Methods for preparing stable urea formaldehyde polyvinyl alcohol colloids

摘要

The mechanical properties of urea formaldehyde resins may be improved by incorporating therein polyvinyl alcohol. The polyvinyl alcohol may be incorporated during pre-mixing, mid mixing, and/or post mixing of the resin components. Resins prepared using polyvinyl alcohol are particularly desirable in articles requiring improved mechanical strength and water resistance, as compared to similar resins prepared without the polyvinyl alcohol such as shingles.

主权项

1. A binder prepared using a method selected from the group consisting of:
(A) admixing polyvinyl alcohol with a component selected from the group consisting of:
a solution of formaldehyde, anda urea/formaldehyde concentrate, to form a first liquid working admixture and then
admixing the first liquid working admixture with urea under reaction conditions sufficient to initiate a methylolation reaction to form a reaction product admixture of the first liquid working admixture with urea; andsubjecting the reaction product admixture to reaction conditions sufficient to initiate a condensation to form a polyvinyl alcohol and urea-formaldehyde resin colloid; (B) admixing a component selected from the group consisting of:
a solution of formaldehyde, anda urea/formaldehyde concentrate,with urea under reaction conditions sufficient to initiate a methylolation reaction to form a reaction product admixture;subjecting the reaction product admixture to reactions conditions sufficient to initiate condensation to form a second reaction product admixture; andadmixing the second reaction product admixture with polyvinyl alcohol to from a urea-formaldehyde resin colloid; and (C) adding polyvinyl alcohol to a urea-formaldehyde resin under reaction conditions sufficient to condense the polyvinyl alcohol and the urea-formaldehyde resin to produce a polyvinyl alcohol and urea-formaldehyde resin colloid wherein the addition of polyvinyl alcohol is at a concentration sufficiently low to be compatible with the urea-formaldehyde resin solution into which it is being placed;
measuring a property of the polyvinyl alcohol grafted urea-formaldehyde resin;determining whether the property of the polyvinyl alcohol grafted urea-formaldehyde resin meets a predetermined standard and taking an action selected from the group consisting of:
(a) if the property of the polyvinyl alcohol grafted urea-formaldehyde resin meets the predetermined standard, stop processing; and(b) if the property of the polyvinyl alcohol grafted urea-formaldehyde resin does not meet the predetermined standard, further processing the polyvinyl alcohol grafted urea-formaldehyde resin, the further processing comprising:
adding additional polyvinyl alcohol to the polyvinyl alcohol and urea-formaldehyde resin colloid under reaction conditions, sufficient to condense the polyvinyl alcohol and the polyvinyl alcohol and urea-formaldehyde resin colloid to produce a further processed polyvinyl alcohol and urea-formaldehyde resin colloid wherein the addition of polyvinyl alcohol is at a concentration compatible with the polyvinyl alcohol and urea-formaldehyde resin colloid into which it is being placed;measuring a property of the further processed polyvinyl alcohol and urea-formaldehyde resin colloid;comparing the property of the further processed polyvinyl alcohol and urea-formaldehyde resin colloid to a predetermined standard; andrepeating the further processing until the further processed polyvinyl alcohol and urea-formaldehyde resin colloid meets the predetermined standard.