Resin synthesis, wood adhesives

Straight urea-formaldehyde resins are used principally in the preparation of molding compositions and adhesives. As the name implies, the resin is made by reaction between urea and formaldehyde however, the synthesis process somewhat depends upon the end-use envisaged. The following process is for a wood adhesive resin, and illustrates the general procedures involved [10]. 

An introduction to the typical resin synthesis of a UF resin used as an adhesive for wood products and in industrial applications is given below. It constitutes a handy formulation for those who want to work in this field. It is not a low-formaldehyde-emission formulation. To 1000 parts by mass of 42% formaldehyde solution (methanol < 1%) are added 22% NaOH solution to pH 8.3 to 8.5,497 parts by mass of 99% urea, and the temperature raised in 50 min from ambient to 90°C while maintaining pH in the range 7.3 to 7.6 by small additions of 22% NaOH. The temperature is maintained at 90 to 91°C until the turbidity point is reached (generally another 15 to 20 min). The pH is then corrected to 4.8 to 5.1 by addition of 30% formic acid, and the temperature is raised to 98°C. The water tolerance point is reached in 18 min and the pH is then adjusted to 8.7. Vacuum distillation of the reaction water with concomitant cooling is then initiated. After distillation of the wanted amount of water to reach a resin content of 60 to 65%, the resin is cooled to 40°C, 169 parts by mass of second urea is added, the pH is adjusted to 8.5 to 8.7, and the resin is allowed to mature at 30°C for 24 to 48 h resin characteristics solids content, 60% density, 1.268 g/cm free HCHO, 0.4% viscosity, 200cP pH, 8. 

In addition lo its use in making resins and adhesives, phenol is also the starting material for the synthesis of chlorinated phenols and the food preservatives BHT (butylated hvdroxytoiuene) and BHA (butylated bydroxyanisole). Penta-chlorophenol, a widely used wood preservative, is prepared by reaction of phenol with excess CI2- The herbicide 2,4-D (2,4-dichlorophenoxyacetjc acid) is prepared from 2,4-dichlorophenol, and the hospital antiseptic agent hexa-chlorophene is prepared from 2,4,5-trichlorophenol. 

Uses Methyl alcohol is a clear, colorless liquid with a slight alcoholic odor. It is used in the synthesis of formaldehyde, methylamine, ethylene glycol, methacrylates, and as an industrial solvent for a number of products (e.g., inks, resins, adhesives, dyes for straw hats). Methyl alcohol is an important ingredient commonly used to prepare grease and dirt remover. It also is used in the manufacture of photographic films, plastics, celluloid, textile soaps, wood stains, coated fabrics, paper coatings, artificial leather, and other industrial products. 

Uses Solvent for dyes, nitrocellulose, resins, paints, inks, textile printing, lacquers, quick-dry varnishes, enamels, wood stains, thinners, cosmetics mutual solvent for mineral oil-soap and mineral oil-sulfbnated oil mixts. humectant soaps organic synthesis brake fluid diluent mfg. of plasticizers solvent, thinner in nail enamels ointment base, solvent, solubilizer, cosurfactant for pharmaceuticals in food-pkg. adhesives in paper/paperboard in contact with dry food Regulatory FDA 21CFR 175.105,176.180 USP/NF compliance SARA 313 reportable HAP Canada DSL... 

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