U.S. patent application number 13/452370 was filed with the patent office on 2012-08-09 for composite articles and methods for making the same.
This patent application is currently assigned to Taylor Made Golf Company, Inc.. Invention is credited to Bing-Ling Chao.
Application Number | 20120199282 13/452370 |
Document ID | / |
Family ID | 39541192 |
Filed Date | 2012-08-09 |
United States Patent
Application |
20120199282 |
Kind Code |
A1 |
Chao; Bing-Ling |
August 9, 2012 |
COMPOSITE ARTICLES AND METHODS FOR MAKING THE SAME
Abstract
The present disclosure pertains to composite articles, and in
particular a composite face plate for a golf club-head, and methods
for making the same. In certain embodiments, a composite face plate
for a club-head comprises a lay-up of multiple, composite prepreg
plies. The face plate can be made by first forming an oversized
lay-up of multiple prepreg plies having a central portion and a
sacrificial portion surrounding the central portion. The lay-up is
at least partially cured in a mold under elevated pressure and
heat. The lay-up is then removed from the mold and the sacrificial
portion is removed from the central portion to form a composite
part that is substantially free of defects.
Inventors: |
Chao; Bing-Ling; (San Diego,
CA) |
Assignee: |
Taylor Made Golf Company,
Inc.
|
Family ID: |
39541192 |
Appl. No.: |
13/452370 |
Filed: |
April 20, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12970804 |
Dec 16, 2010 |
8163119 |
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13452370 |
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12156947 |
Jun 3, 2008 |
7874938 |
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12970804 |
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|
12004386 |
Dec 19, 2007 |
7874936 |
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12156947 |
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11825138 |
Jul 2, 2007 |
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12004386 |
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11895195 |
Aug 21, 2007 |
7628712 |
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12156947 |
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10442348 |
May 21, 2003 |
7267620 |
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11895195 |
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60877336 |
Dec 26, 2006 |
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Current U.S.
Class: |
156/250 ;
156/307.1 |
Current CPC
Class: |
B29K 2707/04 20130101;
B29C 70/30 20130101; B29K 2063/00 20130101; B29C 70/342 20130101;
Y10T 156/108 20150115; Y10T 156/1052 20150115 |
Class at
Publication: |
156/250 ;
156/307.1 |
International
Class: |
B32B 37/14 20060101
B32B037/14; B32B 37/06 20060101 B32B037/06; B32B 37/10 20060101
B32B037/10; B32B 38/04 20060101 B32B038/04 |
Claims
1. A method for making a composite face plate for a club-head of a
golf club, the method comprising: forming a lay-up of multiple
prepreg plies, each prepreg ply comprising at least one layer of
reinforcing fibers impregnated with a resin, the lay-up comprising
a central portion and a sacrificial portion surrounding the central
portion; placing the lay-up in a molding tool having an initial
tool temperature T.sub.i and initial pressure P.sub.1, wherein
P.sub.1 is at least atmospheric pressure; at an initial time
t.sub.0, commencing a progressive increase in tool temperature from
T.sub.i while maintaining the lay-up at the pressure P.sub.1, to
initiate a progressive increase in lay-up temperature from T.sub.i;
at a time t.sub.1, later than t.sub.0, at which the resin exhibits
a minimal liquid viscosity, commencing a progressive increase in
pressure of the lay-up in the tool from P.sub.1, and further
increasing the tool temperature to cause the lay-up temperature in
the tool to continue increasing progressively toward a
predetermined temperature T.sub.s>T.sub.i; from the time t.sub.1
to a later time t.sub.2, allowing the lay-up temperature in the
tool to increase further toward T.sub.s while further progressively
increasing the pressure of the lay-up in the tool toward a
predetermined pressure P.sub.2>P.sub.1, during which the resin
exhibits a relatively rapid progressive increase in viscosity and
reaches the pressure P.sub.2 at the time t.sub.2; and from the time
t.sub.2 to a predetermined later time t.sub.3, allowing the lay-up
temperature to increase further toward the temperature T.sub.s
while the lay-up remains substantially at the pressure P.sub.2,
thereby allowing the resin to undergo a relatively slow but
continued increase in viscosity to a specified pre-cure viscosity
level; at least partially curing the lay-up in a mold so as to form
an at least partially cured lay-up having a bulge and roll;
removing the at least partially cured lay-up from the mold; and
after removing the at least partially cured lay-up from the mold,
removing the sacrificial portion from the central portion of the at
least partially cured lay-up to form a composite part having
specified dimensions and shape for use as a face plate or part of a
face plate in a club-head.
2. The method of claim 1, wherein the act of at least partially
curing the lay-up leaves no more than one void in the central
portion of the partially cured lay-up.
3. The method of claim 1, wherein, prior to the act of removing,
the fibers of each ply have opposite end portions that extend into
the sacrificial portion, and the act of removing the sacrificial
portion is effective to separate the end portions of the fibers
from the plies forming the composite part.
4. The method of claim 1, wherein, prior to the act of removing,
the sacrificial portion completely surrounds the central
portion.
5. The method of claim 1, wherein the part, after removing the
sacrificial portion, has a void content of about
1.7.times.10.sup.-6 percent or less by volume.
6. The method of claim 1, wherein the part, after removing the
sacrificial portion, does not have any voids.
7. The method of claim 1, wherein the act of removing the
sacrificial portion comprises water-jet cutting the sacrificial
portion from the central portion.
8. The method of claim 1, further comprising placing an outer layer
on the composite part, the outer layer defining a striking surface
of the face plate.
9. The method of claim 8, wherein the outer layer comprises a
polymeric layer.
10. The method of claim 8, wherein the outer layer comprises a
metal layer.
11. The method of claim 10, wherein the metal layer is made of
titanium, aluminum, magnesium, steel, or alloys thereof.
12. The method of claim 1, wherein the lay-up has a varying
thickness.
13. The method of claim 1, wherein the resin comprises a thermoset
resin.
14. The method of claim 1, further comprising mounting the
composite part to the club-head.
15. The method of claim 1, wherein the club-head defines a front
opening and the method further comprises mounting the composite
part to the club-head so as to cover the front opening.
16. The method of claim 1, wherein the central portion of the
lay-up has first and second opposing surfaces and a thickness
measured from the first surface to the second surface, and the act
of removing the sacrificial portion forms an outer peripheral edge
of the composite part that extends from the first surface to the
second surface.
17. The method of claim 1, wherein the pressure P.sub.1 is within a
range 0-100 psig.
18. The method of claim 1, wherein the pressure P.sub.1 is within
the range 0-150.
19. The method of claim 1, wherein the pressure P.sub.2 is within a
range 200-500 psig.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S.
application Ser. No. 12/970,804, filed Dec. 16, 2010, which is a
continuation of U.S. application Ser. No. 12/156,947, filed Jun. 3,
2008, now U.S. Pat. No. 7,874,938, which is a continuation of U.S.
application Ser. No. 12/004,386, filed Dec. 19, 2007, now U.S. Pat.
No. 7,874,936. U.S. application Ser. No. 12/156,947 is also a
continuation-in-part of U.S. application Ser. No. 11/825,138, filed
Jul. 2, 2007, which claims the benefit of U.S. Provisional
Application No. 60/877,336, filed on Dec. 26, 2006. U.S.
application Ser. No. 12/156,947 is also a continuation-in-part of
U.S. application Ser. No. 11/895,195, filed Aug. 21, 2007, now U.S.
Pat. No. 7,628,712, which is a continuation of U.S. application
Ser. No. 10/442,348, filed May 21, 2003, now U.S. Pat. No.
7,267,620. U.S. application Ser. Nos. 12/970,804, 12/156,947,
12/004,386, 11/825,138, 60/877,336, 11/895,195, and 10/442,348 are
incorporated herein by reference.
FIELD
[0002] This disclosure pertains generally to composite articles.
More particularly, the disclosure pertains to, inter alia, golf
clubs and club-heads that have a composite face insert.
BACKGROUND
[0003] With the ever-increasing popularity and competitiveness of
golf, substantial effort and resources are currently being expended
to improve golf clubs so that increasingly more golfers can have
more enjoyment and more success at playing golf. Much of this
improvement activity has been in the realms of sophisticated
materials and club-head engineering. For example, modern
"wood-type" golf clubs (notably, "drivers," "fairway woods," and
"utility clubs"), with their sophisticated shafts and non-wooden
club-heads, bear little resemblance to the "wood" drivers, low-loft
long-irons, and higher numbered fairway woods used years ago. These
modern wood-type clubs are generally called "metal-woods."
[0004] An exemplary metal-wood golf club such as a fairway wood or
driver typically includes a hollow shaft having a lower end to
which the club-head is attached. Most modern versions of these
club-heads are made, at least in part, of a light-weight but strong
metal such as titanium alloy. The club-head comprises a body to
which a strike plate (also called a face plate) is attached or
integrally formed. The strike plate defines a front surface or
strike face that actually contacts the golf ball.
[0005] The current ability to fashion metal-wood club-heads of
strong, light-weight metals and other materials has allowed the
club-heads to be made hollow. Use of materials of high strength and
high fracture toughness has also allowed club-head walls to be made
thinner, which has allowed increases in club-head size, compared to
earlier club-heads. Larger club-heads tend to provide a larger
"sweet spot" on the strike plate and to have higher club-head
inertia, thereby making the club-heads more "forgiving" than
smaller club-heads. Characteristics such as size of the sweet spot
are determined by many variables including the shape profile, size,
and thickness of the strike plate as well as the location of the
center of gravity (CG) of the club-head.
[0006] The distribution of mass around the club-head typically is
characterized by parameters such as rotational moment of inertia
(MOI) and CG location. Club-heads typically have multiple
rotational MOIs, each associated with a respective Cartesian
reference axis (x, y, z) of the club-head. A rotational MOI is a
measure of the club-head's resistance to angular acceleration
(twisting or rotation) about the respective reference axis. The
rotational MOIs are related to, inter alia, the distribution of
mass in the club-head with respect to the respective reference
axes. Each of the rotational MOIs desirably is maximized as much as
practicable to provide the club-head with more forgiveness.
[0007] Another factor in modern club-head design is the face plate.
Impact of the face plate with the golf ball results in some
rearward instantaneous deflection of the face plate. This
deflection and the subsequent recoil of the face plate are
expressed as the club-head's coefficient of restitution (COR). A
thinner face plate deflects more at impact with a golf ball and
potentially can impart more energy and thus a higher rebound
velocity to the struck ball than a thicker or more rigid face
plate. Because of the importance of this effect, the COR of clubs
is limited under United States Golf Association (USGA) rules.
[0008] Regarding the total mass of the club-head as the club-head's
mass budget, at least some of the mass budget must be dedicated to
providing adequate strength and structural support for the
club-head. This is termed "structural" mass. Any mass remaining in
the budget is called "discretionary" or "performance" mass, which
can be distributed within the club-head to address performance
issues, for example.
[0009] Some current approaches to reducing structural mass of a
club-head are directed to making at least a portion of the
club-head of an alternative material. Whereas the bodies and face
plates of most current metal-woods are made of titanium alloy,
several "hybrid" club-heads are available that are made, at least
in part, of components formed from both graphite/epoxy-composite
(or another suitable composite material) and a metal alloy. For
example, in one group of these hybrid club-heads a portion of the
body is made of carbon-fiber (graphite)/epoxy composite and a
titanium alloy is used as the primary face-plate material. Other
club-heads are made entirely of one or more composite materials.
Graphite composites have a density of approximately 1.5 g/cm.sup.3,
compared to titanium alloy which has a density of 4.5 g/cm.sup.3,
which offers tantalizing prospects of providing more discretionary
mass in the club-head.
[0010] Composite materials that are useful for making club-head
components comprise a fiber portion and a resin portion. In general
the resin portion serves as a "matrix" in which the fibers are
embedded in a defined manner. In a composite for club-heads, the
fiber portion is configured as multiple fibrous layers or plies
that are impregnated with the resin component. The fibers in each
layer have a respective orientation, which is typically different
from one layer to the next and precisely controlled. The usual
number of layers is substantial, e.g., fifty or more. During
fabrication of the composite material, the layers (each comprising
respectively oriented fibers impregnated in uncured or partially
cured resin; each such layer being called a "prepreg" layer) are
placed superposedly in a "lay-up" manner. After forming the prepreg
lay-up, the resin is cured to a rigid condition.
[0011] Conventional processes by which fiber-resin composites are
fabricated into club-head components utilize high (and sometimes
constant) pressure and temperature to cure the resin portion in a
minimal period of time. The processes desirably yield components
that are, or nearly are, "net-shape," by which is meant that the
components as formed have their desired final configurations and
dimensions. Making a component at or near net-shape tends to reduce
cycle time for making the components and to reduce finishing costs.
Unfortunately, at least three main defects are associated with
components made in this conventional fashion: (a) the components
exhibit a high incidence of composite porosity (voids formed by
trapped air bubbles or as a result of the released gases during a
chemical reaction); (b) a relatively high loss of resin occurs
during fabrication of the components; and (c) the fiber layers tend
to have "wavy" fibers instead of straight fibers. Whereas some of
these defects may not cause significant adverse effects on the
service performance of the components when the components are
subjected to simple (and static) tension, compression, and/or
bending, component performance typically will be drastically
reduced whenever these components are subjected to complex loads,
such as dynamic and repetitive loads (i.e., repetitive impact and
consequent fatigue).
[0012] Manufacturers of metal wood golf club-heads have more
recently attempted to manipulate the performance of their club
heads by designing what is generically termed a variable face
thickness profile for the striking face. It is known to fabricate a
variable-thickness composite striking plate by first forming a
lay-up of prepreg plies, as described above, and then adding
additional "partial" layers or plies that are smaller than the
overall size of the plate in the areas where additional thickness
is desired (referred to as the "partial ply" method). For example,
to form a projection on the rear surface of a composite plate, a
series of annular plies, gradually decreasing in size, are added to
the lay-up of prepreg plies.
[0013] Unfortunately, variable-thickness composite plates
manufactured using the partial ply method are susceptible to a high
incidence of composite porosity because air bubbles tend to remain
at the edges of the partial plies (within the impact zone of the
plate). Moreover, the reinforcing fibers in the prepreg plies are
ineffective at their ends. The ends of the fibers of the partial
plies within the impact zone are stress concentrations, which can
lead to premature delamination and/or cracking. Furthermore, the
partial plies can inhibit the steady outward flow of resin during
the curing process, leading to resin-rich regions in the plate.
Resin-rich regions tend to reduce the efficacy of the fiber
reinforcement, particularly since the force resulting from
golf-ball impact is generally transverse to the orientation of the
fibers of the fiber reinforcement.
[0014] Typically, conventional CNC machining is used during the
manufacture of composite face plates, such as for trimming a cured
part. Because the tool applies a lateral cutting force to the part
(against the peripheral edge of the part), it has been found that
such trimming can pull fibers or portions thereof out of their
plies and/or induce horizontal cracks on the peripheral edge of the
part. As can be appreciated, these defects can cause premature
delamination and/or other failure of the part.
[0015] While durability limits the application of non-metals in
striking plates, even durable plastics and composites exhibit some
additional deficiencies. Typical metallic striking plates include a
fine ground striking surface (and for iron-type golf clubs may
include a series of horizontal grooves) that tends to promote a
preferred ball spin in play under wet conditions. This fine ground
surface appears to provide a relief volume for water present at a
striking surface/ball impact area so that impact under wet
conditions produces a ball trajectory and shot characteristics
similar to those obtained under dry conditions. While non-metals
suitable for striking plates are durable, these materials generally
do not provide a durable roughened, grooved, or textured striking
surface such as provided by conventional clubs and that is needed
to maintain club performance under various playing conditions.
Accordingly, improved striking plates, striking surfaces, and golf
clubs that include such striking plates and surfaces and associated
methods are needed.
SUMMARY
[0016] Some disclosed examples pertain to composite articles, and
in particular a composite face plate for a golf club-head, and
methods for making the same. In certain embodiments, a composite
face plate for a club-head is formed with a cross-sectional profile
having a varying thickness. The face plate comprises a lay-up of
multiple, composite prepreg plies. The face plate can include
additional components, such as an outer polymeric or metal layer
(also referred to as a cap) covering the outer surface of the
lay-up and forming the striking surface of the face plate. In other
embodiments, the outer surface of the lay-up can be the striking
surface that contacts a golf ball upon impact with the face
plate.
[0017] In order to vary the thickness of the lay-up, some of the
prepreg plies comprise elongated strips of prepreg material
arranged in a cross-cross, overlapping pattern so as to add
thickness to the composite lay-up in one or more regions where the
strips overlap each other. The strips of prepreg plies can be
arranged relative to each other in a predetermined manner to
achieve a desired cross-sectional profile for the face plate. For
example, in one embodiment, the strips can be arranged in one or
more clusters having a central region where the strips overlap each
other. The lay-up has a projection or bump formed by the central
overlapping region of the strips and desirably centered on the
sweet spot of the face plate. A relatively thinner peripheral
portion of the lay-up surrounds the projection. In another
embodiment, the lay-up can include strips of prepreg plies that are
arranged to form an annular projection surrounding a relatively
thinner central region of the face plate, thereby forming a
cross-sectional profile that is reminiscent of a "volcano."
[0018] The strips of prepreg material desirably extend continuously
across the finished composite part; that is, the ends of the strips
are at the peripheral edge of the finished composite part. In this
manner, the longitudinally extending reinforcing fibers of the
strips also extend continuously across the finished composite part
such that the ends of the fibers are at the periphery of the part.
In addition, the lay-up can initially be formed as an "oversized"
part in which the reinforcing fibers of the prepreg material extend
into a peripheral sacrificial portion of the lay-up. Consequently,
the curing process for the lay-up can be controlled to shift
defects into the sacrificial portion of the lay-up, which
subsequently can be removed to provide a finished part with little
or no defects. Moreover, the durability of the finished part is
increased because the free ends of the fibers are at the periphery
of the finished part, away from the impact zone.
[0019] The sacrificial portion desirably is trimmed from the lay-up
using water-jet cutting. In water-jet cutting, the cutting force is
applied in a direction perpendicular to the prepreg plies (in a
direction normal to the front and rear surfaces of the lay-up),
which minimizes damage to the reinforcing fibers.
[0020] In one representative embodiment, a golf club-head comprises
a body having a crown, a heel, a toe, and a sole, and defining a
front opening. The head also includes a variable-thickness face
insert closing the front opening of the body. The insert comprises
a lay-up of multiple, composite prepreg plies, wherein at least a
portion of the plies comprise a plurality of elongated prepreg
strips arranged in a criss-cross pattern defining an overlapping
region where the strips overlap each other. The lay-up has a first
thickness at a location spaced from the overlapping region and a
second thickness at the overlapping region, the second thickness
being greater than the first thickness.
[0021] In another representative embodiment, a golf club-head
comprises a body having a crown, a heel, a toe, and a sole, and
defining a front opening. The head also includes a
variable-thickness face insert closing the front opening of the
body. The insert comprises a lay-up of multiple, composite prepreg
plies, the lay-up having a front surface, a peripheral edge
surrounding the front surface, and a width. At least a portion of
the plies comprise elongated strips that are narrower than the
width of the lay-up and extend continuously across the front
surface. The strips are arranged within the lay-up so as to define
a cross-sectional profile having a varying thickness.
[0022] In another representative embodiment, a composite face plate
for a club-head of a golf club comprises a composite lay-up
comprising multiple prepreg layers, each prepreg layer comprising
at least one resin-impregnated layer of longitudinally extending
fibers at a respective orientation. The lay-up has an outer
peripheral edge defining an overall size and shape of the lay-up.
At least a portion of the layers comprise a plurality of composite
panels, each panel comprising a set of one or more prepreg layers,
each prepreg layer in the panels having a size and shape that is
the same as the overall size and shape of the lay-up. Another
portion of the layers comprise a plurality of sets of elongated
strips, the sets of strips being interspersed between the panels
within the lay-up. The strips extend continuously from respective
first locations on the peripheral edge to respective second
locations on the peripheral edge and define one or more areas of
increased thickness of the lay-up where the strips overlap within
the lay-up.
[0023] In another representative embodiment, a method for making a
composite face plate for a club-head of a golf club comprises
forming a lay-up of multiple prepreg composite plies, a portion of
the plies comprising elongated strips arranged in a criss-cross
pattern defining one or more areas of increased thickness in the
lay-up where one or more of the strips overlap each other. The
method can further include at least partially curing the lay-up,
and shaping the at least partially cured lay-up to form a part
having specified dimensions and shape for use as a face plate or
part of a face plate for a club-head.
[0024] In still another representative embodiment, a method for
making a composite face plate for a club-head of a golf club
comprises forming a lay-up of multiple prepreg plies, each prepreg
ply comprising at least one layer of reinforcing fibers impregnated
with a resin. The method can further include at least partially
curing the lay-up, and water-jet cutting the at least partially
cured lay-up to form a composite part having specified dimensions
and shape for use as a face plate or part of a face plate in a
club-head.
[0025] In some examples, golf club heads comprise a club body and a
striking plate secured to the club body. The striking plate
includes a face plate and a cover plate secured to the face plate
and defining a striking surface, wherein the striking surface
includes a plurality of scoreline indentations. In some examples,
an adhesive layer secures the cover plate to the face plate. In
other alternative embodiments, the scoreline indentations are at
least partially filled with a pigment selected to contrast with an
appearance of an impact area of the striking surface and the cover
plate is metallic and has a thickness between about 0.25 mm and
0.35 mm. In further examples, the scoreline indentations are
between about 0.05 and 0.09 mm deep. In other representative
examples, a ratio of a scoreline indentation width to a cover plate
thickness is between about 2.5 and 3.5, and the face plate is
formed of a titanium alloy. In some examples, the scoreline
indentations include transition regions having radii of between
about 0.2 mm and 0.6 mm, and the cover plate includes a rim
configured to extend around a perimeter of the face plate.
According to some embodiments, the face plate is a composite face
plate and the club body is a wood-type club body.
[0026] Cover plates for a golf club face plate comprise a titanium
alloy sheet having bulge and roll curvatures, and including a
plurality of scoreline indentations. A scoreline indentation depth
D is between about 0.05 mm and 0.12 mm, and a titanium alloy sheet
thickness T is between about 0.20 mm and 0.40 mm.
[0027] In further examples, golf club heads comprise a club body
and a striking plate secured to the club body. The striking plate
includes a metallic cover having a plurality of impact resistant
scoreline indentations situated on a striking surface. In some
examples, the metallic cover is between about 0.2 mm and 1.0 mm
thick and the scoreline indentations have depths between about 0.1
mm and 0.02 mm. In further examples, the scoreline indentations
have a depth D and the metallic cover has a thickness T such that a
ratio D/T is between about 0.15 and 0.30 or between about 0.20 and
0.25. In additional examples, the face plate is a variable
thickness face plate.
[0028] Methods comprise selecting a metallic cover sheet and
trimming the metallic cover sheet so as to conform to a golf club
face plate. The metallic cover sheet provides a striking surface
for a golf club. A plurality of scoreline indentations are defined
in the striking surface, wherein the metallic cover sheet has a
thickness T between about 0.1 mm and 0.5 mm, and the scoreline
indentations have a depth D such that a ratio D/T is between about
0.1 and 0.4. In additional examples, a rim is formed on the cover
sheet and is configured to cover a perimeter of the face plate. In
typical examples, the metallic sheet is a titanium alloy sheet and
is trimmed after formation of the scoreline indentations. In some
examples, the scoreline indentations are formed in an impact area
of the striking surface or outside of an impact area of the
striking surface.
[0029] According to some examples, golf club heads (wood-type or
iron-type) comprise a club body and a striking plate secured to the
club body. The striking plate includes a composite face plate
having a front surface and a polymer cover layer secured to the
front surface of the face plate, the polymer cover layer having a
textured striking surface. In some embodiments, a thickness of the
cover layer is between about 0.1 mm and about 2.0 mm or about 0.2
mm and 1.2 mm, or the thickness of the cover layer is about 0.4 mm.
In further examples, the striking face of the composite face plate
has an effective Shore D hardness of at least about 75, 80, or 85.
In additional representative examples, the textured striking
surface has one or more of a mean surface roughness between about 1
.mu.m and 10 .mu.m, a mean surface feature frequency of at least
about 2/mm, or a surface profile kurtosis greater than about 1.5,
1.75, or 2.0. In additional embodiments, the textured striking
surface has a mean surface roughness of less than about 4.5 .mu.m,
a mean surface feature frequency of at least about 3/mm, and a
surface profile kurtosis greater than about 2 as measured in a
top-to-bottom direction, a toe-to-heel direction, or along both
directions. In some examples, the striking surface is textured
along a top-to-bottom direction or a toe-to-heel direction only. In
other examples, the striking surface is textured along an axis that
is tilted with respect to a toe-to-heel and a top-to-bottom
direction.
[0030] Methods comprise providing a face plate for a golf club and
a cover layer for a front surface of the face plate. A striking
surface of the cover layer is patterned so as to provide a
roughened or textured striking surface. According to some examples,
the roughened striking surface is patterned to include a periodic
array of surface features that provide a mean roughness less than
about 5 .mu.m and a mean surface feature frequency along at least
one axis substantially parallel to the striking surface of at least
2/mm. In other examples, the striking surface of the cover layer is
patterned with a mold. In further examples, the striking surface is
patterned by pressing a fabric against the cover layer, and
subsequently removing the fabric. In a representative example, the
cover layer is formed of a thermoplastic and the fabric is applied
as the cover layer is formed.
[0031] Golf club heads comprise a face plate having a front surface
and a control layer situated on the front surface of the face
plate, wherein the control layer has a striking surface having a
surface roughness configured to provide a ball spin of about 2500
rpm, 3000 rpm, or 3500 rpm under wet conditions. In some examples,
the control layer is a polymer layer. In further examples, the
control layer is a polymer layer having a thickness of between
about 0.3 mm and 0.5 mm, and the surface roughness of the striking
surface is substantially periodic along at least one axis that is
substantially parallel to the striking surface. In a representative
examples, the striking surface of the face plate has a Shore D
hardness of at least about 75, 80, or more preferably, at least
about 85. The polymer layer can be a thermoset or thermoplastic
material. In representative examples, the polymer layer is a SURLYN
ionomer or similar material, or a urethane, preferably a
non-yellowing urethane.
[0032] The foregoing and other objects, features, and advantages of
the invention will become more apparent from the following detailed
description, which proceeds with reference to the accompanying
figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] FIG. 1 is a perspective view of a "metal-wood" club-head,
showing certain general features pertinent to the instant
disclosure.
[0034] FIG. 2 is a front elevation view of one embodiment of a
net-shape composite component used to form the strike plate of a
club-head, such as the club-head shown in FIG. 1.
[0035] FIG. 3 is a cross-sectional view taken along line 3-3 of
FIG. 2.
[0036] FIG. 4 is a cross-sectional view taken along line 4-4 of
FIG. 2.
[0037] FIG. 5 is an exploded view of one embodiment of a composite
lay-up from which the component shown in FIG. 2 can be formed.
[0038] FIG. 6 is an exploded view of a group of prepreg plies of
differing fiber orientations that are stacked to form a
"quasi-isotropic" composite panel that can be used in the lay-up
illustrated in FIG. 5.
[0039] FIG. 7 is a plan view of a group or cluster of elongated
prepreg strips that can be used in the lay-up illustrated in FIG.
5.
[0040] FIG. 8A-8C are plan views illustrating the manner in which
clusters of prepreg strips can be oriented at different rotational
positions relative to each other in a composite lay-up to create an
angular offset between the strips of adjacent clusters.
[0041] FIG. 9 is a top plan view of the composite lay-up shown in
FIG. 5.
[0042] FIGS. 10A-10C are plots of temperature, viscosity, and
pressure, respectively, versus time in a representative embodiment
of a process for forming composite components.
[0043] FIGS. 11A-11C are plots of temperature, viscosity, and
pressure, respectively, versus time in a representative embodiment
of a process in which each of these variables can be within a
specified respective range (hatched areas).
[0044] FIG. 12 is a plan view of a simplified lay-up of composite
plies from which the component shown in FIG. 2 can be formed.
[0045] FIG. 13 is a front elevation view of another net-shape
composite component that can be used to form the strike plate of a
club-head.
[0046] FIG. 14 is a cross-sectional view taken along line 14-14 of
FIG. 13.
[0047] FIG. 15 is a cross-sectional view taken along line 15-15 of
FIG. 13.
[0048] FIG. 16 is a top plan view of one embodiment of a lay-up of
composite plies from which the component shown in FIG. 13 can be
formed.
[0049] FIG. 17 is an exploded view of the first few groups of
composite plies that are used to form the lay-up shown in FIG.
16.
[0050] FIG. 18 is a partial sectional view of the upper lip region
of an embodiment of a club-head of which the face plate comprises a
composite plate and a metal cap.
[0051] FIG. 19 is a partial sectional view of the upper lip region
of an embodiment of a club-head of which the face plate comprises a
composite plate and a polymeric outer layer.
[0052] FIGS. 20-23 illustrate a metallic cover for a composite face
plate.
[0053] FIG. 24 is a side perspective view of a wood-type golf club
head.
[0054] FIG. 25 is a front perspective view of a wood-type golf club
head.
[0055] FIG. 26 is a top perspective view of a wood-type golf club
head.
[0056] FIG. 27 is a back perspective view of a wood-type golf club
head.
[0057] FIG. 28 is a front perspective view of a wood-type golf club
head showing a golf club head center of gravity coordinate
system.
[0058] FIG. 29 is a top perspective view of a wood-type golf club
head showing a golf club head center of gravity coordinate
system.
[0059] FIG. 30 is a front perspective view of a wood-type golf club
head showing a golf club head origin coordinate system.
[0060] FIG. 31 is a top perspective view of a wood-type golf club
head showing a golf club head origin coordinate system.
[0061] FIGS. 32-34 illustrate a striking plate that includes a face
plate and a cover layer having a striking surface with a patterned
roughness.
[0062] FIG. 35 illustrates attachment of a striking plate
comprising a face plate and a cover layer to a club body.
[0063] FIGS. 36-37 illustrate a representative striking plate that
includes a cover layer having a roughened striking surface.
[0064] FIGS. 38-39 illustrate a representative striking plate that
includes a cover layer having a roughened striking surface.
[0065] FIGS. 40-42 illustrate another representative striking plate
that includes a cover layer having a roughened striking
surface.
[0066] FIGS. 43-44 are surface profiles of a representative
textured striking surface of polymer layer produced with a peel ply
fabric.
[0067] FIG. 45 is a photograph of a portion of a peel ply fabric
textured surface.
[0068] FIGS. 46-48 illustrate another representative striking plate
that includes a cover layer having a roughened striking
surface.
[0069] FIG. 49 is a surface profile of the roughened surface of
FIGS. 46-48.
DETAILED DESCRIPTION
[0070] This disclosure is set forth in the context of
representative embodiments that are not intended to be limiting in
any way.
[0071] In the following description, certain terms may be used such
as "up," "down,", "upper," "lower," "horizontal," "vertical,"
"left," "right," and the like. These terms are used, where
applicable, to provide some clarity of description when dealing
with relative relationships. But, these terms are not intended to
imply absolute relationships, positions, and/or orientations. For
example, with respect to an object, an "upper" surface can become a
"lower" surface simply by turning the object over. Nevertheless, it
is still the same object.
[0072] As used herein, the singular forms "a," "an," and "the"
refer to one or more than one, unless the context clearly dictates
otherwise.
[0073] As used herein, the term "includes" means "comprises." For
example, a device that includes or comprises A and B contains A and
B but may optionally contain C or other components other than A and
B. A device that includes or comprises A or B may contain A or B or
A and B, and optionally one or more other components such as C.
[0074] As used herein, the term "composite" or "composite
materials" means a fiber-reinforced polymeric material.
[0075] The main features of an exemplary hollow "metal-wood"
club-head 10 are depicted in FIG. 1. The club-head 10 comprises a
face plate, strike plate, or striking plate 12 and a body 14. The
face plate 12 typically is convex, and has an external ("striking")
surface (face) 13. The body 14 defines a front opening 16. A face
support 18 is disposed about the front opening 16 for positioning
and holding the face plate 12 to the body 14. The body 14 also has
a heel 20, a toe 22, a sole 24, a top or crown 26, and a hosel 28.
Around the front opening 16 is a "transition zone" 15 that extends
along the respective forward edges of the heel 20, the toe 22, the
sole 24, and the crown 26. The transition zone 15 effectively is a
transition from the body 14 to the face plate 12. The face support
18 can comprise a lip or rim that extends around the front opening
16 and is released relative to the transition zone 15 as shown. The
hosel 28 defines an opening 30 that receives a distal end of a
shaft (not shown). The opening 16 receives the face plate 12, which
rests upon and is bonded to the face support 18 and transition zone
15, thereby enclosing the front opening 16. The transition zone 15
can include a sole-lip region 18d, a crown-lip region 18a, a
heel-lip region 18c, and a toe-lip region 18b. These portions can
be contiguous, as shown, or can be discontinuous, with spaces
between them.
[0076] In a club-head according to one embodiment, at least a
portion of the face plate 12 is made of a composite including
multiple plies or layers of a fibrous material (e.g., graphite, or
carbon, fiber) embedded in a cured resin (e.g., epoxy). For
example, the face plate 12 can comprise a composite component
(e.g., component 40 shown in FIGS. 2-4) that has an outer polymeric
layer forming the striking surface 13. Examples of suitable
polymers that can be used to form the outer coating, or cap, are
described in detail below. Alternatively, the face plate 12 can
have an outer metallic cap forming the external striking surface 13
of the face plate, as described in U.S. Pat. No. 7,267,620, which
is incorporated herein by reference.
[0077] An exemplary thickness range of the composite portion of the
face plate is 7.0 mm or less. The composite desirably is configured
to have a relatively consistent distribution of reinforcement
fibers across a cross-section of its thickness to facilitate
efficient distribution of impact forces and overall durability. In
addition, the thickness of the face plate 12 can be varied in
certain areas to achieve different performance characteristics
and/or improve the durability of the club-head. The face plate 12
can be formed with any of various cross-sectional profiles,
depending on the club-head's desired durability and overall
performance, by selectively placing multiple strips of composite
material in a predetermined manner in a composite lay-up to form a
desired profile.
[0078] Attaching the face plate 12 to the support 18 of the
club-head body 14 may be achieved using an appropriate adhesive
(typically an epoxy adhesive or a film adhesive). To prevent peel
and delamination failure at the junction of an all-composite face
plate with the body of the club-head, the composite face plate can
be recessed from or can be substantially flush with the plane of
the forward surface of the metal body at the junction. Desirably,
the face plate is sufficiently recessed so that the ends of the
reinforcing fibers in the composite component are not exposed.
[0079] The composite portion of the face plate is made as a lay-up
of multiple prepreg plies. For the plies the fiber reinforcement
and resin are selected in view of the club-head's desired
durability and overall performance. In order to vary the thickness
of the lay-up, some of the prepreg plies comprise elongated strips
of prepreg material arranged in one or more sets of strips. The
strips in each set are arranged in a cross-cross, overlapping
pattern so as to add thickness to the composite lay-up in the
region where the strips overlap each other, as further described in
greater detail below. The strips desirably extend continuously
across the finished composite part; that is, the ends of the strips
are at the peripheral edge of the finished composite part. In this
manner, the longitudinally extending reinforcing fibers of the
strips also can extend continuously across the finished composite
part such that the ends of the fibers are at the periphery of the
part. Consequently, during the curing process, defects can be
shifted toward a peripheral sacrificial portion of the composite
lay-up, which sacrificial portion subsequently can be removed to
provide a finished part with little or no defects. Moreover, the
durability of the finished part is increased because the free ends
of the fibers are at the periphery of the finished part, away from
the impact zone.
[0080] In tests involving certain club-head configurations,
composite portions formed of prepreg plies having a relatively low
fiber areal weight (FAW) have been found to provide superior
attributes in several areas, such as impact resistance, durability,
and overall club performance. (FAW is the weight of the fiber
portion of a given quantity of prepreg, in units of g/m.sup.2.) FAW
values below 100 g/m.sup.2, and more desirably below 70 g/m.sup.2,
can be particularly effective. A particularly suitable fibrous
material for use in making prepreg plies is carbon fiber, as noted.
More than one fibrous material can be used. In other embodiments,
however, prepreg plies having FAW values above 100 g/m.sup.2 may be
used.
[0081] In particular embodiments, multiple low-FAW prepreg plies
can be stacked and still have a relatively uniform distribution of
fiber across the thickness of the stacked plies. In contrast, at
comparable resin-content (R/C, in units of percent) levels, stacked
plies of prepreg materials having a higher FAW tend to have more
significant resin-rich regions, particularly at the interfaces of
adjacent plies, than stacked plies of low-FAW materials. Resin-rich
regions tend to reduce the efficacy of the fiber reinforcement,
particularly since the force resulting from golf-ball impact is
generally transverse to the orientation of the fibers of the fiber
reinforcement.
[0082] FIGS. 2-4 show an exemplary embodiment of a finished
component 40 that is fabricated from a plurality of prepreg plies
or layers and has a desired shape and size for use as a face plate
for a club-head or as part of a face plate for a clubhead. The
composite part 40 has a front surface 42 and a rear surface 44. In
this example the composite part has an overall convex shape, a
central region 46 of increased thickness, and a peripheral region
48 having a relatively reduced thickness extending around the
central region. The central region 46 in the illustrated example is
in the form of a projection or cone on the rear surface having its
thickest portion at a central point 50 (FIG. 3) and gradually
tapering away from the point in all directions toward the
peripheral region 48. The central point 50 represents the
approximate center of the "sweet spot" (optimal strike zone) of the
face plate 12, but not necessarily the geometric center of the face
plate. The thicker central region 46 adds rigidity to the central
area of the face plate 12, which effectively provides a more
consistent deflection across the face plate. In certain
embodiments, the central region 46 has a thickness of about 5 mm to
about 7 mm and the peripheral region 48 has a thickness of about 4
mm to about 5 mm.
[0083] In certain embodiments, the composite component 40 is
fabricated by first forming an oversized lay-up of multiple prepreg
plies, and then machining a sacrificial portion from the cured
lay-up to form the finished part 40. FIG. 9 is a top plan view of
one example of a lay-up 38 from which the composite component 40
can be formed. The line 64 in FIG. 9 represents the outline of the
component 40. Once cured, the portion surrounding the line 64 can
be removed to form the component 40. FIG. 5 is an exploded view of
the lay-up 38. In the lay-up, each prepreg ply desirably has a
prescribed fiber orientation, and the plies are stacked in a
prescribed order with respect to fiber orientation.
[0084] As shown in FIG. 5, the illustrated lay-up 38 is comprised
of a plurality of sets, or unit-groups, 52a-52k of one or more
prepreg plies of substantially uniform thickness and one or more
sets, or unit-groups, 54a-54g of individual plies in the form of
elongated strips 56. For purposes of description, each set 52a-52k
of one or more plies can be referred to as a composite "panel" and
each set 54a-54g can be referred to as a "cluster" of elongated
strips. The clusters 54a-54g of elongated strips 56 are interposed
between the panels 52a-52k and serve to increase the thickness of
the finished part 40 at its central region 46 (FIG. 2). Each panel
52a-52k comprises one or more individual prepreg plies having a
desired fiber orientation. The individual plies forming each panel
52a-52k desirably are of sufficient size and shape to form a cured
lay-up from which the smaller finished component 40 can be formed
substantially free of defects. The clusters 54a-54g of strips 56
desirably are individually positioned between and sandwiched by two
adjacent panels (i.e., the panels 52a-52k separate the clusters
54a-54g of strips from each other) to facilitate adhesion between
the many layers of prepreg material and provide an efficient
distribution of fibers across a cross-section of the part.
[0085] In particular embodiments, the number of panels 52a-52k can
range from 9 to 14 (with eleven panels 52a-52k being used in the
illustrated embodiment) and the number of clusters 54a-54g can
range from 1 to 12 (with seven clusters 54a-54g being used in the
illustrated embodiment). However, in alternative embodiments, the
number of panels and clusters can be varied depending on the
desired profile and thickness of the part.
[0086] The prepreg plies used to form the panels 52a-52k and the
clusters 54a-54g desirably comprise carbon fibers impregnated with
a suitable resin, such as epoxy. An example carbon fiber is
"34-700" carbon fiber (available from Grafil, Sacramento, Calif.),
having a tensile modulus of 234 Gpa (34 Msi) and a tensile strength
of 4500 Mpa (650 Ksi). Another Grafil fiber that can be used is
"TR50S" carbon fiber, which has a tensile modulus of 240 Gpa (35
Msi) and a tensile strength of 4900 Mpa (710 ksi). Suitable epoxy
resins are types "301" and "350" (available from Newport Adhesives
and Composites, Irvine, Calif.). An exemplary resin content (R/C)
is 40%.
[0087] FIG. 6 is an exploded view of the first panel 52a. For
convenience of reference, the fiber orientation (indicated by lines
66) of each ply is measured from a horizontal axis of the
club-head's face plane to a line that is substantially parallel
with the fibers in the ply. As shown in FIG. 6, the panel 52a in
the illustrated example comprises a first ply 58a having fibers
oriented at +45 degrees, a second ply 58b having fibers oriented at
0 degrees, a third ply 58c having fibers oriented at -45 degrees,
and a fourth ply 58d having fibers oriented at 90 degrees. The
panel 52a of plies 58a-58d thus form a "quasi-isotropic" panel of
prepreg material. The remaining panels 52b-52k can have the same
number of prepreg plies and fiber orientation as set 52a.
[0088] The lay-up illustrated in FIG. 5 can further include an
"outermost" fiberglass ply 70 adjacent the first panel 52a, a
single carbon-fiber ply 72 adjacent the eleventh and last panel
52k, and an "innermost" fiberglass ply 74 adjacent the single ply
72. The single ply can have a fiber orientation of 90 degrees as
shown. The fiberglass plies 70, 74 can have fibers oriented at 0
degrees and 90 degrees. The fiberglass plies 70, 74 are essentially
provided as sacrificial layers that protect the carbon-fiber plies
when the cured lay-up is subjected to surface finishing such as
sand blasting to smooth the outer surfaces of the part.
[0089] FIG. 7 is an enlarged plan view of the first cluster 54a of
elongated prepreg strips which are arranged with respect to each
other so that the cluster has a variable thickness. The cluster 54a
in the illustrated example includes a first strip 56a, a second
strip 56b, a third strip 56c, a fourth strip 56d, a fifth strip
56e, a sixth strip 56f, and a seventh strip 56g. The strips are
stacked in a criss-cross pattern such that the strips overlap each
other to define an overlapping region 60 and the ends of each strip
are angularly spaced from adjacent ends of another strip. The
cluster 54a is therefore thicker at the overlapping region 60 than
it is at the ends of the strips. The strips can have the same or
different lengths and widths, which can be varied depending on the
desired overall shape of the composite part 40, although each strip
desirably is long enough to extend continuously across the finished
part 40 that is cut or otherwise machined from the oversized
lay-up.
[0090] The strips 56a-56g in the illustrated embodiment are of
equal length and are arranged such that the geometric center point
62 of the cluster corresponds to the center of each strip. The
first three strips 56a-56c in this example have a width w.sub.1
that is greater than the width w.sub.2 of the last four strips
56d-56g. The strips define an angle .alpha. between the
"horizontal" edges of the second strip 56b and the adjacent edges
of strips 56a and 56c, an angle .mu. between the edges of strip 56b
and the closest edges of strips 56d and 56g, and an angle .theta.
between the edges of strip 56b and the closest edges of strips 56e
and 56f. In a working embodiment, the width w.sub.1 is about 20 mm,
the width w.sub.2 is about 15 mm, the angle .alpha. is about 24
degrees, the angle .mu. is about 54 degrees, and the angle .theta.
is about 78 degrees.
[0091] Referring again to FIG. 5, each cluster 54a-54g desirably is
rotated slightly or angularly offset with respect to an adjacent
cluster so that the end portions of each strip in a cluster are not
aligned with the end portions of the strips of an adjacent cluster.
In this manner, the clusters can be arranged relative to each other
in the lay-up to provide a substantially uniform thickness in the
peripheral region 48 of the composite part (FIG. 3). In the
illustrated embodiment, for example, the first cluster 54a has an
orientation of -18 degrees, meaning that the "upper" edge of the
second strip 56b extends at a -18 degree angle with respect to the
"upper" horizontal edge of the adjacent unit-group 52c (as best
shown in FIG. 8A). The next successive cluster 54b has an
orientation of 0 degrees, meaning that the second strip 56b is
parallel to the "upper" horizontal edge of the adjacent unit-group
52d (as best shown in FIG. 8B). The next successive cluster 54c has
an orientation of +18 degrees, meaning that the "lower" edge of the
respective second strip 56b of cluster 54c extends at a +18 degree
angle with respect to the "lower" edge of the adjacent unit-group
52e (as best shown in FIG. 8C). Clusters 54d, 54e, 54f, and 54g
(FIG. 5) can have an orientation of 0 degrees, -18 degrees, 0
degrees, and +18 degrees, respectively.
[0092] When stacked in the lay-up, the overlapping regions 60 of
the clusters are aligned in the direction of the thickness of the
lay-up to increase the thickness of the central region 46 of the
part 40 (FIG. 3), while the "spokes" (the strips 56a-56g) are
"fanned" or angularly spaced from each other within each cluster
and with respect to spokes in adjacent clusters. Prior to
curing/molding, the lay-up has a cross-sectional profile that is
similar to the finished part 40 (FIGS. 2-4) except that the lay-up
is flat, that is, the lay-up does not have an overall convex shape.
Thus, in profile, the rear surface of the lay-up has a central
region of increased thickness and gradually tapers to a relatively
thinner peripheral region of substantially uniform thickness
surrounding the central region. In a working embodiment, the lay-up
has a thickness of about 5 mm at the center of the central region
and a thickness of about 3 mm at the peripheral region. A greater
or fewer number of panels and/or clusters of strips can be used to
vary the thickness at the central region and/or peripheral region
of the lay-up.
[0093] To form the lay-up, according to one specific approach,
formation of the panels 52a-52k may be done first by stacking
individual precut, prepreg plies 58a-58d of each panel. After the
panels are formed, the lay-up is built up by laying the second
panel 52b on top of the first panel 52a, and then forming the first
cluster 54a on top of the second panel 52b by laying individual
strips 56a-56g in the prescribed manner. The remaining panels
52c-52k and clusters 54b-54g are then added to the lay-up in the
sequence shown in FIG. 5, followed by the single ply 72. The
fiberglass plies 70, 74 can then be added to the front and back of
the lay-up.
[0094] The fully-formed lay-up can then be subjected to a
"debulking" or compaction step (e.g., using a vacuum table) to
remove and/or reduce air trapped between plies. The lay-up can then
be cured in a mold that is shaped to provide the desired bulge and
roll of the face plate. An exemplary curing process is described in
detail below. Alternatively, any desired bulge and roll of the face
plate may be formed during one or more debulking or compaction
steps performed prior to curing. To form the bulge or roll, the
debulking step can be performed against a die panel having the
final desired bulge and roll. In either case, following curing, the
cured lay-up is removed from the mold and machined to form the part
40.
[0095] The following aspects desirably are controlled to provide
composite components that are capable of withstanding impacts and
fatigue loadings normally encountered by a club-head, especially by
the face plate of the club-head. These three aspects are: (a)
adequate resin content; (b) fiber straightness; and (c) very low
porosity in the finished composite. These aspects can be controlled
by controlling the flow of resin during curing, particularly in a
manner that minimizes entrapment of air in and between the prepreg
layers. Air entrapment is difficult to avoid during laying up of
prepreg layers. However, air entrapment can be substantially
minimized by, according to various embodiments disclosed herein,
imparting a slow, steady flow of resin for a defined length of time
during the laying-up to purge away at least most of the air that
otherwise would become occluded in the lay-up. The resin flow
should be sufficiently slow and steady to retain an adequate amount
of resin in each layer for adequate inter-layer bonding while
preserving the respective orientations of the fibers (at different
respective angles) in the layers. Slow and steady resin flow also
allows the fibers in each ply to remain straight at their
respective orientations, thereby preventing the "wavy fiber"
phenomenon. Generally, a wavy fiber has an orientation that varies
significantly from its naturally projected direction.
[0096] As noted above, the prepreg strips 56 desirably are of
sufficient length such that the fibers in the strips extend
continuously across the part 40; that is, the ends of each fiber
are located at respective locations on the outer peripheral edge 49
of the part 40 (FIGS. 2-4). Similarly, the fibers in the prepreg
panels 52a-52k desirably extend continuously across the part
between respective locations on the outer peripheral edge 49 of the
part. During curing, air bubbles tend to flow along the length of
the fibers toward the outer peripheral (sacrificial) portion of the
lay-up. By making the strips sufficiently long and the panels
larger than the final dimensions of the part 40, the curing process
can be controlled to remove substantially all of the entrapped air
bubbles from the portion of the lay-up that forms the part 40. The
peripheral portion of the lay-up is also where wavy fibers are
likely to be formed. Following curing, the peripheral portion of
the lay-up is removed to provide a net-shape part (or near
net-shape part if further finishing steps are performed) that has a
very low porosity as well as straight fibers in each layer of
prepreg material.
[0097] In working examples, parts have been made without any voids,
or entrapped air, and with a single void in one of the prepreg
plies of the lay-up (either a strip or a panel-size ply). Parts in
which there is a single void having its largest dimension equal to
the thickness of a ply (about 0.1 mm) have a void content, or
porosity, of about 1.7.times.10.sup.-6 percent or less by
volume.
[0098] FIGS. 10A-10C depict an embodiment of a process (pressure
and temperature as functions of time) in which slow and steady
resin flow is performed with minimal resin loss. FIG. 10A shows
temperature of the lay-up as a function of time. The lay-up
temperature is substantially the same as the tool temperature. The
tool is maintained at an initial tool temperature T.sub.i, and the
uncured prepreg lay-up is placed or formed in the tool at an
initial pressure P.sub.1 (typically atmospheric pressure). The tool
and uncured prepreg is then placed in a hot-press at a tool-set
temperature T.sub.s, resulting in an increase in the tool
temperature (and thus the lay-up temperature) until the tool
temperature eventually reaches equilibrium with the set temperature
T.sub.s of the hot-press. As the temperature of the tool increases
from T.sub.i to T.sub.s, the hot-press pressure is kept at P.sub.1
for t=0 to t=t.sub.1. At t=t.sub.1, the hot-press pressure is
ramped from P.sub.1 to P.sub.2 such that, at t=t.sub.2, P=P.sub.2.
Between T.sub.i and T.sub.s, the temperature increase of the tool
and lay-up is continuous. Exemplary rates of change of temperature
and pressure are: .DELTA.T.about.30-60.degree. C./minute up to
t.sub.1, and .DELTA.P.about.50 psi/minute from t.sub.1 to
t.sub.2.
[0099] As the tool temperature increases from T.sub.i to T.sub.s,
the viscosity of the resin first decreases to a minimum, at time
t.sub.1, before the viscosity rises again due to cross-linking of
the resin (FIG. 10B). At time t.sub.1, resin flows relatively
easily. This increased flow poses an increased risk of resin loss,
especially if the pressure in the tool is elevated. Elevated tool
pressure at this stage also causes other undesirable effects such
as a more agitated flow of resin. Hence, tool pressure should be
maintained relatively low at and around t.sub.1 (see FIG. 10C).
After t.sub.1, cross-linking of the resin begins and progresses,
causing a progressive rise in resin viscosity (FIG. 10B), so tool
pressure desirably is gradually increased in the time span from
t.sub.1 to t.sub.2 to allow (and to encourage) adequate and
continued (but nevertheless controlled) resin flow. The rate at
which pressure is increased should be sufficient to reach maximum
pressure P.sub.2 slightly before the end of rapid increase in resin
viscosity. Again, a desired rate of change is .DELTA.P.about.50
psi/minute from t.sub.1 to t.sub.2. At time t.sub.2 the resin
viscosity desirably is approximately 80% of maximum.
[0100] Curing continues after time t.sub.2 and follows a schedule
of relatively constant temperature T.sub.s and constant pressure
P.sub.2. Note that resin viscosity exhibits some continued increase
(typically to approximately 90% of maximum) during this phase of
curing. This curing (also called "pre-cure") ends at time t.sub.3
at which the component is deemed to have sufficient rigidity
(approximately 90% of maximum) and strength for handling and
removal from the tool, although the resin may not yet have reached
a "full-cure" state (at which the resin exhibits maximum
viscosity). A post-processing step typically follows, in which the
components reach a "full cure" in a batch heating mode or other
suitable manner.
[0101] Thus, important parameters of this specific process are: (a)
T.sub.s, the tool-set temperature (or typical resin-cure
temperature), established according to manufacturer's instructions;
(b) T.sub.i, the initial tool temperature, usually set at
approximately 50% of T.sub.s (in .degree. F. or .degree. C.) to
allow an adequate time span (t.sub.2) between T.sub.i and T.sub.s
and to provide manufacturing efficiency; (c) P.sub.1, the initial
pressure that is generally slightly higher than atmospheric
pressure and sufficient to hold the component geometry but not
sufficient to "squeeze" resin out, in the range of 20-50 psig for
example; (d) P.sub.2, the ultimate pressure that is sufficiently
high to ensure dimensional accuracy of components, in the range of
200-300 psig for example; (e) t.sub.1, which is the time at which
the resin exhibits a minimal viscosity, a function of resin
properties and usually determined by experiment, for most resins
generally in the range of 5-10 minutes after first forming the
lay-up; (f) t.sub.2, the time of maximum pressure, also a time
delay from t.sub.1, where resin viscosity increases from minimum to
approximately 80% of a maximum viscosity (i.e., viscosity of fully
cured resin), appears to be related to the moment when the tool
reaches T.sub.s; and (g) t.sub.3, the time at the end of the
pre-cure cycle, at which the components have reached handling
strength and resin viscosity is approximately 90% of its
maximum.
[0102] Many variations of this process also can be designed and may
work equally as well. Specifically, all seven parameters mentioned
above can be expressed in terms of ranges instead of specific
quantities. In this sense, the processing parameters can be
expressed as follows (see FIGS. 11A-11C):
[0103] T.sub.s: recommended resin cure temperature.+-..DELTA.T,
where .DELTA.T=20, 50, 75.degree. F.
[0104] T.sub.i: initial tool temperature (or
T.sub.s/2).+-..DELTA.T.
[0105] P.sub.1: 0-100 psig.+-..DELTA.P, where .DELTA.P=5, 10, 15,
25, 35, 50 psi.
[0106] P.sub.2: 200-500 psig.+-..DELTA.P.
[0107] t.sub.1: t (minimum.+-..DELTA.x viscosity).+-..DELTA.t,
where .DELTA.x=1, 2, 5, 10, 25% and .DELTA.t=1, 2, 5, 10 min.
[0108] t.sub.2: t (80%.+-..DELTA.x maximum
viscosity).+-..DELTA.t.
[0109] t.sub.3: t (90%.+-..DELTA.x maximum
viscosity).+-..DELTA.t.
[0110] After reaching full-cure, the components are subjected to
manufacturing techniques (machining, forming, etc.) that achieve
the specified final dimensions, size, contours, etc., of the
components for use as face plates on club-heads. Conventional CNC
trimming can be used to remove the sacrificial portion of the
fully-cured lay-up (e.g., the portion surrounding line 64 in FIG.
9). However, because the tool applies a lateral cutting force to
the part (against the peripheral edge of the part), it has been
found that such trimming can pull fibers or portions thereof out of
their plies and/or induce horizontal cracks on the peripheral edge
of the part. These defects can cause premature delamination or
other failure.
[0111] In certain embodiments, the sacrificial portion of the
fully-cured lay-up is removed by water-jet cutting. In water-jet
cutting, the cutting force is applied in a direction perpendicular
to the prepreg plies (in a direction normal to the front and rear
surfaces of the lay-up), which minimizes the occurrence of cracking
and fiber pull out. Consequently, water-jet cutting can be used to
increase the overall durability of the part.
[0112] The potential mass "savings" obtained from fabricating at
least a portion of the face plate of composite, as described above,
is about 10-30 g, or more, relative to a 2.7-mm thick face plate
formed from a titanium alloy such as Ti-6Al-4V, for example. In a
specific example, a mass savings of about 15 g relative to a 2.7-mm
thick face plate formed from a titanium alloy such as Ti-6Al-4V can
be realized. As mentioned above, this mass can be allocated to
other areas of the club, as desired.
[0113] FIG. 12 shows a portion of a simplified lay-up 78 that can
be used to form the composite part 40 (FIGS. 2-4). The lay-up 78 in
this example can include multiple prepreg panels (e.g., panels
52a-52k) and one or more clusters 80 of prepreg strips 82. The
illustrated cluster 80 comprises only four strips 82 of equal width
arranged in a criss-cross pattern and which are equally angularly
spaced or fanned with respect to each other about the center of the
cluster. Although the figure shows only one cluster 80, the lay-up
desirably includes multiple clusters 80 (e.g., 1 to 12 clusters,
with 7 clusters in a specific embodiment). Each cluster is rotated
or angularly offset with respect to an adjacent cluster to provide
an angular offset between strips of one cluster with the strips of
an adjacent cluster, such as described above, in order to form the
reduced-thickness peripheral portion of the lay-up.
[0114] The embodiments described thus far provide a face plate
having a projection or cone at the sweet spot. However, various
other cross-sectional profiles can be achieved by selective
placement of prepreg strips in the lay-up. FIGS. 13-15, for
example, show a composite component 90 for use as a face plate for
a club-head (either by itself or in combination with a polymeric or
metal outer layer). The composite component 90 has a front surface
92, a rear surface 94, and an overall slightly convex shape. The
reverse surface 94 defines a point 96 situated in a central recess
98. The point 96 represents the approximate center of the sweet
spot of the face plate, not necessarily the center of the face
plate, and is located in the approximate center of the recess 98.
The central recess 98 is a "dimple" having a spherical or otherwise
radiused sectional profile in this embodiment (see FIGS. 14 and
15), and is surrounded by an annular ridge 100. At the point 96 the
thickness of the component 90 is less than at the "top" 102 of the
annular ridge 100. The top 102 is normally the thickest portion of
the component. Outward from the top 102, the thickness of the
component gradually decreases to form a peripheral region 104 of
substantially uniform thickness surrounding the ridge 100. Hence,
the central recess 98 and surrounding ridge 100 have a
cross-sectional profile that is reminiscent of a "volcano."
Generally speaking, an advantage of this profile is that thinner
central region is effective to provide a larger sweet spot, and
therefore a more forgiving club-head.
[0115] FIG. 16 is a plan view of a lay-up 110 of multiple prepreg
plies that can be used to fabricate the composite component 90.
FIG. 17 shows an exploded view of a few of the prepreg layers that
form the lay-up 110. As shown, the lay-up 110 includes multiple
panels 112a, 112b, 112c of prepreg material and sets, or clusters,
114a, 114b, 114c of prepreg strips interspersed between the panels.
The panels 112a-112c can be formed from one or more prepreg plies
and desirably comprise four plies having respective fibers
orientations of +45 degrees, 0 degrees, -45 degrees, and 90
degrees, in the manner described above. The line 118 in FIGS. 16
and 17 represent the outline of the composite component 90 and the
portion surrounding the line 118 is a sacrificial portion. Once the
lay-up 110 is cured, the sacrificial portion surrounding the line
118 can be removed to form the component 90.
[0116] Each cluster 114a-114c in this embodiment comprises four
criss-cross strips 116 arranged in a specific shape. In the
illustrated embodiment, the strips of the first cluster 114a are
arranged to form a parallelogram centered on the center of the
panel 112a. The strips of the second cluster 114b also are arranged
to form a parallelogram centered on the center of the panel 112b
and rotated 90 degrees with respect to the first cluster 114a. The
strips of the third cluster 114c are arranged to form a rectangle
centered on the center of panel 112c. When stacked in the lay-up,
as best shown in FIG. 16, the strips 116 of clusters 114a-114c
overlay one another so as to collectively form an oblong, annular
area of increased thickness corresponding to the annular ridge 100
(FIG. 14). Hence, the fully-formed lay-up has a rear surface having
a central recess and a surrounding annular ridge of increased
thickness formed collectively by the build up of strip clusters
114a-114c. Additional panels 112a-112c and strip clusters 114a-114c
may be added to lay-up to achieve a desired thickness profile.
[0117] It can be appreciated that the number of strips in each
cluster can vary and still form the same profile. For example, in
another embodiment, clusters 114a-114c can be stacked immediately
adjacent each other between adjacent panels 112 (i.e., effectively
forming one cluster of twelve strips 116).
[0118] The lay-up 110 may be cured and shaped to remove the
sacrificial portion of the lay-up (the portion surrounding the line
118 in FIG. 16 representing the finished part), as described above,
to form a net shape part. As in the previous embodiments, each
strip 116 is of sufficient length to extend continuously across the
part 90 so that the free ends of the fibers are located on the
peripheral edge of the part. In this manner, the net shape part can
be formed free of any voids, or with an extremely low void content
(e.g., about 1.7.times.10.sup.-6 percent or less by volume) and can
have straight fibers in each layer of prepreg material.
[0119] As mentioned above, any of various cross-sectional profiles
can be achieved by arranging strips of prepreg material in a
predetermined manner. Examples of other face plate profiles that
can be formed by the techniques described herein are disclosed in
U.S. Pat. Nos. 6,800,038, 6,824,475, 6,904,663, and 7,066,832, all
of which are incorporated herein by reference.
[0120] As mentioned above, the face plate 12 (FIG. 1) can include a
composite plate and a metal cap covering the front surface of the
composite plate. One such embodiment is shown, for example, in the
partial section depicted in FIG. 18, in which the face plate 12
comprises a metal "cap" 130 formed or placed over a composite plate
40 to form the strike surface 13. The cap 130 includes a peripheral
rim 132 that covers the peripheral edge 134 of the composite plate
40. The rim 132 can be continuous or discontinuous, the latter
comprising multiple segments (not shown).
[0121] The metal cap 130 desirably is bonded to the composite plate
40 using a suitable adhesive 136, such as an epoxy, polyurethane,
or film adhesive. The adhesive 136 is applied so as to fill the gap
completely between the cap 130 and the composite plate 40 (this gap
usually in the range of about 0.05-0.2 mm, and desirably is
approximately 0.1 mm). The face plate 12 desirably is bonded to the
body 14 using a suitable adhesive 138, such as an epoxy adhesive,
which completely fills the gap between the rim 132 and the adjacent
peripheral surface 140 of the face support 18 and the gap between
the rear surface of the composite plate 40 and the adjacent
peripheral surface 142 of the face support 18.
[0122] A particularly desirable metal for the cap 130 is titanium
alloy, such as the particular alloy used for fabricating the body
(e.g., Ti-6Al-4V). For a cap 130 made of titanium alloy, the
thickness of the titanium desirably is less than about 1 mm, and
more desirably less than about 0.3 mm. The candidate titanium
alloys are not limited to Ti-6Al-4V, and the base metal of the
alloy is not limited to Ti. Other materials or Ti alloys can be
employed as desired. Examples include commercially pure (CP) grade
Ti, aluminum and aluminum alloys, magnesium and magnesium alloys,
and steel alloys.
[0123] Surface roughness can be imparted to the composite plate 40
(notably to any surface thereof that will be adhesively bonded to
the body of the club-head and/or to the metal cap 130). In a first
approach, a layer of textured film is placed on the composite plate
40 before curing the film (e.g., "top" and/or "bottom" layers
discussed above). An example of such a textured film is ordinary
nylon fabric. Conditions under which the adhesives 136, 138 are
cured normally do not degrade nylon fabric, so the nylon fabric is
easily used for imprinting the surface topography of the nylon
fabric to the surface of the composite plate. By imparting such
surface roughness, adhesion of urethane or epoxy adhesive, such as
3M.RTM. DP 460, to the surface of the composite plate so treated is
improved compared to adhesion to a metallic surface, such as cast
titanium alloy.
[0124] In a second approach, texture can be incorporated into the
surface of the tool used for forming the composite plate 40,
thereby allowing the textured area to be controlled precisely and
automatically. For example, in an embodiment having a composite
plate joined to a cast body, texture can be located on surfaces
where shear and peel are dominant modes of failure.
[0125] FIG. 19 shows an embodiment similar to that shown in FIG.
18, with one difference being that in the embodiment of FIG. 19,
the face plate 12 includes a polymeric outer layer, or cap, 150 on
the front surface of the composite plate 40 forming the striking
surface 13. The outer layer 150 desirably completely covers at
least the entire front surface of the composite plate 40. A list of
suitable polymers that can be used as an outer layer on a face
plate is provide below. A particularly desirable polymer is
urethane. For an outer layer 150 made of urethane, the thickness of
the layer desirably is in the range of about 0.2 mm to about 1.2
mm, with about 0.4 mm being a specific example. As shown, the face
plate 12 can be adhesively secured to the face support 18 by an
adhesive 138 that completely fills the gap between the peripheral
edge 134 and the adjacent peripheral surface 140 of the face
support 18 and the gap between the rear surface of the composite
plate 40 and the adjacent peripheral surface 142 of the face
support 18.
[0126] The composite face plate as described above need not be
coextensive (dimensions, area, and shape) with a typical face plate
on a conventional club-head. Alternatively, a subject composite
face plate can be a portion of a full-sized face plate, such as the
area of the "sweet spot." Both such composite face plates are
generally termed "face plates" herein. Further, the composite plate
40 itself (without additional layers of material bonded or formed
on the composite plate) can be used as the face plate 12.
Example 1
[0127] In this example, a number of composite strike plates were
formed using the strip approach described above in connection with
FIGS. 2-9. A number of strike plates having a similar profile were
formed using the partial ply approach described above. Five plates
of each batch were sectioned and optically examined for voids.
Table 1 below reports the yield of the examined parts. The yield is
the percentage of parts made that did not contain any voids. As can
be seen, the strip approach provided a much greater yield of parts
without voids than the partial ply approach. The remaining parts of
each batch were then subjected to endurance testing during which
the parts were subjected to 3600 impacts at a ball speed of 50 m/s.
As shown in Table 1, the parts made by the strip approach yielded a
much higher percentage of parts that survived 3600 impacts than the
parts made by the partial ply approach (72.73% vs. 52%). Table 1
also shows the average characteristic time (CT) (ball contact time
with the strike plate) measured during the endurance test.
TABLE-US-00001 TABLE 1 Number Average of % of weight Yield CT
Pieces passing passing Maximum (g) (%) (.mu.s) tested parts parts
shots Strip 21.9 81 255 11 8 72.73 3600 Partial 21.6 57.5 259 25 13
52 3600 ply
Example 2
[0128] In this example, a number of composite strike plates were
formed using the strip approach described above in connection with
FIGS. 2-9. A number of strike plates having a similar profile were
formed using the partial ply approach above. Five plates of each
batch were sectioned and optically examined for voids. Table 2
below reports the yield of the parts formed by both methods. As in
Example 1, the strip approach provided a much greater yield of
parts without voids than the partial ply approach (90% vs. 70%).
The remaining parts of each batch were then subjected to endurance
testing during which the parts were subjected to 3600 impacts at a
ball speed of 42 m/s. At this lower speed, all of the tested parts
survived 3600 impacts.
TABLE-US-00002 TABLE 2 Number Average of % of weight Yield CT
Pieces passing passing Maximum (g) (%) (.mu.s) tested parts parts
shots Strip 22 90 255 11 11 100 3600 Partial 21.5 70 258 16 16 100
3600 ply
[0129] The methods described above provide improved structural
integrity of the face plates and other club-head components
manufactured according to the methods, compared to composite
component manufactured by prior-art methods. These methods can be
used to fabricate face plates for any of various types of clubs,
such as (but not limited to) irons, wedges, putter, fairway woods,
etc., with little to no process-parameter changes.
[0130] The subject methods are especially advantageous for
manufacturing face plates because face plates are the most severely
loaded components in golf club-heads. If desired, conventional (and
generally less expensive) composite-processing techniques (e.g.,
bladder-molding, etc.) can be used to make other parts of a
club-head not subject to such severe loads.
[0131] Moreover, the methods for fabricating composite parts
described herein can be used to make various other types of
composite parts, and in particular, parts that are subject to high
impact loads and/or repetitive loads. Some examples of such parts
include, without limitation, a hockey stick (e.g., the blade of a
stick), a bicycle frame, a baseball bat, and a tennis racket, to
name a few.
Example 3
[0132] As shown in FIGS. 18-19, a metallic cover can be provided so
that a golf club striking plate includes a composite face plate and
a metallic striking surface that tends to be wear resistant. A
representative metallic cover 160 is illustrated in detail in FIGS.
20-23. Referring to FIG. 20, the metallic cover 160 provides a
striking surface 161 that includes a central striking region 162
and a plurality of contrasting scorelines 164a-164j that are
associated with respective dents, depressions, or indentations in
the metallic cover that are generally filled with a contrasting
pigment or paint such as white paint. Scorelines generally extend
along an axis parallel to a toe-to-heel direction. In a
representative example, scorelines have lengths of between about 6
mm and 14 mm, with scoreline lengths larger toward a golf club
crown. The scorelines are spaced about 6-7 mm apart in a
top-to-bottom direction. The arrangement of FIG. 20 is one example,
and other arrangements can be used.
[0133] The metallic cover 160 is generally made of a titanium alloy
or other metal such as those mentioned above, and has a bulge/roll
center 166 for bulge and roll curvatures that are provided to
control club performance. Centers of curvature for bulge/roll
curvatures are typically situated on an axis that is perpendicular
to the striking surface 161 at the bulge/roll center 166. In this
example, innermost edges of the scorelines 164a-164j are situated
along a circumference of a circle having a diameter of about 40-50
mm that is centered at the bulge/roll center 166. As shown in the
sectional view of FIG. 21, a "roll" radius of curvature (a
top-to-bottom radius of curvature) is about 300 mm and is symmetric
about the bulge/roll center. As shown in the sectional view of FIG.
22, a "bulge" radius of curvature (a toe-to-heel radius of
curvature) is about 410 mm and is symmetric about the bulge/roll
center 166. Bulge and roll curvatures can be spherical or circular
curvatures, but other curvatures such as elliptical, oval, or other
curvatures can be provided. In this example, a rim 168 is provided
and is intended to at least partially cover an edge of a composite
faceplate to which the metallic cover 160 is attached.
[0134] The striking region 162 can be roughened by sandblasting,
bead blasting, sanding, or other abrasive process or by a machining
or other process. The scorelines 164a-164j are situated outside of
the intended striking region 162 and are generally provided for
visual alignment and do not typically contribute to ball
trajectory. A cross-section of a representative scoreline 164a is
shown in FIG. 23 (paint or other pigment is not shown). The
scoreline 164a is provided as an indentation in the cover 160 and
includes transition portions 170, 174 and a bottom portion 172. For
a thin cover plate (thickness less than about 1.0 mm, 0.5 mm, 0.3
mm, or 0.2 mm), the scoreline 164a can be formed by pressing a
correspondingly shaped tool against a sheet of a selected cover
plate material. An overall curvature for the cover 160 can also be
provided in the same manner based on a bulge and roll of a face
plate such as a composite face plate to which the cover 160 is to
be applied. For a typical cover thickness, indented scorelines are
associated with corresponding protruding features on a rear surface
176 of the cover 160. In this example, the scoreline 164a has a
depth D of about 0.07 mm in a cover having a thickness T of about
0.30 mm. A width W.sub.B of the bottom portion 172 is about 0.29
mm, and a width W.sub.G of the entire indent is about 0.90 mm. The
transition portions 170, 174 have inner and outer radiused regions
181, 185 and 180, 184, respectively, having respective radii of
curvature of about 0.40 mm and 0.30 mm.
[0135] In other examples, a cover can be between about 0.10 mm and
1.0 mm thick, between about 0.2 mm and 0.8 mm thick, or between
about 0.3 mm and 0.5 mm thick. Indentation depths between about
0.02 mm and 0.12 mm or about 0.06 mm and 0.10 mm are generally
preferred for scoreline definition. Impact resistant cover plates
with scorelines generally have scoreline depths D and cover plate
thicknesses T such that a ratio D/T is less than about 0.4, 0.3,
0.25, or 0.20. A ratio W.sub.B/T is typically between about 0.5 and
1.5, 0.75 and 1.25, or 0.9 and 1.1. A ratio W.sub.G/T is typically
between about 1 and 5, 2 and 4, or 2.5 and 3.5. A ratio of
transition region radii of curvature R to cover thickness T is
typically between about 0.5 and 1.5, 0.67 and 1.33, or 0.75 and
1.33. While it is convenient to provide scorelines based on common
indentation depths, scorelines on a single cover can be based on
indentations of one or more depths.
[0136] For wood-type golf clubs, an impact area is based on areas
associated with inserts used in traditional wood golf clubs. For
irons, an impact area is a portion of the striking surface within
20 mm on either side of a vertical centerline, but does not include
6.35 mm wide strips at the top and bottom of the striking surface.
For wood-type golf clubs, scorelines are generally provided in a
cover so as to be situated exterior to an impact region. The
disclosed covers with scorelines are sufficiently robust for
placement within or without an impact region for either wood or
iron type golf clubs.
[0137] A cover is generally formed from a sheet of cover stock that
is processed so as to have a bulge/roll region that includes the
necessary arrangement of scoreline dents. The formed cover stock is
then trimmed to fit an intended face plate, and attached to the
face plate with an adhesive. Typically a glue layer is situated
between the cover and the face plate, and the cover and face plate
are urged together so as to form an adhesive layer of a suitable
thickness. For typical adhesives, layer thicknesses between about
0.05 mm and 0.10 mm are preferred. Once a suitable layer thickness
is achieved, the adhesive can be cured or allowed to set. In some
cases, the cover includes a cover lip or rim as well so as to cover
a face plate perimeter. The scoreline indentations are generally
filled with paint of a color that contrasts with the remainder of
the striking surface.
[0138] Although the scorelines are provided to realize a particular
appearance in a finished product, the indentations used to define
the scorelines also serve to control adhesive thickness. As a cover
plate and a face plate are urged together in a gluing operation,
the rear surface protrusions associated with the indentations tend
to approach the face plate and thus regulate an adhesive layer
thickness. Accordingly, indentation depth can be selected not only
to retain paint or other pigment on a striking face, but can also
based on a preferred adhesive layer thickness. In some examples,
protruding features of indentations in a cover plate are situated
at distances of less than about 0.10 mm, 0.05 mm, 0.03 mm, and 0.01
mm from a face plate surface as an adhesive layer thickness is
established.
[0139] In other examples, the indent-based scorelines shown in
FIGS. 20-23 can be replaced with grooves that are punched,
machined, etched or otherwise formed in a cover plate sheet.
Indentations are generally preferable as gluing operations based on
indented plates are not generally associated with adhesive transfer
to the striking surface. In addition, striking plates made with
dented metallic covers tend to be more stable in long term use than
cover plates that have been machined or punched. Scoreline or
indent dimensions (length, depth, and transition region dimensions
and curvatures) as well as scoreline or indentation location on a
striking surface are preferably selected based on a selected cover
material or cover material thickness. Fabrication methods (such as
punching, machining) tend to produce cover plates that are more
likely to show wear under impact endurance testing in which a
finished striking plate is subject to the forces associated with
3000 shots by, for example, forming a club head with a striking
plate under test, and making 3000 shots with the club head. A cover
that performs successfully under such testing without degradation
is referred as an impact-resistant cover plate.
[0140] In alternative embodiments, a cover includes a plurality of
slots situated around a striking region. A suitably colored
adhesive can be used to secure the cover layer to a face plate so
that the adhesive fills the slots or is visible through the slots
so to provide visible orientation guides on the striking plate
surface.
Example 4
[0141] Polymer or other surface coatings or surface layers can be
provided to composite or other face plates to provide performance
similar to that of conventional irons and metal type woods. Such
surface layers, methods of forming such layers, and
characterization parameters for such layers are described
below.
Surface Texture and Roughness
[0142] Surface textures or roughness can be conveniently
characterized based a surface profile, i.e., a surface height as a
function of position on the surface. A surface profile is typically
obtained by interrogating a sample surface with a stylus that is
translated across the surface. Deviations of the stylus as a
function of position are recorded to produce the surface profile.
In other examples, a surface profile can be obtained based on other
contact or non-contact measurements such as with optical
measurements. Surface profiles obtained in this way are often
referred to as "raw" profiles. Alternatively, surface profiles for
a golf club striking surface can be functionally assessed based on
shot characteristics produced when struck with surfaces under wet
conditions.
[0143] For convenience, a control layer is defined as a striking
face cover layer configured so that shots are consistent under wet
and dry playing conditions. Generally, satisfactory roughened or
textured striking surfaces (or other control surfaces) provide ball
spins of at least about 2000 rpm, 2500 rpm, 3000 rpm, or 3500 rpm
under wet conditions when struck with club head speeds of between
about 75 mph and 120 mph. Such control surfaces thus provide shot
characteristics that are substantially the same as those obtained
with conventional metal woods. Stylus or other measurement based
surface roughness characterizations for such control surfaces are
described in detail below.
[0144] A surface profile is generally processed to remove gradual
deviations of the surface from flatness. For example, a wood-type
golf club striking face generally has slight curvatures from
toe-to-heel and crown-to-sole to improve ball trajectory, and a
"raw" surface profile of a striking surface or a cover layer on the
striking surface can be processed to remove contributions
associated with these curvatures. Other slow (i.e., low spatial
frequency) contributions can also be removed by such processing.
Typically features of size of about 1 mm or greater (or spatial
frequencies less than about 1/mm) can be removed by processing as
the contributions of these features to ball spin about a horizontal
or other axis tend to be relatively small. A raw (unprocessed)
profile can be spatially filtered to enhance or suppress high or
low spatial frequencies. Such filtering can be required in some
measurements to conform to various standards such as DIN or other
standards. This filtering can be performed using processors
configured to execute a Fast Fourier Transform (FFT).
[0145] Generally, a patterned roughness or texture is applied to a
substantial portion of a striking surface or at least to an impact
area. For wood-type golf clubs, an impact area is based on areas
associated with inserts used in traditional wood golf clubs. For
irons, an impact area is a portion of the striking surface within
20 mm on either side of a vertical centerline, but does not include
6.35 mm wide strips at the top and bottom of the striking surface.
Generally, such patterned roughness need not extend across the
entire striking surface and can be provided only in a central
region that does not extend to a striking surface perimeter.
Typically for hollow metal woods, at least some portions of the
striking surface at the striking surface perimeter lack pattern
roughness in order to provide an area suitable for attachment of
the striking plate to the head body.
[0146] Striking surface roughness can be characterized based on a
variety of parameters. A surface profile is obtained over a
sampling length of the striking surface and surface curvatures
removed as noted above. An arithmetic mean R.sub.a is defined a
mean value of absolute values of profile deviations from a mean
line over a sampling length of the surface. For a surface profile
over the sampling length that includes N surface samples each of
which is associated with a mean value of deviations Y.sub.i, from
the mean line, the arithmetic mean R.sub.a is:
R a = 1 N i = 1 N Y i , ##EQU00001##
wherein i is an integer i=1, . . . , N. The sampling length
generally extends along a line on the striking surface over a
substantial portion or all of the striking area, but smaller
samples can be used, especially for a patterned roughness that has
substantially constant properties over various sample lengths.
Two-dimensional surface profiles can be similarly used, but one
dimensional profiles are generally satisfactory and convenient. For
convenience, this arithmetic mean is referred to herein as a mean
surface roughness.
[0147] A surface profile can also be further characterized based on
a reciprocal of a mean width S.sub.m of the profile elements. This
parameter is used and described in one or more standards set forth
by, for example, the German Institute for Standardization (DIN) or
the International Standards Organization (ISO). In order to
establish a value for S.sub.m, an upper count level (an upward
surface deviation associated with a peak) and a lower count level
(a downward surface deviation associated with a valley) are
defined. Typically, the upper count level and the lower count level
are defined as values that are 5% greater than the mean line and 5%
less than the mean line, but other count levels can be used. A
portion of a surface profile projecting upward over the upper count
level is called a profile peak, and a portion projecting downward
below the given lower count level is called a profile valley. A
width of a profile element is a length of the segment intersecting
with a profile peak and the adjacent profile valley. S.sub.m is a
mean of profile element widths S.sub.mi within a sampling
length:
S m = 1 K i = 1 K S mi ##EQU00002##
For convenience, this mean is referred to herein as a mean surface
feature width.
[0148] In determining S.sub.m, the following conditions are
generally satisfied: 1) Peaks and valleys appear alternately; 2) An
intersection of the profile with the mean line immediately before a
profile element is the start point of a current profile element and
is the end point of a previous profile element; and 3) At the start
point of the sampling length, if either of the profile peak or
profile valley is missing, the profile element width is not taken
into account. Rpc is defined as a reciprocal of the mean width
S.sub.m and is referred to herein as mean surface feature
frequency.
[0149] Another surface profile characteristic is a surface profile
kurtosis Ku that is associated with an extent to which profile
samples are concentrated near the mean line. As used herein, a the
profile kurtosis Ku is defined as:
Ku = 1 R q 4 1 N i = 1 N ( Y i ) 4 , ##EQU00003##
wherein R.sub.q a square root of the arithmetic mean of the squares
of the profile deviations from the mean line, i.e.,
R q = ( 1 N i = 1 N Y i 2 ) 1 / 2 . ##EQU00004##
[0150] Profile kurtosis is associated with an extent to which
surface features are pointed or sharp. For example, a triangular
wave shaped surface profile has a kurtosis of about 0.79, a
sinusoidal surface profile has a kurtosis of about 1.5, and a
square wave surface profile has a kurtosis of about 1.
[0151] Other parameters that can be used to characterize surface
roughness include R.sub.z which is based on a sum of a mean of a
selected number of heights of the highest peaks and a mean of a
corresponding number of depths of the lowest valleys.
[0152] One or more values or ranges of values can be specified for
surface kurtosis Ku, mean surface feature width S.sub.m, and
arithmetic mean deviation R.sub.a (mean surface roughness) for a
particular golf club striking surface. Superior results are
generally obtained with R.sub.a.ltoreq.5 .mu.m,
R.sub.pc.gtoreq.30/cm, and K.sub.u.gtoreq.2.0.
Wood-Type Club Heads
[0153] For convenient illustration, representative examples of
striking plates and cover layers for such striking plates are set
forth below with reference to wood-type golf clubs. In other
examples, such striking plates can be used in iron-type golf clubs.
In some examples, face plate cover layers are formed on a surface
of a face plate in a molding process, but in other examples surface
layers are provided as caps that are formed and then secured to a
face plate.
[0154] As illustrated in FIGS. 24-27, a typical wood type (i.e.,
driver or fairway wood) golf club head 205 includes a hollow body
210 delineated by a crown 215, a sole 220, a skirt 225, a striking
plate 230, and a hosel 235. The striking plate 230 defines a front
surface, or striking face 240 adapted for impacting a golf ball
(not shown). The hosel 235 defines a hosel bore 237 adapted to
receive a golf club shaft (not shown). The body 210 further
includes a heel portion 245, a toe portion 250 and a rear portion
255. The crown 215 is defined as an upper portion of the club head
5 extending above a peripheral outline 257 of the club head as
viewed from a top-down direction and rearwards of the topmost
portion of the striking face 240. The sole 220 is defined as a
lower portion of the club head 205 extending in an upwardly
direction from a lowest point of the club head approximately 50% to
60% of the distance from the lowest point of the club head to the
crown 215. The skirt 225 is defined as a side portion of the club
head 205 between the crown 215 and the sole 220 extending
immediately below the peripheral outline 257 of the club head,
excluding the striking face 240, from the toe portion 250, around
the rear portion 255, to the heel portion 245. The club head 205
has a volume, typically measured in cubic-centimeters (cm.sup.3),
equal to the volumetric displacement of the club head 205.
[0155] Referencing FIGS. 28-29, club head coordinate axes can be
defined with respect to a club head center-of-gravity (CG) 280. A
CG.sub.z-axis 285 extends through the CG 280 in a generally
vertical direction relative to the ground 299 when the club head
205 is at address position. A CG.sub.x-axis 290 extends through the
CG 280 in a heel-to-toe direction generally parallel to the
striking face 240 and generally perpendicular to the CG.sub.z-axis
285. A CG.sub.y-axis 95 extends through the CG 280 in a
front-to-back direction and generally perpendicular to the
CG.sub.x-axis 290 and the CG.sub.z-axis 285. The CG.sub.x-axis 290
and the CG.sub.y-axis 295 both extend in a generally horizontal
direction relative to the ground when the club head 5 is at address
position. The polymer coated or capped striking plates described
herein generally provide 2-15 g of additional distributable mass so
that placement of the CG 280 can be selected using this mass.
[0156] A club head origin coordinate system can also be used.
Referencing FIGS. 30-31, a club head origin 260 is represented on
club head 205. The club head origin 260 is positioned at an
approximate geometric center of the striking face 240 (i.e., the
intersection of the midpoints of the striking face's height and
width, as defined by the USGA "Procedure for Measuring the
Flexibility of a Golf Clubhead," Revision 2.0).
[0157] The head origin coordinate system, with head origin 260,
includes three axes: a z-axis 265 extending through the head origin
260 in a generally vertical direction relative to the ground 100
when the club head 205 is at address position; an x-axis 270
extending through the head origin 60 in a heel-to-toe direction
generally parallel to the striking face 240 and generally
perpendicular to the z-axis 265; and a y-axis 275 extending through
the head origin 260 in a front-to-back direction and generally
perpendicular to the x-axis 270 and the z-axis 265. The x-axis 270
and the y-axis 275 both extend in a generally horizontal direction
relative to the ground 299 when the club head 205 is at address
position. The x-axis 270 extends in a positive direction from the
origin 260 to the toe 250 of the club head 205; the y-axis 275
extends in a positive direction from the origin 260 towards the
rear portion 255 of the club head 205; and the z-axis 265 extends
in a positive direction from the origin 260 towards the crown
215.
[0158] In a club-head according to one embodiment, a striking plate
includes a face plate and a cover layer. In addition, in some
examples, at least a portion of the face plate is made of a
composite including multiple plies or layers of a fibrous material
(e.g., graphite, or carbon, fiber) embedded in a cured resin (e.g.,
epoxy). Examples of suitable polymers that can be used to form the
cover layer include, without limitation, urethane, nylon, SURLYN
ionomers, or other thermoset, thermoplastic, or other materials.
The cover layer defines a striking surface that is generally a
patterned, roughened, and/or textured surface as described in
detail below. Striking plates based on composites typically permit
a mass reduction of between about 5 g and 20 g in comparison with
metal striking plates so that this mass can be redistributed.
[0159] In the example shown in FIGS. 32-34, a striking plate 380
includes a face plate 381 fabricated from a plurality of prepreg
plies or layers and has a desired shape and size for use in a
club-head. The face plate 381 has a front surface 382 and a rear
surface 344. In this example, the face plate 381 has a slightly
convex shape, a central region 346 of increased thickness, and a
peripheral region 348 having a relatively reduced thickness
extending around the central region 346. The central region 346 in
the illustrated example is in the form of a projection or cone on
the rear surface having its thickest portion at a central point 350
and gradually tapering away from the point in all directions toward
the peripheral region 348. The central point 350 represents the
approximate center of the "sweet spot" (optimal strike zone) of the
striking plate 380, but not necessarily the geometric center of the
face plate 381. The thicker central region 348 adds rigidity to the
central area of the face plate 381, which effectively provides a
more consistent deflection across the face plate. In certain
embodiments, the face plate 381 is fabricated by first forming an
oversized a lay-up of multiple prepreg plies that are subsequently
trimmed or otherwise machined.
[0160] As shown in FIGS. 33-34, a cover layer 360 is situated on
the front surface 382 of the face plate 381. The cover layer 360
includes a rear surface 362 that is typically conformal with and
bonded to the front surface 382 of the face plate 381, and a
striking surface 364 that is typically provided with patterned
roughness so as to control or select a shot characteristic so as to
provide performance similar to that obtained with conventional club
construction. The cover layer 360 can be formed of a variety of
polymers such as, for example, SURLYN ionomers, urethanes, or
others. Representative polymers are disclosed in U.S. patent
application Ser. Nos. 11/685,335, filed Mar. 13, 2007 and
11/809,432, filed May 31, 2007 that are incorporated herein by
reference. These polymers are discussed with reference to golf
balls, but are also suitable for use in striking plates as
described herein. In some examples, the cover layer 360 can be
co-cured with the prepreg layers that form the face plate 381. In
other examples, the cover layer 360 is formed separately and then
bonded or glued to the face plate 381. The cover layer 362 can be
selected to provide wear resistance or ultraviolet protection for
the face plate 381, or to include a patterned striking surface that
provides consistent shot characteristics during play in both wet
and dry conditions. Typically, surface textures and/or patterning
are configured so as to substantially duplicate the shot
characteristics achieved with conventional wood clubs or metal wood
type clubs with metallic striking plates. To enhance wear
resistance, a Shore D hardness of the cover layer 360 is preferably
sufficient to provide a striking face effective hardness with the
polymer layer applied of at least about 75, 80, or 85. In typical
examples, a thickness of the cover layer 360 is between about 0.1
mm and 3.0 mm, 0.15 mm and 2.0 mm, or 0.2 mm and 1.2 mm. In some
examples, the cover layer 360 is about 0.4 mm thick.
[0161] Club face hardness or striking face hardness is generally
measured based on a force required to produce a predetermined
penetration of a probe of a standard size and/or shape in a
selected time into a striking face of the club, or a penetration
depth associated with a predetermined force applied to the probe.
Based on such measurements, an effective Shore D hardness can be
estimated. For the club faces described herein, the Shore D
hardness scale is convenient, and effective Shore D hardnesses of
between about 75 and 90 are generally obtained. In general,
measured Shore D values decrease for longer probe exposures. Club
face hardnesses as described herein are generally based on probe
penetrations sufficient to produce an effective hardness estimate
(an effective Shore D value) that can be associated with shot
characteristics substantially similar to conventional wood or metal
wood type golf clubs. The effective hardness generally depends on
faceplate and polymer layer thicknesses and hardnesses.
[0162] As shown in FIG. 35, a striking plate 312 comprises a cover
layer 330 formed or placed over a composite face plate 340 to form
a striking surface 313. In other examples, the cover layer 330 can
include a peripheral rim that covers a peripheral edge 334 of the
composite face plate 340. The rim 332 can be continuous or
discontinuous, the latter comprising multiple segments (not shown).
The cover layer 330 can be bonded to the composite plate 340 using
a suitable adhesive 336, such as an epoxy, polyurethane, or film
adhesive, or otherwise secured. The adhesive 336 is applied so as
to fill the gap completely between the cover layer 330 and the
composite plate 340 (this gap is usually in the range of about
0.05-0.2 mm, and desirably is less than approximately 0.05 mm).
Typically the cover layer 330 is formed directly on the face plate,
and the adhesive 336 is omitted. The striking plate 312 desirably
is bonded to a club body 314 using a suitable adhesive 338, such as
an epoxy adhesive, which completely fills the gap between the rim
332 and the adjacent peripheral surface 338 of the face support 318
and the gap between the rear surface of the composite plate 340 and
the adjacent peripheral surface 342 of the face support 318. In the
example of FIG. 35, the cover layer 330 extends at least partially
around a faceplate edge, but in other examples, a cover layer is
situated only on an external surface of the face plate. As used
herein, an external surface of a face plate is a face plate surface
directed towards a ball in normal address position. In conventional
metallic striking plates that consist only of a metallic face
plate, the external surface is the striking surface.
[0163] Cover layers such as the cover layer 330 can be formed and
secured to a face plate using various methods. In one example, a
striking surface of a cover layer is patterned with a mold. A
selected roughness pattern is etched, machined, or otherwise
transferred to a mold surface. The mold surface is then used to
shape the striking surface of the cover layer for subsequent
attachment to a composite face plate or other face plate. Such
cover layers can be bonded with an adhesive to the face plate.
Alternatively, the mold can be used to form the cover layer
directly on the composite part. For example, a layer of a
thermoplastic material (or pellets or other portions of such a
material) can be situated on an external surface of a face plate,
and the mold pressed against the thermoplastic material and the
face plate at suitable temperatures and pressures so as to impress
the roughness pattern on a thermoplastic layer, thereby forming a
cover layer with a patterned surface. In another example, a
thermoset material can be deposited on the external surface of the
cover plate, and the mold pressed against the thermoset material
and the face plate to provide a suitable cover layer thickness. The
face plate, the thermoset material, and the mold are then raised to
a suitable temperature so as to cure or otherwise fix the shape and
thickness of the cover layer. These methods are examples only, and
other methods can be used as may be convenient for various cover
materials.
[0164] In another method, a layer of a so-called "peel ply" fabric
is bonded to an exterior surface of a composite face plate
(preferably as the face plate is fabricated) or to a striking
surface on a polymer cover layer. In some examples, a thermoset
material is used for the cover layer, while in other examples
thermoplastic materials are used. With either type of material, the
peel ply fabric is removably bonded to the cover layer (or to the
face plate). The peel ply fabric is removed from the cover layer,
leaving a textured or roughened striking surface. A striking
surface texture can be selected based upon peel ply fabric texture,
fabric orientation, and fiber size so as to achieve surface
characteristics comparable to conventional metal woods and
irons.
[0165] A representative peel ply based process is illustrated in
FIGS. 40-42. A portion of a peel ply fabric 602 is oriented so the
woven fibers in the fabric are along an x-axis 604 and a z-axis 606
based on an eventual striking plate orientation in a finished club.
In other examples, different orientations can be used. Peel ply
fabric weave is not generally or necessarily the same along the
warp and the weft directions, and in some examples, the warp and
weft are aligned preferentially along selected directions. As shown
in FIG. 41, a resulting striking plate 610 includes a face plate
612 and a cover layer 614 that has a textured striking surface 616.
A portion of the textured striking surface 616 is shown in FIG. 42
to illustrate the surface texture based on surface peaks 618 that
are separated by about 0.27 mm and having a height H of about 0.03
mm. In the example of FIGS. 40-42, the cover layer 610 is about 0.5
mm thick.
[0166] Representative surface profiles of peel ply based striking
surfaces are shown in FIGS. 43-44. FIG. 43 is portion of a
toe-to-heel surface profile scan performed with a stylus-based
surface profilometer as described further detail above. Relatively
rough profile portions 702 are separated by profile portions 704
that correspond to more gradual surface curvatures. A plurality of
peaks 706 in the rough profile portions 702 appear to correspond to
a stylus crossing over features defined by individual peel ply
fabric fibers. The smoother portions 704 appear to correspond to
stylus scanning along a feature that is defined along a fiber
direction. Surface peaks have a periodic separation of about 0.5 mm
and a height of about 20-30 .mu.m. FIG. 44 is a portion of a
similar scan to that of FIG. 43 but along a top-to-bottom
direction. Relatively smooth and rough areas alternate, and peak
spacing is about 0.6 mm, slightly larger than that in the
toe-to-heel direction, likely due to differing fiber spacings in
peel ply fabric warp and weft. FIG. 45 is a photograph of a portion
of a striking surface formed with a peel ply fabric.
[0167] An example striking plate 810 based on a machined or other
mold is shown in FIGS. 46-48. In this example, a surface texture
811 provided to a striking surface 816 is aligned with respect to a
club and a club head substantially along an x-axis as shown in FIG.
46. FIGS. 47-48 illustrate the texture 811 of the striking surface
816 that is formed as a surface of a cover layer 814 that is
situated on a face plate 812. As shown in FIG. 48, the cover layer
814 is about 0.5 mm thick, and the texture includes a plurality of
valleys 818 separated by about 0.34 mm and about 40 .mu.m deep.
FIG. 49 includes a portion of a stylus-based top-to-bottom surface
scan of a representative polymer surface showing bumps having a
center to center spacing of about 0.34 mm.
[0168] The following table summarize surface roughness parameters
associated with the scans of FIGS. 43-44 and 49. In typical
examples, measured surface roughness is greater than about 0.1
.mu.m, 1 .mu.m, 2 .mu.m, or 2.5 .mu.m and less than about 20 .mu.m,
10 .mu.m, 5 .mu.m, 4.5 .mu.m, or 4 .mu.m.
TABLE-US-00003 Toe-to-Heel Scan Toe-to-Heel Scan Top-to-Bottom Scan
Parameter (Tooled Mold) (Peel Ply Shaped) (Peel Ply Shaped) R.sub.a
6.90 .mu.m 8.31 .mu.m 7.07 .mu.m R.sub.z 29.4 .mu.m 49.0 .mu.m 48.7
.mu.m R.sub.p 9.9 .mu.m 26.9 .mu.m 27.4 .mu.m RPc 29.7/cm 44.4/cm
37.6/cm K.sub.u 2.41
[0169] A striking surface of a cover layer can be provided with a
variety of other roughness patterns some examples of which are
illustrated in FIGS. 36-39. Typically these patterns extend over
substantially the entire striking surface, but in some illustrated
examples only a portion of the striking surface is shown for
convenient illustration. Referring to FIGS. 36-37, a striking plate
402 includes a composite face plate 403 and a cover layer 404. A
striking surface 409 of the cover layer includes a patterned area
410 that includes a plurality of pattern features 412 that are
arranged in a two dimensional array. As shown in FIGS. 36-37, the
pattern features 412 are rectangular or square depressions formed
in the cover layer 404 and that extend along a +y-direction (i.e.,
inwardly towards an external surface 414 of the face plate 403). A
horizontal spacing (along an x-axis 420) of the pattern features is
dx and a vertical spacing (along a z-axis 422) is dz. These
spacings can be the same or different, and the features 412 can be
inwardly or outwardly directed and can be columns or depressions
having square, circular, elliptical, polygonal, oval, or other
cross-sections in an xz-plane. In addition, for cross-sectional
shapes that are asymmetric, the pattern features can be arbitrarily
aligned with respect to the x-axis 420 and the z-axis 422. The
pattern features 412 can be located in a regular array, but the
orientation of each of the pattern features can be arbitrary, or
the pattern features can be periodically arranged along the x-axis
420, the z-axis 422, or another axis in the xz-plane. As shown in
FIG. 36, a plurality of scorelines 430 are provided and are
typically colored so as to provide a high contrast. A maximum depth
dy of the pattern features 512 along the y-axis is between about 10
.mu.m and 100 .mu.m, between about 5 .mu.m and 50 .mu.m, or about 2
.mu.m and 25 .mu.m. The horizontal and vertical spacings are
typically between about 0.025 mm and 0.500 mm
[0170] While the pattern features 412 may have substantially
constant cross-sectional dimensions in one or more planes
perpendicular the xz-plane (i.e., vertical cross-sections), these
vertical cross-sections can vary along a y-axis 424 or as a
function of an angle of a cross-sectional plane with respect to the
x-axis, the y-axis, or the z-axis. For example, columnar
protrusions can have bases that taper outwardly, inwardly, or a
combination thereof along the y-axis 424, and can be tilted with
respect to the y-axis 424.
[0171] In an example shown in FIGS. 38-39, a cover layer 504
includes a plurality of pattern features 512 that are periodically
situated along an axis 514 that is tilted with respect to an x-axis
520 and a z-axis 522. The pattern features 512 are periodic in one
dimension, but in other examples, pattern features periodic along
one more axes that are tilted (or aligned with) x- and z-axes can
be provided. A plurality of scorelines 530 are provided (generally
in a face plate) and are colored so as to provide a high contrast.
As shown in FIG. 39, the cover layer 504 is secured to a face plate
503 and the pattern features 512 have a depth dy.
[0172] In other examples, pattern features can be periodic,
aperiodic, or partially periodic, or randomly situated. Spatial
frequencies associated with pattern features can vary, and pattern
feature size and orientation can vary as well. In some examples, a
roughened surface is defined as series of features that are
randomly situated and sized.
[0173] Similar striking plates can be provided for iron-type golf
clubs. While striking plates for wood-type golf clubs generally
have top-to-bottom and toe-to-heel curvatures (commonly referred to
as bulge and roll), striking plates for irons are typically flat.
Composite-based striking plates for iron-type clubs typically
include a polymer cover layer selected to protect the underlying
composite face plate. In some examples, similar striking surface
textures to those described above can be provided. In addition, one
or more conventional grooves are generally provided on the striking
surface. Such striking plates can be secured to iron-type golf club
bodies with various adhesives or otherwise secured.
Representative Polymer Materials
[0174] Representative polymer materials suitable for face plate
covers or caps are described herein.
DEFINITIONS
[0175] The term "bimodal polymer" as used herein refers to a
polymer comprising two main fractions and more specifically to the
form of the polymer's molecular weight distribution curve, i.e.,
the appearance of the graph of the polymer weight fraction as a
function of its molecular weight. When the molecular weight
distribution curves from these fractions are superimposed onto the
molecular weight distribution curve for the total resulting polymer
product, that curve will show two maxima or at least be distinctly
broadened in comparison with the curves for the individual
fractions. Such a polymer product is called bimodal. The chemical
compositions of the two fractions may be different.
[0176] The term "chain extender" as used herein is a compound added
to either a polyurethane or polyurea prepolymer, (or the prepolymer
starting materials), which undergoes additional reaction but at a
level sufficiently low to maintain the thermoplastic properties of
the final composition
[0177] The term "conjugated" as used herein refers to an organic
compound containing two or more sites of unsaturation (e.g.,
carbon-carbon double bonds, carbon-carbon triple bonds, and sites
of unsaturation comprising atoms other than carbon, such as
nitrogen) separated by a single bond.
[0178] The term "curing agent" or "curing system" as used
interchangeably herein is a compound added to either polyurethane
or polyurea prepolymer, (or the prepolymer starting materials),
which imparts additional crosslinking to the final composition to
render it a thermoset.
[0179] The term "(meth)acrylate" is intended to mean an ester of
methacrylic acid and/or acrylic acid.
[0180] The term "(meth)acrylic acid copolymers" is intended to mean
copolymers of methacrylic acid and/or acrylic acid.
[0181] The term "polyurea" as used herein refers to materials
prepared by reaction of a diisocyanate with a polyamine.
[0182] The term "polyurethane" as used herein refers to materials
prepared by reaction of a diisocyanate with a polyol.
[0183] The term "prepolymer" as used herein refers to any material
that can be further processed to form a final polymer material of a
manufactured golf ball, such as, by way of example and not
limitation, a polymerized or partially polymerized material that
can undergo additional processing, such as crosslinking.
[0184] The term "thermoplastic" as used herein is defined as a
material that is capable of softening or melting when heated and of
hardening again when cooled. Thermoplastic polymer chains often are
not cross-linked or are lightly crosslinked using a chain extender,
but the term "thermoplastic" as used herein may refer to materials
that initially act as thermoplastics, such as during an initial
extrusion process or injection molding process, but which also may
be crosslinked, such as during a compression molding step to form a
final structure.
[0185] The term "thermoplastic polyurea" as used herein refers to a
material prepared by reaction of a prepared by reaction of a
diisocyanate with a polyamine, with optionally addition of a chain
extender.
[0186] The "thermoplastic polyurethane" as used herein refers to a
material prepared by reaction of a diisocyanate with a polyol, with
optionally addition of a chain extender.
[0187] The term "thermoset" as used herein is defined as a material
that crosslinks or cures via interaction with as crosslinking or
curing agent. The crosslinking may be brought about by energy in
the form of heat (generally above 200 degrees Celsius), through a
chemical reaction (by reaction with a curing agent), or by
irradiation. The resulting composition remains rigid when set, and
does not soften with heating. Thermosets have this property because
the long-chain polymer molecules cross-link with each other to give
a rigid structure. A thermoset material cannot be melted and
re-molded after it is cured thus thermosets do not lend themselves
to recycling unlike thermoplastics, which can be melted and
re-molded.
[0188] The term "thermoset polyurethane" as used herein refers to a
material prepared by reaction of a diisocyanate with a polyol, and
a curing agent.
[0189] The term "thermoset polyurea" as used herein refers to a
material prepared by reaction of a diisocyanate with a polyamine,
and a curing agent.
[0190] The term "urethane prepolymer" as used herein is the
reaction product of diisocyante and a polyol.
[0191] The term "urea prepolymer" as used herein is the reaction
product of a diisocyanate and a polyamine.
[0192] The term "unimodal polymer" refers to a polymer comprising
one main fraction and more specifically to the form of the
polymer's molecular weight distribution curve, i.e., the molecular
weight distribution curve for the total polymer product shows only
a single maximum.
Materials
[0193] Polymeric materials generally considered useful for making
the golf club face cap according to the present invention include
both synthetic or natural polymers or blend thereof including
without limitation, synthetic and natural rubbers, thermoset
polymers such as other thermoset polyurethanes or thermoset
polyureas, as well as thermoplastic polymers including
thermoplastic elastomers such as metallocene catalyzed polymer,
unimodal ethylene/carboxylic acid copolymers, unimodal
ethylene/carboxylic acid/carboxylate terpolymers, bimodal
ethylene/carboxylic acid copolymers, bimodal ethylene/carboxylic
acid/carboxylate terpolymers, unimodal ionomers, bimodal ionomers,
modified unimodal ionomers, modified bimodal ionomers,
thermoplastic polyurethanes, thermoplastic polyureas, polyamides,
copolyamides, polyesters, copolyesters, polycarbonates,
polyolefins, halogenated (e.g. chlorinated) polyolefins,
halogenated polyalkylene compounds, such as halogenated
polyethylene [e.g. chlorinated polyethylene (CPE)], polyalkenamer,
polyphenylene oxides, polyphenylene sulfides, diallyl phthalate
polymers, polyimides, polyvinyl chlorides, polyamide-ionomers,
polyurethane-ionomers, polyvinyl alcohols, polyarylates,
polyacrylates, polyphenylene ethers, impact-modified polyphenylene
ethers, polystyrenes, high impact polystyrenes,
acrylonitrile-butadiene-styrene copolymers, styrene-acrylonitriles
(SAN), acrylonitrile-styrene-acrylonitriles, styrene-maleic
anhydride (S/MA) polymers, styrenic copolymers, functionalized
styrenic copolymers, functionalized styrenic terpolymers, styrenic
terpolymers, cellulosic polymers, liquid crystal polymers (LCP),
ethylene-propylene-diene terpolymers (EPDM), ethylene-vinyl acetate
copolymers (EVA), ethylene-propylene copolymers, ethylene vinyl
acetates, polyureas, and polysiloxanes and any and all combinations
thereof.
[0194] One preferred family of polymers for making the golf club
face cap of the present invention are the thermoplastic or
thermoset polyurethanes and polyureas made by combination of a
polyisiocyanate and a polyol or polyamine respectively. Any
isocyanate available to one of ordinary skill in the art is
suitable for use in the present invention including, but not
limited to, aliphatic, cycloaliphatic, aromatic aliphatic,
aromatic, any derivatives thereof, and combinations of these
compounds having two or more isocyanate (NCO) groups per
molecule.
[0195] Any polyol available to one of ordinary skill in the
polyurethane art is suitable for use according to the invention.
Polyols suitable for use include, but are not limited to, polyester
polyols, polyether polyols, polycarbonate polyols and polydiene
polyols such as polybutadiene polyols.
[0196] Any polyamine available to one of ordinary skill in the
polyurea art is suitable for use according to the invention.
Polyamines suitable for use include, but are not limited to,
amine-terminated hydrocarbons, amine-terminated polyethers,
amine-terminated polyesters, amine-terminated polycaprolactones,
amine-terminated polycarbonates, amine-terminated polyamides, and
mixtures thereof.
[0197] The previously described diisocyante and polyol or polyamine
components may be previously combined to form a prepolymer prior to
reaction with the chain extender or curing agent. Any such
prepolymer combination is suitable for use in the present
invention. Commercially available prepolymers include LFH580,
LFH120, LFH710, LFH1570, LF930A, LF950A, LF601D, LF751D, LFG963A,
LFG640D.
[0198] One preferred prepolymer is a toluene diisocyanate
prepolymer with polypropylene glycol. Such polypropylene glycol
terminated toluene diisocyanate prepolymers are available from
Uniroyal Chemical Company of Middlebury, Conn., under the trade
name ADIPRENE.RTM. LFG963A and LFG640D. Most preferred prepolymers
are the polytetramethylene ether glycol terminated toluene
diisocyanate prepolymers including those available from Uniroyal
Chemical Company of Middlebury, Conn., under the trade name
ADIPRENE.RTM. LF930A, LF950A, LF601D, and LF751D.
[0199] Polyol chain extenders or curing agents may be primary,
secondary, or tertiary polyols. Diamines and other suitable
polyamines may be added to the compositions of the present
invention to function as chain extenders or curing agents. These
include primary, secondary and tertiary amines having two or more
amines as functional groups.
[0200] Depending on their chemical structure, curing agents may be
slow- or fast-reacting polyamines or polyols. As described in U.S.
Pat. Nos. 6,793,864, 6,719,646 and copending U.S. Patent
Publication No. 2004/0201133 A1, (the contents of all of which are
hereby incorporated herein by reference).
[0201] Suitable curatives for use in the present invention are
selected from the slow-reacting polyamine group include, but are
not limited to, 3,5-dimethylthio-2,4-toluenediamine;
3,5-dimethylthio-2,6-toluenediamine; N,N'-dialkyldiamino diphenyl
methane; trimethylene-glycol-di-p-aminobenzoate;
polytetramethyleneoxide-di-p-aminobenzoate, and mixtures thereof.
Of these, 3,5-dimethylthio-2,4-toluenediamine and
3,5-dimethylthio-2,6-toluenediamine are isomers and are sold under
the trade name ETHACURE.RTM. 300 by Ethyl Corporation. Trimethylene
glycol-di-p-aminobenzoate is sold under the trade name POLACURE
740M and polytetramethyleneoxide-di-p-aminobenzoates are sold under
the trade name POLAMINES by Polaroid Corporation.
N,N'-dialkyldiamino diphenyl methane is sold under the trade name
UNILINK.RTM. by UOP. Suitable fast-reacting curing agent can be
used include diethyl-2,4-toluenediamine,
4,4''-methylenebis-(3-chloro,2,6-diethyl)-aniline (available from
Air Products and Chemicals Inc., of Allentown, Pa., under the trade
name LONZACURE.RTM.), 3,3'-dichlorobenzidene;
3,3'-dichloro-4,4'-diaminodiphenyl methane (MOCA);
N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine and Curalon L, a
trade name for a mixture of aromatic diamines sold by Uniroyal,
Inc. or any and all combinations thereof. A preferred fast-reacting
curing agent is diethyl-2,4-toluene diamine, which has two
commercial grades names, Ethacure.RTM. 100 and Ethacure.RTM.100LC
commercial grade has lower color and less by-product. Blends of
fast and slow curing agents are especially preferred.
[0202] In another preferred embodiment the polyurethane or polyurea
is prepared by combining a diisocyanate with either a polyamine or
polyol or a mixture thereof and one or more dicyandiamides. In a
preferred embodiment the dicyandiamide is combined with a urethane
or urea prepolymer to form a reduced-yellowing polymer composition
as described in U.S. Patent Application No. 60/852,582 filed on
Oct. 17, 2006, the entire contents of which are herein incorporated
by reference in their entirety. Another preferred family of
polymers for making the golf club face cap of the present invention
are thermoplastic ionomer resins. One family of such resins was
developed in the mid-1960's, by E.I. DuPont de Nemours and Co., and
sold under the trademark SURLYN.RTM.. Preparation of such ionomers
is well known, for example see U.S. Pat. No. 3,264,272. Generally
speaking, most commercial ionomers are unimodal and consist of a
polymer of a mono-olefin, e.g., an alkene, with an unsaturated
mono- or dicarboxylic acids having 3 to 12 carbon atoms. An
additional monomer in the form of a mono- or dicarboxylic acid
ester may also be incorporated in the formulation as a so-called
"softening comonomer". The incorporated carboxylic acid groups are
then neutralized by a basic metal ion salt, to form the ionomer.
The metal cations of the basic metal ion salt used for
neutralization include Li.sup.+, Na.sup.+, K.sup.+, Zn.sup.2+,
Ca.sup.2+, Co.sup.2+, Ni.sup.2+, Cu.sup.2+, Pb.sup.2+, and
Mg.sup.2+, with the Li.sup.+, Na.sup.+, Ca.sup.2+, Zn.sup.2+, and
Mg.sup.2+ being preferred. The basic metal ion salts include those
derived by neutralization of for example formic acid, acetic acid,
nitric acid, and carbonic acid. The salts may also include hydrogen
carbonate salts, metal oxides, metal hydroxides, and metal
alkoxides.
[0203] Today, there are a wide variety of commercially available
ionomer resins based both on copolymers of ethylene and
(meth)acrylic acid or terpolymers of ethylene and (meth)acrylic
acid and (meth)acrylate, all of which many of which are be used as
a golf club component such as a cover layer that provides a
striking surface. The properties of these ionomer resins can vary
widely due to variations in acid content, softening comonomer
content, the degree of neutralization, and the type of metal ion
used in the neutralization. The full range commercially available
typically includes ionomers of polymers of general formula, E/X/Y
polymer, wherein E is ethylene, X is a C.sub.3 to C.sub.8
.alpha.,.beta. ethylenically unsaturated carboxylic acid, such as
acrylic or methacrylic acid, and is present in an amount from about
2 to about 30 weight % of the E/X/Y copolymer, and Y is a softening
comonomer selected from the group consisting of alkyl acrylate and
alkyl methacrylate, such as methyl acrylate or methyl methacrylate,
and wherein the alkyl groups have from 1-8 carbon atoms, Y is in
the range of 0 to about 50 weight % of the E/X/Y copolymer, and
wherein the acid groups present in said ionomeric polymer are
partially neutralized with a metal selected from the group
consisting of lithium, sodium, potassium, magnesium, calcium,
barium, lead, tin, zinc or aluminum, and combinations thereof.
[0204] The ionomer may also be a so-called bimodal ionomer as
described in U.S. Pat. No. 6,562,906 (the entire contents of which
are herein incorporated by reference). These ionomers are bimodal
as they are prepared from blends comprising polymers of different
molecular weights In addition to the unimodal and bimodal ionomers,
also included are the so-called "modified ionomers" examples of
which are described in U.S. Pat. Nos. 6,100,321, 6,329,458 and
6,616,552 and U.S. Patent Publication U.S. 2003/0158312 A1, the
entire contents of all of which are herein incorporated by
reference. An example of such a modified ionomer polymer is
DuPont.RTM. HPF-1000 available from E. I. DuPont de Nemours and Co.
Inc.
[0205] Also useful for making the golf club face cap of the present
invention is a blend of an ionomer and a block copolymer. A
preferred block copolymer is SEPTON HG-252. Such blends are
described in more detail in commonly-assigned U.S. Pat. No.
6,861,474 and U.S. Patent Publication No. 2003/0224871 both of
which are incorporated herein by reference in their entireties.
[0206] In a further embodiment, the golf club face cap of the
present invention can comprise a composition prepared by blending
together at least three materials, identified as Components A, B,
and C, and melt-processing these components to form in-situ, a
polymer blend composition incorporating a pseudo-crosslinked
polymer network. Such blends are described in more detail in
commonly-assigned U.S. Pat. No. 6,930,150, to Kim et al., the
content of which is incorporated by reference herein in its
entirety.
[0207] Component A is a monomer, oligomer, prepolymer or polymer
that incorporates at least five percent by weight of at least one
type of an acidic functional group. Examples of such polymers
suitable for use as include, but are not limited to,
ethylene/(meth)acrylic acid copolymers and ethylene/(meth)acrylic
acid/alkyl (meth)acrylate terpolymers, or ethylene and/or propylene
maleic anhydride copolymers and terpolymers.
[0208] As discussed above, Component B can be any monomer,
oligomer, or polymer, preferably having a lower weight percentage
of anionic functional groups than that present in Component A in
the weight ranges discussed above, and most preferably free of such
functional groups. Preferred materials for use as Component B
include polyester elastomers marketed under the name PEBAX and
LOTADER marketed by ATOFINA Chemicals of Philadelphia, Pa.; HYTREL,
FUSABOND, and NUCREL marketed by E.I. DuPont de Nemours & Co.
of Wilmington, Del.; SKYPEL and SKYTHANE by S.K. Chemicals of
Seoul, South Korea; SEPTON and HYBRAR marketed by Kuraray Company
of Kurashiki, Japan; ESTHANE by Noveon; and KRATON marketed by
Kraton Polymers. A most preferred material for use as Component B
is SEPTON HG-252. Component C is a base capable of neutralizing the
acidic functional group of Component A and is a base having a metal
cation. These metals are from groups IA, IB, IIA, IIB, IIIA, IIIB,
IVA, IVB, VA, VB, VIIA, VIIB, VIIB and VIIIB of the periodic table.
Examples of these metals include lithium, sodium, magnesium,
aluminum, potassium, calcium, manganese, tungsten, titanium, iron,
cobalt, nickel, hafnium, copper, zinc, barium, zirconium, and tin.
Suitable metal compounds for use as a source of Component C are,
for example, metal salts, preferably metal hydroxides, metal
oxides, metal carbonates, or metal acetates. The composition
preferably is prepared by mixing the above materials into each
other thoroughly, either by using a dispersive mixing mechanism, a
distributive mixing mechanism, or a combination of these.
[0209] In a further embodiment, the golf club face cap of the
present invention can comprise a polyamide. Specific examples of
suitable polyamides include polyamide 6; polyamide 11; polyamide
12; polyamide 4,6; polyamide 6,6; polyamide 6,9; polyamide 6,10;
polyamide 6,12; polyamide MXD6; PAl2, CX; PA12, IT; PPA; PA6, IT;
and PA6/PPE.
[0210] The polyamide may be any homopolyamide or copolyamide. One
example of a group of suitable polyamides is thermoplastic
polyamide elastomers. Thermoplastic polyamide elastomers typically
are copolymers of a polyamide and polyester or polyether. For
example, the thermoplastic polyamide elastomer can contain a
polyamide (Nylon 6, Nylon 66, Nylon 11, Nylon 12 and the like) as a
hard segment and a polyether or polyester as a soft segment. In one
specific example, the thermoplastic polyamides are amorphous
copolyamides based on polyamide (PA 12). Suitable amide block
polyethers include those as disclosed in U.S. Pat. Nos. 4,331,786;
4,115,475; 4,195,015; 4,839,441; 4,864,014; 4,230,848 and
4,332,920.
[0211] One type of polyetherester elastomer is the family of Pebax,
which are available from Elf-Atochem Company. Preferably, the
choice can be made from among Pebax 2533, 3533, 4033, 1205, 7033
and 7233. Blends or combinations of Pebax 2533, 3533, 4033, 1205,
7033 and 7233 can also be prepared, as well. Some examples of
suitable polyamides for use include those commercially available
under the trade names PEBAX, CRISTAMID and RILSAN marketed by
Atofina Chemicals of Philadelphia, Pa., GRIVORY and GRILAMID
marketed by EMS Chemie of Sumter, S.C., TROGAMID and VESTAMID
available from Degussa, and ZYTEL marketed by E.I. DuPont de
Nemours & Co., of Wilmington, Del.
[0212] The polymeric compositions used to prepare the golf club
face cap of the present invention also can incorporate one or more
fillers. Such fillers are typically in a finely divided form, for
example, in a size generally less than about 20 mesh, preferably
less than about 100 mesh U.S. standard size, except for fibers and
flock, which are generally elongated. Filler particle size will
depend upon desired effect, cost, ease of addition, and dusting
considerations. The appropriate amounts of filler required will
vary depending on the application but typically can be readily
determined without undue experimentation.
[0213] The filler preferably is selected from the group consisting
of precipitated hydrated silica, limestone, clay, talc, asbestos,
barytes, glass fibers, aramid fibers, mica, calcium metasilicate,
barium sulfate, zinc sulfide, lithopone, silicates, silicon
carbide, diatomaceous earth, carbonates such as calcium or
magnesium or barium carbonate, sulfates such as calcium or
magnesium or barium sulfate, metals, including tungsten, steel,
copper, cobalt or iron, metal alloys, tungsten carbide, metal
oxides, metal stearates, and other particulate carbonaceous
materials, and any and all combinations thereof. Preferred examples
of fillers include metal oxides, such as zinc oxide and magnesium
oxide. In another preferred embodiment the filler comprises a
continuous or non-continuous fiber. In another preferred embodiment
the filler comprises one or more so called nanofillers, as
described in U.S. Pat. No. 6,794,447 and copending U.S. patent
application Ser. No. 10/670,090 filed on Sep. 24, 2003 and
copending U.S. patent application Ser. No. 10/926,509 filed on Aug.
25, 2004, the entire contents of each of which are incorporated
herein by reference.
[0214] Another particularly well-suited additive for use in the
compositions of the present invention includes compounds having the
general formula:
(R.sub.2N).sub.m--R'--(X(O).sub.nOR.sub.y).sub.m,
wherein R is hydrogen, or a C.sub.1-C.sub.20 aliphatic,
cycloaliphatic or aromatic systems; R' is a bridging group
comprising one or more C.sub.1-C.sub.20 straight chain or branched
aliphatic or alicyclic groups, or substituted straight chain or
branched aliphatic or alicyclic groups, or aromatic group, or an
oligomer of up to 12 repeating units including, but not limited to,
polypeptides derived from an amino acid sequence of up to 12 amino
acids; and X is C or S or P with the proviso that when X=C, n=1 and
y=1 and when X=S, n=2 and y=1, and when X=P, n=2 and y=2. Also,
m=1-3. These materials are more fully described in copending U.S.
patent application Ser. No. 11/182,170, filed on Jul. 14, 2005, the
entire contents of which are incorporated herein by reference. Most
preferably the material is selected from the group consisting of
4,4'-methylene-bis-(cyclohexylamine)-carbamate (commercially
available from R.T. Vanderbilt Co., Norwalk Conn. under the
tradename Diak.RTM. 4), 11-aminoundecanoicacid, 12-aminododecanoic
acid, epsilon-caprolactam; omega-caprolactam, and any and all
combinations thereof.
[0215] If desired, the various polymer compositions used to prepare
the golf club face cap of the present invention can additionally
contain other conventional additives such as, antioxidants, or any
other additives generally employed in plastics formulation. Agents
provided to achieve specific functions, such as additives and
stabilizers, can be present. Exemplary suitable ingredients include
plasticizers, pigments colorants, antioxidants, colorants,
dispersants, U.V. absorbers, optical brighteners, mold releasing
agents, processing aids, fillers, and any and all combinations
thereof. UV stabilizers, or photo stabilizers such as substituted
hydroxphenyl benzotriazoles may be utilized in the present
invention to enhance the UV stability of the final compositions. An
example of a commercially available UV stabilizer is the stabilizer
sold by Ciba Geigy Corporation under the tradename TINUVIN
[0216] Whereas the invention has been described in connection with
representative embodiments, it will be understood that the
invention is not limited to those embodiments. On the contrary, the
invention is intended to encompass all modifications, alternatives,
and equivalents as may fall within the spirit and scope of the
invention, as defined by the appended claims.
* * * * *