GB2140002A

GB2140002A - Glass pane repair

Info

Publication number: GB2140002A
Application number: GB08411883A
Authority: GB
Inventors: Andrew David Barnett; Tilborg Jane Elizabeth Van; Herbert Frank Askew
Original assignee: Castrol Ltd
Current assignee: Castrol Ltd
Priority date: 1983-05-11
Filing date: 1984-05-10
Publication date: 1984-11-21
Also published as: GB8411883D0

Abstract

The temporary repair of a broken but otherwise intact pane of glass, e.g. a toughened glass car windscreen, comprises applying a substance to the glass which firstly penetrates the glass and then hardens to restore strength to the glass, the substance being substantially transparent and of similar refractive index to glass when cured. Suitable substances comprise a penetrant, a bonding agent and preferably a dewatering fluid. Appropriate bonding agents may comprise solutions of polymers, polymerisable monomers and oligomers or part-polymerised polymers.

Description

SPECIFICATION Glass pane repair This invention relates to panes of ordinary or toughened glass and particularly to carwindscreens.

In accordance with a first aspect of this invention there is provided a method of repairing a broken but intact pane of glass said method comprising applying to the surface of the pane a substance which firstly penetrates the cracks in the glass and secondly hardens to restore some strength to the pane, said substance when hardened being substantially transparent and having a refractive index similar to glass.

The expression "intact" as used herein with reference to a broken pane of glass refers to the condition in which the pane is fragmented but in which the fragments are still in place in the pane.

Preferably said substance is of a type which can be sprayed from an aerosol can or the like.

The invention finds particular application in the temporary repair of vehicle windscreens of the type comprising toughened glass.

Where toughened glass is fitted to a vehicle windscreen it sometimes occurs that a stone on hitting the windscreen at some speed shatters the glass whereupon visibility is immediately reduced and the structural strength of the glass is decreased dramatically and sometimes to the extent that mere wind pressure causes the screen to collapse. However, more frequently, apartfrom having shattered, the windscreen is still otherwise intact after the driver has succeeded in safely coming to a halt at the roadside. To be able to continue his journey, with or without a proprietary temporary windscreen fitted, the driver of the vehicle may first need to remove the shattered windscreen or at least punch a sufficiently large hole therein to enable him to see through the screen.Alternatively he can call out the emergency windscreen repair specialists, if available, although only at some considerable cost.

Nevertheless ifthewindscreen is to be removed conditions are usually far from ideal. Firstly the driver would not normally have any means of preventing thousands of glass fragments falling into the passenger compartment. Apart from being inconvenient when this does occur, fragments frequently find their way into the vehicle ventilation system where they may be ejected at any time causing some dangertothe occupants ofthe vehicle. Secondly in attempting to prevent glass falling into the vehicle, the roadside often becomes littered with fragments.

Thus our invention provides a means whereby a windscreen may be temporarily repaired at the roadside to the extent that it is rendered substantially transparent once again and is strengthened to reduce the likelihood of the windscreen collapsing due to wind pressure, the use of the windscreen wipers or indeed from being struck again by another stone. Having repaired the windscreen, the driver of the vehicle may complete his journey and replace the windscreen at a more convenient time and place and without the potential hazard presented by glass fragments being left in the vehicle or on the roadside.

With laminated windscreens the problems referred to above do not occur because even when cracked by an impact they do not shatter and fragment. Nevertheless a substance in accordance with this invention could still be employed to improve visibility in a cracked laminated windscreen.

However it has been proposed to permanently repair small cracks or pock marks in laminated windscreens, such methods being described in for instance United States Patents Nos. 3562366, 3765975 and 4165397, but such methods find no application for the in situ temporary repair of windscreens.

Apart from car windscreens the method according to the first aspect of this invention may also be employed in repairing for instance, spectacles, headlight lenses, cracked china or glass vessels and patio glass doors.

In accordance with a second aspect of this invention we provide a substance for use in a method according to the first aspect of the invention said substance being a composition comprising a penetrant to penetrate the cracks in the glass, a bonding agent and preferably a dewatering agent to neutralise the presence of any water on the glass or in the cracks in the glass.

Alternatively said substance may comprise two separate compositions, the first comprising a dewatering agent to neutralise the presence of any water on the glass or in the cracks in the glass and the second comprising a penetrantto penetrate the cracks in the glass and a bonding agent, said second composition being applied to the glass after the glass has first been dewatered by the application of said first composition.

Preferably said bonding agent is a liquid polymer solution, a liquid polymerisable monomer solution, a liquid polymerisable oligomer solution or a liquid part-polymerised polymer solution. Said bonding agent may comprise Loctite Glassbond glue manufactured by Loctite (UK) Limited and presumably in accordance with their United Kingdom Patent No.

1430422.

A liquid polymer solution may comprise solutions of polymethyl methacrylate and/or polystyrene in trichloroethane serving both as a solvent and as the penetrant. Adhesion to the glass of such solution may be improved by the addition for instance of a glycidoxysilane or other agent known to promote such adhesion.

In tests, penetration of 8% polymer solutions into windscreen cracks appeared good but solvent evaporation left insufficient polymer to improve strength or clarity. Lower molecular weight but higher concentration solutions should give an improvement in this respect.

A liquid polymerisable monomer solution may comprise solutions of styrene and/or methylmethacrylate in trichioroethane and including a polymerisation initiator. Such initiator may comprise benzoylperoxide and/or dimethylaniline.

Preferably said dewatering agent may comprise any suitable surfactant.

The invention is further described with reference to the following Examples which are illustrative merely of the principles of this invention.

Example 1 A solution of 50% (wiz) Loctite Glassbond manufactured by Loctite (UK) Limited in 1,1,2trichloroethene was prepared and poured onto a portion of broken toughened windscreen. Any tacky surface film was removed with acetone and the resulting repaired windscreen portion was then found to be strong and substantially transparent.

Example 2 A solution of 20% (W/W) Loctite Glassbond manufactured by Loctite (UK) Limited in 1,1,2trichloroethene was prepared and a broken windscreen portion treated as in Example 1 above. Again the repaired portion was found to be strong and substantially transparent.

Example 3 A first solution of 40% styrene and 1.6% benzoyl peroxide in 1,1 ,2-trichloroethene was prepared. A second solution of 40% styrene and 0.8% dimethylaniline again in 1,1,2-trichloroethene was prepared and mixed with the first. The mixture was then immediately poured onto a portion of broken toughened windscreen and left overnight. Any tacky surface was removed as in Example 1 and the repaired portion was found to be strong, although not as strong as in Examples 1 and 2 above, and substantially transparent.

Such a product as perthis example would preferably be sprayed from an aerosol comprising two separate compartments, mixing of the two components occurring in the spray or premixing in the can.

Each of the foregoing examples were tested on a dry portion of broken windscreen whereas in practise a broken windscreen may be wet. As mentioned above a dewatering agent may first be required to be applied to the windscreen or preferably form a part of the hardenable substance.

Claims

1. A method of repairing a broken but intact pane of glass said method comprising applying to the surface of the pane a substance which firstly penetrates the cracks in the glass and secondly hardens to restore some strength to the pane, said substance when hardened being substantially transparent and having a refractive index similar to that of glass.

2. A method according to claim 1 wherein said substance is applied as a spray from an aerosol can.

3. A method according to claim 1 or 2 wherein said pane of glass is a toughened glass windscreen or other window of a vehicle.

4. A substance for use in a method according to any preceding claim being a composition compris ing a penetrant to pentrate the cracks in the glass and a bonding agent.

5. A substance according to claim 4 being a composition further comprising a dewatering fluid to neutralise any water in or on the glass.

6. A substance for use in a method according to any of claims 1 to 3 being a first composition comprising a dewatering fluid to neutralise any water in or on the glass and a second composition comprising a penetrant to penetrate the cracks in the glass and a bonding agent, said send composition being applied to the glass after the glass has first been dewatered by the application of said first composition.

7. A substance according to any of claims 4 to 6 in which said bonding agent is a liquid polymer solution, a liquid polymerisable monomer solution, a liquid polymerisable oligomer solution or a liquid part-polymerised polymer solution.

8. A substance according to claim 7 in which said bonding agent is Loctite Glassbond glue manufactured by Loctite (UK) Limited.

9. A substance according to claim 7 in which said bonding agent is a solution of polymethyl methacrylate and/or polystyrene in trichloroethene.

10. A substance according to claim 7 in which said bonding agent is a solution of styrene and/or methylmethacrylate in trichloroethene and a polymerisation initiator.

11. A substance according to claim 10 in which said polymerisation initiator comprises benzoylperoxide and/or dimethylaniline.

12. A method oftemporarily repairing broken but intact panes of glass substantially as hereinbefore described with reference to the foregoing examples.

13. A substance for the temporary repair of broken but intact panes of glass substantially as hereinbefore described with reference to the foregoing examples.