Aqueous polyurethane acrylate hybrid dispersions

Patent metadata

Field	Value
Publication number	US-2017369750-A1
Application number	US-201715699250-A
Country	US
Kind code	A1
Filing date	Sep 8, 2017
Priority date	Mar 12, 2015
Publication date	Dec 28, 2017
Grant date	—

Abstract

The present invention relates to processes for the manufacture of aqueous polyurethane/acrylic hybrid dispersions that can be used as adhesives or coatings, are solvent free and have low VOC emissions, and are environmentally friendly. Also encompassed are the dispersions as such, compositions containing them and their use as coatings and adhesives.

First claim

1 . A process for manufacturing an aqueous polyurethane acrylate hybrid polymer dispersion, comprising:
(1) forming an NCO-terminated, vinyl-functionalized polyurethane prepolymer from a reaction mixture comprising:
(a) at least one polyol with a number average molecular weight M n in the range of 400 to 10000 g/mol, preferably 500 g/mol to 4000 g/mol;
(b) at least one vinyl-functionalized polyol;
(c) optionally at least one modified polyether polyol;
(d) at least one anionic stabilizer comprising at least two hydroxyl groups and at least one negatively charged functional group;
(e) at least one polyisocyanate, wherein the at least one polyisocyanate is used in molar excess relative to the hydroxy groups of the other components of the reaction mixture to obtain an NCO-terminated, vinyl-functionalized polyurethane prepolymer;
(2) dissolving the prepolymer obtained in step (1) in at least one acrylic monomer to obtain a prepolymer/acrylic monomer mixture, wherein the amount of the prepolymer and the at least one acrylic monomer is selected such that the weight proportion of polyurethane/acrylic in the hybrid polymer is 10:90 to 50:50; (3) dispersing the prepolymer/acrylic monomer mixture into a continuous aqueous phase under application of shear forces, to obtain an emulsion; (4) reacting the prepolymer with at least one chain extension agent; and (5) polymerizing the vinyl groups of the prepolymer and the at least one acrylic monomer to obtain the polyurethane acrylate hybrid polymer dispersion.

2 . The process according to claim 1 , wherein (i) the reaction mixture in step (1) and/or the at least one acrylic monomer in step (2), additionally comprises at least one (modified) polyolefin, polyacrylic or rosin-based resin; and/or (ii) a dispersion of at least one (modified) polyolefin, polyacrylic or rosin-based resin is incorporated into the continuous aqueous phase in step (3), wherein said (modified) polyolefin, polyacrylic or rosin-based resin comprises highly polar and highly unpolar segments that act as compatibilizers between the adhesive and the highly unpolar substrate.

3 . The process according to claim 1 , wherein the (modified) polyolefin, polyacrylic or rosin-based resin is selected from the group consisting of halogenated polyolefin resins, halogenated polyolefin maleic resins, polyolefin maleic resins, styrene/ethylene-butylene copolymer, styrene/butadiene copolymer, styrene/ethylene-propylene copolymer, styrene/isoprene copolymer, (meth)acrylate ester/(meth)acrylic acid copolymer, rosin-acid resins, and rosin-ester resins.

4 . The process according to claim 1 , wherein the process further comprises adding an organic co-solvent to the prepolymer/acrylic monomer mixture obtained in step (2) and dispersing the prepolymer/acrylic monomer/cosolvent mixture into a continuous aqueous phase and removing the cosolvent, after step (5).

5 . The process according to claim 4 , wherein
(1) the cosolvent is acetone; and/or (2) the cosolvent is used in an amount of up to 50 wt.-% relative to the total weight of the prepolymer/acrylic monomer/cosolvent mixture.

6 . The process according to claim 1 , wherein the at least one polyol (a) comprises at least one polybutadiene polyol and at least one polyester polyol, preferably in a weight ratio of 10:1 to 1:10.

7 . The process according to claim 1 , wherein the vinyl-functionalized polyol
(a) is a vinyl group-containing diol; and/or (b) is an allyl-functionalized polyol, preferably an polyol allyl ether, wherein the polyol allyl ether is preferably selected from monoethers of allyl alcohol with a polyol having three or more hydroxyl groups, preferably glycerol; and/or (c) is a monomeric polyol; and/or (d) has an average number molecular weight M n less than 400 g/mol.

8 . The process according to claim 1 , wherein the at least one anionic stabilizer comprises a sulfonated polyglycol and/or 2,2-bis(hydroxymethyl)propionic acid (DMPA).

9 . The process according to claim 1 , wherein
(1) the at least one polyisocyanate is used in molar excess relative to the hydroxy groups of the combined polyols, the OH/NCO equivalent ratio preferably being 1:1.1 to 1:4, and/or (2) the at least one polyisocyanate is at least one diisocyanate or triisocyanate, preferably selected from the group consisting of isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), polymeric polyisocyanates based on IPDI or HDI, and mixtures thereof.

10 . The process according to claim 1 , wherein each of the at least one acrylic monomers is selected from acrylate monomers, methacrylate monomers and mixtures thereof.

11 . The process according to claim 1 , wherein step (3) comprises emulsifying the polyurethane prepolymer/acrylic monomer mixture into a continuous aqueous phase, by mechanical stirring.

12 . The process according to claim 1 , wherein the chain extension agent comprises at least two NCO-reactive groups and is preferably selected from the group consisting of water, a diol or a diamine, more preferably hydrazine, an alkylene diamine, a cycloalkylene diamine, an alkyldiol, or a polyetherdiamine, and is optionally used in an amount that ensures essentially total conversion of the isocyanate groups.

13 . An aqueous polyurethane hybrid dispersion obtainable according to a process of claim 1 .

14 . The aqueous polyurethane hybrid dispersion of claim 13 , which is an adhesive.

15 . The aqueous polyurethane hybrid dispersion of claim 13 , which is a coating composition.

16 . The aqueous polyurethane hybrid dispersion of claim 14 , which is blended with at least one further rosin-based resin dispersion, at least one polyacrylic resin dispersion and/or at least one further (modified) polyolefin.

17 . The aqueous polyurethane hybrid dispersion of claim 15 , which is blended with at least one further rosin-based resin dispersion, at least one polyacrylic resin dispersion and/or at least one further (modified) polyolefin.

Assignees

• Henkel Ag & Co Kgaa

Inventors

• Zhao Ligang
• Sauca Sorin N
• Berges Christina

Classifications

• C08G18/755 Primary

  and at least one isocyanate or isothiocyanate group linked to a secondary carbon atom of the cycloaliphatic ring, e.g. isophorone diisocyanate · CPC title

• C09D175/04

  Polyurethanes · CPC title

• C08G2170/80

  Compositions for aqueous adhesives · CPC title

• C08G18/675

  Low-molecular-weight compounds · CPC title

• C08G18/6208

  Hydrogenated polymers of conjugated dienes · CPC title