Phenol formaldehyde manufacture

Some commercially important cross-linked polymers go virtually without names. These are heavily and randomly cross-linked polymers which are insoluble and infusible and therefore widely used in the manufacture of such molded items as automobile and household appliance parts. These materials are called resins and, at best, are named by specifying the monomers which go into their production. Often even this information is sketchy. Examples of this situation are provided by phenol-formaldehyde and urea-formaldehyde resins, for which typical structures are given by structures [IV] and [V], respectively ... 

Amino and Phenolic Resins. The largest use of formaldehyde is in the manufacture of urea—formaldehyde, phenol—formaldehyde, and melamine—formaldehyde resins, accounting for over one-half (51%) of the total demand (115). These resins find use as adhesives for binding wood products that comprise particle board, fiber board, and plywood. Plywood is the largest market for phenol—formaldehyde resins particle board is the largest for urea—formaldehyde resins. Under certain conditions, urea—formaldehyde resins may release formaldehyde that has been alleged to create health or environmental problems (see Amino RESINS AND PLASTICS). 

At one time urea-formaldehyde was used extensively in the manufacture of plywood but the product is today less important than heretofore. For this purpose a resin (typically U-F molar ratio 1 1.8)-hardener mixture is coated on to wood veneers which are plied together and pressed at 95-110°C under pressure at 200-800 Ibf/in (1.38-5.52 MPa). U-F resin-bonded plywood is suitable for indoor application but is generally unsuitable for outdoor work where phenol-formaldehyde, resorcinol-fonnaldehyde or melamine modified resins are more suitable. 

By far the preponderance of the 3400 kt of current worldwide phenolic resin production is in the form of phenol-formaldehyde (PF) reaction products. Phenol and formaldehyde are currently two of the most available monomers on earth. About 6000 kt of phenol and 10,000 kt of formaldehyde (100% basis) were produced in 1998 [55,56]. The organic raw materials for synthesis of phenol and formaldehyde are cumene (derived from benzene and propylene) and methanol, respectively. These materials are, in turn, obtained from petroleum and natural gas at relatively low cost ([57], pp. 10-26 [58], pp. 1-30). Cost is one of the most important advantages of phenolics in most applications. It is critical to the acceptance of phenolics for wood panel manufacture. With the exception of urea-formaldehyde resins, PF resins are the lowest cost thermosetting resins available. In addition to its synthesis from low cost monomers, phenolic resin costs are often further reduced by extension with fillers such as clays, chalk, rags, wood flours, nutshell flours, grain flours, starches, lignins, tannins, and various other low eost materials. Often these fillers and extenders improve the performance of the phenolic for a particular use while reducing cost. 

While discussing ethers we should mention that the presence of unreacted anisoles or methyl anisoles is highly undesirable in the manufacture of phenol-formaldehyde resoles. These materials tend to be unreactive relative to phenol under normal resole conditions. They are also volatile and have odors detectable at very low concentrations. They have been the source of worker complaints and costly claims in the wood products industry. Benzophenones and methyl phenyl ketones are also common phenol contaminants that are problematic in this regard. 

A reaction vessel explosion at BASF s resins plant in Cincinnati (July 19, 1990) killed one and injured 71. The BASF facility manufactures acrylic, alkyd, epoxy, and phenol-formaldehyde resins used as can and paper-cup liner coatings. The explosion occurred when a flammable solvent used to clean a reaction vessel vented into the plant and ignited. The cleaning solvent that was not properly vented to a condenser and separator, blew a pressure seal, and fdled the 80-year-old building with a white vapor cloud. 

Formaldehyde is prepared industrially (for the manufacture of phenol-formaldehyde resins) by the catalytic oxidation of methanol ... 

Phenol-formaldehyde (PF) resins were synthesized to manufacture non-flammable insulating foam. When alkali catalyst, for example, barium hydroxide (Ba(OH)2), was present, lesol resins are produced[l]. In the analj s of molecular species of resol, capillary GC-MS had been used to separate hemiformal-type compoimds(acetylated hydroxybenzylhaniformals)... 

The major disadvantage associated with urea-formaldehyde adhesives as compared with the other thermosetting wood adhesives, such as phenol-formaldehyde and polymeric diisocyanates, is their lack of resistance to moist conditions, especially in combination with heat. These conditions lead to a reversal of the bond-forming reactions and the release of formaldehyde, so these resins are usually used for the manufacture of products intended for interior use only. However, even when used for interior purposes, the slow release of formaldehyde (a suspected carcinogen) from products bonded with urea-formaldehyde adhesives is observed. 

EICEIO, a gas with an irritating smell. It is made industrially by the oxidation of methyl alcohol, and is used in the manufacture of phenol-formaldehyde and urea-formaldehyde resins and plastics. 

In general, the acid-sorbing resins may be classified as high molecular weight polyamines or polyimines. Thus, the original Adams and Holmes material was a polymer of m-phenylenediamine. Cation Exchange materials include synthetic resins, such as sulfonated phenol-formaldehyde or polystyrene types, and sulfonated coal. Some manufacturers have a variety of sub-types which are considered superior for particular applications. 

Similar to the findings of Kauppinen et al. (1986), a large (14,861) cohort mortality study of workers in the phenol-formaldehyde resin manufacturing industry found nondose-related increases in the risk of... 

The polymerization of phenols or aromatic amines is applied in resin manufacture and the removal of phenols from waste water. Polymers produced by HRP-catalyzed coupling of phenols in non-aqueous media are potential substitutes for phenol-formaldehyde resins [123,124], and the polymerized aromatic amines find applications as conductive polymers [112]. Phenols and their resins are pollutants in aqueous effluents derived from coal conversion, paper-making, production of semiconductor chips, and the manufacture of resins and plastics. Their transformation by peroxidase and hydrogen peroxide constitutes a convenient, mild and environmentally acceptable detoxification process [125-127]. 

Uses Preparation of sodium and butyl benzoates, benzoyl chloride, phenol, caprolactum, and esters for perfume and flavor industry plasticizers manufacture of alkyl resins preservative for food, fats, and fatty oils seasoning tobacco dentifrices standard in analytical chemistry antifungal agent synthetic resins and coatings pharmaceutical and cosmetic preparations plasticizer manufacturing (to modify resins such as polyvinyl chloride, polyvinyl acetate, phenol-formaldehyde). 

Table 12.3 summarizes the uses of formaldehyde. Two important thermosetting plastics, urea- and phenol-copolymers, take nearly one half the formaldehyde manufactured. Urea-formaldehyde resins are used in particleboard, phenol-formaldehyde resins in plywood. 1,4-Butanediol is made for some polyesters and is an example of acetylene chemistry that has not yet been replaced. Tetrahydrofiiran (THF) is a common solvent that is made by dehydration of 1,4-butanediol. 

Hexamethylenetetramine (HMTA) has important uses in modifying phenolic resin manufacture and is an intermediate in explosive manufacture. Although it is a complex three-dimensional structure, it is easily made by the condensation of formaldehyde and ammonia. 

Trade (and/or brand) names and abbreviations are often used to describe a particular material or a group of materials. They may be used to identify the product of a manufacturer, processor, or fabricator, and may be associated with a particular product or with a material or modified material, or a material grouping. Trade names are used to describe specific groups of materials that are produced by a specific company or under license of that company. Bakelite is the trade name given for the phenol-formaldehyde condensation developed by Baekeland. A sweater whose material is described as containing Orion contains polyacrylonitrile fibers that are protected under the Orion trademark and produced or licensed to be produced by the holder of the Orion trademark. Carina, Cobex, Dacovin,... 

Volatile organic chemicals are released during a number of industrial and manufacturing operations. For example, 1,3-butadiene is an important raw material in the manufacture of synthetic rubber During manufacture small amounts of the chemical escape into the air. Formaldehyde is a raw material used in the manufacture of a variety of building materials, such as phenol-formaldehyde and melamine resins. Many household products, such as cleaning products, varnishes, waxes, paints, and organic solvents, contain VOCs, which vaporize and escape easily into the atmosphere when they are used. For this reason, VOCs often build up indoors. 

As aqueous solution, it is used as a parent compound for preparation of numerous chemicals used in industry, such.as in the manufacture of explosives, plastics, resins (eg phenol-formaldehyde resins) etc (See... 

Recent work has concentrated on the use of ALCELL lignin as a substitute for phenol-formaldehyde resins in wood adhesives, particularly wafer-board. Some of the results obtained when a PF resin (Bakelite 9111) was replaced with different levels of hardwood ALCELL lignin in waferboard manufacture will be briefly discussed below. Table III shows the conditions used for waferboard manufacture. 

In the April, 1975, issue of Plywood Panel magazine, we find reported square feet, quarter inch basis, domestic hardwood plywood manufactured in this country was approximately 3.5 billion and softwood plywood was 27.5 billion. This means 89 percent of the total plywood produced was softwood plywood, and 97 percent of this production was glued with phenol-formaldehyde resin adhesives, according to the American Plywood Association. This leaves 11 percent domestic hardwood plywood which was 95 percent glued with urea-formaldehyde resin adhesives,... 

In 1973, over 500 million solid pounds of phenol-formaldehyde resin were used in the manufacture of softwood plywood in the U. S. A. About 60 million solid pounds of urea-melamine-formaldehyde resin were consumed in the hardwood plywood industry. 

Phenolic resins for plywood are typically caustic-catalyzed phenol-formaldehyde resoles. Typical resins are water solutions containing 40-44 percent resin solids composed of 23 - 25 percent phenol, 5-7 percent sodium hydroxide and 10 - 12 percent formaldehyde. The ratio of formaldehyde to phenol in a resin has a decided effect on performance characteristics as does the synthesis procedure used in manufacturing the resin. 

Hexamethylenediamine is used in the production of nylon 6,6 and mainly in making phenol-formaldehyde resins, where it is known as hexa. It is also used as a urinary antiseptic (Urotropine) as well as in the rubber industry and for the manufacture of the explosive cyclonite. 

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. 

Probably the most widely used of these is glassy carbon, which is isotropic. However, due to its hardness and fragility, electrode fabrication is difficult, which essentially limits its use to the dimensions and forms that can be acquired commercially. The manufacture of glassy carbon consists in carbonization by heating phenol/formaldehyde polymers or polyacrylonitrile between 1000°C and 3000°C under pressure. Since glassy carbon has some amorphous characteristics, as can be seen from Fig. 7.1, it is not always homogeneous. 

The phenol derivatives figure in the structures of a number of important reactions, including the synthesis of aspirin and the manufacture of phenol - formaldehyde plastics and glues. 

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