Modified wood product and a process for producing said product
The present invention relates to a process for preparing a modified wood product wherein the wood is treated with low-molecular weight resin based on lignin degradation products. The present invention also relates to a modified wood product produced using said process.
1. A process for preparing a modified wood product, comprising the steps of:
a) providing lignin;
b) degrading the lignin into lignin cleavage products;
c) fractionating the lignin cleavage products;
d) selecting one or more fractions of lignin cleavage products;
e) preparing a phenol-formaldehyde resin comprising the selected lignin cleavage products, wherein a ratio of lignin cleavage products to phenol is at least 2:3;
f) treating wood with the phenol-formaldehyde resin comprising the selected lignin cleavage products to obtain a modified wood product,
wherein the phenol-formaldehyde resin of step e) is prepared by adding formaldehyde to a mixture comprising phenol and the legnin cleavage products.
2. The process according to claim 1 , wherein the lignin is degraded by using sodium hydroxide as catalyst or by using a catalyst and microwave energy.
3. The process according to claim 1 , wherein the lignin cleavage products are chemically modified before step c) by hydroxymethylation.
4. The process according to claim 1 , wherein the wood has a moisture content of about 12%.
5. The process according to claim 1 , wherein the lignin is kraft lignin.
6. The process according to claim 1 , wherein the wood has been thermally modified prior to modification with the phenol-formaldehyde resin comprising the selected lignin cleavage products.
7. The process according to claim 1 , wherein the wood is densified during or after treatment with the phenol-formaldehyde resin comprising the selected lignin cleavage products.
8. A modified wood product obtained by the process according to claim 1 .
9. The modified wood product according to claim 8 , wherein the wood is a softwood or hardwood.
10. The process of claim 1 further comprising:
manufacturing cladding, decking, window and door profiles, light poles, jetties, joinery or furniture with the modified wood product.
11. The process of claim 1 further comprising:
chemically modifying the selected lignin cleavage products prior to preparing the phenol-formaldehyde resin.