Synthetic binders phenolic resins

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. 

In a first classification, we can distinguish (i) boards made with an external synthetic binder, such as urea-formaldehyde or phenol-formaldehyde resins for thermosets, and (ii) boards with internal natural binders. The products cited below do not constitute an exhaustive list. 

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. 

Uses Mfg. of phenolic and thermosetting resins, furan polymers, urea-formaldehyde resins wetting agent foundry sand binders corrosion-resist, resins intermediate for esterification and etherification paints solvent, plasticizer for phenolic resins solvent for dyes and resins nonreactive epoxy resin diluent vise, reducer, cure promoter, and carrier in amine-cured epoxy resins gel retarder in casein/protein glues polymer sealants/cements synthetic flavoring agent in foods and pharmaceuticals cosmetics ingred. in food-pkg. adhesives... 

Phenolic resins are the oldest synthetic polymers. They were synthesised in the 19th century and their commercial value identified as early as 1905, with Bakelite. Traditional engineering uses for these thermosetting materials include moulding materials, grinding wheels, foundry binders and friction material binders. All these applications took advantage of the material s excellent heat and dimensional stability and adhesive qualities. 

Iditol. A synthetic resin obtained by the condensation of phenol formaldehyde. It is used as a binder in many Russian pyrotechnics Ref Gorst (1957), 162... 

Asbestos-reinforced organic binders (thermoplastics, duroplasts and elastomers) are widely utilized e.g. hardenable molding materials on the basis of asbestos-reinforced phenol or melamine resins for the manufacture of insulating components for combustion engines, components for electrical installations, cogwheels etc. Possible fiber substitutes are glass fibers, carbon fibers and other synthetic fibers (e.g. aramide fibers) and non-fiber fillers such as calcium carbonate, clay or talcum. 

The polymer concretes are distinguished by the nature of the binder e.g., furan, polyester, epoxy, phenol formaldehyde, carbamide, and so on. The classification of the main types of polymer concrete according to the kind of synthetic resins involved is shown in Figure 1.2 [7],... 

The first synthetic thermosets used as adhesives were phenol-formaldehyde resins produced at the end of the nineteenth eentury, historically linked to Baekeland s process which attained industrial status at the beginning of the twentieth century [4], Furanic condensates appeared mueh later as a result of the marketing of 2. They were first used as foundry binders by Quaker Oats in 1960. The use of furanic resins in the aerospace industry began ten years later. Although furanic resins represent a mere 1 % of the total thermoset produetion, the high added-value of these materials amply justifies their use. In fact, furan-based adhesives and binders are fire-, solvent-, and acid- or alkali-resistant. They are known, however, to display two main drawbacks related to their sensitivity to shrinkage and oxidation. 

Most amino and phenolic thermosets are used in the production of composites, mainly prepared with wood (wood-plastic composites, WPC) [68]. Particleboard, or the chipboard is a kind of WPC, which is produced from wood particles, such as wood chips or saw dusts, through their glueing together with synthetic resins or other suitable binders, by pressing and extruding afterwards. In most particleboards, the resin used is formaldehyde-based. 

The main natural resins used as wood panel binders are vegetal tannin adhesives, lignin adhesives and more recently also soy protein adhesives [1]. Of these, tannin-based adhesives have been used commercially the longest, since 1971. They offer the advantage over the other two types of not needing any reinforcement with an oil-derived synthetic resin [1]. Lignin [2-5] and soy binders [1, 6-8], however, still require between 20% and 40% of the total resin to be either phenol-formaldehyde or most often PMDI (polymeric isocyanate) to satisfy the requirements of relevant board standards. 

The first 50 years of the twentieth century were the decades of discovery. Significant changes were made in the vehicles, which are the liquid portions of the coatings composed of binder and thinner. Since the 1900s and the introduction of phenolic synthetic resin vehicles, coatings have been designed to increase production and meet performance requirements at lower costs. These developments were highlighted by the introduction of nitrocellulose lacquers for the automotive and furniture industries followed by the alkyds, epoxies, vinyls, polyesters, acrylics, and a host of other resins and finally the polyurethanes. 

The earliest preparation of CMS was based on the decomposition of a Saran co-polymer (90/10 mixture of vinylidene chloride and vinyl chloride) today CMS with a wide range of physical properties are made from a variety of natural and synthetic precursors. These include coal, coconut shell, phenol-formaldehyde resin, polyfurfuryl-alcohol, polyacrylonitrile, polyvinyl-alcohol, and cellulose, with coal tar pitch used in most cases as a binder [30-33],... 

---