Resols paints

Phenolic resins are useful surface coating materials. Resols are useful for stoving lacquers for coating chemical plant, textile equipment, razor blades, brassware cuid food cans. Phenolic resins are used with poly(vinyl formal) as a flexible, tough and solvent-resistant wire enamel. Oil-soluble resins based on synthetic phenols form the basis of some gloss paints. 

Resols suitable for use in paints generally cannot be used as the sole binder because they produce very hard, brittle paint films after stoving. They must therefore be combined with other paint raw materials [e.g., epoxy resins, poly(vinyl butyrals and polyester resins)]. 

BGVV Empfehlung XL for Germany. Depending on the raw material, most as-sup-plied resols contain relatively large amounts of toxic substances (phenols, formaldehyde, etc.). They must therefore be properly labelled, stored, and handled. As a result of improvements in production methods and the choice of suitable raw materials, useable resols with greatly reduced levels of toxic substance have been developed and made available to the paint industry. 

Combinations with Poly (Vinyl Butyrals). Poly(vinyl butyral) resins with a high acetal content are used, like epoxy resins, to plasticize resols. The weight ratio of resols to poly(vinyl butyral) is generally between 95 5 and 70 30. The employed application methods and curing conditions are similar to those used in the resol-epoxy resin systems. The resistance of such paint films to organic solvents, amines. 

Electrical Insulation Paints. Resols combined with poly(vinyl butyral), oil-free polyester resins, or poly(vinyl formal), as plasticizing components are used for this special application. The presence of small amounts of free phenols can increase the reactivity of these systems. These paints are used to coat wires, sheet metal for transformers and dynamos, as well as to impregnate electric motor windings. The paints are cross-linked at 100-300°C. 

Compared with phenolic resol resins, novolacs are of only minor importance as paint binders. Novolacs are, however, still very important as binders for basic dyes in printing inks. 

Modified phenolic resins are condensation products of the resol type which contain other starting materials besides phenol and formaldehyde (e.g., acrylic monomers). The phenolic component itself is often modified (alkyl- or arylphenols). Modification with rosin is the most important one. The compatibility of phenolic resins with other binders can be substantially improved by modification. Rosin-modified phenolic resins may be combined with linseed oils and alkyd resins. Examples of use include putties, priming coats, rust protection paints, and colored topcoats. 

Optical properties Mostly available in dark, opaque colours (novolaks), though transparent, unfilled castings are formed by reacting cresols or resourcinol with formaldehyde (resoles). May be painted or decorated by electroplating. 

D-Limone, 2% pet (paints, coatings) Pentachlorophenol (PCP), 1% aq (wood preservatives) Phenol-formaldehyde resin, 1% pet. Resol (resins, glues, plywood)... 

The liquid component of the adhesive (Liquid E) was a phenolic resole having a controlled phenol to formaldehyde ratio of 1 1.57 and a relatively high alkaline content. It was painted onto the substrate to be bonded and was then covered with polyvinyl acetal, a high-molecular-weight polymer in powder form. Figure 13.4 shows the chemical structure of the adhesive, and Fig. 13.5 illustrates the typical application process for Redux liquid and powder, which is still valid today. 

Phenolic resin is one of the common synthetic resins that have been used in a wide range of applications such as paints, adhesives, and composites. Phenolic resin is one of the thermoset class of polymers which has two types, namely resole type and novolac type, the formation of which depends on the synthetic method and catalyst used. Many attempts have been made to enhance the toughness and thermal properties of phenolic resin. By the fundamental concept of hybrid materials preparation, the sol-gel method can be utilized to incorporate inorganic components into the phenolic resin and improve its properties. These systems have been studied by Haraguchi et al. and Lin et al. ... 

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