Foundry binders

In some resole appHcations, such as foam and foundry binders, a rapid cure of a Hquid resin is obtained at RT with strong acid. The reactions proceed in the same manner as those of novolak resin formation. Methylol groups react at ortho and para phenoHc hydrogen to give diphenyknethane units (41). 

Foundry binders Wood binders Rigid, 2-K structural adhesives... 

Phenolic resins are adaptable to many applieations. The list is very long, however, the major uses are wood binders, glass insulation binders, molding compounds, laminates, foundry binders, coatings, friction linings, abrasives, and oil well propants [59-66]. They have found their way into a number of new, high technology uses such as rocket motor wear parts, military armor, sports equipment. 

Though the discussion above was aimed primarily at wood binders, many of the ideas carry over into foundry and glass binding applications. For example, potassium hydroxide is used extensively in foundry binders as are esters and... 

FormolSS. [BASF AG] Urea-formaldehyde precondensate intermediate for nifg. adhesives and foundry binders. 

Green Bond . [Ashland/Foundry Prods.] Bentonite foundry binders. 

Unicast [Unicast Development] Foundry binders and chemicals. 

Above a certain concentration which decreases with increasing silica-soda ratio as explained above, sodium silicate aqueous solutions become very viscous and are stable for only a limited period of time. Stability in this case means resistance to gelling. More stable solutions can be made at lower sodium silicate concentrations but this may become impractical in a foundry binder. The high water content of very high ratio (more than 4 to 5) sodium silicate solutions at practical viscosities prevent their extended use as a foundry binder in the present invention. Excessively high water content in a foundry binder means unacceptably weak sand molds or cores and detrimental quantities of steam evolving when the molten metal is poured into the sand mold-core assembly. 

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. 

Furan resins have been extensively used as foundry binders in combination with formaldehyde, urea, phenol, and casein, for decades [12,13]. The main two monomers used in this field are 1 and 2. Table 3 summarizes their proportions in different commercial phenolic resins [12],... 

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. 

Phenolic resin Phenol and formaldehyde Wood adhesive, moulding compounds, foundry binders, laminate mouldings, electrical laminates, ablative coating casting and fibre composites for household appliances, automotive, aircraft construction and accessories, electrical and lighting industries... 

Urea Urea and formaldehyde Moulding compounds, textile auxiliaries, wood materials, foundry binder, foams... 

Cured furfuryl alcohol polymers have outstanding heat and chemical resistance and find use in cements for chemical plant, adhesives and foundry binders. 

Urea-formaldehyde (UF) resins are mainly used as adhesives for wood. Laminated sheets (tables and counter tops) are a major application for melamine resins, which stay in the outer decorative surface. Molding compounds, their first big application, is still a major market, taking advantage of their extreme hardness and heat resistance. Coatings, textile finishing, paper additives, leather tanning and foundry binders, for which methanol- or butanol-etherified resins are usually employed, are important markets discussed in Ref 203. 

Casting composition comprises a monomer and/or a polymer, a metal or ceramic powder and a solvent." Polymer used is polycarbonate, but many other polymers can be successfiilly used. Water and polar protic solvents can be used." Cycloalkanes are used as a solvents of foundry binders. ... 

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