Fluorocarbon release coating
10967399 · 2021-04-06
Assignee
Inventors
- Ta-Hua Yu (Woodbury, MN, US)
- Moses M. David (Woodbury, MA)
- Kevin D. Hagen (St. Paul, MN, US)
- Samuel J. Carpenter (Shoreview, MN)
- Eric J. Hanson (Hudson, WI, US)
- Martin B. Wolk (Woodbury, MN)
- Steven J. McMan (Stillwater, MN)
- Evan L. Schwartz (Vadnais Heights, MN)
Cpc classification
B32B1/00
PERFORMING OPERATIONS; TRANSPORTING
C08J2367/02
CHEMISTRY; METALLURGY
C08J7/043
CHEMISTRY; METALLURGY
B32B27/304
PERFORMING OPERATIONS; TRANSPORTING
B32B27/308
PERFORMING OPERATIONS; TRANSPORTING
B05D1/62
PERFORMING OPERATIONS; TRANSPORTING
B32B3/30
PERFORMING OPERATIONS; TRANSPORTING
B05D5/083
PERFORMING OPERATIONS; TRANSPORTING
B05D3/0486
PERFORMING OPERATIONS; TRANSPORTING
International classification
B32B27/30
PERFORMING OPERATIONS; TRANSPORTING
B05D7/00
PERFORMING OPERATIONS; TRANSPORTING
B05D1/00
PERFORMING OPERATIONS; TRANSPORTING
B32B1/00
PERFORMING OPERATIONS; TRANSPORTING
B32B3/30
PERFORMING OPERATIONS; TRANSPORTING
B05D5/08
PERFORMING OPERATIONS; TRANSPORTING
Abstract
An organofluorine coating on a major surface of a substrate, wherein the organofluorine coating has a surface composition of about 5 at % to about 15 at % oxygen and about 30 at % to about 50 at % fluorine.
Claims
1. An organofluorine coating on a major surface of a substrate, wherein the organofluorine coating has a surface composition of about 5 at % to 15 at % oxygen and about 30 at % to 50 at % fluorine; wherein the major surface of the substrate comprises protruding or recessed structures with a density of about 10 structures per mm.sup.2 to about 10,000 structures per mm.sup.2, and wherein the coating overlies and conforms to the structures.
2. The coating of claim 1, wherein the coating has a thickness of less than about 500 nm.
3. The coating of claim 1, wherein the coating has a release peel force from the substrate of less than about 15 grams/inch.
4. A method of making the coating of claim 1, comprising: introducing a gaseous fluorocarbon reactant into a reaction chamber; reacting the gaseous fluorocarbon reactant in the presence of a plasma and sufficient oxygen to form an organofluorine coating on a major surface of a substrate, wherein the organofluorine coating has a thickness of less than about 500 nm and wherein the coating comprises about 0.25 at % to about 2.5 at % of oxygen in fluoroether form.
5. An article comprising an organofluorine coating on a major surface of a substrate, wherein the organofluorine coating has a surface composition of about 5 at % to 15 at % oxygen and about 30 at % to 50 at % fluorine; wherein the major surface of the substrate comprises protruding or recessed structures with a density of about 10 structures per mm.sup.2 to about 10,000 structures per mm.sup.2, wherein the coating overlies and conforms to the structures, wherein the substrate comprises a polymeric film, and wherein the organofluorine coating comprises fluoroether species.
6. The article of claim 5, wherein the organofluorine coating has a thickness of less than about 500 nm.
7. The article of claim 5, further comprising: a barrier functional coating on the organofluorine coating, wherein the barrier functional coating comprises a polymeric layer on the organofluorine coating and a metal oxide layer on the polymeric layer.
8. An organofluorine coating on a major surface of a substrate, wherein the organofluorine coating has a surface composition of about 5 at % to 15 at % oxygen and about 30 at % to 50 at % fluorine; wherein the major surface of the substrate comprises protruding or recessed structures with a density of about 10 structures per mm.sup.2 to about 10,000 structures per mm.sup.2, and wherein the coating overlies and conforms to the structures, wherein the organofluorine coating is a fluoropolymer comprising copolymeric repeat units derived from at least one of fluorocarbons having a formula C.sub.xF.sub.y and oxyfluorocarbons having a formula C.sub.xF.sub.yO.sub.z, wherein x, y, and z are non-zero positive integers with x=1-6, y=4-14, and z=1, and wherein the values of x, y and z are selected such that the coating comprises about 5 at % to about 15 at % oxygen and about 30 at % to about 50 at % fluorine.
9. The coating of claim 8, wherein the fluorocarbons and oxyfluorocarbons are chosen from CF.sub.4, C.sub.2F.sub.6, C.sub.3F.sub.8, C.sub.4F.sub.10, and C.sub.6F.sub.14, C.sub.6F.sub.12O, and combinations thereof.
10. The coating of claim 9, wherein the fluorocarbon is C.sub.6F.sub.14.
11. An organofluorine coating on a major surface of a substrate, wherein the organofluorine coating has a surface composition of about 5 at % to 15 at % oxygen and about 30 at % to 50 at % fluorine; wherein the major surface of the substrate comprises protruding or recessed structures with a density of about 10 structures per mm.sup.2 to about 10,000 structures per mm.sup.2, and wherein the coating overlies and conforms to the structures, wherein the organofluorine coating is a fluoropolymer comprising repeat units derived from fluorocarbons having a formula C.sub.xF.sub.y, wherein x=1-6 and y=4-14, reacted with an amount of oxygen sufficient to provide a copolymer with about 5 at % to about 15 at % oxygen and about 30 at % to about 50 at % fluorine.
12. The coating of claim 11, wherein the fluorocarbons are chosen from CF.sub.4, C.sub.2F.sub.6, C.sub.3F.sub.8, C.sub.4F.sub.10, and C.sub.6F.sub.14, and combinations thereof.
Description
BRIEF DESCRIPTION OF DRAWINGS
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(9) Like symbols in the figures indicate like elements.
DETAILED DESCRIPTION
(10) In one aspect, the present disclosure is directed to an organofluorine release coating layer on a substrate, wherein the release coating has a surface composition of about 5 atomic % (at %) to about 15 at % oxygen and about 30 at % to about 50 at % fluorine. In some embodiments, the organofluorine release coating has a surface composition including fluoroether species with about 0.25 at % to about 2.5 at % oxygen in fluoroether form. The organofluorine layer may also be formed as a freestanding thin film.
(11) In some embodiments, the organofluorine release coating is a fluoropolymer including copolymeric repeat units derived from at least one of fluorocarbons having a formula C.sub.xF.sub.y and oxyfluorocarbons having a formula C.sub.xF.sub.yO.sub.z, wherein x, y, and z are non-zero positive integers with x=1-6, y=4-14, and z=1. The values of x, y and z are selected such that the resulting copolymeric coating includes about 5 atomic at % to about 15 at % oxygen and about 30 at % to about 50 at % fluorine. In some embodiments, the fluoropolymer includes repeat units derived from fluorocarbons having a formula C.sub.xF.sub.y, wherein x=1-6 and y=4-14, which are reacted in the presence of sufficient oxygen to provide a copolymer with about 5 at % to about 15 at % oxygen and about 30 at % to about 50 at % fluorine.
(12) While not wishing to be bound by any theory, presently available evidence indicates that the copolymeric organofluorine release coating formed from the reaction of at least one of the fluorocarbon and the oxyfluorocarbons includes periodically randomly occurring perfluoropolyether repeat units within and pendant from the copolymer backbone such that oxygen is present in the coating at about 0.25 at % to about 2.5 at % in fluoroether form.
(13) In some embodiments, which are not intended to be limiting, suitable fluorocarbon reactants C.sub.xF.sub.y used to form the copolymeric organofluorine release coating include CF.sub.4, C.sub.2F.sub.6, C.sub.3F.sub.8, C.sub.4F.sub.10, and C.sub.6F.sub.14, while suitable oxyfluorocarbon reactants include C.sub.6F.sub.12O.
(14) The copolymeric organofluorine release coating can be formed on a wide variety of substrates including, but not limited to, polymeric films, metals, metal oxides, ceramics, glasses, papers, and nonwoven materials. Suitable polymeric films include, for example, polyolefins such as polyethylene or polypropylene, polyvinyl chloride, polycarbonate, polyester, polyether, polyamide, polyimide, polyvinylalcohol, polyurethane, polycellulose. Suitable metals include, for example, copper, iron, stainless steel, aluminum, nickel, and alloys thereof. In various embodiments, the substrate on which the copolymeric organofluorine release coating is formed is a continuous film or sheet, but may be a flat plate, a hollow filament, a cylinder, a rod, sphere, block, powder and the like.
(15) Referring to a process 10 shown schematically in
(16) The release coating layer 12 on the release liner may then have a functional coating 18 applied thereon by any suitable wet or dry coating technique. Various functional layers or coatings 18 can be applied on the coating layer 12 including, but not limited to, polymeric films or layers, metals, visible light-transmissive conductive layers or electrodes (e.g., indium tin oxide (ITO)); antistatic coatings or films; flame retardants; UV stabilizers; abrasion resistant or hardcoat materials; optical coatings; anti-fogging materials; magnetic or magneto-optic coatings or films; photographic emulsions; prismatic films; holographic films or images; adhesives such as pressure sensitive adhesives or hot melt adhesives; primers to promote adhesion to adjacent layers, and the like.
(17) For example, in one embodiment (an example is shown in
(18) In some embodiments, the polymeric coating layer on the release coating layer 12 is an acrylate with a Tg of at least about 110° C., or at least about 150° C., or at least about 200° C. Especially preferred monomers that can be used to form the first layer include urethane acrylates (e.g., CN-968, Tg=about 84° C. and CN-983, Tg=about 90° C., both commercially available from Sartomer Co.), isobornyl acrylate (e.g., SR-506, commercially available from Sartomer Co., Tg=about 88° C.), dipentaerythritol pentaacrylates (e.g., SR-399, commercially available from Sartomer Co., Tg=about 90° C.), epoxy acrylates blended with styrene (e.g., CN-120580, commercially available from Sartomer Co., Tg=about 95° C.), di-trimethylolpropane tetraacrylates (e.g., SR-355, commercially available from Sartomer Co., Tg=about 98° C.), diethylene glycol diacrylates (e.g., SR-230, commercially available from Sartomer Co., Tg=about 100° C.), 1,3-butylene glycol diacrylate (e.g., SR-212, commercially available from Sartomer Co., Tg=about 101° C.), pentaacrylate esters (e.g., SR-9041, commercially available from Sartomer Co., Tg=about 102° C.), pentaerythritol tetraacrylates (e.g., SR-295, commercially available from Sartomer Co., Tg=about 103° C.), pentaerythritol triacrylates (e.g., SR-444, commercially available from Sartomer Co., Tg=about 103° C.), ethoxylated (3) trimethylolpropane triacrylates (e.g., SR-454, commercially available from Sartomer Co., Tg=about 103° C.), ethoxylated (3) trimethylolpropane triacrylates (e.g., SR-454HP, commercially available from Sartomer Co., Tg=about 103° C.), alkoxylated trifunctional acrylate esters (e.g., SR-9008, commercially available from Sartomer Co., Tg=about 103° C.), dipropylene glycol diacrylates (e.g., SR-508, commercially available from Sartomer Co., Tg=about 104° C.), neopentyl glycol diacrylates (e.g., SR-247, commercially available from Sartomer Co., Tg=about 107° C.), ethoxylated (4) bisphenol a dimethacrylates (e.g., CD-450, commercially available from Sartomer Co., Tg=about 108° C.), cyclohexane dimethanol diacrylate esters (e.g., CD-406, commercially available from Sartomer Co., Tg=about 110° C.), isobornyl methacrylate (e.g., SR-423, commercially available from Sartomer Co., Tg=about 110° C.), cyclic diacrylates (e.g., IRR-214, commercially available from UCB Chemicals, Tg=about 208° C.) and tris (2-hydroxy ethyl) isocyanurate triacrylate (e.g., SR-368, commercially available from Sartomer Co., Tg=about 272° C.), acrylates of the foregoing methacrylates and methacrylates of the foregoing acrylates.
(19) A variety of inorganic barrier materials can be employed on the polymeric coating layer. Suitable inorganic barrier materials include metal oxides, metal nitrides, metal carbides, metal oxynitrides, metal oxyborides, and combinations thereof, e.g., silicon oxides such as silica, aluminum oxides such as alumina, titanium oxides such as titania, indium oxides, tin oxides, indium tin oxide (ITO), tantalum oxide, zirconium oxide, niobium oxide, boron carbide, tungsten carbide, silicon carbide, aluminum nitride, silicon nitride, boron nitride, aluminum oxynitride, silicon oxynitride, boron oxynitride, zirconium oxyboride, titanium oxyboride, and combinations thereof. Indium tin oxide, silicon oxide, aluminum oxide and combinations thereof are especially preferred inorganic barrier materials. ITO is an example of a special class of ceramic materials that can become electrically conducting with the proper selection of the relative proportions of each elemental constituent. The inorganic barrier layers preferably are formed using techniques employed in the film metallizing art such as sputtering (e.g., cathode or planar magnetron sputtering), evaporation (e.g., resistive or electron beam evaporation), chemical vapor deposition, plating and the like. Most preferably the inorganic barrier layers are formed using sputtering, e.g., reactive sputtering Enhanced barrier properties have been observed when the inorganic layer is formed by a high energy deposition technique such as sputtering compared to lower energy techniques such as conventional chemical vapor deposition processes.
(20) In another embodiment, (an example is shown in
(21) The functional coating or layer 18 may subsequently be peeled away from the release coating layer 12 and transferred. In the embodiment of
(22) In the embodiment illustrated in
(23) In another embodiment of a process 20 illustrated schematically in
(24) The protruding microstructures 25 on the structured substrate 24 have a topographical feature density of greater than 10, or greater than 100, or greater than 1000, or greater than 10,000 features or greater per square millimeter (mm.sup.2) on the substrate. Non-limiting examples of microstructures or nanostructures 25 that can be conformally covered by the copolymeric organofluorine release coating layer 22 include hemispheres, right pyramids, trigonal pyramids, square pyramids, quadrangle pyramids, “V” grooves, and the like.
(25) The release coating layer 22 on the structured release liner 26 may then have a structured functional coating 28 applied thereon by any suitable wet or dry coating technique. The structured functional coating 28 may subsequently be peeled away from the structured release coating layer 22 and transferred with structures 25 intact, leaving behind the copolymeric organofluorine release coating layer 22 on the release liner 26.
(26) The copolymeric organofluorine release coating may be applied on the substrate by a wide variety of techniques, but in one example embodiment, which is not intended to be limiting, a plasma deposition technique has been found to efficiently and reproducibly form the release coating on a substrate in a single step in roll-to-roll fashion at low cost. Referring to an embodiment of a process 100 shown in
(27) The interior of the chamber 102 may be at atmospheric pressure or be maintained under vacuum, and in some embodiments the interior of the chamber 102 may be filled with an inert gas such as nitrogen, argon or the like.
(28) A first fluorocarbon or oxyfluorocarbon gaseous reactant stream 116 including at least one of fluorocarbons having a formula C.sub.xF.sub.y and oxyfluorocarbons having a formula C.sub.xF.sub.yO.sub.z, wherein x, y, and z are non-zero positive integers with x=1-6, y=4-14, and z=1 is introduced into the chamber 102. The fluorocarbon or oxyfluorocarbon gaseous reactant stream 116 can include one or a mixture of gases, and suitable gases include, but are not limited to, CF.sub.4, C.sub.2F.sub.6, C.sub.3F.sub.8, C.sub.4F.sub.10, and C.sub.6F.sub.14, C.sub.6F.sub.12O, and combinations thereof. An optional second reactive or non-reactive gaseous stream 118 may also be introduced into the chamber 102, and the second gaseous stream includes a non-fluorinated compound such as hydrogen, helium, oxygen, fluorine, argon, carbon monoxide, carbon dioxide, nitrogen dioxide, steam, and combinations thereof. In some embodiments, the second gaseous stream 118 is oxygen or a gas containing oxygen.
(29) The rotatable drum-like cylindrical electrode 104 is energized and set in motion such that a portion 120 of the film web 110 moves around the exterior 114 of the electrode and a plasma 122 is generated within the chamber 102. As the film 110 moves over the surface 114, the portion 120 of the film 110 is exposed to the plasma 122, which causes the reactants in the first gaseous stream 116 and the optional second gaseous stream 118 to react on the exposed surface 123 of the film web 110 to form a copolymeric organofluorine release coating layer thereon. A portion 124 of the film web 110 including the release coating layer 132 thereon traverses a second set of rollers 130 and then may be removed from the chamber 102 for further processing.
(30) The flow rates of the first gaseous stream 116 and the optional second gaseous stream 118 are selected to produce a release coating layer 132 with a desired combination of release characteristics for a selected application. In some embodiments, which are not intended to be limiting, the release coating layer 132 includes about 5 atomic at % to about 15 at % oxygen and about 30 at % to about 50 at % fluorine. In some embodiments, the flow rates of the first gaseous stream 116 and the optional second gaseous stream 118 are selected to produce a release coating layer 132 including oxygen at about 0.25 at % to about 2.5 at % in fluoroether form. For example, in some non-limiting embodiments the first gaseous stream 116 includes a fluorocarbon C.sub.xF.sub.y and the second gaseous stream 118 includes oxygen, and the reactant gases are introduced into the chamber 102 at a C.sub.xF.sub.y:O ratio of from about 4:1 to about 1:1, about 3:2 to about 2:3, at about 4 parts C.sub.xF.sub.y to about 1 part oxygen, or at about 3 parts C.sub.xF.sub.y to about 2 parts oxygen, to provide a release coating layer 132 with excellent release properties.
(31) Embodiment of the invention will now be described with reference to the following non-limiting examples.
EXAMPLES
(32) These Examples are merely for illustrative purposes and are not meant to be overly limiting on the scope of the appended claims. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the present disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
(33) Summary of Materials
(34) Unless otherwise noted, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight. Solvents and other reagents used may be obtained from Sigma-Aldrich Chemical Company (Milwaukee, Wis.) unless otherwise noted. In addition, Table 1 provides abbreviations and a source for all materials used in the Examples below:
(35) TABLE-US-00001 TABLE 1 Materials. Abbreviation or Tradename Description Source C.sub.6F.sub.14 Perfluorohexane 3M Corporation (St. Paul, MN) SR833S Tricyclodecane Sartomer Americas (Exton, PA) dimethanol diacrylate PET 1.97 3M PTA-Clear 3M Corporation (St. Paul, MN) film Indium Tin 95% In/5% Sn ceramic Umicore Thin Film Products Oxide target target (Providence, RI) 3M item #8403 green silicone tape 3M Corporation (St. Paul, MN) Scotch tape 3M Corporation (St. Paul, MN)
Methods
(36) Plasma Coater Method
(37) Plasma fluorochemical thin film coatings were deposited using the plasma treatment system described in U.S. Pat. No. 5,888,594 (David et al.) with some modifications. The width of the drum electrode was increased to 42.5 inches (108 cm) and the separation between the two compartments within the plasma system was removed so that all the pumping was carried out by means of turbo-molecular pumps.
(38) Rolls of polymeric film were mounted within the chamber, the film wrapped around the drum electrode and secured to the take up roll on the opposite side of the drum. The unwind and take-up tensions were maintained at 6 pounds, and 12 pounds, respectively. The chamber door was closed and the chamber pumped down to a base pressure of 5×10.sup.−4 torr. A gas mixture of either pure C.sub.6F.sub.14, or oxygen combined with C.sub.6F.sub.14 was introduced into the chamber under various conditions described in the examples below. Plasma was turned on at a power of 3000 watts by applying radio frequency power to the drum and the drum rotation initiated so that the film was transported at a speed of 10 feet per minute (ft/min) normally, or at different line speeds as indicated in specific examples below. In certain cases, sheets of substrate film were taped onto the cylindrical electrode, and treated for a specified amount of time as indicated in the examples below.
(39) Roll to Roll Vacuum Coating Method
(40) The roll-to-roll vacuum coater is illustrated schematically in
(41) Batch Deposition Coater
(42) Aluminum was coated onto 152 mm by 152 mm substrates by magnetron physical vapor deposition. The films were sputtered from a 76.2 mm round aluminum target in a batch coater. The substrate was placed on a substrate holder set up inside a vacuum chamber with a sputtering metal target located at a height of 228.6 mm above the substrate holder. After the chamber was evacuated to 6×10.sup.−6 torr base pressure, sputter gas of argon was admitted inside the chamber and total pressure of the chamber was adjusted to 5 millitorr. Sputtering was initiated using a DC power supply at a constant power level of 0.5 kilowatts.
(43) Peel Test
(44) Peel test was performed following the test method of ASTM D 3330/D 3330M-04 using an IMASS Peel Tester SP-101A (IMASS, Hingham, Mass., USA). A strip of 2 inch wide sample was attached to the testing machine with a double-sided tape with the coated side facing up. A strip of 1 inch #8403 tape was then laminated to the sample using a roller. A clamping rod was attached to one end of the #8403 tape and the peel test was conducted at a speed of 90 inch/min. The peel force is reported as an average of multiple samples.
(45) Release Test
(46) A strip of 2 inch wide coated sample was attached to a table with a double-sided tape with the coating side facing up. A strip of Scotch tape was then laminated to the upper surface of the sample using a roller. The Scotch tape was then peeled off from the sample. The surface of the sample and the tape were then visually inspected to determine the releasing properties.
(47) Release Coating Compositions Analysis
(48) Samples were coated with fluorocarbon plasma coating with different levels of O.sub.2 flow rate using the roll-to-roll plasma coating apparatus shown schematically in
Examples 1-5
(49) Referring the schematic diagram in
(50) The plasma coater was operated at a line speed of 10 feet per minute (fpm) with a power of 3000 W, resulting in the formation of a perfluoroalkyl ether release coating 206. Gas flow rates of perfluorohexane (C.sub.6F.sub.14) and oxygen (O.sub.2) in the plasma coater are provided in Table 2 for each example and are given as standard cubic centimeters per minute (sccm).
(51) Referring again to
(52) Referring again to
(53) Results of peel testing are shown in chart form in
(54) TABLE-US-00002 TABLE 2 Gas flow rates used to fabricate perfluoroalkyl ether release coatings and peel force values for multilayer constructions comprising them. Peel force (grams per Example Gas flow rates inch) Example 1 500 sccm C.sub.6F.sub.14 10.45 Example 2 400 sccm C.sub.6F.sub.14 + 100 sccm O.sub.2 7.8 Example 3 300 sccm C.sub.6F.sub.14 + 200 sccm O.sub.2 13.57 Example 4 200 sccm C.sub.6F.sub.14 + 300 sccm O.sub.2 18.7 Example 5 250 sccm C.sub.6F.sub.14 + 250 sccm O.sub.2 19.27
Examples 6-8 & Comparative Examples 1-3
(55) According to the process shown schematically in
(56) As shown in
(57) Referring again to
(58) TABLE-US-00003 TABLE 3 Release coating deposition conditions, aluminum metallization conditions, and release results. Perfluorohexane Oxygen Aluminum Example (sccm) (sccm) metallization Release test Comparative 500 0 0.25 kW Partial release Example 1 3 minutes and slightly 50 seconds difficult to release Comparative 400 100 Partial release Example 2 Example 6 300 200 Release Example 7 200 300 Easy release Comparative 100 400 Not releasable Example 3 Example 8 150 150 Easy release
(59) Various embodiments have been described. These and other embodiments are within the scope of the following claims.