FI108848B - Method and apparatus for coating a fibrous web - Google Patents

Abstract

To apply a coating to a fibre web, and esp. paper, the coating is applied as an initial dosing directly to an applicator roller through at least one free spray stream. Pref. the free jet stream (13) is applied directly at the mantle surface (11, 12) of the applicator roller (1, 2), or at the surface of a transfer roller which carries the coating to the applicators (1, 2). The free jet stream (13) and/or its application angle can be adjusted.

Description

108848

Method and apparatus for coating a fiber web -Förfar-ande och anordning för ytbeläggning av en fiberämnesbana I 5

The invention relates to a method according to the preamble of claim 1 for one-sided coating of a fiber web with a coating material and further for an apparatus for performing the procedure.

10

Various methods and devices are known in the paper converting industry for coating a fiber web with a coating material. Thereby, the fiber web coating material is coated either by directly applying it to the fiber web which partially surrounds the rotationally symmetrical body or by pre-dispensing the rotationally symmetrical body onto the surface of the casing. In each case, the application takes place in two successive steps, which are the application of excess coating or adhesive mass on the application nozzle and the associated equalization of excess coating mass by means of mostly subsequent blade or blade devices. In the latter case, the transfer takes place, for example, in a film press. In conventional film presses, the coating material is applied to the surfaces of the coating rolls, whereby smoothing is effected by means of regularly arranged squeegee devices.

The preloaders are located within the frames of the coating rolls and can be pressed against the coating rolls and cylinders of the coating rolls or the like. The pre-dispensing device 30 comprises a nozzle applicator, from which a glue or pin (; kneading ink) is introduced into a pressure nozzle pressure chamber by a special dispensing system and a coating device. The coating 1 'enters the pressure chamber through a slot nozzle into a dispensing space.

/ * · The amount of adhesive or coating mass is controlled by a roller squeegee, ••, 35 or a press against the blade.

t »2 108848 The drawback of such structures is, first and foremost, the complex construction of the application or dispensing system and the use of the wear part as the dispensing element, which makes keeping the film thickness constant from time to time very problematic and not directly affected. Also, the transverse profile of the applied material can be kept constant only by long-term profile adjusting operations, i. machine application may not be uniform. Furthermore, at high solids contents or in the case of highly absorbent paper 10, there is a risk of forming grooves, which results in a limitation on the minimum amount of coating. The use of a wear part as a metering element results in too short metering element lifetimes and thus unwanted machine downtime forced by the metering element change. Furthermore, controlling the amount of coating without changing the metering element is hardly possible.

Thus, it is an object of the invention to further develop a method and apparatus for performing the procedure as described above, so as to avoid said drawbacks. The amount of film to be transferred to the fiber web must be kept constant. . kion all the time and across the machine width, i.e. perpendicular to the direction of travel of the fiber web. Number of film to be applied 25 "; ' In addition, the method or apparatus to be further developed will be subject to the essential requirements, in particular, to minimize wear on the metering elements and thus to achieve longer operating times between required metering exchanges: Other: · lower operating costs and suitability for use with coating paints and adhesives.

The metering element should be support-3,.,:, And of low vulnerability to high-spreading. * ··. easy to use, and have only a very small number of consumables.

3 108848!

The solution according to the invention is characterized in the characterizing part of claim 1. The essential features of the device according to the invention are apparent from claim 3. In addition, there is the possibility of solving the problem with the device according to claim 13. Advantageous design possibilities are disclosed in the dependent claims.

Pre-dosing according to the invention takes place by means of a two-element applicator on the coating roll casing at least indirectly, i. both directly and indirectly by application of the coating agent in at least one free jet. The use of a free jet provides the advantage of certain parameters such as the outlet cross-section, the exit speed and the free jet jet! with a roll angle with respect to the speed of rotation of the coating roll, 15 possibilities for direct control of the coating amount and thus the thickness of the film to be applied on the surface of the casing.

The free jet may be directed directly to the surface of the coating roll sheath or to the surface of the transfer roll sheath which, in turn, will transfer the coating material at least indirectly, i. directly or through another transfer roll to the surface of the coating roll cover. The latter variant (indirect application) further offers the advantage of another dosing effect, in particular the stretching roller of the coating film and the transfer | .., 'j25 by the difference in velocity of the coating surfaces of the coating and transfer rolls obtained by determining the diameter ratios of the roll.

• I I I

The device according to the invention is defined in the characterizing part of claim 3. A two-element coating device (at least one coating element is placed on the i30 tea, · · ... preferably a spreading roll, a coating unit comprising *; · 'a device for generating a free jet which at least indirectly spreads the exterior of the coating agent spreading element - *,' The free-jet generating device may then be positioned directly on the coating element (free jet is directed directly to the outer surface of the coating element), or moved thereto by means of at least one transfer element 4 108848.

The two-element coating apparatus is best designed as a two-roll coating apparatus, i. two coating rolls of 5 axes parallel to each other are used in counter movement and form a compression gap through which the fiber web is guided. Application of the coating agent to the fiber web is effected by passing through a compression slot, whereby a predetermined amount of coating on the outer surface of the coating roll is transferred to the fiber web. This device is suitable for coating both the fiber webs and the single-sided as well as the double-sided coating material, whereby both sides of the fiber web can be coated with the same or different coating materials. According to the invention, two possibilities are conceivable: 1) the application is carried out immediately, i. directly on the surface of the coating roll sheath; 2) application is carried out indirectly or indirectly, i. on the surface of the sheath of the transfer roll provided on the coating roll.

20

Another possibility provides an advantage in the construction of diameter ratios between the coating and transfer rolls to obtain the additional effect of dosing, which is regularly in the form of stretching on the film screen roll. It is particularly advantageous when a particularly thin coating film for a fiber web is desired.

M: The design of the free jet device consists of two f, · · preferred options: 30: 1) a free jet nozzle, 2) a closed mass feed with a pressurized central reservoir and a variable adjustable outlet.

The free jet nozzle device may then be constructed as described in U.S. Patent Nos. 3,418,970, 3,531,602 and 4,231,318. The free-jet nozzle device is regularly a coating device with a support piece comprising, for example, a divider and a slot nozzle extending over the entire machine width. The application is effected without contact of the nozzle with the surface of the cover 5 of the coating element. The free jet nozzle device is displaceable radially with respect to the surface of the coating roll shell and pivoting about a given axis so that the application angle is adjustable with respect to the surface of the coating roll shell. The nozzle device is best positioned in accordance with US 3 418 970 with respect to the surface of the coating roll 10, so that the coating direction, i. a narrowing gap is formed between the surface of the coating or transfer roll shell and the free jet nozzle in the direction of rotation of the roll.

In addition to this, the nozzle channel of the nozzle device, i. the connecting pipe between the distributor and the outlet of the nozzle to be curved. The curvature passes substantially tapering to the coating or transfer roll. This procedure then has a low-air layer against the roll and a high-air layer 20 outside.

The dosing effect of the system during coating is determined by various factors. These include: • · 25 "; 1) flow or outlet cross section of free jet nozzle or pulp feed tank; 2) coating material outlet rate; i.i ί 3) distributor or container pressure; 4) top roller rotation speed.

30

The change in the revolution of the outlet cross-section and the revolution of the coating or transfer rolls is simple to implement, while the changes in the exit velocity as a function of the exit cross-section and the structure of the nozzle or reservoir.

According to a further aspect, the two-element coating device 6108848 may comprise a coating roll which, with the rotating belt, forms an extended compression slot for passing through the fiber web. Free jet application is then best applied to the surface of the coating roll cover, but | It is also conceivable, under certain conditions, to apply to the belt. Such a device is also suitable for single-sided and double-sided coating of fiber webs.

Devices for generating a free jet are preferably located on that part of the surface of the coating or transfer roll shell which is in the area of rotation of the roll prior to the entry into the compression slot. It is also conceivable to locate areas further away from the entrance of the compression slot. In this case, for example, the use of additional smoothing devices, for example in the form of air brushes, is best used for leveling the applied film.

The free jet application of the invention to the outer surface of the coating insert provides the advantage of direct control of the coating material to the outer surface of the coating element, and thus the pre-dosing of the amount of coating to be transferred to the compression slot. The system of the invention provides additional. . the advantage that the amount of film to be coated can be kept constant, over and over the entire working width. Coating or 25 * ··· 'dispensing systems le is characterized by a small number of wearing parts »t · d and thus longer operating times between the necessary changes of the dispensing elements. Adjusting the outlet opening! | J and its position relative to the coating element are iT: easy to implement structurally The procedure of the invention is suitable for both coating mass and starch.

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With respect to coating by open pulp feed, in order to obtain the desired direct effect on dosage, additional measures. Additional throttling or other interference elements at the outlet of the open container, ···, are contemplated.

7 108848

The solution according to the invention according to the present invention is explained below in connection with the figures. 1 depicts a two-roll coating apparatus with a free jet nozzle mounted on a coating roll thereon and a STDA with a coil on a second coating roll; Figure 2 is a two-roll coating device with a free jet nozzle located therein and an additional leveling system; Fig. 3 is a two-roll coating machine with a transfer roll; Fig. 4 is a two-roll coating apparatus provided with a closed pulp feed to a coating roll and an open pulp feed to a second coating roll; 15 and Fig. 5 are a two-element coating apparatus comprising a roller and a belt with a free jet nozzle.

Figure 1 illustrates a two-roll coating apparatus. Coating roller 1 and coating roller 2, which are parallel to their axes and rolled together, form a roll slot 3 for passing through a fiber web, in particular a paper web 4. Each of the * * * tank coating rolls is used in relation to each other. direction. A coating unit 5, 6 is disposed underneath the substantially revolving part of the rolls of each roll 1, 2 for a fluid.

;, · · The fiber web is guided through the roll slot 3 from the bottom up. For example, a film of fluid flows from areas 7, 8 which form a web slot 3 with the fiber web 30 through the outer surfaces of the rolls, to one side of the web 4. By guiding the fiber web 4 through the roll slot 3 * * i from below upwards, a coating material, for example a coating mass, is applied between the peripheries of each roll 1 and 2 3cl> #>! at a distance corresponding to the desired thickness of the fiber web 4.

i · Coating devices 5 are made as free jet nozzle devices. The nozzle channel of the free jet nozzle device 5 is made i> 8 108848 best curved. The free shower 13 is illustrated schematically, respectively. The coating device 6 is made in the form of a STDA with a squeegee, for example as in unpublished patent DE 42 30 276. The coating mass is applied to the surfaces of the diapers 11 or 12 of the rolls 1 and 2, respectively.

Fig. 2 illustrates a structure similar to Fig. 1, in which a leveling device is also located. The same elements are therefore denoted by the same reference numerals. Here, however, the fuel web 4 is guided from the top through the press gap 3. A roller unit 5a or 5b, respectively, is provided in the lower portion of the bottom of each roller 1, 2 of the roller, or of the roller casing 11, 12 for the coating material, for example, for coating colors. The fibrous web 4 15 is passed through a roll slot 3 from top to bottom. In this case, a film of fluid is applied to the fiber web in the areas 7, 8 forming the roll slot by means of the outer surfaces 11 or 12 of the rolls. Further, relative to the application means 5a, 5b, air-brush leveling devices 14 and 15 are disposed in the post-rotation portion of the roll casings 11, 12 in the form of airbrushes. The air jets thus produced affect the leveling of the applied coating mass. . transfer to a fiber web 4 via a roll slot 3.

* · * Rt * il * * * 25 * '"' Figure 3 illustrates a two-roll coating apparatus with additional coating rollers counter-rotating and forming gap-forming transfer rollers.

! : j The basic construction corresponds to Fig. 2, which is why the same construction! the same reference numerals have been used for neos. At least one free space is provided for each of the coating rolls 1 and 2; , ·, With a spray nozzle device 5a or

i «I

5b provided with transfer rolls 16 or 17. Overlapping rolls 1 or 2 t »* i I · and transfer rolls 16 or 17 each form a slot 30 or 31. Transfer rolls 16 and 17 are preferably hal-35 * 1 smaller in size than overlay rolls 1 and 2 which results in a velocity difference between the coating surfaces 1 and 2 and the surfaces 11 and 18 and 12 and 19 of the sheathing rolls 16 and 17 i * respectively. This difference in velocity promotes stretching of the coating film 9 108848 and thus enhances the dosing effect.

Figure 4 illustrates the possibility of pre-dosing the coating paint directly to the coating roll of the two-roll coating apparatus by means of a closed mass rotation. The basic construction of a two-roll casing device corresponds to Figures 1-3, and therefore the same reference numerals have been used for the same elements. The coating pulp is fed directly to the surface 12 of the sheath 12 of the coating roll 2. The pulp feed comprises a pressurized container 10 together with an outlet line 21 extending substantially over the entire machine width. The through-flow cross-section of the outlet conduit 21 must be varied in cross-section, but constant over the entire spreading width.

Applying to the application roller 1 is effected by an open pulp circulation 25 having, for example, a central open container 26 provided with an overflow guard and an outlet element 27 to direct the coating mass to the surface 11 of the coating roller 1. In order to adjust the dosing effect like an effective contraction.

»#> I t» t ·

Fig. 5 illustrates a two-element coating machine, * ♦ 25 '* | *, comprising a compression extension extended with the coating roll 1 | The coating roll 1 is then provided with a free jet nozzle element 5a.

* * f, Il The rotating belt 22 will be coated with a belt adhesive pen:. *; by passing through the filled container, whereby the amount of glue carried by the belt 30 22 is leveled by a trailing blade 24 in the running direction.

1 * i tl.

The structure example depicted in Figure 5 is advantageously available in the two-sided coating of different coating agents, whereas the structures described in the dents 1-4 are best intended for mutual coating with the same coating agent. Here too, a different or only one-sided * i 5 10 108848 coating is conceivable. In the structures illustrated in Figs. 1-4, there is also the possibility of placing both coating elements in the same coating unit.

10 15 20 • · · 25;: · • · · 30.

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Claims (13)

A method for coating a fiber web at least one-sided with a coating material in a two-element coating device having two opposed coating elements (1, 2; 1, 22) forming a gap (3, 23) through which a fiber web (4, 23) is inserted. wherein the coating agent is pre-metered on at least one coating roll (1, 2) and transferred to the slot (3, 23)! 10, characterized in that the pre-dosing is effected by at least one free jet of coating material (13) directed directly onto the surface (11, 12) of the coating roll (1, 2). 2. Förfarande enligt patentkrav 1, kännetecknat av att den »» *; * fria strälen (13) och / eller bestrykningsvinkeln som den bil-: / 'j Dar, kan varier. • '* II' .35 3. anordning för bestrykning av en fiberbana (4) ätminstone) ensidigt med et bestrykningsämne, wagering anordning and finssedell med motinsatt riktning arbetande j 108848 14 bestrykningselement (1, 2; 1, 22), sinsemellan bildar en spalt (3, 23) för genomförande av fiberbanan (4), och i vilken anordning bestrykningsenheten ar försedd med ätminstone et bestryk-5 ningselement (1, 2, 24), kännetecknad av att bestrykningsenheten omfattar en av ät alstrad fri sträle (5a, 5b) som ätminstone indirekt fördose-rar bestrykningsämnet pä bestrykningselementets (11, 12). 10 Method according to claim 1, characterized in that the free jet (13) and / or the coating angle formed by it can be changed. Apparatus for coating the fiber web (4) at least on one side with a coating material provided with two opposed coating elements (1, 2; 1, 24) forming a central web (4, 23) of the fiber web (4). ) through which, and in which device, 25 coating units are provided with at least one coating. ··· element (1, 2, 24), .Y characterized in that ". * coating unit comprises at least one device. To provide a free jet (5a, 5b) which at least indirectly pre-dispenses the coating material onto the outer surface (11, 12) of the coating element. The device according to claim 3, characterized in that: The device (5a, 5b) for immediately generating a free jet is disposed immediately in the coating element. L ": The device according to claim 3, wherein the coating element is a coating roll (1, 2) and wherein 1 The coating unit 108848 further comprises a transfer roll (16, 17) disposed on the coating roll so as to form a compression slot (30, 31), characterized in that the device (5a, 5b) for generating a free jet (13) is disposed on the transfer roll (16, 17). ). 4. Anordning enligt patent krav 3, the tongue pads being attached to a substrate (5a, 5b) and directly directed to the bestrykningselementet. Anordning enligt patent claim 3, wherein the bestrykningselementes (1, 2), and the bestrykningsenesten omfattar dessutom en end the bestrykningsvals (16, 17), att de till-20 sammans bildar et pressnyp (30). , 31), the translucent ad att anordningen (5a, 5b) för alstrande av den fria strälen är «f placerad pä överföringsvalsen (16, 17). t I <*% it> '; 25 6. Anordning enligt face av patentkraven 3-5, kännetecknad av att anordningen (5a, 5b) för alstrande av den fria strälen' (13) bestär av ätminstone ett munstycksaktigt element (en; · . manstycksanordning för den fria strälen). , 30 7, Anordning enligt patentkrav 6, kännetecknad av attitementen för munstycket för den fria strälen kan justeras i förhällande till bestryknings- (1, 2) eller överföringsval- 'j sernas (16, 17), 18, 19). .35 8. Anordning enligt patentkrav 6 eller 7, turnstile av; att munstycksanordningen (5a, 5b) för den fria strälen är arrangererad i förhällande account bestryknings- (1, 2) eller över- 15 108848 föringsvalsernas (16, 17) mantel, att de sinsemellan bildar en i bestrykningsvalsverfings -riktning avsmalnande springs. 9. An anatomy of the face of a patent crease 3-5, a turn-off of an anatomy (5a, 5b) for the purpose of an inertia (19) med en trycksatt behällare (20). Device according to one of Claims 3 to 5, characterized in that the device (5a, 5b) for generating a free jet (13) consists of at least one nozzle-like element (free jet nozzle device). Device according to Claim 6, characterized in that the position of the outlet of the free jet nozzle is adjustable with respect to the surfaces (11, 12, 18, 19) of the cover (1, 2) or transfer rolls (16, 17). Device according to Claim 6 or 7, characterized in that the free jet nozzle device (5a, 5b) is disposed in relation to the surface of the coating (1, 2) or transfer roll (16, 17) so as to form a coating or a gap narrowing in the direction of rotation of the transfer roller. f 9 Device according to one of Claims 3 to 5, characterized in that the device (5a, 5b) for forming a free jet is a closed mass feeder (19) provided with a pressurized container (20). 10. Anordning enligt face av patentkraven 3-9, varnishing tongue av att tvärsnittet i den fria strälens utloppsöppning kan in-ställas variably. Device according to one of Claims 3 to 9, characterized in that the cross sectional area of the free jet outlet is adjustable. Device according to one of Claims 3 to 10, characterized in that, after the device forming the free jet (5a, 5b), smoothing devices (14, 15) are connected. I »108848 s I 13 11. Anordning enligt face av patent kraven 3-10, tongue pads 15 av att man i lupriktningen efter den anordning som frildar den fria strälen (5a, 5b) dessutom har anslutit utjämningsanord-ningar (14, 15). 11 108848 i] 12. Anordning enligt patentkrav 11, a turn-off box av att ut-jämningsanordningen är utformad säsom luftknivar. Device according to Claim 11, characterized in that the leveling devices are made in the form of air brushes. Apparatus for coating at least one side of a fiber web with a coating material provided with two opposed coating elements (1, 2, 22) forming a gap between each other for passing through the fiber web (4), wherein at least one coating unit is provided on the coating unit 10. (1, 2, 22), characterized in that the coating unit is made into an open pulp feeder which at least indirectly spreads the coating material onto the outer surface (11, 12) of the coating element (1, 2) and that the pulp feeder 15 is provided with means for dispensing the application amount. 20 1. Förfarande för bestrykning av fiberbana ätminstone ensi- digt med et bestrykningsämne i en tväelements-bestryknings-anordning som omfattar tvä sinsemellan i motsatt riktning ar- »· betande bestrykningselement (1, 2; 1, 22), viva sinsemellan * t I bildar en spalt (3, 23) genome weaving fiberbanan (4) leds,,, d * 25 colors bestrykningsämnet fördoseras pä ätminstone en bestryk-: ningsvals (1, 2) och överförs i spalten (3, 23) pä fiberbaan , the rotation of the att att fördoseringen sker med ätminstone en fri bestrykningsämnessträle (13), the som circumference of the direct striking be-strykningsvalsens (1, 2). i (.3 ° 13. Anordning för ätminstone ensidig bestrykning av fiberbana j> V med ett bestrykningsämne, I wear anordning j Iti! * 25 bestrykningselement (1, 2; 1, 22), lively sinsemellan image spalt för genomförande av fiberbanan (4), och i vilken anordning bestrykningsenheten är försedd med ätmin · · '. bestrykningselement (1, 2, 22), kännetecknad av att ti, 30 bestrykningsenheten är utförd som en öppen inloppsläda (25) ,,, som ätminstone indirect applicerar bestrykningsämnet to be strykningselementets (1, 2), yta (11, 12), och att inloppslä-dan är försedd med medel för dosering av den play som appli -: '· ceras. 35