Aqueous dispersions of fluorinated polyurethanes and their use for textile coatings

Claim 2

Stable aqueous dispersins of fluorinated polyurethanes containing in their macromolecules hydrophilic ionic groups, both of anionic and cationic character, obtainable accord­ing to the following steps: (a) preparation of a fluorinated polyisocyanate, by reac­tion between an organic diisocyanate and a mixture com­prising diols containing ionizable groups and macrogly­cols comprising polyols and at least 1 % by weight of one or more hydroxy- and/or carboxy-capped fluoropoly­ethers; (b) salification of the so-obtained fluorinated polyiso­cyanate, to convert the ionizable groups into hydrophi­lic cations or anions; and (c) dispersion and chain extension of the salified fluorina­ted polyisocyanate in water.

Claim 3

Aqueous dispersions according to claim 1, wherein the mo­lar ratio between the isocyanate groups to the sum of the hydroxyl groups is within the range of from 1.2 to 2, and preferably is 1.5.

Claim 4

Aqueous dispersions according to claim 1 or 2, wherein the macroglycols comprise from 3 to 20 % by weight of one or more hydroxy- and/or carboxy-capped fluoropolyethers.

Claim 5

Aqueous dispersions according to any one of claims 1 to 3, wherein the hydroxy- and/or carboxy-capped fluoropoly­ethers have a molecular weight within the range of from 500 to 7000, preferably 1000 to 2500.

Claim 6

Aqueous dispersions according to any one of claims 1 to 4, wherein the hydroxy- and/or carboxy-capped fluoropoly­ethers are selected from the class consisting of those hav­ing the formulae: Y-R₁-CF₂-O-(C₂F₄O) m -(CF₂O) n -CF₂-R₁-Y      (I) Y-R₁-CF₂-O-(C₃F₆O) d -CF₂-R₁-Y      (III) Y-R₁-CF₂-(OC₂F₄CH₂) b -OR f O-(CH₂C₂F₄O) b -CF₂-R₁-Y      (IV) Y-R₁-CF₂-O-(C₂F₄O) r -CF₂-R₁-Y      (V) Y-R₁-CF₂-(OCF₂CF₂CH₂) g -O-CF₂-R₁-Y      (IX) wherein: R₁ is selected from -(CH₂) x -, - (CH₂O) y CH₂-, -(CH₂) x OCH₂-, wherein x and y are integers within the range of from 1 to 4; m and n are integers, wherein the m/n ratio is within the range of from 0.2 to 2, preferably within the range of from 0.5 to 1.2; R f is a perfluoroalkylene radical; X if -F or -CF₃; Y represents an -OH and/or a -COOH group; and k, j, w, u, d, b, r, c, v, z, a, g are integers which make it possible for the above-mentioned molecular weights to be obtained.

Claim 7

Aqueous dispersions according to claim 5, wherein the hyd­roxy- and/or carboxy-capped fluoropolyethers are α,ω-bis­(hydroxymethyl)-polyoxyperfluoroalkylene and α,ω-(polyoxy­perfluoroalkane)-dioic acid, having an average molecular weight of about 2 000.

Claim 8

Stable aqueous dispersions of fluorinated polyurethanes con­taining in their macromolecule hydrophilic ionic groups, of either anionic or cationic nature, obtainable by means of the following steps: (i) preparation of a fluorinated polyisocyanate prepoly­mer by reacting an organic diisocyanate with a mixture comprising diols containing ionizable groups and mac­roglycols comprising polyols and at least 1 % by weight of one or more hydroxy- and/or carboxy-capped fluoropolyethers; (ii) conversion of the fluorinated polyisocyanate prepoly­mer into an oligo-urethane having unsaturated vinyl end groups, by reacting a compound containing hydro­xyl groups reactive with the isocyanate groups selec­ted from hydroxyalkyl-acrylates or -methylacrylates having the formula: wherein R₂ is hydrogen or a (C₁-C₄)-alkyl radical and W is a hydroxyalkyl radical; (iii) salification of the oligo-urethane obtained to con­vert the ionizable groups into hydrophilic cations or anions; (iv) dispersion of the salified oligo-urethane in water; and (v) polymerization of the unsaturated end groups of said oligo-urethane dispersed in water.

Claim 9

Stable aqueous dispersions of fluorinated polyurethanes con­taining in their macromolecule hydrophilic ionic groups, of either anionic or cationic nature, obtainable by means of the following steps: (i) preparation of a fluorinated polyisocyanate prepoly­mer by reacting an organic diisocyanate with a mixture comprising diols containing ionizable groups and mac­roglycols comprising polyols and at least 1 % by weight of one or more hydroxy- and/or carboxy-capped fluoropolyethers; (ii) conversion of the fluorinated polyisocyanate prepoly­mer into an oligo-urethane having unsaturated vinyl end groups, by reacting a compound containing hydro­xyl groups reactive with the isocyanate groups selec­ted from hydroxyalkyl-acrylates or -methylacrylates having the formula: wherein R₂ is hydrogen or a (C₁-C₄)-alkyl radical and W is a hydroxyalkyl radical; (iii) salification of the oligo-urethane obtained to con­vert the ionizable groups into hydrophilic cations or anions; (iv) dispersion of the salified oligo-urethane in water; and (v) polymerization of the unsaturated end groups of said oligo-urethane dispersed in water.

Claim 10

Aqueous dispersions according to claim 7, wherein the hyd­roxyalkyl-acrylates or -methacrylates are those wherein R is hydrogen or methyl, and W is 2-hydroxyethyl, 2-hydro­xypropyl, 3-hydroxypropyl or 4-hydroxybutyl.

Claim 11

Aqueous dispersions according to claim 7 or 8, wherein the hydroxyalkyl-acrylates or -methacrylates are used in such an amount so as to have NCO-eq/OH-eq ratios, in terms of the free isocyanate groups present in the polyisocyanate prepolymer, within the range of from 0.5 to 1.1, prefer­ably equal to 1.

Claim 12

Aqueous dispersions according to any one of claims 1 to 9, having a content of solids higher than 20 % by weight, preferably within the range of from 30 to 50 % by weight.

Claim 13

Aqueous dispersions according to any one of claims 1 to 10, wherein the fluorinated polyurethanes contain in their macromolecule ionic groups in an amount of from 10 to 60 milliequivalents per 100 g of dry polymer, preferably of from 20 to 40 meq/100 g of dry polymer.

Claim 14

A process for preparing woven and non-woven textile ar­ticles comprising treating said textile articles by means of aqueous dispersions of fluorinated polyurethanes ac­cording to any one of claims 1 to 11.

Claim 15

A process according to claim 12, wherein the aqueous dis­persions of fluorinated polyurethanes are applied by coat­ing them on the textile articles in a dry-deposited amount of at least 20 g/m², and preferably 20 to 40 g/m².

Claim 16

A process according to claim 12 or 13, wehrein the textile articles are on the basis of natural, artificial or synthe­tic fibers, such as wool, silk, cotton, flax, cellulosic fibers, acrylic, polyester or polyamide fibers,

Claim 17

Woven and non-woven textile articles that have been trea­ted with stable aqueous dispersions as defined in any one of claims 1 to 11.

Claim 18

Woven and non-woven textile articles on the basis of natu­ral, artificial or synthetic fibers, such as wool, silk, cotton, flax, cellulosic fibers, acrlyic, polyester or polyamide fibers, treated with stable aqueous dispersions as defined in any one of claims 1 to 11.

Claim 19

Woven and non-woven textile articles according to claims 15 or 16 endowed with contemporaneously high impermeabi­ lity and breathability, having a permeability to water vapor within the range of from 900 to 1 600 ng/s.m²·Pa and impermeability to water of higher than 24 hours under 2 meters water column.