Utilization of kraft lignin in phenol/formaldehyde bonding resins for OSB
View Patent ↗A resin for OSB comprising an aqueous resole reaction product of phenol, formaldehyde, alkaline metal hydroxide or carbonate, urea and a degraded lignin polymer having 35-65% solids, a pH of 8-13 and a viscosity 50-1000 centipoises. The phenol and formaldehyde are present in a molar ratio of 1.5 to 3.4 moles formaldehyde to 1 mole phenol and are 40 to 85% of the total solids added to the mixture. In one embodiment they are 50 to 75% of the total solids added to the mixture. The alkaline metal hydroxide or carbonate are 5 to 20% of the total solids added to the mixture. Urea is 5 to 35% of the total solids added to the mixture. The degraded lignin is 5 to 20% of the total solids added to the mixture. A method for making the resin and a product using the resin.
1. An aqueous bonding resin having 35-65% solid content, the aqueous bonding resin being a mixture of the product of a reaction among phenol and formaldehyde, a group 1 alkaline metal hydroxide, a kraft liquor degraded lignin polymer and urea, the kraft lignin being mostly free of sulfonic acid groups,
the phenol and formaldehyde being 40 to 85% of the weight of the solids provided to the reaction, the mole ratio of formaldehyde to phenol being 1.5-3.5:1,
the group 1 alkaline metal hydroxide being 5 to 20% of the weight of the solids provided to the reaction,
the kraft liquor degraded lignin polymer being 5 to 20% of the weight of the solids provided to the reaction,
the urea being 5 to 35% of the weight of the solids provided to the reaction,
the pH of the aqueous bonding resin being 8 to 13,
the viscosity of the aqueous bonding resin being 50 to 1000 centipoises.
2. The aqueous bonding resin of claim 1 wherein the viscosity of the aqueous bonding resin is 100-500 centipoises.
3. The aqueous bonding resin of claim 1 wherein the viscosity of the aqueous bonding resin is 120 to 350 centipoises.
4. The aqueous bonding resin of claim 1 wherein the pH of the aqueous bonding resin is 10 to 12.5.
5. The aqueous bonding resin of claim 1 wherein the solids content is 45-60%.
6. The aqueous bonding resin of claim 1 wherein the formaldehyde to phenol molar ratio is 2-3:1.
7. The aqueous bonding resin of claim 1 wherein the metal in the group 1 metal hydroxide is sodium, potassium, lithium, rubidium, cesium or francium.
8. The aqueous bonding resin of claim 1 wherein the phenol and formaldehyde being 50 to 75% of the weight of the solids provided to the reaction.
9. A composite wood product comprising the aqueous bonding resin of claim 1 and wood particles or wood strands compressed under heat and pressure, wherein the aqueous bonding resin enables adhesion between the wood particles or wood strands.
10. The product of claim 9 wherein the product is a panel.
11. The product of claim 10 wherein the panel has a surface layer and the particles or strands are in the surface layer of the panel.