U.S. patent application number 16/626238 was filed with the patent office on 2020-04-16 for article and method of making the same.
The applicant listed for this patent is 3M INNOVATIVE PROPERTIES COMPANY. Invention is credited to Benjamin R. Coonce, Megan A. Creighton, Joel A. Getschel, Taylor J. Kobe, Morgan A. Priolo, Eric A. Vandre, Onur Sinan Yordem.
Application Number | 20200115804 16/626238 |
Document ID | / |
Family ID | 63207795 |
Filed Date | 2020-04-16 |
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United States Patent
Application |
20200115804 |
Kind Code |
A1 |
Creighton; Megan A. ; et
al. |
April 16, 2020 |
ARTICLE AND METHOD OF MAKING THE SAME
Abstract
A method comprises exposing a particle coating disposed on a
thermally-softenable film to a modulated source of electromagnetic
radiation. 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. Articles
made by the method are also disclosed.
Inventors: |
Creighton; Megan A.;
(Somerville, MA) ; Priolo; Morgan A.; (Woodbury,
MN) ; Getschel; Joel A.; (Osceola, WI) ; Kobe;
Taylor J.; (Woodbury, MN) ; Yordem; Onur Sinan;
(St. Paul, MN) ; Coonce; Benjamin R.; (St. Paul,
MN) ; Vandre; Eric A.; (Roseville, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
3M INNOVATIVE PROPERTIES COMPANY |
St Paul |
MN |
US |
|
|
Family ID: |
63207795 |
Appl. No.: |
16/626238 |
Filed: |
June 27, 2018 |
PCT Filed: |
June 27, 2018 |
PCT NO: |
PCT/IB2018/054772 |
371 Date: |
December 23, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62526720 |
Jun 29, 2017 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 24/02 20130101;
C23C 24/04 20130101 |
International
Class: |
C23C 24/04 20060101
C23C024/04 |
Claims
1-17. (canceled)
18. A method of making an article, the method comprising exposing a
particle coating disposed on a thermally-softenable film to a
modulated source of electromagnetic radiation, wherein the
modulated source of electromagnetic radiation comprises a
flashlamp, wherein the particle coating faces away from the
modulated source of electromagnetic radiation, and 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.
19. The method of claim 18, wherein the particle coating comprises
at least one of graphite or hexagonal boron nitride.
20. The method of claim 18, wherein the particle coating consists
essentially of graphite.
21. The method of claim 18, wherein the particle coating comprises
a powder-rubbed coating.
22. The method of claim 18, wherein the particle coating is exposed
to the pulsed electromagnetic radiation according to a
predetermined pattern.
23. 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.
24. The article of claim 23, wherein the particle coating comprises
a powder-rubbed coating.
25. The article of claim 23, 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.
Description
TECHNICAL FIELD
[0001] The present disclosure broadly relates to methods for
improving the durability of particle coatings on
thermally-softenable films, and articles preparable thereby.
BACKGROUND
[0002] 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. Such powder
coatings will be referred to herein as "powder-rubbed coatings".
Examples of powder-rubbed coatings and methods of forming them
include those disclosed in U.S. Pat. No. 6,511,701 B1
(Divigalpitiya et al.). However, such films are typically prone to
damage by methods such as abrasion and/or rinsing with solvent.
SUMMARY
[0003] In a first aspect, 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.
[0004] By this technique, durability of the powder coating is
improved, while alternative heating methods were prone to damaging
(e.g., warping) the thermally-softenable film.
[0005] Accordingly, in a second aspect, the present disclosure
provides an article made according to the method of the first
aspect of the present disclosure.
[0006] In a third aspect, 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.
[0007] In a fourth aspect, 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.
[0008] As used herein:
[0009] The term "visible light" refers to electromagnetic radiation
having a wavelength of 400 to 700 nanometers (nm).
[0010] The term "powder" refers to a free-flowing collection of
minute particles.
[0011] The term "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.
[0012] The term "thermally-softenable" means softenable upon
heating.
[0013] The term "particle coating" refers to a coating of minute
particles which may or may not be free-flowing.
[0014] Features and advantages of the present disclosure will be
further understood upon consideration of the detailed description
as well as the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is an enlarged schematic side view of an exemplary
article 100 according to the present disclosure.
[0016] FIG. 2 is a digital photograph of a mask used in Example 9
(EX-9).
[0017] FIG. 3 is a digital photograph of the flashlamp treated
graphite-coated film in EX-9.
[0018] FIG. 4 is a digital photograph of the flashlamp treated
graphite-coated film in EX-9 after abrading with a solvent soaked
wiper.
[0019] It should be understood that numerous other modifications
and embodiments can be devised by those skilled in the art, which
fall within the scope and spirit of the principles of the
disclosure.
DETAILED DESCRIPTION
[0020] Advantageously, 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.
[0021] Referring now to FIG. 1, 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.
[0022] 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 (rubbing dry particles
against a substrate to form a powder-rubbed coating) of the powder
using a rubbing process. Examples of triboadhesion methods can be
found in U.S. Pat. No. 6,511,701 B1 (Divigalpitiya et al.), Pat.
No. 6,025,014 (Stango), and Pat. No. 4,741,918 (Nagybaczon et al.).
The remaining methods will be familiar to those of ordinary skill
in the art.
[0023] 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.
[0024] 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 hexametaphosphate, organic phosphonates and
phosphates and ester thereof), carbonates (e.g., calcium carbonate,
magnesium carbonate, sodium carbonate), dry biological powders
(e.g., spores, bacteria), and combinations thereof. Preferably, 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.
[0025] In some embodiments, 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).
[0026] 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.
[0027] The thermally-softenable film may comprise one or more
thermally-softenable (e.g., lightly crosslinked and/or
thermoplastic) polymers. Exemplary 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.
[0028] 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. 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.
[0029] Preferably, the pulsed electromagnetic radiation is
generated using a flashlamp. Of these, 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. In general,
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, Mass. and Heraeus of
Hanau, Germany.
[0030] In another embodiment, 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).
[0031] In yet another embodiment, 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.
[0032] For maximum efficiency, 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. Likewise, in the case of reflective powders, the
electromagnetic radiation spectrum is preferably most intense in
spectral regions in which the powder is least reflective, although
this is not a requirement.
[0033] Preferably, 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. These conditions assure that the sufficient heat is
absorbed to effect increased adhesion of the powder particles to
the film. However, the combination of intensity and fluence should
not be so great/high as to cause ablation, excessive degradation,
or volatilization of the thermally-softenable film. Selection of
appropriate conditions is within the capability of one of ordinary
skill in the art.
[0034] To minimize heating of interior portions of the
thermally-softenable film that cannot interact with the powder
particles, 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.
[0035] To achieve high line speed in continuous manufacturing
processes, not only should 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).
[0036] Advantageously, 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.).
Accordingly, exposed regions of the particle coating may become
more transparent to visible light than unexposed region of the
particle coating (see FIG. 3). After, 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).
Select Embodiments of the Present Disclosure
[0037] In a first embodiment, 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.
[0038] In a second embodiment, 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.
[0039] In a third embodiment, the present disclosure provides a
method according to the first or second embodiment, wherein the
particle coating consists essentially of graphite.
[0040] In a fourth embodiment, 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.
[0041] In a fifth embodiment, 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.
[0042] In a sixth embodiment, 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.
[0043] In a seventh embodiment, 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.
[0044] In an eighth embodiment, the present disclosure provides an
article made according to the method of any one of the first to
seventh embodiments.
[0045] In a ninth embodiment, 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.
[0046] In a tenth embodiment, 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.
[0047] In an eleventh embodiment, the present disclosure provides
an article according to the ninth or tenth embodiment, wherein the
particle coating consists essentially of graphite.
[0048] In a twelfth embodiment, the present disclosure provides an
article according to any one of the ninth to eleventh embodiments,
wherein the thermally-softenable film comprises polyethylene
terephthalate.
[0049] In a twelfth embodiment, the present disclosure provides an
article according to any one of the ninth to eleventh embodiments,
wherein the thermally-softenable film comprises polyethylene
terephthalate.
[0050] In a thirteenth embodiment, the present disclosure provides
an article according to any one of the ninth to twelfth
embodiments, wherein the predetermined pattern comprises a circuit
trace.
[0051] In a fourteenth embodiment, 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.
[0052] In a fifteenth embodiment, 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.
[0053] In a sixteenth embodiment, the present disclosure provides
an article according to the fifteenth embodiment, wherein the
particle coating comprises a powder-rubbed coating.
[0054] In a seventeenth embodiment, 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.
[0055] Objects and advantages of this disclosure are further
illustrated by the following non-limiting examples, but the
particular materials and amounts thereof recited in these examples,
as well as other conditions and details, should not be construed to
unduly limit this disclosure.
EXAMPLES
[0056] Unless otherwise noted, all parts, percentages, ratios, etc.
in the Examples and the rest of the specification are by weight.
All reagents used in the examples were obtained, or are available,
from general chemical suppliers such as, for example, Sigma-Aldrich
Company, Saint Louis, Mo., or may be synthesized by conventional
methods.
Materials Used in the Examples
TABLE-US-00001 [0057] DESIGNATION DESCRIPTION Melinex PET
polyethylene terephthalate (PET) film, 125 micrometers thick, glass
transition temperature (T.sub.g) of 7.degree. C., obtained from
DuPont Tejin Films, Chester Virginia, as MELINEX ST505 polyester
film Bare PET PET film, 2-mil, (51 micrometers) thickness MICRO 850
Graphite powder, 3-5 micrometers particle size, 13 m.sup.2/g
surface area, 0.088 ohm cm resistivity, obtained from Ashbury
Graphite Mills, Inc., Kittanning, Pennsylvania as MICRO850 graphite
Isopropanol (IPA) solvent, obtained from Aldrich Chemical Company,
Milwaukee, Wisconsin
General Method for Coating Graphite on Substrates
[0058] To make Examples and Comparative Examples described below,
graphite coatings were applied onto PET films by placing a small
amount of MICR0850 on the PET films. The graphite was then rubbed
against the film using a WEN 10PMC 10-inch (25.8-cm) random orbital
waxer/polisher (WEN Products, Elgin, Ill.) 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.
[0059] For Examples EX-1 to EX-12 and Comparative Examples CEX-A to
CEX-C, visible light transmittance was measured using a HAZE-GARD
PLUS haze meter from BYK Additives and Instruments, Wesel,
Germany.
[0060] For Examples EX-6 to EX-8, surface resistivity was measured
using an RC2175 R-CHEK Surface Resistivity Meter form EDTM, Inc,
Toledo, Ohio.
[0061] For Comparative Examples CEX-D to CEX-L, light transmittance
was measured using a Flame-T-XR1-ES spectrophotometer from Ocean
Optics, Dunedin, Fla. These transmittance measurements were
recorded over the range of wavelengths from 325 to 1000 nm and
averaged.
[0062] If thicker coatings were desired, more graphite was applied
and the coating step was repeated.
General Methods for Determining Durability
[0063] The samples prepared according to the Examples and
Comparative Examples, described below, were tested for durability
(resilience of coatings).
[0064] Durability of graphite-coated film specimens was evaluated
using a Model 5750 Linear Abrader from Taber Industries, North
Tonawanda, N.Y. For CEX-A, CEX-B, EX-1 to EX-9, and CEX-D to CEX-L,
a 25 mm flat head on the linear abrader was covered with an L40
WYPALL all-purpose wiper from Kimberly-Clark and saturated with
isopropanol. The films were then subjected to 60 cycles/minute of
abrasion using the 5750 Linear Abrader for a total of one minute,
with a total mass loading of 350 g on the head. 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, Pa., 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,
Pa. 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.
[0065] All reported percent changes in transmittance were
calculations from the following equation:
.DELTA. T ( % ) = T C - T abraded T C - T film .times. 100
##EQU00001##
[0066] Where T.sub.film is the transmittance of the underlying
polymer film, T.sub.C is the transmittance of that same film after
the coating and treatments had been applied, and T.sub.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 transmittance (.DELTA.T, %)
are indicative of higher retention of the total fraction of carbon
on the original film.
EXAMPLES EX-1 to EX-12 and COMPARATIVE EXAMPLES CEX-A to CEX-C
[0067] 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. In all cases of IPL, the
source used was a SINTERON S-2100 Xe flashlamp equipped with Type C
bulb from Xenon Corporation, Wilmington, Mass.
[0068] For CEX-A and EX-1, 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.sup.2.
[0069] CEX-B was prepared in the same manner as CEX-A, except that
the substrate was Melinex PET.
[0070] 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.sup.2.
[0071] 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.sup.2 (EX-3) and 1.0 J/cm.sup.2
(EX-4).
[0072] 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.
[0073] Table 1, below, reports the IPL effects on Bare PET and
Melinex PET.
TABLE-US-00002 TABLE 1 ENERGY DENSITY PER PULSE, EXAMPLE IPL PULSES
J/cm.sup.2 .DELTA.T, % CEX-A 0 0 100.0 EX-1 10 0.4 13.3 CEX-B 0 0
98.3 EX-2 5 0.3 29.9 EX-3 1 0.5 20.9 EX-4 1 1.0 10.5 EX-5 1 1.0
5.4
[0074] 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.sup.2. Table 2, below, reports the change in
transmittance .DELTA.T in %.
TABLE-US-00003 TABLE 2 INITIAL SURFACE RESISTIVITY, EXAMPLE
.OMEGA./square .DELTA.T, % EX-6 250 14.5 EX-7 564 22.3 EX-8 975
23.4
[0075] For EX-9, the substrate coated with graphite was Bare PET.
Prior to exposure to IPL, 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. Additionally, 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.
[0076] 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.
TABLE-US-00004 TABLE 3 EX-9 .DELTA.T, % Masked 99.3 Unmasked
15.0
[0077] For 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.sup.2.
[0078] 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.
[0079] 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.sup.2.
[0080] Table 4, below, reports the change in transmittance .DELTA.T
in %.
TABLE-US-00005 TABLE 4 ENERGY DENSITY PER PULSE, EXAMPLE IPL PULSES
J/cm.sup.2 .DELTA.T, % CEX-C 0 0 79.4 EX-10 10 0.4 5.9 EX-11 10 0.4
11.1 EX-12 5 0.3 8.2
Comparative Examples CEX-D to CEX-L
[0081] For CEX-D to CEX-L, several sheets of Bare PET were coated
with graphite as described above and subjected to several different
methods to induce particle retention.
[0082] For CEX-D to CEX-F, graphite coated Bare PET films were
subjected to blowing heat from a temperature controlled heat gun
(Steinel Electronic Heat Gun, Model HL 2010 E, Type 3482 from
Steinel America Inc., Bloomington, Minn.). With the heat gun
setting on level II, the end of the nozzle was situated 2 inches
(about 5 cm) above and normal to the film surface, which was
secured to the bench top with tape at each end, and applied heat to
the film for a given amount of time.
[0083] For CEX-G to CEX-J, graphite coated Bare PET films were
subject to e-beam irradiation, carried out using an electron beam
system (MODEL CB-300 ELECTRON BEAM SYSTEM from Energy Sciences,
Inc., Wilmington, Mass.). 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.
[0084] For CEX-K to CEX-L, graphite coated Bare PET films were
subject to biaxial strain using a laboratory stretching machine
(Bruckner Maschinenbau, Model Karo IV Biaxial Stretcher from
Bruckner Maschinenbau GmbH & Co. KG, Siegsdorf, Germany). The
machine's oven was set to 150.degree. C., and the sample was placed
in the oven for 5 minutes before being stretched biaxially at a
constant rate of 1% per second.
[0085] 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 (.DELTA.T, %, average normalized change in
transmission). For heat gun, an output greater than 232.degree. 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. For biaxial
stretching, stretching larger than 5% was also applied, but was
found to result in excessive tension of the polymer leading to film
fracture.
TABLE-US-00006 TABLE 5 TEMPERATURE, DURATION, EXAMPLE .degree. C.
minutes .DELTA.T, % CEX-D 232 1 90.4 CEX-E 232 5 89.1 CEX-F 232 10
81.3
TABLE-US-00007 TABLE 6 DOSAGE, EXAMPLE MRad .DELTA.T, % CEX-G 2.5
90.0 CEX-H 5 88.9 CEX-I 10 91.3 CEX-J 20 90.4
TABLE-US-00008 TABLE 7 TEMPERATURE EXAMPLE .degree. C. % STRETCH
.DELTA.T, % CEX-K 150 0 92 CEX-L 150 5 93.8
* * * * *