Bonded abrasive phenolic

Bonded abrasives Phenolics Epoxy Alkyd Natural rubber SBR Shellac Polyimide Grinding wheel... 

Other applications for phenolics are switchgears, handles, and appliance parts, such as washing machine agitators (that s why they re usually black). Phenolics are widely used to bond plywood, particularly exterior and marine grades. Although urea-formaldehyde resins are cheaper for this purpose, they were not nearly as water-resistant and have been limited to interior grades. Abrasive wheels and brake linings also are bonded with phenolic adhesives. 

Bond Type. Most bonded abrasive products are produced with either a vi tie oils (glass or ceramic) or a resinoid (usually phenolic resin) bond. 

Modified Synthetic Adhesives. Phenol-formaldehyde (68) and urea-formaldehyde (69) are important synthetic adhesives. Phenol-formaldehyde adhesives (PF) find a variety of applications including bonded abrasives, foundry applications, fiber bonding, and wood bonding. Urea-formaldehyde adhesive resins (UF) are used generally to bond wood products. I will illustrate the modification of synthetic adhesives with carbohydrates using both these general types of adhesives. 

Although in 1909 Baekeland obtained patent coverage for the use of phenolics in bonding abrasives, it was not until 1921 that it became commercially useful. Phenolic bonded grinding wheels were found to be capable of being operated safely at higher speeds and with improved quality. 

Abrasives. Grinding wheels (bonded abrasives) and sandpaper (coated abrasives) are made from abrasive grit bonded by phenolic resin. The abrasive grit may be alumina for cutting and polishing steel, or silicon carbide for handling glass, ceramics, and stone. This uses 1 percent of the phenolic resin market. 

Furfural has been used to extract color bodies from crude wood rosins. One of the earliest uses of furfural was as a solvent and processing aid for coal and coal products. Furfural has been used as a reactive solvent with pulverized phenolic resin in the manufacture of resin-bonded abrasive grinding wheels. The furfural serves as a plasticizer and wetting agent in the resin mix which is cold molded and cured during a baking cycle. Furfural becomes a reacted component in the final resin structure. 

Abrasives are hard, inert particles such as silicon carbide and aluminum oxide used for cutting, shaping, polishing, or cleaning. The adhesive functions as a binder in the manufacture of bonded and coated abrasives. A bonded abrasive such as a grinding wheel is a molded mixture of abrasive particles and binders. In a coated abrasive, e.g., sandpaper or emery paper, a particle layer is glued to a flexible backing. The predominant binder is phenolic resin (Table 30). 

Nitrile rubber/phenolic adhesives are also quite useful in adhering rubber to various met-als, " e.g., in the manufacture of rubber covered metal rollers. Huber reported that a nitrile/phenolic adhesive composition provided excellent bonding of rubber to a magnesium roll (Table 20). Other metal bonding applications with nitrile rubber/phenolic adhesives include laminating aluminum foil to paper and then to wood, bonding abrasives to metal, and bonding polyamide to metal. 

Phenolics are used in two main categories of abrasives. Bonded abrasives are three-dimensional structures such as grinding wheels and snagging wheels, and coated abrasives include sandpaper, sanding discs, and belts. According to the data reported in Table 1, the markets for abrasives have decreased by 11 million lb during the years from 1983 to 1987. 

Although the ceramic binders in bonded abrasives are generally harder and can be used in close tolerance work, the phenolic binders are tougher and can better withstand thermal and mechanical shock. The two main abrasives that are used in grinding wheels are aluminum oxide and silicon carbide. However, titanium oxide can be added to aluminum oxide for toughness enhancement, and an alloy of zirconium oxide and aluminum oxide developed by the Norton Company is important in heavy... 

Modem civilization would not be possible without bonded abrasive products. By the year 1825 sand, emeiy, and even diamond were being bonded together with shellac for use in abrasive sticks and wheels. Rubber bonded wheels were introduced in 1857, the sodium silicate and the vitrified bond just after the Civil War, and the phenolic resin bond in 1923. The metal bond was introduced for diamond wheels in 1940. 

NBR adhesives have excellent shelf stability and high temperature properties. They are used in aircraft, automobile, paper, and electronics applications. Blended with phenolic resins, they have been used to laminate aluminum and stainless steel, fabricate airplane structures, bond abrasives to metal, brake linings to brake shoes, laminate leather, attach soles in shoe manufacturing and bond cardboard, polymeric films, masonite, wood and metal to each other and themselves. Nitrile rubber-phenohc resin blends are poor adhesives for non polar elastomers such as natural rubber, butyl rubber, polyethylene unless their surfaces have been activated to improve adhesion. 

Useful thermosetting resins are obtained by interaction of furfural with phenol. The reaction occurs under both acidic and basic catalysis. Other large uses of furfural together with phenol are in the manufacture of resin-bonded grinding wheels and coated abrasives (5). 

Phenol-formaldehyde resins find numerous applications in such areas as wood composites, fiber bonding, laminates, foundry resins, abrasives, friction and molding materials, coatings and adhesives, and flame retardants (JL). From a specialty chemicals standpoint, they are also used as developer resins in carbonless papers (2.). Conventional methods of preparation involve condensation of a phenol with formaldehyde under either acidic (novolak) or basic (resole) conditions (2). Their typical molecular weight range is from 800-4000 daltons (D) and includes a wide variety of alkyl or aryl substituted phenols (A)- The... 

Pantoxyl(8>. [Qmdea Chemie GmbH] Phenolic and melamine resins bonding resins for wood processing, abrasives, foundry industiy. 

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