Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Reexamination Certificate
2000-07-27
2003-11-18
Sergent, Rabon (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C424S059000, C424S061000, C424S063000, C424S064000, C424S069000, C424S070100, C424S070700, C424S070110, C424S405000, C424SDIG001, C428S423100, C428S319700, C428S3550EN, C428S423700, C428S424200, C428S424600, C428S424800, C428S425100, C428S425500, C428S425800, C428S425900, C524S591000, C524S839000, C524S840000, C528S059000, C528S076000, C528S080000, C528S083000
Reexamination Certificate
active
06649727
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to stable aqueous colloidal dispersions of sulfonated polyurethane ureas and self-supporting films formed from these dispersions. After formation of the sulfonated polyurethane urea, alcohols can be added to the aqueous dispersion to provide a water-alcohol system. The films of the present invention are minimally tacky and self-adhesive.
BACKGROUND OF THE INVENTION
Polyurethanes are a well-established class of high performance polymers, which can be readily tailored to display unique combinations of tensile strength, toughness, and flexibility. As a result of this versatility, polyurethanes have found utility in a variety of applications including binder resins, abrasion resistant coatings, protective coatings, and membranes.
Polyurethanes may be delivered to a substrate in one of three ways: i) extruded as a melt processable thermoplastic or thermoset material, ii) delivered as a moisture curable or two part curable system, generally from an organic solvent, or iii) delivered as an aqueous dispersion of a colloidal polymer system. Two part polyurethanes are generally used in binder or coating applications where they are delivered either from mixtures of organic solvents, blocked isocyanate terminated compounds, and diamine curatives, or mixtures of organic solvents, a diisocyanate terminated compound and polyols.
Aqueous polyurethane dispersions are utilized when high performance polyurethane properties are required but where volatile organic chemicals are not desirable. They offer advantages in that they have reduced volatile organic compound (VOC) emissions; they may eliminate exposure to toxic isocyanate or diamine compounds during coating; and they provide simplified overall processing. Aqueous polyurethane dispersions have been developed commercially as a means to deliver polyurethane coatings to a wide variety of substrates, including, for example, fibers, textiles, paper, films, wood, and concrete.
WO 99/05192 discloses aqueous colloidal dispersions of sulfopolyureas, comprising a high content of hard segments derived from aromatic diisocyanates, and films formed from these dispersions. The films have improved thermal stability and thus, improved high temperature performance, and may be used to form heat resistant abrasive articles. They are not redispersible in water.
U.S. Pat. No. 4,307,219 describes linear polyurethane resins that are prepared in an inert organic solvent under essentially anhydrous conditions and that once coated and dried, can be redispersed in water and aqueous organic solvents.
U.S. Pat. No. 4,738,992 describes a water-absorbing sponge comprising at least one of a pendant sulfo-group containing polyurea and polyurethane. The sponge comprises the reaction product of an isocyanate-terminated sulfopolyurethane/urea, a polyisocyanate, an isocyanate-terminated polyurethane/urea, and a compound selected from the group consisting of water and a polyol or polyamine plus a blowing agent.
None of the technologies discussed above provide a polyurethane dispersion capable of forming self-supporting films that are minimally tacky and self-adhesive, nor do they suggest the use of these materials in cosmetic formulations.
Therefore, a need exists in the art for a polyurethane dispersion stable in water and water-alcohol solvent systems, where the dispersion has one or more of the following properties: minimal tack and high self-adhesion, capable of forming stable dispersions in water and water-alcohol systems, and capable of rapidly forming films on skin or hair by simple ambient evaporation.
SUMMARY OF THE INVENTION
The present invention relates to stable aqueous colloidal dispersions of sulfonated polyurethane ureas and films formed from these dispersions.
In brief summary, sulfonated polyurethane ureas of the present invention comprise the reaction product of:
(a) one or more sulfonated polyols;
(b) one or more non-sulfonated polyols;
(c) one or more aliphatic polyisocyanates, having 2 to 25 carbon atoms, or cycloaliphatic polyisocyanates, having 3 to 25 carbon atoms; and
(d) excess water,
wherein the reaction product of (a), (b), and (c) with (d) comprises a polyurea segment of the following formula:
wherein z is an integer from 0 to 6 and R
3
is an aliphatic group, having 2 to 25 carbon atoms, or a cycloaliphatic group, having 3 to 25 carbon atoms, derived from the aliphatic or cycloaliphatic polyisocyanate. The reaction of (a), (b), and (c) forms an isocyanate terminated prepolymer mixture that has an isocyanate to hydroxyl ratio of 1.3 to 2.5:1. Excess water means that the water is in an amount greater than the amount of isocyanate terminated prepolymer mixture (w/w) such that a final aqueous dispersion of less than 50% solids is achieved. The reaction product of (a), (b) and (c) with (d) provides a sulfonated polyurethane urea that has a sulfonate equivalent weight of from about 1000 to about 8500 and that has been chain-extended only with water.
Another aspect of the present invention relates to stable aqueous dispersions prepared from the sulfonated polyurethane ureas described above.
An additional aspect of the present invention relates to self-supporting films prepared from the sulfonated polyurethane ureas described above. These films are formed with no volatile organic compound emissions and with no post-coating chemical or ionic cross-linking; therefore, the overall processing to form the films is simplified into one step. The films of the present invention are minimally tacky and self-adhesive. Some films of the present invention can also be redispersible in water.
GLOSSARY
In this application:
“Aliphatic” means a non-aromatic group, which can be a straight or branched chain alkylene group of 2 to 25 carbon atoms wherein these groups may be optionally substituted, for example, with ether, ester, or cycloaliphatic functional groups.
“Colloidal dispersion” means a discrete distribution of particles having an average size of less than about 1 micron, typically less than about 500 nanometers, in an aqueous media (water) or in a water-alcohol media.
“Cohesive” means having auto-adhesion or self-adhesion, i.e., the capability of adhering to itself.
“Cycloaliphatic” means a non-aromatic, optionally substituted cyclic group of 3 to 25 carbons, wherein one to three carbon atoms may be optionally replaced with a heteroatom, for example, nitrogen or oxygen, or C(O). The cycloaliphatic group may be optionally substituted, for example, with alkyl, ether, or ester functional groups.
“Minimally tacky” means having a relatively low degree of tack, preferably non-tacky. Therefore, minimally tacky includes compositions that are tack free; very, very, low tack; very low tack, and low tack when tested by a “finger appeal” test. The finger appeal test involves qualitatively assessing an adhesive by a light touch and short contact time at room temperature (about 20° to 30° C.) and assigning a value of 1 through 5, where 1=tack free, 1.25=very, very, low tack, 1.5=very low tack, 2=low tack, 2.5=low-to-medium tack, 3=medium tack, 3.5=medium-to-good tack, 4=good tack, and 5=excellent tack. On this scale, Scotch™ Magic™ transparent tape from Minnesota Mining and Manufacturing Co. (3M), St. Paul, Minn., USA has a rating of 5.
“Polyurea” means a polymer obtained by a polymerization reaction in which the mechanism of chain growth is entirely the formation of urea and biuret linkages by the reaction of isocyanate groups with amine or urea groups, with urea linkage formation predominating.
“Self-adhesion” means a material preferentially adheres to itself or a chemically similar material under pressure or force without the need for significantly elevated temperatures (e.g., without the need for temperatures above about 50° C.). Preferred compositions of the invention exhibit self-adhesion properties immediately upon contact to itself at room temperature (about 20° to 30° C.). As used in the previous sentence, the term “immediately” means less than a few minute
Anderson Jeffrey T.
Creel Howard S.
Hedrick Steven T.
Kantner Steven S.
Spawn Carol-Lynn
3M Innovative Properties Company
Lambert Nancy M.
Sergent Rabon
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