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
2001-07-18
2003-06-10
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...
C524S839000, C524S840000
Reexamination Certificate
active
06576702
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to waterborne polyurethane dispersions prepared using at least one plasticizer as a prepolymer diluent and in the substantial absence of other organic diluents or solvents. Such dispersions have higher solids and produce articles having lower modulus than articles made from dispersions prepared using a prepolymer diluent such as N-methyl-2-pyrrolidone (NMP).
BACKGROUND OF THE INVENTION
U.S. Pat. No. 6,017,997 (incorporated herein by reference) relates to waterborne polyurethanes having film properties comparable to rubber. A prepolymer is formed by reacting (1) a polyisocyanate compound; (2) an active hydrogen containing compound, such as a polyol or a polyamide; and (3) a water-dispersion enhancing compound having water-dispersion enhancing groups to form an isocyanate terminated prepolymer. The prepolymer is (1) neutralized by reaction with a tertiary amine, (2) dispersed in water, and (3) then chain extended by reaction with a primary or secondary amine. N-methyl-2-pyrrolidone (NMP) may be used as a coalescing (film forming) agent, and also as a diluent to render the viscosity of the prepolymer low enough to process it readily. However, NMP reduces the solids of the dispersion and is undesirable as a volatile organic compound (VOC) from an environmental standpoint. Excess isocyanate may also be used as a diluent but will increase the modulus of polyurethane articles made from the dispersions. Such higher modulus is undesirable for producing a “rubbery” polymer. There is no teaching of plasticizers as diluents or for any other purpose.
U.S. Pat. No. 4,306,998 relates to auxiliary agents and additives that are insoluble and not dispersible in water and are incorporated in oligo- and polyurethanes before the latter are dispersed in water. Plasticizers are among many such additives listed, but there is no suggestion that plasticizers replace diluents such as NMP. The desirability of solvent-free dispersions is mentioned, but solvents (acetone and NMP are among the compounds listed as solvents) generally are distilled off before the oligo- or polyurethane is dispersed or during or immediately after dispersion in order to obtain a solvent-free dispersion.
U.S. Pat. No. 4,316,832 relates to a plasticizer composition for synthetic resins consisting essentially of (a) the phthalate ester of an aliphatic alcohol containing from 5 to 12 carbon atoms in the aliphatic moiety, and intimately mixed therewith, (b) a polyurethane resin which is the reaction product of a di-isocyanate and a polyester based in part upon terephthalic acid. U.S. Pat. No. 4,242,468 relates to monohydroxylated polybutadienes as reactive or internal plasticizers for polyurethanes. U.S. Pat. No. 5,688,892 relates to an isocyanate-terminated prepolymer comprising the product of reaction between tolylene diisocyanate and a polyoxyethylenepropylene polyol, which is cured together with an aromatic polyamine crosslinker composed of diethyltoluenediamine and a plasticizer. There is no teaching in these three patents regarding waterborne polyurethane dispersions, nor any teaching of avoidance of traditional solvents such as NMP in the preparation of such waterborne polyurethanes.
U.S. Pat. No. 5,102,938 relates to compositions comprising a water-immiscible organic solvent or solvent blend, and a water-soluble polyurethane prepolymer having terminal isocyanate groups. Listed water-immiscible solvents include various ketones and plasticizers. The prepolymer is reactive in the presence of water to form a crosslinked, water-insoluble, water-containing gelatinous mass having a high degree of elasticity. There is no teaching of avoidance of traditional solvents such as NMP during preparation of waterborne polyurethane dispersions.
An improved polyurethane manufacturing process is desired that produces less hazardous waterborne polyurethane dispersions having higher solids, lower modulus, and other improved properties compared to polyurethanes of the prior art.
SUMMARY OF THE INVENTION
Waterborne polyurethane dispersions are prepared using a plasticizer as a prepolymer diluent in order to substantially or completely replace prior art diluents such as N-2-methyl pyrrolidone (NMP). Such dispersions are less hazardous, have higher solids and produce articles having lower modulus and other improved properties compared to articles made from dispersions prepared using the prior art prepolymer diluents.
The waterborne polyurethane dispersions are prepared by reacting (1) at least one polyisocyanate; (2) at least one active hydrogen containing compound, and (3) optionally, at least one water-dispersability enhancing compound having water-dispersability enhancing groups to form an isocyanate terminated prepolymer. The prepolymer subsequently is (1) optionally neutralized by reaction with at least one neutralizing agent, (2) dispersed in water, and then (3) chain extended by reaction with at least one of water, inorganic or organic polyamine having an average of about 2 or more primary and/or secondary amine groups, or combinations thereof. At least one plasticizer is introduced into the reaction mixture at any time during prepolymer formation or before the prepolymer is dispersed in water. The process is conducted in the substantial or complete absence of an organic solvent or a diluent other than the plasticizer.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to waterborne polyurethane dispersions prepared by reacting (1) at least one polyisocyanate; (2) at least one active hydrogen containing compound, such as a polyol, a polyamide, or mixture thereof; and (3) optionally, at least one water-dispersability enhancing compound having water-dispersability enhancing groups, in order to form an isocyanate terminated prepolymer. The prepolymer subsequently is (1) optionally neutralized by reaction with at least one neutralizing agent, (2) dispersed in water, and (3) then chain extended by reaction with at least one of water, inorganic or organic polyamine having an average of about 2 or more primary and/or secondary amine groups, or combinations thereof. At least one plasticizer is introduced into the reaction mixture at any time during prepolymer formation or before the prepolymer is dispersed in water. The process is conducted in the substantial absence and preferably in the complete absence of an organic solvent or a diluent other than the plasticizer.
The chain-extended prepolymer compositions of the present invention are conveniently referred to as polyurethanes because they contain urethane groups. They can be more accurately described as poly(urethane/urea)s if the active hydrogen containing compound is a polyol, or as polyureas if the active hydrogen containing compound is a polyamide. It is well understood by those skilled in the art that “polyurethanes” is a generic term used to describe polymers obtained by reacting isocyanates with at least one hydroxyl-containing compound, amine containing-compound, or mixture thereof. It also is well understood by those skilled in the art that polyurethanes also include allophanate, biuret, carbodiimide, oxazolidinyl, isocynaurate, uretdione, and other linkages in addition to urethane and urea linkages.
As used herein, the term “wt. %” means the number of parts by weight of monomer per 100 parts by weight of polymer, or the number of parts by weight of ingredient per 100 parts by weight of glove, personal care, or other composition.
Polyisocyanates
Suitable polyisocyanates have an average of about two or more isocyanate groups, preferably an average of about two to about four isocyanate groups and include aliphatic, cycloaliphatic, araliphatic, and aromatic polyisocyanates, used alone or in mixtures of two or more. Diisocyanates are more preferred.
Specific examples of suitable aliphatic polyisocyanates include alpha, omega-alkylene diisocyanates having from 5 to 20 carbon atoms, such as hexamethylene-1,6-diisocyanate, 1,12-dodecane diisocyanate, 2,2,4-trimethyl-hexamethylene diisocyanate, 2,4,4-trimethyl-hexamethylene diisocyan
Anderle Gary A.
Lenhard Susan L.
Lubnin Alexander V.
Snow George E.
Tamareselvy Krishnan
Crehore Charles A.
Dunlap Thoburn T.
Hudak, Shunk & Farine Co. LPA
Niland Patrick D.
Noveon IP Holdings Corp.
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