Patent GB-957331-A (GB)
Title: Polishing or abrasive product
IPC: B24D13/00
Filed: 1961-04-10
Abstract: <PICT:0957331/C3/1> <PICT:0957331/C3/2> <PICT:0957331/C3/3> An abrasive or polishing article is made by first treating an open non-woven web having substantial loft and a high proportion of internal voids of superposed randomly dispersed relatively short flexible tough synthetic organic fibres with an elastomeric binder (hereinafter referred to as the binder adhesive) to bond the fibres at points of intersection and contact so as to form a resilient web, and then subjecting this web to a roll-coating operation utilizing as the coating material a solvent or dispersant having no, or at most only a slight, softening effect on the binder and which contains an adhesive (hereinafter referred to as the maker adhesive) which is substantially harder and tougher than the binder adhesive, so that the maker adhesive overlies the binder adhesive and extends further than the latter along the length of the individual fibres.  Through the action of roll coating the maker adhesive tends to deposit along the fibres in the form of elongated strings, and some of it also surrounds the binder adhesive at fibre intersections.  Generally, the maker adhesive also contains a slurry of an abrasive, although this is not essential. Specified fibres are nylon, a condensate of dimethyl terephthalate and ethylene glycol, polyacrylonitrile, and a copolymer of acrylonitrile and vinyl chloride.  Specified binder adhesives are synthetic rubber latex, nitrile rubber latex, butadiene-acrylonitrile latex, neoprene, natural rubber, phenolic, melamine and urea-formaldehyde resins.  Specified maker adhesives are polyurethanes, phenolic, epoxy, polyisocyanate and phenol-formaldehyde resins.  Specified abrasive grains are silicon carbide, aluminium oxide, flint and emery.  As shown in Fig. 1, fibres 11 of synthetic organic material delivered from cutter 12 are agitated by air blasts from nozzles 14 and deposited on conveyer belt 13 to form web 10 to which bonding adhesive 15 is applied by spray nozzles 16 and which then passes through heating zone 17 to cover the adhesive.  The web then passes through roll-coater 18 comprising lower roll 20 which rotates in a bath 21 of maker adhesive-abrasive slurry 22 and upper roll 19, after which the web passes through heating zone 23 partially to set the maker adhesive.  The web is wound to form a roll 25 and subjected to further heating in zone 26 finally to cure the maker adhesive. The roll 25 may then be cut transversely as shown at 27 to form abrasive discs 28. Alternatively, after leaving roll-coater 18 the web may be completely covered in zone 23 and abrasive discs may be die cut from the flat web.  Fig. 2B illustrates a web of fibres 31 after application of the binder adhesive, the intersections 30 of the fibres being encased by globules 32 of adhesive; occasional globules 321 also adhere along the lenghts of the fibres.  Fig. 2C illustrates the web after application of the maker adhesive containing abrasive grains. The fibres 31 are fairly well coated throughout their lengths with maker adhesive 33 and abrasive grains 34 which also tend to form a coating over the globules 32 of binder adhesive.