Patent GB-1533029-A (GB)
Title: Synthetic fibrous buff
IPC: B24D13/08
Filed: 1976-05-11
Abstract: 1533029 Rotary buffs MINNESOTA MINING & MFG CO 11 May 1976 [12 May 1975] 19392/76 Heading B3D [Also in Division D1] A rotary buff comprises a plurality of layers of non-woven fabric fastened together, each layer being formed of adhesively bonded synthetic organic fibres. The fabric has a density of 0À1 to 0À6 grams per c.c., a thickness of at least 0À1 mm. and the fibres of each layer are no larger than 8 denier, 1 to 15 cm. long and have a break strength of at least 3À5 grams per denier. The layers may be fastened together by one or more circles of stitching and have a central opening containing a core of more rigid material. Alternatively, the stitching pattern may be spiral, square, radial, radial arc or a combination thereof. In another form which produces a puckered buffing wheel, a continuous strip may be convolutely wound around separated ends of axially aligned mandrels, the inner part of the annulus so formed being fitted on a clinch ring or being secured by stapling, sewing or adhesive to an annulus of cardboard. The fibres of the fabric are preferably of thermoplastic or thermosetting polymer, such as nylon, polyamide, polyimide, polyesters and preferably polyethylene terephthalate, high modulus viscose rayon, some acrylic polymers and modacrylic polymers. Bicomponent fibres may also be used. The fibres should have a melting or decomposition temperature of at least 175 C. so that they will not melt and smear the workpiece surface during use. The fibres are bonded together with a binder which also has a melting or decomposition temperature of at least 175 C. and may comprise acrylate polymer, acrylonitrile/butadiene polymers, polyvinyl chloride, or polyvinyl alcohol, applied as a liquid. The binder may comprise less than 60% of the total weight of the fabric. The fabric preferably has a density of 0À15 to 0À35 grams per c.c. and a thickness of 0À25 to 0À4 mm. In order that the fabric may withstand contact with a workpiece surface at 370 C. during wiping of molten solder, the fabric may be heat and flame resistant such as high temperature resistant nylon or high strength and high modulus nylon the fibres being adhered together by a flame resistant binder such as polyvinyl chloride or vinylidene chloride-butadiene. To form the fabric, a light weight open non- woven air-laid web is formed of 80 parts 3 denier, 4 cm., high modulus viscose rayon and 20 parts 1À5 denier, 4 cm., high modulus viscose rayon, the web having a weight of about 40 grams per square metre and being laid on a continuous conveyer belt for passage between nip rolls supplying a saturating solution containing 10 parts polyvinyl alcohol, 89 parts soft water, one part triethylene glycol plasticizer, 0À2 part anti-foam agent and 0À2 part surfactant, 17À5 parts of the mixture being mixed with 52À5 parts water, 0À18 parts ammonium chloride catalyst and 0À35 parts dimethylol urea insolubilizer. The coated web is then passed into a drying and curing oven. Thereafter, the web is cut into squares and stacked in piles of 25 for sewing together so that a buff can be cut therefrom. The wear of the buff was tested by rotating the buff in engagement with a head having eleven steel blades sharpened by being bevelled on one side, the middle blade being radially aligned and touching the periphery of the buff. The head is then urged against the buff with a force of 6À8 kg. and moved to-and-fro relative to the buff, the buff being weighed before and after a number of cycles to determine the wear.