Patent GB-851414-A (GB)
Title: Vitreous fibres coated with phenol-formaldehyde resins
IPC: C03C25/34
Filed: 1957-02-07
Abstract: Phenol-formaldehyde resins may be purified from metallic impurities by passage through a cation-exchanger.  The cation-exchanger may have been regenerated with acids (e.g. HCl), ammonia, ammonium salts (chloride, sulphate), volatile organic amines (mono-, di-, or tri-ethanol-amine, morpholine, methylamine or ethylamine), or their salts (ethanolamine- or triethanolamine-acetate).  It is preferred that an excess of the exchanger be used so that the resin is substantially free of metals, and it is also preferred that the final pH be in the range 5-7, which may be achieved by the addition of ammonia or a volatile organic amine.  The resultant solution or dispersion is then used to coat glass, rock or mineral wool fibres (see Group VIII) and is hardened by heating in situ to produce e.g. resilient glass wool, or glass rods (see Group IV(c)).  In the example a phenolformaldehyde resin which had been prepared in the presence of NaOH, was passed through a tower containing a sulphonated styrene/divinyl benzene co-polymer which had been regenerated with HCl.  The resultant purified resin dispersion was then mixed with a hydrocarbon mineral oil emulsified with ammonium stearate, aluminium sulphate, and an aqueous emulsion of purified wood rosin.  It is also stated that the resin may be mixed with an acid buffer before application to the mineral fibres:-(i) a regenerated ion-exchange resin of the type used to purify the resin; (ii) non-volatile acids, e.g., benzoic, maleic succinic, oxalic, salicylic. lactic, sulphenic, benzene sulphonic, naphthol sulphamic or phenol sulphonic; (iii) salts of non-volatile acids, of which the non-acid part is volatile, e.g. ammonium sulphate or phosphate, or monoethanolamine lactate. Reference has been directed by the Comptroller to Specification 796,515.ALSO:Glass, rock or mineral wool fibres are coated by (i) purifying a phenol-formaldehyde resin from metallic impurities by passage through a cation exchanger (see Group IV(a)), (ii) applying the purified resin in suspension or solution to the fibres, and (iii) heating the fibres to harden the resin and form a hard coating on the fibres, which may be in the form of, e.g., resilient glass wool or glass rods (see Group VIII).  In the example a purified phenol-formaldehyde resin dispersion is mixed with a hydrocarbon mineral oil emulsified with ammonium stearate, aluminium sulphate, and an aqueous emulsion of purified wood rosin, and (a) sprayed on to glass fibres as they are formed by steam blasts and cured in an oven at 400 DEG -500 DEG F. to make glass wool, or (b) applied by pad applicator to continuous glass fibres as they are formed, a bundle of such fibres being re-dipped into the dispersion and being cured at 400 DEG F. for 10 minutes to form a glass rod.  It is also stated that the resin may be mixed with an acid buffer before application to the mineral fibres, specified buffers being (i) a regenerated ion-exchange resin of the type used to purify the resin, (ii) non-volatile acids, e.g. benzoic, maleic, succinic, oxalic, salicylic, lactic, sulphamic, benzene sulphonic, naphthol sulphonic, or phenol sulphonic acid, and (iii) salts of non-volatile acids, of which the non-acid part is volatile, e.g. ammonium sulphate or phosphate, or monoethanolamine lactate.  Reference has been directed by the Comptroller to Specification 796,515.