Polyurethane-based thickeners

Details Polyurethane-based thickeners Polyurethane-based thickeners

1994-05-10

1996-03-19

Michl, Paul R.

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...

524507, 524839, 528 60, 528 65, 528 73, C08J 300, C08K 320, C08L 7500, C08G 1828

Patent

active

055004750

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates to thickeners based on an aqueous preparation of nonionic, water-dispersible or water-soluble polyurethanes, to their production and to their use.
2. Discussion of Related Art
Associative polyurethane-based thickeners are linear or branched nonionic polymers with hydrophilic and hydrophobic segments. They are being increasingly used as a substitute for or in addition to the cellulose ethers traditionally used as thickeners in paints and lacquers and also the alkali-soluble polyacrylates. Polyurethane thickeners have the following advantages over these traditional thickeners: shear, substantially newtonian flow behavior.
Polyurethane thickeners of the type in question belong to the prior art. Their composition, production and use are described, for example, in U.S. Pat. No. 4,155,892. According to this document, the polyurethanes are produced by reaction of the following components: compounds containing an isocyanate-reactive hydrogen atom and organic monoisocyanates and
U.S. Pat. No. 4,079,028 relates to similar subject matter.


SUMMARY OF THE INVENTION

The problem addressed by the present invention was to provide polyurethane-based thickeners which would show a distinct improvement in the above-mentioned advantages of polyurethane thickeners over the polyurethane thickeners known from the prior art. More particularly, an increase in the viscosity of the thickened product would be obtained with the same quantity of thickener despite the relatively low intrinsic viscosity of the thickeners in their made-up form. In addition, a further approximation to newtonian flow behavior would be achieved. In addition, there would be no need to use solvents in the production of the thickeners.
According to the invention, this problem has been solved by thickeners based on an aqueous preparation of nonionic, water-dispersible or water-soluble polyurethanes obtainable by reaction of other polar group.


DETAILED DESCRIPTION OF THE INVENTION

As already mentioned, polyurethane-based thickeners belong to the prior art, cf. for example U.S. Pat. No. 4,155,892. The main difference between this U.S. patent and the present application is that the at least monofunctional, hydrophobic organic compound containing an isocyanate-reactive hydrogen atom is replaced in accordance with the present invention by monohydric alcohols containing at least one other polar group. A group is polar when its characteristic electron distribution provides the molecule with a considerable electrical dipole moment. It preferably contains at least 2 hetero atoms. Whereas the hydroxyl group of the monohydric alcohols is reactive to isocyanates, the additional polar groups are not intended to show such reactivity. Except for this difference, all other disclosures in U.S. Pat. No. 4,155,892 largely apply to the present application also, so that this U.S. patent must be counted as part of the disclosure of the present application.
Suitable polyether polyols (b) are, for example, the polymerization products of ethylene oxide, propylene oxide and/or butylene oxide, copolymerization or graft polymerization products thereof and polyethers obtained by condensation of polyhydric alcohols or mixtures thereof and polyethers obtained by alkoxylation of polyhydric alcohols, amides, polyamides and aminoalcohols. These polyether polyols are preferably so strongly hydrophilic that they are soluble in water. Polyether polyols at least predominantly containing polyalkylene glycols, more particularly polyethylene glycol and/or polypropylene glycol, are particularly suitable for the production of the polyurethanes according to the invention. Particularly good results are obtained when these polyalkylene glycols have an average content of alkoxy units of 20 to 400 and, more particularly, in the range from 160 to 210. If the suitable diols have the following general formula: ##STR1## n may assume a value of 20 to 400 and R.sup.1 may be H or CH.sub.3.
Diols in which R=H and n=130 to 230 and, more

REFERENCES:
patent: 4079028 (1978-03-01), Emmons et al.
patent: 4155892 (1979-05-01), Emmons et al.
patent: 4499233 (1985-02-01), Tetenbaum et al.

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