Patent GB-1017473-A (GB)
Title: Temperature resistant glass fibre reinforced articles
IPC: C03C25/47
Filed: 1963-09-23
Abstract: 1,017,473. Agglutinated fibrous materials. OWENS-CORNING FIBERGLASS CORPORATION. Sept. 23,1963 [Oct. 12,1962], No. 37348/63. Heading D1R. A glass fibre board or moulded product comprises a mat of intermeshed glass fibres and a hardened synthetic resin binder which is present in the form of a coating covering at least 40% substantially of the surface of the fibres and which bonds the fibres one to another at points of contact, wherein there is dispersed in the binder in surface contact with the fibres a devitrifying agent (a) consisting of one or more of the following: asbestine, wollastonite, talc or an oxide, hydroxide, carbonate or silicate of an alkaline earth metal together with a devitrifying accelerator (b) consisting of one or more of the following: titanium dioxide or an oxide, hydroxide, carbonate or silicate of iron, zirconium or chromium, it being provided that if (a) is asbestine and (b) is titanium dioxide the weight ratio of asbestine to titanium dioxide is between 1:1 and 19:1 and, if (a) or (b) is replaced partly or completely by another among the substances the alternative substance is present in amount corresponding by volume with the asbestine or titanium dioxide respectively replaced, to maintain a ratio equivalent to the said weight ratio 1:1 to 19: 1 of asbestine to titanium dioxide. The particle size of the devitrifying agent should be substantially finer than 200 mesh and preferably, such that nearly all will pass a 325 mesh sieve. At least 50% thereof by weight has a particle size finer than 20 microns and, ideally, less than 10 microns. The devitrifying agent may be applied as a constituent of the binder and must not be so finely divided as to cause undue thickening of the binder. Finely divided fibrous materials are more effective than non-fibrous materials. The devitrifying agent provides-nuclei on the glass fibre surfaces and these nuclei greatly accelerate the rate at which devitrification occurs. The par ticle size` of the accelerator should be substantially finer than 200 mesh and preferably, such that nearly all will pass a 325 mesh sieve and at least 50% thereof by weight has a particle size finer than 20 microns and, ideally, less than 10 microns In apparatus, Fig. 1, for producing the glass fibre boards, streams of molten glass are drawn downwardly from a tank 11 through small orifices in bushing tips 12 by downwardly projected steam blasts from a blower 13. The fibres thus formed are projected downwardly through a hood 14 in which spray heads (not shown) supply the binder. A suction box 17 draws the fibres and associated binder on to foraminous conveyer 15 to form a fibrous mass 18 which is compressed by a member 19 driven in the same direction as-and at the same speed as the belt 15. The mass 18 passes through a curing oven 20. Subsequently the edges of the board material 21 are trimmed and it is cut into lengths. Alternatively, the boards may be formed by drawing a single large diameter stream of molten glass into a rotating centrifuge basket and through peripheral orifices therein so that the glass is projected into a stream of gases which carry the fibres on to a foraminous conveyer, the binder being associated with the fibres as they are projected towards the conveyer. In a third method, streams of molten glass are drawn from a tank, cooled into rodlets which are introduced into burners to cause re-softening thereof and projected by a high velocity-blast of flame and combustion products on to a foraminous conveyer, the binder being added during the latter step. The fibrous board may contain a high temperature binder constituent comprising finely divided clay Specified aluminium silicate clays are ball clays, kaolins and montmorillonites, e.g. bentonite. A devifrifyirig agent and a devitrification accelera tor may be contained in the binder. The clay-containing binder may be applied to a board 22, Fig. 3 (not shown) on a foraminous conveyer 23 by overflowing from a reservoir 25 and running down an inclined plate 24, the reservoir 25 being supplied  by a pipe 26. Impregnation is facilitated by suction applied by a box 28 which may have a sliding damper on the top thereof. The binder solution may contain a surface active agent, e.g. the dioctyl ester of sodium sulphosuccinic acid, and an anti-foam agent.  A specified binder is made from phenol, for- , madehyde and dicyandiamide and includes finely divided barium sulphate as a consequence of using barium hydrate as a condensing agent and ultimate neutralisation with sulphuric acid. Other specified binders'-are'urea-formaldehyde condensation pro-  ducts, melamirie -formaldehyde condensation pro- ;  ducts, dicyandiamide-formaldehyde condensation products, neoprene, butadiene-acrylonitrile copolymers-, acrylic-polyvinyl chloride-, polvinyl-alcohol-, and polyvinyl acetate latices ,starch, corn  syrup and flour. Pinewood pitch extract of specified composition may be added to the binder. Exfoliated vermiculite may be added to the fibres along with the binder to increase the resistance of the'board to elevated temperatures. Also, asbestos and glass foam pellets may be similarly added. Ammonium hydroxide may be added for pH control. Silanes and silicones may be added to improve coupling with the binder or durability or both. Emulsified mineral oils may be added to improve the feel of,the product. The board may be impregnated additionally with cementitious materials such as magnesium oxy-sulphate cements, magnesium dxy-chloride cements, gypsum or Portland cement.