AU2008303518A1

AU2008303518A1 - Portable ultraviolet and visible light lamp

Info

Publication number: AU2008303518A1
Application number: AU2008303518A
Authority: AU
Inventors: Huig Klinkenberg; Maarten Van Pul
Original assignee: Akzo Nobel Coatings International BV
Current assignee: Akzo Nobel Coatings International BV
Priority date: 2007-09-28
Filing date: 2008-09-25
Publication date: 2009-04-02
Anticipated expiration: 2028-09-25
Also published as: WO2009040387A2; RU2010116692A; RU2473837C2; JP2011502031A; WO2009040387A3; KR20100075554A; BRPI0815997A2; CN101808752A; EP2209563A2

Description

WO 2009/040387 PCT/EP2008/062809 Portable Ultraviolet and Visible Light Lamp The invention relates to a portable ultraviolet and visible light (UVIVIS) lamp 5 having a plurality of UVIVIS light emitting diodes (UVIVIS-LEDs) as UVIVIS radiation source. The invention further relates to a process of preparing a cured coating. Hand-held portable UVIVIS-LED lamps are commercially available, for example 10 from Panacol-Elosol GmbH in Germany or from Clearstone Technologies Inc. in the United States of America. Movable UVNIS lamps for curing surface coated materials are described in International Patent Application WO 2006/047866 A. This document describes UVIVIS radiation sources mounted on a positioning panel supported by a stand. Fluorescent lamps, LEDs, electron beams, and 15 lasers are mentioned as suitable radiation sources. In connection with fluorescent lamps, air cooling by a blower, fan or pressurized air is mentioned. A drawback of the known hand-help UVIVIS-LED lamps is the limited UVIVIS light intensity they generate, as well as the limited area covered by the UVIVIS 20 radiation. UVIVIS-LEDs are characterized by a more efficient conversion of electric energy into UVIVIS radiation than traditional UVIVIS radiation sources, such as fluorescent lamps, or metal halide lamps. However, also in UVIVIS LEDs a significant proportion of the electric energy is transformed into heat. In addition, the maximum operating temperature of LED is generally lower, about 25 1200C, than the operating temperature of conventional UV lamps. The durability of UVIVIS-LEDs decreases when they are operated at too high temperature. Therefore, increasing the UVNIS light intensity and the area covered by UVIVIS generation by using a higher number of individual UVIVIS LEDs leads to the problem of increased operating temperature of the UVIVIS 30 LEDs. Therefore, cooling means are required in order to prevent overheating of the UVIVIS-LED lamp. However, cooling means such as blowers or fans WO 2009/040387 PCT/EP2008/062809 2 generally add to the complexity, weight, and size of a portable UVIVIS-LED device. The present invention seeks to alleviate the above-mentioned problems. More in particular, the invention seeks to provide a portable UVIVIS-LED lamp 5 capable of generating high intensity UVIVIS radiation and having simple, small and light weight cooling means. The invention now provides a portable ultraviolet (UVVIS) lamp having a UVIVIS-light emitting diode (UVIVIS-LED) unit comprising a plurality of UVIVIS 10 LEDs as UVIVIS radiation source, a UVIVIS-LED electric power supply, and a cooling medium feed line connectable to a cooling medium reservoir for providing a flow of cooling medium to the UVIVIS-LEDs. The use of UVIVIS-LEDs has several advantages over conventional sources of 15 UVIVIS radiation. UVIVIS-LEDs allow instant on/off switching of the UVIVIS radiation source, which adds flexibility. Furthermore, the service life of UVIVIS LEDs generally is significantly longer than the service life of conventional UVIVIS sources, for example up to 50,000 hours for a UVIVIS-LED compared to about 1,000 hours for conventional UVNIS lamps. Further, UVIVIS-LEDs 20 generally have a narrow wavelength distribution and offer the possibility to customize the peak wavelength. The peak wavelength of the UVIVIS-LEDs suitable is between 200 nm and 500 nm. When pure UV light is required, the peak wavelength suitably is between 200 and 400 nm. In order to reduce the health risks associated with skin and eye exposure to UV radiation, it may be 25 preferable to use UV-LEDs having a peak wavelength in the range of 320 to 400 nm. However, it is also possible to use UVNIS-LEDs having a peak wavelength in the wavelength range of visible light, such as 400 nm to 500 nm. Another advantage of UVIVIS-LEDs is their relatively low working voltage, which is preferred in a paint spray booth environment compared to the higher 30 voltages needed for normal UVIVIS lamps. The plurality of UVIVIS-LEDs of the lamp can suitably be grouped together in a so-called UVIVIS-LED array. The number of individual UVIVIS-LEDs in a WO 2009/040387 PCT/EP2008/062809 3 UVIVIS-LED array can be customized depending on the required size, shape, and UVVIS radiation output required. A UVIVIS-LED array can for example comprise 10 to 50, or several hundreds or even thousands of individual UVIVIS LEDs. 5 The shape of the UVIVIS-LED array is not critical. It may be of any suitable shape. As an example, a circular UVIVIS-LED array to be placed around the nozzle of a paint spray gun may be mentioned. The UVIVIS-LED electric power supply can be a battery pack. In one 10 embodiment, the batteries are rechargeable. It is also possible to use a power supply connected to the electric power grid. The cooling medium feed line is connected to the UVIVIS lamp so as to provide a flow of cooling medium to the UVIVIS-LEDs. The cooling medium feed line 15 suitably is made of a flexible material, for example rubber or plastic, which may optionally be reinforced with fibers or wires. The cooling medium feed line can be permanently attached to the UVNIS lamp. Alternatively, the cooling medium feed line can be releasably attached to the UVIVIS lamp, for example by a bayonet-type fitting. 20 The cooling medium feed line is connectable to a cooling medium reservoir. In operation, the cooling medium feed line is connected to the cooling medium reservoir. Cooling medium will then flow from the reservoir to the UVIVIS-LEDs in order to cool them. The cooling medium can be a liquid cooling medium or it can be a gas, in particular a compressed gas. An example of a suitable liquid 25 cooling medium is water. An example of a gaseous cooling medium is compressed air. Compressed air is particularly suitable as cooling medium when the UVIVIS lamp is used for UVIVIS curing of paint, because compressed air reservoirs are present anyway in many paint spray shops. When air or a similar non-toxic gas or gas mixture is used a cooling medium, 30 the cooling medium can be discharged directly into the environment without any negative consequences. In a further embodiment, the UVIVIS lamp additionally comprises a cooling medium discharge line for discharge of the cooling WO 2009/040387 PCT/EP2008/062809 4 medium. Depending on the type of cooling medium used, the cooling medium can be disposed off through the cooling medium discharge line or it can be recycled to the cooling medium reservoir. The portable UVIVIS lamp suitably is a hand-held device. The UVIVIS lamp can 5 be used as such as hand-held UVIVIS lamp. In another embodiment, the UVIVIS lamp can be part of a paint spray gun, for example such as described in International Patent Application W02004/069427. The UVIVIS lamp can be permanently attached to the paint spray gun. In another embodiment, the UVIVIS lamp has means for releasably attaching the UVIVIS lamp to a paint 10 spray gun. In this case the UVIVIS lamp can be used as such or attached to a paint spray gun. It is also possible to releasably combine the UVIVIS lamp with a specific holder to allow easy manipulation of the UVIVIS lamp. In one embodiment, the cooling medium stream path comprises a valve for 15 control of cooling medium flow. The cooling medium stream path includes the cooling medium feed line, the interior of the UVIVIS-LED unit, and the optional cooling medium discharge line. The UVIVIS-LED power supply switch is preferably implemented in such a way that the power supply can only be switched on when the valve in the cooling medium stream path is open. This 20 can for example be achieved by physically coupling the trigger for opening the valve and the button for actuating the electrical switch of the power supply. In a further embodiment, the cooling medium stream path comprises a valve for control of cooling medium flow and a sensor to detect the flow of cooling medium. The UVIVIS-LED power supply can be switched on or off as a function 25 of flow of cooling medium detected by the sensor. It should be noted that the term flow sensor includes embodiments wherein flow is detected by pressure differences sensed by one or more pressure sensors. When the flow in the cooling medium stream path exceeds a predetermined value, the sensor can cause the UVIVIS-LED power supply to be switched on. When the detected flow 30 is below a predetermined value, the sensor can cause the UVIVIS-LED power supply to be switched off. In a simplified embodiment, the predetermined flow value can be 0 I/min. In that case, the device is switched on when the flow of WO 2009/040387 PCT/EP2008/062809 5 cooling medium exceeds 0 1/min and the device is switched off when there is no flow of cooling medium. The flow of cooling medium is generally actuated by the user, for example by pulling a trigger to open the valve in the cooling medium stream path, for example in the feed line. Upon flow of the cooling medium, the 5 UVVIS-LED power supply and accordingly the UVVIS-LEDs will be switched on, and they will be switched off when the flow of cooling medium stops, for example when the trigger is released. In such an embodiment it is assured that UV/VIS-LEDs will only be switched on if there is sufficient flow of cooling medium. Therefore, overheating of the UVVIS-LEDs can be safely excluded. 10 Portable UVVIS lamps are frequently used for curing UVVIS-curable coatings and adhesives. Coating and adhesive materials often contain volatile organic compounds, such as solvents and/or monomers, which evaporate during and/or after application to a substrate. This can lead to an explosive atmosphere in the vicinity of the coated substrate. Therefore, curing with UVVIS lamps which are 15 not explosion-proof can only be started after an aeration period sufficient to remove the volatile organic compounds. This brings about a delay in the entire process and can have a negative impact on the economy of the coating process. It should be noted that UVNIS curing processes are frequently very fast. As a consequence, the above-mentioned aeration phase may become the 20 bottleneck for optimizing the process speed for coating and UVVIS curing. Therefore, there is a need in the coating and adhesive industry for a portable UVVIS lamp which can safely be used immediately after application of a coating or adhesive layer in an explosive environment. The portable UVVIS lamp of the invention can be easily adapted for safe use in 25 an explosive environment. This can be greatly facilitated by spatially separating the UVVIS-LED power supply and the sensor for detecting the flow of cooling medium from the UVNIS-LED unit. The sensor to detect the flow of cooling medium and the UVVIS-LED electric power supply are suitably located in an area with a non-explosive atmosphere. The UVVIS-LED unit cannot trigger an 30 explosion during normal operation, because all electrical parts which could trigger an ignition or explosion can be located outside the area of explosive atmosphere. Additional measures can be taken to minimize explosion risk in WO 2009/040387 PCT/EP2008/062809 6 case of likely failures, such as mechanical damage. An example of such an additional measure is creating and automatically monitoring overpressure in the LED chamber. Upon failure of the overpressure, the device is automatically switched off. A mechanical trigger to open the valve in the cooling medium feed 5 or discharge line can be located close to the UVIVIS-LED unit. In such an embodiment, the UVIVIS-LED lamp can be switched on or off by an operator actuating the mechanical trigger in the vicinity of the UVIVIS-LED unit. Pulling the mechanical trigger in the explosive atmosphere opens the valve in the cooling medium feed or discharge line. This starts the flow of cooling medium 10 which is detected by the flow sensor outside the explosive environment. In response to detected flow, the flow sensor causes the UVIVIS-LED power supply, which is also located outside the explosive environment, to be switched on. 15 The UVIVIS lamp of the invention can be used for all purposes where UVIVIS radiation is required. The UVIVIS lamp is particularly suitable for curing UVIVIS radiation-curable coatings and adhesives. Therefore, the invention also relates to a process of preparing a cured coating comprising applying a UVIVIS-curable coating composition to a substrate and curing the coating by irradiation with 20 UVIVIS-radiation, wherein the UVIVIS radiation is provided by the portable UVIVIS lamp according to the invention. The substrate can for example be an automobile or a large transportation vehicle, such as a train, bus, truck, or aircraft. The process can also be implemented for repair coating of automobiles and transportation vehicles. The process is particularly suitable for repair 25 purposes wherein only a part of the substrate, for example an individual body panel or a damaged spot, is provided with a repair coating.

Claims

1. A portable ultraviolet/visible light (UVIVIS) lamp having a UVIVIS-light emitting diode (UVIVIS-LED) unit comprising a plurality of UVIVIS-LEDs 5 as UVIVIS radiation source, a UVIVIS-LED electric power supply, and a cooling medium feed line connectable to a cooling medium reservoir for providing a flow of cooling medium to the UVIVIS-LEDs.

2. The portable UVNIS lamp according to claim 1, wherein the UVNIS lamp additionally comprises a cooling medium discharge line. 10

3. The portable UVIVIS lamp according to any one of the preceding claims, wherein the cooling medium stream path comprises a valve for control of the flow of cooling medium and a sensor to detect the flow of cooling medium, and wherein the UVNIS-LED power supply can be switched on or off as a function of flow of cooling medium detected by the sensor. 15

4. The portable UVIVIS lamp according to any one of the preceding claims, wherein the UVIVIS lamp is a hand-held UVIVIS lamp.

5. The portable UVIVIS lamp according to any one of the preceding claims, wherein the UVIVIS lamp is part of a paint spray gun.

6. The portable UVIVIS lamp according to any one of the preceding claims, 20 wherein the UVIVIS lamp has means for removable attachment of the lamp to a paint spray gun or to a holder.

7. The portable UVIVIS lamp according to any one of the preceding claims, wherein the cooling medium feed line is connected to a cooling medium reservoir containing a compressed gas. 25

8. The portable UVIVIS lamp according to claim 7, wherein the compressed gas is compressed air.

9. The portable UVIVIS lamp according to claim 3, wherein the UVIVIS lamp is adapted for operation in an explosive atmosphere. 1O.The portable UVIVIS lamp according to claim 9, wherein the sensor to 30 detect the flow of cooling medium and the UVIVIS-LED electric power supply are spatially separated from the UVIVIS-LED unit.

WO 2009/040387 PCT/EP2008/062809 8

11.The portable UVIVIS lamp according to claim 10, wherein the sensor to detect the flow of cooling medium and the UVNIS-LED electric power supply are located in an area with a non-explosive atmosphere.

12.A process of preparing a cured coating comprising applying a UVIVIS 5 curable coating composition to a substrate and curing the coating by irradiation with UVIVIS-radiation, wherein the UVIVIS radiation is provided by the portable UVIVIS lamp according to any one of the preceding claims.

13.A process according to claim 12, wherein the substrate is an automobile 10 or a large transportation vehicle.