FIELD OF THE INVENTION

This invention relates to the removal of a mark from glass. More particularly, the invention relates to a method of removal of a mark from a glass bottle to rejuvenate the bottle.

BACKGROUND TO THE INVENTION

Glass bottles are in wide general use particularly for the packaging of beverages and many of these

/bottles are

bottles are collected and reused. This results in a considerable reduction in cost of the beverage to the consumer.

Reuse of bottles does however result in the bottles having their outer surface marked or scuffed and consequently becoming unsightly to an extent where they can no longer be used. This scuffing first occurs on the parts of the bottle which stand proud of the majority of the bottle surface.

OBJECT OF THE INVENTION

The object of this invention is to provide a method of removing marks from glass particularly bottles.

SUMMARY OF THE INVENTION

According to this invention there is provided a method of removal of a mark from glass comprising abrading the surface of the glass with an abrasive grit of P220 to P600 roughness and subsequently polishing the abraded surface with a fine grit material.

/Further features

Further features of the invention provide for the abrading to be effected by means of aluminium oxide grit on a flexible belt the grit having a roughness of P360 to P400 and for the polishing to be effected using pumice grit of roughness in excess of PIOOO preferably in order of P1200 or corundum of a similar roughness.

The invention also provides for the abrading to be effected on a cloth backed belt and under dry conditions and for the polishing to be effected on a porous belt and under wet conditions.

The polishing can be effected using a belt sold commercially as a "3M JLS non-scratch Scotch-Brite" belt.

These and other features of this invention will become apparent from the following description of preferred embodiments of the invention wherein scuff marked bottles are subjected to rejuvenation.

Reference will be made to the accompanying drawings in which:

/Figure 1 is

Figure 1 is a general diagrammatic layout of one belt assembly in plan view; and

Figure 2 illustrates a scuffed bottle.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE DRAWINGS

As illustrated a pair of belts 1 are mounted to have their surfaces vertical and are passed around idler pulleys 2 and an adjustable or spring loaded tension applying pulley 3. Between the belts 1 is a horizontal conveyer belt or table 4 and this component of the assembly can be given a vertical reciprocating movement so that the bottles 5 will move axially and across the surface of the belts 1.

The idler pulleys can be carried on movable chains (not shown) so that the bottles 5 are transported along with the conveyor belt 4.

The belts 1 will be driven to move in the direction indicated by arrows on the drawing but at different speeds. This will cause the bottles 5 to be

/rotated and

rotated and their whole outer surfaces below their necks to be contacted by the belts 1.

In a first embodiment endless flexible clothbacked belts 1 are prepared to carry an abrading grit of aluminium oxide with a degree of roughness of between P220 and P600. Preferably the belts 1 will be those identified commercially by the code P400 KK511F having a grit of between P360 and P400 roughness.

The belts 1 are mounted in the manner shown and driven at conventional speeds. The bottles 5 to be rejuvenated are held in contact with the belts and may be moved axially back and forth across the direction of travel of the belts. The bottles 5 are also rotated and the operation is continued until sufficient bottle stock material has been abraded therefrom to remove the scuffmarks.

The operation is conducted under dry conditions and leaves the bottles with a matt finish over the abraded areas. Usually scuffing of the surface of the bottles during use take place in areas which

/stand proud

stand proud of overall outer surface of the bottle and these are the areas which are subjected to the abrasion. Figure 2 illustrates a bottle of a common shape which becomes scuffed almost exclusively over the areas indicated at 7. It will be appreciated however that where there are no such proud areas the whole bottle surfaces will be abraded.

The next step in the process is conducted in a similar manner to the first step but the belt is a porous belt of the kind known commercially as "3M TSL non-scratch Scotch Brite" belt.

The abrasive material is a pressure sensitive abrasive slurry of pumice available commercially as "Pumex 5/on" and water. The slurry is applied to the belts 1 at positions close to their contact with the bottles and indicated at 6 and the previously abraded parts of the bottle subjected to a polishing operation. Where the belt idler pulleys 2 are carried on moving chains (not shown) they follow a path which will enable the bottles to be introduced between the belts at one end and

/discharged at

discharged at the other end of the assembly automatically. Such a construction and the assembly and driving of the belts can readily be designed by competent workmen and does not form part of this invention and need not be further particularised in this specification.

The polishing operation preferably involves a grit roughness of P1200 and belt speeds for both abrading and polishing operation can satisfactorily be chosen to be between 300 and 1000 meters per second. The slurry used for polishing will be chosen to suit the belt speed and type of glass being polished. The particle size of the pumice will be between 5 Mu and 30 Mu and slurry concentration is preferably between 500g and lOOg per litre. Convenient belt size has been found to be 50 mm wide and having a length of about 2700 mm.

After polishing the bottles are washed and all unsightly marks will have been removed resulting in a bottle which is commercially acceptable for re-use.

/In a

In a second embodiment the abrading may be effected using an aluminium oxide abrasive belt known commercially as a P360 K227 belt.

The polishing operation is effected using a corundum material in the form of emery having a cloth and paper or resin impregnated paper backing. The degree of roughness of the emery will again be chosen to be in the order of P1200. The polishing is preferably conducted dry.

It will be appreciated that many variations to the specific embodiments described above may be made without departing from the scope of the invention. Different abrading grits may be chosen and other polishing material applied if circumstances so dictate. Materials which satisfactorily polish the previously abraded surface of the glass are cork and cerium oxide. The abrading operation may be conducted under wet conditions but the applicant has not found this to be preferred using aluminium oxide abrasive.

/The process

The process results in appreciably extending the useful life of many bottles which would otherwise have been destroyed or required recycling.

/CLAIMS