Polymers phenolic resins

E.I. Du Pont de Nemours, Colloidal stable solvent cement compositions comprising chloro-prene polymers, phenolic resins and polyisocyanate, U.S. Patent 3,318,834, 9 May, 1967. 

Phenol is used in the manufacture of formaldehyde resins, bisphenol A, caprolactam, aniline, xylenols, and alkylphenols. Phenol-formaldehyde polymers (phenolic resins) have a primary use as the adhesive in plywood formulations. The use of phenol in detergent synthesis to make alkylphenols is an important aspect of phenol utility. 

Indirect food additives Polymers —phenolic resins in molded articles FDA 2000c 21CFR177.2410 (b)... 

Phenol itself was formerly known as carbolic acid. It forms colorless needles (m.p. 41°C), has a characteristic odor, and is somewhat soluble in water. Aqueous solutions of it (or its methyl-substituted derivatives) are applied as disinfectants, but its main use is for the preparation of polymers (phenolic resins Section 22-6). Pure phenol causes severe skin bums and is toxic deaths have been reported from the ingestion of as little as 1 g. Fatal poisoning may also result from absorption through the skin. 

Phenolic Resins. At elevated temperatures, phenoHc resins are cured with polysulfide resins through a condensation reaction. The product may be considered a block copolymer of the rigid phenoHc resin and the flexible polysulfide. Thus, the polysulfide acts to flexibiHze the resulting polymer. 

Amino resins are thermosetting polymers made by combining an aldehyde with a compound containing an amino (—NH2) group. Urea—formaldehyde (U/F) accounts for over 80% of amino resins melamine—formaldehyde accounts for most of the rest. Other aldehydes and other amino compounds are used to a very minor extent. The first commercially important amino resin appeared about 1930, or some 20 years after the introduction of phenol—formaldehyde resins and plastics (see Phenolic resins). 

Polymers. Quinoline and its derivatives may be added to or incorporated in polymers to introduce ion-exchange properties (see Ion exchange). For example, phenol—formaldehyde polymers have been treated with quinoline, quinaldine, or lepidine (81) (see Phenolic resins). Resins with variable basic exchange capacities have been prepared by treating Amherlites with 2-methylquinoline (82). 

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 thermoplastic or thermoset nature of the resin in the colorant—resin matrix is also important. For thermoplastics, the polymerisation reaction is completed, the materials are processed at or close to their melting points, and scrap may be reground and remolded, eg, polyethylene, propjiene, poly(vinyl chloride), acetal resins (qv), acryhcs, ABS, nylons, ceUulosics, and polystyrene (see Olefin polymers Vinyl polymers Acrylic ester polymers Polyamides Cellulose ESTERS Styrene polymers). In the case of thermoset resins, the chemical reaction is only partially complete when the colorants are added and is concluded when the resin is molded. The result is a nonmeltable cross-linked resin that caimot be reworked, eg, epoxy resins (qv), urea—formaldehyde, melamine—formaldehyde, phenoHcs, and thermoset polyesters (qv) (see Amino resins and plastics Phenolic resins). 

Commonly accepted practice restricts the term to plastics that serve engineering purposes and can be processed and reprocessed by injection and extmsion methods. This excludes the so-called specialty plastics, eg, fluorocarbon polymers and infusible film products such as Kapton and Updex polyimide film, and thermosets including phenoHcs, epoxies, urea—formaldehydes, and sdicones, some of which have been termed engineering plastics by other authors (4) (see Elastol rs, synthetic-fluorocarbon elastol rs Eluorine compounds, organic-tdtrafluoroethylenecopolyt rs with ethylene Phenolic resins Epoxy resins Amino resins and plastics). 

One possible solution to the problem is to make greater use of intumescent materials which when heated swell up and screen the combustible material from fire and oxygen. Another approach is to try to develop polymers like the phenolic resins that on burning yield a hard ablative char which also functions by shielding the underlying combustible material. 

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. 

Because of a small dipole polarisation effect the dielectric constant is somewhat higher than that for PTFE and the polyolefins but lower than those of polar polymers such as the phenolic resins. The dielectric constant is almost... 

In recent years there have been comparatively few developments in phenolic resin technology apart from the so-called Friedel-Crafts polymers introduced in the 1960s and the polybenzoxazines announced in 1998 which are discussed briefly at the end of the chapter. 

For many years there has been a demand for rigid plastics materials which could withstand temperatures of 250°C and at the same time have good oxidation and water resistance coupled with ease of processability and reasonable cost. Such a demand led in the late 1960s to the small-scale production of a number of polymers which could be considered as being intermediate between polyphenylene, Figure 23.24, and the commercial phenolic resins. 

The commercial appearance of phenolic resins fibres in 1969 is, at first consideration, one of the more unlikelier developments in polymer technology. By their very nature the phenolic resins are amorphous whilst the capability of crystallisation is commonly taken as a prerequisite of an organic polymer. Crystallisability is not, however, essential with all fibres. Glass fibre, carbon fibre and even polyacrylonitrile fibres do not show conventional crystallinity. Strength is obtained via other mechanisms. In the case of phenolic resins it is obtained by cross-linking. 

Amongst the important heat-resisting cross-linked polymers are the phenolic resins (chapter 23), the Friedel-Crafts resins (also Chapter 23), the polyphenylenes (Chapter 21) and certain polysulphides (also Chapter 21). One problem of these materials is that they tend to be brittle. This is overcome in part... 

Lin, R. Y. and Economy, J., Preparation and properties of activated carbon fibers derived from phenolic resin precursor, Appl. Polym. Symp., 1973, 21, 143 152. 

Thousands of technical papers and many books have been written on the subject of phenolic resins. The polymer is used in hundreds of diverse applications and in very large volumes. It is used worldwide. In fact the term phenolic resin encompasses a wide variety of materials based on a broad range of phenols and co-monomers. In this short article, we cannot expect complete coverage. Our hope is that we can provide an understanding of the fundamental chemistries, uses, and values of these materials as well as enough references to permit the interested reader to begin his own exploration of the topic. 

The PVF is made by acidic reaction between poly(vinyl alcohol) (PVA) and formaldehyde. The poly(vinyl alcohol) is, in turn, made by hydrolysis of poly(vinyl acetate) or transesterification of poly(vinyl acetate). Thus, residual alcohol and ester functionality is usually present. Cure reportedly occurs through reaction of phenolic polymer hydroxyls with the residual hydroxyls of the PVA [199]. The ester residues are observed to reduce bond strength in PVF-based systems [199]. This does not necessarily extend to PVF-P adhesives. PVF is stable in strong alkali, so participation of the acetals in curing is probably unimportant in most situations involving resoles. PVF is physically compatible with many phenolic resins. 

Standard-grade PSAs are usually made from styrene-butadiene rubber (SBR), natural rubber, or blends thereof in solution. In addition to rubbers, polyacrylates, polymethylacrylates, polyfvinyl ethers), polychloroprene, and polyisobutenes are often components of the system ([198], pp. 25-39). These are often modified with phenolic resins, or resins based on rosin esters, coumarones, or hydrocarbons. Phenolic resins improve temperature resistance, solvent resistance, and cohesive strength of PSA ([196], pp. 276-278). Antioxidants and tackifiers are also essential components. Sometimes the tackifier will be a lower molecular weight component of the high polymer system. The phenolic resins may be standard resoles, alkyl phenolics, or terpene-phenolic systems ([198], pp. 25-39 and 80-81). Pressure-sensitive dispersions are normally comprised of special acrylic ester copolymers with resin modifiers. The high polymer base used determines adhesive and cohesive properties of the PSA. 

Carswell. T.S., Phenoplasts their structure, properties, and chemical technology. In Mark. H. and Melville, H.W. (Eds.), High Polymers. Interscience, New York, 1947, Chapter 1. Knop, A. and Pilato, L.A., Phenolic Resins. Springer-Verlag, Berlin, 1985, p. 3. 

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