GB2189801A - Abrasive material - Google Patents

Abstract

An abrasive material comprises abrasive particles, for example sand, crushed glass, diamond particles, crushed metal fragments or silicon carbide fragments dispersed in a kneadable composition of stiffness such that it will not flow significantly under pressures applied during abrading. A piece of the abrasive material may be held in the hand, kneaded with the fingers and used for abrading a surface by rubbing it against the surface.

Description

SPECIFICATION Abrasive material This invention relates two an abrasive material useful for grinding, cutting and polishing surfaces by hand.

Such hand operations are commonly performed bythe use of sand paper, emery cloth and like materials which comprise a carrier sheet, usually of paper or cloth, with a layer of abrasive particles secured to one surface by an adhesive. Such materials have various disadvantages. Some of the abrasive particles become detached from the adhesive during use so that the material becomes progressively less abrasive. The carrier sheet frequently becomes creased, whereupon the creases can cause score marks on the surface being worked upon. The carrier sheet may be torn orworn into holes before its whole surface has been utilized.

Dust produced by abrasion of the surface being worked upon becomes embedded in the interstices between the abrasive particles, clogging the material and reducing its abrasive quality.

As a result of these disadvantages, sand paper and like materials soon become ineffective in use. Several sheets may be used in obtaining an acceptable finish on,forexample, a piece of wooden furniture ora paint undercoat on an automobile body. Afurther disadvantage is that some of the dust produced by abrasion of the surface being worked upon is usually dispersed into the surrounding air, where it may be a health hazard.

According to this invention, an abrasive material comprises abrasive particles dispersed in a kneadable composition of stiffness such that it will not flow significantly under pressures applied during abrasion.

Further, according to the invention, a method of abrading a surface comprises rubbing the surface with a piece ofthe above-mentioned abrasive material held in the hand.

Grinding pastes are known which comprise abrasive particles dispersed in a flowable carrier medium such as oil, grease or putty-like compositions. They are used in lapping surfaces by rubbing them together with a film of grinding paste between them, and for polishing internal surfaces of bores and open-ended cavities by forcing grinding pastethrough under pressure. Such grinding pastes are, of course, required to flow in order to perform satisfactorily.

Surprisingly, it has been found thatwhen abrasive particles are dispersed in a kneadable composition of the stiffness mentioned above they are not all wholly enveloped by the composition. Particles in anyfree surface of the kneadable composition project from the surface. The surface can therefore be used for grinding, cutting or polishing another surface. The abrasive qualityofthe surface depends upon the size and nature ofthe abrasive particles and the quantity dispersed in a unit of the composition.

The kneadable composition must be cohesive and sufficiently stable for a piece to be held in the hand, but sufficiently plastic to be kneaded with the fingers. Is should have a degree of surface tackso asto retain the abrasive particles against forces applied during use, but not such as to adhere to a surface being worked upon. A degree of resilience in the kneadable composition can be advantageous.

In use, a piece of the abrasive material is held in the hand and rubbed against a surface to be ground, cutor polished. The abrasive particles are not readily detached from the kneadable composition, but if occurs then other particles migrate to the surface to take their place. Dust produced by abrasion of the surface being worked upon tends to adhere to the kneadable composition in the interstices between the abrasive particles rather than being dispersed into the surrounding air.Whilst this dust will clog the surface of the abrasive material which is being rubbed againstthe surface being worked upon,the user can easily manipulate the material from timetotime so that the dust is taken into the kneadable composition and a new surface is produced with projecting abrasive particles to be applied to the surface being worked upon. It has been fond that bythis means a small piece ofthe abrasive material of size which can conveniently be held in the hand, say abouttwenty-five cubic centimetres, can be used to produce an acceptable finish on all surfaces of a standard wooden door or of an undercoat on an automobile body.Only when the amount of dust taken into the kneadable composition begins to affect its cohesion or kneadable properties is it necessary to discard the piece.

Because at least most ofthe dust produced by abrasion of the surface being worked upon tends to adhere to the kneadable composition, hazards caused by dust are substantially eliminated. If the surface being worked upon is of a valuable material, such as a precious metal, the dust may be recovered by appropriate treatment of the abrasive material, for example by dissolving, melting or burning the kneadable composition. Likewise, the abrasive particles may be recovered.

The kneadable nature of the abrasive material ensures that it always conforms to the surface being worked upon, so there is little or no risk of causing score marks. The small piece of the abrasive material naturally tends to remain as a cohesive mass until the amount of dusttaken up affects it as mentioned. The abrasive material thus does not "wearout".

All abrasive particles commonly used in sand paper and like materials, and others not commonly so used, may be employed in the performance of the invention. Examples of abrasive particles which may be used are sand, crushed glass, diamond fragments, crushed metal fragments and silicon carbide particles. The abrasive materials according to the invention may be made by intimately mixing the abrasive particles, and any other ingredients, with the kneadable composition by methods conventionally used for producing mastic compositions, for example by milling. Examples of abrasive materials according to the invention are, in parts by weight: 1. Abrasive material suitableforwooden surfaces: Ethylene propylene rubber 10 Aliphatic hydrocarbon oil 10 Powdered glass 60 Calcium carbonate filler 20 2. Abrasive material suitable for metal surfaces: Poly iso-butylene 80 Hydrocarbon oil 18 Calcium stearate 28 Abrasive steel grit, below 0.12 mm. mesh 750 - 1,500 3. General purpose abrasive material: Ethylene propylene rubber 30 Aliphatic hydrocarbon oil 20 Hollow glass sphere filler 50 Abrasive steel grit (as above) 400 4. General purpose abrasive material: Ethylene propylene rubber 10 Aliphatic hydrocarbon oil 20 Powdered stainless steel 750 Abrasive steel grit (as above) 800 5. General purpose abrasive material: Butyl rubber 58 Calcium carbonate filler 191 Hydrocarbon oil 82 Carbon black 0.1 Titanium dioxide 14 Talcfiller 130 Hydrocarbon oil 20 Abrasive steel grit (as above) 400 - 1,000

Claims (5)

1. An abrasive material comprising abrasive particles dispersed in a kneadable composition of stiffness such that it will not flow significantly under pressures applied during abrasion.

2. An abrasive material as claimed in Claim 1 wherein the kneadable composition has stiffness sufficient to enable a piece to be held in the hand but is sufficiently plastic two be kneaded with thefingers.

3. An abrasive material substantially as hereinbefore described.

4. An abrasive material formulated according to any one of the Examples.

5. A method of abrading a surface comprising rubbing the surface with a piece of abrasive material as claimed in any preceding claim held in the hand.