Types of amino resins

A large variety of melamine resins are commercially available, with important variables being type of amino compound, molar ratio of formaldehyde to amino compound, degree of polymerization, type of 

Based on the type of amino compound, the aminoplasts used in coatings are classified as four main types urea formaldehyde (UF), melamine formaldehyde (MF), benzoguanamine formaldehyde (BF) and glycouril formaldehyde (GF) resins. The majority of commercially used amino cross-linkers are MFs and UFs, with others used only for specialty applications. These resins vary in their characteristics as summarized below  

Highly alkylated Partially alkylated High imir o  

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Urea. Urea (carbamide) CH4N2O, is the most important building block for amino resins because urea—formaldehyde is the largest selling amino resin, and urea is the raw material for melamine, the amino compound used in the next largest selling type of amino resin. Urea is also used to make a variety of other amino compounds, such as ethyleneurea, and other cyclic derivatives used for amino resins for treating textiles. They are discussed later. 

Distinguishing between these two mechanisms is difficult however, recent evidence in the coating area suggests that the second route is important, especially for the cure of certain types of amino resins. 

Developments in coatings technology have been reflected in the types of amino resins used. Melamines have grown in general at the expense of ureas, and the higher solids, more monomeric melamines have grown at the expense of conventional polymeric melamines. 

Urea-formaldehyde (UF) adhesive resins as the most important type of amino resins were among the first commercially used adhesive systems and still dominate the production of wood based panels [8]. UF resins are based on the reaction of the two monomers urea and formaldehyde they consist of linear or branched oligomeric and polymeric molecules of various molar masses [9, 10]. The degree of condensation is one of the most important characteristics of condensation resins and determines several of their properties the viscosity at a certain solid content increases [11], and flowability and hence the equal distribution of the resin on the furnish (particles, fibers) and the penetration into the wood surface are hindered [12, 13]. 

Ethylene-urea resin n. A type of amino resin. 

Ethylene-Urea Resin n A type of AMINO RESIN. 

Hydroxy functional acrylics will cure with all types of amino resins, including urea formaldehyde, melamine formaldehyde (MF) and benzoguanamine formaldehyde types. Urea formaldehyde resins are faster curing and cheaper than the other two main types, but they are rarely used with acrylics due to inferior film performance (e.g. resistance properties and exterior durability). 

A wide selection of amino resin compositions is commercially available. They are all alkylated to some extent in order to provide compatibiUty with the other film formers, and formulation stabiUty. They vary not only in the type of amine (melamine, urea, ben2oguanamine, and glycolutil) used, but also in the concentration of combined formaldehyde, and the type and concentration of alkylation alcohol (/ -butanol, isobutyl alcohol, methanol). 

N -Protection as allyl carbamate is used generally only for specific synthetic purposes where acid- or base-mediated deprotection procedures must be avoided or reduced to a minimal extent as in the case in the synthesis of glyco- and phosphopeptides (see Sections 6.3 and 6.5). Otherwise the orthogonality of this type of amino protection has been mainly exploited in side-chain protection to allow for selective chemistry such as selective acylations, e.g. cyclizations, to be performed on protected peptides in solution or in the resin-bound state (see Section 4.3.2.3.4). An additional interesting application of the Aloe group is the one-pot deprotection and acylation with carboxy components resistant to the paUadium(0)-catalyzed allyl cleavage by hydrostannolysis as reported in Section 4.3.2.3.4.P 1... 

The natural abundance 15NNMR spectra of urea-formaldehyde and melamine-formaldehyde adducts and resins (recorded with approximately 20000 pulses) can be used for direct determination of different types of amino groups. The spectra of a urea-formaldehyde resin (1 1 formaldehyde/urea ratio) after 15 and 60 min of reaction are shown in Fig. 3. On the basis of chemical shifts of urea based model compounds (monomethylol-, Af,AT-dimethylol- and N,N,N -trimethylol-ureas) the following assignment of nine 15N resonances is proposed... 

This, in its very simplest form, is the chemistry of amino coatings. There are, of course, an enormous variety of types and reactivities of both amino compounds and polymers. While it would be useless to try to enumerate the variations possible, some systematization of the reactivity of amino resins is necessary to understand the trends in the coating industry. 

The global thermoset resins market is expected to reach as high as 95 million metric tons by 2016 (Axis Research Mind report 2012). Excluding the alkyd resins, which are used primarily in the coatings, commercially important major types of thermoset resins, altuig with their relative % market share, estimated from literature (Fosdyke and Starr 2002), can be categorized as follows Polyurethanes (31 %), PhenoUcs (18 %), Amino resins (18 %), Unsaturated polyesters (12 %), Epoxies and other specialty/high performance thermosets (12 %), such as silicones, polyimides, bismaleimides (BMl), cyanate ester thermosets, etc. 

The commonly used resins in the manufacture of decorative and industrial laminates ate thermosetting materials. Thermosets ate polymers that form cross-linked networks during processing. These three-dimensional molecules ate of essentially infinite size. Theoretically, the entire cured piece could be one giant molecule. The types of thermosets commonly used in laminates ate phenoHcs, amino resins (melamines), polyesters, and epoxies. 

Amino resins are manufactured throughout the industrialized world to provide a wide variety of useful products. Adhesives (qv), representing the largest single market, are used to make plywood, chipboard, and sawdust board. Other types are used to make laminated wood beams, parquet flooring, and for furniture assembly (see Wood-BASED composites and laminates). 

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