GB771155A - Polymers and dispersions thereof - Google Patents

Abstract

Polyvinyl acetals contain recurring intralinear <FORM:0771155/IV(a)/1> groups and groups of the formula <FORM:0771155/IV(a)/2> wherein R1 is a divalent organic radical of 1 to 10 carbon atoms having a carbon atom of a hydrocarbon nucleus attached to the <FORM:0771155/IV(a)/3> group and an acyclic -CH2- group attached to the N atom, R2 and R3 are alkyl radicals of 1-6 carbon atoms and R4 is a divalent saturated aliphatic hydrocarbon radical of 1-5 carbon atoms. They may be prepared by reacting a water-soluble or hydrophilic vinyl alcohol polymer having a large number of intralinear <FORM:0771155/IV(a)/4> groups with a betaine-containing aldehyde, or a monomeric acetal thereof formed with an alkanol of 1-4 carbon atoms or a 1:2 or 1:3 alkane diol of 2-4 carbon atoms, in the presence of an acid catalyst, or by preparing the monomeric acetal from the betaine-containing aldehyde and a monomeric alcohol, preferably ethylene glycol, and forming the polyvinyl acetal by acetal interchange with polyvinyl alcohol. The vinyl alcohol polymers are prepared by polymerizing a vinyl ester alone or with a minor proportion (10 per cent or less) of an unsaturated copolymerizable monomer, followed by partial or complete hydrolysis so as to produce at least 40 aliphatic hydroxyl groups per 100 chain atoms. The polymers may have a minor number of the hydroxyl groups modified with other groups, e.g. ether or ester groups. Dispersions of light-sensitive silver halides in these polyvinyl acetals form photographic emulsions. Specifications 535,341, 551,659, 598,477, [all in Group IV], 627,125, 635,294, 652,928, 662,793 and 747,801, [Group III], are referred to.ALSO:Betaine-aldehydes of general formula <FORM:0771155/IV(b)/1> where R1 is a divalent organic radical (preferably hydrocarbon or amide-interrupted hydrocarbon) of 1 to 10 carbon atoms having a carbon atom of a hydrocarbon nucleus attached to the -CHO group and an acyclic -CH2- group attached to the N atom, R2 and R3 are alkyl radicals of 1-6 carbon atoms, and R4 is a divalent saturated hydrocarbon radical of 1-5 carbon atoms, and acetals thereof. The aldehydes may be prepared by treating an aldehyde containing a tertiary amino group with a lactone such as b -propiolactone, or with an a - or b -chloroacid, such as chloracetic or b -chloropropionic, followed by removal of the halogen. A general procedure for preparation of betaines by the lactone method is given in J.A.C.S. 73, 3168 (1951). The aldehyde group can be converted into an acetal, e.g. the dimethyl acetal and ethylene glycol acetal. In an example m-aminobenzaldehyde ethylene glycol acetal in dioxane is mixed with aqueous sodium carbonate and stirred while adding a dioxane solution of chloroacetyl chloride. The m-(chloroacetamido) benzaldehyde ethylene glycol acetal is dissolved in benzene and gaseous dimethylamine introduced producing m - [(dimethylamino) acetamido] benzaldehyde ethylene glycolacetal which mixed with anhydrous ether and acetonitrile is stirred while a solution of b -propiolactone in anhydrous ether is slowly added. The betaine of the acetal results. Specifications 627,125, 635,294 and 652,928 are referred to.