Patent Application
20200407909
This application claims the priority, under 35 U.S.C. § 119, of German application DE 10 2019 117 281, filed Jun. 27, 2019; the prior application is herewith incorporated by reference in its entirety.
The present invention relates to a method for the production and/or processing of a nonwoven glass fabric web. The method includes the following step: thermal drying of a nonwoven glass fabric web by means of infrared radiation from an infrared radiation dryer. The present invention furthermore also relates to a corresponding device for carrying out the method.
In the processing of nonwoven glass fabrics, a coat is often applied thereon, in a similar way as is known when coating paper. In general, the subsequent drying of the coat is carried out by means of conventional air dryers, which function according to the impingement principle. However, since nonwoven glass fabrics have a high porosity, unlike paper, the blowing air can only be blown onto the nonwoven glass fabric surface coated with a low flow speed in order to avoid “blowing away” the coat. This consequently leads to low heat transfer coefficients and a low energy input. For the coat, this means slower immobilization.
The same applies for the production of nonwoven glass fabrics. The binder applied during production may likewise be “blown away” by excessively high air speeds, which leads to limitation of the specific energy input and therefore to slow immobilization, or delayed solidification of the nonwoven glass fabric.
In published, non-prosecuted German patent application DE 10 2016 120 933 A1 in the name of the Applicant, it has already been proposed to carry out the drying of the binder or coat for nonwoven glass fabrics at least partially by means of infrared radiation by means of an infrared radiation dryer. In this way, the risk of “blowing away” is reduced and immobilization of the coat, or solidification of the nonwoven glass fabric, may be carried out more rapidly.
A disadvantage with this known method is however that, as before, the immobilization of the coat, or the solidification of the nonwoven glass fabric, requires a certain time, which has a negative effect on the production quantity per unit time.
It is an object of the present invention to at least reduce the aforementioned disadvantage of the prior art.
This object is achieved by the features of the independent claims. The dependent claims relate to advantageous refinements of the invention.
Thus, the invention teaches a method for the production and/or processing of a nonwoven glass fabric web, which method contains the following step: thermal drying of the nonwoven glass fabric web by means of infrared radiation from an infrared radiation dryer, and which in particular is distinguished in that a specific power density of at least 153 kW/m2 is applied by the infrared radiation dryer to the surface of the nonwoven glass fabric web facing toward the infrared radiation dryer, and in that after the irradiation by the infrared radiation dryer, the nonwoven glass fabric web has a temperature of at least 40° C. and at most 105° C. on its surface facing toward the infrared radiation dryer.
The inventors have discovered that nonwoven glass fabrics unexpectedly withstand the application of such a high specific power density, which is at least 153 kW/m2, without damage, so long as it is ensured that the temperature at the surface remains in a moderate range of from 40° C. to 105° C. The high specific power density makes it possible to operate with high process speeds. The temperature at the surface of the nonwoven glass fabric web facing toward the infrared dryer depends crucially on the length of extent of the infrared radiation dryer in the process direction and on the speed with which the nonwoven glass fabric web is moved past the infrared radiation dryer relative to the latter. Both factors have an influence on the time for which a surface section of the nonwoven glass fabric web is exposed to the infrared radiation of the infrared radiation dryer.
If the nonwoven glass fabric web is intended to be processed by applying a coat, this is preferably applied onto the surface of the nonwoven glass fabric web facing toward the infrared radiation dryer immediately before the drying of the nonwoven glass fabric web by infrared radiation from the infrared radiation dryer. In this context, “immediately” means that no other machinery is intended to be provided between the application mechanism and the infrared radiation dryer. The path length between the application mechanism and the infrared radiation dryer may therefore be kept small, and the nonwoven glass fabric web coated with the coat may be guided freely, i.e. without contact, through the infrared radiation dryer. This is advantageous for the quality of the coat application, which must be protected against contact before it is fully dried. A curtain application mechanism is particularly suitable as an application mechanism for the coat.
After the drying of the nonwoven glass fabric web by means of infrared radiation from the infrared radiation dryer, the nonwoven glass fabric web may furthermore be dried by hot air in a hot air dryer. This may be economically advantageous since infrared radiation dryers generally have higher operating costs than hot air dryers. By the infrared radiation dryer, however, rapid immobilization of the coat or of the binder on the nonwoven glass fabric web may be achieved, so that the hot air dryer, which generally works according to the impingement principle, may be used for the subsequent full drying without running the risk of “blowing away” the applied coat or binder.
These two types of dryer may be operated together particularly economically if the infrared radiation dryer and the hot air dryer, which follows in the direction of movement of the nonwoven glass fabric web, are configured as a combination dryer unit. A plurality of such combination dryer units may also be arranged successively. In this case, hot air from the infrared radiation dryer is preferably aspirated and at least partially delivered to the hot air dryer. This makes the process particularly energy-efficient.
It is advantageous for there to be a distance of less than 50 cm, preferably less than 30 cm, between the hot air dryer and the infrared radiation dryer. In this way, it is possible to ensure that the temperature of the surface, irradiated by the infrared radiation dryer, of the nonwoven glass fabric web does not decrease significantly before the nonwoven glass fabric web is guided into the hot air dryer.
A further aspect of the present invention relates to a device for the production and/or processing of a nonwoven glass fabric web, wherein the device contains an infrared radiation dryer for thermal drying of the nonwoven glass fabric web by means of infrared radiation, which is distinguished particularly in that the infrared radiation dryer is configured to apply a specific power density of at least 153 kW/m2 to the surface of the nonwoven glass fabric web facing toward the infrared radiation dryer, and wherein the device is configured in such a way that after the irradiation by the infrared radiation dryer, the nonwoven glass fabric web has a temperature of at least 40° C. and at most 105° C. on its surface facing toward the infrared radiation dryer. Preferably, the device is configured to carry out the method according to the invention as described above.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method for the production and/or processing of a nonwoven glass fabric web, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
Referring now to the figures of the drawings in detail and first, particularly to
The dryer 10 contains an infrared radiation dryer 20 arranged upstream as seen in the process direction, and a hot air dryer 30 arranged downstream. The distance A between the infrared radiation dryer 20 and the hot air dryer 30 is in this case less than 30 cm. The infrared radiation dryer 20 may itself contains a plurality of modules, of which each module may in turn contain a plurality of rows of individual infrared radiators. In the exemplary embodiment represented here, the infrared radiation dryer contains two modules 21, 22, each of which contains two rows of infrared radiators. Furthermore, each of the two modules 21, 22 also contains a fresh air supply and a used air discharge, the air flows being denoted by arrows in
According to the invention, a specific power density of at least 153 kW/m2 is applied by the infrared radiation dryer 20 to the surface of the nonwoven glass fabric web G facing toward the infrared radiation dryer. At the same time, by suitable selection of the overall length of the infrared radiation dryer 20 and of the speed with which the nonwoven glass fabric web G is guided through the dryer 10, it is ensured that, after the irradiation by the infrared radiation dryer 20, the nonwoven glass fabric web has a temperature of at least 40° C. and at most 105° C. on its surface facing toward the infrared radiation dryer 20. In order to monitor the surface temperature, a temperature sensor T which is suitable for contactlessly determining the temperature on the surface of the nonwoven glass fabric web at the end of the infrared radiation dryer 20, for example by use of laser technology, may be installed in the dryer 10.
The hot air dryer 30 is configured to blow hot air, which it draws from a source (not represented here), onto the surface to be dried of the nonwoven glass fabric web G. In this case, the drying is carried out primarily by the impingement principle.
The second exemplary embodiment of a device according to the invention, represented in
| Number | Date | Country | Kind |
|---|---|---|---|
| 102019117281 | Jun 2019 | DE | national |
