Combination with synthetic resins

Finally, it should be stated that the processes that use lignin alone as thermosetting resin in particleboards 4-6) did not find industrial application, whereas, the processes using lignin in combination with synthetic resins 2,7) are economically feasible though the remaining proportion of synthetic resin is still relatively high (60%). 

CNC SOFT C-2-U is a synthetic softener for use on fabrics of all constructions where a soft, smooth, silky hand is desired. It is a fine all-purpose fiber lubricant and softener and is particularly recommended for use in combination with thermosetting resins and cross-linking agents to produce a smooth hand and also to minimize tearing and tensile strength loss and improve resistance to abrasion. 

Other earlier applications of nitrated starch included propellants,1468 nitrogen fertilizers used together with ammonium salts,1469 a component of ignition preparations,1470 and a lacquer component.1471-1473 It has been used as a lacquer component because of its resinous properties, its ability to combine physically with synthetic resins,1474 and also because of its solubility in alcohols and aromatic hydrocarbons. 

The main parameter for the application of tannins as adhesives for wood-based panels is the content of reactive polyphenols and the reactivity of these components towards formaldehyde. Tannins can be used as adhesives alone (with a formaldehyde component as crosslinker) or in combination with aminoplastic or phenolic resins. These resins can react chemically with the tannin component in a polycondensation reaction, form only two interpenetrating networks, or both. The simplest adhesive mix formulation consists of the tannin solution and powdered paraformaldehyde as crosslinker [283]. The addition of paraformaldehyde can cause in the short term a relatively high level of formaldehyde emission. Glue mixes using paraformaldehyde for the production of particleboards with low formaldehyde emission are described and used industrially [284]. In the literature a large number of papers describe the combinations of tannins with synthetic resins (Table 14). 

Furthermore, drying oils can be combined with all kinds of other substances the results obtained with synthetic resins are of extreme importance for varnish industry. 

Solvents are sometimes needed to reduce the viscosity of the adhesive to enhance its spreadability. Solvents used with synthetic resins and elastomers are generally organic in nature. Often a mixture of solvents is needed to achieve the desired processability characteristics such as controlled solvent evaporation and removal. This can be accomplished by combining solvents with variable volatilities. 

Ethyl cellulose cellulose nitrate in solution (or general-purpose household cement), epoxy, nitrile-phenolic, synthetic rubber or thermoplastic resin combined with thermosetting resin, and resorcinol-formaldehyde. 

In addition, they are used in combination with casein solutions and synthetic resin emulsions. Whereas starch ethers and esters and also aldehyde starches are used to only a limited extent in the adhesives field, the thermal degradation products of starches, the water-soluble dextrins, are still important in quantitative terms as raw materials for adhesives. They are used on their own in aqueous form or as mixtures with synthetic resin emulsions. 

Mixed Glues. Starches and dextrins also are used in combination with other raw materials in adhesives. For example, the resistance to water of starch-based adhesives can be improved by the addition of melamine-formaldehyde or urea-formaldehyde resins. Mixtures of starch-based adhesives or dextrin-based adhesives with synthetic resin dispersions are also used. 

Oils (Martens, 1974) are used in coatings either by themselves, as a portion of the nonvolatile vehicle, or as an integral part of a varnish when combined with resin, or of a synthetic liquid when combined with its resinous portion. Table 3.2 lists oils used in the coatings industry in 1977. In particular, oil... 

Synthetic resins, such as phenoHc and cresyUc resins (see Phenolic resins), are the most commonly used friction material binders, and are usually modified with drying oils, elastomer, cardanol [37330-39-5] an epoxy, phosphoms- or boron-based compounds, or even combinations of two. They ate prepared by the addition of the appropriate phenol and formaldehyde [50-00-0] in the presence of an acidic or basic catalyst. Polymerization takes place at elevated temperatures. Other resin systems are based on elastomers (see Elastomers, synthetic), drying oils, or combinations of the above or other polymers. 

The technical uses of phenol are important, particularly in the manufacture of salicylic add (Chap. VI. 4, p. 249), and in that of the valuable synthetic resins of the bakelite type (condensation with formaldehyde). Under mild conditions phenol may be caused to combine with formaldehyde giving p-hydroxybenzyl alcohol ... 

The most familiar negative photoresists are examples of two-component, resist materials. These include Kodak s KTFR, Merck s Selectilux N, Hunt s HNR, etc., all of which consist of a cyclized synthetic rubber matrix resin which is radiation insensitive but forms excellent films. This resin is combined with a bis-arylazide sensitizer. 

Another use of urea is for resins, which are used in numerous applications including plastics, adhesives, moldings, laminates, plywood, particleboard, textiles, and coatings. Resins are organic liquid substances exuded from plants that harden on exposure to air. The term now includes numerous synthetically produced resins. Urea resins are thermosetting, which means they harden when heated, often with the aid of a catalyst. The polymerization of urea and formaldehyde produces urea-formaldehyde resins, which is the second most abundant use of urea. Urea is dehydrated to melamine, which, when combined with formaldehyde, produces melamine-formaldehyde resins (Figure 96.2). Melamine resins tend to be harder and more heat-resistant than urea-formaldehyde resins. Melamine received widespread attention as the primary pet food and animal feed contaminant causing numerous cat and dog deaths in early... 

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