Wood adhesives synthesis

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]. 

Anna Finne-Wistrand completed her doctoral degree in Polymer Technology 2003 at the Royal Institute of Technology (KTH), Sweden. After the completing her studies she worked in the wood adhesive industry. She resumed her academic career in 2005 at KTH as an Assistant Professor and, since 2010, as an Associate Professor in Polymer Technology. Her current research interest is focused on synthesis and fabrication of designed polymer scaffolds, the possibilities to direct cell function and tissue regeneration. 

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 Copolymerized with methyl acrylate, methyl methacrylate, vinyl acetate, vinyl chloride, or 1,1-dichloroethylene to produce acrylic and modacrylic fibers and high-strength fibers ABS (acrylonitrile-butadiene-styrene) and acrylonitrile-styrene copolymers nitrile rubber cyano-ethylation of cotton synthetic soil block (acrylonitrile polymerized in wood pulp) manufacture of adhesives organic synthesis grain fumigant pesticide monomer for a semi-conductive polymer that can be used similar to inorganic oxide catalysts in dehydrogenation of tert-butyl alcohol to isobutylene and water pharmaceuticals antioxidants dyes and surfactants. 

Finally, for practical reasons it is useful to classify polymeric materials according to where and how they are employed. A common subdivision is that into structural polymers and functional polymers. Structural polymers are characterized by - and are used because of - their good mechanical, thermal, and chemical properties. Hence, they are primarily used as construction materials in addition to or in place of metals, ceramics, or wood in applications like plastics, fibers, films, elastomers, foams, paints, and adhesives. Functional polymers, in contrast, have completely different property profiles, for example, special electrical, optical, or biological properties. They can assume specific chemical or physical functions in devices for microelectronic, biomedical applications, analytics, synthesis, cosmetics, or hygiene. 

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. 

Anastassiades, T.P. and Wood, A. (1981). Efiect of soluble products from lectin-stimulated lymphocytes on the growth, adhesiveness and glycosaminoglycan synthesis of cultured synovial fibroblast cells. J. Clin. Invest. 68, 792-802. 

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. 

There are many books about adhesives. Several excellent books are available that deal with the subject of adhesives from different points of view. Some have looked at adhesives from synthesis, chemistry, or bonding techniques points of view. Others have treated the subject from a practical standpoint. Of these, most are attempts to describe adhesion to a variety of materials including plashes, metals, wood, etc. A few books are highly specialized in the applicahons of adhesives in a particular industry such as metals or construchon. 

The development of a solvent-free, environmentally friendly, ethylene-vinyl acetate dispersion, called EVA2615 M, which can be used for general applications and is particularly suitable for wood and paper applications, is reported. The emulsion polymerisation technology employed for the synthesis of this EVA is described and the properties of the EVA dispersions, which are particularly suitable for applications requiring water resistance, are presented. (Feica - 2000 World Adhesives Conference Exhibition, Spain). 

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