Pilkington Brothers P.l.c.

David R Cockram

Kenneth Melvin Fyles

Alkali-resistant glass fibres, in the form of continuous-filament for use as reinforcement in cementitious products, or in the form of glass wool, are given enhanced alkali resistance by the incorporation of ThO.sub.2. The fibres are formed from a glass composition comprising, in weight percentages:

Alkali-resistant glass fibres

Glass fibres for use as reinforcement in cement products are coated with a composition containing a material to protect them against the alkaline environment, which comprises at least one dihydroxybenzoic acid, preferably 2,5 dihydroxybenzoic acid, and which may also comprise a partially-cured A-stage phenol-formaldehyde resin of the water-dilutable resole type. A further coating of an epoxy resin may be applied over this composition to protect it from abrasion during handling of the fibres and preparation of the cement products. The coating composition may be applied as a size to the individual filaments immediately after they have been drawn from a bushing, or it may be applied later after the filaments have been combined into a strand.

Glass fibres for reinforcement of cement products

A composition for coating glass fibers intended for use as reinforcement in cementitious products, containing, as a protective material, at least one monocyclic or polycyclic aromatic compound which has at least three hydroxyl groups on the aromatic ring or (in a polycyclic compound) on at least one of the aromatic rings, said composition, when applied to a strand of glass fibres which is subsequently encased in a block of ordinary Portland cement paste which is allowed to cure and kept for 28 days at 50.degree. C, producing an improvement of at least 10% in the tensile strength of the strand as compared with that of a strand similarly treated and tested but without application of said composition. Preferably, the aromatic compound is soluble in a calcium hydroxide solution. A preferred compound is pyrogallol.

Polyhydroxy aromatic coating compositions for reinforcing glass fibers

A cementitious product and production method wherein the product comprises cement with reinforcing glass fibres therein which are coated with a composition which consists essentially of a protective material to reduce deterioration of the glass fibres, the material being a monocyclic or polycyclic aromatic compound which has at least three hydroxyl groups on the aromatic ring, or when a polycyclic compound is employed, on at least one of the aromatic rings. Preferably, the aromatic compound is soluble in a calcium hydroxide solution, and a preferred such compound is pyrogallol. The composition can also contain a film-forming agent such as a polyvinyl acetate of cationic character or a polyethylene glycol of non-ionic character, as well as a linking agent such as a silane.

Growing community of inventors

Wigan, United Kingdom

David R Cockram