S. Grelier et al., ATTEMPT TO PROTECT WOOD COLOR AGAINST UV VISIBLE-LIGHT BY USING ANTIOXIDANTS BEARING ISOCYANATE GROUPS AND GRAFTED TO THE MATERIAL WITH MICROWAVE, Holzforschung, 51(6), 1997, pp. 511-518
Antioxidants such as a phenolic UV absorber containing the benzotriazo
l-4'-hydroxy-5'-tert-butyl)phenylethane moiety, a polyethyleneglycol a
nd two Hindered Amine Light Stabilizers (HALS) were derivatized to inc
orporate an isocyanate function. These were grafted on Middle Density
Fiber (MDF) boards, fir (Abies grandis) and oak woods by microwave act
ivation without the need of any catalyst. The effect of the antioxidan
t grafting on the photodiscoloration of the materials was measured in
the CIE-LAB system and expressed by the color difference number Delta
E. The UV absorber was found the most efficient to photostabilize the
woods and its action was enhanced when it is used in conjunction with
the other additives.