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Urea Formaldehyde Adhesive

Thermosetting Resin Adhesive Article Contents: Thermosetting Resin Adhesive Melamine Formaldehyde Adhesives Urea Formaldehyde Adhesiv...

Saturday, May 24, 2008

The properties of phenol formaldehyde

Other adhesive as alternative of urea formaldehyde use is phenol formaldehyde. Phenolic glues are resistant to cold cured ones have a lower resistance to strong alkalies than the alkali cured glues, and quite naturally the converse applies; both type are resistant to all the common organic solvents. The properties of phenol formaldehyde...

Although phenolic glues are comparatively brittle, this is not a property of significant importance in many applications, for example, in plywood manufacture; nor in most wood gluing operations provided thick glue lines can be avoided. Dark color is often a disadvantage and the addition of a white pigment decreases it to only a limited extent.

Phenolic glues can be considered tolerant to most fungicidal chemicals; particular examples are sodium pentachlorophenate and isosafrole. In gluing wood, the moisture content of the timber is generally considered to be a more important factor than with urea glues. In this respect, greater latitude is claimed by dispersing, in a normal alkali condensed glue, a powdered phenolic resin condensate that is insoluble at room temperature but capable of swelling as the pressing temperature is reached.

The behavior of any type of adhesive depends in part on the material of which the adherents are made, sometimes to an appreciable extent. Durability is an important example of this. For example, phenolic metal adhesives in their operation at high temperatures are more durable on aluminum than on stainable steel, an aspect of durability that is discussed more fully in connection with the phenolic/epoxy adhesives. The durability of phenolic wood glues varies with different timbers; but factors such as glueline thickness can also have an effect. Investigations on the durability of phenolic glued wood joints have been made in England and in America.

Throughout the world the highest specifications for plywood, even if phenolic resins are not mentioned by name, are designed to make their use almost mandatory.