Liquid coating die

A coating die that includes a removable manifold section with each side of the manifold section defining a manifold, a land, and an outlet or lip. The two manifolds, lands and outlets may be the same or different, respectively. The manifold section is removably connected to at least one die body and can be removed from the die body to switch between the two sides of the manifold section. The coating die is designed and configured for web or substrate coating, either on-roll (supported web) coating or off-roll (tension web) coating.

FIELD

The present invention relates to coating dies or applicator dies for applying a liquid coating material to a moving sheet or web. In particular, the present invention relates to a coating die having a removable and replaceable portion that defines two manifolds, two lands and two outlets.

BACKGROUND

A coating die is used to apply a thin layer of liquid material (e.g., thermoplastic or solvent based) to a support substrate such as a sheet or film. The most common coating process is to provide a continuous layer of coated material on the substrate by having a continuous stream of material applied to the moving substrate.

A coating die includes at least an inlet for receiving the material to be coated, a manifold to distribute the material across the width of the coating die, and an outlet through which the material exits the die. The exact configuration of the die will vary depending on the material being coated, the desired coating properties (i.e., allowable pressure drop, flow rate, etc.), the desired coating width, etc. If a coating line or facility interchangeably runs numerous types of coatings, then the facility needs to have an inventory of different dies. Because a coating die is a very expensive piece of capital equipment, large amounts of money are tied up in the various dies.

Many facilities have at least one back-up coating die for occasions when the die being used gets damaged. Again however, the facility needs to have an inventory of back-up dies.

BRIEF SUMMARY

The present disclosure relates to a coating die that can decrease the inventory of coating dies needed by a facility. In most instances, the coating die of this invention reduces the number of inventory dies by half.

The coating die of this invention includes a removable and replaceable manifold section that includes two coating material paths; that is, the manifold section includes or at least partially defines two manifolds, two lands, and two outlets. While the first coating path is being used for applying a material, the second coating path may be idle; for embodiments where the second coating path is the same as the first coating path, the second coating path is a back-up; for embodiments where the second coating path is different than the first coating path, the second coating path is a second die suitable for use in a different coating application. In some process embodiments, the two coating material paths may be used simultaneously to provide a multiple layer coating. In other process embodiments, while the first coating path is being used for applying a material, the second coating path may be used to affect the first coating, either prior to or after being applied. For example, the second coating path may be used to pull a vacuum to reduce the amount of air bubbles entrained in the material being coated. As another example, the second coating path may be used to impinge air (e.g., as an air knife) into the coating. The two coating paths may be used for additional processes.

In one particular embodiment, this invention is directed to a coating die having a first die body, a second die body, and a manifold section. The manifold section has a first side and an opposite second side, and is removably connected to the first die body and to the second die body. Together, the first die body and the first side of the manifold section define a first manifold configuration and together, the second die body and the second side of the manifold section define a second manifold configuration. Either or both of the manifold configurations may include a manifold, a land, and an outlet. The first manifold configuration may be the same as or different than the second manifold configuration.

In another particular embodiment, this invention is directed to a coating die having a first die body and a manifold section removably connected to the first die body. The manifold section has a first side and an opposite second side, the first side defining a first inlet, a first manifold and a first land and the opposite second side defining a second inlet, a second manifold and a second land. In some embodiments, a second die body may be removably connected to the second side of the manifold section. The first inlet, the first manifold and the first land may be the same as or different than the respective second inlet, second manifold and second land.

In yet another particular embodiment, this invention is directed to a method of coating using a die having a manifold section that is removable and replaceable from between a first die body and a second die body. The first die body and a first side of the manifold section define a first manifold and a first land, and the second die body and a second side of the manifold section define a second manifold and a second land. The manifold section and appropriate die bodies may also define an outlet.

In still another embodiment, this invention is directed to a method of applying a first coating and a second coating. The method includes applying a first coatable material to a substrate via a first fluid channel defined by a first side of a manifold section and a die body, the first side of the manifold section comprising a first inlet, a first manifold and a first land. The method also includes applying a second coatable material to a substrate via a second fluid channel defined by a second side of the manifold section and a second die body, the second side opposite the first side of the manifold section, the second side of the manifold section comprising a second inlet, a second manifold and a second land. The first manifold and the first land may be the same as or different than the second manifold and the second land, respectively. The first coatable material may be the same or different than the second coatable material. For most embodiments wherein the first manifold and first land are the same as the second manifold and the second land, the coatable materials are the same. When different coatable materials are used, the first coatable material may be applied simultaneously as the second coatable material.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanying set of drawings that form a part hereof and in which are shown by way of illustration at least one specific embodiment. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense. The definitions provided herein are to facilitate understanding of certain terms used frequently herein and are not meant to limit the scope of the present disclosure.

The present disclosure relates to coating dies that include a removable manifold section with each side of the manifold section defining a manifold and an outlet or lip; that is, the manifold section includes at least two manifolds, two lands, and two outlets or lips. The manifold section can be removed from the coating die to switch between the two coating paths. The coating die is designed and configured for web or substrate coating, either on-roll (supported web) coating or off-roll (tension web) coating.

There are various features and benefits to the coating dies of the present invention. As indicated above, each side of the removable manifold section defines an independent fluid channel, which can include a manifold, outlet (die lip), inlet, land, pre-land, and any other die features. Each side of the manifold section operates independent of the other, in that they share no common features; that is, the resulting coating die has two inlets, two manifolds, two outlets, etc.

The two fluid channels may be the same or may be different. If the same, the removable manifold section provides a ‘built-in’ back-up manifold. If the fluid channels are the different, the removable manifold section eliminates the need to have two different dies for two different coating processes; by using the removable manifold section, the manifold section can easily be rotated when switching from one coating process to the other.

In use, one side of the manifold section may be used for coating while the other side is idle. In some embodiments, rather than being idle, the other side may be used to affect the coating. For example, the second side can be used to pull a vacuum on the web/coating solution, e.g., to remove air bubbles from the coating. As another example, the second side can be used as an air knife, e.g., to impinge the coated material into the substrate. As yet another example, the second side can be used as a coolant or water supply, e.g., to quench the coating. And as yet another example, the second side can be used to supply a reactive material (e.g., cross-linker) to the coating. Alternately, both sides of the manifold section may be used for simultaneously applying two coatings to result in a multi-layer coating on the substrate.

As described above, the coating die having the removable manifold section has two fluid channels, comprising two inlets, two manifolds, and two outlets (die lips), the two fluid channels being independent from one another. While the present disclosure is not so limited, an appreciation of various aspects of the disclosure will be gained through a discussion of the examples provided below.

Turning now to the figures,FIG. 1generically illustrates a coating die of this invention, which includes a removable manifold section. The coating dies in accordance with the present disclosure are used to apply a coatable material (for example, a thermoplastic material, solvent based, or a high-solids liquid material) to a moving substrate or web.

Coating die10of the invention includes a first die body12and a second die body14and a removable manifold section15therebetween. In this embodiment, first die body12is an upper die body, as it is positioned above manifold section15and is configured for use with manifold section15to form a coating path and coat material. Further in this embodiment, second die body14is a cover attached to manifold section15opposite first die body12; cover14is not configured for coating use, although in some embodiments it may be used for coating use. Additional discussion regarding a die body being a cover or not is below.

Present between first die body12and second die body14is manifold section15. InFIGS. 3 and 4, the first die body12, manifold section15, and second die body14are each flat plates. Manifold section15is removable from between body12and body14and is flippable in orientation or is replaceable with another (e.g., different) manifold section.

Together, first die body12and manifold section15define a material path extending from an inlet22, through fluid channel24and out from die10via outlet or lip25. Fluid channel24includes a manifold downstream of inlet22, the manifold for distributing the coatable material across the width of the die. The manifold may be any suitable type, such as a horseshoe or Winter manifold, a coat hanger manifold, a fishtail manifold, a t-manifold, etc., and does not affect the inventive features of die10or of manifold section15. Downstream of the manifold may be a preland region prior to a land region that leads to outlet25. Fluid channel24may include other features, such as transition areas or run-out areas. The manifold, preland and land are arranged substantially parallel to and substantially as wide as the corresponding outlet25to provide a uniform delivery of liquid coating material widthwise across the web or substrate being coated. The various features of inlet22, fluid channel24and outlet25are defined by manifold section15. That is, the manifold, preland, land, etc. are present in and at least partially defined by manifold section15. In some embodiments, although not preferred, die body12may define some features of fluid channel24, but usually die body12provides a flat surface against which fluid channel24is formed. Lands and/or outlet25may be adjustable in height so that the thickness of the coating applied can be adjusted as desired. The width of outlet25may be fixed or may be adjustable, for example, by deckling or a deckling system.

Similarly, second die body14and manifold section15define a possible material path extending from an inlet42, through fluid channel44and out from die10via outlet or lip45. As shown inFIGS. 1,5and6, outlet45is spaced apart from outlet25. As with fluid channel24, fluid channel44includes a manifold downstream of inlet42, and an optional preland region prior to a land region that leads to outlet45. Fluid channel44may include other features, such as transition areas or run-out areas. Again, the various features of inlet42and fluid channel44are defined by manifold section15. That is, the manifold, preland, land, etc. are present in and at least partially defined by manifold section15.

Turning toFIGS. 2A-2C, a specific embodiment of a manifold section50according to the invention is illustrated. Manifold section50has a first manifold configuration51present on a first side50A and a second manifold configuration52present on a second side50B. As illustrated, second side50B is parallel to first side50A. Manifold section50is similar to manifold section15ofFIG. 1in that it is attachable to and removable from engagement between a first and second die body (e.g., die bodies12,14).

In this embodiment, first manifold configuration51is different than second manifold configuration52. First manifold configuration51has a fluid channel having an inlet53, a preland55, a manifold57and a land59. First manifold configuration51, specifically inlet53, preland55, manifold57and land59, are present in and at least partially defined by manifold section50; preland55, manifold57and land59are at least partially defined by the surface of first side50A. Second manifold configuration52on the other side of manifold section50has a fluid channel having an inlet54, a manifold56and a land58. Second manifold configuration52, specifically inlet54, manifold56and land58, are also present in and at least partially defined by manifold section50, but manifold56and land58are at least partially defined by the surface of second side50B. First and second manifold configurations51,52are used for different coating processes, optionally with different coating materials.

As an example, manifold section50is attached to a first die body (e.g., die body12) and a second die body (e.g., die body14) in the orientation ofFIG. 3, so that first manifold configuration51is adjacent first die body12, and together first manifold configuration51and first die body12form a fluid channel for receiving coatable material therethrough. Second manifold configuration52, in the illustrated configuration ofFIG. 3, is adjacent second die body14, which is a cover, and is idle.

At a desired time, first die body12and second die body14are removed from manifold section50and manifold section50is flipped, so that manifold section50is in the orientation ofFIG. 4. First die body12and second die body14are then attached to manifold section50to form a second, different fluid channel for receiving coatable material therethrough. Having manifold section50with two different manifold configurations allows a coating facility to store half as many dies as compared to conventional dies, which only have one manifold configuration.

As another example, a manifold section may have two manifold configurations that are the same; that is, the same manifold configuration is present on each side of the manifold section. Having a manifold section with the same manifold configuration on each side allows a coating facility to have a back-up die on hand, in case the first one is damaged and is no longer suitable for use (e.g., outlet lip is chipped, distorted due to heat or pressure, blockage within the fluid channel, etc.).

For the previous discussion, second die body14has been an idle cover, rather than an active die body. A cover is used for embodiments when the manifold configuration on that side of the manifold section is idle and not used for coating. Idle covers do not need to be able to withstand the pressures and temperatures associated with coating, and thus a cover is typically less expensive, occupies less space, and is generally easier to replace if lost or damaged (e.g., dropped) as compared to a die body (e.g., die body12) used for coating. In some embodiments, it may however be feasible to use a cover to define the fluid channel for a manifold configuration used for applying a coating.

The previous discussion has provided examples with the manifold section having two manifold configurations (either two different or two of the same configurations) where only one manifold configuration is used at a time, that is, the other one of the manifold configurations is idle. In other embodiments, both manifold configurations, i.e., both sides of the manifold section, may be used simultaneously. The second side may be used to affect the coatable material or coating being applied by the first side, or the second side may be used to also apply a coating.

A manifold configuration not used for applying a coating may be used to affect the coating that is being applied by the other side. For example, the configuration on the second side can be used to pull a vacuum on the web and/or coating solution (e.g., to remove air bubbles from the coating), as an air knife (e.g., to impinge the coated material into the substrate), as a coolant or water supply (e.g., to quench the coating), or used to supply a reactive material (e.g., cross-linker) to the coating. The ‘affecting’ side may be upstream or downstream from the coating side.

FIG. 5illustrates a process100utilizing a coating die110having a first die body112, a second die body114and a removable manifold section115therebetween. Coatable material to be coated passes through the flow channel between first die body112and manifold section115from a coatable material source (not illustrated), such as an extruder, to outlet125where the coatable material is applied to substrate5as a coating. Second die body114and manifold section115together form an outlet145which is used to affect the coating from outlet125. In this process100, both sides of manifold section115are active and both die bodies112,114are active die bodies.

In process100, the fluid channel between die body114and manifold section115, which terminates at outlet145, is used to pull a vacuum to reduce the occurrence of any air bubbles in the coating material. Depending on the amount of vacuum and its placement, the vacuum can remove a barrier of air from substrate5immediately prior to application of the coating material by outlet125, or the vacuum can extract entrapped air bubbles from the coating material.

In another embodiment, a vacuum may be pulled through side aperture155that is in fluid communication with and leads to port156in the face of manifold section115.FIGS. 3 and 4illustrate manifold section50with a similar side aperture65in fluid communication with ports66. Utilizing ports66/156to pull a vacuum provides a larger vacuum chamber than obtained if using the fluid channel between die body114and manifold section115, which terminates at outlet145.

In this configuration forFIG. 5, coating die110deposits coated material on substrate5opposite a backup roll2. An apparatus such as that ofFIG. 5, which utilizes backup roll2opposite coating die110, is often referred to as “supported web” or “on-roll” coating.

Alternately, both manifold configurations may be used for coating.FIG. 6illustrates a process101utilizing coating die110having first die body112, second die body114and removable manifold section115therebetween. A first coatable material to be coated passes through the flow channel between first die body112and manifold section115from a coatable material source (not illustrated) to outlet125where the coatable material is applied to substrate5, and a second coatable material to be coated passes through the flow channel between second die body114and manifold section115from a coatable material source (not illustrated) to outlet145where the coatable material is applied to substrate5in the form of a coating. Again in this process101, both sides of manifold section115are active and both die bodies112,114are active die bodies.

In process101, a first coating is applied via outlet125to substrate5, over which is applied a second coating via outlet145. The two coatings may be the same or different, in thickness, materials, solids, etc.

In this configuration forFIG. 6, coating die110deposits coated material on substrate5between rollers3and4. An apparatus such as that ofFIG. 6is often referred to as “tension web” or “off-roll” coating.

Coating processes such as illustrated inFIGS. 5 and 6can operate at a wide range of production speeds. For example, it is not uncommon for commercial embodiments of the above arrangements to operate at rates from a few feet per minute to 2000 feet per minute to 4000 feet per minute using webs having widths of less than one foot, one meter, or more. It is understood that substrates of almost any length and/or width can be used with these coating processes. Although in most embodiments the substrate being coated is a flexible substrate such as a polymeric film, rigid substrates may also be coated with the dies and processes described herein.

The physical size of the removable manifold section is generally unlimited. The distance between the sides (e.g., side50A and50B ofFIG. 2A) at the edge that forms the outlet or lips, and thus the distance between the two outlets, can be any desired distance, such as 1 inches, 2 inches, 3 inches, etc., and could be as little as about ½ inch. In some embodiments, a distance of as little as ¼ inch may be feasible. The width of the removable manifold is typically the same as the die bodies to which it attaches; common widths are 6 inches to 3 feet wide, although smaller and larger width dies can also be made.

Thus, various embodiments and features of the LIQUID COATING DIE are disclosed. The implementations described above and other implementations are within the scope of the following claims. One skilled in the art will appreciate that the various features described may be used in conjunction with any of the other features described herein above or other features other than those disclosed. For example, in some processes it may be desired to utilize more than one removable manifold section. Utilizing two manifold sections between two outer die bodies will provide three separate and individual fluid channels with three outlets that can be used in any arrangement to produce coating(s) or affect the coating. As another example, the previous discussion has always described two die bodies, one on each side of the removable manifold section. In some embodiments, however, an idle side of the manifold section may not require the presence of a die body.

The disclosed embodiments are presented for purposes of illustration and not limitation, and the present invention is limited only by the claims that follow.