The present invention relates generally to a composition and process for repairing plastics and polymers including articles made from plastics and polymers. More particularly, the present invention relates to a composition and process for repairing plastic and polymer articles through which waves of electromagnetic radiation such as laser beams or infra-red frequency can pass. More particularly the present invention relates to a composition and process for restoring plastics or polymers of digital discs, and windows of electronic equipment through which waves from remote control devices must pass. Even more particularly, the present invention relates to a composition and process for repairing the plastic or polymeric protective coating of audio or visual digital discs.

Although the present invention will be described with particular reference to a preparation or process for repairing the plastic or polymeric protective coating of audio or visual discs it is to be noted that the scope of the present invention is not so limited but rather the scope of the present invention is broader so as to include a composition and process for repairing any plastic or polymer through which waves of electromagnetic radiation may be passed. The scope of the present invention is not limited to repairing plastic or polymer to partially or fully restore the clarity of the surface to the human eye but extends further to include partially or fully restoring the transparency of the plastic or polymer to waves of electromagnetic radiation of various wavelengths.

Much of the electronic equipment and digital recording media currently in use relies on the ability to read and transmit information in digital form using waves of electromagnetic radiation, usually in the infra-red, visible and ultraviolet regions of the electromagnetic spectrum. For example, remote controllers for televisions (TV) and video cassette recorders (VCR) issue a digital infra-red signals to the detectors in TV's and VCR's to control various functions: such as turning the VCR or TV on and off, fast forwarding and rewinding a tape in a VCR, pre-programming the VCR to record from TV and soforth. The detector is a delicate electronic device which for protection usually resides behind a plastic or polymeric window of the TV or VCR. Upon detection of infra-red signals the detector converts the binary infra-red signal into on-off code signals which are converted into an electric signal which initiates the desired function in the TV or VCR.

Combinations of waves of infra-red, visible and ultraviolet radiation known as laser beams, are also used in digital disc readers to transmit information in binary code. Digital discs store sound signals and visual images as a precise sequence of binary codes. Digital discs for example, store the binary code on the surface of a disc - minute pits in the surface of the disc are the "zeros" in the binary code while the minute unpitted portions of the surface are the "ones" in the binary code. The disc contains a spiral track of these binary codes, the track being less than one micron in width and up to many hundreds of kilometres in total length. The di z is usually metal and/or coated with a thin film of meta- which in turn is covered with a protective layer of plastic or polymer, usually polycarbonate of about 1.2 millimetres thickness. The outer protective layer reduces physical damage to the disc and reduces oxidation of the disc or thin metal film by preventing direct contact between the metal film and

atmospheric oxygen.

Digital disc readers rotate the disc at high speed. A laser beam directed at the spiral track on the underside of the disc and moves across the digital disc from the centre to the edge. Because the disc spins so rapidly, it presents a flat outer surface to the laser beam. The laser beam reflects off the unpitted parts of the metal surface and is picked up by a detector which converts the pattern of reflections received into an electric signal.

One of the problems with transmission of waves of electromagnetic radiation such as laser beams is that they can be easily deflected, refracted and scattered as they move through different media. For example, if the plastic or polymeric window of an infra-red detector of a TV or VCR is scratched, the detector may not be able to detect an infra-red signal from the remote controller because the scratches deflect or refract the infra-red signal away from the detector. This problem also occurs in relation to digital discs because the protective layer is commonly made of polycarbonate or other plastics or polymers which are vulnerable to damage by scratching. Scratches not only detract from the visual appearance of the disc, they can prevent the digital disc from being played or read. Once the protective layer is scratched, the laser beam is refracted differently through the scratched portion of polycarbonate compared to the unscratched portion. Furthermore, when the laser beam hits the edges of a scratch some or all of laser beam will be dispersed. The deeper the scratch in the protective layer , the more pronounced the effects and the greater the disruption to transmission of the laser beam through the protective layer to the surface of the metal disc and back through the protective layer to the detector. The disruption to the transmission of the laser beam can be great enough to

severely interfere with or stop the laser beam from being picked up by the detector. Consequently, the sound or visual images produced by the digital disc reader can suffer distortion or disruption and ultimately the digital disc reader may be unable to pick up any information from the tracks of the digital disc.

In the past efforts have been made to repair scratched plastic and polymer windows and the protective coatings of digital discs to improve their transparency to waves of electromagnetic radiation. Many of the methods of the prior art for repairing scratched plastic and polymers involve abrading or removing the surface of the plastic or polymer, thus reducing the depth of the scratch. This can be carried out by physical means such as grinding or using a cutting and polishing compound.

For example, United States Patent Application No. 5,099,618 by H. Schmid describes a method of polishing a scratched digital disc to remove part of the polycarbonate layer. The removing of the protective layer is carried out by polishing in directions which cut across the data track of the disc. One of the problems of such a method is that each polishing removes part of the polycarbonate layer so that there is only a finite number of times that the polishing can be carried out before the protective layer is completely removed from the digital disc. Furthermore, polishing methods of this type must be carried out in a very even manner across the whole of the protective layer - if the removal of polycarbonate is uneven the disc is prone to micro-cavitation as it is rotated in a digital disc reader and no longer presents a flat surface to the laser beam.

Another method for restoring digital discs is described in WO-9521890 by M.J.Smithlin. This method uses a composition comprising waxes and polishing compounds. It

is believed that the composition smooths the sharp edges of scratches and fills up the scratches with a wax. The refractive index of the wax and polycarbonate are similar hence the laser beam is refracted similarly through the polycarbonate and the wax which fills up the scratch. One of the drawbacks of this type of composition is that the wax is relatively soft and only physically held in the scratch. Accordingly the wax wears out of the scratch over a period of time and the composition must be reapplied.

Therefore there is a need to provide a composition and process for repairing plastic or polymers which does not significantly remove material from the surface of the plastic or polymer and does not wear off or need frequent re-application. In particular there is a need to provide a process and composition for repairing the thin protective layer of plastic or polymer of a digital disc. When used herein, the term digital disc includes audio and visual digital discs including compact discs (CD's), read- write discs, digital video discs (DVD's), mini discs, video game discs, laser video discs (LVD's) and CD Ro s.

It is an aim of the present invention to provide a composition for the repair of scratched plastic or polymers, such that the scratches do not significantly interfere with the transmission of required wavelengths of electromagnetic radiation.

According to one aspect of the present invention there is provided a composition for the treatment of scratched plastic and polymers, the composition comprising microballoons and free radical organic species. The composition may comprise free radical species or compounds which readily provide free radical species in use and many suitable species of this type will be apparent to those skilled in the art. For example, suitable free radical polymers may include species such as triphenylmethyl

radical which exists in hydrocarbon solution in equilibrium with its dimer and other substituted methyl radicals, radicals produced by the oxidation of highly substituted phenols, arylamines and hydrazines. Typically the free radical organic species are free radical polymers, or free radicals which react to form free radical polymers or polymers when the composition is applied to a plastic or polymer. Typically the composition comprises between 1 and 20% by weight free radical organic species or species capable in use of forming a free radical organic species.

In a further aspect of the present invention there is provided a composition as hereinabove described for treating scratches in plastics or polymers such that the treated plastic or polymer does not significantly interfere with the transmission of required wavelengths of electromagnetic radiation through the plastic or polymer, the composition comprising microballoons and free radical polymers.

The required wavelength is any wavelength which is required to pass through the plastic or polymer. For example, when the plastic or polymer is used to cover an infra-red or micro-wave signal detector, the required wavelength is in the infra-red or micro-wave region of the electro-magnetic spectrum.

In a further aspect, the present invention provides a process for treatment of scratched plastics and polymers, the process comprising the steps of;

a) adding the aforementioned composition to the surface of a plastic or polymer, and b) rubbing the composition across the surface of the plastic or polymer.

In a further aspect of the present invention there is provided a process for treating scratches in plastics or polymers the process comprising the steps of; a) adding the aforementioned composition to the scratched surface of the plastic or polymer, and b) rubbing the composition across the scratches for a time sufficient to treat the scratches such that the scratches do not significantly interfere with the transmission of required wavelengths of electromagnetic radiation through the plastic or polymer.

According to another aspect of the present invention there is provided a process for manufacturing the aforementioned composition, the process comprising combining microballoons with a liquid comprising free radical organic species.

Without wishing to be bound by theory, it is believed that the microballoons of the composition of the current invention when rubbed against a plastic or polymer (particularly the rough edges of a scratch) causes microscopic hot spots. The heat energy is believed to be sufficient to remove electrons from the outer electron shells of the covaiently bonded atoms of the polymer or plastic molecule. Following this, free radical organic species in the composition coordinate to the electron deficient plastic or polymer molecules, forming a chemical bond. The free radical organic species bond to the plastic or polymer molecules lining the scratch, thus at least partly filling in the scratch. Optimally the free radical species completely fill in the scratch.

Typically the plastic or polymer is one of the plastics or polymers commonly used as a window for protecting detectors for electromagnetic radiation or as a coating or layer for protecting digital discs. More typically the plastic or polymer is a thermoplastic such as

cellulose derivatives, vinyl polymers, polystyrenes, pol mides, acrylic resins and the like. Even more typically the plastic or polymer is a thermoplastic based on the condensation products of phosgene (carbonyl chloride) with dihydroxy organic compounds such as diphenylol propane such as those thermoplastics commonly referred to as polycarbonates and resins of polymethyl methacrylate such as those commonly referred to as lucite or Perspex. (Perspex is a trade mark.)

In general microballoons are hollow, finely divided, low density particles of between about 20 micron and 170 micron in size. When used herein the term microballoon is intended to include hollow or solid particles. Typically the microballoons of the present invention are manufactured from or comprise a material chosen from the group comprising synthetic resins, high polymers, glass, silica or similar film-forming material. The microballoons of the present invention may be coated with a metallic, inorganic or organic coating composition such a as beryllium, fluorinated polymers (including

Teflon) and soforth. Typically the microballons of the present invention are of uniform size, having a maximum dimension ranging between 60 micron and 120 micron or more preferably between 70 micron and 90 micron. Typically the microballoons of the present invention are aspherical. More typically the microballoons are generally teardrop shaped in one dimension and/or of crescent or curved shape in one dimension.

Typically the composition of the present invention comprises between 1 and 70% by weight microballoons. More typically the composition comprises between 20 and 70% by weight microballoons or even more typically between 20 and 45% by weight microballons.

The composition of the present invention may further comprise cutting and/or polishing composition or compounds in liquid or powder form. Typically the polishing compound is finely divided particulate matter such as iron oxide (commonly known as polishing rouge) , silica or diamond dust. Inclusion of a cutting and/or polishing compound to the composition of the present invention may increase the reflectiveness of the plastic or polymer, thereby contributing to the visual appearance. Without wishing to be bound by theory, the application of the cutting and/or polishing compound is believed to help promote the removal of electrons from the outer bonding shell of the plastic or polymer molecules, thus increasing the bonding of free radical organic species to the electron deficient plastic or polymer molecules.

The composition of the present invention may further comprise hydrocarbons such as hydrocarbon or hydrocarbon waxes or mixtures of hydrocarbon oils and waxes. Preferably the hydrocarbon wax is chosen from the group comprising paraffin (microcrystalline) waxes from petroleum, microcrystalline waxes from petroleum, high heat distillates, synthetic hydrocarbons or natural waxes. For example the wax may be chosen from the group comprising bayberry wax, beeswax, candellila wax, camauba wax, cotton wax, spermaceti wax, wool wax, Japan wax, Montan wax.

Ozokerite or combinations thereof. Polyethylene of low molecular weight may be used for extending or modifying the waxes.

The composition of the present invention may comprise additional components chosen from the group comprising emulsifiers, pigments, fillers, softeners, solvents and mixtures thereof. The composition may be in any convenient form such as a powder, a semiliquid/paste or a liquid, including an emulsion or microemulsion. Typically the composition of the present invention

comprises between 1 and 70% by weight of the total composition of microballoons, between 1 and 20% by weight free radical organic species or species which in use from free radical organic species and optionally hydrocarbon oils and/or waxes and between 50 and 90% solvent such as water.

Optionally the composition of the present invention comprising microballoons and free radical organic species may be combined with cutting and/or polishing compounds and other optional components to form a single solution for application to a plastic or polymer. Alternatively the composition comprising microballoons and organic species may be applied to the plastic or polymer and repeatedly rubbed across the surface of the plastic or polymer. In addition a different composition comprising a cutting/polishing compound may be applied to the surface of the plastic or polymer and repeatedly rubbed across the surface either prior to or subsequent to application of the composition comprising microballoons or organic species.

The process of the present invention will now be further described with reference to the following non¬ limiting examples:

EXAMPLE 1

A newly manufactured audio digital disc was repeatedly scratched with glass paper such that the digital disc could not be played by an audio digital disc reader. A pea sized drop of the composition of the current invention comprising microballoons and organic free radical in a liquid hydrocarbon solvent was placed on the playing surface of the digital disc and using a fine polishing cloth, was rubbed firmly, in straight strokes on the scratched area for two minutes. Excess of the composition was removed by running warm water across the surface of the digital disc which was then patted dry using tissues. The digital disc

was then gently polished with a fine polishing cloth. The digital disc was then inserted in an audio digital disc reader and was played without distortion or other problems from start to finish.

EXAMPLE 2

A newly manufactured digital video disc (DVD) which played without apparent audio or visual flaw was scratched once across the diameter of its playing surface with the point of a 10 cm steel building nail. After application of the scratch the DVD could not be played. Approximately 5 mis of the composition of the current invention comprising microballoons, organic free radicals including aryl substituted ethane radicals and a combination cutting and polishing composition was placed on the scratched playing surface of the DVD and using a fine chamois was rubbed on the scratch for 5 minutes. Excess composition was removed by running warm water across the playing surface of the DVD which was then patted dry using a fine absorbent cloth. The DVD was then inserted in a DVD player and was played from start to finish without audio or visual distortion or interruption.

EXAMPLE 3

A composition according to the current invention was made by combining commercially available asymmetrical microballoons, hydrocarbons including carnuba wax, emulsifier, species capable of forming free radical organic radicals and water. The final composition was; water 60 wt% hydrocarbons 15 wt% microballoons 25 wt%

The hydrocarbons comprised 0.5% aromatic hydrocarbons and

95.5% aliphatic hydrocarbons.

The composition was then applied to the playing surface of a scratched audio compact digital disk and rubbed into the

scratches using a fine polishing cloth. Excess composition was removed by running warm water over the disk. The disk, which could not be played by a compact disk player prior to treatment with the composition, was able to be played after treatment without distortion or diminution of sound quality.

EXAMPLE 4

A composition according to the current invention was made by combining commercially available asymmetrical microballoons, a solution comprising an equilibrium mixture of triphenyl methyl radical and its dimer, carnuba wax, an emulsifier and methanol/water solvent. The final composition was; methanol/water 50 wt% hydrocarbons 20 wt% microballoons 30 wt%

The composition was applied to a laser video disk (LVD) which was sufficiently badly scratched that it could not be played. The composition was rubbed across the playing surface of the LVD for 8 minutes using a fine cloth. The excess was removed using a clean tissue. The LVD could then be played.

EXAMPLE 5

A composition according to the current invention was made by combining commercially available asymmetrical microballoons, a hydrocarbon solution comprising free radical polymers, an emulsifier and water. The final composition was; water 55 wt% hydrocarbons 12 wt% microballoons 33 wt%

The composition was applied to the polymeric windows of a mobile telephone which had been scratched during normal

use. The composition was rubbed into the scratched surface for 10 to 15 minutes and the excess composition removed using a damp cloth. After treatment with the composition scratches could no longer be seen. It will be readily apparent to those skilled in the art that the composition and process of the present invention can be used to repair a wide range of plastic and polymeric surfaces such as display windows of mobile phones, display windows of electronic equipment such as stereos, calculators, computers and the like. It will also be readily apparent to those skilled in the art that the composition and process of the present invention can be used to repair, or merely polish and improve the appearance of plastic and polymer items of many different types.

Advantages of the composition and process of present invention include the following:

1) the compounds used in the process are easily handled and non-toxic;

2) scratches on plastics and polymers, particularly the protective coating on digital discs can be quickly and easily removed;

3) the process can be carried out manually without the requirement of mechanised polishing;

4) the composition does not need to be re-applied to the plastic or polymer;

The process described has been advanced by explanation and many modifications may be made without departing from the spirit and scope of the invention which includes every novel feature and novel combination of features herein disclosed.

Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is understood that the invention includes all such

variations and modifications which fall within the spirit and scope.