Methods for preparing stable urea formaldehyde polyvinyl alcohol colloids
View Patent ↗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.
1. A method for preparing a polyvinyl alcohol and urea-formaldehyde colloid comprising:
admixing polyvinyl alcohol with a component selected from the group consisting of:
a solution of formaldehyde, and
a 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; and
subjecting the reaction product admixture to reaction conditions sufficient to initiate a condensation to form a polyvinyl alcohol and urea-formaldehyde resin colloid.
2. The method of claim 1 further comprising completing the process by making a urea post addition.
3. The method of claim 1 wherein the polyvinyl alcohol has a weight average molecular weight of from about 1,000 to about 200,000.
4. The method of claim 3 wherein the polyvinyl alcohol has a weight average molecular weight of from about 1,000 to about 50,000.
5. The method of claim 1 wherein the methylolation reaction occurs at a temperature of about 80° C. and a pH of from about 8.5 to about 9.5.
6. The method of claim 5 wherein the pH is adjusted using triethylamine and triethanolamine.
7. A method for preparing polyvinyl alcohol and urea-formaldehyde colloid comprising:
admixing a component selected from the group consisting of:
a solution of formaldehyde, and
a urea/formaldehyde concentrate,
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;
subjecting the reaction product to reactions conditions sufficient to initiate condensation to from a condensation product admixture; and
admixing the condensation product admixture with polyvinyl alcohol to form a urea-formaldehyde resin colloid.
8. The method of claim 7 further comprising completing the process by making a urea post addition.
9. The method of claim 7 wherein the polyvinyl alcohol has a weight average molecular weight of from about 1,000 to about 200,000.
10. The method of claim 9 wherein the polyvinyl alcohol has a weight average molecular weight of from about 1,000 to about 50,000.
11. The method of claim 7 wherein the methylolation reaction occurs at a temperature of about 80° C. and a pH of from about 8.5 to about 9.5.
12. The method of claim 11 wherein the pH is adjusted using triethylamine and triethanolamine.
13. A method for preparing polyvinyl alcohol urea-formaldehyde resin colloid comprising:
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; and
repeating the further processing until the further processed polyvinyl alcohol and urea-formaldehyde resin colloid meets the predetermined standard.
14. The method of claim 13 wherein the polyvinyl alcohol has a weight average molecular weight of from about 1,000 to about 200,000.
15. The method of claim 14 wherein the polyvinyl alcohol has a weight average molecular weight of from about 1,000 to about 50,000.
16. The method of claim 13 wherein the polyvinyl alcohol and urea-formaldehyde resin colloid meets a turbidity standard.
17. The method of claim 16 wherein the polyvinyl alcohol and urea-formaldehyde resin colloid has a turbidity of less than about 200 nephlometric turbidity units.