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
2001-06-04
2003-02-11
Wu, David W. (Department: 1713)
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...
C524S502000, C524S544000
Reexamination Certificate
active
06518351
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to aqueous dispersions of urethane-acrylic copolymers containing fluorinated acrylic monomers and to their use as finishing agents of textiles, leather and paper. The present invention particularly relates to the use of the dispersions in oil-repellent and water-repellent treatments.
2. Description of the Prior Art
Aqueous emulsions containing fluorocarbonic resins are widely used as finishing agents in the textile, leather and paper fields, because they impart good characteristics of oil- and water repellency to the substrates treated therewith. Many examples of aqueous emulsions containing fluorocarbonic resins, useful for the treatment of textiles, paper and leather, are described in the prior art literature.
By way of example, U.S. Pat. No. 5,164,252 (US1) describes hydrophobizing and oleophobizing compositions containing physical mixtures of a polymer containing perfluoroalkyl groups and of a cationically modified polyurethane dispersion, but it does not teach how to obtain a copolymer from the mixtures.
U.S. Pat. No. 5,346,949 (US2) describes aqueous emulsions containing fluorinated and non-fluorinated monomers mixed with a water soluble non-urethane cationic polymer which is able to increase the fixing properties of the resin on textiles. The water soluble cationic polymers used in US2 are expensive and not readily commercially available.
In U.S. Pat. No. 5,115,013 (US3), the preparation and the use in the finishing of natural or synthetic materials of aqueous dispersions of polyurethane-acrylate containing from 5 to 30 percent of fluorine, are described. The dispersions are obtained by grafting a mixture of acrylic monomers, some of which containing fluorine, onto non-functionalized cationic polyurethane dispersions.
In EP 98752 (EP1) a process for the preparation of stable aqueous dispersions of oligourethane-acrylate vinyl terminated containing hydrophilic ionizable groups, anionic or cationic, is described.
In EP 183119 (EP2) copolymers of &agr;,&bgr;-ethylenically unsaturated monomers, modified with from 5 to 60 percent by weight, extremes included, of an oligourethane containing ionizable groups and &agr;,&bgr;unsaturated terminal groups derived from acrylic and methacrylic monomers, are described. In EP2 neither the use of fluorinated monomers nor the use of the copolymers are cited in oil- and water repellent treatment. EP2 also describes the process for the preparation of the compounds. The EP2 process is not suited for the synthesis of the cationic perfluorinated urethane-acrylate copolymers of the present invention due to the poor emulsionability of the fluorinated monomers in the reaction medium.
SUMMARY OF THE INVENTION
On one aspect, the present invention is an aqueous dispersions of cationic urethane-acrylic copolymers containing fluorinated acrylic monomers characterized in that the dispersions are obtained by radical polymerization in aqueous dispersion of fluorinated and non-fluorinated acrylic monomers and of vinyl terminated polyurethane-acrylates containing cationic groups.
In another aspect, the present invention is a process for the radical polymerization in aqueous dispersion of mixtures of fluorinated and non-fluorinated acrylic monomers (A) on vinyl terminated polyurethane-acrylates containing cationic groups (B), characterized by preparing a pre-emulsion of (A) and of an aqueous dispersion of (B) by reducing the size of their particles to a value <0.15 micron; by warming up the pre-emulsion to from 30° to 100° C. and by polymerizing by adding an initiator of radical polymerization.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
According to the present invention, a group of fluorinated copolymers has been found, which is different in structure from the copolymers known for the same use and is prepared as a stable water dispersion. The water dispersion can be used as finishing agent in oil- and water-repellent treatment and is surprisingly effective even when used at low concentrations.
It is a main object of the present invention to provide aqueous dispersions of cationic urethane-acrylic copolymers containing fluorinated acrylic monomers obtained by radical polymerization in aqueous dispersion of fluorinated and non-fluorinated acrylic monomers (A) and of vinyl terminated polyurethane-acrylates containing cationic groups in aqueous dispersion (B). It has been found that the product obtained from the reaction of A with B give excellent oil and water repellent effects to the materials treated and finished with it, effects that are surprisingly much better than the ones obtained using A and B in physical mixture.
While not wishing to be bound by any particular theory as to the explanation of the reasons why the product obtained from the reaction of A with B exhibits a better performance in comparison with their physical mixtures, it is supposed that the fact that A and B are covalently bonded permits a better fixation of the active to textiles.
According to a fundamental aspect of the present invention, the amount of fluorinated acrylic monomer, which is the most expensive component of the mixtures normally used to obtain the expected effects, has been successfully decreased, while obtaining similar or better results in comparison with the ones obtained by the use of the separate components.
It is a further object of the present invention the procedure for obtaining the dispersions by radical polymerization of mixtures of fluorinated and non-fluorinated acrylic monomers, on vinyl terminated polyurethane-acrylates containing ionizable cationic groups.
It has now been found that the use of vinyl terminated urethane-acrylic copolymers as a base for the polymerization of fluorinated acrylic monomers permits a notable reduction of the amount of the surfactants that are normally used in polymerization or in the preparation of this kind of emulsions and that reduce the oil- and water repellent effects on textiles in the application step.
The vinyl terminated polyurethane-acrylates containing cationic groups in aqueous dispersion (B) can be obtained following the procedure described in EP 98752. According to EP 98752, aqueous dispersion of the vinyl terminated polyurethane-acrylates can be prepared by reacting, in a first step, an excess of an organic diisocyanate with a mixture of a diol containing ionizable groups and of an essentially linear macroglycol of the polyol-polyester type and/or polyol-polyether type having a molecular weight from 500 to 5,000 in order to obtain a prepolymer containing free isocyanate groups. The prepolymer is then converted into the vinyl terminated polyurethane-acrylate by reaction with a compound having hydroxyl groups able to react with isocyanic groups that has the following formula:
CH
2
═C(R)—COOX
where R is a methyl group or a hydrogen atom and X is a hydroxyalkyl group. The vinyl terminated polyurethane-acrylate is successively salified.
The preparation of the vinyl terminated cationic polyurethane-acrylate and its successive salification can be done using the same molar ratios described in EP 98752. The vinyl terminated polyurethane-acrylate thus obtained has a molecular weight from 2,000 to 50,000.
The utilizable organic diisocyanate of the present invention may be either of the aromatic, or of the aliphatic or of the cycloaliphatic type. Examples of suitable diisocyanates are 4,4′-dicyclohexyl-methanediisocyanate, 1-isocyanate-3-isocyanate-methyl-3,5,5-trimethyl-cyclohexane (or isophoronediisocyanate), 2,2,4-trimethyl-hexamethylene diisocyanate in admixture with the 2,6,4-trimethyl-hexamethylene diisocyanate isomer, 2,4- toluenediisocyanate either alone or in admixture with the 2,6-toluenediisocyanate isomer, and 4,4′-diphenyl-methanediisocyanate, or mixtures thereof.
As ionizable diols, the diols bearing tertiary amine groups, such as methyidiethanolamine, are particularly suitable according to the present invention. The utilizable macroglycols according to the present invention have a molecular weight fr
Alanzo Vito
Bassi Giuseppe Li
Giordano Sergio
Locatelli Monica
Cheung William
Lamberti SPA
Wu David W.
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