Treated wet process hardboard
A method of delivering and retaining zinc borate within a wet process hardboard is disclosed wherein process parameters are controlled and the borate is included in the overlay slush process of wet board processing.
1. A method for producing a treated hardboard comprising:
a) creating a slush containing a borate, cellulose fiber, and lignin;
b) adjusting the pH of the slush to decrease the solubility of the borate to form overlay slush;
c) providing a wet fiber hardboard mat;
d) adjusting the pH of the wet fiber hardboard mat to create pH-controlled hardboard mat;
e) depositing the overlay slush on the top of the pH-controlled hardboard mat; and
f) applying vacuum pressure during step e) to create a treated hardboard.
2. The method of claim 1 wherein the borate of step a) is zinc borate.
3. The method of claim 1 wherein the borate of step a) is selected from the group consisting of sodium borate, calcium borate and combinations thereof.
4. The method of claim 1 wherein the pH of the overlay slush of step b) is of from about 4.0 to about 10.0.
5. The method of claim 4 wherein the pH of the overlay slush of step b) is of from about 7.0 to about 8.0.
6. The method of claim 1 wherein the pH of the pH-controlled hardboard mat of step d) is of from about 2.0 to about 6.0.
7. The method of claim 6 wherein the pH of the pH-controlled hardboard mat of step d) is of from about 4.0 to about 5.0.
8. The method of claim 1 wherein the slush of step a) further comprises a phenol-formaldehyde resin.
9. The method of claim 8 wherein the resin is at most at about 2% dry weight of the slush.
10. The method of claim 1 wherein the fiber is of from about 75% to about 100% non-coarse fiber of the total fiber present.
11. The method of claim 10 wherein the fiber is of at least about 86% non-coarse fiber of the total fiber present.
12. The method of claim 1 wherein the pH-controlled hardboard mat of step e) is at a temperature of from about 43° C. to about 60° C.
13. The method of claim 12 wherein the temperature is of from about 48° C. to about 55° C.
14. The method of claim 1 wherein the overlay slush of step e) is at a temperature of from about 15° C. to about 33° C.
15. The method of claim 14 wherein the temperature is of from about 21° C. to about 24° C.
16. The method of claim 1 further comprising step g) wherein the treated hardboard undergoes a finishing process and creates a dust byproduct.
17. The method of claim 16 wherein the dust byproduct is recycled and used in forming the slush of step a).
18. A method for producing a treated hardboard comprising:
a) creating a slush containing a borate, resin, fiber, and water;
b) adjusting the pH of the slush to a range of from about 4.0 to about 10.0 to form overlay slush;
c) providing a wet fiber hardboard mat;
d) adjusting the pH of the wet fiber hardboard mat of from about 2.0 to about 6.0 to create a pH-controlled hardboard mat;
e) depositing the overlay slush with a temperature of from about 21° C. to about 24° C. on the top of the pH-controlled hardboard mat;
f) applying vacuum pressure during step e) to create a treated hardboard; and
g) finishing the treated hardboard.
19. The method of claim 18 wherein the pH of the overlay slush of step b) is within a range of from about 7.0 to about 8.0.
20. The method of claim 18 wherein the pH of the pH-controlled wet fiber hardboard mat substrate of step d) is within a range of from about 4.0 to about 5.0.