CURING REPAIR RESIN

Abstract

The present invention provides a repair resin composition for repairing breaks in a vehicle windscreen and curing units for curing the repair resin after it has been inserted into the break. The present invention also provides a method of repairing a vehicle windscreen, comprising inserting a resin into a repair zone, wherein the resin comprises a photoinitiator that activates when exposed to light of an activation wavelength, wherein the activation wavelength is between 370 nm and 425 nm, and curing the resin by emitting light including light within the activation wavelength range onto the repair zone.

Claims

1. A method of repairing a vehicle windscreen, comprising: inserting a repair resin into a repair zone, wherein the resin includes a photoinitiator that activates when exposed to light of an activation wavelength, wherein the activation wavelength is between 370 nm and 425 nm; and enhancing curing of the resin by emitting light including light within the activation wavelength range onto the repair zone.

2. The method of claim 1, wherein the resin will not cure in an enhanced manner at activation wavelengths of 365 nm or less but rather at wavelengths is between 370 nm and 425 nm

3. The method of claim 1, wherein the light is emitted by an LED device and is rated to emit at a single rated wavelength; and the device is capable of only emitting at that rated wavelength (with the exception of any leakage wavelengths above and below the rated LED wavelength).

4. The method of claim 1, wherein at least 80% wt of the resin is not reactive to UV light.

5. The method of claim 1, wherein 1 to 5% wt of the resin activates upon exposure to light of the activation wavelength.

6. The method of claim 1, wherein the resin does not comprise any components that absorb UV light other than the photoinitiator.

7. The method of claim 1, wherein the rated activation wavelength is between 370 nm to 400 nm.

8. The method of claim 1, wherein the rated activation wavelength is in the range between 380 nm and 390 nm.

9. The method of claim 1, wherein the light emitted onto the repair zone has an intensity of at least 10 mW/cm.sup.2.

10. The method of claim 1, wherein the light is applied to the repair zone using at least one LED.

11. The method of claim 8, wherein the at least one LED is spaced at least 15 mm away from the repair zone in a perpendicular direction.

12. The method of claim 10, wherein the at least one LED is spaced less than 10 cm away from the repair zone in a perpendicular direction.

13. The method of claim 1, comprising the initial step of mounting a curing unit to the windscreen using a mount apparatus spaced at least 10 cm from the centre of the repair zone.

14. The method of claim 13, wherein the mount apparatus comprises a suction mount.

15. The method of claim 1, further comprising applying pressure to the resin inserted into the repair zone during the curing of the resin.

16. The method of claim 15, comprising using a device positioned on the exterior side of the windscreen to apply the pressure to the resin.

17. A curing unit for use in repairing a vehicle windscreen, comprising: a mount apparatus for securing the curing unit to the windscreen; and a light emitter configured to emit light onto a repair zone, wherein: a) the mount apparatus is spaced at least 10 cm away from the light emitter; the light emitter being mounted by means of a rigid arm which is not able to deflect or bend; and/or b) the light is emitted by an LED device and is rated to emit at a single rated wavelength; and the device is capable of only emitting at that rated wavelength (other than any leakage wavelengths above and below the rated LED wavelength).

18. The curing unit of claim 17, wherein the mount apparatus comprises a suction mount.

19. The curing unit of claim 17, wherein the unit is not capable of emitting a wavelength of 365 nm or less.

20. The curing unit of claim 17, wherein the light emitter is configured to emit light of a wavelength between 370 nm and 400 nm.

21. The curing unit of claim 17, wherein the light emitter is configured to emit light of a wavelength between 380 nm and 390 nm.

22. The curing unit of claim 17, wherein the rigid arm is spaced at least 15 mm above a base of the mount apparatus in a perpendicular direction.

23. A windscreen repair resin composition comprising: 30 to 80% wt acrylates; 4 to 25% wt acids; 0.5 to 10% wt oxysilanes; and 1 to 10% wt UV activated photoinitiator.

24. The resin of claim 23, comprising: 40 to 70% wt acrylates; 6 to 18% wt acids; 1 to 5% wt oxysilanes; and 1 to 7% wt UV activated photoinitiator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0112] FIG. 1—shows a graph of the transmission of light through a vehicle glazing panel as a function of the wavelength of the light;

[0113] FIG. 2—shows a perspective view of a curing unit according to the present invention;

[0114] FIG. 3—shows a diagram of a side on view of a curing unit according to the present invention;

[0115] FIG. 4—shows the curing unit of FIG. 3 when turned on; and

[0116] FIG. 5—is a diagram illustrating the curing units of FIG. 2 or 3 in use repairing a vehicle windscreen.

[0117] The skilled person would appreciate that none of these figures are drawn to scale, nor are the relative sizes of any features depicted accurately. The drawings are for illustrative purposes only.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0118] FIG. 1 is a diagram showing how the percentage of light transmitted through a vehicle windscreen varies in accordance with the wavelength of the light. As demonstrated, the longer the wavelength of the light, the more light penetrates through the windscreen. However, as the wavelength (λ) of light increases the energy (e) of the light decreases, as per the below equation:

[00001]$\begin{array}{cc}e=\frac{h.Math.c}{\lambda }.& \left(1\right)\end{array}$ [0119] where h is the Planck constant and c is the speed of light.

[0120] The higher the energy of the light the quicker the curing process will be. In order to obtain optimum curing of the resin there needs to be a balance between ensuring sufficient light is transmitted through the windscreen and that the curing light has a high enough energy to activate the resin in an acceptable exposure time.

[0121] In one embodiment of the present invention the optimum wavelength is 385 nm±5 nm. This must also be the activation wavelength of the photoinitiator used in the corresponding repair resin. Almost 90% of light with this wavelength is transmitted through a vehicle windscreen, as shown in FIG. 1. In comparison, the mercury vapour bulbs used in known curing units for windscreen repair processes only have about 60% to 70% transmission through the windscreen.

[0122] An embodiment of a curing unit according to the present invention is shown in FIG. 2. The curing unit 10 comprises an LED array 11 connected to the underside of a support arm 13. A suction mount 12 is also attached to the support arm 13. The suction mount 12 is configured to securely mount the curing unit 10 onto a vehicle windscreen.

[0123] A handle 14 s attached to the curing unit 10 to be gripped by the user. This aids in removing the suction mount 12 from the windscreen after the curing process has been completed.

[0124] The LED array 11 comprises a plurality of LEDs (not shown), each LED configured to emit light of a single specific wavelength between 370 nm to 420 nm. The intensity of the light emitted by the LED array is at least 15 mw/cm.sup.2 in order to ensure that sufficient area of the windscreen is illuminated at the required from the emitter positioned above the windscreen. Typically an LED light emitter is used which has a single rated activation wavelength within the specified range. By rated activation wavelength we mean that the rating (or technical specification) of the LED is a single wavelength (or narrow wavelength band) within the specified range. There may be of course leakage or trace wavelengths emitted slightly above or below the rated LED activation wavelength (or narrow wavelength band).

[0125] In some embodiments the wavelength may be between 370 nm to 425 nm, or between 380 nm to 390 nm.

[0126] The curing unit 10 is configured to be used to cure a windscreen repair resin after the resin has been inserted into a break in the windscreen. The activation wavelength of the resin must be in the range of 370 nm to 425 nm to ensure that it is correctly cured by the light emitted from the curing unit 10. As detailed in relation to FIG. 1, this wavelength range was selected as it provides optimum curing of the resin by obtaining a balance between ensuring sufficient light from the curing unit is transmitted through the windscreen and that the curing light has a high enough energy to activate the resin in an acceptable exposure time.

[0127] When cured, the repair resin should ideally have the same mechanical and optical properties as the windscreen itself. As described in the background section, the repair resin comprises a photoinitiator substance which triggers the curing of the other components of the repair resin from a liquid to a solid substance. The photoinitiator must absorb and be activated by the light emitted from the curing unit. The other components of the resin are selected to ensure that they can be cured by the photoinitiator when it is activated and that, upon curing, the solid repair resin has the desired mechanical and optical properties.

[0128] The repair resin may comprise benzyl dimethyl ketal and/or 2,2-dimethoxy-1,2-diphenyl ethanone as the photoinitiator(s). These photoinitiators are activated by curing light in the wavelength range of 370 nm to 400 nm, which corresponds to the wavelength of the LED array 11. It will be appreciated by the skilled person that there may be other suitable photoinitiators which could be used in the resin. The photoinitiator activation wavelength is matched to the single rated wavelength emitted by the LED emitter.

[0129] The composition of the resin is substantially such that the bulk of the resin will not cure in an enhanced manner at activation wavelengths of 365 nm or less but rather at wavelengths is between 370 nm and 425 nm. Typically at least 80% wt of the resin is not reactive to UV light, but typically 1 to 5% wt of the resin (i.e. the photoinitiator) activates upon exposure to light of the activation wavelength. Put another way, the resin does not effectively comprise any components that absorb the LED emitted wavelength other than the photoinitiator. Also the resin does not effectively comprise any components that absorb light of 365 nm or less.

[0130] The resin composition may comprise: 40 to 70% wt acrylates; 6 to 18% wt acids; 1 to 5% wt oxysilanes; and 1 to 7% wt of the photoinitiator(s). This composition provides the required structure and viscosity of the resin whilst ensuring that it cures rapidly and effectively upon activation of the photoinitiator.

[0131] In some embodiments, the resin composition may comprise: 15 to 20% wt 2-hydroxyethyl methacrylate; 25 to 49% wt isobornyl acrylate; 1 to 4% wt maleic acid; 5 to 14% wt decanedioic acid; 1 to 4% wt glycidoxypropyltrimethoxysilane; and 1 to 5% wt of the photoinitiator(s), wherein the photoinitiator(s) is/are benzyl dimethyl ketal and/or 2,2-dimethoxy-1,2-diphenyl ethanone.

[0132] A plurality of slots or apertures 15 are provided in an upper surface of the support arm 13 above the LED array 11. These slots or apertures 15 are provided to cool the LED array 11 during operation, by allowing waste heat to escape.

[0133] The LED array 11 is positioned at least 15 mm above the base of the suction mount 13. This ensures that the light emitted from the LED array 11 creates a large enough exposure area to cover a typical repair zone on a windscreen. In this embodiment, the exposure area has a diameter of 50 mm or less.

[0134] After inserting the repair resin into the repair zone on the windscreen, the curing unit 10 is used. When the user turns the LED array 11 on, for example by pressing a start or power button (not shown), the LED array 11 emits light for a predetermined exposure time of 180 seconds. An internal timer device (not shown) controls the predetermined exposure time and automatically switches off the LED array 11 on expiry of the predetermined exposure time. In other embodiments the predetermined exposure time may be any duration of 60 seconds or more.

[0135] Another example of a curing unit 20 is shown in FIG. 3. The curing unit 20 comprises a light source 21 and a suction mount 22, both attached to a support arm 23. The support arm 23 is rigidly fixed with respect to the suction mount and this is important to ensure fixed and consistent positioning of the LED emitter above the windscreen. The support arm 23 extends in a substantially transverse or horizontal direction. The support arm 23 therefore extends substantially parallel to the vehicle windscreen during use. In essence it is important to ensure that the LED emitter is in a fixed positional relationship with respect the suction mount and cannot be varied intentionally or by accident.

[0136] The light source 21 is spaced a distance x away from the suction mount 22 along the support arm 23. In this example, the distance x is at least 10 cm. In a particular example, the distance x is 6 inches (15.24 cm). In use, the light source 21 is aligned above or below the damaged portion of the windscreen that needs to be repaired (i.e. the repair zone) (see FIG. 4). The spacing x ensures that the suction mount 22 does not apply stress to the repair zone, which improves the quality of the repair.

[0137] The curing unit 20 may be configured to be used to cure a windscreen repair resin according to any resin composition detailed above. For example, the curing unit 20 may be configured to cure a repair resin having the following composition: 30 to 80% wt acrylates; 4 to 25% wt acids; 0.5 to 10% wt oxysilanes; and 1 to 10% wt UV activated photoinitiator.

[0138] FIG. 4 shows the curing unit 20 of FIG. 3 positioned above a glazing panel 30 with the light source 21 turned on so that light 26 is emitted. The light source 21 is positioned a distance y above the exterior surface of the glazing panel 30.

[0139] The distance y is selected to ensure that the light 26 is emitted onto an exposure area on the glazing panel 30 that is sufficient to cover a repair zone 33. The optimum distance y depends on the properties of the light source 21.

[0140] The repair zone 33 is the area of the windscreen into which a resin is inserted to repair damage, such as crack or a break. Typically, this is less than 50 mm in diameter. Larger damaged areas or breaks usually necessitate replacement of the windscreen, rather than repair.

[0141] Alternatively, as shown in FIG. 5, the curing unit 10, 20 can be placed on the interior surface of the windscreen. In FIG. 5 the windscreen 30 has an exterior surface 31 and an interior surface 32. The interior surface 32 is the driver's side of the windscreen 30.

[0142] The degree of curvature of the windscreen 30 in FIG. 5 is for illustrative purposes only. The windscreen may be flat or of any degree of curvature.

[0143] A device 40 is secured on the exterior surface 31 of the windscreen over the repair zone 33. The device 40 is configured to (or to allow the user to) insert a resin into the repair zone 33 and apply pressure, or pressure cycling to the resin. For example, the device 40 may be of the type described in WO2015/040073 or EP1227927.

[0144] By mounting the device 40 and the curing unit 10, 20 on opposing sides of the windscreen both devices can communicate with the repair zone 33 simultaneously. This allows the resin to be cured whilst under pressure.

[0145] In other embodiments, the device 40 may be secured to the interior surface 32 of the windscreen and the curing unit 10, 20 may be secured to the exterior surface 31 of the windscreen.