a monoisocyanate, and optionally a polyethylenically unsaturated monomer.
In contrast to the above, the present invention relates to hydrophilically end-capped polyurethane thickener compositions which are particularly suited for use in paint and coating compositions. Whereas the patents discussed above all teach the use of hydrophobic end-capping groups to attain thickening efficiency, the present invention utilizes hydrophilic end groups.
SUMMARY OF THE INVENTION
As stated above, the present invention relates to hydrophilically end-capped polyurethane thickener compositions. In particular, the compositions of this invention are the reaction product of:
(1) the reaction product of an isocyanate starting material, preferably a diisocyanate,
(2) a polyether polyol, preferably a polyalkylene oxide such as polyethylene glycol having a molecular weight between about 1000 and about 20,000, and (b) a linear difunctional hydrophilic endcapping material other than a polyether polyol that is reactive with isocyanate groups, preferably a C4-C20 linear diol having hydroxy groups which are positioned at or near the ends of the diol chain.
The compositions of this invention can be linear structures. The compositions of this invention are excellent thickeners and rheology modifying agents. These compositions are characterized by hydrophilic end caps which provide a definite and desirable impact on the compositions rheology modifying properties.
DETAILED DESCRIPTION OF THE INVENTION
As stated above, the compositions of this invention are hydrophilically-modified polyurethane thickeners which are the reaction product of:
(a) (1) the reaction product of an isocyanate starting material, preferably a diisocyanate,
(2) a polyether polyol, preferably a polyalkylene oxide such as polyethylene glycol having a molecular weight between about 1000 and about 20,000, and (b) a linear difunctional hydrophilic endcapping material other than a polyether polyol that is reactive with isocyanate groups, preferably C4-C20 linear diol having hydroxy groups which are positioned at or near the ends of the diol chain.
The first starting material, an isocyanate-starting material, can be aliphatic, cycloaliphatic or aromatic, and may be used singly or in combination with other isocyanate-functional materials. The isocyanate-starting material should have at least two or more reactive isocyanate groups. Exemplary diisocyanates include the aliphatic, cycloaliphatic and aromatic diisocyanates either alone or in admixture. Generally, such diisocyanates have the formula OCN—R—NCO where R is arylene (e.g. phenylene and diphenylene), alkylarylene (e.g. dimethylbiphenylene, methylenebisphenyl and dimethylmethylenebisphenylene), alkylene (e.g. methylene, ethylene, tetramethylene, hexamethylene, a 36 methylene species, and trimethylhexylene), and acyclic (e.g. isophorone and methylcyclohexylene. Or, R can be a hydrocarbon group containing ester or ether linkages. Specific examples of such diisocyanates include 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-trimethyl-1,6-diisocyanato hexane, 1,10-decamethylene diisocyanate, 1,4-cyclohexylene diisocyanate, 4,4′-methylene bis(isocyanato cyclehexane), p-phenylene diisocyanate, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, xylene diisocyanate, isophorone diisocyanate, bis para-isocyanato cyclohexylmethane, 4,4-biphenylene diisocyanate, 4,4-methylene diphenyl isocyanate, 1,5-naphthalene diisocyanate, benzene 1,3-bis (1-isocyanato-1-methylethyl) and 1,5-tetrahydronaphthalene diisocyanate. If producing a branched composition, suitable triisocyanates include aromatic triisocyanate adduct of trimethylol propane and tolylene diisocyanate sold under the brand name Mondur CB-75, and aliphatic triisocyanate product of the hydrolytic trimerization of 1,6-hexamethylene diisocyanate, sold under the brand name Desmodur N.
Most preferred are dicyclohexylmethane-4,4′-diisocyanate sold under the brand name Desmodur W, isophorone diisocyanate, diphenylmethane-4,4′-diisocyanate sold under the brand name Mondur XP744 and isocyanurate trimer of hexamethylene diisocyanate sold under the brand name Desmodur N-3300.
The isocyanate-starting material should be used in an amount of between about 30.0% to about 50.0% (molar percent of all reactants), preferably between about 35.0% to about 45.0%.
The second starting material, the polyether polyol, is preferably a polyalkylene oxide such as polyethylene glycol having a molecular weight between about 1000 and about 20,000. Suitable materials include the adducts of an aliphatic, cycloaliphatic or aromatic polyhydroxy compound such as a polyhydric alcohol or polyhydric alcohol ether and an alkylene oxide such as ethylene oxide or propylene oxide. Or, they may be hydroxyl-terminated prepolymers of such adducts and an organic polyisocyanate. Mixtures of two or more such materials are also acceptable. Polyhydric alcohols include not only the simple glycols such as ethylene glycol, polyethylene glycol, propylene glycol and polypropylene glycol, but also hydroxy compounds having three or more hydroxyl groups such as polyalkylolalkanes (e.g. trimethylolpropane, pentaerythritol) and polyhydroxyalkanes (e.g. gly
Kayima Paul M.
Krafcik Randolph B.
Sharrotta Anthony B.
Tomko Revathi
Youn Hyeong-Chan
McDonald Robert E.
Niland Patrick D.
The Sherwin-Williams Company
Tsang Vivien Y.
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