Phenol-formaldehyde wood panel products bonded

Formaldehyde Release from Wood Panel Products Bonded with Phenol Formaldehyde Adhesives... 

EMERY Wood Panel Products Bonded w ith Phenol Formaldehyde Adhesives 31... 

Wood-based panel products are usually bonded with synthetic adhesives based on condensates of phenol, resorcinol, urea, or melamine with formaldehyde. Particleboards and fiberboards can also be bonded with mineral binders like cement or gypsum. Wood adhesives derived from natural products have more... 

Particleboard and other products made with isocyanates emit only little formaldehyde (IJ, but these adhesives are expensive and require expensive manufacturing procedures. In contrast, phenolic soft wood plywood is a well established product that is predominantly used for exter i or appIi cat i ons. It conta i ns forma Idehyde i n chemically strongly bonded form and also emits little formaldehyde, as shown in a later chapter in this book. In fact, under almost all common use conditions this type of board contributes not much more formaldehyde than is already present in ambient air in many urban areas. The same is true for waferboard, which has recently become popular for replacing plywood. Likewise, phenolic particleboard emits little forma Idehyde, unIess the phenoIi c res in is bIended w i th UFR. Normally, the products with highest potential for formaldehyde emission are those bonded with UFR. During the past year, approximately 300,000 metric tons of UFR have been used for panel manufacturing in the U.S. 

Lines of demarcation between hardwood plywood, softwood plywood and certain other wood based panel products have become less distinct in recent years. One of the most important distinctions in respect to formaldehyde emission potential is that softwood plywood is typically bonded with phenol-formaldehyde while hardwood plywood is typically bonded with urea-formaldehyde. Phenol-formaldehyde adhesives are more stable and have less tendency to emit formaldehyde than do urea-formaldehyde adhesives. Some important features of hardwood plywood ... 

The wood panels industry heavily relies on the use of synthetic resins and adhesives, as adhesively bonded products of one kind or another constitute about 80% of the wood products on the market today. In short, without adhesives and resins this industry would not exist [1,2]. Among these products a certain proportion of wood panels are manufactured for exterior, weather resistant application. Phenol-formaldehyde (PF) resins, and more recently, phenol-urea-formaldehyde (PUF) resins [3-8] are the most commonly used resins among the leading adhesives for exterior grade wood panels. 

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