Drying and gas or vapor contact with solids – Apparatus – Combined
Reexamination Certificate
2002-01-04
2003-12-02
Lazarus, Ira S. (Department: 3749)
Drying and gas or vapor contact with solids
Apparatus
Combined
C034S275000, C034S266000, C034S278000, C034S245000, C034S277000, C392S416000, C219S757000, C250S50400H, C250S495100
Reexamination Certificate
active
06655040
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION(S)
None.
BACKGROUND OF THE INVENTION
The present invention relates to infrared drying units and more particularly relates to an infrared drying system having an incorporated ultraviolet curing unit.
In the art of printing and coating, liquid substances are applied to sheets and webs of material such as paper, film, and foil. These substances, when manufactured appropriately and solidified, are used to impart various surface properties to the material. Such surface properties include defined patterns of color, through a process of printing, scuff resistance, through a process of clear coating, or stickiness, through a process of applying an adhesive coating. These liquid substances are designed specifically for solidification by one of several methods.
One of the most commonly used methods of solidification is evaporation of the liquid portion of the substance through exposure to a combination of air movement and electrically generated infrared energy. When using air movement and infrared energy, the liquid substance used must be an evaporative coating. The machines used to evaporate such coatings are referred to as infrared dryers (IR dryers). Another method of solidification is polymerization of the liquid substance through exposure to specific wavelengths of electrically generated ultraviolet light. Such liquid substances are called ultraviolet coatings, and the machines used to polymerize such coatings are referred to as ultraviolet curing units (UV curing units).
In general, users of printing and coating machinery have found that evaporative coatings and ultraviolet coatings, and their associated methods of solidification, each have advantages and disadvantages. For example, evaporative coatings are generally less expensive than ultraviolet coatings, but the UV curing units used to solidify ultraviolet coatings generally require less space than the IR dryers used to dry evaporative coatings. These and other considerations dictate whether the user, when printing or coating a particular product, should apply evaporative coatings or ultraviolet coatings.
It is not possible to use IR dryers and UV curing units interchangeably. Because the solidification of ultraviolet coatings requires specific wavelengths of ultraviolet energy, infrared energy cannot be used for solidification of ultraviolet coatings due to infrared energy occupying an entirely different portion of the electromagnetic spectrum. Furthermore, although ultra-violet light sources currently in use generally produce significant amounts of infrared energy in addition to ultraviolet energy, the economics of shorter bulb life and higher power consumption have dictated that a separate infrared source should be used when drying evaporative coatings. Therefore, users of printing and coating equipment who want to have the most flexibility in printing or coating find it necessary to purchase and install both IR drying and UV curing equipment.
Modern drying and curing equipment frequently uses applied power densities in the range of 40 to 100 watts per square inch or higher. At such power densities, efficient and safe operation requires that the equipment be equipped with cooling systems. Electric IR dryers are commonly equipped with moving air cooling systems or water cooling systems to cool the heat emitting elements, electrical connections, and element supports. With either air or water cooling methods, it has been found that the addition of air directed against the substrate and coating enhances the drying by transferring liquid vapor from the substrate and coating to the air. Rather than permit the heated air used for cooling and vapor removal to blow into an area where machine operators are performing their work tasks, an air exhaust system is typically incorporated into the IR drying equipment to remove the heat and vapor laden air and convey it to a controlled destination.
Similar to IR dyers, UV curing equipment is commonly equipped with air or water cooling systems to carry away a portion of the large quantity of heat created by the operation of the ultraviolet energy source used in these systems. When air is used for cooling, the resulting heated air is generally exhausted from the ultraviolet equipment and conveyed to a controlled destination in such a way that it does not contact and heat the substrate unnecessarily. This is additionally beneficial because it prevents the heated air from contacting the UV lamp. As is commonly known by experienced ultraviolet equipment designers, potentially hazardous levels of ozone are formed in quantities proportional to the amount of cooling air which contacts the lamp.
Though it is possible to combine a UV curing unit with an IR dryer, challenges arise which have thus far prevented a successful combination system. In particular, designing a cooling system for use in such a combination system has proven particularly difficult. As a result, IR drying equipment and UV curing equipment are commonly designed and built as separate units, each having its own set of cooling systems. To allow for printing a variety of applications, a facility must have both an IR dryer and a UV curing unit. Requiring both such systems increases costs and occupies more floor space.
Thus, there is a need in the art for an IR drying system capable of incorporating UV curing equipment without compromising the performance of either the IR drying unit or the UV curing unit.
BRIEF SUMMARY OF THE INVENTION
The present invention is a combination UV curing and IR drying system. The combination system comprises both an IR dryer module and a UV curing unit. To allow both the IR dryer module and the UV curing unit to operate at the same time, a cooling system is used to cool the modules. The cooling system comprises an air supply for supplying air to the UV curing unit and IR dryer module. The air passes through the UV curing unit and IR dryer module, cooling the units as necessary. Once the air exits the UV curing unit and IR dryer module, the now warm air is exhausted from the system using an air exhaust system.
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Kinney & Lange PA
Lazarus Ira S.
Nguyen Tu Cam
The Diagnostics Group, Inc.
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