APPLICATOR FOR THERMALLY ACTIVATING A FUNCTIONAL LAYER OF A COATING MATERIAL

Abstract

The present invention provides an applicator for thermally activating a functional layer of a coating material, comprising: a base body designed to guide the coating material in a running direction, wherein the base body is able to guide electromagnetic waves in the direction of the guided coating material, wherein a dielectric is arranged inside the base body and the dielectric is formed of granular material. The present invention also provides a device for thermally activating a coating material, a use of a dielectric, and a method for thermally activating a functional layer of a coating material.

Claims

1. An applicator (10) for thermally activating a functional layer of a coating material (8), comprising: a base body (13) designed to guide the coating material (8) in a running direction, wherein the base body (13) is able to guide electromagnetic waves (5), in particular microwaves, in the direction of the guided coating material (8), wherein a dielectric (14) is arranged inside the base body (13), and the dielectric (14) is formed at least in part of granular material.

2. The applicator (10) according to claim 1, wherein the dielectric (14) is arranged in such a way that the electromagnetic waves are guided through the dielectric (14) in the direction of the coating material (8).

3. The applicator (10) according to claim 1 or claim 2, wherein the dielectric (14) comprises ceramic and/or glass, preferably aluminum oxide (AL.sub.2O.sub.3) and/or quartz glass (SiO.sub.2).

4. The applicator (10) according to one of claims 1 to 3, wherein the applicator (10) is designed to be connected to a conductive means for electromagnetic waves, which is preferably configured in the form of a waveguide or a coaxial conductor, through which the electromagnetic waves (5) are fed into the applicator (10).

5. The applicator (10) according to one of claims 1 to 4, wherein the base body (13) guides the coating material (8) in such a way that the inside of the base body (13) is sealed off from the coating material (8), in particular by way of a solid portion of the dielectric and/or by guidance of the coating material in the applicator.

6. The applicator (10) according to one of claims 1 to 5, wherein the dielectric (14) has a dielectric loss factor of less than 510.sup.3 and preferably of less than 510.sup.4 and/or a permittivity greater than 1.5, preferably greater than 2, more preferably greater than 3 and even more preferably greater than 8.

7. The applicator (10) according to one of claims 1 to 6, wherein the granular dielectric is fixed by means of a dielectric which is not granular.

8. A device for thermally activating a coating material (8), comprising: a generator for generating electromagnetic waves (5), in particular microwaves, and an applicator (10) according to one of claims 1 to 6, which is able to apply the electromagnetic waves (5) generated in the generator to the coating material (8).

9. A use of a dielectric (14) in an applicator (10) for thermally activating a coating material (8) by means of electromagnetic waves (8), in particular microwaves, wherein the dielectric (14) is formed at least in part of granular material.

10. The use of a dielectric (14) according to claim 9, wherein the applicator (10) is an applicator according to one of claims 1 to 6.

11. A method for producing an applicator (10) for thermally activating a functional layer of a coating material (8) preferably according to one of claims 1 to 7, comprising the following steps: providing a base body (10), introducing a moldable, preferably granular, dielectric into the base body (10).

12. The method according to claim 11, comprising the following additional step: introducing a solid dielectric into the base body (10) for fixing the moldable dielectric therein.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG. 1 shows a sectional view of an example of an applicator as according to the prior art.

[0035] FIG. 2 shows a sectional view of a preferred embodiment of an applicator as according to the invention.

PREFERRED EMBODIMENTS OF THE PRESENT INVENTION

[0036] FIG. 2 shows a preferred embodiment of an applicator as according to the invention. The applicator 10 is intended to be connected to a generator (not shown) which generates electromagnetic waves. It is also intended that these electromagnetic waves thermally activate a functional layer of a coating material 8.

[0037] In this preferred embodiment, the electromagnetic waves are, in particular, microwaves in a frequency band of between 2.4 GHz and 2.5 GHz, but the frequency band of 5.725 GHz to 5.875 GHz is also conceivable here. This is provided as the ISM band (industrial, scientific and medical band) in the Radio Regulations of the Constitution and Convention of the International Telecommunications Union, an international treaty on the use of radio frequencies, and therefore also for such applications.

[0038] The applicator 10 firstly comprises a base body 13, which forms the structure of the applicator 10 and receives further elements thereof. Electromagnetic waves are received in the applicator via a conductive means (not shown) for electromagnetic waves and they are transferred therethrough to the coating material 8. The applicator 10 therefore serves as a resonator for electromagnetic waves. Waveguides and coaxial conductors can be used as conductive means for electromagnetic waves, wherein a waveguide usually refers to a metal pipe having a substantially rectangular, circular or elliptical cross-section and a coaxial conductor normally refers to a flexible conductor. In FIG. 2 the direction of propagation of the electromagnetic waves can be seen to be orthogonal to a feed direction of the coating material 8. The feed direction of the coating material 8 is in the cutting direction of FIG. 2. Furthermore, for guiding the coating material a seal can be provided, which encloses the coating material 8 and therefore seals off the inside of the applicator 10. In particular, there is therefore no direct transition between a region through which the coating material 8 runs and between other cavities of the applicator 10. Thus, when using the applicator 10 no impurities can reach these inner regions, which would entail lengthy and costly cleaning processes.

[0039] In the embodiment according to the invention as described herein, a part of the applicator is filled with a dielectric 14. As a consequence, the dimensions of the applicator can be reduced by a factor depending on the dielectric used. The dielectric 14 is formed at least in part of granular material. A core of the dielectric 14 consists of aluminum oxide powder (AL.sub.2O.sub.3). Sintered aluminum oxide has a permittivity of approximately 9.5, which is very high compared with other dielectrics such as Teflon (2.0), for example, or quartz glass (3.75). Non-sintered aluminum oxide, i.e. the aluminum oxide powder used in the embodiment shown herein, has a slightly lower permittivity. This depends primarily on the remaining amount of air in the aluminum oxide powder.

[0040] With the use of the dielectric 14, the size of the applicator 10 can therefore be reduced, which is illustrated in FIG. 2 with the dashed line 15. This line 15 relates to the applicator volume without the use of a dielectric, as shown for example in FIG. 1.

[0041] An alternative embodiment also provides for the use of quartz glass powder (SiO.sub.2) as the dielectric. As mentioned above, this has a slightly lower permittivity and can therefore be used when the reduction of the volume of space of the applicator is not a particularly high priority.

[0042] In the embodiment shown herein, the aluminum oxide powder is spatially fixed by means of quartz glass in solid form. For manufacture purposes, a first quartz glass cover, for example, can therefore first of all be used in the applicator 10. This is shown in FIG. 2 to the left of the dielectric 14 along the dashed line. This separates the internal cavity of the applicator into two parts. In a subsequent step, a granular dielectric is introduced into the open cavity on the right of the applicator. The granular dielectric can then be pressed using a die, for example, in order to reduce the air content in the granular dielectric. Subsequently, a second quartz glass cover can be used, which is located along the dashed line to the right of the dielectric 14. Thus, the granular dielectric is fixed between two quartz glass covers and can ensure the desired propagation of the electromagnetic waves 5.

[0043] In alternative embodiments, it is not absolutely essential to provide a granular dielectric between two covers of a solid dielectric. If, for example, a dielectric is provided to the left of the edge band 8 in the applicator 10 of FIG. 2, this can also be arranged on the left-hand edge of the applicator 10. Thus, the granular dielectric can be fixed by only one layer of solid dielectric.