GB925105A - Improvements in the manufacture of resins - Google Patents

Abstract

There are reacted together by heating, preferably to 130 DEG -185 DEG C.: (a) phosphoric anhydride, a hydration product thereof or a dehydration product of phosphoric acid, (b) orthoboric acid, boric oxide or mixtures of them, and (c) one or more dihydric and/or trihydric phenols or a mixture of a dihydric and/or a trihydric phenol with not more than an equimolecular amount of a monohydric phenol. For every 6 gram atom of phosphorus in (a), there are 0,2-3,3, preferably 1,1-2,2, gram atom of boron in (b) and at least 0,5 gram mole of (c), the number of gram atoms of boron not exceeding the number of gram mole of (c), and the sum of the number of gram atoms of boron and the number of gram moles of (c) being 1-6,6. The components may all be heated together, or any two reacted and the third added and heating continued. When P2O5 is used as (a), the heat generated by adding a small quantity of water to the mixture will initiate the reaction. 3 hrs. heating at 180 DEG C. is usually sufficient. The thermoplastic products may be cured by heating with formaldehyde or a formaldehyde donor to at least 200 DEG C., or by heating alone to a higher temperature. The thermoplastic resins, dissolved in a solvent, dispersed in water, or without either treatment, may be mixed with e.g. asbestos fibre, mica or aluminium powder and later cured to give mouldings, laminates, surface coatings or bonding agents. Although preparation and curing are usually done separately, the resin components, fillers and, if added, formaldehyde or a formaldehyde donor, may be mixed and heated to above 200 DEG C., preferably in a mould, to give a cured product. Specification 807,851 is referred to.