FI111230B - Film transfer applicator device and method of the application chamber defining the inlet side member to lubricate - Google Patents

Description

5, 111230

Film transfer applicator device and a method for lubricating the input side of the application chamber defining means of the present invention relates to an applicator device according to the preamble of claim 1 of paper or paperboard coating film transfer coater used, in particular application device for lubricating the pressure chamber 10 of the front wall kaavineli-men.

The invention also relates to a method of coating paper or paperboard which reduces friction between the post-press nip film and the application chamber limiting member. The limiting member may be a blade or a bar. The lubricant cleans the rod or blade of debris and adhesive residues that run into the collection trough at the base of the limiting member.

The invention relates generally to methods and apparatus for dispensing overlay material to a moving base paper or board carton web so that the coating or adhesive is first applied to the surface of an application roll of an adhesive press. The coating applied to the roll surface is transferred further between the applicator roll and the counter roll.

25

Conventional coating devices, such as short-stay application applicators used for paper web coating, include arrangements for applying the coating material under pressure to an applicator chamber 30, which is confined on the one hand to the doctor blade and to the front blade and By supplying the coating material to the coating pool at a sufficiently high flow rate and pressure level, an overflow or countercurrent is formed, i.e. a flow opposite to the direction of travel of the web. Then, in a direction opposite to the movement of the web, the flow between the front wall and the applicator 2 111230 acts by closing the gap so that no air can penetrate the application chamber.

Conventional coating devices of this type are not completely satisfactory. Finnish Patent No. 61534 discloses a coating device in which the coating material is applied to the web to be coated under pressure at a given volume flow rate. When this method has been used for paper coating, it has been difficult to prevent air passing through the gap formed by the front wall 10 to enter the coating chamber. Air penetration into the coating chamber has resulted in an uneven transverse distribution of the coating composition onto the web.

While it is possible to prevent air from penetrating into the applicator chamber by pressing the front wall against the web, as a result, fibers and other contaminants are released from the web to the coating chamber, whereupon they continue to adhere to the doctor blade, causing blades 20 in the coating. With the coating system comprising a lyric press roll or rolls, excess pressure between the front wall of the coating material chamber and the surface of the roll may cause wear damage to the roll surface, as impurities in the paper web tend to remain in front of the front wall due to excessive pressure.

Another known device for coating a moving web is disclosed in U.S. Patent No. 4,250,211. In this device, closing the front wall of the coating unit to prevent air from entering the application chamber 30 is accomplished by considering the moving web by allowing the coating material to flow through the front wall slot in a direction opposite to the moving web, thereby completely filling the slot. Since the gap between the web and the front wall is typically 35 in the range of 3 to 6 mm, the flow of coating material should typically be 20 to 30 times greater than the amount of 3 111230 of coating material remaining on the web if the gap is to be completely closed. As the surface of the roll is coated, the excess flow of coating material will seal the gap. Even if the flow rate is less than that needed to seal the gap with the coating material, it is still large compared to the coating material layer remaining on the surface of the roll. When the gap is large, the pressure of the coating material chamber cannot be easily increased because the flow resistance of the large gap is low. Thus, if the pressure in the application chamber increases, the overflow or counterflow through the slit respectively increases. If the size of the front wall gap is reduced, e.g., 1.5 mm, even small changes in the throat width caused, e.g., by manufacturing defects, will result in transverse defects in the coating layer, i.e., pro-15 sensory defects. On the other hand, if the gap width is reduced, the pressure in the application chamber may become so high with high flow resistance due to altered fractures that problems in closing the edges of the application chamber may occur.

20

In order to avoid the above-mentioned drawbacks, said. arrangements, improvements have been made as disclosed in U.S. Patent No. 4,250,211. In said patent, the coating material is compressed in a limited area or zone ... 25 onto the surface of the web by hydrodynamic forces. Reference is made in this connection to the arrangements described in U.S. Patents 4,250,211 and 4,839,201 and in German Publication No. 3,338,095. It should be noted that in arrangements where the hydrodynamic forces are applied to apply the overlay material, it has still been necessary to use overflow or reverse flow of the overlay material between the front wall of the overlay and the web.

U.S. Patent 4,839,201 describes a device wherein the application chamber is closed by two blades or <4,111,230 alternatively by two rods. The coating is applied by means of the device to the application roll, and therewith to the web to be further coated. There is no actual backflow 5 between the blade or rod and roll of the application chamber, but a uniform layer of water, coating adhesive or other liquid lubricant is applied to the rod or blade, for example through holes in the barrel. A lubricant pool is formed in front of the front stop member to prevent friction between the dry stop member and the applicator roll from damaging the roll or stop member. Although this device does not require the actual return flow from the stop rod or blade, it is necessary to remove the lubricant and any coating or glue that has been removed by the stop member from the roll.

15 The same material used to lubricate the web is most preferably used for lubrication, since in this case any lubricant entering the applicator chamber will not dilute the lubricant. Water may be used in place of the coating composition or adhesive, but may dilute the substance in the applicator chamber or form a layer on the surface of the applicator roll to prevent the coating or adhesive from adhering uniformly to the roll. Thus, water lubrication can cause defects in the coating. The handling of water or other lubricant is difficult due to splashing and because the lubricant must be collected from the lubrication point and returned to either the coating or adhesive circulation or, when using water, to the waste water circulation.

If the lubricant used is adhesive or coating composition used for bonding the surface of paper or cardboard 30, a non-return coating is not possible with the device described above because of the need to provide a return cycle for the applicator front wall blade or rod lubricant. Even if the amount of 1 lubricant could be kept small, the cost of carrying out the return cycle is 35, and the cycle return coating is always of lower quality than the 5111230 fresh coating or adhesive.

It is an object of the present invention to provide a non-return film applicator applicator.

5

The invention is based on the fact that the defining member of the front wall of the applicator chamber is lubricated with steam injected into the nip between the member and the applicator roll.

More specifically, the film transfer coating applicator according to the invention is characterized in what is set forth in the characterizing part of claim 1.

The application method according to the invention, in turn, is characterized by what is set forth in the characterizing part of claim 5.

The application method according to the invention is characterized in what is stated in the characterizing part of claim 8.

The invention provides significant advantages in the coating technique, since lubricating the front wall of the coating device with steam produced by a steam nozzle allows for a smoother end product. Also, the presence of sharp wires in the coated final product is reduced because the condensing vapor cleans the front wall barrier member from possible contaminants such as loose fibers and debris adhering to the roll surface. The most important advantage, however, is that the coating cycle can be made non-returning, i.e. all the coating to be applied to the application chamber is applied to the application roll. In this case, the application device does not require a coating return system and the application chamber always receives fresh coating. The quality of the top coat remains good because it does not mix with air or impurities and the equipment remains cleaner. The coating amounts to be handled are smaller since no additional coating or adhesive is needed in the application step. Surface sizing of paper or cardboard achieves a completely non-return system since surface-5 adhesive is not scraped after application. Of course, in coating, scraping or other smoothing, the excess coating removed from the web must of course be handled appropriately.

The invention will now be explained in more detail with reference to the accompanying drawings.

Figure 1 is a side elevational view of one embodiment of the invention.

15

Figure 2 is a side sectional view of another embodiment of the invention.

The present invention relates to a coating process and apparatus as described in United States Patent 20,4839,201, so that reference is also made to that patent. The device is suitable for applying a surface adhesive or various coating agents by means of an applicator roll, and the substances and mixtures which are generally applied to the web can be referred to as treating agents.

One coating device 10 according to the invention is shown in Figure 1. The device 10 includes an applicator chamber 2, which is limited to area B of the applicator roll 1. 30 Scraper blade 4 and dam blade 3. Scraper blade 4 is a low-angle blade and is loaded with a pressurized hose 5. Normally, the operation of the device can be adjusted to the scraper current by adjusting the position and angle of the frame beam 8 relative to the applicator roller. These adjusters are not described herein.

7, 111230

The application chamber 2 is very small, so the turbulence caused by the surface of the movable roll 1 is minimal. In the solution of the invention, the amount of coating to be applied is kept equal to the amount of coating transferred to the roll (1), since no lubricating by-pass is required. In order to apply the coating layer to the rotating roller 1 and to ensure the uniformity of the coating layer, air must be prevented from entering the application chamber 2. In previous solutions, this has been done by directing part of the coating dosing flow in front of the dam blade 3 against the direction of rotation of the roll 1. The by-pass then acts as a sealing lubrication flow for the dam blade 3. In the solution of the present invention, the applicator chamber 2 is sealed against the roller 1 15 directly against the applicator roller 3 which is pressed against the application roller by a blade holder 18. In this case, the lubricating flow usable-20 intoxicated. The gap between the damper blade 3 and the roller 1 must therefore be lubricated in some other way. In the solution according to the invention, the lubrication is done by spraying steam into the gap between the barrel blade 3 and the appliance roller 1 by means of a steam nozzle 7. Here, the steam nozzle is a tube with a narrow elongated nozzle slot 25 on its side.

• ·

A thin coating or adhesive layer remains on the surface of the applicator roll 1 even after it has passed through the press nip formed by the applicator roll 1 and the counter roll. A large portion of the coating is transferred to the web being processed in the press nip, but a thin film is always left on the web surface. Steam injected into the gap between the applicator roll 1 and the dam blade 3 effectively reduces friction between the bar blade 3 and the film on the roll 1. The reduction in friction is due in part to the softening of 35 films by the action of moisture and heat and partly to condensation of water. Under suitable conditions, the condensable water forms a thin condensate water film under the dam blade 3 which separates the blade 3 from the roll 1. Since the amount of water contained in the steam is small, the amount of condensing water is also very small and does not affect the surface of film, so steam lubrication can eliminate water lubrication problems. Steam condensing water and hot steam clean the dam blade 3 from debris and solidified adhesive or coating. Condensed water and impurities can be collected in a collecting trough located at the base of the dam blade. The condensation of the vapor can be promoted by cooled structures, for example by providing the blade holder with cooling-water circulation.

In the above example, the coating smoothing member is a doctor blade and the front wall is formed by a corresponding member, called a barrier blade in the front wall. Note that depending on the particular application used, the front wall may be oriented in any suitable manner and the blade angle used may vary, for example, from 0 ° to 180 °.

Fig. 2 shows an arrangement where the scraper member is a rotatable rod 12 attached to a rod cradle 11. The rod 12 and the cradle 11 of the rod 25 are supported by a pressurized hose 14 on the coating device body 13 for adjusting the scraping force of the rod 12. As a scraper rod 12, a smooth rod or a grooved rod can be used as required. The front wall of the applicator chamber 2 is also delimited by a barrel 16 fitted to the barrel cavity 16. The bar 15 is supported by a pressurized * hose 17 on the body of the device. than with a grooved scraper-35. The grooved rod also easily releases adhesive or coating through the grooves in front of the rod. The front rod or barrier rod 15 is lubricated from the nozzle 7 with inflatable steam, which at the same time cleans the rod and lubricates the gap between the applicator roll 1 and the dam rod 15. The contact force '5 between the rod 15 and the applicator roll 1 is kept desired by means of a pressurized hose 17. The rod 15 must be pressed against the applicator roll 1 so that no adhesive, coating or other processing agent can pass from the applicator chamber 2 against the direction of rotation of the roll. Since there is no gap-closing by-pass 10 between the dam rod 15 and the roll, it is very important that the rod is tight against the roll 1 to prevent air from entering the application chamber. As the applicator chamber 2 is otherwise closed, material is discharged therefrom only by passing through the scraper rod 12 and no by-pass occurs. The device thus operates 15 without a return cycle. The fall rod 15 may be cooled to promote vapor condensation with lubricating water circulating within the rod cage or by providing a cooling water circulation within the rod or in the rod cradle. 1 2 3 4 5 6 7 8 9 10 11

In each of the above-described embodiments, the vapor 2 may be isolated from the surrounding hall space by suitable means, for example 3, with sufficient enclosure. The need for enclosure depends on the amount of steam 4 used and minor amounts of steam can be let into the room.

6 7 * · '8

In addition to the above, the present invention has other embodiments. The lubricating steam may be supplied to the dam member 9 by a slot-like nozzle as described above, or by separate nozzles attached to the tube 10 having a separate supply of steam 11 ··· or by other suitable means. If desired, a scraper blade and a bar-shaped barrel or barrel and a scraper bar can be combined in the same device. The holders and loading members of the blades and rods can be implemented in many ways.

Claims (10)

10 111230 A film transfer coating applicator (10) for applying a paper or board web treatment agent to a surface of a rotating applicator roll (1), the applicator (10) comprising: - an applicator chamber (2) defined by an area (B) on a rotating applicator roll (1); an applicator (10) comprising a scraping member (4, 12) extending substantially over the surface of the roll (1) along its longitudinal axis and in the direction of rotation of the roll (1) before the scraping member (4, 12), extends substantially over the surface of the roll (1) along its longitudinal axis, and - means (6) for supplying a treatment agent to the applicator chamber (2), 20 - known from means (16, 17; 18) for pressing the barrier means (3, 15). and (7) for supplying steam between the applicator roll (1) and the dam member (3, 15) for the application of steam between the applicator roll (1) and the dam member (3, 15), and , 15) for lubrication. Applicator (10) according to claim 1, characterized in that the barrier means is a smooth rod (15). Application device (10) according to Claim 1, characterized in that the dam element is a dam blade (3). 11 111230 Applicator (10) according to Claim 1, characterized in that a cooling water circulation is provided in the dam member (15) or its holder (16, 11) for condensing the steam. 5 A method for applying a treating agent to a rotating applicator roll (1), further applying it to a paper or board web to be treated, comprising: feeding a treating agent into an applicator chamber (2) delimited by a region (B) on a surface of a rotating applicator roll (1) 10) comprising a scraping member (4, 12) extending substantially over the surface of the roll (1) along its longitudinal axis 15 and in the direction of rotation of the roll (1) in front of the scraping member (4, 12) extending substantially over the roll (1). 1) over the surface along its longitudinal axis, characterized in that: - the dam member (3, 15) is pressed against the surface of the applicator roll (1) such that the treatment medium flows against the rotational direction of the roller (19) and (1) is blocked, and - in the gap between the dam member (3, 15) and the applicator roll (1), steam is supplied to lubricate the dam member (3, 15). Method according to Claim 5, characterized in that the application chamber (2) is supplied with a treatment substance in an amount corresponding to the amount of coating f applied to the surface of the application roll (1). Method according to claim 5 or 6, characterized in that the dam member (15) or its holder is cooled. A method for treating a paper or board web with a treatment agent, comprising: - applying a treatment agent to the film transfer coating applicator roll (1), - leading the web to be treated to a film transfer coating roller nip, 1) an applicator chamber (2) delimited by an area (B) on the surface of a rotating applicator roll (1) and an applicator (10) comprising a scraper member (4, 12) extending substantially over the surface of the roll (1) and (1) in the direction of rotation before the scraper member (4, 12) si-20 divides the dam member (3, 15) extending substantially over the surface of the roller (1) along its longitudinal axis, characterized in that the 25 "dam member (3, 15) against the surface of the applicator roll (1) such that the flow of the treatment agent against the direction of rotation of the roll (19) between the lime (3, 15) and the roll (1), and steam is supplied to the gap between the threshing member (3, 15) and the applicator roll (1) to lubricate the threshing member (3, 15). A method according to claim 8, characterized in that the treatment agent is an adhesive. 111230 13 Method according to claim 8, characterized in that the treatment agent is a coating composition. t I 4 14 111230