U.S. patent application number 11/370126 was filed with the patent office on 2007-09-13 for exterior coatings for golf balls.
Invention is credited to Jeffrey D. Chinn, Peter Pui-Wa Yang.
Application Number | 20070213143 11/370126 |
Document ID | / |
Family ID | 38479638 |
Filed Date | 2007-09-13 |
United States Patent
Application |
20070213143 |
Kind Code |
A1 |
Chinn; Jeffrey D. ; et
al. |
September 13, 2007 |
Exterior coatings for golf balls
Abstract
Improved golf ball exterior coatings which are used to create an
extremely uniform hydrophobic or hydrophilic exterior surface on
the golf ball. When the surface of the golf ball is hydrophobic, it
tends to repel water, and this reduces drag on the golf ball
surface as the golf ball travels through the air. When the surface
of the golf ball is hydrophilic, the surface of the golf ball wets
uniformly and the ball rolls straighter on a wet green, as the
forces acting on the ball are more uniform. The hydrophobic or
hydrophilic exterior coating is applied to the golf ball using
vapor-phase deposition in instances where strict control over
coating thickness uniformity, and/or reduced surface roughness is
desired.
Inventors: |
Chinn; Jeffrey D.; (Foster
City, CA) ; Yang; Peter Pui-Wa; (Palo Alto,
CA) |
Correspondence
Address: |
SHIRLEY L. CHURCH, ESQ.
P.O. BOX 81146
SAN DIEGO
CA
92138
US
|
Family ID: |
38479638 |
Appl. No.: |
11/370126 |
Filed: |
March 7, 2006 |
Current U.S.
Class: |
473/351 ;
473/378 |
Current CPC
Class: |
B05D 5/08 20130101; A63B
37/0022 20130101; C23C 16/401 20130101; B05D 5/04 20130101; B05D
1/60 20130101; B05D 3/144 20130101; A63B 45/00 20130101 |
Class at
Publication: |
473/351 ;
473/378 |
International
Class: |
A63B 37/00 20060101
A63B037/00; A63B 37/14 20060101 A63B037/14 |
Claims
1. An exterior coating for a golf ball which renders the exterior
surface of said golf ball hydrophobic or hydrophilic, wherein said
coating thickness is uniform over said golf ball surface within
.+-.2 nm.
2. An exterior coating for a golf ball in accordance with claim 1,
wherein said coating provides a hydrophobic surface on said golf
ball.
3. An exterior coating for a golf ball in accordance with claim 2,
wherein said coating includes at least two layers, where the
interior layer in contact with the golf ball cover layer is an
oxide bonding layer, and the exterior layer, which forms an
exterior surface of the coating is an organic-comprising
hydrophobic layer.
4. An exterior coating for a golf ball in accordance with claim 2,
wherein said coating is a single organic layer, where the organic
layer was generated from a precursor comprising at least one
amine-functionalized terminal group and fluorine-containing
terminal groups, where the at least one amine-functionalized
terminal group was reacted with the golf ball cover layer and
wherein the fluorine-containing groups are presented on an exterior
surface of the golf ball.
5. An exterior coating for a golf ball in accordance with claim 3,
wherein said exterior hydrophobic layer presents fluorine atoms at
the surface of the golf ball.
6. An exterior coating for a golf ball in accordance with claim 3,
wherein said exterior coating exhibits a surface roughness ranging
from about 3 nm RMS to about 16 nm RMS.
7. An exterior coating for a golf ball in accordance with claim 3
or claim 4, wherein said exterior coating overall thickness ranges
from about 1.5 nm to about 500 nm.
8. An exterior coating for a golf ball in accordance with claim 3
or claim 4, wherein said exterior layer is formed from a SAM.
9. An exterior coating for a golf ball in accordance with claim 2,
wherein said water contact angle ranges from about 100.degree. to
about 125.degree..
10. An exterior coating for a golf ball in accordance with claim 1,
or claim 2, or claim 3, or claim 4, applied over a golf cover layer
surface comprising a polymer selected from the group consisting of
ionomers, polystyrene, polybutadiene, isoprene, polyurea,
polyurethane, poly-para-xylene, poly-chloro-para-xylene,
poly-dichloro-para-xylene, polyvinylidene chloride,
polyvinylchloride, polyvinylchloride, polyacrylonitrile,
fluorohalocarbons, fluorinated ethylene propylene copolymer,
polytetrafluoroethylene, polyvanilidine fluoride, polyvinyl
fluoride, perfluoroalkoxy resins, polyethylene, polyethylene
terephthalate, polypropylene high density polyethylene, polyimide,
polyamide, acrylic, and combinations thereof.
11. An exterior coating for a golf ball in accordance claim 1,
wherein said coating provides a hydrophilic surface on said golf
ball.
12. An exterior coating for a golf ball in accordance with claim
11, wherein said coating comprises an oxide layer.
13. An exterior coating for a golf ball in accordance with claim
12, wherein said coating is an oxide layer.
14. An exterior coating for a golf ball in accordance with claim
13, wherein said coating thickness ranges from about 15 nm to about
500 nm.
15. An exterior coating for a golf ball in accordance with claim
14, wherein said exterior coating surface roughness ranges from
about 1 nm RMS to about 10 nm RMS.
16. An exterior coating for a golf ball in accordance with claim
12, wherein said coating also includes an organic layer which is
bonded to said oxide layer and which presents a hydrophilic
exterior surface.
17. An exterior coating for a golf ball in accordance with claim
16, wherein said organic layer comprises PEG.
18. An exterior coating for a golf ball in accordance with claim
17, wherein said exterior coating exhibits a surface roughness
ranging from about 3 nm RMS to about 16 nm RMS.
19. An exterior coating for a golf ball in accordance with claim
16, wherein said organic layer thickness ranges from about 1.5 nm
to about 25 nm.
20. An exterior coating for a golf ball in accordance with claim
16, wherein said organic layer is formed from a SAM.
21. An exterior coating for a golf ball in accordance with claim
11, wherein said water contact angle ranges from about 5.degree. to
about 60.degree..
22. An exterior coating for a golf ball in accordance with claim
11, or claim 12, or claim 16, applied over a golf cover layer
surface comprising a polymer selected from the group consisting of
ionomers, polystyrene, polybutadiene, isoprene, polyurea,
polyurethane, poly-para-xylene, poly-chloro-para-xylene,
poly-dichloro-para-xylene, polyvinylidene chloride,
polyvinylchloride, polyvinylchloride, polyacrylonitrile,
fluorohalocarbons, fluorinated ethylene propylene copolymer,
polytetrafluoroethylene, polyvanilidine fluoride, polyvinyl
fluoride, perfluoroalkoxy resins, polyethylene, polyethylene
terephthalate, polypropylene high density polyethylene, polyimide,
polyamide, acrylic, and combinations thereof.
23. A method of applying an exterior coating over a golf ball
surface, wherein said exterior coating is deposited using vapor
deposition.
24. A method in accordance with claim 23, wherein said exterior
coating is deposited to have a thickness ranging from about 2 nm to
about 2,000 nm.
25. A method in accordance with claim 23, wherein said exterior
coating includes at least two vapor deposited layers, wherein the
interior layer in contact with the golf ball cover layer is a vapor
deposited oxide bonding layer, and the exterior layer which makes
up the exterior surface of the coating is a vapor deposited
organic-comprising layer.
26. A method in accordance with claim 25, wherein said vapor
deposited organic-comprising layer presents an exterior surface on
the golf ball which is hydrophilic.
27. A method in accordance with claim 26, wherein said vapor
deposited organic-comprising layer presents an exterior surface on
the golf ball which is hydrophobic.
28. A method in accordance with claim 23, wherein prior to vapor
deposition of said exterior coating, a surface of said golf ball to
which the exterior coating is to be applied is treated with an
oxygen-comprising plasma.
Description
[0001] This application is related to a series of patent
applications pertaining to the application of thin film coatings on
various substrates, particularly including U.S. patent application
Ser. No. 10/862,047, filed Jun. 4, 2004, and entitled "Controlled
Deposition of Silicon-Containing Coatings Adhered by an Oxide
Layer"; and, U.S. patent application Ser. No. 10/996,520, filed
Nov. 19, 2004, and entitled "Controlled Vapor Deposition of
Multilayered Coatings Adhered by an Oxide Layer". Both of these
applications are hereby incorporated by reference in their
entireties.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention pertains to golf balls coated with
exterior thin film coatings which affect the performance of the
golf ball during play.
[0004] 2. Brief Description of the Background Art
[0005] This section describes background subject matter related to
the invention, with the purpose of aiding one skilled in the art to
better understand the disclosure of the invention. There is no
intention, either express or implied, that the background art
discussed in this section legally constitutes prior art.
[0006] A multitude of studies have been conducted with respect to
aspects of the composition and shape of the golf ball which affect
it's performance. One of the more interesting is an article
entitled "A St. Mary's Project: The Aerodynamics of Golf Ball
Flight", by Kevin E. Warring, Department of Physics, St. Mary's
College of Maryland, St. Mary's City, Md., published in the Spring
of 2003. This article provides an introduction to Fluid Dynamics
which affect golf ball flight; the dimpled golf ball and drag; the
Magnus force (a major force acting on the golf ball due to its
spin); and, the modeling of golf ball flight in general. The author
explains how to predict the trajectory of a golf ball give its
initial launch angle, velocity and spin rate. The article discusses
applications of the principles discussed to golf ball design.
[0007] A web site at www.indoindians.com/golfbcore.htm, in January
2006 contained an article titled "Dimples Drive Drag Out of Golf
Balls", this article explains that at airspeed, sticky air slows a
ball down substantially. The ball is said to get wet as it travels
through air, so that the surface of the ball is referred to as a
"wetted surface". The use of dimples on the ball surface is said to
make air molecules in the boundary layer adjacent the golf ball
surface tumble, so that the boundary layer becomes turbulent. The
article teaches that when the boundary layer is turbulent and thin,
the ball loses less energy to the free stream air and the drag on
the ball is lower. In addition to the discussion of the golf ball
in flight, there is a presentation about what happens to a golf
ball after it sits at the bottom of a pond. A study was conducted
with respect to balls which were permitted to sit in water at
temperatures ranging from 36 to 70.degree. F. for a period of six
months. The balls were tested using a robotic hitting machine. The
average carry, and roll for the new balls was about 251 yards. The
average carry and roll for balls that had been in the water for
eight days was about 236 yards. After three months, the average
carry and roll had decreased to about 226 yards, and after six
months, the average carry and roll was about 225 yards. This may be
viewed as a six yard loss of distance after eight days, a 12 yard
loss after three months, and a 15 yard loss after six months.
[0008] U.S. Pat. No. 6,509,410 to Ohira et al., issued Jan. 21,
2003, describes an aqueous coating composition for a golf ball. The
aqueous coating composition is said to form a high crosslink
density owing to the high hydroxyl value, to contain. The coating
produced is said to have high impact resistance, abrasion
resistance, contamination resistance, etc. which are equivalent to
films produced from organic solvent type coatings. The coating
formed is said to be free from cracking or film peeling when hit by
a golf club; is said to be low in scratch, abrasion and
contamination with grass sap, and is said to provide a coated golf
ball which retains gloss and fine appearance.
[0009] U.S. Pat. No. 6,806,347 to Hogge et al., issued Oct. 19,
2004, describes golf balls with a thin moisture vapor barrier
layer. The golf ball comprises a core, a cover, and at least one
water vapor barrier layer, where the water vapor barrier layer
comprises at least one layer formed from poly-para-xylene and its
derivatives. The patent discusses WVB (water vapor barrier) layers
and WVT (water vapor transmission) rates. The thin moisture vapor
barrier layer described, which is formed from poly-para-xylene, and
its derivatives. Parylenes are selected as materials of choice to
form the thin WVB layers, particularly when the parylene is
halogenated to include a group VIIA element. The group VIIA element
may be fluorine, chlorine, bromine, iodine, or astatine. The
preferred element is chlorine. The WVB layer comprising parylenes
is typically formed using vapor deposition polymerization at a
steady rate. The thickness of the parylene-based WVB layer is said
to be controllable at any desired nominal thickness because the WVB
layer is formed via vapor deposition polymerization at a steady
rate. Thickness of the layer commonly ranges from about 0.025 .mu.m
to about 75 .mu.m. The thickness is preferably from about 1 .mu.m
to about 25 .mu.m, and most preferably from about 3 .mu.m to about
10 .mu.m. One or more of the thin WVB layers may be disposed
between the golf ball core and the cover. Substrates such as golf
ball cores and golf ball sub-assemblies are prepared for parylene
coating by cleaning off oils and other surface contaminants. The
substrate may then be pre-treated by application of a
"multi-molecular" layer of organosilane to promote adhesion of the
parylene coating. The parylene precursor, a granular white powder,
is vaporized at about 150.degree. and 1.0 Torr vacuum in a
vaporizer chamber. The resulting gaseous form of stable dimeric
di-para-xylene is further heated in a pyrolysis chamber to about
680.degree. C. at about 0.5 Torr vacuum, to directly break the two
methylene-methylene bonds and yield stable monomeric diradicals,
para-xylene, also in gaseous form. The monomer is then sent to the
deposition chamber at ambient temperature and about 0.1 torr
vacuum. The resulting parylene coating is said to be very stable
and extremely resistant to moisture vapor permeation, chemical
attacks and hydrolytic breakdown.
[0010] U.S. Patent Application Publication No. US 2005/0009638, of
Wu et al., published Jan. 13, 2005, describes golf ball layers
formed of polyurethane-based and polyurea-based compositions
incorporating block copolymers. The golf balls typically comprise
three layers. The core layer is typically formed from a thermoset
material or a thermoplastic material. When the cores are formed
from a thermoset material, compression molding is typically used to
form the core. When the core is thermoplastic, the cores may be
injection molded. The intermediate layer may be formed from any
suitable method known to those of ordinary skill in the art, and
may be formed by blow molding. The outer layer is generally a
dimpled cover layer formed by injection molding, compression
molding, casting, vacuum forming, powder coating, and the like.
[0011] The published application discusses a large amount of
material, however, based on the claims, the focus appears to be a
golf ball comprising a core and a cover, where the cover is formed
from a composition comprising a prepolymer and a curing agent,
where the prepolymer includes a first prepolymer and a block
copolymer having functional groups at each terminal end, where the
composition comprises a hydrophobic A.sub.x-B.sub.y-A.sub.z block
capped between iso-cyanate groups, wherein x, y, and z are
independently 1 or greater. The block is typically a
styrene-butadiene block. The functional groups at the terminal ends
of the block are selected from groups such as hydroxy groups, amino
groups, thiol groups, epoxy groups, anhydride groups and
combinations of these. The terminal groups are designed to provide
a cover which is water resistant. The cover material was molded
onto wound cores, and a "conventional coating" was applied over the
cover. The golf balls were incubated in a 50% relative humidity and
72.degree. F. environmental chamber and then were removed, weighed
and measured. Subsequently the balls were subjected to 100 percent
relative humidity at 72.degree. F. and then weighed and measured.
Balls with the water resistant cover were shown to have picked up
much less weight and to have incurred less size gain due to the
exposure to the high relative humidity than a control ball.
[0012] When the layer or coating of material applied to the golf
ball is an exterior coating, which will experience wear due to
mechanical contact or will experience fluid flow over the coated
surface, it is helpful to have the coating chemically bonded
directly to the substrate surface via chemical reaction of active
species which are present in the coating reactants/materials with
active species on the underlying substrate surface.
[0013] For purposes of illustrating methods of coating formation
where vaporous and liquid precursors are used to deposit a coating
on a substrate, applicants would like to mention the following
publications and patents which relate to methods of coating
formation, for purposes of illustration. Most of the background
information provided is with respect to various chlorosilane-based
precursors; however it is not intended that the present invention
be limited to this class of precursor materials.
[0014] In an article by Barry Arkles entitled "Tailoring surfaces
with silanes", published in CHEMTECH, in December of 1977, pages
766-777, the author describes the use of organo silanes to form
coatings which impart desired functional characteristics to an
underlying oxide-containing surface. In particular, the organo
silane is represented as R.sub.nSiX.sub.(4-n) where X is a
hydrolyzable group, typically halogen, alkoxy, acyloxy, or amine.
Following hydrolysis, a reactive silanol group is said to be formed
which can condense with other silanol groups, for example, those on
the surface of siliceous fillers, to form siloxane linkages. Stable
condensation products are said to be formed with other oxides in
addition to silicon oxide, such as oxides of aluminum, zirconium,
tin, titanium, and nickel. The R group is said to be a
nonhydrolyzable organic radical that may possess functionality that
imparts desired characteristics. The article also discusses
reactive tetra-substituted silanes which can be fully substituted
by hydrolyzable groups and how the silicic acid which is formed
from such substituted silanes readily forms polymers such as silica
gel, quartz, or silicates by condensation of the silanol groups or
reaction of silicate ions. Tetrachlorosilane is mentioned as being
of commercial importance since it can be hydrolyzed in the vapor
phase to form amorphous fumed silica.
[0015] The article by Dr. Arkles shows how a substrate with
hydroxyl groups on its surface can be reacted with a condensation
product of an organosilane to provide chemical bonding to the
substrate surface. The reactions are generally discussed and, with
the exception of the formation of amorphous fumed silica, the
reactions are between a liquid precursor and a substrate having
hydroxyl groups on its surface. A number of different applications
and potential applications are discussed.
[0016] In an article entitled "Organized Monolayers by Adsorption.
1. Formation and Structure of Oleophobic Mixed Monolayers on Solid
Surfaces", published in the Journal of the American Chemical
Society, Jan. 2, 1980, pp. 92-98, Jacob Sagiv discussed the
possibility of producing oleophobic monolayers containing more than
one component (mixed monolayers). The article is said to show that
homogeneous mixed monolayers containing components which are very
different in their properties and molecular shape may be easily
formed on various solid polar substrates by adsorption from organic
solutions. Irreversible adsorption is said to be achieved through
covalent bonding of active silane molecules to the surface of the
substrate.
[0017] In June of 1991, D. J. Ehrlich and J. Melngailis published
an article entitled "Fast room-temperature growth of SiO.sub.2
films by molecular-layer dosing" in Applied Physics Letters 58
(23), pp. 2675-2677. The authors describe a molecular-layer dosing
technique for room-temperature growth of .alpha.-SiO.sub.2 thin
films, which growth is based on the reaction of H.sub.2O and
SiCl.sub.4 adsorbates. The reaction is catalyzed by the hydrated
SiO.sub.2 growth surface, and requires a specific surface phase of
hydrogen-bonded water. Thicknesses of the films is said to be
controlled to molecular-layer precision; alternatively, fast
conformal growth to rates exceeding 100 nm/min is said to be
achieved by slight depression of the substrate temperature below
room temperature. Potential applications such as trench filling for
integrated circuits and hermetic ultrathin layers for multilayer
photoresists are mentioned. Excimer-laser-induced surface
modification is said to permit projection-patterned selective-area
growth on silicon.
[0018] An article entitled "Atomic Layer Growth of SiO.sub.2 on
Si(100) Using The Sequential Deposition of SiCl.sub.4 and H.sub.2O"
by Sneh et al. in Mat. Res. Soc. Symp. Proc. Vol 334, 1994, pp.
25-30, describes a study in which SiO.sub.2 thin films were said to
be deposited on Si(100) with atomic layer control at 600.degree. K.
(.apprxeq.327.degree. C.) and at pressures in the range of 1 to 50
Torr using chemical vapor deposition (CVD).
[0019] In U.S. Pat. No. 5,372,851, issued to Ogawa et al. on Dec.
13, 1995, a method of manufacturing a chemically adsorbed film is
described. In particular a chemically adsorbed film is said to be
formed on any type of substrate in a short time by chemically
adsorbing a chlorosilane based surface active-agent in a gas phase
on the surface of a substrate having active hydrogen groups. The
basic reaction by which a chlorosilane is attached to a surface
with hydroxyl groups present on the surface is basically the same
as described in other articles discussed above. In a preferred
embodiment, a chlorosilane based adsorbent or an alkoxyl-silane
based adsorbent is used as the silane-based surface adsorbent,
where the silane-based adsorbent has a reactive silyl group at one
end and a condensation reaction is initiated in the gas phase
atmosphere. A dehydrochlorination reaction or a de-alcohol reaction
is carried out as the condensation reaction. After the
dehydrochlorination reaction, the unreacted chlorosilane-based
adsorbent on the surface of the substrate is washed with a
non-aqueous solution and then the adsorbed material is reacted with
aqueous solution to form a monomolecular adsorbed film.
[0020] In an article entitled "SiO.sub.2 Chemical Vapor Deposition
at Room Temperature Using SiCl.sub.4 and H.sub.2O with an NH.sub.3
Catalyst", by J. W. Klaus and S. M. George in the Journal of the
Electrochemical Society, 147 (7) 2658-2664, 2000, the authors
describe the deposition of silicon dioxide films at room
temperature using a catalyzed chemical vapor deposition reaction.
The NH.sub.3 (ammonia) catalyst is said to lower the required
temperature for SiO.sub.2 CVD from greater than 900.degree. K. to
about 313-333.degree. K.
[0021] U.S. Patent Publication No. US 2002/0065663 A1, published on
May 30, 2002, and titled "Highly Durable Hydrophobic Coatings And
Methods", describes substrates which have a hydrophobic surface
coating comprised of the reaction products of a chlorosilyl group
containing compound and an alkylsilane. The substrate over which
the coating is applied is preferably glass. In one embodiment, a
silicon oxide anchor layer or hybrid organo-silicon oxide anchor
layer is formed from a humidified reaction product of silicon
tetrachloride or trichloromethylsilane vapors at atmospheric
pressure. Application of the oxide anchor layer is, followed by the
vapor-deposition of a chloroalkylsilane. The silicon oxide anchor
layer is said to advantageously have a root mean square surface
(RMS) roughness of less than about 6.0 nm, preferably less than
about 5.0 nm and a low haze value of less than about 3.0%. The RMS
surface roughness of the silicon oxide layer is preferably said to
be greater than about 4 nm, to improve adhesion. However, too great
an RMS surface area is said to result in large surface peaks,
widely spaced apart, which begins to diminish the desirable surface
area for subsequent reaction with the chloroalkylsilane by vapor
deposition. Too small an RMS surface is said to result in the
surface being too smooth, that is to say an insufficient increase
in the surface area/or insufficient depth of the surface peaks and
valleys on the surface.
[0022] Simultaneous vapor deposition of silicon tetrachloride and
dimethyldichlorosilane onto a glass substrate is said to result in
a hydrophobic coating comprised of cross-linked
polydimethylsiloxane which may then be capped with a
fluoroalkylsilane (to provide hydrophobicity). The substrate is
said to be glass or a silicon oxide anchor layer deposited on a
surface prior to deposition of the cross-linked
polydimethylsiloxane. The substrates are cleaned thoroughly and
rinsed prior to being placed in the reaction chamber.
[0023] U.S. Pat. No. 5,576,247 to Yano et al., issued Nov. 19,
1996, entitled: "Thin layer forming method where hydrophobic
molecular layers preventing a BPSG layer from absorbing
moisture".
[0024] Some of the various methods useful in applying layers and
coatings to a substrate have been described above. There are
numerous other patents and publications which relate to the
deposition of functional coatings on substrates, but which appear
to be more distantly related to the present invention. To provide a
monolayer or a few layers of a functional coating on a substrate
surface so that the surface will exhibit particular functional
properties it is necessary to tailor the coating precisely. Without
precise control of the deposition process, the coating may lack
thickness uniformity and surface coverage. The coating may vary in
chemical composition across the surface of the substrate, affecting
uniformity of behavior of the surface. The presence of
non-uniformities may result in functional discontinuities and
defects on the coated substrate surface which are unacceptable for
the intended application of the coated substrate.
[0025] U.S. patent application Ser. No. 10/759,857 of the present
applicants describes processing apparatus which can provide
specifically controlled, accurate delivery of precise quantities of
reactants to the process chamber, as a means of improving control
over a coating deposition process. The subject matter of the '857
application is hereby incorporated by reference in its
entirety.
[0026] The present application is related to an exterior coating
for application to a golf ball. In a first instance the exterior
coating provides a hydrophobic surface on the golf ball. In a
second instance the exterior coating provides a hydrophilic surface
on the golf ball. Use of the disclosed method of coating deposition
described below enables the precise control of process conditions
during deposition of the coatings, the coatings exhibit a uniform
functionality over the entire golf ball surface, a nanometer scale
functionality which is superior to previous golf ball coatings. Due
to the accurate delivery of quantities of reactive materials and
the conditions under which the materials can be processed, the cost
of coating application is greatly reduced as well.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 shows a cross-sectional schematic of one embodiment
of the kind of an apparatus which can be used to carry out a vapor
deposition of a coating in accordance with the method of the
present invention.
[0028] FIG. 2 is a schematic which shows the reaction mechanism
where tetrachlorosilane and water are reacted with a substrate
which exhibits active hydroxyl groups on the substrate surface, to
form a silicon oxide layer on the surface of the substrate.
[0029] FIG. 3 shows a series of water contact angles measured for
various coated surfaces. The higher the contact angle, the higher
the hydrophobicity of the coating surface.
[0030] FIG. 4A shows a three dimensional schematic of film
thickness of a silicon oxide bonding layer coating deposited on a
silicon surface as a function of the partial pressure of silicon
tetrachloride and the partial pressure of water vapor present in
the process chamber during deposition of the silicon oxide coating,
where the time period the silicon substrate was exposed to the
coating precursors was four minutes after completion of addition of
all precursor materials.
[0031] FIG. 4B shows a three dimensional schematic of film
thickness of the silicon oxide bonding layer illustrated in FIG. 4A
as a function of the water vapor partial pressure and the time
period the substrate was exposed to the coating precursors after
completion of addition of all precursor materials.
[0032] FIG. 4C shows a three dimensional schematic of film
thickness of the silicon oxide bonding layer illustrated in FIG. 4A
as a function of the silicon tetrachloride partial pressure and the
time period the substrate was exposed to the coating precursors
after completion of addition of all precursor materials.
[0033] FIG. 5A shows a three dimensional schematic of film
roughness in RMS nm of a silicon oxide bonding layer coating
deposited on a silicon surface as a function of the partial
pressure of silicon tetrachloride and the partial pressure of water
vapor present in the process chamber during deposition of the
silicon oxide coating, where the time period the silicon substrate
was exposed to the coating precursors was four minutes after
completion of addition of all precursor materials.
[0034] FIG. 5B shows a three dimensional schematic of film
roughness in RMS nm of the silicon oxide bonding layer illustrated
in FIG. 5A as a function of the water vapor partial pressure and
the time period the substrate was exposed to the coating precursors
after completion of addition of all precursor materials.
[0035] FIG. 5C shows a three dimensional schematic of film
roughness in RMS nm of the silicon oxide bonding layer illustrated
in FIG. 5A as a function of the silicon tetrachloride partial
pressure and the time period the substrate was exposed to the
coating precursors after completion of addition of all precursor
materials.
[0036] FIG. 6 illustrates the minimal thickness of oxide-based
bonding layer which is required to provide adhesion of an
organic-based layer, as a function of the initial substrate
material, when the organic-based layer is one where the end or the
organic-based layer which bonds to the oxide-based bonding layer is
a silane and where the end of the organic-based layer which does
not bond to the oxide-based bonding layer provides a hydrophobic
surface. When the oxide thickness is adequate to provide uniform
attachment of the organic-based layer, the contact angle on the
substrate surface increases to about 110 degrees or greater.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0037] We have developed improved golf ball exterior coatings which
are used to create an extremely uniform (to within about .+-.2 nm)
hydrophobic or hydrophilic exterior coating on a golf ball surface.
When the surface of the golf ball is hydrophobic, it tends to repel
water, and this reduces the condensation of moisture present in the
air onto the golf ball as the golf ball travels through the air. As
a result, the amount of drag on the golf ball is reduced,
increasing the distance of travel which can be achieved in a given
stroke. When a golf ball is rolling across grass which exhibits a
wet surface, for example dew (condensation on the surface of the
grass) is present, or there are wet spots on the grass, there is an
advantage when the golf ball has an exterior surface which is
hydrophilic. The hydrophilic surface of the golf ball wets
uniformly and the ball rolls straighter, as the forces acting on
the ball are more uniform. Putting will be better using the golf
ball with the hydrophilic surface. When the golf ball is in a sand
trap or is on a dry grass surface where some debris is present,
there is an advantage in using a golf ball with a hydrophobic
surface which will not stick to the sand or to debris present on
the grass surface. The ball tends to stay cleaner as it rolls over
the green, improving the directionality of travel of the ball
during putting, for example.
[0038] The hydrophobic or hydrophilic exterior coating is applied
to the golf ball using vapor-phase deposition in instances where
strict control over coating thickness uniformity, and/or reduced
surface roughness is desired. The coating formation method
typically employs a batch-like addition and mixing of all of the
reactants to be consumed in a given process step, whether that step
is one in a series of steps or is the sole step in a coating
formation process. In some instances, the coating formation process
may include a number of individual steps where repetitive reactive
processes are carried out in each individual step. The apparatus
used to carry out the method provides for the addition of a precise
amount of each of the reactants to be consumed in a single reaction
step of the coating formation process. The apparatus may provide
for precise addition of quantities of different combinations of
reactants during each individual step when there are a series of
different individual steps in the coating formation process.
[0039] In addition to the control over the amount of reactants
added to the process chamber, the present invention requires
precise control over the cleanliness of the substrate, the order of
reactant(s) introduction, the total pressure (which is typically
less than atmospheric pressure) in the process chamber, the partial
vapor pressure of each vaporous component present in the process
chamber, and the temperature of the substrate and chamber walls.
The control over this combination of variables determines the
deposition rate and properties of the deposited layers. By varying
these process parameters, we control the amount of the reactants
available, the density of reaction sites, and the film growth rate,
which is the result of the balance of the competitive adsorption
and desorption processes on the substrate surface, as well as any
gas phase reactions.
[0040] The coating deposition process is carried out in a vacuum
chamber where the total pressure is lower than atmospheric pressure
and the partial pressure of each vaporous component making up the
reactive mixture is specifically controlled so that formation and
attachment of molecules on a substrate surface are well controlled
processes that can take place in a predictable manner, without
starving the reaction from any of the precursors.
[0041] In some instances, where it is desired to have a
particularly uniform growth of the composition across the coating
surface, or a variable composition across the thickness of a
multi-layered coating, more than one batch of reactants may be
charged to the process chamber during formation of the coating.
[0042] The coatings formed by the method of the invention are
sufficiently controlled that the surface roughness of the coating
in terms of RMS is typically less than about 15 nm, and is
typically in the range of about 3 nm to 10 nm. However, although
the coating itself does not create significant roughness on a
surface, the roughness of a substrate surface tends to be
replicated in the coated substrate surface. Thus, the roughness on
the surface of a golf ball is likely to be in the range of the
roughness of the outer layer (typically the cover layer) of the
golf ball over which the coating is applied.
[0043] The golf ball exterior coating may be a single layer. For
example, an oxide layer is generally hydrophilic in nature, and
various functionalized organic materials exhibit a hydrophobic
chemical group at one end of the molecule which can provide a
hydrophobic surface on the golf ball. Frequently, however, the
exterior coating includes at least two layers, where the first
layer applied over the golf ball surface is an adhesion promoting
layer to ensure bonding of a second layer which presents the
hydrophilic or hydrophobic properties on the surface of the golf
ball. The adhesion promoting layer is required on polymeric
surfaces of the kind which are known in the industry for use as an
outer cover of a golf ball. Subsequently, this adhesion promoting
layer is referred to as a "bonding" layer, for general purposes of
description.
[0044] An oxide layer has been demonstrated to work well as a
bonding layer on the golf ball surface. By controlling the precise
thickness, chemical, and structural composition of an oxide layer
on a polymeric substrate, for example, we are able to tailor the
oxide layer surface characteristics and thickness to meet the
requirements for air flow over a golf ball surface. When the golf
ball exterior coating is a hydrophobic coating, a bonding layer of
oxide is applied first, followed by a layer of organic material
which comprises organic molecules which bond to the oxide layer at
one end and presents a hydrophobic composition at the other end of
the molecule. The hydrophobic surface layer applied over the
bonding layer is typically a self-aligned monolayer coating (SAM),
which is self limiting in thickness. When the golf ball exterior
coating is a hydrophilic coating, a thick oxide layer alone may be
used to provide the hydrophilic surface, as mentioned above. In the
alternative, a layer of hydrophilic organic material which
comprises organic molecules which bond to the oxide layer at one
end and present a hydrophilic composition at the other end of the
molecule may be used over the oxide surface. An example, not by way
of limitation, such an organic material is polyethylene glycol,
which is commonly referred to as PEG or as polyethylene oxide
(PEO). The precursor for formation of the hydrophilic organic
material is typically a functionalized silane containing PEO/PEG
groups, where the silane reacts with the oxide bonding layer. The
silane functionalized PEG may be used to create a monolayer, a
self-aligned monolayer, or a polymerized cross-linked layer.
Several coating layers of PEG may be applied to increase the
thickness of the PEG layer, so long as the golf balls are not
exposed to ambient contaminants between coating steps. The coverage
and functionality of the exterior coated surface on the golf ball,
whether hydrophobic or hydrophilic, can be controlled on a
nanometer scale.
[0045] With reference to chlorosilane-based coating systems of the
kind described in the Background Art section of this application,
for example, and not by way of limitation, the degree of
hydrophobicity of the substrate after deposition of an oxide
bonding layer and after deposition of an overlying silane-based
polymeric material which presents a hydrophobic surface can be
uniformly controlled over the substrate surface. By controlling a
deposited bonding layer (for example) surface coverage and
roughness in a uniform manner (as a function of oxide deposition
parameters, for example and not by way of limitation), we are able
to control the concentration of OH reactive species on the
substrate surface. This, in turn, controls the density of reaction
sites needed for subsequent deposition of a silane-based polymeric
coating which provides an exterior hydrophobic surface. Control of
the substrate surface active site density enables uniform growth
and application of high density SAMS.
[0046] Another important aspect of the present invention is the
surface preparation of the substrate prior to initiation of any
exterior coating deposition reaction on the substrate surface. For
experimental purposes, we applied exterior coatings to golf balls
having a cover layer of an ionomer, for example and not by way of
limitation. The ionomer was a sodium or zinc salt of copolymers
derived from ethylene and methacrylic acid. A golf ball surface,
typically a cover layer, may be formed from materials in addition
to ionomers. Such additional materials may comprise polystyrene,
polybutadiene, isoprene, polyurea, polyurethane, poly-para-xylene,
poly-chloro-para-xylene, poly-dichloro-para-xylene, polyvinylidene
chloride, polyvinylchloride, polyvinylchloride, polyacrylonitrile,
fluorohalocarbons, fluorinated ethylene propylene copolymer,
polytetrafluoroethylene, polyvanilidine fluoride, polyvinyl
fluoride, perfluoroalkoxy resins, polyethylene, polyethylene
terephthalate, polypropylene high density polyethylene, polyimide,
polyamide, acrylic, and combinations thereof.
[0047] The surface of the golf balls exhibiting an ionomer cover
layer was initially cleaned using isopropyl alcohol to remove any
oils or grease that might have been present on the ball surface.
Other commonly available solvents used for surface cleaning of
plastic materials similar to ionomers may be used to remove oils or
grease present on golf ball cover surfaces prior to application of
an exterior surface coating over the cover.
[0048] Subsequent to the solvent wipe with isopropyl alcohol, the
golf ball surfaces were treated with gentle, non-bombarding
oxygen-containing plasmas, to further remove organic contaminants.
The oxide layer created over a plasma-treated polymeric substrate
may comprise aluminum oxide, titanium oxide, or silicon oxide, by
way of example and not by way of limitation. When the oxide layer
is aluminum or titanium oxide, an auxiliary process chamber (to the
process chamber described herein) may be used to create this oxide
layer. When the oxide layer is a silicon oxide layer, the silicon
oxide layer may be applied in the same processing chamber in which
the subsequent deposition of a silane-functionalized external layer
is carried out. It is advantageous to carry out the oxygen plasma
surface treatment, the oxide layer deposition and the exterior
layer deposition the same processing chamber with no intermediate
exposure of the golf ball to an uncontrolled ambient. It is also
possible to use a combination of processing chambers and to shuttle
the golf balls from chamber to chamber under controlled
environmental conditions.
[0049] In one preferred embodiment, when a hydrophobic exterior
surface coating was applied to the golf balls, an oxygen plasma
treatment, oxide layer creation and SAM layer application were
typically carried out in a single vacuum processing chamber. The
pressure in the vacuum processing chamber is typically in the range
of about 0.5 torr during the oxygen plasma treatment, in the range
of about 6 Torr to 7 Torr during formation of the oxide layer, and
in the range of about 2 Torr to 6 Torr during deposition of a SAM
layer. The process chamber baseline pressure, prior to initiation
of a treatment or deposition of a coating, is in the range of about
20 mTorr. During deposition of the exterior coating layer, which
forms the exterior surface of the golf ball, controlling the total
pressure in the vacuum processing chamber, the number and kind of
vaporous components charged to the process chamber, the partial
pressure of each vaporous component, the substrate temperature, the
temperature of the process chamber walls, and the time over which
particular conditions are maintained, enables control of the
chemical reactivity and properties of the exterior surface of the
golf ball. By controlling the process parameters, both density of
film coverage over the substrate surface and structural composition
over the substrate surface are more accurately controlled. Very
smooth films, which typically range from about 0.1 nm to less than
about 5 nm, and even more typically from about 1 nm to about 3 nm
in surface RMS roughness may be applied. These smooth oxide bonding
films can be tailored in thickness, roughness,
hydrophobicity/hydrophilicity, and density, which makes them able
to bond to whatever silane-based functional organic coatings will
provide the desired behavior on the golf ball surface. For oxide
films used to provide a bonding layer, the thickness of the oxide
film typically ranges from about 50 .ANG. to about 500 .ANG..
[0050] Oxide films deposited according to the present method can be
used as bonding layers for subsequently deposited
chlorosilane-based coating systems where one end of the organic
molecule presents chlorosilane, and the other end of the organic
molecule presents a fluorine moiety. After attachment of the
chlorosilane end of the organic molecule to the substrate, the
fluorine moiety at the other end of the organic molecule provides a
hydrophobic coating surface. Further, the degree of hydrophobicity
and the uniformity of the hydrophobic surface at a given location
across the coated surface may be controlled using the oxide-based
layer which is applied over the substrate surface prior to
application of the chlorosilane-comprising organic molecule. By
controlling the oxide-based layer application, the organic-based
layer is controlled indirectly. For example, using the process
variables previously described, we are able to control the
concentration of OH reactive species on the substrate surface.
This, in turn, controls the density of reaction sites needed for
subsequent deposition of a silane-based polymeric coating. Control
of the substrate surface active site density enables uniform growth
and application of high density self-aligned monolayer coatings
(SAMS), for example.
[0051] Organic-based functional hydrophobic layer precursors other
than the silanes may be used as well. The stability of the coating
on the exterior surface of the golf ball frequently depends on the
thickness of the oxide-based bonding layer. In some instances,
better structural stability is provided by a multilayered structure
of repeated layers of oxide-based bonding layers interleaved with
organic-based layers.
[0052] In instances where it is desired to create multilayered
coatings, for example and not by way of limitation, it is advisable
to use oxygen plasma treatment prior to and between coating
deposition steps. This oxygen plasma treatment activates dangling
bonds on the substrate surface, which dangling bonds may be exposed
to a controlled partial pressure of water vapor to create a new
concentration of OH reactive sites on the substrate surface. The
coating deposition process may then be repeated, using a silane to
create an oxide bonding layer or a silane-functionalized organic
molecule to create a hydrophobic layer on the golf ball surface, by
way of example, and not by way of limitation.
[0053] The hydrophobicity of a given substrate surface may be
measured using a water droplet shape analysis method, for example.
The range in hydrophobicity of the exterior surface of the golf
ball is typically controlled to provide a water wetted contact
angle ranging from about 100.degree. to about 125.degree.. FIG. 3
shows a series of water contact angles measured for various coated
surfaces. The higher the contact angle, the higher the
hydrophobicity of the coating surface. A golf ball surface having a
hydrophilic surface is typically controlled to provide a water
wetted contact angle ranging from about 5.degree. to about
60.degree..
[0054] A computer driven process control system may be used to
provide for a series of additions of reactants to the process
chamber in which the layer or coating is being formed. This process
control system typically also controls other process variables,
such as (for example and not by way of limitation), total process
chamber pressure (typically less than atmospheric pressure),
substrate temperature, temperature of process chamber walls,
temperature of the vapor delivery manifolds, processing time for
given process steps, and other process parameters if needed.
[0055] As a preface to the more detailed description provided
below, it should be noted that, as used in this specification and
the appended claims, the singular forms "a", "an", and "the"
include plural referents, unless the context clearly dictates
otherwise.
[0056] As a basis for understanding the invention, it is important
to discuss a processing apparatus which permits precise control
over the addition of coating precursors and other vaporous
components present within the reaction/processing chamber in which
the coating is applied. The apparatus described below is not the
only apparatus in which the present invention may be practiced, it
is merely an example of one apparatus which may be used. One
skilled in the art will recognize equivalent elements in other
forms which may be substituted and still provide an acceptable
processing system.
[0057] I. An Apparatus for Vapor Deposition of Thin Coatings
[0058] FIG. 1 shows a cross-sectional schematic of an apparatus 100
for vapor deposition of thin coatings. The apparatus 100 includes a
process chamber 102 in which thin (typically 20 .ANG. to 500 .ANG.
thick) coatings are vapor deposited. A substrate 106 to be coated
rests upon a temperature controlled substrate holder 104, typically
within a recess 107 in the substrate holder 104.
[0059] Depending on the chamber design, the substrate 106 may rest
on the chamber bottom (not shown in this position in FIG. 1).
Attached to process chamber 102 is a remote plasma source 110,
connected via a valve 108. Remote plasma source 110 may be used to
provide a plasma which is used to clean and/or convert a substrate
surface to a particular chemical state prior to application of a
coating (which enables reaction of coating species and/or catalyst
with the surface, thus improving adhesion and/or formation of the
coating); or may be used to provide species helpful during
formation of the coating (not shown) or modifications of the
coating after deposition. The plasma may be generated using a
microwave, DC, or inductive RF power source, or combinations
thereof. The process chamber 102 makes use of an exhaust port 112
for the removal of reaction byproducts and is opened for
pumping/purging the chamber 102. A shut-off valve or a control
valve 114 is used to isolate the chamber or to control the amount
of vacuum applied to the exhaust port. The vacuum source is not
shown in FIG. 1.
[0060] The apparatus 100 shown in FIG. 1 is illustrative of a vapor
deposited coating which employs two precursor materials and a
catalyst. One skilled in the art will understand that one or more
precursors and from zero to multiple catalysts may be used during
vapor deposition of a coating. A catalyst storage container 116
contains catalyst 154, which may be heated using heater 118 to
provide a vapor, as necessary. It is understood that precursor and
catalyst storage container walls, and transfer lines into process
chamber 102 will be heated as necessary to maintain a precursor or
catalyst in a vaporous state, minimizing or avoiding condensation.
The same is true with respect to heating of the interior surfaces
of process chamber 102 and the surface of substrate 106 to which
the coating (not shown) is applied. A control valve 120 is present
on transfer line 119 between catalyst storage container 116 and
catalyst vapor reservoir 122, where the catalyst vapor is permitted
to accumulate until a nominal, specified pressure is measured at
pressure indicator 124. Control valve 120 is in a normally-closed
position and returns to that position once the specified pressure
is reached in catalyst vapor reservoir 122. At the time the
catalyst vapor in vapor reservoir 122 is to be released, valve 126
on transfer line 119 is opened to permit entrance of the catalyst
present in vapor reservoir 122 into process chamber 102 which is at
a lower pressure. Control valves 120 and 126 are controlled by a
programmable process control system of the kind known in the art
(which is not shown in FIG. 1).
[0061] A Precursor 1 storage container 128 contains coating
reactant Precursor 1, which may be heated using heater 130 to
provide a vapor, as necessary. As previously mentioned, Precursor 1
transfer line 129 and vapor reservoir 134 internal surfaces are
heated as necessary to maintain a Precursor 1 in a vaporous state,
minimizing and preferably avoiding condensation. A control valve
132 is present on transfer line 129 between Precursor 1 storage
container 128 and Precursor 1 vapor reservoir 134, where the
Precursor 1 vapor is permitted to accumulate until a nominal,
specified pressure is measured at pressure indicator 136. Control
valve 132 is in a normally closed position and returns to that
position once the specified pressure is reached in Precursor 1
vapor reservoir 134. At the time the Precursor 1 vapor in vapor
reservoir 134 is to be released, valve 138 on transfer line 129 is
opened to permit entrance of the Precursor 1 vapor present in vapor
reservoir 134 into process chamber 102, which is at a lower
pressure. Control valves 132 and 138 are controlled by a
programmable process control system of the kind known in the art
(which is not shown in FIG. 1).
[0062] A Precursor 2 storage container 140 contains coating
reactant Precursor 2, which may be heated using heater 142 to
provide a vapor, as necessary. As previously mentioned, Precursor 2
transfer line 141 and vapor reservoir 146 internal surfaces are
heated as necessary to maintain Precursor 2 in a vaporous state,
minimizing, and preferably avoiding condensation. A control valve
144 is present on transfer line 141 between Precursor 2 storage
container 146 and Precursor 2 vapor reservoir 146, where the
Precursor 2 vapor is permitted to accumulate until a nominal,
specified pressure is measured at pressure indicator 148. Control
valve 141 is in a normally-closed position and returns to that
position once the specified pressure is reached in Precursor 2
vapor reservoir 146. At the time the Precursor 2 vapor in vapor
reservoir 146 is to be released, valve 150 on transfer line 141 is
opened to permit entrance of the Precursor 2 vapor present in vapor
reservoir 146 into process chamber 102, which is at a lower
pressure. Control valves 144 and 150 are controlled by a
programmable process control system of the kind known in the art
(which is not shown in FIG. 1).
[0063] During formation of a coating (not shown), golf ball
surfaces 105 are supported by a substrate holder 106, which
typically is a supporting structure which contains a number of golf
balls, with pins holding the golfballs in a manner that essentially
all of the surface of the golfballs is exposed during processing.
At least one incremental addition of vapor equal to the vapor
reservoir 122 of the catalyst 154, and the vapor reservoir 134 of
the Precursor 1, or the vapor reservoir 146 of Precursor 2 may be
added to process chamber 102. The total amount of vapor added is
controlled by both the adjustable volume size of each of the
expansion chambers (typically 50 cc up to 1,000 cc) and the number
of vapor injections (doses) into the reaction chamber. Further, the
set pressure 124 for catalyst vapor reservoir 122, or the set
pressure 136 for Precursor 1 vapor reservoir 134, or the set
pressure 148 for Precursor 2 vapor reservoir 146, may be adjusted
to control the amount (partial vapor pressure) of the catalyst or
reactant added to any particular step during the coating formation
process. This ability to control precise amounts of catalyst and
vaporous precursors to be dosed (charged) to the process chamber
102 at a specified time provides not only accurate dosing of
reactants and catalysts, but repeatability in the vapor charging
sequence.
[0064] This apparatus provides a relatively inexpensive, yet
accurate method of adding vapor phase precursor reactants and
catalyst to the coating formation process, despite the fact that
many of the precursors and catalysts are typically relatively
non-volatile materials. In the past, flow controllers were used to
control the addition of various reactants; however, these flow
controllers may not be able to handle some of the precursors used
for vapor deposition of coatings, due to the low vapor pressure and
chemical nature of the precursor materials. The rate at which vapor
is generated from some of the precursors is generally too slow to
function with a flow controller in a manner which provides
availability of material in a timely manner for the vapor
deposition process.
[0065] The apparatus discussed above allows for accumulation of the
specific quantity of vapor in the vapor reservoir which can be
charged (dosed) to the reaction. In the event it is desired to make
several doses during the coating process, the apparatus can be
programmed to do so, as described above. Additionally, adding of
the reactant vapors into the reaction chamber in controlled
aliquots (as opposed to continuous flow) greatly reduces the amount
of the reactants used and the cost of the coating.
[0066] One skilled in the art of chemical processing of a number of
substrates, such as golf balls, simultaneously will recognize that
a processing system which permits heat and mass transfer uniformly
over the entire surface of substrate is important. A number of
different designs of substrate holders for golfballs are possible
which will permit coating of essentially all of the golf ball
surface. In addition, it is possible to rotate the golf ball and
repeat the treatment or coating deposition step prior to going on
to the next step in the coating process to ensure that the entire
surface of the golf ball is coated. For example, the ball may be
rotated during progress of the plasma cleaning step, during process
of the oxide layer formation, and during deposition of the
functional organic precursor material which forms a hydrophobic
surface on the exterior of the golf ball.
[0067] II. Exemplary Embodiments of the Method of the
Invention:
[0068] A method of the invention provides for vapor-phase
deposition of coatings onto a golf ball surface, where a processing
chamber of the kind, or similar to the processing chamber described
above is employed. Each coating precursor is transferred in
vaporous form to a precursor vapor reservoir in which the precursor
vapor accumulates. A nominal amount of the precursor vapor, which
is the amount required for a coating layer deposition is
accumulated in the precursor vapor reservoir. The at least one
coating precursor is charged from the precursor vapor reservoir
into the processing chamber in which the golfballs are to be
coated. In some instances at least one catalyst vapor is added to
the process chamber in addition to the at least one precursor
vapor, where the relative quantities of catalyst and precursor
vapors are based on the physical characteristics to be exhibited by
the coating. In some instances a diluent gas is added to the
process chamber in addition to the at least one precursor vapor
(and optional catalyst vapor). The diluent gas is chemically inert
and is used to increase a total desired processing pressure, while
the partial pressure amounts of coating precursors and optionally
catalyst components are varied.
[0069] The example embodiments described below are with reference
to formation of a bonding oxide layer with an overlying
silane-based polymeric layer which presents a hydrophobic
functional group on the outer surface of the golf ball. However, it
is readily apparent to one of skill in the art that the concepts
involved can be applied to additional coating compositions and
combinations which have different functionalities, to provide golf
balls having additional functional characteristics.
[0070] Due to the need to control the functionality of the coating
at dimensions as small as nanometers, the surface preparation of
the golfball substrate, typically a cover layer of the golf ball of
the kind known generally in the art, prior to application of the
coating is very important. As an initial, optional step, the golf
ball may be wiped, dipped, or sprayed (for example) with a
degreasing solvent which will not attack the surface of the golf
ball cover. As previously described, we used isopropyl alcohol for
degreasing of the ball surface. Subsequently, the golf ball surface
was treated to remove contaminants by exposure to a uniform,
non-physically-bombarding plasma which is typically created from a
plasma source gas containing oxygen. The plasma may be a remotely
generated plasma which is fed into a processing chamber in which a
substrate to be coated resides. Depending on the coating to be
applied directly over the golf ball surface, the plasma treatment
of the golf ball surface may be carried out in the chamber in which
the coating is to be applied. This has the advantage that the golf
ball surface is easily maintained in a controlled environment
between the time that the surface is treated in preparation for
coating, and the time at which the coating is applied.
Alternatively, it is possible to use a large system which includes
several processing chambers and a centralized transfer chamber
which allows transfer of golf balls from one chamber to another via
a robot handling device, where the centralized handling chamber as
well as the individual processing chambers are each under a
controlled environment. A single chamber golf ball coating device
is advantageous in size and cost. Replaceable liners can be used
inside the chamber and replaced periodically, as a means of
preventing oxide and organic polymeric build-up on the process
chamber walls.
[0071] Depending on the polymeric composition on the golf ball
cover, in some instances it is necessary not only to remove
contaminants from the surface of the golf ball, but also to
generate --OH functional groups on the surface of the golf ball
cover material (in instances where such --OH functional groups are
not already present).
[0072] When a silicon oxide layer is applied to the golfball
surface, to provide a bonding layer, the oxide layer may be created
using the well-known catalytic hydrolysis of a chlorosilane, such
as a tetrachlorosilane, in the manner previously described. A
subsequent attachment of an organo-chlorosilane, which may or may
not include a functional moiety, may be made to impart a particular
function to the finished coating. By way of example and not by way
of limitation, the hydrophobicity or hydrophilicity of the coating
surface may be altered by the functional moiety present on a
surface of an organo-chlorosilane which becomes the exterior
surface of the coating.
[0073] The oxide layer, which may be silicon oxide or another
oxide, may be formed using the method of the present invention by
vapor phase hydrolysis of the chlorosilane, with subsequent
attachment of the hydrolyzed silane to the substrate surface.
Alternatively, the hydrolysis reaction may take place directly on
the surface of the golf ball, where moisture has been made
available on the golf ball surface to allow simultaneous
hydrolyzation and attachment of the chlorosilane to the golf ball
surface. The hydrolysis in the vapor phase using relatively wide
range of partial pressure of the silicon tetrachloride precursor in
combination with a partial pressure in the range of 10 Torr or
greater of water vapor will generally result in rougher surfaces on
the order of 5 nm RMS or greater, where the thickness of the film
formed will typically be in the range of about 20 nm or greater.
Thinner films of the kind enabled by one of the embodiments of
applicants' invention typically exhibit a 1-5 nm RMS finish and are
grown by carefully balancing the vapor and surface hydrolysis
reaction components. For example, and not by way of limitation, for
a thin film of an oxide-based layer, prepared on a silicon
substrate, where the oxide-based layer exhibits a thickness ranging
from about 2 nm to about 15 nm, typically the oxide-based layer
exhibits a 1-5 nm RMS finish. We have obtained such films in an
apparatus of the kind previously described, where the partial
pressure of the silicon tetrachloride is in the range of about 0.5
to 4.0 Torr, the partial pressure of the water vapor is in the
range of about 2 to about 8 Torr, where the total process chamber
pressure ranges from about 3 Torr to about 10 Torr, where the
golfball temperature ranges from about 20.degree. C. to about
60.degree. C., where the process chamber walls are at a temperature
ranging from about 30.degree. C. to about 60.degree. C., and where
the time period over which the golf ball is exposed to the
combination of silicon tetrachloride and water vapor ranges from
about 2 minutes to about 12 minutes. This deposition process will
be described in more detail subsequently herein, with reference to
FIGS. 6A through 6C.
[0074] A multilayered coating process may include plasma treatment
of the surface of one deposited layer prior to application of an
overlying layer. Typically, the plasma used for such treatment is a
low density plasma. This plasma may be a remotely generated plasma.
The most important feature of the treatment plasma is that it is a
"soft" plasma which affects the exposed surface enough to activate
the surface of the layer being treated, but not enough to etch
through the layer. The apparatus used to carry out the method
provides for the addition of a precise amount of each of the
reactants to be consumed in a single reaction step of the coating
formation process. The apparatus may provide for precise addition
of different combinations of reactants during each individual step
when there are a series of different individual steps in the
coating formation process. Some of the individual steps may be
repetitive.
[0075] One example of the application of the method described here
is deposition of a multilayered coating including at least one
oxide-based layer. The thickness of the oxide-based layer depends
on the end-use application for the multilayered coating. The
oxide-based layer (or a series of oxide-based layers alternated
with organic-based layers) may be used to increase the overall
thickness of the multilayered coating (which typically derives the
majority of its thickness from the oxide-based layer), and
depending on the mechanical properties to be obtained, the
oxide-based layer content of the multilayered coating may be
increased when more coating rigidity and abrasion resistance is
required.
[0076] The oxide-based layer is frequently used to provide a
bonding surface for subsequently deposited various molecular
organic-based coating layers. When the surface of the oxide-based
layer is one containing --OH functional groups, the organic-based
coating layer typically includes, for example and not by way of
limitation, a silane-based functionality which permits covalent
bonding of the organic-based coating layer to --OH functional
groups present on the surface of the oxide-based layer. When the
surface of the oxide-based layer is one capped with halogen
functional groups, such as chlorine, by way of example and not by
way of limitation, the organic-based coating layer includes, for
example, an --OH functional group, which permits covalent bonding
of the organic-based coating layer to the oxide-based layer
functional halogen group.
[0077] By controlling the precise thickness, chemical, and
structural composition of an oxide-based layer on a golf ball, for
example, we are able to direct the coverage and the functionality
of a coating applied over the bonding oxide layer. The coverage and
functionality of the coating can be controlled over the entire golf
ball surface on a nm scale. Specific, different thicknesses of an
oxide-based golf ball bonding layer are required on different golf
balls covering layers. Some golf ball cover layers require an
alternating series of oxide-based/organic-based layers to provide
surface stability for a coating structure.
[0078] With respect to golf ball surface properties, such as
hydrophobicity or hydrophilicity, for example, a silicon surface
becomes hydrophilic, to provide a 5 degree water contact angle (or
less), after plasma treatment when there is some moisture present.
Not much moisture is required, for example, typically the amount of
moisture present after pumping a chamber from ambient air down to
about 15 mTorr to 20 mTorr is sufficient moisture. Glass and
polystyrene materials become hydrophilic, to a 5 degree water
contact angle, after the application of about 80 .ANG. or more of
an oxide-based layer. An acrylic surface requires about 150 .ANG.
or more of an oxide-based layer to provide a 5 degree water contact
angle.
[0079] There is also a required thickness of oxide-based layer to
provide a good bonding surface for reaction with a subsequently
applied organic-based layer. By a good bonding surface, it is meant
a surface which provides full, uniform surface coverage of the
organic-based layer. By way of example, about 80 .ANG. or more of a
oxide-based bonding layer over a silicon substrate provides a
uniform hydrophobic contact angle, about 112 degrees, upon
application of a SAM organic-based layer deposited from an FDTS
(perfluorodecyltrichlorosilanes) precursor. About 150 .ANG. or more
of oxide-based substrate bonding layer is required over a glass
substrate or a polystyrene substrate to obtain a uniform coating
having a similar contact angle. About 400 .ANG. or more of
oxide-based substrate bonding layer is required over an acrylic
substrate to obtain a uniform coating having a similar contact
angle.
[0080] The organic-based layer precursor, in addition to containing
a functional group capable of reacting with the oxide-based layer
to provide a covalent bond, may also contain a functional group at
a location which will form the exterior surface of the attached
organic-based layer. This functional group may subsequently be
reacted with other organic-based precursors, or may be the final
layer of the coating and be used to provide surface properties of
the coating, such as to render the surface hydrophobic or
hydrophilic, by way of example and not by way of limitation. The
functionality of an attached organic-based layer may be affected by
the chemical composition of the previous organic-based layer (or
the chemical composition of the initial substrate) if the thickness
of the oxide layer separating the attached organic-based layer from
the previous organic-based layer (or other substrate) is
inadequate. The required oxide-based layer thickness is a function
of the chemical composition of the substrate surface underlying the
oxide-based layer, as illustrated above. In some instances, to
provide structural stability for the surface layer of the coating,
it is necessary to apply several alternating layers of an
oxide-based layer and an organic-based layer.
[0081] With reference to chlorosilane-based coating systems of the
kind described in the Background Art section of this application,
where one end of the organic molecule presents chlorosilane, and
the other end of the organic molecule presents a fluorine moiety,
after attachment of the chlorosilane end of the organic molecule to
the substrate, the fluorine moiety at the other end of the organic
molecule provides a hydrophobic coating surface. Further, the
degree of hydrophobicity and the uniformity of the hydrophobic
surface at a given location across the coated surface may be
controlled using the oxide-based layer which is applied over the
substrate surface prior to application of the
chlorosilane-comprising organic molecule. By controlling the
oxide-based layer application, the organic-based layer is
controlled indirectly. For example, using the process variables
previously described, we are able to control the concentration of
OH reactive species on the substrate surface. This, in turn,
controls the density of reaction sites needed for subsequent
deposition of a silane-based polymeric coating. Control of the
substrate surface active site density enables uniform growth and
application of high density self-aligned monolayer coatings (SAMS),
for example.
[0082] We have discovered that it is possible to convert a
hydrophilic-like substrate surface to a hydrophobic surface by
application of an oxide-based layer of the minimal thickness
described above with respect to a given substrate, followed by
application of an organic-based layer over the oxide-based layer,
where the organic-based layer provides hydrophobic surface
functional groups on the end of the organic molecule which does not
react with the oxide-based layer. However, when the initial
substrate surface is a hydrophobic surface and it is desired to
convert this surface to a hydrophilic surface, it is necessary to
use a structure which comprises more than one oxide-based layer to
obtain stability of the applied hydrophilic surface in water. It is
not always just the thickness of the oxide-based layer or the
thickness of the organic-based layer which is controlling. The
structural stability provided by a multilayered structure of
repeated layers of oxide-based material interleaved with
organic-based layers provides excellent results.
[0083] After deposition of a first organic-based layer, and prior
to the deposition of a subsequent layer in a multilayered coating,
it is advisable to use an in-situ oxygen plasma treatment. This
treatment activates reaction sites of the first organic-based layer
and may be used as part of a process for generating an oxide-based
layer or simply to activate dangling bonds on the substrate
surface. The activated dangling bonds may be exploited to provide
reactive sites on the substrate surface. For example, an oxygen
plasma treatment in combination with a controlled partial pressure
of water vapor may be used to create a new concentration of OH
reactive species on an exposed surface. The activated surface is
then used to provide covalent bonding with the next layer of
material applied. A deposition process may then be repeated,
increasing the total coating thickness, and eventually providing a
surface layer having the desired surface properties. In some
instances, where the substrate surface includes metal atoms,
treatment with the oxygen plasma and moisture provides a metal
oxide-based layer containing --OH functional groups. This
oxide-based layer is useful for increasing the overall thickness of
the multilayered coating and for improving mechanical strength and
rigidity of the multilayered coating.
EXAMPLE ONE
[0084] Deposition of a Silicon Oxide Layer Having a Controlled
Number of OH Reactive Sites Available on the Oxide Layer
Surface
[0085] FIG. 2 shows a schematic 200 of the mechanism of bonding
oxide layer formation. In particular, a substrate 202,
plasma-cleaned golf ball layer surface, for example, may have some
OH groups 204 present on the surface 203. A chlorosilane 208, such
as the tetrachlorosilane shown, and water 206 are reacted with the
OH groups 204, either simultaneously or in sequence, to produce the
oxide layer 205 shown on surface 203 of substrate 202 and byproduct
HCl 210. In addition to chlorosilane precursors, chlorosiloxanes,
fluorosilanes, and fluorosiloxanes may be used to provide the oxide
bonding layer.
[0086] Subsequently, the surface of the oxide layer 205 can be
further reacted with water 216 to replace C1 atoms on the upper
surface of oxide layer 205 with OH groups 217, to produce the
hydroxylated layer 215 shown on surface 203 of substrate 202 and
byproduct HCl 220. By controlling the amount of water used in both
reactions, the frequency of OH reactive sites available on the
oxide surface is controlled. The process may be repeated any number
of times to produce an oxide bonding layer of the desired
thickness.
EXAMPLE TWO
[0087] To evaluate process parameters useful in preparation of a
silicon oxide bonding layer, silicon oxide layers were applied over
a glass substrate. The glass substrate was treated with an oxygen
plasma in the presence of residual moisture which was present in
the process chamber (after pump down of the chamber to about 20
mTorr) to provide a clean surface (free from organic contaminants)
and to provide the initial OH groups on the glass surface.
[0088] Various process conditions for the subsequent reaction of
the OH groups on the glass surface with vaporous tetrachlorosilane
and water are provided below in Table I, along with data related to
the thickness and roughness of the oxide coating obtained and the
contact angle (indicating hydrophobicity/hydrophilicity) obtained
under the respective process conditions. A lower contact angle
indicates increased hydrophilicity and an increase in the number of
available OH groups on the silicon oxide surface. TABLE-US-00001
TABLE I Deposition of a Silicon Oxide Layer of Varying
Hydrophilicity Partial Partial Pressure Pressure SiO.sub.2 Order
SiCl.sub.4 H.sub.2O Reaction Coating Coating Contact Run of Vapor
Vapor Time Thickness Roughness Angle*** No. Dosing (Torr) (Torr)
(min.) (nm) (RMS, nm)* (.degree.) 1 First.sup.2 0.8 4.0 10 3 1
<5 SiCl.sub.4 2 First.sup.1 4.0 10.0 10 35 5 <5 H.sub.2O 3
First.sup.2 4.0 10.0 10 30 4 <5 SiCl.sub.4 Partial Partial FOTS
Pressure Pressure Surface Order FOTS H.sub.2O Reaction Coating
Coating Contact of Vapor Vapor Time Thickness Roughness Angle***
Dosing (Torr) (Torr) (min.) (nm)** (RMS, nm)* (.degree.) 1
First.sup.3 0.2 0.8 15 4 1 108 FOTS 2 First.sup.3 0.2 0.8 15 36 5
109 FOTS 3 First.sup.3 0.2 0.8 15 31 4 109 FOTS *Coating roughness
is the RMS roughness measured by AFM (atomic force microscopy).
**The FOTS coating layer was a monolayer which added .apprxeq.1 nm
in thickness. ***Contact angles were measured with 18 M.OMEGA. D.I.
water. .sup.1The H.sub.2O was added to the process chamber 10
seconds before the SiCl.sub.4 was added to the process chamber.
.sup.2The SiCl.sub.4 was added to the process chamber 10 seconds
before the H.sub.2O was added to the process chamber. .sup.3The
FOTS was added to the process chamber 5 seconds before the H.sub.2O
was added to the process chamber. .sup.4The substrate temperature
and the chamber wall temperature were each 35.degree. C. for both
application of the SiO.sub.2 bonding/bonding layer and for
application of the FOTS organosilane overlying monolayer (SAM)
layer.
[0089] We learned that very different film thicknesses and film
surface roughness characteristics can be obtained as a function of
the partial pressures of the precursors, despite the maintenance of
the same time period of exposure to the precursors. Table II below
illustrates this unexpected result. TABLE-US-00002 TABLE II
Response Surface Design* Silicon Oxide Layer Deposition Partial
Partial Substrate Coating Pressure Pressure and Surface Total
SiCl.sub.4 H.sub.2O Chamber Reaction Coating Roughness Run Pressure
Vapor Vapor Wall Temp. Time Thickness RMS No. (Torr) (Torr) (Torr)
(.degree. C.) (min.) (nm) (nm) 1 9.4 2.4 7 35 7 8.8 NA 2 4.8 0.8 4
35 7 2.4 1.29 3 6.4 2.4 4 35 4 3.8 1.39 4 14.0 4.0 10 35 7 21.9 NA
5 7.8 0.8 7 35 4 4.0 2.26 6 11.0 4.0 7 35 10 9.7 NA 7 11.0 4.0 7 35
4 10.5 NA 8 12.4 2.4 10 35 4 14.0 NA 9 6.4 2.4 4 35 10 4.4 1.39 10
9.4 2.4 7 35 7 8.7 NA 11 12.4 2.4 10 35 10 18.7 NA 12 9.4 2.4 7 35
7 9.5 NA 13 8.0 4.8 4 35 7 6.2 2.16 14 10.8 0.8 10 35 7 6.9 NA 15
7.8 0.8 7 35 10 4.4 2.24 *(Box-Behnken) 3 Factors, 3 Center Points
NA = Not Available, Not Measured
[0090] In addition to the tetrachlorosilane described above as a
precursor for oxide formation, other chlorosilane precursors such a
trichlorosilanes, dichlorosilanes work well as a precursor for
oxide formation. Examples of specific advantageous precursors
include hexachlorodisilane (Si.sub.2Cl.sub.6) and
hexachlorodisiloxane (Si.sub.2Cl.sub.6O). As previously mentioned,
in addition to chlorosilanes, chlorosiloxanes, fluorosilanes, and
fluorosiloxanes may also be used as precursors.
[0091] Similarly, the vapor deposited silicon oxide coating from
the SiCl.sub.4 and H.sub.2O precursors was applied over glass,
polycarbonate, acrylic, polyethylene and other plastic materials
using the same process conditions as those described above. Prior
to application of the silicon oxide coating, the surface to be
coated was treated with an oxygen plasma.
EXAMPLE THREE
[0092] In the preferred embodiment discussed in detail below, the
silicon oxide bonding layer was applied over golf ball having a
polymeric cover layer of ionomer, which exhibited a contact angle
coming out of the box which ranged between about 80.degree. and
about 90.degree.. The golf ball was wiped with isopropyl alcohol to
remove any grease or oils present on the golf ball surface. The
golf ball surface was then treated with an oxygen plasma in the
presence of residual moisture which was present in the process
chamber (after pump down of the chamber to about 20 mTorr) to
provide a clean surface (free from organic contaminants) and to
provide the initial OH groups on the golf ball surface. In a
process chamber of the kind described above, the flow rate of
oxygen was about 400 sccm, and the RF power applied to create the
plasma was about 200 W, with the exposure time of the golf ball
being about 5 minutes at 35.degree. C.
[0093] A silicon oxide coating of the kind described above was
applied over the golf ball surfaces by treatment with a combination
of silicon tetrachloride and water vapor in the manner described
above. This produced a hydrophilic surface on the golf balls. In
one embodiment the amount of silicon tetrachloride (SiCl.sub.4)
charged to the reactor was 1 each 300 cc volumetric charge at 18
Torr, which was used in combination with 4 each 300 cc volumetric
charges at 18 Torr of water (H.sub.2O). The pressure in the process
chamber with all reagents added was about 7 Torr, the temperature
in the process chamber was about 35.degree. C., and the deposition
time period (reaction time) was about 10 minutes. This produced an
oxide coating having a thickness of about 120 .ANG. to about 150
.ANG.. This oxide thickness is acceptable for use as a bonding
oxide layer.
[0094] When the oxide layer is to be used as a single layer to
provide a hydrophilic surface on the golf ball, a thicker coating
is preferred. A coating having a thickness ranging from about 200
.ANG. to about 2,000 .ANG. may be used. The thicker coating may be
generated using the process described above, where the deposition
step is repeated a number of times. The length of the repeated step
commonly ranges from about 2 minutes to about 10 minutes, depending
on the overall thickness of the oxide layer which is to be
obtained.
[0095] When the oxide layer is to act as a bonding layer,
subsequent to deposition of the oxide layer, a functionalized
organic layer is applied over the surface of the oxide layer to
create a specialized hydrophilic or a hydrophobic surface.
[0096] When the exterior surface on the golf ball is to be a
specialized hydrophilic surface, a functionalized organic material
such as a silane functionalized PEO or PEG layer may be deposited
over the oxide bonding layer. The functionalized silane precursor
vapor containing PEO/PEG groups may be reacted with the hydrophilic
silicon oxide layer to form a layer selected from the group
consisting of a monolayer, a self-aligned mono-layer, and a
polymerized cross-linked layer. Although just one layer of PEO/PEG
may be applied, when it is desired to increase the thickness of the
PEO/PEG layer, the deposition step may be repeated a number of
times. For example, to apply an mPEG layer, mPEG
(methoxy(polyethyleneoxy) propyltrimethoxysilane, Gelest P/N SIM
6492.7, MW=450-620 was used, or to apply a PEG layer,
(polyethyleneoxy) propyltrichlorosilane, Gelest P/N SIM 6492.66,
MW=450-620) was charged to the process chamber from a vapor
reservoir of 300 cc, where the mPEG or PEG vapor pressure in the
vapor reservoir was about 0.5 Torr. (Combinations of mPEG with PEG
may also be used.) Four chamber volumes of mPEG or PEG were
charged, creating a partial pressure of about 250 mTorr in the
coating process chamber. The substrate was exposed to mPEG vapor or
to the PEG vapor each time for a time period of 15 minutes. The
substrate temperature and the temperature of the process chamber
walls was about 350.degree. C. The MPEG coating or PEG coating
thickness obtained was about 20 .ANG..
[0097] When the exterior surface on the golf ball is to be a
hydrophobic surface, a self aligned monolayer (SAM) coating formed
from an organic precursor, for example and not by way of limitation
from fluoro-tetrahydrooctyldimethylchlorosilane (FOTS), or from
perfluorodecyltrichlorosilane (FDTS) may be applied over an oxide
bonding layer. A FDTS hydrophobic exterior surface layer may be
applied using 4 each 300 cc volumes at 0.5 Torr of FDTS and 1 each
300 cc volume at 18 Torr of H.sub.2O. The overall pressure in the
process chamber after addition of all reactants was about 5 Torr,
the temperature in the process chamber was about 35.degree. C., and
the deposition time period (reaction time) was about 15 minutes.
This produced a FDTS coating thickness of about 15 .ANG..
[0098] Functional properties designed to meet a particular
functionality for the golf ball can be tailored by either
sequentially adding an organo-silane precursor to the oxide coating
precursors or by using an organo-silane precursor(s) for formation
of the last, top layer coating. Organo-silane precursor materials
may include functional groups such that the silane precursor
includes an alkyl group, an alkoxyl group, an alkyl substituted
group containing fluorine, an alkoxyl substituted group containing
fluorine, a vinyl group, an ethynyl group, or a substituted group
containing a silicon atom or an oxygen atom, by way of example and
not by way of limitation. In particular, organic-containing
precursor materials such as (and not by way of limitation) silanes,
chlorosilanes, fluorosilanes, methoxy silanes, alkyl silanes, amino
silanes, epoxy silanes, glycoxy silanes, and acrylosilanes are
useful in general.
[0099] Some of the particular precursors used to produce coatings
are, by way of example and not by way of limitation,
perfluorodecyltrichlorosilanes (FDTS), undecenyltrichlorosilanes
(UTS), vinyl-trichlorosilanes (VTS), decyltrichlorosilanes (DTS),
octadecyltrichlorosilanes (OTS), dimethyldichlorosilanes (DDMS),
dodecenyltricholrosilanes (DDTS),
fluoro-tetrahydrooctyldimethylchlorosilanes (FOTS),
perfluorooctyldimethylchlorosilanes, aminopropylmethoxysilanes
(APTMS), fluoropropylmethyldichlorosilanes, and
perfluorodecyldimethylchlorosilanes. The OTS, DTS, UTS, VTS, DDTS,
FOTS, and FDTS are all trichlorosilane precursors. The other end of
the precursor chain is a saturated hydrocarbon with respect to OTS,
DTS, and UTS; contains a vinyl functional group, with respect to
VTS and DDTS; and contains fluorine atoms with respect to FDTS
(which also has fluorine atoms along the majority of the chain
length). Other useful precursors include
3-aminopropyltrimethoxysilane (APTMS), which provides amino
functionality, and 3-glycidoxypropyltrimethoxysilane (GPTMS). One
skilled in the art of organic chemistry can see that the vapor
deposited coatings from these precursors can be tailored to provide
particular functional characteristics for a coated surface. The use
of precursors which provide a fluorine-containing surface as the
exterior surface of the golf ball provide excellent hydrophobic
properties. These precursors are favored in the present golf ball
applications.
[0100] Most of the silane-based precursors, such as commonly used
di- and tri-chlorosilanes, for example and not by way of
limitation, tend to create agglomerates on the surface of the
substrate during the coating formation. These agglomerates can
cause structure malfunctioning or stiction. Such agglomerations are
produced by partial hydrolysis and polycondensation of the
polychlorosilanes. This agglomeration can be prevented by precise
metering of moisture in the process ambient which is a source of
the hydrolysis, and by carefully controlled metering of the
availability of the chlorosilane precursors to the coating
formation process. The carefully metered amounts of material and
careful temperature control of the substrate and the process
chamber walls can provide the partial vapor pressure and
condensation surfaces necessary to control formation of the coating
on the surface of the substrate rather than promoting undesired
reactions in the vapor phase or on the process chamber walls.
EXAMPLE FOUR
[0101] When the oxide-forming silane and the organo-silane which
includes the functional moiety are deposited simultaneously
(co-deposited), the reaction may be so rapid that the sequence of
precursor addition to the process chamber becomes critical. For
example, in a co-deposition process of SiCl.sub.4/FOTS/H.sub.2O, if
the FOTS is introduced first, it deposits on the glass substrate
surface very rapidly in the form of islands, preventing the
deposition of a homogeneous composite film. Examples of this are
provided in Table III, below.
[0102] When the oxide-forming silane is applied to the substrate
surface first, to form the oxide layer with a controlled density of
potential OH reactive sites available on the surface, the
subsequent reaction of the oxide surface with a FOTS precursor
provides a uniform film without the presence of agglomerated
islands of polymeric material, examples of this are provided in
Table III below. TABLE-US-00003 TABLE III Deposition of a Coating
Upon a Silicon Substrate* Using Silicon tetrachloride and FOTS
Precursors Substrate Partial Partial Partial and Total Pressure
Pressure Pressure Chamber Pres- SiCl.sub.4 FOTS H.sub.2O Wall Run
sure Vapor Vapor Vapor Temp. No. (Torr) (Torr) (Torr) (Torr)
(.degree. C.) 1 FOTS + H.sub.2O 1 -- 0.2 0.8 35 2 H.sub.2O +
SiCl.sub.4 141 4 -- 100.8 35 followed by -- 0.20 FOTS + H.sub.2O 3
FOTS + 14.2 4 0.2 10 35 SiCl.sub.4 + H.sub.2O 4 SiCl.sub.4 +
H.sub.2O 14 4 -- 10 35 5 SiCl.sub.4 + H.sub.2O 5.8 0.8 -- 5 35 6
SiCl.sub.4 + H.sub.2O 14 4 -- 10 35 repeated twice Coating Reaction
Coating Roughness Contact Time Thickness (nm)** Angle*** (min.)
(nm) RMS (.degree.) 1 15 0.7 0.1 110 2 10 + 15 35.5 4.8 110 3 15
1.5 0.8 110 4 10 30 0.9 <5 5 10 4 0.8 <5 6 10 + 10 55 1 <5
*The silicon substrates used to prepare experimental samples
described herein exhibited an initial surface RMS roughness in the
range of about 0.1 nm, as measured by Atomic Force Microscope
(AFM). **Coating roughness is the RMS roughness measured by AFM.
***Contact angles were measured with 18 M.OMEGA. D.I. water.
[0103] An example process description for Run No. 2 was as
follows.
[0104] Step 1. Pump down the reactor and purge out the residual air
and moisture to a final baseline pressure of about 30 mTorr or
less.
[0105] Step 2. Perform O.sub.2 plasma clean of the substrate
surface to eliminate residual surface contamination and to
oxygenate/hydroxylate the substrate. The cleaning plasma is an
oxygen-containing plasma. Typically the plasma source is a remote
plasma source, which may employ an inductive power source. However,
other plasma generation apparatus may be used. In any case, the
plasma treatment of the substrate is typically carried out in the
coating application process chamber. The plasma density/efficiency
should be adequate to provide a substrate surface after plasma
treatment which exhibits a contact angle of about 10.degree. or
less when measured with 18 M.OMEGA. D.I. water. The coating chamber
pressure during plasma treatment of the substrate surface in the
coating chamber was 0.5 Torr, and the duration of substrate
exposure to the plasma was 5 minutes.
[0106] Step 3. Inject SiCl.sub.4 and within 10 seconds inject water
vapor at a specific partial pressure ratio to the SiCl.sub.4, to
form a silicon oxide base layer on the substrate. For example, for
the glass substrate discussed in Table III, 1 volume (300 cc at 100
Torr) of SiCl.sub.4 to a partial pressure of 4 Torr was injected,
then, within 10 seconds 10 volumes (300 cc at 17 Torr each) of
water vapor were injected to produce a partial pressure of 10 Torr
in the process chamber, so that the volumetric pressure ratio of
water vapor to silicon tetrachloride is about 2.5. The substrate
was exposed to this gas mixture for 1 min to 15 minutes, typically
for about 10 minutes. The substrate temperature in the examples
described above was in the range of about 35.degree. C. Substrate
temperature may be in the range from about 20.degree. C. to about
80.degree. C. The process chamber surfaces were also in the range
of about 35.degree. C.
[0107] Step 4. Evacuate the reactor to <30 mTorr to remove the
reactants.
[0108] Step 5. Introduce the chlorosilane precursor and water vapor
to form a hydrophobic coating. In the example in Table III, FOTS
vapor was injected first to the charging reservoir, and then into
the coating process chamber, to provide a FOTS partial pressure of
200 mTorr in the process chamber, then, within 10 seconds, H.sub.2O
vapor (300 cc at 12 Torr) was injected to provide a partial
pressure of about 800 mTorr, so that the total reaction pressure in
the chamber was 1 Torr. The substrate was exposed to this mixture
for 5 to 30 minutes, typically 15 minutes, where the substrate
temperature was about 35.degree. C. Again, the process chamber
surface was also at about 35.degree. C.
[0109] An example process description for Run No. 3 was as
follows.
[0110] Step 1. Pump down the reactor and purge out the residual air
and moisture to a final baseline pressure of about 30 mTorr or
less.
[0111] Step 2. Perform remote O.sub.2 plasma clean to eliminate
residual surface contamination and to oxygenate/hydroxylate the
glass substrate. Process conditions for the plasma treatment were
the same as described above with reference to Run No. 2.
[0112] Step 3. Inject FOTS into the coating process chamber to
produce a 200 mTorr partial pressure in the process chamber. Then,
inject 1 volume (300 cc at 100 Torr) of SiCl.sub.4 from a vapor
reservoir into the coating process chamber, to a partial pressure
of 4 Torr in the process chamber. Then, within 10 seconds, inject
ten volumes (300 cc at 17 Torr each) of water vapor from a vapor
reservoir into the coating process chamber, to a partial pressure
of 10 Torr in the coating process chamber. Total pressure in the
process chamber is then about 14 Torr. The substrate temperature
was in the range of about 35.degree. C. for the specific examples
described, but could range from about 15.degree. C. to about
80.degree. C. The substrate was exposed to this three gas mixture
for about 1-15 minutes, typically about 10 minutes.
[0113] Step 4. Evacuate the process chamber to a pressure of about
30 mTorr to remove excess reactants.
EXAMPLE FIVE
[0114] FIG. 5 illustrates contact angles for a series of surfaces
exposed to water, where the surfaces exhibited different
hydrophobicity, with an increase in contact angle representing
increased hydrophobicity. This data is provided as an illustration
to make the contact angle data presented in tables herein more
meaningful.
EXAMPLE SIX
[0115] FIG. 4A shows a three dimensional schematic 400 of film
thickness of a silicon oxide bonding layer coating deposited on a
silicon surface as a function of the partial pressure of silicon
tetrachloride and the partial pressure of water vapor present in
the process chamber during deposition of the silicon oxide coating,
where the temperature of the substrate and of the coating process
chamber walls was about 35.degree. C., and the time period the
silicon substrate was exposed to the coating precursors was four
minutes after completion of addition of all precursor materials.
The precursor SiCl.sub.4 vapor was added to the process chamber
first, with the precursor H.sub.2O vapor added within 10 seconds
thereafter. The partial pressure of the H.sub.2O in the coating
process chamber is shown on axis 402, with the partial pressure of
the SiCl.sub.4 shown on axis 404. The film thickness is shown on
axis 406 in Angstroms. The film deposition time after addition of
the precursors was 4 minutes. The thinner coatings exhibited a
smoother surface, with the RMS roughness of a coating at point 408
on Graph 400 being in the range of 1 nm (10 .ANG.). The thicker
coatings exhibited a rougher surface, which was still smooth
relative to coatings generally known in the art. At point 410 on
Graph 400, the RMS roughness of the coating was in the range of 4
nm (40 .ANG.). FIG. 5A shows a three dimensional schematic 500 of
the film roughness in RMS, nm which corresponds with the coated
substrate for which the coating thickness is illustrated in FIG.
4A. The partial pressure of the H.sub.2O in the coating process
chamber is shown on axis 502, with the partial pressure of the
SiCl.sub.4 shown on axis 504. The film roughness in RMS, nm is
shown on axis 506. The film deposition time after addition of all
of the precursors was 7 minutes. As previously mentioned, the
thinner coatings exhibited a smoother surface, with the RMS
roughness of a coating at point 508 being in the range of 1 nm (10
.ANG.) and the roughness at point 510 being in the range of 4 nm
(40 .ANG.).
[0116] FIG. 4B shows a three dimensional schematic 420 of film
thickness of the silicon oxide bonding layer illustrated in FIG. 4A
as a function of the water vapor partial pressure and the time
period the substrate was exposed to the coating precursors after
completion of addition of all precursor materials. The time period
of exposure of the substrate is shown on axis 422 in minutes, with
the H.sub.2O partial pressure shown on axis 424 in Torr, and the
oxide coating thickness shown on axis 426 in Angstroms. The partial
pressure of SiCl.sub.4 in the silicon oxide coating deposition
chamber was 0.8 Torr.
[0117] FIG. 4C shows a three dimensional schematic 440 of film
thickness of the silicon oxide bonding layer illustrated in FIG. 4A
as a function of the silicon tetrachloride partial pressure and the
time period the substrate was exposed to the coating precursors
after completion of addition of all precursor materials. The time
period of exposure is shown on axis 442 in minutes, with the
SiCl.sub.4 partial pressure shown on axis 446 in Torr, and the
oxide thickness shown on axis 446 in Angstroms. The H.sub.2O
partial pressure in the silicon oxide coating deposition chamber
was 4 Torr.
[0118] A comparison of FIGS. 4A-4C makes it clear that it is the
partial pressure of the H.sub.2O which must be more carefully
controlled in order to ensure that the desired coating thickness is
obtained.
[0119] FIG. 5B shows a three dimensional schematic 520 of film
roughness of the silicon oxide bonding layer illustrated in FIG. 4B
as a function of the water vapor partial pressure and the time
period the substrate was exposed to the coating precursors after
completion of addition of all precursor materials. The time period
of exposure of the substrate is shown on axis 522 in minutes, with
the H.sub.2O partial pressure shown on axis 524 in Torr, and the
surface roughness of the silicon oxide layer shown on axis 526 in
RMS, nm. The partial pressure of the SiCl.sub.4 in the silicon
oxide coating deposition chamber was 2.4 Torr.
[0120] FIG. 5C shows a three dimensional schematic 540 of film
roughness thickness of the silicon oxide bonding layer illustrated
in FIG. 4A as a function of the silicon tetrachloride partial
pressure and the time period the substrate was exposed to the
coating precursors after completion of addition of all precursor
materials. The time period of exposure is shown on axis 542 in
minutes, with the SiCl.sub.4 partial pressure shown on axis 544 in
Torr, and the surface roughness of the silicon oxide layer shown on
axis 546 in RMS, nm. The partial pressure of the H.sub.2O in the
silicon oxide coating deposition chamber was 7.0 Torr.
[0121] A comparison of FIGS. 5A-5C makes it clear that it is the
partial pressure of the H.sub.2O which must be more carefully
controlled in order to ensure that the desired roughness of the
coating surface is obtained.
[0122] FIG. 6 shows a graph 600, which illustrates the relationship
between the hydrophobicity obtained on the surface of a SAM layer
deposited from perfluorodecyltrichlorosilane (FDTS), as a function
of the thickness of an oxide-based layer over which the FDTS layer
was deposited. The oxide layer was deposited in the manner
described above, using tetrachlorosilane precursor, with sufficient
moisture that a silicon oxide surface having sufficient hydroxyl
groups present to provide a surface contact angle (with a DI water
droplet) of 5 degrees was produced.
[0123] The oxide-based layer and the organic-based layer generated
from an FDTS precursor were deposited as follows: The process
chamber was vented and the substrate was loaded into the chamber.
Prior to deposition of the oxide-based layer, the surface of the
substrate was plasma cleaned to eliminate residual surface
contamination and to oxygenate/hydroxylate the substrate. The
chamber was pumped down to a pressure in the range of about 30
mTorr or less. The substrate surface was then plasma treated using
a low density, non-physically-bombarding plasma which was created
externally from a plasma source gas containing oxygen. The plasma
was created in an external chamber which is a high efficiency
inductively coupled plasma generator, and was fed into the
substrate processing chamber. The plasma treatment was in the
manner previously described herein, where the processing chamber
pressure during plasma treatment was in the range of about 0.5
Torr, the temperature in the processing chamber was about
35.degree. C., and the duration of substrate exposure to the plasma
was about 5 minutes.
[0124] After plasma treatment, the processing chamber was pumped
down to a pressure in the range of about 30 mTorr or less to
evacuate remaining oxygen species. Optionally, processing chamber
may be purged with nitrogen up to a pressure of about 10 Torr to
about 20 Torr and then pumped down to the pressure in the range of
about 30 mTorr. An adhering oxide-based layer was then deposited on
the substrate surface. The thickness of the oxide-based layer
depended on the substrate material, as previously discussed.
SiCl.sub.4 vapor was injected into the process chamber at a partial
pressure to provide a desired nominal oxide-based layer thickness.
To produce an oxide-based layer thickness ranging from about 30
.ANG. to about 400 .ANG., typically the partial pressure in the
process chamber of the SiCl.sub.4 vapor ranges from about 0.5 Torr
to about 4 Torr, more typically from about 1 Torr to about 3 Torr.
Typically, within about 10 seconds of injection of the SiCl.sub.4
vapor, water vapor was injected at a specific partial pressure
ratio to the SiCl.sub.4 to form the adhering silicon-oxide based
layer on the substrate. Typically the partial pressure of the water
vapor ranges from about 2 Torr to about 8 Torr, and more typically
from about 4 Torr to about 6 Torr. (Several volumes of SiCl.sub.4
and/or several volumes of water may be injected into the process
chamber to achieve the total partial pressures desired, as
previously described herein.) The reaction time to produce the
oxide layer may range from about 5 minutes to about 15 minutes,
depending on the processing temperature, and in the exemplary
embodiments described herein the reaction time used was about 10
minutes at about 35.degree. C.
[0125] After deposition of the oxide-based layer, the chamber was
once again pumped down to a pressure in the range of about 30 mTorr
or less. Optionally, the processing chamber may be purged with
nitrogen up to a pressure of about 10 Torr to about 20 Torr and
then pumped down to the pressure in the range of about 30 mTorr, as
previously described. The organic-based layer deposited from an
FDTS precursor was then produced by injecting FDTS into the process
chamber to provide a partial pressure ranging from about 30 mTorr
to about 1500 mTorr, more typically ranging from about 100 mTorr to
about 300 mTorr. The exemplary embodiments described herein were
typically carried out using an FDTS partial pressure of about 150
mTorr. Within about 10 seconds after injection of the FDTS
precursor, water vapor was injected into the process chamber to
provide a partial pressure of water vapor ranging from about 300
mTorr to about 1000 mTorr, more typically ranging from about 400
mTorr to about 800 mTorr. The exemplary embodiments described
herein were typically carried out using a water vapor partial
pressure of about 600 mTorr. The reaction time for formation of the
organic-based layer (a SAM) ranged from about 5 minutes to about 30
minutes, depending on the processing temperature, more typically
from about 10 minutes to about 20 minutes, and in the exemplary
embodiments described herein the reaction time used was about 15
minutes at about 35.degree. C.
[0126] The data presented in FIG. 6 indicates that to obtain the
maximum hydrophobicity at the surface of the FDTS-layer, it is not
only necessary to have an oxide-based layer thickness which is
adequate to cover the substrate surface, but it is also necessary
to have a thicker layer in some instances, depending on the
substrate underlying the oxide-based layer Since the silicon oxide
layer is conformal, it would appear that the increased thickness is
not necessary to compensate for roughness, but has a basis in the
chemical composition of the substrate. However, as a matter of
interest, the initial roughness of the silicon wafer surface was
about 0.1 RMS nm, and the initial roughness of the glass surface
was about 1-2 RMS nm.
[0127] The FIG. 6 graph 600 shows the contact angle of a DI water
droplet, in degrees, on axis 624, as measured for an oxide-based
layer surface over different substrates, as a function of the
thickness of the oxide-based layer in Angstroms shown on axis 622.
Curve 626 illustrates a silicon-oxide-based layer deposited over a
single crystal silicon wafer surface. Curve 628 represents a
silicon-oxide-based layer deposited over a glass surface. Curve 630
illustrates a silicon-oxide-based layer deposited over a
polystyrene surface. Curve 632 shows a silicon-oxide-based layer
deposited over an acrylic surface. The FDTS-generated SAM layer
provides an upper surface containing fluorine atoms, which is
generally hydrophobic in nature. The maximum contact angle provided
by this fluorine-containing upper surface is about 117 degrees. As
illustrated in FIG. 6, this maximum contact angle, indicating an
FDTS layer covering the entire substrate surface is only obtained
when the underlying oxide-based layer also covers the entire
substrate surface at a particular minimum thickness. There appears
to be another factor which requires a further increase in the
oxide-based layer thickness, over and above the thickness required
to fully cover the substrate, with respect to some substrates. It
appears this additional increase in oxide-layer thickness is
necessary to fully isolate the surface organic-based layer, a
self-aligned-monolayer (SAM), from the effects of the underlying
substrate. It is important to keep in mind that the thickness of
the SAM deposited from the FDTS layer is only about 10 .ANG. to
about 20 .ANG..
[0128] The stability of the deposited SAM organic-based layers can
be increased by baking for about one half hour at 110.degree. C.,
to crosslink the organic-based layers. Baking of a single pair of
layers is not adequate to provide the stability which is observed
for the multilayered structure, but baking can even further improve
the performance of the multilayered structure.
[0129] The integrated method for creating a multilayered structure
of the kind described above includes: Treatment of the substrate
surface to remove contaminants and to provide either --OH or
halogen moieties on the substrate surface, typically the
contaminants are removed using a low density oxygen plasma, or
ozone, or ultra violet (UV) treatment of the substrate surface. The
--OH or halogen moieties are commonly provided by deposition of an
oxide-based layer in the manner previously described herein. At
least one SAM or other functional organic layer is then vapor
deposited over the oxide-based layer surface.
[0130] It is also possible to apply a hydrophobic exterior layer to
a golf ball surface using an amine-functionalized perfluoro organic
precursor. An example precursor is
icosakaihena-fluoro-1,1,2,2-tetrahydro-dodecyl-(tris-dimethylamino)
silane. A tris-amine provides excellent bonding directly to the
golf ball surface, without the need for an oxide bonding layer.
Four injections of the precursor from a 300 cc reservoir, where the
reservoir pressure was 250 mTorr per injection was used. A reaction
time of about 15 minutes at about 35.degree. C. provided an
excellent hydrophobic exterior coating.
[0131] The above described exemplary embodiments are not intended
to limit the scope of the present invention, as one skilled in the
art can, in view of the present disclosure expand such embodiments
to correspond with the subject matter of the invention claimed
below.
* * * * *
References