Phenolic Resins for Coatings

Phenolic resins (i.e., condensation products of phenols and formaldehyde) are among the oldest synthetic binders, and their first use in paint technology dates back to the early 1920s. Their primary uses have constantly changed since then, and new classes of synthetic binders have become increasingly important. 

Initially, phenolic resins attracted a great deal of interest because they appeared to be the first synthetic products that could be used as a substitute for natural resins (rosin, copal resins, shellac). Nowadays attention is mainly focused on performance and technical-economic competition between the widely differing groups of resins. 

The main disadvantage of phenolic resins is their intrinsic yellow to brown color. As a result they cannot be used for colored and white paints. They can only be used for decorative coatings in a few cases (e.g., gold lacquers). Phenolic resins have favourable mechanical properties and a high chemical resistance. Paint systems that are optimally adjusted to the requirement profile can be developed by suitable formulations. 

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Alnovol. [Hoechst Celanese/Fine Cbent] Phenolic resins for coatings, inks, rubber industry. 

Uses Adhesive polymer or in blends with phenolic resins for coatings Features Crumb form of Nipol 1001 LG Properties 41%ACN Nipol 1432T [Zeon Zeon Europe]... 

Bisphenol-A (BPA) or 2,2-i>/5(4-hydroxyphenyl) propane is used to produce special phenolic resins for coating applications, but the main use of bisphenol-A is in the production of polycarbonates and epoxide resins (Knop and Pilato, 1985). 

The growing interest in the BPA applications started in the late 1930s in connection with the start of fabrication and use of phenolic resins, especially modified oil-soluble phenolic resin for coating applications, as well as antioxidants for rubber, plastic and oil products [10,11]. 

Richardson, S. H., Wertz, W. J., Phenolic Resins for Coatings, in Treatise on Coatings, Vol. 1, Part III, Meyers and Long, eds.. New York, Marcel Dekker, 1972, Chapter 3. 

The main application of poly (vinyl formal) is as a wire enamel in conjunction with a phenolic resin. For this purpose, polymers with low hydroxyl (5-6%) and acetate (9.5-13%) content are used. Similar grades are used in structural adhesive (e.g. Redux) which are also used in conjunction with phenolic resin. Poly(vinyl formal) finds some use as a can coating and with wash primers. Injection mouldings have no commercial significance since they have no features justifying their use at current commercial prices. 

Phenolic novolacs, 18 760-761 Phenolic resin adhesives, 18 783-784 Phenolic resin can coatings, 18 38 Phenolic resin composites, 18 792-794 Phenolic resin drying-oil varnishes, 18 783 Phenolic resin fibers, 18 797-798 mechanical properties of, 18 798 Phenolic resin foam, 18 795-796 Phenolic resin manufacturers, U.S., 18 774 Phenolic resin polymerization, 18 760-765 alkaline catalysts in, 18 762-765 neutral catalysts in, 18 761-762 strong-acid catalysts in, 18 760-761 Phenolic resin prepregs, 18 793 Phenolic resin production unit, 18 766 Phenolic resins, 10 409 18 754-755, 756-802 22 10 26 763 in abrasive materials, 18 786-787 in air and oil filters, 18 790 additional reactants in, 18 759 analytical methods for, 18 774-779 applications of, 18 781-798 batch processes for, 18 766 from biomass and biochemical processes, 18 769-770... 

The substituted phenols and cresols constitute about half the total volume of this group. Para-t-butylphenol is produced by the alkylation of phenol with isobutylene. The principal applications for this derivative are in the manufacture of modified phenolic resins for the rubber industry and in surface coatings. BHT is obtained from isobutylene and p-cresol. Technical-grade BHT is an antioxidant for plastics and elastomers, and is a gum inhibitor in gasoline. Food-grade BHT is an antioxidant in edible oils, preserves, and many other foods. 2,6-Di-t-butylphenol is used to produce a wide range of plastics additives, antioxidants, and gasoline additives. 

BiEDERMANN, M. and GROB, K., Submitted, Phenolic resins for can coatings I. Phenol-based resole analysed by GC-MS, GC X GC, NPLC-GC, SEC, FWF Food Science and Technology. 

Several higher homologs of phenol such as p-tertiary butyl phenol, p-tertiary amyl phenol and p-tertiary octyl-phenol are used to make oil-soluble phenolic resins for varnishes and other coatings systems. What structural features of these compounds make oil solubility of the resins possible ... 

It was not until the commercialization of synthetic plastics resins in the 1930s that an almost unlimited variety of base materials became available for compounding into adhesives and sealants. Most of the thermoplastic resins were soluble in organic solvents and were used as solvent adhesives for molded plastic articles of the same base composition and sometimes for other materials. Poly(vinyl chloride) (PVC), a thermoplastic developed in 1927, is used today in solvent formulations to bond PVC articles such as coated fabrics, films, foams, and pipe. In the early 1930s, phenolics came into importance as adhesive resins. Before that time they were used as coating varnishes [9, p. 239). About 1931 development of the use of a new phenolic resin for plywoods and veneers began [9, p. 239]. 

Uses Flame retardant, plasticizer for phenolic resins, paper coatings, PVC and PVC foams, acrylic, cellulosics, epoxy, phenolic, and PVAc polymers... 

Wood Paper Cellulosic separators are made from cotton linters or craft pulp and generally coated with phenolic resin for acid resistance and strength Comparatively large pore size and relatively high electrical resistance... 

There are six isomeric xylenols (dimethylphenols) (II). At one time, mixtures of the isomers were obtained from coal tar and petroleum refining streams but now xylenols are obtained mainly by the alkylation of phenol with methanol (see, for example, section 12.6.1). For the preparation of resins, 3,5-xylenol is the preferred isomer because it has three reactive positions. Xylenols are used for making oil-soluble phenolic resins for surface coatings. They are also used for making alkali-resistant grades of resins for moulding powders and laminates. 

Silicone resins for coatings resemble some phenol-formaldehyde polymers in that polymerization takes place in two stages. A trifunctional monomer such as phenyl-trichlorosilane may be hydrolyzed to the relatively stable hexamer (and related structures modified by comonomers for better solubility). 

Phenolic Dispersions. These systems are predominantly resin-in-water systems in which the resin exists as discrete particles. Particle size ranges from 0.1 to 2 p.m for stable dispersions and up to 100 p.m for dispersions requiring constant agitation. Some of the earliest nonaqueous dispersions were developed for coatings appHcations. These systems consist of an oil-modified phenoHc resin complexed with a metal oxide and a weak solvent. 

The resins should dry quickly and cure weU at low temperatures. They usually are made at a high pH with high ratios of formaldehyde to phenol and held to fairly low molecular weight. Typical viscosities are 15, 000 mPa-s(=cP) at 75% soHds content for a first coat and 1000 mPa-s(=cP) at 50% soHds for the top resin. For dense backing materials, such as fiber disks, a typical resin has a viscosity of 50, 000 mPa-s(=cP) at 80% soHds and is cured at 148°C. 

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. 

Epoxy phenolic coatings These materials are also cured at relatively high temperatures and are made by the reaction of the epoxy resin with the phenolic resin. They are slightly less critical in application requirements, are less sensitive to curing conditions and can be applied in thicker coats. The best use for both these materials is as tank linings used for the storage or food products, drinks, etc. or for process plant, evaporators, etc. that contain boiling water. 

It is not economical to use expensive woven material for long lines, which can be, and normally are, coated by mechanical means. For such lines the most commonly used material nowadays is a glass-fibre tissue of a nominal 0-5 mm thickness, consisting of glass fibres bonded together with a phenolic resin or starch. 

Substituted phenols such as cresols, p-fcrf-butylphenol, / -phcnylphenol, resorcinol, and cardanol (derived from cashew nut shells) have also been used as precursors for phenolic resins. Alkylphenols with at least three carbons in the substituent lead to more hydrophobic phenolic resins that are compatible with many oils, natural resins, and rubbers.7 Such alkylphenolic resins are used as modifying and crosslinking agents for oil varnishes, as coatings and printing inks, and as antioxidants and stabilizers. Bisphenol-A (2,2-p-hydroxyphenylpropane),... 

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