Amino resins applications

Paper laminates, TiCh pigments in, 25 28 Papermaking, 11 179, 287-288. See also Paper manufacture additives in, 15 98 amino resin applications, 2 644-648 asbestos applications, 3 311 calcium carbonate applications, 4 554-555... 

By far the bulk of amino resins are used in the woodworking industry for the manufacture of chipboard, plywood and as general glues and adhesives. Melamine-formaldehyde is an important component of decorative laminates. The amount of amino resins used for moulding applications is only of the order of 5% of the total. 

Of the various amino-resins that have been prepared, the urea-formaldehyde (U-F) resins are by far the most important commercially. Like the phenolic resins, they are, in the finished product, cross-linked (thermoset) insoluble, infusible materials. For application, a low molecular weight product or resin is first produced and this is then cross-linked only at the end of the fabrication process. 

The alkyd moulding compositions are used almost entirely in electrical applications where the cheaper phenolic and amino-resins are unsuitable. 

Unlike phenol-formaldehyde polymers, the amino resins are not themselves deeply coloured, but are of a naturally light appearance. They can be easily pigmented to give a variety of shades, which leads to application in uses where good appearance is highly valued, for example in decorative tableware, laminated resins for furniture, and modem white electrical plugs and sockets. 

Marine coatings Organic coatings for corrosion control Paint acrylic ester polymers, 7 388-389 adhesion, 7 90-92 advanced ceramic, 7 704-705 alkanolamines from olefin oxides and ammonia, 2 136 alkyd resins, 2.T67-168 amino acid resin applications, 2 635—637 anticorrosion, 25 134 anticorrosion metallic, 7 713-714... 

Applications The tensile strength and hardness of the amino resins have been somewhat better than... 

The distribution between the families varies from one area to another mainly for polyethylene, thermoplastic polyesters and amino resins. For these, the variation perhaps comes from a problem of identification in the statistics, as some may include significant applications that are outside the framework of this book. However, we can say that the five most used plastic families are thermoplastics. 

The amino resins or plastics, closely related to the phenolics in both synthesis and applications, are obtained by the polymerization of formaldehyde with urea (XXXVII) (/ = 4) or melamine (XXXVIII) (f — 6). Synthesis of the amino plastics can be carried out either in alkaline or acidic conditions [Drumm and LeBlanc, 1972 Nair and Francis, 1983 Updegraff, 1985]. Control of the extent of reaction is achieved by pH and temperature control. The prepolymer can be made at various pH levels depending on the reaction temperature chosen. Polymerization is stopped by cooling and bringing the pH close to neutral. Curing of the prepolymer involves heating, usually in the presence of an added acid catalyst. 

Commercially, urea is produced by the direct dehydration of ammonium carbamate, NH2COONH4, at elevated temperature and pressure. Ammonium carbamate is obtained by direct reaction of ammonia and carbon dioxide. The two reactions are usually earned out simultaneously in a high pressure reactor. Recendy, urea has been used commercially as a catde-feed supplement (see Feeds and feed additives). Other important applications are the manufacture of resins (see Amino RESINS and plastics), glues, solvents, and some medicinals. Urea is classified as a nontoxic compound. 

A related methylphosphate/phosphonate oligomer has primary alcohol end groups, and can coreact with amino resins to form a water-resistant flame retardant resin finish on paper or on textile substrates. The application of this oligomer with a coreactant methylolmelamine on cotton upholstery fabric can enable furniture covered with this fabric to pass the Consumer Product Safety Commission s proposed cigarette ignition test. 

Both aqueous polymer-based systems (latex), made by emulsion or dispersion polymerization, and oil-modified alkyd resin-based systems are still in wide use [781], Table 12.2 shows the composition of a typical water-based emulsion paint. There is a wide variety of coatings, ranging from broad applicability to highly specialized, including latexes, amino resins, isocyanates, epoxy resins, acrylic resins, polyester... 

Most FR formulations are not resistant to leaching by water. Therefore, there have been increased efforts to develop leach-resistant chemicals that can be impregnated into wood products for use in exterior or high-humidity applications. Some of the proposed leach-resistant systems include chemical combinations that form insoluble complexes, amino-resin systems, and monomers that polymerize in the wood. A common amino-resin system for exterior use is dicyandiamide phosphoric acid formaldehyde. Guanylurea phosphate-boric acid also is a commonly used organic phosphate salt for modern commercial FR wood. 

Another advantage of the amino-resin systems is their applicability to solid wood and wood-composite products. Cedar shingles were the first products treated with this type of fire-retardant system (99, 100, 113, 114). Commercially treated shingles available in the U.S. are based on these systems. Generally, these systems exhibit good durability to outdoor weathering when tested over extended periods (115-17). 

Formaldehyde emission from particleboard has been studied at our laboratory for over 15 years. We search for an answer to the following question Given the fact that amino-resin bonded wood products have the ability to release formaldehyde into indoor air when they are in use, what simple and rapid analysis method can be used at the time of manufacture to predict formaldehyde release under use conditions as quantitatively as possible Obviously, the chosen method needs to be applicable for all types of boards that are available on the market. 

Although the chemistry of the reaction of formaldehyde with urea and other amino compounds was investigated much earlier, the first useful product did not come on the market until the 1920s. The first commercial application for amino resins was in molding compounds and utilized a resin made with an equimolar combination of urea and thiourea, the invention of Edmond C. Rossiter ( ). The Beetle brand name was applied to the new molding compound and has remained prominent in amino resins ever since. It is of special interest that the very first commercial product based on amino resins should be a complex formulation such as a molding compound. 

The simple methylol compounds and the low molecular weight polymers obtained from urea and melamine are soluble in water. They are quite suitable for the manufacture of adhesives, molding compounds, and some kinds of textile treating resins. However, amino resins for coating applications require compatibility with the film-forming polymer resins with which they must react. Furthermore, even where compatible, the free methylol compounds are often too reactive and too unstable for use in a coating formulation that may have to be stored for some time before use. Reacting the... 

Since both the amino resin and the polymer have multiple reactive sites, application of sufficient heat will yield a cross-linked structure with the degree of cure depending on the functionality of the system and on how far to the right the reaction (24) is driven. 

The selected example, by Baldwin et al. [36], showed the application of this technique to a small-molecule, nonoligomeric, large organic library of dihydrobenzopyrans (six steps over 85,000 members). The synthetic scheme for some among the prepared sublibraries is reported in Figure 10. The first monomer set (seven amines) was condensed in solution to a bromophotolinker, then the construct was hooked onto TentaGel amino resin (step A). After TFA deprotection, the resin-bound secondary amines were coupled to the second monomer set (two subsets, six carboxylic acids, step B), prepared by condensa-... 

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