Phenol formaldehyde consumption

In 1993, worldwide consumption of phenoHc resins exceeded 3 x 10 t slightly less than half of the total volume was produced in the United States (73). The largest-volume appHcation is in plywood adhesives, an area that accounts for ca 49% of U.S. consumption (Table 11). During the early 1980s, the volume of this apphcation more than doubled as mills converted from urea—formaldehyde (UF) to phenol—formaldehyde adhesives because of the release of formaldehyde from UF products. Other wood bonding applications account for another 15% of the volume. The next largest-volume application is insulation material at 12%. 

A third reason for predicting very low emissions of formaldehyde from phenolic panels is that the cured resin is extremely stable and does not break down to release additional formaldehyde, even under extremely harsh environmental conditions ( ). The high resistance of phenolic resins to deterioration under severe service conditions is, of course, a principal reason they are used so widely in making exterior types of wood panel products. Because of their chemical stability the U.S. Environmental Protection Agency has declared that phenol formaldehyde resins represent a consumptive use of formaldehyde, meaning that formaldehyde is irreversibly consumed in its reaction with phenol so that the formaldehyde loses its chemical identity (3). 

The main commercial thermosets are urea-formaldehyde resins (UF), melamine-formaldehyde resins (MF), phenol-formaldehyde resins (PF), epoxy resins, unsaturated polyesters, alkyd resins and polyurethanes. Changes in thermoset consumption in Western Europe during the period 1994-1996 are shown in Table 1.2. UF/MF resins and polyurethanes are produced in the greatest quantities, making up about 70% of the total thermosets market. 

The formaldehyde addition is rate controlling, with the reaction going rapidly and predominantly to the formation of methylene bridges. The formaldehyde addition rate is at a minimum at a pH of 4-5 and increases as the pH is either reduced or increased. The rate of formaldehyde consumption is dependent upon the pH and is relatively insensitive to the anion used. Initially, the reaction is approximately second order. If sufficient formaldehyde is present, the resin gels therefore under these conditions less than one mole of formaldehyde must be used per mole of phenol. The resulting product is a thermoplastic resin with a molecular weight dependent on the ratio of reactants. 

The presence of numerous hydroxyl groups able to react with formaldehyde makes starch-derived products suitable chemicals for formaldehyde-based resins. Research on this subject started many years ago and showed that in a number of applications it is possible to partially replace or extend urea formaldehyde, phenol formaldehyde and melamine formaldehyde resins without significantly affecting the finished product s performance. In many applications, adhesive systems based on formaldehyde resins incorporate a polysaccharide component. More than 4.5 Mio mto of formaldehyde-based resins have been produced in Western Europe alone. The use of carbohydrates allows lower consumption of oil-based resins and, consequently, reduced release of formaldehyde in the environment. 

As we know that phenol-formaldehyde (PF) resins were the first completely synthetic commercial polymer. Lignin constituted hy structure of three primary phenylpropane monomers can replace phenolic compounds in the synthesis of phenol-formaldehyde (PF) resins. Besides its use in polyurethanes and polyesters, technical lignins are also of interest in phenolic and epo Q resins. Kraft lignin can be used to displace up to 70% of the phenol required for PF resins, which can greatly decrease the raw material consumption. 

The most important commercial chemical reactions of phenol are condensation reactions. The condensation reaction between phenol and formaldehyde yields phenoHc resins whereas the condensation of phenol and acetone yields bisphenol A (2,2-bis-(4-hydroxyphenol)propane). PhenoHc resins and bisphenol A [80-05-7] account for more than two-thirds of U.S. phenol consumption (1). 

Phenohc resins are produced by the condensation of phenol or a substituted phenol, such as cresol, with formaldehyde. These low cost resins have been produced commercially for more than 100 years and in the 1990s are produced by more than 40 companies in the United States. They are employed as adhesives in the plywood industry and in numerous under-the-hood appHcations in the automotive industry. Because of the cycHc nature of the automotive and home building industry, the consumption of phenol for the production of phenohc resins is subject to cycHc swings greater than that of the economy as a whole. 

Formaldehyde is an important chemical in the plastics industry, being a vital intermediate in the manufacture of phenolic and amino resins. It was also used by Reppe during World War II as an important starting point for the preparation of a wide range of organic chemicals. Consumption of formaldehyde in acetal resins is still a minor outlet for the material but exceptionally pure material is required for this purpose. 

Uses. Furfuryl alcohol is widely used as a monomer in manufacturing furfuryl alcohol resins, and as a reactive solvent in a variety of synthetic resins and applications. Resins derived from furfuryl alcohol are the most important application for furfuryl alcohol in both utility and volume. The final cross-linked products display outstanding chemical, thermal, and mechanical properties. They are also heat-stable and remarkably resistant to acids, alkalies, and solvents. Many commercial resins of various compositions and properties have been prepared by polymerization of furfuryl alcohol and other co-reactants such as furfural, formaldehyde, glyoxal, resorcinol, phenolic compounds and urea. In 1992, domestic furfuryl alcohol consumption was estimated at 47 million pounds (38). 

The world wide consumption in 1997 of urea- and melamine-formaldehyde resins was 8xl06 nr phenolic resins 2.8 xlO6 m UP-resins 2.9 xlO6 t and EP-resins 1.5 x 106 t. 

Phenolic Vapours of formaldehyde and phenol may be emitted because of the vapour pressure of these constituents. But, as the polymerisation occurs at ambient temperature, these vapour pressures are low and given the consumption rates, the emissions are insignificant... 

Most of the glulam beams produced in Europe for load-bearing timber structures use melamine-urea-formaldehyde (MUF) and phenol-resorcinol-formaldehyde (PRF) adhesives. Nevertheless, PRF consumption has been decreasing continuously for several years because of the colour of the joints obtained, increased productivity requirements and environmental issues. 

Furan resins are also a low-volume consumption resin like amino resins, and are used as supplements to phenolic resins [33,34]. They are prepared by the reaction between a phenol and furan compounds such as furfural, furfuryl alcohol, and furan. Furan compounds can be used in place of formaldehyde in the conventional production of phenolic resins. The most popular and viable furan resins are prepared from furfuryl... 

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