Leo Baekelan P3 was awarded a US patent for the manufacture of laminates from fiber-phenolic resin compositions in 1912. Products made with thermosetting phenolic resins are much more water resistant than paper or steel. The fiber imparts flexibility and toughness to the brittle phenolic resin.
This finding led to the impregnation of saturated sheets or webs with novolac and then drying them to remove most of the solvent. Several sheets of paper-impregnated paper are stacked and heated and pressurized in a hydraulic press. The hot pressing causes the phenolic resin to be condensed (polymerized) and the loose paper stack is processed into a unitary laminate. The thickness of the laminate can be adjusted by varying the amount and basis of the paper stack. Changes in resin content and resin composition will change the physical properties of the laminate.
The rapid growth of the automotive and electrical industries provides ready-made market potential for all three products, including gears, gaskets and electrical insulation. In most cases, phenolic laminates achieve the required performance at a lower price, and they have completely driven other products out of the market.
Due to the brownish black color of the phenolic laminate, it can only be used in applications where aesthetic requirements are not important. Attempts have been made to dye phenolic laminates, but the results have not been effective until the melamine-formaldehyde resin was obtained after World War II. Thereafter, a laminate composed of a trimeric amine: formaldehyde resin impregnated paper and a phenolic resin impregnated core layer became a standard decorative laminate. After the Second World War, decorative plastic laminates (or decorative plastic panels) developed rapidly and they have now become the main plastic laminate products.
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