Curtain applicator

Abstract

An applicator head for a curtain applicator for coating a continuous material web with liquid or pasty application medium. The applicator head has an outlet edge extending substantially over the width of the applicator head. The application medium passes out of the applicator head in a free-falling curtain. A rinsing device allows the outlet edge to be supplied with a flowing gaseous rinsing medium. There is also described a method for coating a continuous material web by way of such a curtain applicator. The application medium passes out of the applicator head in the form of a free-falling curtain and subsequently comes into contact with the material web. The region of at least one of the outlet edges can be supplied with a flowing gaseous rinsing medium.

Claims

1. A method for coating a continuous material web with a liquid and/or pasty application medium, the method comprising: providing at least one applicator head formed with at least one outlet edge that extends substantially over an entire width of the applicator head; providing a housing block having a transverse distribution chamber and a nozzle gap formed therein, and said housing block being surrounded at least in sections by an outer lining, where most of a front of said housing block, in a web movement direction, is surrounded by said outer lining and a thermally insulating layer that comes into contact with an exterior of the housing block; causing application medium to pass out of the applicator head in the form of a free-falling curtain and to subsequently come into contact with the material web; and selectively subjecting a region of at least one of the at least one outlet edges to a flowing gaseous rinsing medium; and at least partially forming the thermally insulating layer by a gaseous insulation medium at least partially provided by the flow of gaseous rinsing medium inside a gap between said housing block and said outer lining; and wherein the applicator head has an upper side and a lower side and said outlet opening is formed at said lower side, causing the rinsing medium that at least partially provides the insulation medium to flow downwardly to said outlet edge.

2. The method according to claim 1, which comprises maintaining a temperature of the rinsing medium between an ambient temperature and a temperature of the application medium, and/or maintaining the temperature of the rinsing medium in a range from 15° C. to 55° C., maintaining the temperature of the application medium in a range from 18° C. to 40° C., and wherein an ambient temperature is less than 65° C.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) The invention will be further explained in the following with reference to schematic drawings, which are not to scale. The drawings show the following:

(2) FIG. 1 shows a first embodiment of an applicator head according to the invention for generating a single-layer free-falling curtain,

(3) FIG. 1b shows a variant of the first embodiment of an applicator head according to the invention, for generating a single-layer free-falling curtain,

(4) FIG. 2 shows a second embodiment of an applicator head according to the invention for generating a single-layer free-falling curtain,

(5) FIG. 3 shows a third embodiment of an applicator head according to the invention for generating a single-layer free-falling curtain,

(6) FIG. 4 shows a fourth embodiment of an applicator head according to the invention for generating a single-layer free-falling curtain,

(7) FIG. 5 shows a fifth embodiment of an applicator head according to the invention, having a sliding surface for generating a single-layer free-falling curtain,

(8) FIG. 6 shows an embodiment of an applicator head according to the invention for producing a multilayer free-falling curtain, and

(9) FIG. 7 shows an embodiment of a curtain applicator according to the invention.

DESCRIPTION OF THE INVENTION

(10) FIG. 1 shows—in a cross-sectional view in a plane parallel to the web movement direction MD and perpendicular to the web transverse direction CD (CD extends perpendicular to the plane of the drawing in FIGS. 1-7)—a first embodiment of an applicator head 1 according to the invention for manufacturing a single-layer free-falling curtain 2 of a liquid and/or paste-like application medium for coating a continuous material web.

(11) The applicator head 1 has a transverse distribution chamber 3 and a nozzle gap 4 connected thereto, having the outlet opening 5, such that the application medium coming from the transverse distribution chamber 3 to the outlet opening 5 via the nozzle gap 4 exits the applicator head at the outlet opening 5.

(12) In the present case, viewed in the web movement direction MD, the outlet opening 5 provides a front outlet edge 6 and a rear outlet edge 7.

(13) As is apparent from the illustration in FIG. 1, the applicator head 1 comprises a first rinsing device and a second rinsing device 9 that are designed and arranged in such a way that, when the applicator head is in normal use, the first rinsing device 8 supplies the first outlet edge 6 from the front with a flowing rinsing medium 13 (dash-dotted line with arrow) and the second rinsing device 9 supplies the second outlet edge 7 from behind with a flowing rinsing medium 14 (dash-dotted line with arrow), as viewed in the movement direction of the material web. In the present exemplary embodiment, the two rinsing devices 8, 9 are both arranged outside of the nozzle gap 4. In the present case, each of the two rinsing devices provides a rinsing medium in the form of air.

(14) The applicator head 1 comprises a housing block made of a metallic material, in which the transverse distribution chamber 3 and the nozzle gap 4 are arranged. The housing block comprises a first housing block part 10 (front housing block part 10 in the present embodiment) and a second housing block part 11 (rear housing block part 11 in the present embodiment), and the transverse distribution chamber 3 and the nozzle gap 4 are formed by a cavity formed between the two housing block parts 10, 11. As illustrated in FIG. 1, the first housing block part 10 comprises a first nozzle lip 10.1, which the first outlet edge 6 provides in the region of the outlet opening 5 of the nozzle gap 4. In addition, the second housing block part 11 comprises a second nozzle lip 11.1, which provides the second outlet edge 7 in the region of the outlet opening 5 of the nozzle gap 4. The two nozzle lips 10.1 and 11.1 may be adjusted relative to one another in such a way that the width of the nozzle gap 4 in the region of the outlet opening 5 in the transverse direction of the applicator head may be individually adjusted.

(15) In the present exemplary embodiment, the housing block is surrounded in sections by an outer lining 12.1, 12.2, which comes into contact with the environment. The outer lining 12.1, 12.2 in this case has a front part, in the web movement direction MD, of the outer covering 12.1, in the form of a bent metal sheet; and a rear part of the outer covering 12.2, in the direction of web travel MD, in the form of a bent metal sheet. As may also be seen, the outer lining 12.1, 12.2 in the region of the outlet edges 6, 7 is arranged and designed in such a way that the free fall of the curtain 2 is not affected thereby.

(16) The outer lining 12 is thermally decoupled from the housing block 10, 11, at least in sections, by a thermally insulating layer.

(17) In the present case, the thermally insulating layer between the front part of the outer lining 12.1 and the front housing block part 10 is formed by a gaseous insulation medium that is fed in a gap between the front housing block part 10 and the front part of the outer lining 12.1, and is provided by the flowing gaseous rinsing medium 13 the first rinsing device 8.

(18) In addition, in the present case, the upper part of the gap between the rear housing block part 11 in FIG. 1 and the rear part of the outer lining 12.2 is formed by a foam material. It may further be seen that the lower part of the gap between the rear housing block part 11 and the rear part of the outer lining 12.2, which adjoins the upper part in FIG. 1, is formed by a gaseous insulation medium that is protected by the flowing gaseous rinsing medium 14, which is provided by the second rinsing device 9.

(19) In both cases, with regard to both the first rinsing device 8 and the second rinsing device 9, the rinsing medium flows toward the two outlet edges 6, 7 in a flow direction running from the upper side to the lower side.

(20) For the following discussion of FIGS. 1b and 2 to 6, it should be noted that only the differences from the respective explicitly-mentioned embodiment (for example the embodiment of FIG. 1) are discussed, and that the same or similar technical subject matter or features are designated by the same reference numerals.

(21) FIG. 1b shows a variant of the applicator head shown in FIG. 1. In this case, both of the rinsing devices 8, 9 are mounted in the lower region of the nozzle head. The upper part of the gap between the rear housing block part 11 and the rear part of the outer lining, 12.2, as well as the upper part of the gap between the front housing block part 10 and the front part of the outer lining, 12.1, is in this case completely or at least partially filled by a foam material.

(22) FIG. 2 shows a second embodiment of an applicator head 1 according to the invention for generating a single-layer free-falling curtain 2.

(23) The applicator head of FIG. 2 differs substantially from the applicator head shown in FIG. 1 in that in the applicator head of FIG. 2, both rinsing device 8, 9 are arranged in the lower region of the applicator head 1, i.e. at the level of the nozzle lips 10.1 and 11.1, and the outer lining 12.1 and 12.2 protrudes by up to 100 millimeters beyond the two outlet edges 6, 7 at the outlet opening 5 both in front and behind the curtain, in the direction of the free-falling curtain 2; and as a result, the free-falling curtain 2 is shielded from environmental disturbances such as air currents.

(24) In order to direct the flowing rinsing medium 13 provided by the first rinsing device 8 onto the first outlet edge 6, the front part of the outer lining 12.1 comprises a deflection plate 12.1.1. Analogously, the rear part of the outer lining 12.2 comprises a deflection plate 12.2.2, whereby the flowing rinsing medium 14 provided by the second rinsing device 9 is directed onto the second outlet edge 7.

(25) As a further difference from FIG. 1, the thermally insulating layer between the front part of the outer lining 12.1 and the housing block 10, 11, as well as between the rear part of the outer lining 12.2 and the housing block 10, 11, is respectively provided by air, which is not provided by the rinsing medium 13, 14. However, it may also be contemplated that instead of air, a different thermally insulating layer such as foam, mineral wool, etc. is used.

(26) FIG. 3 shows a third embodiment of an applicator head 1 according to the invention for generating a single-layer free-falling curtain 2.

(27) The applicator head 1 of FIG. 3 differs substantially from the applicator head shown in FIG. 1 in that the thermally insulating layer between the rear part of the outer covering 12.2 and the rear housing block part 11 is also formed by the gaseous insulation medium that is fed into the gap between the rear housing block part 11 and the rear part of the outer lining 12.2 is fed and is provided by the flowing gaseous rinsing medium 14 from the second rinsing device 9.

(28) FIG. 4 shows a fourth embodiment of an applicator head 1 according to the invention for generating a single-layer free-falling curtain 2.

(29) The applicator head 1 of FIG. 4 differs substantially from the applicator head shown in FIG. 3 in that no outer lining 12.1 and 12.2 is furnished.

(30) In the present exemplary embodiment, the housing block 10, 11 is surrounded only by the thermally insulating layer, which comes into contact with the environment, wherein the thermally insulating layer surrounding the front housing block part 10 is provided by the flowing gaseous rinsing medium 13 from the first rinsing device 8, and the thermally insulating layer that surrounds the rear housing block part 11 is provided by the flowing gaseous rinsing medium 14 from the second rinsing device 9.

(31) FIG. 5 shows a fifth embodiment of an applicator head 1 according to the invention for generating a single-layer free-falling curtain 2.

(32) The applicator head 1 of FIG. 5 has a transverse distribution chamber 3 and a nozzle gap 4 connected thereto, having an outlet opening 5 and an adjoining sliding surface 17, which in turn is adjoined by a outlet edge 16 in such a way that, viewed in the direction of flow of the application medium, the application medium that comes from the transverse distribution chamber 3 via the nozzle gap 4 and the outlet opening 5, flows past the outlet opening via the sliding surface 17 to the outlet edge 16 and then after passing the outlet opening 5, exits the applicator head 1 at the outlet edge 16. Notably, the sliding surface 17 is provided by a sliding surface block 15 arranged on the front housing block part 10.

(33) At the outlet edge 16, two rinsing devices 8, 9 are furnished, and by means of these, the flowing gaseous rinsing medium 13, 14 may be supplied by means of the outlet edge 16.

(34) FIG. 6 shows an embodiment of an applicator head 1 according to the invention for generating a multi-layer free-falling curtain 2′.

(35) The applicator head 1 of FIG. 6 differs substantially from the applicator head shown in FIG. 3 in that, in addition to a front and rear housing block part 10′, 11′, the housing block has a housing block middle part 18, and two transverse distribution chambers 3.1 and 3.2 that are respectively provided with a nozzle gap 4.1, 4.2 associated therewith, and these meet at the outlet opening 5 to generate a two-layer free-falling curtain 2 ‘. The supply to the two outlet edges 6, 7 and the thermal insulation of the housing block 10’, 11′, 18 is achieved analogously to the embodiment of FIG. 3, namely by supplying the first outlet edge 6 with the rinsing medium 13 provided by the first rinsing device 8 and supplying the second outlet edge 7 with the rinsing medium 14 provided by the second rinsing device 9, with the two rinsing media 13, 14 being fed respectively into the gap between the outer lining 12.1 and 12.2 in a flow direction running from the upper side to the lower side of the housing block 10 ‘, 11’, 18.

(36) FIG. 7 shows an embodiment of a curtain applicator 100 according to the invention for coating a continuous paper web with a liquid and/or paste-like application medium in the form of a free-falling curtain 2. By way of example, in the present exemplary embodiment, an applicator head as shown in FIG. 3 is used. Notably in this context, any other applicator head according to the invention could be used instead of the applicator head of FIG. 3.

(37) The curtain applicator 100 has rollers 102, 103 over which the paper web 101 is fed substantially horizontally during coating. The applicator head 1 and the point at which the free-falling curtain 2 meets the paper web 101 are shielded from environmental conditions by an enclosure 104 that is not air-conditioned.

(38) The curtain applicator 100 has means for adjusting the temperature of the rinsing medium 13, 14 and the application medium 2 in such a way that the temperature of the rinsing medium 13, 14 is between the ambient temperature and the temperature of the application medium 2.

(39) Specifically, these means comprise a temperature sensor 105 for measuring the temperature of the rinsing medium 13, 14 and a temperature sensor 106 for measuring the temperature of the application medium 2 in the region of the transverse distribution chamber 3. The means further comprise a heating and/or cooling device 107 for increasing and/or reducing the temperature of the rinsing medium 13, 14, and a heating and/or cooling device 108 for increasing and/or reducing the temperature of the application medium 2.

(40) As a further element, the means comprise a control and/or regulating device 110, by means of which the two heating and/or cooling devices 108, 109 are controlled and/or regulated automatically based on the measured temperatures of the rinsing medium 13, 14 and the application medium 2 and the set temperatures for the rinsing medium 13, 14 and the application medium 2. Specifically, by means of a control and regulation unit 110, in the event of deviations of the actual value from the set value of the temperature of the rinsing medium 13, 14 and the application medium 2, the respective temperature may be readjusted and/or controlled automatically by means of the respective associated heating and/or cooling device 107, 108.