Patent GB-557967-A (GB)
Title: Improvements in or relating to flexible abrasive articles and processes for producing the same
IPC: B24D11/00
Filed: 1941-02-13
Abstract: 557,967. Resinous condensation products. STEVENS, A. H. (Minnesota Mining & Manufacturing Co.). Feb. 13, 1941, No. 1991. Drawings to Specification. [Class 2 (iii)] [Also in Group XXIII] A flexible abrasive article such as sandpaper comprises a cellulosic backing, e.g., paper or fabric, a layer of abrasive particles and, as a pre-size, back-size, binder or sand-size, a composition comprising an oil-compatible alkyd resin, an oil-reactive or oil-modified phenolaldehyde resin and a fatty oil. The proportion of the phenol-aldehyde resin exceeds that of the alkyd resin. The composition may comprise 3-35 per cent., preferably 10 per cent., of the phenol-aldehyde resin and fatty oil. Suitable phenol-aldehyde resins may be made by (1) melting the resin (1 part) in Chinawood oil (2.5-3 parts) and heating to 225‹-250‹ C. A drier, e.g. shellac, red lead, litharge, manganese oxide, borate, resinate or tungate may be heated with the oil prior to incorporation of the resin. (2) Heating tung oil with p-tert-amyl- or ptert-butyl phenol in the presence of aluminium chloride, sulphuric acid or hydrochloric acid, and, after separation of the aqueous material, heating the oily layer with formaldehyde. A further quantity of formaldehyde or hexamethylenetetramine may be added and heating continued. (3) Heating alkylphenols with formaldehyde in equimolar ratio in the presence of alkaline or acid catalysts, incorporating a fatty oil and drier and again heating at 225‹- 250‹ C. The alkyd resin, driers and thinners, e.g. oleum spirits, solvent naphtha, white spirit, lacquerpetrol and turpentine, are then added. Suitable alkyd resins are made (1) by heating glycerine and phthalic anhydride at 150‹ -175‹ C. adding drying oil fatty acids and additional phthalic anhydride and heating further at 210‹-225‹C. Suitable drying oil fatty acids are those from linseed, chinawood or perilla oils, or linoleic, linolic, linolenic and eleostearic acids. Oleic, butyric, succinic, citric, benzoic, maleic, glutaric, suberic, camphoric, adipic, linolic, eleostearic, linolenic or linoleic acids may replace part of the phthalic anhydride. Alternatively, the drying oil acids may be heated with phthalic anhydride at 160‹ C. glycerine added and heating continued at 200‹ C. (2) A glycerol-phthalic anhydride resin and chinawood, linseed, perilla, soya bean, castor or cotton seed oils are dispersed in benzyl benzoate and heated. The modified resin is precipitated by addition of a non-solvent ; (3) cresol and paraldehyde or furfural are refluxed in the presence of hydrochloric acid, phthalic anhydride and glycerol, linseed oil fatty acids are added and the mixture heated at 250‹ C. in an inert atmosphere. Resin may be added to the initial phenol-aldehyde components ; (4) Glycerine, glycol or diethylene glycol and the drying oil acids are heated at 200‹ C., phthalic anhydride is added and heating continued at 200‹ - 220‹ C.; (5) Phthalic anhydride, glycerine, drying oil acids and coumarone resin are heated at 250‹ C. In the above examples phthalic anhydride may be replaced by a polycarboxylic acid made by reacting chloracetic acid with a phenol-aldehyde partial condensation product. In an example of the production of sand-paper, the backing is pre-sized, a binder coating of the alkyd resin-phenol-aldehyde resin-oil composition is applied to hold an abrasive and a backsize is applied. The pre-size comprises an oilcompatible alkyd resin and the back-size may be the same as either the pre-size or binder.