Method for the Production of Wood Material Articles with Low Emissions of Chemical Compounds

Abstract

The invention relates to a method for production of wood material articles with low emissions of chemical compounds. The applied wood is treated with bisulfite before bonding. On using formaldehyde resins in the bonding agent, wood material articles can be produced with the inventive method with extremely low formaldehyde emissions and very bright colours.

Claims

1. A method for the production of a wood material article comprising: providing wood chips or wood fibres, treating said wood chips or wood fibres prior to a gluing process in saturated water vapour atmosphere or in saturated water vapour air for a duration of 3 to 8 minutes with bisulfite salt at a pressure of 6 to 12 bar, and gluing said wood chips or wood fibres together in a standard gluing process.

2. Method according to claim 1, wherein the wood chips or wood fibres are treated with the bisulfite salt in a cooker.

3. Method according to claim 1, wherein the wood chips or wood fibres are treated with the bisulfite salt in a refiner.

4. Method according to claim 1, wherein the bisulfite salt is chosen from the group consisting of sodium bisulfite and ammonium bisulfite.

5. Method according to claim 1, wherein the wood chips or fibres treated with bisulfite salt are glued together with an aminoplast resin.

6. Method according to claim 5, wherein the aminoplast resin is chosen from the group consisting of urea formaldehyde resin, melamine formaldehyde resin, urea-melamin formaldehyde resin and melamin urea phenol formaldehyde resin.

7. A wood material article, comprising wood chips or wood fibres glued together with an aminoplast resin, wherein the wood chips or fibres are, prior to the gluing process, treated with bisulfite salt in saturated watervapour atmosphere or in saturated watervapour air for a duration of 3 to 8 minutes at a pressure of 6 to 12 bar.

Description

EXEMPLARY EMBODIMENT

[0027] Two fibre boards S1 and V1 were produced with the above described method by using a formaldehyde-urea resin, having a molar ratio of formaldehyde to urea of 1:1.08, with the only distinguishing feature, that for the manufacturing of the fibre board V1 the hackled wood was not treated with bisulfite before the impregnation process. The treatment of the hackled wood with bisulfite was done at a pressure of 8.5 bar with an amount of bisulfite of 3 kg per m.sup.3 of hackled wood and for a duration of 3.5 minutes. After the pre-treatment of the wood, the wetting with a none-impregnation agent and after that the pressing was done.

[0028] In table 1 the perforation values (according to DIN EN 120wood materialsdetermination of formaldehyde content) of both fibre boards S1 and V1 are shown.

TABLE-US-00001 TABLE 1 Fibre board Perforation values in MCHO/100 g fibre board S1 2.5 V1 6.5

[0029] The values in table 1 show, that by treating the hackled wood with bisulfite wood material articles can be obtained, which show extremely low formaldehyde emissions. Further, the fibre board S1 emitted only extremely low amounts of other chemical compounds. Additionally, fibre board S1 was significantly brighter than fibre board V1.