CONTROLLED PRINTING SURFACE AND METHOD FOR FORMING TOPographical features on a CONTROLLED PRINTING SURFACE - Patent application

Abstract

Provided herein are methods for forming and optimizing hardened features on a surface, the methods including controlling the surface onto which the hardened features are imparted. Also described are systems for forming and processing topographical features on a film, along with mechanical features of specific system stations. More specifically, provided herein are methods for forming and optimizing topographical features imparted to a film surface by controlling the film surface, controlling the direction and magnitude of pressure applied to the film (substrate), and first partially curing the topographical features, followed by fully curing the topographical features to form a film having topographical spacing features formed thereon.

Description

[Technical field]

[0001] The present invention relates to methods of forming and optimizing hardened features on a surface, including controlling the surface onto which the hardened features are applied, and more specifically, the present invention relates to methods of forming and optimizing topographical features applied to a film surface by controlling the film surface by controlling the direction and magnitude of pressure applied to the film. [Background technology]

[0002] The formation of spacer features on filtration devices and reverse osmosis membranes used in such devices is known. The use of a pattern of a curable composition printed on the membrane surface serves as an alternative to a more conventional mesh layer that allows liquids such as water to flow and can keep filtration membranes apart by providing a spacing function. The formation of such a pattern on the membrane appears to have advantages over mesh layers, especially since the pattern is less likely to block flow and accumulate filter debris (commonly referred to as fouling). Furthermore, the spacers placed directly on the surface of the membrane can have a height that is 50% lower compared to conventional mesh spacers. Making the spacer height lower in previous meshes was thought to be impossible because it would dramatically increase the supply pressure and the pressure drop across the element. The lower height of the printed spacer does not appear to significantly reduce the supply pressure. The open design of the printed spacer feature produces a similar pressure drop at a lower height than mesh spacers with closed or fenestrated designs. The benefit of the lower height of the printed spacer is that more film can be wrapped to form the element resulting in the same specific diameter as the previous mesh at the higher spacer height. For example, in some cases, the printed spacer can utilize seven more leaves (i.e., sheets of film) in the same 8" diameter element for a total of 35 leaves instead of the previous 28 leaves (i.e., 25% more). In other cases, three more leaves can be added in a 4" diameter element for a total of 10 leaves instead of the usual seven leaves (i.e., 40% more).

[0003] There are many challenges in commercially producing films having printed curable composition patterns, referred to herein as topographical features: The topographical features must have a size and shape that provides sufficient spacing from adjacent layers, balanced with minimal film surface coverage to allow maximum fluid flow.

[0004] In printing on a film surface, direct contact between the stencil and the film surface is problematic. Such films are delicate and easily damaged during physical contact with the stencil and other parts of the printing device. Flat, uniform and sufficient contact between the stencil and the film surface is necessary to contain the curable composition within the stencil openings and optimize bleeding of the curable composition between the stencil and the film surface. However, too strong or uneven contact between the stencil and the film surface often damages the film.

[0005] Additionally, the membrane can be damaged during numerous steps of the printing process that require handling or movement of the membrane. For example, the membrane must be moved onto and off the printing surface, and may tear as it is dragged across the printing surface. To allow accurate printing, the membrane must be flat on the printing surface. Ensuring that the membrane is substantially flat requires further manipulation of the membrane, again potentially resulting in damage. Additionally, the act of contacting and removing the stencil from the membrane surface also provides an opportunity to damage the membrane.

[0006] Furthermore, many curable compositions are unable to meet the chemical and temperature resistance requirements to withstand the aggressive environments introduced by the cleaning cycles used in these applications. Additionally, the curable composition must have high bond strength to the membrane, while not being too brittle so as to damage the membrane during winding operations, or too soft and flexible so as to compress under pressure in use and lose the specific spacing required. Summary of the Invention [Problem to be solved by the invention]

[0007] A printing method is needed for the curable composition that allows for printing of topographical features on a surface, e.g., a film, that optimizes the topographical features while at the same time minimizing damage to the surface (e.g., film) caused by contact with the stencil and other printing equipment parts. [Means for solving the problem]

[0008] The present invention provides a means to meet the aforementioned needs. The present invention provides a method for forming and optimizing hardened features on a surface, including controlling the surface onto which the hardened features are applied. More specifically, the present invention relates to a method for forming and optimizing topographical features (geometric shapes) applied to a film surface by controlling the film surface by controlling the direction and magnitude of pressure applied to the film.

[0009] In one aspect of the invention, a method is provided for forming topographical features on a film surface, the method comprising: providing a stencil over a first surface of the film, the stencil having openings exposing the first surface for receiving a hardenable composition; applying positive pressure to a second, opposing surface of the film to bring the first surface into contact with the stencil; depositing one or more layers of the hardenable composition in the stencil openings and on the first surface to form the topographical features, the openings defining the approximate shape and size of the topographical features; exposing the hardenable composition to conditions to partially cure the hardenable composition sufficient to retain the topographical features but insufficient to cause adhesion with the stencil; and applying negative pressure to the second surface to separate the film and stencil without disturbing the partially cured topographical features, the positive pressure being sufficient to reduce a halo area around the topographical features by at least 10%.

[0010] In one aspect of the invention, a method of forming topographical features on a film surface includes the steps of providing an apparatus comprising a support for supporting a film having a first surface and a second opposing surface and capable of creating positive and negative pressure on a contacting surface of the film, contacting the second surface of the film with the support, providing a stencil on the first surface of the film, the stencil having an opening exposing the first surface for receiving a hardenable composition, applying positive pressure to the second surface to contact the first surface with the stencil, and depositing one or more layers of the hardenable composition within the stencil opening and through the second surface. A method is provided that includes depositing on a first surface to form a topographical feature, where the openings define the approximate shape and size of the topographical feature; exposing the hardenable composition to conditions to partially cure the film to a state sufficient to retain the topographical feature but insufficient to cause adhesion with the stencil; and applying negative pressure to the second surface to separate the film and the stencil without disturbing the partially cured topographical feature, where the positive pressure is sufficient to reduce a halo area around the topographical feature by at least 10%.

[0011] In another aspect of the invention, there is provided a system for forming a pattern of features on a surface of a substrate, comprising: A. i. a first support for supporting a substrate having two opposing surfaces; ii. a deposition device for depositing a pattern of a curable composition onto at least one surface of a substrate; and iii. A partial curing device for partially curing the pattern of the curable composition to form a partially cured pattern of the curable composition on at least one surface of the substrate. a pre-cure station including: B. a first transport device for transporting the substrate from the pre-cure station to the full cure station; C. i. a second support for supporting a substrate having a partially cured pattern of a curable composition on at least one surface of the substrate; ii. A full curing device that fully cures the partially cured pattern of the curable composition to form a pattern of features on at least one surface of the substrate. Complete curing station including A system is provided that includes:

[0012] In addition, the system D. A second transport device that transports the substrate (film) from the full curing station to a substrate sizing station; E. a third transport device for transporting the substrate (film) sheet to a substrate receiving station, which receives and stores the substrate sheet; It may further include:

[0013] Additionally, the system may include a film dispensing device that dispenses a substrate (film) of a predetermined size, and may further include a cutting device (not shown) that cuts the substrate to size to form substrate sheets. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 shows a typical pattern of topographical features (5) on a membrane (1) for water desalination or brackish water filtration. [Diagram 2] 2A and 2B are diagrams showing the arrangement of a stencil and a membrane showing openings for depositing a curable composition onto a membrane surface in the form of a topographical feature (shown in 3-D) having a desired size and shape sufficient to perform a spacing function when layered with another membrane surface. The aspect ratio of the feature (which provides the desired spacing ability) is shown. FIG. 2a shows the stencil overlaid on the membrane surface, and FIG. 2b shows the stencil and the membrane after the stencil has been removed leaving the topographical feature. [Diagram 3] 3A and 3B are photographs of a topographical feature printed on a membrane and a halo surrounding the topographical feature. The topographical feature in Fig. 3a was printed without the use of positive pressure during application of the curable composition. The topographical feature in Fig. 3b was printed with positive pressure during application of the curable composition. [Figure 4] FIG. 1 is a schematic diagram illustrating various workstations for creating a film having a pattern of topographical features, including deposition, partial curing and full curing stations, as well as a storage or cutting station (not shown). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present invention is directed to methods of forming and optimizing hardened features on a surface by controlling the surface onto which the hardened features are imparted. More specifically, the present invention relates to methods of forming and optimizing topographical features imparted to a film surface by controlling the film surface by controlling the direction and magnitude of pressure applied to the film.

[0016] A method of forming topographical features on a film surface in accordance with the present invention includes providing a stencil over a first surface of the film, the stencil having openings exposing the first surface for receiving a hardenable composition; applying positive pressure to a second, opposing surface of the film to bring the first surface into contact with the stencil; depositing one or more layers of hardenable composition in the stencil openings and on the first surface to form the topographical features, the openings defining the approximate shape and size of the topographical features; exposing the hardenable composition to conditions to partially cure the hardenable composition sufficient to retain the topographical features but insufficient to cause adhesion with the stencil; and applying negative pressure to the second surface to separate the film and stencil without disturbing the partially cured topographical features, the positive pressure being sufficient to reduce a halo area around the topographical features by at least 10%.

[0017] As used herein, the term "halo" refers to the portion of the curable composition on the film surface that extends beyond the area of ​​the base of the topographical feature defined by the stencil opening. As used herein, the term "halo area" refers to the relative area of ​​the halo compared to the area of ​​the topographical feature on the film surface defined by the stencil opening (i.e., the footprint of the topographical feature). The halo area (A h ) is expressed by the following formula: A h =(A c -A tf ) / A tf [In the formula, A tf is the area of ​​the membrane surface covered by the topographical features defined by the stencil openings, and A c is the combined area of ​​the membrane surface covered by the topographical features (defined by the stencil openings) and the membrane surface covered by the halo] It is calculated using A c A tf If equal to , then no halo exists.

[0018] Thus, the percent reduction in halo area produced by the process of the present invention is: A h Reduction% = ((A h(ni) -A h(i) ) / A h(ni) )×100% [In the formula, A h(ni) is the halo area resulting from a normal process, not the present invention, and A h(i) are the halo areas resulting from the process of the present invention, each using the same size and shape topographical features. It can be expressed as:

[0019] In one aspect of the invention, the pattern of topographical features can have a size and shape sufficient to expose enough membrane surface to maintain proper membrane spacing and ensure efficient operation of the membrane. In particular, the total surface area of ​​the membrane covered by the topographical features (i.e., A, defined as the combined area of ​​the membrane surface covered by the topographical features (defined by the stencil openings) and the membrane surface covered by the halo) can be determined by the size and shape of the topographical features. c ) multiplied by the number of topographical features per unit area of ​​the film surface is about 20% or less of the film surface (i.e., at least about 80% of the film surface remains exposed). In one embodiment of the invention, the total surface area of ​​the film covered by topographical features is about 15% or less, or about 10% or less, or about 6% or less, or about 5% or less, or about 3% or less, or about 2% or less, or about 1% or less.

[0020] In an embodiment of the invention, the size of the halo area can be optimized to allow a suitable curable composition to contact the surface and maintain adhesion throughout manufacture and use while leaving sufficient surface area uncovered to allow proper membrane function. In another embodiment of the invention, the method of the invention results in a percentage reduction in the halo area of ​​at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, or about 100%. In one embodiment of the invention, the method of the invention results in a percentage reduction in the halo area of ​​between about 5% and about 95%, between about 15% and about 85%, between about 25% and about 75%, between about 35% and about 65%, and between about 45% and about 55%.

[0021] The method of the present invention can be carried out using high speed production printing methods known in the art. Preferably, the method of the present invention uses direct printing by stencil / screen or gravure printing methods.

[0022] As shown in Figure 2a, the membrane (10) is overlaid with a stencil (20) on one of the membrane's surfaces (not shown). When the stencil openings (30) are filled with a hardenable composition, topographical features (40) are formed. When the stencil (20) is separated from the membrane (10), the topographical features (40) formed from the hardenable composition remain bonded to the membrane surface (50), as shown in Figure 2b.

[0023] The surface on which the topographical features are formed by the method of the present invention can include any surface suitable for the high speed printing method disclosed herein. In one aspect of the present invention, the surface on which the topographical features are formed is a membrane surface, also referred to as a substrate surface. As used herein, "membrane" means a selective barrier that allows some substances to pass while preventing the passage of other substances. In one aspect of the present invention, the membrane is a filter membrane, i.e., a membrane for filtering substances from a liquid carrier such as water. Filter membranes include reverse osmosis, forward osmosis, microfiltration, ultrafiltration, and nanofiltration membranes. The topographical features can be printed on the active surface of the membrane, or on the non-active surface of the membrane, or both. Devices made according to the present invention can also be used in applications in which energy is produced, such as by reverse electrodialysis or pressure retarded osmosis (e.g., salinity gradient or osmotic electricity generation).

[0024] In one embodiment of the invention, the membrane has a first surface and a second opposing surface. In one embodiment of the invention, the curable composition is deposited in the stencil or screen opening and on the first membrane surface by depositing a single layer of the curable composition to form the topographical feature. In another embodiment of the invention, the curable composition is deposited in the stencil or screen opening and on the first membrane surface by depositing multiple layers of the curable composition to form the topographical feature. In an embodiment of the invention, the topographical feature can be deposited on the first surface (either the feed side or the permeate side) or on both the first surface and the second opposing surface.

[0025] In an embodiment of the present invention, the curable composition bleeds onto the portion of the surface covered by the stencil. When the bleeding curable composition portion hardens, it forms a halo around the topographical feature (as discussed above). Thus, the halo area is a function of the properties of the curable composition (e.g., how easily the curable composition flows), the composition of the film and the stencil, and the nature of the contact of the film surface with the stencil (e.g., whether the film and the stencil are both flat and in uniform contact with each other, and how much pressure is applied to bring the film surface and the stencil into contact).

[0026] As used herein, the term "positive pressure" refers to pressure applied to a surface with a direction away from the pressure source. Positive pressure can therefore be thought of as a pushing force on the surface to which it is applied. As used herein, the term "negative pressure" refers to pressure applied to a surface with a direction toward the pressure source. Negative pressure can therefore be thought of as a pulling force on the surface to which it is applied, such as suction or vacuum.

[0027] In one embodiment of the invention, after the stencil is placed on the first membrane surface, a positive pressure is applied to the second, opposing surface of the membrane to force the first surface into contact with the stencil. This positive pressure thereby creates stronger contact between the first surface and the stencil during deposition of the hardenable composition into the stencil openings, thereby reducing bleeding of the hardenable composition. However, the positive pressure should not be so high as to damage the membrane. In embodiments of the invention, the positive pressure has a magnitude between about 5 psi and about 50 psi, between about 10 psi and about 40 psi, or between about 20 psi and about 30 psi.

[0028] The stencil or screen may be constructed from any useful material that allows the stencil to be adequately sealed to the surface, so as to allow for removal of the stencil from the surface without damaging the surface or disturbing the deposited curable composition, to aid in optimizing bleeding of the curable composition onto the surface portions covered by the stencil. In aspects of the invention, the stencil or screen is made from metal, such as steel, aluminum, stainless steel, polymer-coated metal, ceramic-coated metal, woven metal, composite material, polymer, such as polyester or fluoropolymer, or woven polymer.

[0029] Stencil printing methods use a stencil made from a single sheet of material into which a pattern is cut. The stencil is mounted in a frame, and may also be mounted on a frame with a mesh to provide air tightness, flatness, and resilience. The mesh may be made of any suitable material, such as stainless steel, nylon, plastic, carbon fiber, and the like. The thickness of the stencil is the height of the feature to be printed minus the effects of gravity and physical properties that reduce the height due to certain factors during printing (usually about 20%). The pattern and aperture size (aperture) also determine how much product can be released from a stencil of maximum thickness. Stencils with a low surface energy top surface provide a higher release from the stencil. Wet printing methods are limited to a height of about 20% less than the stencil thickness. Furthermore, in wet printing methods, the stencil thickness is limited to about 0.010 inches. For stencil thicknesses greater than about 0.010 inches, the curable composition will not be released from the stencil. However, in the pre-cured method using a stencil as a mold, the product is pre-cured to the thickness of the stencil, which may have a higher thickness than that used in the wet printing method. For example, in the pre-cured method, the stencil may have a thickness of 0.050 inches in height. Thus, the curable composition is not fully cured, and due to the low surface energy coating of the stencil, the features (geometry) may be released from the voids of the stencil. After the curable composition is fully cured, the height of the features will be approximately the same as the height of the stencil.

[0030] In the screen printing method, a stainless steel mesh, or a polyester or Nylon screen is used, having an emulsion formed thereon that covers a portion of the screen or mesh, exposing the pattern into which the curable composition is deposited. The thickness of the print is dependent on the thickness of the mesh, the open area of ​​the mesh, and the thickness of the emulsion build-up. The thickness is also affected by printer variables such as squeegee pressure and hardness tester, angle of attack, speed, and snap-off distance. The viscosity of the printing material can vary from low to high depending on the application requirements.

[0031] The openings or voids in the stencil or screen pattern of the present invention can take any shape or combination of shapes required to produce a desired shape for the topographical feature. For example, the openings can be formed as circles, ellipses, arcs, squares, rectangles, diamonds, pentagons, hexagons, stars, chevrons, or any combination thereof. Such opening shapes produce three-dimensional topographical features having a cross section corresponding to the shape of the opening and having heights and aspect ratios described herein. For example, circular openings produce cylindrical topographical features such as the topographical feature pattern for water desalination or brackish water filtration shown in FIG. 1. The depth of the stencil determines the height of the topographical feature and is selected to match the desired height according to the desired aspect ratio. For example, the height can be about 0.005 to about 0.04 inches, desirably about 0.010 to about 0.025 inches, and more preferably about 0.012 to about 0.015 inches.

[0032] In one aspect of the invention, the topographical features are substantially free of sharp edges after the formation and removal of the stencil. For example, the edges of the openings in the stencil may be completely free of sharp edges, such that the deposited curable composition does not have sharp edges. Furthermore, when the stencil or screen is removed, the curable composition does not pull up along with the stencil or screen causing sharp edges on the topographical features. In essence, the curable composition sinks enough to maintain a curved or flat surface, but the curable composition does not sink so much that it loses aspect ratio. Furthermore, the stencil coating is selected to have a surface energy low enough to avoid the curable composition being pulled when the stencil or screen is removed. Thus, the topographical features are typically smooth or flat without sharp edges that could damage the bonding layer of the film during operation.

[0033] Generally, the curable composition of the present invention can be deposited in the stencil opening and on the membrane surface, and once deposited and left to stand, can maintain its shape during removal of the stencil and during curing.In an embodiment of the present invention, the curable composition has a curing speed of about 5 seconds or less.In an embodiment of the present invention, the curable composition has a curing speed of about 4 seconds or less, about 3 seconds or less, about 2 seconds or less, about 1 second or less.

[0034] In one embodiment of the present invention, the curable composition comprises 10s -1 The viscosity may be determined using known methods, such as a cone and plate rheometer, a parallel plate rheometer, or a rotational viscometer such as a Brookfield viscometer.

[0035] In an embodiment of the invention, the curable composition is photocurable or photocurable, i.e., curable using light such as visible or ultraviolet (UV) light. In an embodiment of the invention, the curable composition can be cured using a light source such as a light bulb or LED that produces visible or UV light. In one embodiment of the invention, the curable composition is at least partially cured by exposing the side of the film that does not have topographical features to a light source, typically a visible light source.

[0036] In another aspect of the invention, in addition to some or all of the above features, a system is provided that further includes several processing stations, as depicted in FIG. 4. As shown in FIG. 4, a supply of membrane material 170 (without features (geometry) provided thereon, also referred to herein as substrate) is fed by a series of rollers 171 to an application station 172, where topographical features are applied via a dispenser 180. The membrane may be selected from reverse osmosis membranes, forward osmosis membranes, microfiltration membranes, ultrafiltration membranes, and nanofiltration membranes. The membrane travels under a template 190, positioned by the rollers 171, and aligned to a table 192, whereby the curable composition can be deposited on the membrane using the template that controls the positioning of the topographical features to be formed on the membrane. The table and roller system also allows for better control of the application of the curable composition, thereby adjusting the tension on the membrane to form the topographical features. The template (stencil) allows the adhesive to reach the intended areas of the membrane, which is determined by the pattern of openings in the template. The topographical features are applied to the membrane via a hardenable composition dispenser 180, shown (above) with the template (stencil), which applies a desired amount of hardenable composition to designated template openings (openings exposing the underlying membrane portions) to create the intended topographical feature pattern on the membrane. Thus, the pattern of features is controlled by the template. The size and shape of the features can be varied as discussed in various sections of this disclosure and can be tailored to provide the intended product and application of the product. The dispensing device 180 can include a valve and squeegee wiping device (not shown) to provide height consistency and remove unwanted hardenable composition from the template (stencil) areas. The pattern of features formed may be random or regular as desired to suit a particular product and / or application, and may include a number of shapes including, but not limited to, circles, ellipses, arcs, squares, rectangles, diamonds, pentagons, hexagons, stars, chevrons, and combinations thereof.

[0037] The template 190, also referred to herein as a stencil, can be made from a variety of materials, including, but not limited to, steel, aluminum, stainless steel, polymer-coated metal, ceramic-coated metal, woven metal, composite materials, polymers such as polyester or fluoropolymers, woven polymers, and combinations thereof.

[0038] Station 172 of FIG. 4 further includes a vacuum or pressure table 192, which serves as a first support for the film, which is a positioning device and serves to hold the film stationary while simultaneously applying features to the film. The vacuum and / or pressure table provides a back pressure that seals the substrate against the stencil to prevent adhesive from leaking beyond the desired pattern. The vacuum and / or pressure table provides a vacuum that holds the substrate down so that a removal force can be applied to remove the pre-cured features from the stencil.

[0039] Station 172 also includes a light source 200 for partially curing or solidifying the hardenable composition, e.g., sufficiently fixing topographical features formed by the hardenable composition, to prevent substantial deformation or dimensional change, thereby allowing further processing without loss of the intended topography, size, or shape. As described herein in this disclosure, various light sources can be used for partial curing, the selection of which depends on the type of cure system present in the hardenable composition. For example, if the hardenable composition includes a cure system that responds to UV light, a UV light source is used. If the cure system responds to multiple types of light sources, partial curing can be achieved using one or more different light sources, alone or in combination.

[0040] The irradiation time for partial curing can vary depending on several factors, including light intensity, distance of the light from the curable composition, and temperature conditions. Generally, the process of applying the curable composition is carried out at room temperature (RT), but small variations in temperature generally do not have a substantial effect on the application and partial curing of the topographical features formed from the adhesive composition.

[0041] The partial curing device 200 and the full curing device 212 can emit the same or different wavelengths of light energy as disclosed herein.

[0042] To allow for partial curing of the hardenable composition, the support table 192 desirably allows sufficient light to pass therethrough so that the light can reach the hardenable composition and sufficiently set the composition, as described herein. The table 192 may be translucent or transparent to allow easy transmission of light therethrough.

[0043] The system of FIG. 4 further includes a full curing station 210, where the applied curable composition is fully cured on the film by one or more additional light sources 212. The fully cured topographically characterized film (i.e., topographically characterized film) formed on the station can be further processed, for example, by cutting the film to a desired length or width at a cutting station 214, and then collected, for example, as shown at 220. The topographically characterized film thus formed can then be further stored for future use in a desired filtration device. Or the system described herein can be integrated into a continuous process, whereby a particular filtration device is formed. For example, a water filtration device can be formed by spirally wrapping the topographically characterized film around a core tubular member, as is conventional in the art for such products.

[0044] In another aspect of the invention, the hardenable composition can be cured to a solid state after removal of the stencil or screen. In another aspect of the invention, the hardenable composition can be cured to a solid state (e.g., fully cured) before removal of the stencil or screen.

[0045] In yet another aspect of the invention, the hardenable composition can be partially cured prior to removal of the stencil. As used herein, "partially cured" means hardening the hardenable composition sufficiently to retain the shape of its topographical features, but insufficient to cause adhesion with the stencil or screen. In one aspect of the invention, the hardenable composition can be exposed to conditions to partially cure the hardenable composition. In an aspect of the invention, this partial cure can be caused by exposing the side of the film lacking the topographical features to a visible light source. In another aspect of the invention, this partial cure can be caused by exposing the side of the film lacking the topographical features to about 50 mJ / cm2. 2 ~Approx. 350mJ / cm 2 , about 510mJ / cm 2 ~Approx. 300mJ / cm 2 , or about 125 mJ / cm 2 ~about 250mJ / cm 2 In another embodiment of the invention, the light used to effect this partial cure has a wavelength of about 405 nm.

[0046] In another embodiment of the invention, the partially cured hardenable composition is further exposed to conditions to harden the hardenable composition to a solid state. In a further embodiment of the invention, after removal of the stencil or screen, the partially cured hardenable composition can be cured to a solid state, desirably a fully cured state, by exposing the composition to a UV or visible light source as described above and further discussed with respect to FIG. 4. In another embodiment of the invention, this full cure is achieved by exposing the hardenable composition to about 5 J / cm. 2 ~About 11J / cm 2 , about 6J / cm 2~about 10J / cm 2 , or about 7 J / cm 2 ~About 9J / cm 2 In another embodiment of the invention, the light used to effect this full cure has a wavelength of about 405 nm.

[0047] In this aspect of the invention, the viscosity of the hardenable composition can be increased prior to removal of the stencil or screen to help maintain the shape of the topographical features during removal of the stencil. In some cases, this partial cure causes the hardenable composition to gel or partially harden to a semi-solid state. As previously discussed, the stencil or screen can be made from a coated metal that provides a low surface energy that allows for release (liberation) of the hardenable composition from the stencil due to the limited adhesion created to the film during pre-cure.

[0048] This partial curing method allows for dramatically improved aspect ratios over wet printing, as any desired height (i.e., 0.005-0.040 inches) can be achieved in a single step instead of requiring the deposition of multiple layers to reach the required height.

[0049] In a further aspect of the present invention, there is provided a photocurable composition comprising: a photocurable component comprising a backbone having residues derived from (meth)acrylate, epoxy, polyisobutylene (PIB), polyurethane (PU), polyolefin (PO), ethyl vinyl acetate (EVA), polyamide (PA), and combinations thereof; and a photocurable moiety; a cure system; and a rheology modifying component present in an amount of about 2% to about 50% by weight of the total curable composition, the curable composition being capable of being photocured for 10 s. -1 The curable composition has a viscosity of 10,000 to 500,000 centipoise (cP) at 100° C., and a thixotropic index (TI) (1s -1 Viscosity at / 10s -1 (viscosity at

[0050] For example, materials used to create such polymer backbones include (meth)acrylic monomers such as (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, and the like. (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, phenyl (meth)acrylate, tolyl (meth)acrylate, benzyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, stearyl (meth)acrylate, glycidyl (meth)acrylate, 2-aminoethyl (meth)acrylate acrylate, γ-(methacryloyloxypropyl)trimethoxysilane, (meth)acrylic acid-ethylene oxide adduct, trifluoromethylmethyl (meth)acrylate, 2-trifluoromethylethyl (meth)acrylate, 2-perfluoroethylethyl (meth)acrylate, 2-perfluoroethyl-2-perfluorobutylethyl (meth)acrylate, 2-perfluoroethyl (meth)acrylate, perfluoromethyl (meth)acrylate, diperfluoromethylmethyl (meth)acrylate, 2-perfluoromethyl-2-perfluoroethyl perfluoroethylmethyl (meth)acrylate, 2-perfluorohexylethyl (meth)acrylate, 2-perfluorodecylethyl (meth)acrylate, 2-perfluorohexadecylethyl (meth)acrylate, etc.; styrene monomers, such as styrene, vinyltoluene, α-methylstyrene, chlorostyrene, styrenesulfonic acid and its salts; fluorine-containing vinyl monomers, such as perfluoroethylene, perfluoropropylene, vinylidene fluoride, etc.; silicon-containing vinyl monomers, such as vinyltrimethoxysilane, vinyltriethoxysilane, etc.;Included are maleic anhydride, maleic acid, mono- and di-alkyl esters of maleic acid; fumaric acid, and mono- and di-alkyl esters of fumaric acid; maleimide monomers such as maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide, hexylmaleimide, octylmaleimide, dodecylmaleimide, stearylmaleimide, phenylmaleimide, cyclohexylmaleimide, and the like; nitrile-containing vinyl monomers such as acrylonitrile, methacrylonitrile, and the like; amide-containing vinyl monomers such as acrylamide, methacrylamide, and the like; vinyl esters such as vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate, vinyl cinnamate, and the like; alkenes such as ethylene, propylene, and the like; conjugated dienes such as butadiene, isoprene, and the like; vinyl chloride, vinylidene chloride, allyl chloride, and allyl alcohol. Each of these monomers can be used alone, or a plurality of them can be copolymerized.;

[0051] Suitable examples of epoxies useful in creating such scaffolds include, but are not limited to, bisphenol A epoxies, bisphenol F epoxies, novolac epoxies, aliphatic epoxies, glycidyl amine epoxies, and cycloaliphatic epoxies.

[0052] Suitable examples of polyisobutylene (PIB) useful for making such scaffolds include, but are not limited to, polyisobutylene diacrylates, as described in U.S. Patent Application Publication No. 2014 / 0243444A1.

[0053] Suitable examples of polyurethanes (PU) useful for making such scaffolds include, but are not limited to, polyester urethane acrylates and polyether urethane acrylates.

[0054] Suitable examples of polyolefins (PO) useful for making such scaffolds include, but are not limited to, UC-102M and UC-203M manufactured by Kuraray, polyethyl acrylate and polybutyl acrylate as described in U.S. Pat. Nos. 7,781,494 and 6,720,395.

[0055] The photocurable moieties can be any chemical moieties or groups, such as vinyl groups, (meth)acrylates, and epoxy groups, that are attached to the polymer backbone, desirably, but not necessarily, the ends of the polymer backbone, and that cure via a crosslinking reaction upon exposure to actinic radiation, such as LED, visible light, or UV light.

[0056] In one embodiment of the invention, the light curable component includes a material selected from the group consisting of urethane (meth)acrylates and (meth)acrylates.

[0057] The cure system includes at least one cure initiator and, optionally, a sensitizing compound and / or an electron donor capable of absorbing radiation in the appropriate range of about 300-1000 nm. The cure initiator (or photoinitiator) may be a UV initiator, a visible initiator, or a combination of a UV initiator and a visible initiator.

[0058] A variety of UV initiators can be used, which are generally effective in the range of 200-400 nm, particularly in the portion of the spectrum adjacent to and just beyond the invisible portion of the visible, e.g., >200 nm to about 390 nm.

[0059] Initiators useful in the present invention that initiate and induce cure of the (meth)acrylic functionalized curable component in response to UV radiation include, but are not limited to, benzophenone and substituted benzophenones, acetophenone and substituted acetophenones, benzoin and its alkyl esters, xanthone and substituted xanthones, phosphine oxides, diethoxy-acetophenone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, diethoxyxanthone, chloro-thio-xanthone, N-methyldiethanol-amine-benzophenone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone, and mixtures thereof.

[0060] Examples of such initiators include those commercially available from IGM Resins under the trademarks "IRGACURE" and "DAROCUR", specifically "IRGACURE" 184 (1-hydroxycyclohexyl phenyl ketone), 907 (2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one), 369 (2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanone), 500 (a combination of 1-hydroxycyclohexyl phenyl ketone and benzophenone), 651 (2,2-dimethoxy-2-phenylacetophenone), 1700 (bis(2,6-dimethoxybenzene)), and 1800 (bis(2,6-dimethoxyphenyl)-1-butanone). Bis(2,4,4-trimethylpentyl)phosphine oxide and 2-hydroxy-2-methyl-1-phenyl-propan-1-one) and 819 [bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide], as well as "DAROCUR" 1173 (2-hydroxy-2-methyl-1-phenyl-1-propane) and 4265 (2,4,6-trimethylbenzoyldiphenyl-phosphine oxide and 2-hydroxy-2-methyl-1-phenyl-propan-1-one), and 2,4,6-trimethylbenzoyldiphenylphosphine oxide (commercially available as LUCIRIN TPO from BASF Corp.). Of course, combinations of these materials can also be used herein. It will be appreciated that some of these photoinitiators classified herein as UV photoinitiators have tailing absorption in the visible range and thus straddle the line between UV and visible light curing initiators, but are nevertheless understood to be included herein as part of the present invention.

[0061] Initiators suitable for use in the present invention that initiate and induce cure in response to visible light include, but are not limited to, camphorquinone peroxyester initiators, 9-fluorene carboxylic acid peroxyesters, visible light [blue] photoinitiators, d1-camphorquinone, "IRGACURE" 784DC (a substituted titanocene-based photoinitiator), and combinations thereof.

[0062] Other suitable photoinitiator systems include those disclosed in each of the following patent documents or publications, each of which is incorporated herein by reference in its entirety: U.S. Patent No. 4,505,793 to Tamoto et al., incorporated herein by reference, discloses a photoinitiator comprising a combination of a 3-keto substituted coumarin compound and an active halogen compound. Several exemplary compounds are disclosed. Such photoinitiators are cured by exposure to light having a wavelength in the range of between about 180 nm and 600 nm. U.S. Patent No. 4,258,123 to Nagashima et al., incorporated herein by reference, discloses a photosensitive resin composition comprising an initiator component that generates free radicals upon exposure to actinic light. Such components include various triazine compounds, as more fully described in the disclosure.

[0063] Cationic photoinitiators for epoxy curing include diaryliodonium salts, triarylsulfonium salts, and phenacylsulfonium salts. Commercially available cationic photoinitiators include Omnicat 432 (triarylsulfonium hexafluorophosphate salt), Omnicat 440 (4,4'-dimethyl-diphenyliodonium hexafluorophosphate), and Omnicat 550 (10-biphenyl-4-yl-2-isopropyl-9-oxo-9H-thioxanthen-10-ium hexafluorophosphate).

[0064] Further useful components are disclosed in the following documents, which are incorporated herein by reference: European Patent EP0 369 645A1 discloses a three-part photoinitiator system including a trihalomethyl-substituted-s-triazine, a sensitizing compound capable of absorbing radiation in the range of about 300-1000 nm, and an electron donor. Exemplary sensitizing compounds are disclosed including ketones, coumarin dyes, xanthene dyes, 3H-xanthen-3-one dyes, acridine dyes, thiazole dyes, thiazine dyes, oxazine dyes, azine dyes, aminoketone dyes, methane and polymethine dyes, porphyrins, aromatic polycyclic hydrocarbons, p-substituted aminostyryl ketone compounds, aminotriarylmethanes, merocyanines, squarylium dyes, and pyridinium dyes. Exemplary donors are also disclosed, including amines, amides, ethers, ureas, ferrocenes, sulfinic acids and their salts, ferrocyanide salts, ascorbic acid and its salts, dithiocarbamic acids and its salts, xanthates, ethylenediaminetetraacetic acid salts, and tetraphenylboronic acid salts. Such initiators are sensitive to both UV and visible light.

[0065] Further useful components are disclosed in European Patent EP 0 563 925 A1, where photoinitiators are provided that include sensitizer compounds capable of absorbing radiation in the range of about 250-1000 nm and 2-aryl-4,6-bis(trichloromethyl)-1,3,5-triazines. Exemplary sensitizer compounds disclosed include cyanine dyes, merocyanine dyes, coumarin dyes, ketocoumarin dyes, (thio)xanthene dyes, acridine dyes, thiazole dyes, thiazine dyes, oxazine dyes, azine dyes, aminoketone dyes, squarylium dyes, pyridinium dyes, (thia)pyrylium dyes, porphyrin dyes, triarylmethane dyes, (poly)methane dyes, aminostyryl compounds, and aromatic polycyclic hydrocarbons. These photoinitiators are sensitive to UV and visible light.

[0066] U.S. Patent No. 5,395,862 to Neckers et al., incorporated herein by reference, discloses fluorone photoinitiators that are sensitive to visible light. Such fluorone initiator systems also include coinitiators that can accept electrons from excited fluorone species. Exemplary coinitiators are disclosed that include onium salts, nitrohalomethanes, and diazosulfones. U.S. Patent No. 5,451,343 to Neckers et al., incorporated herein by reference, discloses fluorone and pyronine-Y derivatives as initiators that absorb light at wavelengths greater than 350 nm. U.S. Patent No. 5,545,676 to Palazzotto et al., incorporated herein by reference, discloses a three-part photoinitiator system that cures under UV or visible light. The three-part system includes an aryl iodonium salt, a sensitizing compound, and an electron donor. Exemplary iodonium salts include diphenyl iodonium salts. Exemplary sensitizers and electron donors for use in the three-part system are also disclosed. Additionally, the sensitizer can absorb light in the range of about 300 to 1000 nm.

[0067] The aforementioned initiators are for illustrative purposes only and are in no way meant to limit the initiators that may be used in the present invention.

[0068] The initiator may be used in an amount of from about 0.1% to about 10% by weight of the total composition. More desirably, the initiator is present in an amount of from 0.5% to about 5% by weight of the total composition.

[0069] As used herein, "rheology modifying component" refers to a composition or compound that changes the rheological properties, such as viscosity or flow, of the curable composition. Suitable rheology modifying components include organic and inorganic. Inorganic ones include silica, silicates, alumina, asbestos, barium sulfate, calcium carbonate, calcium fluoride, carbon black, clay, diatomaceous earth, feldspar, ferromagnetic materials, fly ash, glass fiber, gypsum, jute fiber, kaolin, lingnocellulosic, magnesium hydroxide, mica, microcrystalline cellulose, powdered metals, quartz, starch, talc, titanium dioxide, wood flour, wood fiber, and combinations thereof. Organic rheology modifiers include thermoplastic polymers (poymers), such as polyvinyl acetate, polyolefins, nylon fibers. In one embodiment of the present invention, the rheology modifying component is present in an amount of about 2% to about 80% by weight based on the total weight of the curable composition. In another embodiment of the invention, the rheology modifying component is present in an amount of about 4% to about 50% by weight based on the total weight of the hardenable composition. In other embodiments of the invention, the rheology modifying component is present in an amount of about 5%, or about 10%, or about 15%, or about 20%, or about 25%, or about 30%, or about 35%, or about 45%, or about 55%, or about 60%, or about 65%, or about 75% by weight based on the total weight of the hardenable composition.

[0070] Optional additives, such as, but not limited to, stabilizers, inhibitors, oxygen scavengers, fillers, dyes, colorants, pigments, adhesion promoters, plasticizers, toughening agents, toughening agents, fluorescent agents, wetting agents, antioxidants, and combinations thereof, may also be included in the compositions of the present invention.

[0071] In one embodiment of the invention, the curable composition, after curing, loses less than about 5% by weight when immersed in an aqueous solution having a pH range of about 0.5 to about 13.5 at a temperature of about 25° C. to about 90° C. for a period of no more than 6 weeks.

[0072] In another aspect of the invention, the curable composition is capable of forming and maintaining topographical surface features having an aspect ratio (height / width) of greater than about 0.5 prior to curing.

[0073] The topographical features formed on the membrane surface by the method of the present invention have physical properties that make them suitable for providing spacing between overlying layers of membranes. For example, the topographical features can provide suitable spacing between layers of spiral wound reverse osmosis filtration membranes to optimize operation, cleaning, and life of reverse osmosis membrane elements that use membranes having these topographical features. Furthermore, the topographical features are typically smooth or flat, without sharp edges that could damage the bonding layers of the membrane during operation.

[0074] In one embodiment of the invention, the aspect ratio of the topographical features is greater than 0.50 or greater than about 0.70. A combination of aspect ratios can be used in the patterns to provide specific spacing configurations between layers of membranes or other surfaces in the osmotic devices of the invention. As used herein, the term "aspect ratio" refers to the ratio of the height of a topographical feature to the width of the topographical feature.

[0075] In one embodiment of the invention, the height of the topographical feature is from about 0.001 to about 0.05 inches. In another embodiment of the invention, the height of the topographical feature is from about 0.01 to about 0.04 inches. The height of the topographical feature is the distance from the base of the topographical feature (on the membrane surface) to the point on the topographical feature that is vertically furthest from the membrane surface.

[0076] In one aspect of the invention, the width of a topographical feature is defined as the smallest dimension of the footprint of the topographical feature on the film surface, where the footprint is the covered area or region on the substrate surface.

[0077] In one embodiment of the invention, the pattern of topographical features is about 0.5 mm 2In another embodiment of the invention, the pattern of topographical features is formed on the membrane surface at a rate of about 1 m / min or faster. 2 / min or faster, or approximately 2 m 2 / min or faster on the membrane surface.

[0078] The printing speed of the topographical features of the present invention can also be optimized since the desired height can be achieved while depositing only a single layer of curable composition without detrimental effects on aspect ratio and overall film efficiency (as opposed to, for example, having to coat and cure 10-20 layers of UV ink). Furthermore, this single layer deposition is also done simultaneously across the entire 40 inch width of the film. Thus, the time to print a single leaf is the linear speed of traversing the length of the leaf (also 40 inches). Thus, there is no need to travel in both the X and Y directions with multiple passes. In essence, there is no need to deposit multiple layers of curable composition to achieve the desired height on the film before curing or pre-curing. This confers a significant speed advantage over other technologies. For example, UV inks deposit a maximum height of 0.001 inches per pass. The present method can deposit 10 times that, i.e., 0.010 inches per pass, while the pre-curing method can deposit 40 times that, i.e., 0.040 inches per pass. The method of the present invention is also capable of depositing less than the maximum height in a single pass for complete flexibility in topographic feature design.

[0079] In other aspects of the invention, positive or negative pressure is applied during one or more of the overall methods of forming topographical features on a membrane surface. In an aspect of the invention, the overall method of forming topographical features on a membrane surface includes: A) the membrane is provided on a support, e.g., a support table 192, with its second surface facing downwards and in contact with the support; B) the membrane is aligned under a stencil; C) the membrane is flattened onto a support; D) a stencil is lowered onto a first (upward) surface of the membrane; E) depositing a hardenable composition from a composition dispenser 180 into the stencil openings and onto the first surface to form topographical features; F) the curable composition is partially cured using a light source 180; G) the stencil is removed from the first surface of the membrane; H) the curable composition is cured in station 210 using a light source (energy source) 220 to a solid state, preferably a fully cured state; I) The membrane is removed from the support. In an embodiment of the invention, step H) can occur simultaneously with step I). For example, curing can occur using a static light source, and the film passes through the light source during removal.

[0080] In one embodiment of the invention, a positive pressure is applied to the second surface of the membrane during steps E) and F) to bring the first surface into contact with the stencil. As previously discussed, this positive pressure thereby creates stronger contact between the first surface and the stencil during deposition of the hardenable composition into the stencil openings, thereby reducing bleeding of the hardenable composition. However, the positive pressure should not be so high as to damage the membrane. In an embodiment of the invention, the positive pressure during steps E) and F) has a magnitude between about 5 psi and about 50 psi, between about 10 psi and about 40 psi, or between about 20 psi and about 30 psi.

[0081] In one embodiment of the invention, a positive pressure can be applied to the second surface of the membrane during at least a portion of one or both of steps A) and B). In another embodiment of the invention, a positive pressure can be applied to the second surface of the membrane during at least a portion of one or both of steps H) and I). Thus, the membrane can be floated by an airflow device (not shown) during its removal from the support. The positive pressure floats the membrane above the support, allowing for gentle feeding and alignment of the membrane onto the support. As used herein, the term "floating" means lifting the membrane so as to reduce or eliminate contact between the membrane and the support. In a further embodiment of the invention, the magnitude of the positive pressure required to float the membrane is about 10 psi or less, preferably 5 psi.

[0082] In one embodiment of the invention, negative pressure can be applied to the second surface of the membrane by a suction or vacuum device (not shown) during at least a portion of one or both of steps C) and D). Thus, the membrane can be held against the support to maintain its flatness and position during the lowering of the stencil, while avoiding damage often associated with physical constraints of membrane movement. In another embodiment of the invention, negative pressure is applied to the second surface of the membrane during at least a portion of step G). Thus, the membrane can be held against the support while the stencil is lifted from the first surface of the membrane and removed. The negative pressure allows for removal of the stencil without the need for pulling forces on the membrane, which often lead to damage. In a further embodiment of the invention, the magnitude of the negative pressure required to maintain the position of the membrane on the support is about 100 Torr or less, preferably 50 Torr.

[0083] Another method of forming topographical features on a membrane surface in accordance with the present invention includes the steps of providing an apparatus with a support for supporting a membrane having a first surface and a second opposing surface and capable of creating positive and negative pressure on a contacted surface of the membrane, contacting the second surface of the membrane with the support, providing a stencil on the first surface of the membrane, the stencil having an opening exposing the first surface for receiving a hardenable composition, applying positive pressure to the second surface to contact the first surface with the stencil, and depositing one or more layers of the hardenable composition within the stencil opening and the second surface. and depositing a curable composition on the first surface to form a topographical feature, the openings defining the approximate shape and size of the topographical feature; exposing the curable composition to conditions to partially cure the curable composition sufficient to retain the topographical feature but insufficient to cause adhesion to the stencil; and applying negative pressure to the second surface to separate the film and the stencil without disturbing the partially cured topographical feature, the positive pressure being sufficient to reduce a halo area around the topographical feature by at least about 10%.

[0084] In general, the foregoing description is provided for purposes of illustration and demonstration, and the present invention is not necessarily limited thereto. Rather, those skilled in the art will recognize that further modifications and adaptations to particular environments are within the scope of the invention as shown and described herein and the claims appended hereto. EXAMPLES

[0085] Comparative topographical features were fabricated using the previous process without the application of positive pressure during deposition and partial curing of the curable composition. As shown in FIG. 3a, this method, which is not the present invention, resulted in a noticeable halo (130) around the topographical feature (120) on the membrane surface (110). This halo was larger than the area (A tf ) compared to about 0.42 halo area (A h ) was measured.

[0086] Topographical features were fabricated using the previous method, applying a positive pressure of 30 psi during deposition and partial curing of the curable composition, and using the process of the present invention. As shown in FIG. 3b, this method of the present invention resulted in a nearly undetectable halo (160) around the topographical feature (150) on the membrane surface (140). This halo was approximately 100% larger than the area (A tf ) compared to about 0.25 halo area (A h ) was measured.

[0087] In view of the above, the method of the present invention reduced the halo area percentage by approximately 40.5%.

Claims

1. 1. A method for forming topographical features on a membrane surface, comprising: a. providing a stencil over a first surface of a membrane, the stencil having an opening exposing the first surface that receives a hardenable composition; b. applying a positive pressure to a second, opposing surface of the membrane to bring said first surface into contact with a stencil; c. depositing one or more layers of a hardenable composition into the stencil openings and on the first surface to form a topographical feature, the openings defining the approximate shape and size of the topographical feature; d. exposing the hardenable composition to conditions to partially cure the composition sufficient to retain its topographical features, but insufficient to cause adhesion to the stencil; e. applying negative pressure to the second surface to separate the membrane and the stencil without disturbing the partially cured topographical features; wherein the positive pressure is sufficient to reduce a halo area around the topographical feature by at least about 25%. method.

2. The method of claim 1 , wherein the conditions for partially curing the curable composition include exposing the film to a light source.

3. The method of claim 2 , wherein light from a light source is directed onto the second surface.

4. 13. The method of claim 1, further comprising the step of exposing the partially cured topographical features to conditions to harden the curable composition to a solid state.

5. The method of claim 4 , wherein the conditions for curing the curable composition to a solid state include exposing the film to a light source.

6. The method of claim 1 , wherein the depositing step comprises depositing two or more layers of the curable composition in the stencil openings and on the first surface.

7. The method of claim 1 , wherein the positive pressure is sufficient to reduce a halo area around the topographical feature by at least about 40%.

8. 1. A method for forming topographical features on a membrane surface, comprising: a. providing an apparatus comprising a support capable of supporting a membrane having a first surface and a second opposing surface and creating positive and negative pressure on a contacting surface of the membrane; b. contacting a second surface of the membrane with a support; c. providing a stencil on the first surface of the film, the stencil having an opening exposing the first surface that receives a hardenable composition; d. applying a positive pressure to the second surface to bring the first surface into contact with a stencil; e. depositing one or more layers of a hardenable composition into the stencil openings and on the first surface to form a topographical feature, the openings defining the approximate shape and size of the topographical feature; f. exposing the hardenable composition to conditions to partially cure the composition sufficient to retain its topographical features, but insufficient to cause adhesion to the stencil; g. applying negative pressure to the second surface to separate the membrane and stencil without disturbing the partially cured topographical features; wherein the positive pressure is sufficient to reduce a halo area around the topographical feature by at least about 25%. method.

9. The method of claim 8 , wherein the conditions for partially curing the curable composition include exposing the film to a light source.

10. The method of claim 9 , wherein light from a light source is directed onto the second surface.

11. 10. The method of claim 8, further comprising exposing the partially cured topographical features to conditions to harden the curable composition to a solid state.

12. The method of claim 11 , wherein the conditions for curing the curable composition to a solid state include exposing the film to a light source.

13. The method of claim 8 further comprising removing the membrane from the support.

14. The method of claim 13 , wherein positive pressure is applied to the second surface during removal of the membrane from the support.

15. 14. The method of claim 13, wherein step h. is performed before, during, or after removing the membrane from the support.

16. The method of claim 8 , wherein during the step of contacting the second surface of the membrane with the support, a positive pressure is applied to the second surface.

17. The method of claim 8 , wherein negative pressure is applied to the second surface after the step of placing the membrane on the support and during the step of providing the stencil over the first surface.

18. The method of claim 8 , wherein the depositing step comprises depositing two or more layers of the curable composition in the stencil openings and on the first surface.

19. The method of claim 8 , wherein the positive pressure is sufficient to reduce a halo area around the topographical feature by at least about 25%.

20. The method of claim 1, wherein the curable composition has a viscosity of 10,000 to 500,000 centipoise at a speed of 10 s −1 and is capable of forming and maintaining topographical surface features having an aspect ratio of greater than 0.5 prior to curing.

21. The method of claim 8, wherein the curable composition has a viscosity of 10,000 to 500,000 centipoise at a speed of 10 s −1 and is capable of forming and maintaining topographical surface features having an aspect ratio of greater than 0.5 prior to curing.

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