Patent ID: 12194659

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described on the basis of the drawings. It will be understood that the embodiments and aspects of the invention described herein are only examples and do not limit the protective scope of the claims in any way. The invention is defined by the claims and their equivalents. It will be understood that features of one aspect or embodiment of the invention can be combined with the feature of a different aspect or aspects and/or embodiments of the invention.

FIG.1shows a non-limiting example of a laminate10used in a car window glass. The laminate10comprises a polymer layer20, which is laminated as an interlayer between a first glass layer30and a second glass layer40.

The laminate10is used, in one aspect of the invention, in a car windscreen (also called windshield). It was noted in the introduction that the laminates also find application in a number of other fields and the teachings of this disclosure are not limited to laminated glass for car windscreens. In a further aspect of the invention, the laminate10comprises three glass layers between which two polymer layers are interlaid.

In one non-limiting example of the invention, the polymer layer20is made of polyvinyl butyral (PVB), which is typically used in car windscreens. Other thermoplastics can be used as the polymer layer.

FIG.3shows an example of a recycling plant for the recycling of the laminates10. It will be appreciated that the plant shown inFIG.3is merely exemplary and is not limiting of the invention. The plant includes a shredder310and a vat360. The shredder310crushes and shreds the glass laminate10mechanically. The vat360has a fluid dispenser370for dispensing separating fluid375into the vat360and a mixing device365. The vat360has an outlet390for removing materials380from the vat360. It will be noted that the shredder310and the vat360do not need to be co-located. In one aspect of the invention, at least some of the elements of the plant will have anti-adhesive PTFE coatings, which reduces the risk of clogging of the pipework in the plant. The outlet390leads to a sieving device393to sieve out the polymer pieces, a washing device395and a drying device396. Device399represents schematically a device to package and reuse the polymer pieces, which could be an extruder or a melting device.

Washing water from the washing device395can be treated in a treatment device397to enable reuse of the washing water. A filtering device394is connected to the sieving device393to clean used separating fluid375from glass particles and return the filtered separating fluid375back to the fluid dispenser370for re-use.

FIG.2shows an outline of the method for recycling of the glass laminates10of this disclosure. The glass laminates10are collected together as portions300of the glass laminates10. On arrival in step200at the recycling plant, the glass laminates10are placed into the shredder310and crushed or shredded in step210to produce glass from the glass layer30and40, as well as pieces of the polymer layer20with residual particles of glass (350), partially impregnated therein as splinters.

The pieces of the polymer layer20are separated in step220from the glass of the glass layers30,40. The glass is recycled, as is known in the art. In step240, the remaining laminate portions comprising the polymer pieces with the residual glass particles350are added to the vat360with a separation fluid375from the fluid dispenser370. The mixture of the separation fluid375and the polymer pieces is then mixed in step260in the vat360. The effect of the separation fluid375is thought to be to swell the surface of the polymer pieces and thus “expel” the glass particles from the surface of the polymer pieces. This is achieved at a given temperature, for example between 0° C. and 50° C., at atmospheric pressure during a treatment time of between 10 and 180 minutes.

The material380comprising the separating fluid375and the polymer pieces, as well as any residual glass pieces, can be removed in step270from the vat360. The polymer pieces can be removed in step280by sieving in device393. It will be noted that the separating fluid375and any residual glass pieces pass through the device393. The separating fluid375is then filtered with device394for recycling in step281and placed back into the fluid dispenser370. The filtering step281removes substantially all of the residual glass pieces and any other impurities from the separating fluid375.

The polymer pieces are washed in washing water in step283in a washer395and dried in step286in the dryer396. The polymer pieces can be extruded or packaged for reuse in step290, e.g., for use in the manufacture of new windshields. The washing water needs to be treated in step293before the water is also reused. The treatment of the washing water is done by filtering out any glass and other impurity particles from the washing water and by removing any remaining separating fluid from the washing water in the treatment device397. The filtering and the removal of the separating fluid is done, for example, by regular and/or cross flow filtration techniques and reverse osmosis, which allows reclaiming chemicals of the separation fluid from the washing water.

The separation fluid375used in the vat360and coming from the fluid dispenser370is a solution of a water-soluble alcohol in water. Non-limiting examples of such water-soluble alcohols include lower alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec.-butanol, tert.-butanol and 2-methylpropanol, pentanols, benzyl alcohol, glycol ethers such as methyl glycol, ethyl glycol, propyl glycol, isopropyl glycol, butyl glycol, butyl diglycol, butyl triglycol, methyl diglycol, methyl triglycol, ethyl diglycol, phenyl glycol, phenoxy propanol, methoxy propanol, methoxy butanol, ethoxy propanol, propylene glycol butyl ether, di(propylene glycol)butyl ether, tri(propylene glycol) methyl ether, tri(propylene glycol)butyl ether and others, such as diacetone alcohol or ethyl lactate.

The separation fluid375is kept between 0 and 50° C., and at pH values of around7. The speed of the reaction depends to a large extent on the diffusion rate into the surface of the polymer layer, which itself is governed by the choice of the alcohol, the concentration of the alcohol, and the temperature.

Examples of the separating fluid and process conditions

The examples listed below are merely illustrative examples of a suitable separating fluid and the process conditions and are not limiting of the invention.

A 25% solution of butyl diglycol in water was used as the separating medium375. The treatment time was 2 hours at 40° C. at normal atmospheric pressure.

A 25% solution of butyl diglycol in water was used as the separating medium375. The treatment time was 3 hours at 30° C. at normal atmospheric pressure.

A 25% solution of butyl diglycol in water was used as the separating medium375. The treatment time was 2 hours at 35° C. at normal atmospheric pressure.

A 20% solution of butyl diglycol in water was used as the separating medium375. The treatment time was 2 hours at 40° C. at normal atmospheric pressure.

A 10% solution of butyl glycol in water was used as the separating medium375. The treatment time was 1.5 hours at 40° C. at normal atmospheric pressure.