| 摘要 |
The adhesive for producing plywood boards, chipboards and fibreboards and the like, which contains, as main components, phenol formaldehyde resin and lignin derivatives fractionated according to molecular weight, does not, as in the main patent, need to contain only those lignin derivatives of which at least 50% by weight have a molecular weight of over 5000. It is rather sufficient, in order to obtain weather-resistant adhesives of the aforementioned kind, if at least 35% by weight have a molecular weight of over 5000. This simplifies the production considerably. |
