Patent GB-351082-A (GB)
Title: Process for the production of vinyl ester resins
IPC: C08F8/28
Filed: 1930-03-25
Abstract: Polymerization products.-Resinous substances are produced by reacting an aldehyde with a partially or completely hydrolysed vinyl ester polymer or with a similarly-hydrolysed reaction product of an aliphatic vinyl ester and a saturated aliphatic aldehyde.  The said polymer or reaction product may be hydrolysed before reacting with the aldehyde, or the hydrolysis and reaction with the aldehyde may be caused to proceed simultaneously.  The aldehyde which is caused to react with the hydrolysed polymer or reaction product may be an aliphatic aldehyde such as acetaldehyde or crotonaldehyde, or an aldehyde such as benzaldehyde or furfural may be used.  The resinous products obtained are stated to vary in character according to (1) the proportion of aldehyde employed in the preparation of the esteraldehyde gum; (2) the extent of the hydrolysis; (3) the amount and character of the aldehyde taking part in the final reaction; and (4) the character and amount of the acid catalyst used.  In general, the final resinous products p  are much harder and tougher than the reaction products obtained from aliphatic vinyl esters and a saturated aliphatic aldehyde prepared according to Specifications 280,246 and 295,322, [both in Class 2 (iii), Dyes &c.].  The following examples are described: (1) Vinyl acetate-aldehyde gum obtained by reacting vinyl acetate with aldehyde is dissolved in ethyl alcohol.  Formaldehyde solution and hydrochloric acid are added and the whole reacted in a closed autoclave at 100 DEG  C.  After the recovery of the solvent and ethyl acetate and removal of acid the product recovered when dried forms a good moulding resin.  (2) Less acetaldehyde is used than in the previous example, a harder and tougher resin being obtained.  According to example (8), an increased proportion of acetaldehyde is specified, the resulting resin having a lower softening point.  In example (6), acetaldehyde is substituted for formaldehyde in the secondary reaction; the product is strong and tough.  Hydrolysis and the secondary aldehyde reaction takes place simultaneously in the foregoing examples; in the following examples the resin formation is conducted in a two-stage process: (3) The gum obtained according to example (1) is refluxed with several times its weight of water containing hydrochloric acid until hydrolysis reaches 60 per cent.  The resulting hydrolysed gum is dissolved in alcohol and reacted under reflux with formaldehyde solution containing hydrochloric acid for 4 hours; (4) and (5) A gum used in the previous example is completely hydrolysed and caused to react with acetaldehyde.  In the following examples partially or completely hydrolysed polymerized vinyl esters are caused to react with aldehydes: (9) Polymerized vinyl acetate is dissolved in acetone, water and hydrochloric acid added, and the reagents heated in a closed vessel at 100 DEG  C. for several hours.  The product may then be reacted with an aldehyde.  (10) Dry polymerized vinyl acetate is heated with about twice its weight of water containing hydrochloric acid, for 15 hours, the material being thereby hydrolysed to the extent of 86 per cent; it is then reacted with aldehyde.