Plywood QC Inspection Checklist : Part 36 Standard for adhesives for Wood-based Panels Industry
There are many occupational hazards in wood-based panel manufacturing enterprises, such as formaldehyde, dust, noise and other toxic and harmful substances.
Toxic and harmful substances mainly exist in adhesives, and occupational hazards mainly exist in the gluing and sizing processes. Wood and wood-based panel industrial adhesives are classified into urea-formaldehyde resin, phenolic resin, melamine-formaldehyde resin and so on according to the main synthetic materials.
(1) Urea-formaldehyde resin
According to the use, it can be divided into cold pressing, plywood and blockboard, particleboard, medium (high) density fiberboard and impregnation. Modified urea-formaldehyde resin with a small amount of melamine is also used in the production of E0 and E1 grade high density fiberboard and particleboard. The main raw materials are formaldehyde and urea, and the auxiliary materials are liquid alkali, formic acid, ammonia water, triethanolamine, ammonium sulfate, etc.
The main harm of urea-formaldehyde resin to human body is free formaldehyde. The standard requires that the content of free formaldehyde in urea-formaldehyde glue be less than 0.3%.
(2) Phenolic resin
It can be divided into impregnating and gluing according to its use. The main raw materials are phenol and formaldehyde, and the auxiliary materials are liquid alkali.
Free formaldehyde and free phenol are the main hazards of phenolic resin to human body. The standard requires that the free formaldehyde content of phenolic gum be less than 0.3% and the free phenol content be less than 6%.
Phenol is a colorless acicular crystal or white crystalline frit at room temperature. When skin is exposed to phenol aqueous solution or pure phenol, it will cause anesthesia poisoning and become ulcerated with strong corrosiveness.
(3) Melamine formaldehyde resin
It is mainly used for impregnation. The main raw materials are melamine and formaldehyde, and the auxiliary materials are liquid alkali, caprolactam, diethylene glycol and 1.4-butanediol.
The main harm of melamine formaldehyde resin to human body is free formaldehyde. The standard requires that the content of free formaldehyde in urea-formaldehyde glue be less than 0.3%.