HK1167361B - Imparting texture to cured powder coatings - Google Patents

Description

Imparting texture to cured powder coatings

Background

Powder coating techniques involve applying a coating of a thermoplastic or thermosetting polymer (e.g., polyamide, polyester, polyolefin, polyurethane, acrylic, fluoropolymer, or epoxy) powder to a substrate to form a continuous film by coagulating the polymer particles at a temperature above their melting point. In the case of thermosetting polymers, the powder is also cured during the setting phase, i.e. the polymerized powder. Curing of thermosetting powders is typically initiated by heat or exposure to radiation, such as with Ultraviolet (UV) light.

Few techniques are known for applying surface textures to powder coated substrates. Us patent 6,238,750, for example, discloses certain techniques which are said to apply a smoothing or texture to a powder coated surface by pressing the surface with a "flexibility limiting film" or "engraved or etched lithographic pattern on the pressing surface". Certain industrial processes impart a rough texture to powder coatings by controlling the coating formulation, for example by using powders of various particle sizes and melting temperatures in powder coating formulations.

Disclosure of Invention

Methods of imparting texture to a cured powder coated surface are provided. These methods include providing a substrate having a surface with a cured powder coating, and heating the cured powder coating to a temperature above the Tg of the cured powder coating. The cured powder coating is then textured, for example under pressure, using a release medium having a repetitive surface. Finally, the release medium is removed from the powder coating.

In addition, a method of applying a textured coating to a substrate includes applying a dry free-flowing powder of a curable material to the substrate, forming a powder layer, heating the powder layer sufficiently to cause the powder to melt and form a uniform layer, and curing the uniform layer to form a cured powder coating on the substrate. The cured powder coating is then heated to a temperature above the T of the cured powder coating_gAnd imparting texture to the cured powder coating, for example under pressure, using a release medium having a repetitive surface. Finally, the release medium is removed from the powder coating.

Drawings

FIG. 1 is a schematic diagram showing texturing of a cured powder coating.

FIG. 2 is a schematic diagram showing a method of texturing a cured powder coating using a nip and a textured release medium in the form of a continuous web (web).

Detailed Description

Methods of imparting texture to cured powder coated surfaces are described. These methods involveProviding a substrate having a cured powder coating on its surface, heating the cured powder coating above its glass transition temperature (T)_g) A release medium having a repeating surface is then used to impart a texture to the cured powder coating. Once the texture has been imparted to the cured powder coating, the release medium is removed. A release medium such as a static press or pressure nip can be used to impart texture to the cured powder coating. These release media can be, for example, an engraved plate, an engraved roll, release paper, release film, or release web.

An example of the process described in this application is shown in figure 1. Referring to fig. 1, to impart texture to the surface 16 of the cured powder coated substrate 10, the surface 16 of the cured powder coated substrate 10 is placed adjacent to the textured surface of the textured release paper 14, both of which are placed between a pair of steel backing plates 13, forming a sandwich structure 12. Heat and pressure are then applied to the sandwich structure 12, i.e., in a press, such as a heated press. Similarly, as long as T above the cured powder coating can be maintained_gWhile applying pressure to the powder coated substrate 10, the powder coated substrate 10 or the entire sandwich structure 12 may be heated prior to applying pressure. A heat source (e.g., a platen, oven, or Infrared (IR) heater) may be used to heat the powder coated substrate 10 prior to pressing the sandwich 12. The release medium may be, for example, a textured release paper 14 as shown in fig. 1 or a release film having a repeating surface. A preferred method of making the isolation media is as follows. Advantageously, the barrier function is established in a barrier medium, and therefore, there is generally no need to modify the powder coating formulation to have barrier properties, or to use release agents that will transfer to the surface of the powder coating.

Various means, such as a static press or pressure nip, may be used to press the release medium against the cured powder coating. If a press is used to apply pressure, the press is closed, the sandwich structure 12 is placed inside, and heat and pressure are applied to impart a texture on the surface of the release medium 14 to the surface 16 of the cured powder coating. The temperature at which the heat-curable powder coating is applied is sufficiently high to heat the cured powder coating to a high temperatureIn the curing of powder coatings_g. The amount of time that the textured release medium 14 is pressed against the surface 16 of the cured powder coating, e.g., press dwell time, depends on a number of factors, such as the heating rate of the heating mechanism and the rate of heat transfer to the cured powder coating, and should be long enough so that the temperature at which the powder coating is cured while pressure is applied is above the T of the cured powder coating_gThereby obtaining a desired texture. If a pressure nip is used to press the release medium against the cured powder coating, heat can be applied to the cured powder coating before the release medium (e.g., release web and cured powder coating) enters the pressure nip. Further, one or more of the rollers of the pressure nip may be heated. As discussed with respect to the static press, the temperature applied to heat cure the powder coating is sufficient to heat the cured powder coating above the T of the cured powder coating_gThe temperature of (2). The temperature of the substrate and the release medium at which the powder coating is cured is higher than the T of the cured powder coating_gWhile passing through the pressure nip. Examples of useful temperatures for heat curing powder coatings that may be used in the methods of the present application include 200 ° F (93 ℃) or greater, 250 ° F (121 ℃) or greater, 300 ° F (149 ℃) or greater, 350 ° F (177 ℃) or greater, 400 ° F (204 ℃) or greater, 450 ° F (232 ℃) or greater, or 500 ° F (260 ℃) or greater, provided that the temperature at which the powder coating is heat cured is greater than the T of the cured powder coating_gAnd (4) finishing.

The textured surface of the release medium is pressed against the surface of the heated cured powder coating at a level sufficient to transfer the texture of the release medium to the cured powder coating. The pressure applied depends on the T after heating above the coating_gThe viscosity of the powder coating is then cured and related to the depth of the texture of the release medium. Examples of pressure ranges useful in the methods of the present application include from about 50p.s.i. (4bar) to about 1400p.s.i. (97bar), from about 100p.s.i. (7bar) to about 1000p.s.i. (69bar), from about 200p.s.i. (14bar) to about 900p.s.i. (62bar), from about 300p.s.i. (21bar) to about 800p.s.i. (55bar), from about 400p.s.i. (28bar) to about 700p.s.i. (48bar), and from about 500p.s.i. (35bar) to about 600p.s.i. (41 bar). An example of a combination of temperature and pressure that can be used in the process of the present application is higher thanT of cured powder coating_gAnd a pressure of from 400p.s.i. (28bar) to 700p.s.i. (48 bar). Other examples of temperatures and pressures that may be used in the methods of the present application are temperatures 255 ° F (124 ℃) (assuming 255 ° F (124 ℃) is higher than the T of the cured powder coating_g) And a pressure of 700p.s.i. (48 bar; press 15 minutes as an exemplary time).

After the texture has been imparted to the surface of the cured powder coating, the release medium is removed from the cured powder coating. The release medium may be removed from the cured coating immediately after the texture has been imparted (and the pressure removed immediately), or the release medium may be left in place and removed at a later time (with optional application or removal of pressure during cooling). If the release medium is in the form of a sheet, the solidified powder coating may be cooled before or after removal of the release medium. For example, if the release medium is in the form of a sheet, the powder coating may be cooled to solidify before the release medium is removed. Alternatively, if the release medium is an engraved roll, for example, the solidified powder coating may be cooled after the engraved roll has completed contact with the solidified powder coating. The solidified powder coating may be cooled, for example, to below the T of the solidified powder coating_g. For example, the cured powder coating can be cooled to 200 ° F (93 ℃), 180 ° F (82 ℃), 160 ° F (71 ℃), 140 ° F (60 ℃), 120 ° F (49 ℃), 100 ° F (38 ℃), 90 ° F (32 ℃), 80 ° F (27 ℃), 70 ° F (21 ℃), 60 ° F (16 ℃), 50 ° F (10 ℃) or 40 ° F (4 ℃), and the release medium removed. A particularly useful cooling temperature for the process of the present application is 70 ° F (21 ℃).

The release medium has a texture on at least one surface thereof that can be imparted to the surface of the cured powder coating (i.e., the side of the release medium with the textured surface is in contact with and pressed against the surface of the cured powder coating). The release medium can be, for example, a plate with a textured surface, a roller with a textured surface, a sheet with a textured surface, or a web with a textured surface. As used herein, a release sheet is intended to include a non-continuous form of paper or film (i.e., sheet) with a textured release coating on the surface. As used herein, a release web is intended to mean a continuous form of paper or film (i.e., a roll) with a textured release coating on the surface. The texture on the surface of the release medium, i.e., "bumps" and "pits", can be formed on the release medium by methods known to those skilled in the art. The texture of the release medium may for example have a surface morphology (topographiy) with features below the wavelength of light.

The texture of the release medium may be imparted to the cured powder coating with low (about 10% to about 40% fidelity), medium (about 40% to about 70% fidelity), high (70% or greater), or 100% fidelity (100% fidelity means that the texture imparted onto the surface of the cured powder coating is an exact inverse of the texture on the surface of the release medium). The fidelity level of the reverse image reproduction of the texture of the release medium depends on a number of factors, such as the structure and composition of the substrate and release coating of the release medium used. An example of a release medium that can produce 100% fidelity is a release medium with an acrylate-containing release coating (see, e.g., the acrylate-containing release coating below).

For the method of the present application, the release medium exhibits satisfactory release properties (which are not necessarily directly related to the reproduced level of fidelity) such that the release medium is easily released from the cured powder coating surface after the texture is imparted at a given level of fidelity. If the desired release properties of the release medium are retained after use (e.g., for release and/or an acceptable level of fidelity), the release medium may be reused. The release medium is also sufficiently resilient to withstand heating of the cured powder coating beyond the cured powder coating T_gI.e. the modulus of the release medium is greater than the modulus of the cured powder coating to be textured. The term modulus as used herein refers to the measure of the deformation a material can withstand under a given stress. Release medium based paper may therefore be used if the release medium, i.e. paper and coating, is resistant to the temperature to which the cured powder coating is heated without deforming when imparting texture.

The release medium may be relief printed (tip printed) with ink or other coating and then transferred to the surface of the cured powder coating using the methods described herein. Relief printing (tip printing) describes U.S. serial No. 11/670,627 filed on 2/2 of 2007, the entire contents of which are incorporated herein. The printing ink is applied to the protruding surface, i.e., the "bumps" of the pattern on the surface of the release medium, using a printing roller. Because only the surface of the protrusions is coated with ink, the "depressions" or depressed areas of the pattern on the surface of the release medium remain free of ink. Typically, relief printing is accomplished by moving a patterned release medium through a printing roll. Relief printing may be performed using any suitable printing technique, such as gravure, flexography, lithography, roll printing, and other well-known printing techniques.

The release medium described herein may comprise a base material, such as paper or film in sheet form or web form, with a release coating. Suitable release coatings for use in the methods of the present application can include acrylated oligomers, monofunctional monomers, and multifunctional monomers for crosslinking. If ultraviolet radiation is used to cure the acrylic functional barrier coating, the barrier coating will also include a photoinitiator as is known in the art. Preferred acrylated oligomers include acrylated urethanes, epoxies, polyesters, acrylics and silicones. The oligomers make a substantial contribution to the final properties of the barrier coating. The skilled person knows how to select the appropriate oligomers to achieve the desired final properties. For example, the desired final properties of the release coatings described herein may include oligomers that provide flexibility and durability. A wide range of acrylated oligomers are commercially available from Cytec Surface Specialties Corporation, such as Ebecryl 6700, 4827, 3200, 1701, and 80, and from Sartomer Company, Inc., such as CN-120, CN-999, and CN-2920.

Useful monofunctional monomers commonly used to form barrier coatings in the methods described herein include acrylic acid, N-vinylpyrrolidone, (ethoxyethoxy) ethyl acrylate, or isodecyl acrylate. The preferred monofunctional monomer is isodecyl acrylate. The monofunctional monomer acts as a diluent, i.e., reduces the viscosity and increases the flexibility of the coating. Other examples of monofunctional monomers include SR-395 and SR-440 from Sartomer company, Inc. and Ebecryl 111 and ODA-N (octyl/decyl acrylate) from Cytec Surface specialties corporation.

The multifunctional monomers used to form the barrier coating of the method of the present application include trimethylolpropane triacrylate (TMPTA), Propoxylated Glyceryl Triacrylate (PGTA), tripropylene glycol diacrylate (TPGDA), and dipropylene glycol diacrylate (DPGDA). Preferred multifunctional monomers are selected from the group consisting of TMPTA, TPGDA and mixtures thereof. Preferred multifunctional monomers act as crosslinking agents. Examples of multifunctional monomers include SR-9020, SR-351, SR-9003 and SR-9209, manufactured by Sartomer Company, Inc., and TMPTA-N, OTA-480 and DPGDA, manufactured by Cytec Surface Specialties Corporation.

By way of example, a composition useful for forming a barrier coating of the claimed method includes (before curing) 20-50% acrylated oligomer, 15-35% monofunctional monomer, and 20-50% multifunctional monomer. The formulation of the release coating composition depends on the final target viscosity and the desired physical properties of the release coating. In some examples, the viscosity is from 0.2 to 5 Pa sec, and in other examples, the viscosity is from 0.3 to 1 Pa sec, as measured at room temperature (21-24 ℃).

The release coating composition may also include other components such as opacifying agents, colorants, slip/spreading agents, antistatic or anti-wear additives. The opacity of the barrier coating can be varied, for example, by the addition of various pigments, such as titanium dioxide, barium sulfate, and calcium carbonate, by the addition of hollow or solid glass beads, or by the addition of incompatible liquids, such as water. The opacity can be adjusted by varying the content of the additives used.

If the release coating is to be uv cured, a photoinitiator or photoinitiator package may be included. Suitable photoinitiators are available from Sartomer Company under the trade designation KTO-46^TM. The initiator may be included in an amount of, for example, 0.5 to 2%.

The cured powder coating material may be any cured powder coating that is cured or crosslinked prior to use in the methods of the present application. For example, a dry free-flowing powder of a curable material may be applied to a substrate to form a powder layer, which is then heated sufficiently to cause the powder to melt and form a cured powder coating on the surface of the substrate. The curable material may include an initiator that is capable of being activated by exposure to radiation. The curable material may also comprise a material capable of absorbing radiation. Radiation curing (e.g., electron beam radiation or ultraviolet radiation) may be used to cure the coating using an initiator that can be activated by exposure to radiation. Electron beam radiation may be advantageously used to penetrate thick coatings. Electron beam irradiation devices are readily available and typically include a transformer capable of stepping (step up) the line voltage and an electron accelerator. Manufacturers of electron beam irradiation devices include Energy Sciences, inc., Wilmington, MA, and pct ingneered Systems, LLC, Davenport, Iowa. Suitable UV curing apparatus are generally available from, for example, Fusion, inc.

Suitable powder coatings for use in the process to which the present application pertains include polyamides, polyesters, polyurethanes, acrylic polymers, polyolefins, fluoropolymers, and epoxy compounds, such as those commercially available from Dupont, Sherwin-Williams, Rohm and Haas, Protech, and others. Other powder coatings may be used, where the curing needs (e.g., T) depend on the particular powder coating formulation_g) Conditions (e.g., time, temperature, and pressure) to impart texture are adjusted. The powder coating may be transparent or pigmented. The properties of the final powder coating, such as chemical resistance and barrier functionality of the cured coating, can be adjusted by the selection of the powder coating chemistry.

A wide range of substrates can be used for the cured powder coatings described herein, so long as the cured powder coatings adhere to the substrate before and after the methods of the present application. For example, the substrate may be a metal, such as aluminum, steel, or other metal, a cellulosic material, such as wood, fiberboard (e.g., medium density fiberboard), paper, plastic, or other material capable of withstanding the conditions of heat curing the powder coating and imparting texture using the release medium. The substrate may also be in the form of a web or sheet/plate. Referring to fig. 2, for example, the substrate may be continuous, such as in the form of a web, or discontinuous, such as a plurality of sheets/plates placed end-to-end on a support mechanism, such as a belt.

Another method of imparting texture to a cured powder coating uses a mechanical construction as shown in fig. 2. In fig. 2, nip 52 is used to provide sufficient pressure to impart a texture from textured surface 54 of release medium 56 onto the surface of cured powder coating 58 (which forms powder coated substrate 62) on substrate 60. Textured release medium 56 is fed from roller 50 to nip 52 along with powder coated substrate 62, which has been previously heated to melt or soften cured powder coating 58. After the heated powder coated substrate 62 and release medium 56 are fed through the nip 52, the powder coating may be cooled. Finally, the textured release medium 56 is removed from the cured powder coating, for example using other nips 64 (which include nip rollers 65) and take-off rollers (take-up rollers) 66, as shown. As another example of cooling, the nip 64 may be quenched as the release medium 56 is removed, thereby cooling the powder coating.

Nip pressures are typically relatively low (e.g., "kiss" pressures) when the temperature of the cured powder coating is raised above its T_gAt the time of the application, the nip pressure is selected based on the properties of the cured powder coating, such as viscosity, to prevent lamination of the powder coating out of its substrate while still allowing the texture on the textured release medium to be imparted onto the surface of the powder coated substrate. Generally, higher viscosity powder coatings and/or deeper patterns may require relatively higher nip pressures.

A textured (e.g., engraved) roller is one example of a repeating surface that can be used to impart a pattern to the cured powder coating using the methods described herein. The textured roller bears a pattern on its surface, the reverse image of which is imparted to the cured powder coated substrate. In fig. 2, for example, rather than using nips 52 and 64 and release medium 56, a textured roller can affect the heated surface of the powder coated substrate 62 to impart texture (a single nip roller can be placed against the textured roller to create pressure that presses the textured roller against the surface of the powder coated substrate 62 that passes between the two rollers). Other types of pattern imparting means may be used. Rotating endless surfaces (endless surfaces), such as rolls, cylinders, or other cylindrical surfaces, are particularly useful in the processes described herein.

In another example of the method described herein, a dry free-flowing powder of a curable material is applied to a substrate to form a powder layer, which is heated sufficiently to cause the powder to melt to form a uniform layer. The uniform layer is then cured (e.g., uv crosslinked) to form a cured powder coating on the substrate if the powder coating has not been thermally cured. The dry, free-flowing powder of the coating material may contain an initiator that can be activated by exposure to radiation and/or a material that can absorb radiation. Once the cured powder coating on the substrate is cooled, the powder coated substrate can be immediately used in the process of the present application or stored for subsequent use. To impart texture to the cured powder coating, the cured powder coating is heated above the T of the cured powder coating_gAnd then imparting a texture using a release medium having a repeating surface. Once the texture has been imparted using the release medium, the release medium is removed from the powder coating.

In another example of the method described herein, a dry free-flowing powder of a curable material is coated onto a substrate to form a powder layer, and the powder layer is heated to a temperature sufficient to cause the powder to melt and form a uniform layer. The uniform layer is then cured to form a cured powder coating on the substrate. Once the powder coating on the substrate is cured, the cured powder coating is heated above the T of the cured powder coating_gAnd imparting texture using a release medium having a repeating surface. Once the texture has been imparted using the release medium, the release medium is removed from the cured textured powder coating.

Examples

Example 1

At 400 ℃ F. (204 ℃ C.) T will be used_gApproximately 156F (69℃.) of a thermosetting polyester powder (BikeBlack, from Dupont (E.I. du Pont DE Nemours and Company; Wilmington, DE)) cured for 15 minutes to form a cured powder coated substrate (using TMA Q400 from TA Instruments (New Castle, DE), T was measured using a modulated TMA experiment at a temperature change of 1 deg.C/minute_g). Once cooled, a textured release paper with an acrylate release coating was used at 700p.s.i. (48bar) IN a hot press (Wabash MPI; Wabash, IN) at 255 ℃ F. (124 ℃ C.) using a setup similar to that shown IN FIG. 1PRU Quartz (sapphire North America; Boston, Mass.) with a basis weight of 224g/m²) As a release medium, the plate was pressed for 15 minutes. The panel was then cooled under pressure to 70 ° F (21 ℃), the pressure removed, and the release medium removed. The inverse of the release medium is formed in the surface of the powder coating with 100% fidelity.

Example 2

At 230 ℃ F. (110 ℃ C.) will use T_gA low energy curable thermoset Powder (polo white, from Protech Powder Inc., Fairfield, NJ) at about 150 ° F (66 ℃) was cured for 15 minutes in a 4 inch x 6 inch x 0.75 inch Medium Density Fiberboard (MDF) coated on both sides to form a cured Powder coated substrate (T @)_gMeasured as in example 1). Once cooled, the panel was pressed for 15 minutes using a setup similar to figure 1, in a 200 ° F (93 ℃), 500p.s.i. (34bar), in a hot press (Wabash MPI), using textured release paper as release medium on both sides of the cured powder coated substrate. The release paper used on both sides was as ULTRACAST Universal Deco andPR Rustikal (Sappi Fine Paper North America; Boston, Mass.) with a basis weight of 210g/m²And 206g/m². The panel was then cooled under pressure to 70 ° F (21 ℃), the pressure removed, and the release medium removed. The reverse image of the release medium was formed on both sides of the cured powder coated substrate with 100% fidelity.

Example 3

At 400 ℃ F. (204 ℃ C.) T will be used_gA cured powder coated substrate (T) was formed by curing a 11 inch by 0.0016 inch aluminum foil coated with a thermosetting epoxy powder (ASA 61Gray from Dupont) at about 222 ℃ F. (106 ℃ C.) for 10 minutes_gMeasured as in example 1). Once cooled, the foil was pressed against the cured powder coated surface for 15 minutes using a setup similar to fig. 1, at 300 ° F (149 ℃), 900p.s.i. (62bar), in a hot press (Wabash MPI), using textured release paper as the release medium. The release paper is used asPR Ceramic commercially available with a basis weight of 246g/m²(sapphire Paper North America; Boston, MA). The phenolic resin impregnated kraft paper is laminated to the foil by pressing it simultaneously against the uncoated side of the aluminium foil, i.e. between the powder coated substrate 10 and the steel backing plate 13 in figure 1. The pressure and temperature conditions selected for texturing the powder coating are also necessary for cured phenolic resin impregnated kraft paper. The aluminum foil/kraft laminate was then cooled to 70F (21 c) under pressure, the pressure removed, and the release medium removed. The inverse of the release medium is formed in the surface of the powder coating with 100% fidelity. The resulting structure consisted of a cured textured powder coated surface on one side of an aluminum foil and a rigid phenolic sheet laminated to the back side of the aluminum foil.

Example 4

At 400 ℃ F. (204 ℃ C.) T will be used_gAbout 156F (69 deg.C)) The thermosetting polyester powder of (Bike Black; see example 1) the coated 10 inch x 0.02 inch aluminum panels were cured for 12 minutes to form a cured powder coated substrate. Once cooled, the plate was pressed for 20 minutes using an arrangement similar to figure 1 in a 300 ° F (149 ℃), 700p.s.i. (48bar), hot press (Wabash MPI), using an engraved chromium plated plate as the release medium. At this point, the release paper 14 was replaced with an engraved chrome plated plate, with the engraved surface in contact with the surface 16 of the powder coated plate. The panel was then cooled under pressure to 70 ° F (21 ℃), the pressure removed, and the release medium removed. The inverse of the release medium is formed in the surface of the powder coating with 100% fidelity.

Example 5

At 400 ℃ F. (204 ℃ C.) T will be used_gA4 inch by 6 inch by 0.02 inch aluminum panel coated with thermosetting polyester powder (Silvadilofrom Dupont) at about 156F (69℃) was cured for 12 minutes to form a cured powder coated substrate (T)_gMeasured as in example 1). Once cooled, the aluminum panels were pressed for 15 minutes using a setup similar to fig. 1 at 280 ° F (138 ℃), 400p.s.i. (28bar), in a hot press (Wabash MPI), using textured release paper as the release medium. The release paper is used asVEZ Flat (sapphire Paper North America; Boston, Mass.) is commercially available with a basis weight of 154g/m². The panel was then cooled under pressure to 70 ° F (21 ℃), the pressure removed, and the release medium removed. The inverse of the release medium is formed in the surface of the powder coating with 100% fidelity.

The scope of the methods of the following claims is not to be limited by the specific methods described herein, which are intended as illustrations of certain aspects of the claims, and any methods functionally equivalent thereto are intended to be within the scope of this application. In addition to the methods shown and described herein, various modifications of these methods are intended to be included within the scope of the appended claims. Moreover, while certain representative methods and aspects thereof have been described in detail, other methods are intended to be within the scope of the appended claims. Accordingly, the present application expressly refers to a combination of steps, elements, components or integers; however, other combinations of steps, elements, components or structures are included, even if not explicitly mentioned.

Claims (30)

1. A method of imparting a texture to a cured powder coated surface comprising:

providing a substrate having a surface with a cured thermosetting powder coating;

heating the cured powder coating to a temperature above T of the cured powder coating_gThe temperature of (a);

t after heating the cured powder coating above the T of the cured powder coating_gAfter the temperature of (a), imparting a texture to the cured powder coating using a release medium having a repeating surface, and

the release medium is removed from the cured textured powder coating.

2. The method of claim 1, further comprising pressing the release medium against the cured powder coating using a static press.

3. The method of claim 2, wherein the press is heated.

4. The method of claim 1, further comprising pressing the release medium against the cured powder coating using a pressure nip.

5. The method of claim 4 wherein said pressure nip is heated.

6. The method of claim 1, wherein the release medium is a release sheet.

7. The method of claim 1, wherein the release medium is in the form of a web.

8. The method of claim 6, wherein the release medium is paper or film.

9. The method of claim 7, wherein the release medium is paper or film.

10. The method of claim 2, wherein the release medium is pressed against the cured powder coating at a pressure of from 50p.s.i. to 1400p.s.i.

11. The method of claim 4, wherein the release medium is pressed against the cured powder coating at a pressure of from 50p.s.i. to 1400p.s.i.

12. The method of claim 2, wherein the release medium is pressed against the cured powder coating at a pressure of 400p.s.i. to 700p.s.i.

13. The method of claim 4, wherein the release medium is pressed against the cured powder coating at a pressure of 400p.s.i. to 700p.s.i.

14. The method of claim 1, wherein the release medium having a repeating surface is an engraved plate or an engraved roll.

15. The method of claim 1, wherein the release medium has a surface morphology on the repeating surfaces that is lower than the wavelength of light.

16. The method of claim 1, wherein the repetitive surface of the release medium is reproduced within the cured powder coating with a fidelity of up to 100%.

17. The method of claim 1, wherein the coating is at a T greater than the cured powder coating_gThe modulus of the release medium is greater than the modulus of the cured powder coating being textured.

18. The method of claim 1, further comprising providing an isolation medium by: applying a curable release coating to the flexible web, imparting a texture to the curable release coating, and curing the curable release coating to form a textured surface layer.

19. The method of claim 18, wherein the texture is imparted to the curable release coating on the flexible web using a roller engraved with a repeating pattern.

20. The method of claim 1, further comprising relief printing a release medium prior to imparting texture to the cured powder coating.

21. The method of claim 1, wherein the removing is performedCooling the cured powder coating to below the T of the cured powder coating prior to release of the dielectric_g。

22. The method of claim 1, further comprising:

applying a dry free-flowing powder of a curable thermoset material to the substrate to form a powder layer;

heating the powder layer sufficient to cause the powder to melt; and

and curing the powder layer to form a substrate having a cured powder coating on a surface thereof.

23. The method of claim 22, wherein the curable material comprises an initiator that is activatable by exposure to radiation.

24. The method of claim 22, wherein said curable material further comprises a material capable of absorbing said radiation.

25. A method of applying a textured coating to a substrate comprising:

applying a dry free-flowing powder of a curable thermoset material to a substrate to form a powder layer;

heating the powder layer sufficient to cause the powder to melt and form a uniform layer;

curing the uniform layer to form a cured powder coating on the substrate;

heating the cured powder coating to a temperature above T of the cured powder coating_gThe temperature of (a);

imparting a texture to the cured powder coating using a release medium having a repeating surface, and

the release medium is removed from the cured textured powder coating.

26. The method of claim 1, wherein the cured powder coating is a radiation cured powder coating.

27. The method of claim 26, wherein the radiation curable material comprises an initiator capable of being activated by exposure to radiation.

28. The method of claim 26, wherein the radiation-curable material comprises a material capable of absorbing radiation.

29. The method of claim 26, further comprising

Applying a dry free-flowing powder of a radiation curable material to a substrate to form a powder layer;

heating the powder layer sufficiently to cause the powder to melt; and

the powder layer is radiation cured to form a substrate having a cured powder coating on a surface thereof.

30. The method of claim 29, wherein radiation curing the powder layer comprises exposing the powder layer to ultraviolet light.