Patent GB-481324-A (GB)
Title: Improved manufacture of cork composition
IPC: B27K7/00
Filed: 1937-02-01
Abstract: A cork composition having substantially the unimpaired properties of cork itself comprises cork granules and a binder of bodied tung oil and natural or synthetic resin, the quantity of the binder being only that sufficient to cement the granules together.  The binder preferably contains also a solvent and cork plasticizer such as glycerine.  The tung oil is bodied by heating in an open kettle to a temperature of 450-500 DEG  F. for about an hour when the oil has such a consistency that when a rod is dipped therein and raised a string of oil is formed.  In an example, the treated oil is mixed with glycerine, cooled to about 180-200 DEG  F. and mixed with a phenol formaldehyde resin prepared from 16 lb. of phenol to 1 lb. of formaldehyde solution (37-40 per cent) and about 2 3/4 oz. of oxalic acid.  Just before mixing the binder with the cork granules a hardener, e.g. hexamethylenetetramine, is added.  Suitable quantities used are 150 parts of resin, 50 parts of bodied tung oil glycerine solution and 5 per cent or less of hardener.  About three pounds of the binder are mixed with 12-13 lb. of cork granules, forming a mass of coated granules which may be moulded at a temperature of about 290-300 DEG  F. for about two hours.  The coated granules are non-tacky and may be stored before being moulded.  Glycol or sulphonated castor oil may be used instead of glycerine whenever taste and odour imparting properties are not important.  Other synthetic resins such as urea formaldehyde resin, alkyd resins or cumarone resins may be used, or natural resins such as dammar and copal.  A small quantity of wax may be added to the binder.ALSO:A cork composition having substantially the unimpaired properties of cork itself comprises cork granules and a binder of bodied tung oil and natural or synthetic resin, the quantity of the binder being only that sufficient to cement the granules together.  The binder preferably contains also a solvent and cork plasticizer such as glycerine.  The tung oil is bodied by heating in an open kettle to a temperature of 450-500 DEG  F. for about an hour when the oil has such a consistency that when a rod is dipped therein and raised a string of oil is formed.  In an example, the treated oil is mixed with glycerine, cooled to about 180-200 DEG  F. and mixed with a phenol formaldehyde resin prepared from 16 lb. of phenol to 1 lb. of formaldehyde solution (37-40 per cent) and about 2 3/4 oz. of oxalic acid.  Just before mixing the binder with the cork granules a hardener, e.g. hexamethylenetetramine is added.  Suitable quantities used are 150 parts of resin, 50 parts of bodied tung oil glycerine solution and 5 per cent or less of hardener.  About three pounds of the binder are mixed with 12-13 lb. of cork granules, forming a mass of coated granules which may be moulded at a temperature of about 290-300 DEG  F. for about two hours.  The coated granules are non-tacky and may be stored before being moulded.  Glycol or sulphonated castor oil may be used instead of glycerine whenever taste and odour imparting properties are not important.  Other synthetic resins such as urea formaldehyde resin, alkyd resins or p cumarone resins may be used, or natural resins such as dammar and copal.  A small quantity of wax may be added to the binder.