NO813401L - COVER IRRIGATION DEVICE - Google Patents

Abstract

The invention relates to a device for one-sided or two-sided coating of a substantially vertically upwardly movable web, in particular a paper web (1). An excess of coating mass (16) is applied to the web (1) and leveled by pulling the web through a coating bundle (4) comprising a flexible coating blade (2) and a retaining member (3). Et '. coating chamber (7), which comprises devices (13) for 1 supply of coating mass (16), are arranged under coating | |. ningsknipet (4). This chamber (7) is open to the path (1) and. has in its bottom portion, at a considerable distance from the coating pinch (4), a narrow slot (5), through which the web (1) moves substantially without touching the edges of the slot. The supply of coating mass (16) to the coating chamber. (7) and the width of the bottom gap (5) are so adapted to the speed of the web (1) and the viscosity of the coating mass (16) that only a very small amount of coating mass flows down through the gap (5) during normal operation of the device. The object of the invention is to provide good coating economy by reducing the amount of recycle coating mass to a minimum.

Description

The invention relates to a device of the type specified in the preamble to patent claim 1.

In coating devices where the web to be coated is pulled upwards through a blade coating clip, in which et|ibe-

•ironing blade evens out the coating compound, coating compound is applied to the path below the coating nip. In a known construction, the application device comprises two rollers, which form a nip, through which the web is drawn. Coating mass is applied to the rollers, which transfer the mass to the track. At high web speeds, difficulties arise due to the web<;>slipping in the application pinch, which means that the transfer|of coating mass to the web becomes uneven. The pressure in the application nip can indeed be increased, so that web slippage does not occur in the nip, but this entails an increased risk of web breakage, among other things, because the massive application rollers, due to j their inertia, do not so easily keep up with changes in web j the speed. Another known coating construction comprises; ter extruders instead of application rollers. extrusion in the application of coating compound usually entails difficulties with regard to the evenness of the application. A common feature of the solutions mentioned is that a j; part of the coating compound in the application phase is not taken up by in the lane. This overflow length must be pumped back to the application unit, which has a negative impact on the efficiency of the coating device. In addition, an additional return system must be provided for the mass scraped off by the coating blade, which makes the device complicated and entails increased manufacturing costs. j

! 1

The purpose of the invention is to provide a track coating device, in which the application of the coating compound can also be carried out at high track speeds in a reliable and economical manner, which gives a homogeneous and even result. A device according to the invention can be produced at a relatively low cost and the amount of coating compound that must be returned by pumping is extremely minimal. This results in a significant benefit in improved coating economy. Also, the coating compound that is scraped from the path of the coating blade is collected for immediate reuse without any pumping system being required for

■ this.

The characteristics of the invention appear from patent claim 1. By carrying out the coating plant in this way, the purpose of the invention is fulfilled. The web is in direct contact with the coating mass in the coating chamber. This contributes to an even and safe application of coating compound over the entire track. The amount of coating compound scraped off by the coating blade will also be directly collected at high track speeds directly in the coating chamber and thus returned to the coating process without pumping. As only very small quantities of coating material pass ■ through the bottom gap of the coating chamber, an accumulation of coating material is formed in the coating chamber and thereby an extensive contact surface is achieved between the coating material and the moving path. When the viscosity of the coating compound and| the track speed is optimally adapted to each other, coming, no one

in part of the coating mass to flow out through the bottom slot of the coating chamber. This achieves the best possible coating economy and no return pumping of coating compound is needed at all. j

The level of the coating compound in the coating chamber can be easily regulated by means of an overflow channel or an over-! flow edge whose position in the vertical direction should preferably be adjustable. The bottom gap of the coating chamber should suitably have a width that does not exceed 5 cm, preferably not exceeding 1 cm. In the latter case, outflow of coating material through the bottom gap can be completely eliminated even at low web speeds. . The coating can conveniently be carried out with a coating compound whose dynamic viscosity is higher than 1 mPas. As a result, the use of, for example, water-soluble adhesive components will require relatively small amounts of water, which reduces the need ; for lane drying and thereby improves the overall economy of the coating process.

I I

Such coating mass which has possibly flowed down through the bottom slot of the coating chamber is collected in a container or a trough below the slot. The coating mass that flows out via the coating chamber's level control devices can also be collected in the same containers.

In a preferred embodiment of the invention, wine is kept. wedge between the web and the coating blade less than 40°. This makes it easier to mount the blade and reduces the risk of damage on the pitch. According to the invention, a movable roller can be used as a counter-hold in the coating pinch. The roller rotates in the same direction as the web and its peripheral speed is at least substantially equal to the web speed. This embodiment is particularly suitable, for example, when the web simultaneously undergoes adhesive press coating and pigment coating adhesives are applied. The same device can also be used for normal single-sided coating. It can be used just as well at low as at high track speeds.

The coating clamp's counter-hold can also be designed as a plate or disc which in vertical direction extends approximately from the bottom part of the bottom trough to a point slightly above the coating clamp. The width of this plate or disk should be equal to the width of the track or greater. In this way, a simple and reliable support for the track is achieved and, at the same time, only one element is needed to form the coating clamp's resistance and ! one edge of the coating chamber's bottom gap.. j

In a device according to the invention, the construction! , elements located on opposite sides of the path be]i 1 .i j completely or partially identical. In double-sided coating, a coating chamber can be arranged on each side of the web, preferably at the same height. These chambers can be fed with the same or different types of coating compound. In the latter case;

the width of the coating chamber's bottom gap and the level of the coating compound in the coating chamber can be significantly different on the two sides of the web.<j>j To provide an even coating result, ber

', the ironing board is suitably equipped with a device<il>.' which gives the opportunity to regulate the clamping pressure. Such devices are known per se.

The invention shall be described in more detail below with reference to the attached drawing.

Fig. 1 is a schematic perspective drawing of a device according to the invention.

[Fig. 2 shows a section of a first embodiment of oppy

f; the entry. ii

Fig. 3 shows a section of a second embodiment of the invention. Fig. 4 shows a section of a third embodiment of the invention. Fig. 5 shows a section of a fourth embodiment of the invention. In the drawing, 1 denotes a moving path, which is drawn through a coating clip 4 formed by a flexible coating. blade 2 and a counter-holding element 3. The path's direction of movement is indicated by an arrow. A narrow gap 5 is present below the coating pinch 4. This gap is formed between a gap-limiting element 6 and the edge 11 of a gap width regulator 10. The gap width can be continuously regulated up to a maximum of preferably 5 cm. The resistance element 3 and the gap limiting element 6 can be made up of separate elements

or be combined into a common unit, which can be constituted

i of a roller, a flexible or fixed plate or a stationary web control unit. Above the gap 5 there is a substantially closed coating chamber 7. This chamber is limited by the web 1, by the coating blade 2, by a rear wall 8 and by side walls 8a. A support plate 9 is connected to the gap width regulator 10, which is movably suspended, so that it can affect the width of the gap 5. The gap width regulator 10 can

, for example, be provided with threaded elements, the rotation of which affects the width of the gap 5.

Coating compound 16 is supplied to the chamber 7 through a supply channel 13. Below the slot 5 there is a collection tank

12, which is open to the path 1. The small amounts of coating compound that run down through the slit-5 are collected in the tank

■12 and is returned to the chamber 7 through a channel 14, which is connected via a pump (not shown) to the supply channel 13. The chamber 7 is provided with devices to regulate the level of the coating compound. Coating compound can, for example

flow over the side wall nés 8a upper edge 8c of the tank 12. i The overflow hinge edge 8c is suitably vertically adjust- ! bar.

The embodiment according to fig. 3 comprises a roller 15, which also forms a counter-hold for the coating blade 2 and at the same time

delimits the coating chamber's bottom gap 5. The roller 15j ! rotates in the path's 1 direction of movement.

The embodiment according to fig. 4, which is mainly symmetrical in relation to path 1, is used for two-sided coating. i It is not necessary to make the device symmetrical. If J

different types of coating compound with different viscosities are supplied, the coating chambers 7 on opposite sides of the track>. the width i of the bottom gap 5 must be regulated differently in relation to the level in the coating chamber.

j The collection tank 12 is supported by the wall of the coating chamber. 8. The tank 12 can also be formed in one piece with the wall 8 by equipping the latter with a long downward part, which at the bottom is bent upwards towards the path 1, so that a collection trough is formed. The trough or tank 12 can extend beyond the side edges of the track 1.

i The counterhold of the coating clamp and the limiting element of the bottom gap 5 can be formed by a single, mainly rigid, web: guiding plate 17> as shown in fig. 5. !

'.. ■ ' ■ ' J

•■ ■ ! IN

The invention is not limited to the embodiments shown, as a majority of modifications and variants are conceivable: within the scope of the patent claims below. For example, can . the gap width regulator 10 is made up of a rotatable element, which is connected to the inside of the side wall of the coating chamber. In this case, the axis of rotation of the gap width regulator is arranged so that it is parallel to the gap 5 and eccentric.

in relation to the gap width regulator 10.

Claims (8)

1. Device for one-sided or two-sided coating of a !mainly vertically upwards moving web, preferably 1 a paper web (1), by applying an excess of coating-! mass (16) on the web (1) and level it on the web remaining' in mass by pulling the web through a coating clip (4) comprising, a flexible coating blade (2) and a counter-holder element (3), characterized in that a coating chamber (7) 7 comprising devices (13) for supplying coating compound (16) is arranged under the coating nip (4), which chamber (7) is open to the web (1) ) ; and in its bottom part, at a considerable distance from the coating pinch (4), has a narrow gap (5), through which the web (1) moves mainly without touching the edge of the gap, ; .and that the supply of coating compound ■ (• 16) for coating • in the !chamber. (7) and the width of the aforementioned slot (5) are thus adapted to the speed of the web (1) and to the viscosity of the coating mass (16), so that only a small amount of coating mass flows down through the slot (5) during normal operation of the device. ' 2. Device as set forth in claim 1, characterized in that the level of the coating mass (16) above the above-mentioned j 'gap (5) is regulated by means of a preferably vertical adjustable overflow channel or overflow edge (8 c). j 3. Device as stated in claim 1 or 2, k a r a k in that the width of said column (5) . t is at most 5 cm, preferably at most 1 cm. 4. Device as stated in one of the preceding claims, ! : characterized in that the coating compound (16) has a dynamic viscosity that is higher than 1 mPas. 5. Device as stated in one of the preceding claims, characterized in that in the below-mentioned t i slot (15) there is a collection tank (12) or a collection tank (12) .in collection trough for collecting such coating mass, so1m . flows down through the slot (5). 6. Device as specified in one of the preceding claims, . characterized in that the angle between the web (1) and the coating blade (2) is less than 40°. 7. Device as stated in one of the preceding claims, characterized in that the counter-holding element (3) in the coating nip consists of a roller (15), which follows the movement of the web (1). 8. Device as set forth in one of claims 1 to 6, characterized in that the coating pinch (4)'s counter element consists of a plate (17), which extends from a level below the coating chamber's bottom slot (5) to a level above the coating pinch (4) .