Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C24/00—Coating starting from inorganic powder
  • C23C24/02—Coating starting from inorganic powder by application of pressure only
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C24/00—Coating starting from inorganic powder
  • C23C24/02—Coating starting from inorganic powder by application of pressure only
  • C23C24/04—Impact or kinetic deposition of particles

Definitions

• the present disclosure broadly relates to methods for improving the durability of particle coatings on thermally-softenable films, and articles preparable thereby.
• Coatings of certain particles (e.g., graphite) on substrates can be formed by rubbing a powder containing the particles against a substrate such as, for example, a thermoplastic film.
• a powder coating will be referred to herein as "powder-rubbed coatings".
• powder-rubbed coatings examples include those disclosed in U. S. Pat. No. 6,511,701 Bl (Divigalpitiya et al.).
• powder-rubbed coatings and methods of forming them include those disclosed in U. S. Pat. No. 6,511,701 Bl (Divigalpitiya et al.).
• such films are typically prone to damage by methods such as abrasion and/or rinsing with solvent.
• the present disclosure provides a method comprising exposing a particle coating disposed on a thermally-softenable film to a modulated source of electromagnetic radiation (e.g., a flashlamp), wherein the particle coating comprises loosely bound distinct particles that are not covalently bonded to each other, and are not retained in a binder material other than the thermally-softenable film.
• a modulated source of electromagnetic radiation e.g., a flashlamp
• the present disclosure provides an article made according to the method of the first aspect of the present disclosure.
• the present disclosure provides an article comprising a thermally-softenable film having a particle coating disposed thereon, wherein the particle coating comprises distinct particles that are not covalently bonded to each other, and are not retained in a binder material other than the thermally- softenable film, and wherein at least one portion of the particle coating corresponding to a predetermined pattern has a greater transmittance to visible light than at least one portion of the particle coating that is not disposed within the predetermined pattern.
• the present disclosure provides an article comprising a thermally-softenable film having a particle coating disposed thereon, wherein the particle coating comprises distinct particles that are not chemically bonded to each other and are not retained in a binder material other than the thermally-softenable film, and wherein the change in transmittance is at most 60 percent after abrading the particle coating according to ASTM D6279-15 "Standard Test Method for Rub Abrasion Mar
• visible light refers to electromagnetic radiation having a wavelength of 400 to 700 nanometers (nm).
• powder refers to a free-flowing collection of minute particles.
• pulsed electromagnetic radiation refers to electromagnetic radiation that is modulated to become a series of discrete spikes with increased intensity.
• the spikes may be relative to a background level of electromagnetic radiation that is negligible or zero, or the background level may be at a higher level that is substantially ineffective to increase adhesion of particles in the particle coating to the film.
• thermo-softenable means softenable upon heating.
• particle coating refers to a coating of minute particles which may or may not be free- flowing.
• Fig. 1 is an enlarged schematic side view of an exemplary article 100 according to the present disclosure.
• Fig. 2 is a digital photograph of a mask used in Example 9 (EX-9).
• Fig. 3 is a digital photograph of the flashlamp treated graphite-coated film in EX-9.
• Fig. 4 is a digital photograph of the flashlamp treated graphite-coated film in EX-9
• the present disclosure provides an easy method to enhance the durability of particle coatings (e.g., to solvent abrading) on thermally-softenable films using instantaneous heating by exposure to a modulated source of electromagnetic radiation.
• exemplary article 100 comprises a thermally-softenable (e.g., thermoplastic) film 110 having a particle coating 120 disposed thereon.
• the particle coating comprises distinct particles that are not covalently bonded to each other and are not retained in a binder material other than the thermally-softenable film.
• Particle coatings on thermally-softenable films can be prepared by various known methods including, for example, exposure to an aerosolized powder cloud, contact with a powder bed, coating with a solvent-based powder dispersion coating followed by evaporation of solvent, and/or triboadhesion
• Useful powders comprise minute loosely bound particles capable of absorbing at least one wavelength of the pulsed electromagnetic radiation, preferably corresponding to a majority of the energy of the pulsed electromagnetic radiation.
• Suitable powders are preferably at least substantially unaffected by electromagnetic radiation, but are moderate to strong absorbers of it. This is desirable to maximize the light (electromagnetic radiation) to heat conversion yield without altering the chemical nature of the powder particles.
• Suitable powders include powders comprising graphite, clays, hexagonal boron nitride, pigments, inorganic oxides (e.g., alumina, calcia, silica, ceria, zinc oxide, or titania), metal(s), organic polymeric particles (e.g., polytetrafluoroethylene, polyvinylidene difluoride), carbides (e.g., silicon carbide), flame retardants (e.g., aluminum trihydrate, aluminum hydroxide, magnesium hydroxide, sodium
• the powder particles have an average particle size of 0.1 to 100 micrometers, more preferably 1 to 50 micrometers, and more preferably 1 to 25 micrometers, although this is not a requirement.
• Graphite and hexagonal boron nitride are particularly preferred in many applications.
• the particle coating after application, may consist essentially of (i.e., be at least 98 percent by weight, preferably at least 99 percent by weight), or even consist of the powder particles (e.g., graphite particles).
• the particle coating Prior to exposure to the electromagnetic radiation the particle coating comprises loosely bound distinct particles that are not covalently bonded to each other, and are not retained in a binder material other than the thermally-softenable film itself.
• the thermally-softenable film may comprise one or more thermally-softenable (e.g., lightly crosslinked and/or thermoplastic) polymers.
• thermally-softenable polymers that may be suitable for inclusion in a thermally-softenable film include polycarbonates, polyesters, polyamides, polyimides, polyurethanes, polyetherketone (PEK), polyetheretherketone (PEEK), polyphenylene sulfide, polyacrylics (e.g., polymethyl methacrylate), polyolefins (e.g., polyethylene, polypropylene, biaxially- oriented polypropylene), and combinations of such resins.
• the pulsed electromagnetic radiation may come from any source(s) capable of generating sufficient fluence and pulse duration to effect sufficient heating of the thermally-softenable film to cause the particle coating to bind more tightly to it.
• At least three types of sources may be effective for this purpose: flashlamps, lasers, and shuttered lamps.
• flashlamps lasers
• shuttered lamps The selection of appropriate sources will typically be influenced by desired process conditions such as, for example, line speed, line width, spectral output, and cost.
• the pulsed electromagnetic radiation is generated using a flashlamp.
• a flashlamp xenon and krypton flashlamps are the most common. Both provide a broad continuous output over the wavelength range 200 to 1000 nanometers, however the krypton flashlamps have higher relative output intensity in the 750-900 nm wavelength range as compared to xenon flashlamps which have more relative output in the 300 to 750 nm wavelength range.
• xenon flashlamps are preferred for most applications, and especially those involving graphite powder.
• Many suitable xenon and krypton flashlamps are commercially available from vendors such as Excelitas Technologies Corp. of Waltham, Massachusetts and Heraeus of Hanau, Germany.
• the pulsed electromagnetic radiation can be generated using a pulsed laser.
• Suitable lasers may include, for example, excimer lasers (e.g., XeF (351 nm), XeCl (308 nm), and KrF (248 nm)), solid state lasers (e.g., ruby 694 nm)), and nitrogen lasers (337.1 nm).
• the pulsed electromagnetic radiation is generated using a continuous light source and a shutter (preferably a rotating aperture/shutter to reduce overheating of the shutter).
• Suitable light sources may include high-pressure mercury lamps, xenon lamps, and metal-halide lamps.
• the electromagnetic radiation spectrum is preferably most intense at wavelength(s) that are strongly absorbed by the powder particles, although this is not a requirement.
• the electromagnetic radiation spectrum is preferably most intense in spectral regions in which the powder is least reflective, although this is not a requirement.
• the source of pulsed electromagnetic radiation is capable of generating a high fluence (energy density) with high intensity (high power per unit area), although this is not a requirement.
• high fluence energy density
• intensity high power per unit area
• the pulse duration is preferably short; e.g., less than 10 milliseconds, less than 1 millisecond, less than 100 microseconds, less than 10 microseconds, or even less than 1 microsecond, although this is not a requirement.
• the pulsed electromagnetic radiation preferably be powerful, but the exposure area is preferably large and the pulse repetition rate is preferably fast (e.g., 100 to 500 Hz).
• the modulated electromagnetic radiation may be directed through a mask having transmissive and non-transmissive regions according to a predetermined pattern (e.g., see Fig 2.).
• exposed regions of the particle coating may become more transparent to visible light than unexposed region of the particle coating (see Fig. 3).
• an optional development step e.g., mild abrasion with a solvent-soaked wiper
• a particle coating remains in the exposed region according to the predetermined pattern while it is substantially or completely removed in the unexposed (i.e., blocked) region (see FIG. 4).
• the present disclosure provides a method comprising exposing a particle coating disposed on a thermally-softenable film to a modulated source of electromagnetic radiation, wherein the particle coating comprises loosely bound distinct particles that are not covalently bonded to each other, and are not retained in a binder material other than the thermally-softenable film.
• the present disclosure provides a method according to the first embodiment, wherein the particle coating comprises at least one of graphite or hexagonal boron nitride.
• the present disclosure provides a method according to the first or second embodiment, wherein the particle coating consists essentially of graphite.
• the present disclosure provides a method according to any one of the first to third embodiments, wherein the modulated source of electromagnetic radiation comprises a flashlamp.
• the present disclosure provides a method according to any one of the first to third embodiments, wherein the modulated source of electromagnetic radiation comprises a pulsed laser.
• the present disclosure provides a method according to any one of the first to third embodiments, wherein the particle coating comprises a powder-rubbed coating.
• the present disclosure provides a method according to any one of the first to sixth embodiments, wherein the particle coating is exposed to the pulsed electromagnetic radiation according to a predetermined pattern.
• the present disclosure provides an article made according to the method of any one of the first to seventh embodiments.
• the present disclosure provides an article comprising a thermally- softenable film having a particle coating disposed thereon, wherein the particle coating comprises distinct particles that are not covalently bonded to each other, and are not retained in a binder material other than the thermally-softenable film, and wherein at least one portion of the particle coating corresponding to a predetermined pattern has a greater transmittance to visible light than at least one portion of the particle coating that is not disposed within the predetermined pattern.
• the present disclosure provides an article according to the ninth embodiment, wherein the particle coating comprises at least one of graphite or hexagonal boron nitride.
• the present disclosure provides an article according to the ninth or tenth embodiment, wherein the particle coating consists essentially of graphite.
• the present disclosure provides an article according to any one of the ninth to eleventh embodiments, wherein the thermally-softenable film comprises polyethylene terephthalate.
• the present disclosure provides an article according to any one of the ninth to eleventh embodiments, wherein the thermally-softenable film comprises polyethylene terephthalate.
• the present disclosure provides an article according to any one of the ninth to twelfth embodiments, wherein the predetermined pattern comprises a circuit trace.
• the present disclosure provides an article according to any one of the ninth to thirteenth embodiments, wherein the at least one portion of the particle coating that is not disposed within the predetermined pattern comprises a powder-rubbed coating.
• the present disclosure provides an article comprising a thermally- softenable film having a particle coating disposed thereon, wherein the particle coating comprises distinct particles that are not chemically bonded to each other and are not retained in a binder material other than the thermally-softenable film, and wherein the change in transmittance is at most 60 percent after abrading the particle coating according to ASTM D6279-15 "Standard Test Method for Rub Abrasion Mar Resistance of High Gloss Coatings" with the 25 mm friction element being outfitted with a two inch square Crockmeter cloth soaked in isopropanol for three seconds.
• the present disclosure provides an article according to the fifteenth embodiment, wherein the particle coating comprises a powder-rubbed coating.
• the present disclosure provides an article according to the fifteenth or sixteenth embodiment, wherein at least one portion of the particle coating corresponding to a predetermined pattern has a greater transmittance to visible light than at least one portion of the particle coating that is not disposed within the predetermined pattern.
• graphite coatings were applied onto PET films by placing a small amount of MICRO850 on the PET films. The graphite was then rubbed against the film using a WEN lOPMC 10-inch (25.8-cm) random orbital waxer/polisher (WEN Products, Elgin, Illinois) equipped with a wool polishing bonnet. The relative amount of graphite coating deposited on the PET film was determined by measuring the surface resistivity using a four-point probe and/or light transmittance.
• CEX-C and EX10 to EX12 were evaluated for durability according to ASTM D6279-15 "Standard Test Method for Rub Abrasion Mar Resistance of High Gloss Coatings", ASTM International, West Conshocken, Pennsylvania, with the 25 mm friction element being outfitted with a two inch (5.1 cm) square Crockmeter cloth soaked in isopropanol for three seconds.
• Crockmeter cloth is available from Testfabrics, Inc. West Pittson, Pennsylvania.
• Crockmeter cloth conforms to the specifications of ASTM D3690-02(2009) "Standard Performance Specification for Vinyl-Coated and Urethane-Coated Upholstery Fabrics— Indoor”. Transmittance of graphite -coated film specimens was measured before and after durability testing. All transmittance measurements represent an average of at least 3 measurements.
• T fflm is the transmittance of the underlying polymer film
• Tc is the transmittance of that same film after the coating and treatments had been applied
• T abraded is the transmittance of the coating after being subjected to the desired number of abrading cycles.
• Transmittance values of the films are typically around 92 ⁇ 5%, depending on the quality of the substrate used. Smaller changes in
• EXAMPLES EX-1 to EX- 12 and COMPARATIVE EXAMPLES CEX-A to CEX-C CEX-A to CEX-C and EX-1 to EX-12 were prepared by subjecting graphite coated PET substrate films prepared as described above to an Intense Pulsed Light (IPL) irradiation.
• IPL Intense Pulsed Light
• the source used was a SINTERON S-2100 Xe flashlamp equipped with Type C bulb from Xenon
• the substrate was Bare PET.
• EX-1 was placed under the flashlamp with the graphite-coated surface facing up and treated ten times at a pulse rate of 1 Hz and an energy density of 0.4 J/cm 2 .
• CEX-B was prepared in the same manner as CEX-A, except that the substrate was Melinex PET.
• EX-2 was prepared in the same manner as EX-1, except that the substrate was Melinex PET and treated 5 times at a pulse rate of 1 Hz and an energy density of 0.3 J/cm 2 .
• EX-3 and EX-4 were prepared in the same manner as EX-2, except that the film was treated 1 time at a pulse rate of 1 Hz and an energy density of 0.5 J/cm 2 (EX-3) and 1.0 J/cm 2 (EX-4).
• EX-5 was prepared similarly to EX-4, except the film was flipped over such that the graphite coated surface was facing away from the flashlamp bulb.
• EX-6 to EX-8 were prepared by coating three separate sheets of Bare PET with differing amounts of graphite to achieve differing surface resistivity values for each Example. EX-6 to EX-8 were placed under the flashlamp with the graphite-coated surface facing up and treated ten times at a pulse rate of 1 Hz and an energy density of 0.4 J/cm 2 . Table 2, below, reports the change in transmittance ⁇ in %.
• the substrate coated with graphite was Bare PET.
• a chromium/glass patterned photomask shown in Fig. 2 was situated between the flashlamp and the graphite.
• the area directly adjacent to the mask is denoted as the unmasked area, whereas the area beneath the mask was shielded from IPL and is denoted as the masked area.
• the photomask included linear shape openings in the chrome layer having width of approximately about 250 micrometers or having width of approximately about 500 micrometers. This demonstrates the ability of these coatings to be patterned, with the openings portion of the mask representing a desired pattern for improved particle retention.
• Table 3 report the effects of IPL on particle retention of masked and unmasked (patterned) graphite coated PET.
• Fig. 3 shows the resulting pattern, with the portion beneath the openings and masked portion.
• Fig. 4 shows the resulting pattern after being subjected to abrasion as described above, with the portion beneath the openings remaining coated with carbon and the masked portion being devoid of carbon due to abrasion.
• CEX-C CEX-C to EX- 10
• the substrate was Bare PET.
• EX- 10 was placed under the flashlamp with the graphite-coated surface facing up and treated ten times at a pulse rate of 1 Hz and an energy density of 0.4 J/cm 2 .
• EX-11 was prepared in the same manner as EX- 10, except that the film was coated with a different amount of graphite to achieve a higher surface resistivity value than EX- 10.
• EX- 12 was prepared in the same manner EX- 10, except that the substrate was Melinex PET and treated 5 times at a pulse rate of 1 Hz and an energy density of 0.3 J/cm 2 .
• the coated PET specimens were taped on to a moving PET web and conveyed through the e-beam processor at a voltage of 110 keV.
• the web speed and e-beam current applied to the cathode were varied to ensure delivery of the targeted dose.
• Tables 5-7 summarize the effect of heat gun (Table 5), e-beam (Table 6), and biaxial stretch (Table 7) exposures had on particle retention ( ⁇ , %, average normalized change in transmission).
• heat gun an output greater than 232°C and/or for longer than 10 minutes was also applied, but was found to result in both excessive thermal degradation of the polymer or unrealistic processing conditions for manufacturing.
• biaxial stretching stretching larger than 5% was also applied, but was found to result in excessive tension of the polymer leading to film fracture.

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• 2018
  • 2018-06-27 US US16/626,238 patent/US20200115804A1/en not_active Abandoned
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