U.S. patent application number 10/002789 was filed with the patent office on 2002-09-26 for musical instrument strings with polymer treated surface.
Invention is credited to Schlesinger, Todd Evan.
Application Number | 20020136893 10/002789 |
Document ID | / |
Family ID | 27532978 |
Filed Date | 2002-09-26 |
United States Patent
Application |
20020136893 |
Kind Code |
A1 |
Schlesinger, Todd Evan |
September 26, 2002 |
Musical instrument strings with polymer treated surface
Abstract
The performance of musical instrument strings is improved by
treating the strings with a polymer vapor, avoiding problems common
with spray type polymer coatings, extruded or laminate coatings or
wipe-on liquid coatings, including heat damage, imprecise
dimensional control, possible flaking, peeling or easy removal of
the coating or adverse changes or damping of the musical qualities
of the strings. The treatment may be applied either to the core of
said strings, to strands wrapped around the core, or both. The
treatment may be applied either before or after wrapping said
strands around said core.
Inventors: |
Schlesinger, Todd Evan;
(Eldersburg, MD) |
Correspondence
Address: |
Max Stul Oppenheimer
P.O. Box 50
Stevenson
MD
21153
US
|
Family ID: |
27532978 |
Appl. No.: |
10/002789 |
Filed: |
November 26, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60253211 |
Nov 27, 2000 |
|
|
|
60265274 |
Jan 31, 2001 |
|
|
|
60326418 |
Oct 2, 2001 |
|
|
|
60330018 |
Oct 18, 2001 |
|
|
|
Current U.S.
Class: |
428/375 ;
427/255.6; 428/422 |
Current CPC
Class: |
C23C 14/12 20130101;
Y10T 428/2933 20150115; Y10T 428/31544 20150401; G10D 3/10
20130101; C23C 16/30 20130101 |
Class at
Publication: |
428/375 ;
427/255.6; 428/422 |
International
Class: |
C23C 016/00; B32B
015/08; B32B 015/02; B32B 027/02 |
Claims
I claim:
1. A musical instrument string, comprising a core and a polymer
vapor surface treatment adhered to a pre-selected portion of the
surface of said core.
2. A musical instrument string, comprising a core and a polymer
condensed and nucleated on a pre-selected portion of the surface of
said core.
3. A musical instrument string as in claim 1, wherein said
pre-selected portion is substantially the entire length of said
core.
4. A musical instrument string as in claim 2, wherein said
pre-selected portion is substantially the entire length of said
core.
5. A musical instrument string as in claim 1 wherein said polymer
vapor surface treatment comprises PTFE.
6. A musical instrument string as in claim 2 wherein said polymer
condensed and nucleated on said surface is PTFE.
7. A musical instrument string comprising a surface treatment as in
claim 5 wherein said polymer material is vapor deposited PTFE
through plasma sputter deposition, ion beam sputtering, laser
deposition, or hot filament or plasma chemical vapor
deposition.
8. A method of producing a musical instrument string having a
polymeric surface treatment, comprising the steps of: cleaning the
musical instrument string to be treated; providing a suitable vapor
source; placing said musical instrument string and said vapor
source in a vacuum tight vessel; reducing the pressure in said
vessel to a base pressure of about 10-5 Torr or less; and while
maintaining a vacuum of about 20.times.10-3 Torr pressure and
applying power to said source in said vessel, cycling the power to
said source on and off until a desired thickness of PTFE coating is
condensed and nucleated on said musical instrument string.
9. A polymeric treatment applied to a musical instrument string,
produced by the process of claim 8.
10. A musical instrument string having a polymeric surface
treatment wherein said treatment is applied according to the method
of claim 8.
11. A musical instrument string as in claim 10 wherein said musical
instrument string is a core.
12. A musical instrument string as in claim 10 wherein said musical
instrument string is a wound string, comprising a core and at least
one strand wound around said core.
13. A musical instrument string, comprising a core and at least one
strand wound around said core, and a polymer vapor surface
treatment adhered to a pre-selected portion of the surface of said
strand wound around said core.
14. A musical instrument string, comprising a core and at least one
strand wound around said core, and a polymer condensed and
nucleated on a pre-selected portion of the surface of said strand
wound around said core.
15. A musical instrument string as in claim 13, wherein said
pre-selected portion is substantially the entire length of said
strand wound around said core.
16. A musical instrument string as in claim 14, wherein said
pre-selected portion is substantially the entire length of said
strand wound around said core.
17. A musical instrument string as in claim 13 wherein said polymer
vapor surface treatment comprises PTFE.
18. A musical instrument string as in claim 14 wherein said polymer
condensed and nucleated on said surface is PTFE.
19. A musical instrument string comprising a surface treatment as
in claim 17 wherein said polymer material is vapor deposited PTFE
through plasma sputter deposition, ion beam sputtering, laser
deposition, or hot filament or plasma chemical vapor
deposition.
20. A musical instrument string, comprising a core and at least one
strand wound around said core, and a polymer vapor surface
treatment adhered to a pre-selected portion of the surface of both
said core and said strand wound around said core.
Description
PRIORITY
[0001] This application is entitled to and claims the benefit of
priority from the following United States Provisional
Applications:
[0002] 60/253,211 for "Improved Strings for Musical Instruments"
filed Nov. 27, 2000
[0003] 60/265,274 for "Improved Strings for Musical Instruments"
filed Jan. 31, 2001
[0004] 60/326,418 for "Musical Strings" filed Oct. 2, 2001
[0005] 60/330,018 for "Vapor Deposited Polymer Coating" filed Oct.
18, 2001
FIELD AND BACKGROUND OF THE INVENTION
[0006] 1. Field of the Invention
[0007] The present invention relates in general to polymer vapor
surface treatments and coatings, in particular to polymer vapor
surface treatments and coatings as applied to musical instrument
strings; even more specifically, it relates to
polytetrafluoroethylene ("PTFE") polymer vapor surface treatments
and coatings applied to musical instrument strings.
[0008] 2. Background Information
[0009] The invention described and claimed herein comprises a vapor
phase polymeric surface treatment. One specific application of such
a surface treatment is applied to musical instrument strings.
Examples of such strings are guitar, violin, cello, bass, piano and
harp strings.
[0010] Surface coatings, and surface treatments, are well-known in
the art. As used herein, surface coating means an attached laminate
or jacket, positioned on the substrate, while surface treatment
means a modified surface region of the substrate which is in fact
part of the substrate.
[0011] A musical instrument string typically comprises a core of
material and optionally additional strands of the same or other
material wound around the core. The composition and dimensions of
the core and the optional windings are chosen so as to produce the
desired tones when the string is caused to vibrate.
[0012] U.S. Pat. No. 4,945,856 deals with the vapor deposition of
parylene polymer in low vacuum. This material has been used in the
electronics and medical area, but it has several times higher
friction coefficient as does PTFE. The process is performed in a
lesser degree of vacuum, which does not offer the same purity as
high vacuum processes. The level of adhesion of this coating does
not lend itself to applications where surface abrasion (strumming)
is an issue as it can fray and delaminate fairly easily from the
coated article. There exist stronger binding forces within the
coating itself than between the coating and substrate. It is
believed that this effect is responsible for the way in which a
parylene coating can be peeled from the substrate, whereas the PTFE
polymer vapor surface treatment can not.
[0013] U.S. Pat. No. 3,767,559 deals with RF sputter deposition of
PTFE as an improvement over DC means, which are not applicable to
insulators such as PTFE, but does not mention the use as a coating
on musical strings.
[0014] U.S. Pat. No. 4,539,228 deals with extending the life of
musical instrument strings through the application of PTFE in an
oil lubricant. While some of the benefits of applying PTFE to a
musical string are gained, the material is not adhered to the
surface in the same way that a vapor deposited polymer is condensed
and nucleated onto the surface.
[0015] U.S. Pat. No. 5,578,775 discloses a musical instrument
string having an inner bundle embedded in a mantle of precious
metal and an abrasive resistant treatment of short regions of the
string (those which are either struck while playing or which
contact the instrument) and discloses surface hardening using
phosphate coating, vapor plating, flame coating or ion plating.
[0016] U.S. Pat. No. 5,883,319 deals with the bonding of a
GORETEX(.TM.) expanded PTFE ("ePTFE") gauze to the surface of the
wound type of musical instrument strings, using an adhesive. The
gauze sheet is then covered with a heat shrink or polymer
jacket.
[0017] U.S. Pat. No. 5,888,591 teaches deposition of PTFE using
Chemical Vapor Deposition (CVD), with no specific mention of use
for musical strings. The preferred method in the current invention
uses Physical Vapor Deposition (PVD) which has been documented to
result in a harder, more wear resistant polymeric material,
possibly attributed to the higher degree of cross linking of the
polymeric material resulting from PVD processing.
[0018] A general reference describing deposition techniques and
alternatives is "Plasma Deposition and Treatment of Polymers", ed.
W. W. Lee, R. d'Agostino, and M. R. Wertheimer, ISBN 1-55899-450-5,
published by Materials Research Society.
[0019] Spray type coatings have been applied to musical instrument
strings, but can affect the musical quality as they change the
mechanical properties of the string due to excessive coating
thickness, and the attached laminate being distinct from the
substrate, causing deadening of the musical sound. The "Black
Maxima" TEFLON (.TM.) spray coated string had been previously
marketed by Maxima, approximately 10 years ago. Applicants believe
that this product was discontinued as the coating would become
unattached from the string, and degrade musical performance. Also,
the high temperature oven baking processes used to cure spray type
coatings onto the surface can harm the base metal. Oil based and
other wipe-on type coatings are not well adhered to the substrate,
and will offer only short term benefits. Still other types of
extruded coatings or jacketed coatings can adversely affect sound
quality, due to the damping of the sound vibrations and subsequent
muffling of the sound.
SUMMARY OF THE INVENTION
[0020] The invention comprises polymer vapor treatment of musical
instrument strings. The performance of musical instrument strings
is improved by treating the strings with a polymer vapor, avoiding
problems common with spray type polymer coatings, extruded or
laminate coatings or wipe-on liquid coatings, including heat
damage, imprecise dimensional control, possible flaking, peeling or
easy removal of the coating or adverse changes or damping of the
musical qualities of the strings.
[0021] The treatment may be applied either to the core of said
strings, to strands wrapped around the core, or both. The treatment
may be applied either before or after wrapping said strands around
said core.
[0022] Among the advantages of the invention, polymer vapor treated
strings offer better performance than untreated strings, having
lower friction and a smoother sensation while playing. The
polymeric treatment provides lessened tarnish and corrosion of the
strings from finger perspiration and prevents contaminants from
attaching to the surface, which can degrade sound quality.
[0023] Due to the manner in which the vapor condenses and nucleates
onto the surface, and fills and attaches to micro-voids and surface
porosity, there is the additional advantage of reduced break-in
time needed to achieve the optimum musical properties of the
string. This is attributed to the lubricating action of the surface
treatment on the string vibrations as the mechanical waves cause a
frictional drag within surface metallurgical cracks, which are in
motion during the harmonic vibrations. In contrast, other processes
rely on mechanical bonding or adhesives to attach the thicker
polymer jackets or other macroscopic laminates, which can cause
additional deadening of the sound. Therefore, using the disclosed
invention, improved sound quality is realized as soon as the
strings are installed on the instrument and the polymer vapor
surface treatment process will not adversely change the sound
quality of the strings as do other coating processes.
[0024] Another advantage of polymer vapor treatment of musical
strings is that both the wound strings and the single strand
strings are treated, resulting in consistent performance and
surface feel while playing the instrument. Coating of only wound
strings can result in uneven feel and sound while playing from
treated to untreated strings. Musicians comment that when playing
coated strings which have 2 or 3 strings uncoated out of 6
(guitar), there is a distinct difference in feel when playing
across from coated to uncoated, and vice versa. Several citations
of musician's comments have stated that either a distinct "hitting
the brakes" or, conversely, "Van Halen" effect (sliding) was
experienced when using coated strings offering only a fraction of
the total number of strings in the set with a coating applied, as
is offered by competitive processes.
[0025] Competitive coating processes are not adapted well to
coating the higher frequency (treble) strings. Both a difficulty in
adhering the thicker coated layer to the treble strings, and also
the undesirable effect of damping of the vibration (and deadening
of the sound) is evident the most in the high frequency vibration
of the treble strings. Therefore, only 3 or 4 out of 6 strings
(guitar) are coated in the competitive processes. There also has
been some issue with fraying of the adhered type of coatings after
time.
[0026] Vapor deposit is preferable to other methods (such as spray
coating) due to the low temperature process and better dimensional
control available from vapor processes. The nature of the polymer
vapor surface treatment, nucleated onto the surface, does not flake
or peel from the substrate as do thicker coatings or laminates.
[0027] The precise dimensional control of vapor deposition also
provides minimal deviation in the uniformity of the diameter of the
treated wire; this is critical in the world of stringed musical
instruments where even minute variations of string diameter along
the length of the wire can result in out-of-tune harmonic
vibrations of the string, causing diminished sound quality.
[0028] The use of PTFE polymer vapor surface treatment of musical
instrument strings provides improved surface properties of the
strings with no adverse effects to the musical properties.
[0029] Frequent comments from musicians using competitive "coated"
strings is that while they enjoy the benefit of improved feel and
longer lasting strings, there is a distinct deadening of the sound.
The current invention provides the benefits of improved
playability, extended life, reduced break-in period, with no
deadening of the sound, or even improved sound timbre and tone
detected by some musicians.
[0030] It is believed that the polymer vapor process provides a
method for treatment of the microscopic surface features of the
string with PTFE nucleates. This serves to provide a treated
surface, rich in polymeric material, with no distinct junction
between coating and substrate as exists in competitive products.
The equations governing mechanical vibration of 2 separate entities
will have an increased damping factor as the 2 entities vibrate out
of phase with respect to one another. This effect is more
pronounced at higher frequencies. In a polymer vapor treated string
surface, the damping factor is minimized due to reduction of out of
phase vibration. The disclosed invention thus allows treatment of
all the strings, high frequency (treble) and lower frequency (bass)
alike, constituting a "set" of strings.
[0031] Acoustic measurements of the increased damping present in
competitive "laminated" or "coated" products compared to a polymer
vapor treated string bear this out.
[0032] It is an object of the invention to provide a novel
polymeric vapor surface treatment.
[0033] It is another object of the invention to form a vapor of
polymer material in a vacuum environment and condense this vapor
onto the surface of both wound and single-stranded musical
instrument strings, resulting in nucleated polymer material on the
string surface.
[0034] It is another object of the invention to apply to wound and
single-stranded musical instrument strings such a surface treatment
that does not adversely effect the musical properties of the
strings.
[0035] It is another object of the invention to apply such a
treatment to substantially the entire length of a musical
instrument string.
[0036] A further object of the invention is to provide a polymeric
surface treatment comprised of vapor deposited PTFE nucleates
applied to musical instrument strings. A base layer of corrosion
resistant metal such as gold, titanium, chromate conversion coating
or other material may also be used, resulting in further improved
mechanical properties and wear resistance and corrosion
resistance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] The foregoing and still other objects of this invention will
become apparent, along with various advantages and features of
novelty residing in the present embodiments, from study of the
following drawings, in which:
[0038] FIG. 1 is a schematic diagram of the process of treating
musical instrument strings with a PTFE polymer vapor, using the
plasma sputter deposition method.
[0039] FIGS. 2, 3, 4, and 5 show alternative methods of polymer
vapor deposition used to treat the surface of musical instrument
strings. These methods are Ion Beam Sputtering (FIG. 2), Laser
Deposition (FIG. 3), Plasma Chemical Vapor Deposition (FIG. 4), and
Hot Filament Chemical Vapor Deposition (FIG. 5).
[0040] FIG. 6 is a schematic drawing showing a single-strand
musical instrument string which has been treated with vapor
deposited polymer nucleate.
[0041] FIGS. 7 through 9 show scanning Electron Microscope
Photographs depicting the difference between a polymer vapor
treated surface and other types of coatings.
[0042] FIG. 7 shows a polymer vapor treated wire.
[0043] FIG. 8 shows a spray coated wire.
[0044] FIG. 9 shows a polymer laminate on a wire.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0045] Referring to the drawings, the invention is a PTFE vapor
surface treatment method and composition, illustrated by
application to musical instrument strings.
[0046] Vapor processes include several types of related methods
whereby a vapor phase of PTFE polymer is created in a vacuum
chamber and then allowed to condense onto the surface of a musical
instrument string, resulting in the surface being treated with PTFE
nucleated material. This treated musical instrument string, with
nucleated PTFE polymer vapor condensed onto the surface, has many
advantages over untreated strings, or other technologies using
attached polymer films or porous structures, or spray type
coatings. The surface being treated via exposure to vapor phase
polymeric material shows distinct advantages over attached or
adhered or laminated outer jackets or layers. One attribute of this
effect is realized in the type of mechanical vibrations produced by
a vapor polymer treated string versus a coated or jacketed or
laminated string. This is evident in the quality of the musical
sound produced by the strings, and the underlying microscopic
mechanical phenomena resulting in virtually zero sound deadening as
is caused by macroscopic laminates and coatings on musical strings.
The polymer vapor surface treatment results in a polymer rich
surface with no distinct interface between the substrate and the
surface coating, as is evident in macroscopic laminates and
coatings.
[0047] The invention may be implemented by plasma sputter
deposition or other vapor deposition process applied to musical
instrument strings using the following steps.
[0048] 1. Cleaning the parts to be treated, for example by
ultrasonic cleaning in detergent and then in acetone; optionally,
immediately before the process begins, the parts may also be
treated in a vacuum chamber by applying RF power directly to the
substrate holder in order to plasma etch the parts and remove any
residual contamination. This plasma cleaning also increases
adhesion of the surface treatment.
[0049] 2. The pressure in the vessel (3) is reduced to a base
pressure of about 10-5 Torr or less. This may be accomplished using
a mechanical vacuum pump (8), then a cryogenic pump (9). Additional
pumping and removal of process contaminants during deposition may
be achieved through the use of an optional cryogenic trap (20)
using liquid nitrogen.
[0050] 3. Process gas (14) can be selected from argon, nitrogen,
(nitrogen is preferable) is flowed into the vessel (3) using a gas
flow controller (13) to create an initial vacuum of about
2.times.10-2 Torr pressure or less and to maintain a vacuum of
about 2.times.10-2. A flow rate of about 25 sccm has been found
satisfactory. Alternatively, fluorocarbon gases are used in the
plasma CVD and hot filament CVD processes.
[0051] 4. In the RF sputtering method, an RF power supply (10)
applies power to a suitable source such as a cathode assembly (11)
onto which a PTFE sheet (12) is mounted, so as to ignite a plasma
in the vessel (3). RF power at frequencies of 13.56 MHz and 500
Watts power have been found satisfactory with a 17".times.5" PTFE
sheet.
[0052] 5. This results in a plasma glow discharge which produces a
PTFE vapor within the vacuum vessel. The vapor is allowed to
condense and nucleate onto the surface of the musical instrument
string. The RF power is kept on until the desired amount of polymer
material is condensed and nucleated on the surface. It has been
found preferable to run the deposition process in cycles (e.g.,
three minutes with plasma on followed by three minutes with plasma
off)so as to allow parts adequate time to cool to a desired
temperature range and avoid overheating. The surface treated layer,
normally in the range of about 0.1 to 10 microns, is normally
achieved in a total of between three and thirty cycles.
[0053] 6. Schematic diagrams of alternative methods used to form a
vapor of PTFE polymer show ion beam sputtering, laser deposition,
or flowing of a precursor fluorocarbon gas into the vessel in the
presence of a heating filament or RF energy.
[0054] 7. In all of the above processes a vapor phase of polymer
material is created, and then allowed to nucleate onto the surface
of the musical string resulting in polymer material condensed and
nucleated on the surface.
[0055] The above process may be altered to use polymers other than
PTFE. Polymers including polyimide, polyethylene, and acrylics have
been successfully vapor deposited.
[0056] In all of the described vapor deposition methods, a vapor of
polymer is created in a vacuum environment. This vapor is then
allowed to condense and nucleate on the surface of a musical
instrument string. The result is a musical instrument string which
has a polymer condensed and nucleated on the surface.
[0057] The differences among the five outlined processes is the
means by which the vapor phase of polymer material is formed. In
the plasma sputter deposition process (FIG. 1), RF plasma is
configured so as to have ions and energetic particles contained in
the plasma accelerated into a polymer source material so as to
eject microscopic polymer particles into a vacuum environment,
forming a vapor of polymer material.
[0058] In Ion beam sputtering (FIG. 2) the ejected polymer
particles are formed by an ion beam being directed toward the
surface of the polymer source material. In Laser deposition (FIG.
3) a pulsed beam of laser light is incident on the surface of the
polymer source material, causing polymer particulate to be ablated
off into a vapor phase. In the Plasma chemical vapor deposition
(FIG. 4) and the Hot filament chemical vapor deposition method
(FIG. 5) a precursor gas containing the desired elements to be used
to form the vapor phase is admitted into the vacuum vessel in a
controlled manner. A source of electromagnetic energy (Plasma CVD)
or thermal energy (hot filament CVD) is used to excite the gas
precursor which causes the gas molecules to react and form polymer
vapors which are then allowed to condense and nucleate on the
surface of the musical instrument string.
[0059] Other variations of the process can also be implemented to
form a vapor phase of polymer material in a vacuum chamber, and
subsequently allow the vapor to condense and nucleate on the
surface of the musical instrument string. A general reference
describing deposition techniques and alternatives is "Plasma
Deposition and Treatment of Polymers", ed. W. W. Lee, R.
d'Agostino, and M. R. Wertheimer, ISBN 1-55899-450-5, published by
Materials Research Society.
[0060] Additional improvement to the effects of the PTFE polymer
vapor surface treatment on the strings can be gained through the
use of a chemical conversion layer, such as a chromate conversion
process. This process reacts a thin layer of the metal surface of
the string to form a chromate compound. In and of itself this layer
has increased tarnish resistance. By using it in conjunction with
the PTFE polymer vapor surface treatment, a synergistic enhancement
to the performance of the musical strings is gained. This is
believed to be due to the microscopic roughening caused by the
chromate to allow the vapor deposited nucleates to "key" into the
surface, further extending the longevity of the PTFE polymer vapor
surface treatment.
[0061] Further variation in tailoring the properties of PTFE
polymer vapor surface treatments include the following. The control
of deposition parameters including cooling of the substrate below 0
deg C., along with high plasma density, and oblique angle of the
source with respect to the substrate can be advantageously used to
control porosity (pore size and pore fraction) of the nucleated
polymeric material. This porosity can be utilized to house an
additional material, such as a low friction liquid lubricant, or
other substance. The result is an adhered layer of a liquid
lubricant on the surface of the string, which provides a lowered
coefficient of friction if desired. Such a liquid lubricant, if
used alone, would not have the same amount of binding to the
surface, and would mainly be held on by surface tension alone. The
nucleated polymer vapor material has chemical and physical binding
to the surface.
[0062] The control over porosity may also be used to modify the
mechanical properties of the polymer. Porous PTFE bulk material,
created through an entirely different mechanical stretching
process, has been the subject of a great deal of interest. GORETEX
(.TM.) has done much work in the field of mechanically expanded
"e-PTFE". Porous PTFE vapor surface treatments are expected to also
have a great many new applications.
[0063] Higher substrate temperatures, above 0 deg C., and normal
(perpendicular) angle of source with respect to substrate is
favorable for a more featureless structure of the surface, with
little porosity.
[0064] The current invention may be used to treat the winding wire
or core wire prior to the winding wire being wrapped around the
core wire. Alternatively, the wrapped string may be treated as a
unit, for simplified processing.
[0065] While benefits may be produced by treating certain
pre-selected portions of a musical instrument string (for example,
those portions which are plucked, strummed or struck while playing,
or those portions which are in contact with the instrument), in the
preferred embodiment, substantially the entire length of the string
is treated. Treating substantially the entire length produces
additional benefits in uniformity, predictability and persistence
of tone qualities.
EXPERIMENTAL SETUP AND RESULTS
[0066] The above steps were carried out using the following
equipment in a setup as in FIG. 1 (all components not specified
below were standard, off the shelf, laboratory components):
[0067] 1. component to be treated (e.g., a musical instrument
string)
[0068] 3. vacuum vessel
[0069] 8. mechanical vacuum pump (Welch model no. 1398 or
equivalent)
[0070] 9. cryogenic vacuum pump (CT Instruments model no. CT-10 or
equivalent)
[0071] 10. RF power supply (ERA, Inc. model no. 7910 or
equivalent)
[0072] 11. cathode assembly (Aireco-Temescal Cathode Assembly model
no. HRC-817 or equivalent)
[0073] 12. PTFE material (pure, virgin PTFE)
[0074] 13. In the alternate methods, an ion source (Commonwealth
Scientific brand, cold cathode type or Kaufman type, or
equivalent), or a laser (an excimer laser, a Nd-YAG laser or other
common types of commercially available lasers are suitable), or
variable voltage electric heating filament or RF energy (item 10)
is suitable as input energy source.
[0075] Referring to the scanning electron microscope images of
FIGS. 7-9, some of the advantages over prior art techniques may be
seen. FIG. 7 shows a polymer vapor treated wire, treated using the
technique of the invention. As can be seen, the surface is smooth
and well-adhered compared to FIGS. 8 and 9. FIG. 8 shows a spray
coated wire, and FIG. 9 shows a polymer laminate on a wire. It can
be seen that the spray coated wire of FIG. 8 and the polymer
laminated wire of FIG. 9 exhibit coating delamination and flaking,
and the spray coated wire of FIG. 8 also shows heat damage
characteristic of high temperature bake out of spray coatings.
[0076] In order to test the benefits of the invention, the
following experiment was carried out. Samples of musical instrument
strings (Martin Guitar Phosphor Bronze Acoustic Guitar Strings)
were obtained, and half of them were treated as follows: An
immersion cleaning in acetone was performed to remove any residual
oils. The strings were placed in a vacuum deposition system, and
treated with PTFE polymer vapor on one side. The parts were rotated
180 degrees, and then the opposite sides were treated.
[0077] The treated and untreated samples were submitted to an
independent testing laboratory, which conducted tests for corrosion
resistance using a humidity test and a hydrogen sulfide vapor
test.
[0078] The humidity test consisted of exposing treated and
untreated strings to a relative humidity of 90% at 45 degrees C.,
for varying times up to 14 days. The hydrogen sulfide vapor test
consisted of exposing the strings to a vapor of hydrogen sulfide
gas, for periods of up to 48 hours.
[0079] It was concluded that the treated wound strings were
noticeably less tarnished and corroded than the wound untreated
strings. The treated strings remained a bright bronze color, while
the untreated strings became discolored from the hydrogen sulfide
gas. The untreated single-strand strings developed spots from the
humidity exposure, where the treated strings did not.
[0080] While illustrated with respect to plasma sputter vapor
deposition of PTFE, the invention may be applied using any
similarly vaporizable polymer with the same techniques, modified in
a manner which would be known to one skilled in the art.
[0081] Therefore, while specific embodiments of the invention have
been shown and described in detail to illustrate the application of
the principles of the invention, it will be understood that the
invention may be embodied otherwise without departing from such
principles and that various modifications, alternate constructions,
and equivalents will occur to those skilled in the art given the
benefit of this disclosure.
* * * * *