Patent GB-1516018-A (GB)
Title: Water-dispersible polyurethanes
IPC: C08G18/80
Filed: 1976-12-08
Abstract: 1516018 Water-dispersible polyurethanes BAYER AG 8 Dec 1976 [10 Dec 1975] 51180/76 Heading C3R A non-ionic water-dispersible polyurethane has a substantially linear molecular structure and lateral polyalkylene oxide polyether chains, from 40-95% of the number of alkylene oxide units of the said chains being ethylene oxide units and from 5-60% being propylene oxide, butylene oxide or styrene oxide units, the content of ethylene oxide generally being from 3-30% wt. A preferred process for preparing the polyurethane comprises reacting at least one organic diisocyanate with at least one difunctional organic compound in the context of the isocyanate polyaddition reaction which contains terminal isocyanate-reactive hydrogen atoms and has a molecular weight of from 300 to 6000, and optionally one or more chain extenders having a M.Wt. below 300, the reaction being carried out in the presence of one or more synthesis components containing hydrophilic groups selected from diols of the general formula and/or diisocyanates of the general formula wherein R is a difunctional radical obtained by removing the NCO group from a diisocyanate of M.Wt. 112-1000; R<1> is a hydrogen atom or a monofunctional C1-C7 hydrocarbon radical; X is a difunctional polyalkylene oxide radical having from 5-90 alkylene oxide units, of which based on their number from 40-95% are ethylene oxide units and from 5-60% are propylene oxide, butylene oxide or styrene oxide units; Y and Z each represents -O- or -NR<111>-, and R<11> and R<111> each represents a C1-C12 monofunctional hydrocarbon radical. Another method of preparing the polyurethane comprises reacting a preferably linear polyurethane elastomer with hydrophilic monoisocyanate of the formula Preferred difunctional organic compounds are dihydroxy polyesters, polylactones, polyethers and polycarbonates. Sutiable chain extenders are low M.Wt. diols, diamines, hydrazine and hydrazides. The polyurethanes may be prepared by a one-stage process or by a prepolymer process, in the presence or absence of solvents. The polyurethane elastomers obtained either in melt form or in the form of a solution can be converted into aqueous dispersion by mixing with water and distilling off any solvent. The dispersions may be blended with other dispersions, e.g. of polyvinyl acetate, polyethylene, polystyrene, polybutadiene, polyvinyl chloride, polyacrylate and of copolymers; and with fillers, plasticizers, pigments, carbon black and silica sols, aluminium, clay and asbestos dispersions; and ionic emulsifiers. In the examples aqueous dispersions of polyurethanes are prepared either (1) by reacting a 1,6-hexanediol polycarbonate, 3 - isocyanatomethyl - 3,5,5 - trimethyl cyclohexyl isocyanate, 1,6-hexane diisocyanate and an adduct prepared by reacting 1,6-hexane diisocyanate with a polyether prepared from n-butanol and ethylene oxide and propylene oxide in a molar ratio of 83 : 17 and then with bis-(2-hydroxyethyl)amine; then adding acetone and then 3 - aminomethyl - 3,5,5 - trimethylcyclohexylamine in water and finally hydrazine monohydrate; then adding water and distilling off the acetone; or (2) by reacting a polyester diol of ethylene glycol and adipic acid with 2,4 - diisocyanato-toluene and a solution of an allophanate diisocyanate in 2,4- diisocyanato-toluene prepared by reacting 2,4- diisocyanato-toluene with a polyether prepared from n-butanol and ethylene oxide and propylene oxide (71 : 29 molar ratio), followed by heating in the presence of 4-toluene sulphonic acid methyl ester and zinc acetylacetonate and then adding benzoyl chloride; then adding acetone, then aqueous diaminoethane and then water and finally distilling off the acetone. Uses.-Coatings; adhesives; sizing agents; laminating agents; and plasticizers.