Note: Descriptions are shown in the official language in which they were submitted.
CA 02861583 2014-09-03
ARTICLE WITH PROTECTIVE SHEATH
[0001] The present application claims priority to U.S. Prov. Patent App. Ser.
No.
61/875,144, filed on September 9, 2013, which is incorporated herein in its
entirety.
FIELD OF THE INVENTION
[0002] The invention relates to the addition of a protective sheath for
providing enhanced
performance and durability to at least part of an article specifically to
sports equipment such
as ice hockey sticks, field hockey sticks, lacrosse sticks, baseball/softball
bats, and other
articles comprising an elongated member/shaft and optionally a head portion
such as a blade
or webbing in a frame.
BACKGROUND OF THE INVENTION
[0003] Due to the competitive nature of many sports, players frequently seek
ways to
improve athletic equipment in order to gain a competitive advantage. Equipment
manufacturers therefore investigate various materials and designs to enhance
sports
equipment performance. As can be appreciated, finding a suitable combination
of materials
and designs to meet a set of performance criteria such as being durable while
remaining
lightweight remains challenging and frequently different solutions are
required for different
sports articles.
[0004] For example, hockey sticks were initially made of wood. Over the years,
composite
hockey sticks have gained popularity notwithstanding having durability issues.
Metal-
containing hockey sticks based on aluminum have been proposed as well but they
can suffer
from a number of deficiencies including undesirable vibrations into the hands
and arms of a
player. A metal-containing hockey stick can also emit an undesirable high-
pitch metallic
sound upon impact with the puck.
[0005] Attempts have been made to address these deficiencies and multi-layered
or multi-
walled designs using different materials, such as metals, polymers, and
composites have been
proposed. While providing some benefits, these attempts can still be lacking
in certain areas
of performance, e.g., in terms of durability, feel and sound upon impact with
a ball or puck.
Moreover, some of these attempts can involve manufacturing techniques that are
cumbersome and expensive.
100061 Conventional hockey sticks comprise a shaft and an adjoining blade. The
blade has a
body and a neck that connects the body to the shaft. The blade has a heel at
the end of the
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body below the neck and a toe disposed at end of the body opposite the heel.
The body has
two main faces, a front face and a rear face, that each extend from the heel
to the toe. The
front face comprises the primary puck striking surface of the blade. When
viewed from above
hockey stick blades are curved to form a forward facing "pocket". The
curvature of the blade
plays a significant role in a player's ability both to control the puck and
for accuracy when the
player is shooting. As each player has his own preference with regard to the
curvature of the
blade manufacturers typically provide hockey sticks with many different shaped
blades.
Hockey stick blades with smooth faces can make handling of the puck at times
challenging,
i.e., it may be difficult to control the relative position of the puck and the
blade, as well as to
accurately move the puck along the surface of the blade when the two are in
contact. Hockey
players therefore often wrap a polymeric tape around their blades.
[0007] It is against this background that a need arose to develop the articles
described
herein.
SUMMARY OF THE INVENTION
[0008] In one aspect, the invention relates to a protective sheath for an
article such as a
sports article. The sports article can be any of a variety of sports equipment
and associated
components, e.g., a hockey stick and a lacrosse stick, various racquets and
bats, and other
such shafts comprising an elongated member/shafts/sticks and a head portion
such as a blade,
webbing in a frame, or tubular member/barrel designed to strike a ball or
puck.
100091 In one embodiment, the sports article is used in contact sports where,
in addition to
the contact between the sports article and the ball/puck or the ground,
frequent contact
between the sports article and the opposing player's sport article occurs such
as in ice-, field-,
ball- and street-hockey or lacrosse. The sport article must ideally be both
lightweight and
strong, however, these requirements are often incompatible and a reduction in
weight often
results in a loss of strength and/or durability. The sports article used in
these games must be
able to withstand a large number of impacts which often are concentrated at
the edges and,
over time, can result in increased damage to the structure and ultimately,
premature failure. In
addition, abrasion of selected surfaces such as the edges contacting the
playing surface needs
to be minimized. To improve the performance and durability a novel multi-
layered protective
sheath is applied to part.or substantially the entire outer surface of the
sports article.
[0010] The basic article typically includes a substrate made of reinforced
composites such as
carbon fiber, aramid fiber and glass fiber reinforced polymers and the
inventive protective
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multi-layer sheath, comprising alternating layers of highly ductile and less
ductile coatings, is
applied to at least part of the outer surface thereof.
100111 In one embodiment, the inventive protective sheath is composed of
alternating layers
of ductile/malleable materials and relatively rigid materials, i.e.,
alternating layers of
materials of high and low ductility, i.e., defined herein as having an
elongation to failure of
>10% or <10% as per ASTM E8, respectively. Each layer can be composed of
sublayers, and
the total layer thickness of each layer of high or low ductility is in the
range of between 0.25
and 150[Im.
100121 In one embodiment,, the inventive protective sheath is composed of
multiple layers
comprising at least one polymeric material layer, representing the ductile
layer, and at least
one metallic material layer, representing the less ductile layer.
[0013] In one embodiment, the inventive protective sheath comprises at least
one highly
ductile polymer coating having a thickness between 25 and 150m, preferably
between 50
and 100um, which is directly applied onto and intimately bonded with the
reinforced
composite sports article substrate.
[0014] In one embodiment, the inventive protective sheath polymer coating
comprises at
least one elastomer layer having a ductility greater than 10% elongation to
failure, preferably
equal to or greater than 15% and more preferably equal to or greater than 25%
elongation to
failure.
[0015] In one embodiment, the inventive protective sheath comprises an
elastomer layer
with an amorphous microstructure.
[0016] In one embodiment, the inventive protective sheath includes
electrodeposited or
electroformed metallic material layers of high ductility.
100171 In one embodiment, the inventive protective sheath includes
electrodeposited or
electroformed metallic material layers of low ductility.
[0018] In one embodiment, the inventive protective sheath includes metallic
material
nanolaminates having sublayers having a thickness between 2 and 250nm,
preferably
between 2 and 100nm of high, low or alternating high and low ductility. In
this case the
"nanolaminate" is considered to represent one single "layer" and, depending on
the ductility
of the entire nanolaminate, the "layer" is considered to represent a layer of
high or low
ductility.
[0019] In one embodiment, the inventive protective sheath includes metallic
material layers
applied by electroless deposition.
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100201 In one embodiment, the inventive protective sheath comprises at least
one fine-
grained metal or metal alloy coating layer having a thickness between 20 and I
00[im applied,
e.g., by electrodeposition.
10021] In another embodiment, the inventive protective sheath comprises at
least one grain-
refined metallic material layer having an average grain size that is in the
range of 2nm to
100nm, preferably an average grain-size between 15 and 75nm, a hardness that
is in the range
of 300 Vickers to 1,000 Vickers, preferably between 300 and 750 Vickers, and a
ductility that
is in the range of 1 to <10% elongation to failure, preferably between 2 and
7.5% elongation
to failure.
100221 In one embodiment, the inventive protective sheath comprises at least
one
amorphous metal or metal alloy coating layer having a thickness between 0.5
and 1(4tm and a
ductility that is in the range of 0 to 5% elongation to failure, preferably in
the range of 0.1 to
2.5%.
100231 In one embodiment, the inventive protective sheath provides for a
sports article that
has an increased ability to withstand impact along its edges and sharp
corners.
100241 In one embodiment, the inventive protective sheath provides for an
article such as a
sports article with enhanced protection at the edges and sharp corners thereof
100251 In one embodiment, the sports article includes a graphite/metal
composite shaft, tube
or the like, incorporating a protective sheath representing at least 3%, such
as at least 5% or
at least 10% or at least 20%, and up to 40%, 50% or 75%, of the total weight
of the article.
100261 In one embodiment, the sports article includes a composite shaft, tube
or the like,
incorporating a protective sheath representing at least 3%, such as between 5%
and 75%,
preferably between 10% and 60%, and more preferably between 20% and 50% of the
cross
sectional weight of the article.
100271 In one embodiment, the sports article includes a composite shaft, tube
or the like,
incorporating a protective sheath which covers between 10% and 100% of the
outer length of
the shaft, including up to 25% of the outer length of the shaft, up to 50% of
the outer length
of the shaft, up to 75% of the outer length of the shaft, and up to 100% of
the outer length of
the shaft. The protective sheath can be continuous or discontinuous, i.e.,
only the edges of the
shaft can be covered by the protective sheath or the protective sheath forms a
regular or
irregular pattern with up to 25% of the outer surface area of the shaft, or up
to 50% of the
outer surface area of the shaft or even up to 75% of the outer surface area of
the shaft being
covered by the protective sheath.
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100281 In one embodiment, the addition of the protective sheath decreases the
performance
loss as measured by either flexural load to fracture or fatigue life after
impact of the article by
>20%, preferably >50% when compared to the same article without the addition
of the
protective sheath.
100291 In one embodiment, the addition of the protective sheath to the sports
article provides
at least 10% increase in load failure, preferably at least 20% increase in
load failure, and
more preferably at least 30% increase in load failure. Further, the addition
of the protective
sheath to the sports article provides at least 5% increase in deflection to
failure, preferably at
least 10% increase in deflection to failure, and more preferably at least 15%
increase in
deflection to failure.
100301 In one embodiment, the protective sheath applied to at least part of
the outer surface
of the article includes at least a first layer and a second layer adjacent to
the first layer. At
least one of the layers includes a polymeric material of high ductility and at
least one of the
adjacent layers includes a metallic material, preferably a grain-refined
metallic material.
100311 The person skilled in the art knows that grain-refined metallic
materials can be
formed as high-strength coatings of pure metals and/or alloys of metals
selected from the
group of Ag, Au, Co, Cu, Fe, Ni, Sn, Fe, and Zn, optionally with alloying
elements selected
from the group of Mo, W, B, C, P, S, and Si, and optionally metal matrix
composites of pure
metals or alloys with particulate additives, such as powders, fibers,
nanotubes, flakes, metal
powders, metal alloy powders, and metal oxide powders of Al, Co, Cu, Mg, Ni,
Sc, Si, Sn, Ti,
V, and Zn; nitrides of Al, Sc and Ti, B and Si; C (e.g., graphite, diamond,
nanotubes);
carbides of B, Cr, Bi, Si, and W; and self-lubricating materials such as MoS2
or organic
materials such as PTFE. Depending on the composition, the average grain size
and the use of
particulate additions, the ductility of the grain-refined metallic materials
can extend from
highly brittle to highly ductile, with the elongation to failure ranging from
as low as much
less than (<1 1% to as high as much greater than (>>) 30%. Electroplating can
be employed
as the process for creating high strength coatings on metallic components or
on non-
conductive components that have been metallized to render them suitable for
plating. In an
alternative embodiment, the process can be used to electroform a stand-alone
metallic article
on a mandrel or other suitable temporary substrate and, after reaching a
desired plating
thickness, the free-standing electroformed article can be removed from the
temporary
substrate such as described, e.g. in PCT Publication No. WO 2004/001100, US
8,025,979 and
US 7,553,553, the disclosures of which are incorporated herein by reference in
their entirety.
CA 02861583 2014-09-03
[0032] In an embodiment of the invention, electrodeposited metallic
coatings/layers
optionally contain between 2.5% and 50% by volume particulate. The particulate
can be
selected from the group of metal powders, metal alloy powders, and metal oxide
powders of
Al, Co, Cu, In, Mg, Ni, Si, Sn, V, and Zn; nitrides of Al, B, Sc, Si and Ti; C
(e.g., graphite or
diamond); carbides of B, Cr, Si, and W; MoS7; and organic materials such as
PTFE and other
polymeric materials. The particulate average particle size is typically below
1011m, such as
below 51arn, below 1,000nm (or 11.im), or below 500nm.
[0033] In one embodiment of the invention, after forming, the protective
sheath is heat-
treated to achieve added strengthening and enhance bonding between layers or
alter the
mechanical material properties of one or more of its layers.
[0034] According to an embodiment of the invention, the protective sheath can
be formed
on selected areas of articles, such as on hockey blades and sticks, lacrosse
sticks, baseball
bats, golf club face plates or sections of golf club shafts, frames or other
parts for bicycles,
and the like, without the need to coat an entire article.
[0035] According to an embodiment of the invention, patches or sleeves of
grain-refined
materials, which need not be uniform in thickness or composition, can be
electrodeposited in
order to, e.g., form a thicker coating on selected sections or sections
particularly prone to
heavy use or abuse, such as the bottom edge or face of hockey stick blades
which are in
frequent contact with the playing surface or the edges of the stick prone to
being contacted by
another player's stick.
[0036] According to an embodiment of the invention, the protective sheath can
be graded or
layered in the deposit direction and/or along the length as described in US
2011/0256356, the
disclosure of which is incorporated herein by reference in its entirety.
[0037] Accordingly, the present invention in one embodiment is directed to a
hockey stick
comprising:
(i) a shaft portion comprising fiber reinforced composite materials and
including a
distal or grip end and a proximal end, and a blade portion connected to the
proximal end of
the shaft portion; and
(ii) a protective sheath covering at least an edge of the proximal end of the
shaft
portion up to 100% of an outer length of the shaft portion; said protective
sheath representing
<50% of the total overall weight of said hockey stick; said protective sheath
being composed
of a multi-layer structure comprising at least two layers each having a
thickness between 0.25
and 150um; said multi-layer structure comprising a polymer layer having a bulk
tensile
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elongation to failure of >10% in intimate contact with the fiber reinforced
composite material
of the shaft portion of the hockey stick followed by at least one metallic
layer having a bulk
tensile elongation to failure of <10%.
100381 Accordingly, the present invention in another embodiment is directed to
a hockey
stick comprising:
(i) a shaft portion including a distal or grip end and a proximal end, and a
blade
portion connected to the proximal end of the shaft portion, each of the shaft
portion and blade
portion comprising fiber reinforced composite materials; and
(ii) a protective sheath covering at least outer edges of the blade portion
and extending
beyond at least an edge of the proximal end of the shaft portion up to 50% of
an outer length
of the shaft portion; said protective sheath having a surface roughness Rõ in
the range of 2.5
to 151..tm and representing between 3 and 50% of the total overall weight of
said hockey stick;
said protective sheath being composed of a multi-layer structure containing at
least two
layers, preferably at least three or four layers, each layer having a
thickness between 0.25 and
150iim; preferably between 0.5 and 1001õtm, and a total overall thickness
between 50 and
250vim; preferably between 75 and 150 m, said multi-layer structure comprising
alternating
layers having an elongation to failure of <10% and layers having an elongation
to failure of
>10%; said multi-layer structure comprising a polymer layer having an
elongation to failure
of >10% in intimate contact with the fiber reinforced composite material of
the hockey stick
followed by one metallic layer having an elongation to failure of <10%;
followed by another
metallic layer having an elongation to failure of >10%; followed by another
metallic layer
having an elongation to failure of <10% and a minimum yield strength according
to ASTM
E8 of 600MPa.
100391 Accordingly, the present invention in another embodiment is directed to
a hockey
stick comprising:
(i) a shaft portion including a distal end and a proximal end, and a blade
portion
connected to the proximal end of the shaft portion, each of the shaft portion
and blade portion
comprising fiber reinforced composite materials; and
(ii) a protective sheath covering at least outer edges of the blade portion
and extending
beyond at least an edge of the proximal end of the shaft portion up to 50% of
an outer length
of the shaft portion; said protective sheath having a surface roughness Ra in
the range of 2.5
to 151Am and representing between 3 and 50% of the total overall weight of
said hockey stick;
said protective sheath being composed of a multi-layer structure containing at
least four
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layers each having a thickness between 0.25 and 1501,1m; said multi-layer
structure
comprising alternating layers having an elongation to failure of <10% and
layers having an
elongation to failure of >10%; said multi-layer structure comprising a polymer
layer having
an elongation to failure of >10% in intimate contact with the fiber reinforced
composite
material of the hockey stick and at least one metallic layer having an
elongation to failure of
<10% selected from the group of Co, Cu, Fe and Ni having an average grain size
that is in the
range of 2nm to 5,000nm, a yield strength in the range of 200MPa to 2,750MPa,
and a
hardness in the range of 300 Vickers to 1,000 Vickers.
100401 Accordingly, the present invention in another embodiment is directed to
a hockey
stick comprising:
(i) a shaft portion including a distal end and a proximal end, said shaft
portion
comprising a top face and a front face, said top face being narrower than said
front face and
oriented perpendicular to said front face, and a blade portion connected to
the proximal end
of the shaft portion; and
(ii) a protective sheath comprising at least one metallic layer covering at
least part of
an outer length of said shaft portion;
wherein said shaft portion having the protective sheath has a loss of peak
load
performance measured on the front face of less than 30% after being subjected
to an impact
force of 15J on the top face, i.e., perpendicular to the initial impact, said
peak load
performance being determined by securely mounting said shaft portion on two
locations
50cm apart and applying the load half way between the mounting locations using
a 1/2"
diameter load element.
100411 Accordingly, the present invention in another embodiment is directed to
an article
comprising a shaft portion comprising a fiber reinforced polymer:
(i) said shaft portion including a distal or grip end and a proximal end, said
shaft
portion comprising a top face and a front face, said top face being oriented
perpendicular to
said front face; and
(ii) a protective sheath comprising at least one metallic layer covering at
least part of
an outer length of said shaft portion;
wherein said shaft portion having said protective sheath after a 15J impact on
the top
face has an average peak load value on the front face exceeding the average
peak load value
on the shaft portion devoid of said protective sheath and not subjected to the
15J impact,
wherein said peak load value is determined by securely mounting said shaft
portion on two
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locations 50cm apart and applying the load or impact force half way between
the mounting
locations using a I/2- diameter load element.
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] For a better understanding of the nature and objects of some
embodiments of the
invention, reference should be made to the following detailed description
taken in
conjunction with the accompanying drawing.
100431 FIG. 1 illustrates a perspective view, taken from the front of an
article (e.g., a
hockey stick) according to one embodiment of the present invention.
DETAILED DESCRIPTION
[00441 Embodiments of the invention relate to one or more protective sheaths
to be applied
to lightweight articles, such as sports articles, e.g., hockey sticks,
lacrosse sticks, baseball or
softball bats, tennis, squash, racquetball and badminton racquets and the
like.
100451 The exemplary article of the present invention, by way of example only,
will be
described hereinafter in relation to ice hockey sticks, but it is understood
that the invention
herein described and claimed may be suitably adapted to other applications and
in particular
to other sports.
100461 Specifically to hockey sticks, some hockey shafts use a solid
construction while
others comprise a hollow core. Most blades are solid but they can contain foam
inserts such
as polyurethane foam. Shafts and some blades of a composite construction
comprise various
layers of materials sandwiched together. Wood-based hockey sticks are
inexpensive but
heavy while aluminum-based hockey sticks are prone to buckling failure.
Composite hockey
sticks with numerous plies of reinforcing fibers embedded in a polymer matrix
have rapidly
gained popularity. Composite hockey sticks are, however, particularly
vulnerable to failure
along their edges, i.e., where one side surface intersects with an adjacent
side surface, often at
an angle of close to 90 . Impacts are often concentrated at these edges and
hockey sticks that
are subject to repeated impact on their edges rapidly wear out, with paint and
decals wearing
off, and nicks and gouges forming therein, or they simply break and fail
catastrophically,
frequently at inopportune times during a game. In the case of hockey sticks,
the damaging
impacts typically occurs on a top face of the shaft by being impacted
repeatedly with other
sticks, while breakage usually occurs on a front face of the shaft when
shooting the puck,
when bending the hockey stick perpendicular to the top face typically exposed
to the
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damaging impacts. Similar situations occur with other shafts/stick used in
sports which have
similar or different cross sections, such as a lacrosse stick which typically
has eight different
faces.
[0047] Modern hockey sticks, for example, can comprise one or more reinforcing
fibers
such as carbon fiber, aramid fiber and glass fibers embedded in a polymer
matrix. It is known
that upon impact fiber cracking, delamination of the individual plies, and
fiber matrix
debonding can occur, significantly reducing the residual strength of the
composite structure,
even though no visible damage is observed and catastrophic failure, e.g.,
"unexpected"
breaking of the hockey stick, can ultimately result.
[0048] Therefore there is a need to improve the performance of reinforced
composite
material structures with respect to energy absorption, damage resistance,
performance and
durability. This enhancement is achieved by applying a protective sheath
according to the
present invention to at least part of an outer surface of the article, such as
sports articles prone
to similar failure modes (e.g., hockey sticks).
[0049] Articles in accordance with various embodiments of the invention can be
formed by
applying one or more protective sheaths having a number of desirable
performance
characteristics. Examples of sports articles include a variety of sports
equipment and
associated components, such as hockey sticks, hockey skate frames, lacrosse
sticks, golf club
heads, golf face plates, golf shafts, baseball bats, softball bats, tennis
rackets, squash rackets,
racquetball rackets, bicycle frames, bicycle seat posts, bicycle linkage
systems, bicycle
handle bars, bicycle front forks, bicycle disc brakes and bicycle wheels,
protective gear for,
e.g., hockey and motorsports such as helmets, shin guards, elbow pads,
shoulder pads, knee
pads, to name a few. Similarly, aerospace and defense fiber reinforced
composite
components, construction equipment and the like may benefit from the
application of the
protective sheath disclosed herein.
Definitions
[0050] The following definitions apply to some of the features described with
respect to
some embodiments of the invention. These definitions may likewise be expanded
upon
herein.
[0051] As used herein, the singular temis -a," "an," and "the" include plural
referents unless
the context clearly dictates otherwise. Thus, for example, a reference to an
object can include
multiple objects unless the context clearly dictates otherwise.
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100521 As used herein, the term "adjacent" refers to being near or adjoining.
Objects that
are adjacent can be spaced apart from one another or can be in actual or
direct contact with
one another. In some instances, objects that are adjacent can be coupled to
one another or can
be formed integrally with one another.
100531 As used herein, the terms "integral" and "integrally" refer to a non-
discrete portion
of an object. Thus, for example, a hockey stick including a shaft portion and
a blade portion
that is formed integrally with the shaft portion can refer to an
implementation of the hockey
stick in which the shaft portion and the blade portion are formed as a
monolithic unit. An
integrally formed portion of an object can differ from one that is coupled to
the object, since
the integrally formed portion of the object typically does not form an
interface with a
remaining portion of the object.
100541 As used herein, the term "shaft" or "shalt portion- refers to a long,
slender, and
comparatively straight member or handle on various sporting goods, instruments
and tools
such as hockey and lacrosse sticks, golf clubs and hammers.
100551 As used herein, the term "layer" refers to an individual layer which,
in the case of a
"layer of high ductility" has or all have an elongation to failure of >10% as
measured in
conformance with ASTM E8 using a specimen thickness greater than 0.3mm or in
the case of
a "layer of low ductility" has or all have an elongation to failure of <10% as
measured in
conformance with ASTM E8 using a specimen thickness greater than 0.3mm.
100561 As used herein, the term "metallic coating" or "metallic layer" means a
metallic
deposit/layer applied to part of or the entire exposed surface of an article.
The substantially
porosity-free metallic coating is intended to adhere to the surface of a
substrate to provide
mechanical strength, wear resistance, corrosion resistance, and a low
coefficient of friction.
100571 As used herein the term "laminate" or "nanolaminate" means a metallic
material that
includes a plurality of adjacent "sublayers" each having an individual
thickness between 2nm
and 250nm. A "sublayer" of a laminate or nanolaminate means a single thickness
of a
substance where the substance may be defined by a distinct composition,
microstructure,
phase, grain size, physical property such as ductility, chemical property or
combinations
thereof. It should be appreciated that the interface between adjacent layers
may not be
necessarily discrete but may be blended, i.e., the adjacent layers may
gradually transition
from one of the adjacent layers to the other of the adjacent layers.
100581 As used herein the term "graded material" means a material having at
least one
property in the deposition direction modified by at least 5%.
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[0059] As used herein the telin "compositionally modulated material" means a
material
whose chemical composition is continuously, periodically or abruptly altered
in the
deposition direction.
[0060] As used herein the term "average thickness" or "average coating/layer
thickness" is
the arithmetic average of the applied layer thickness as determined, e.g., by
the total weight
of the layer/coating applied, its density and the surface area of the
layer/coating and refers to
depth of a layer in a deposit direction.
[0061] As used herein the term "directions" refers to the three dimensional
Cartesian
coordinate system defining the three physical directions/dimensions of space -
length, width,
and height which are perpendicular to each other. The depth or height of a
deposited layer is
defined by the deposition direction as indicated hereinafter and indicates the
thickness of the
deposit layer. Length and width directions are perpendicular to the depth or
height direction.
If a substrate to be plated is a plate, line-of-sight deposits occur
perpendicular to the plate in
the height direction defining the thickness of the deposit layer. If a
substrate to be plated is
cylindrical in shape such as a tube the length is the axial direction and
deposition occurs in
radial direction.
100621 As used herein the term "chemical composition" means the chemical
composition of
a layer or structure.
100631 As used herein, the term "microstructure" refers to a microscopic
configuration of a
material. The microstructure can be crystalline, i.e., composed of grains,
amorphous, i.e., a
glassy structure without grains, or combinations, i.e., amorphous sections
embedded in
crystalline sections or vice versa. In the case of metallic materials
crystalline microstructures
can be coarse-grained (average grain-size >51.1m) or grain-refined (average
grain-size <51.1m).
100641 As used herein, the term "grain size" refers to a size of a set of
constituents such as
crystallites/grains forming the microstructure of a material, such as a grain-
refined material.
When referring to a material as being "fine-grained" or "grain-refined", it is
contemplated
that the material can have an average grain size in the submicron range, such
as in the nm
range.
[0065] As used herein, the term "ductile" is a material property that allows a
material to be
stretched or otherwise changed in shape without breaking and to retain the
changed shape
after the load has been removed. The ductility of a material such as a metal
or polymer is
reported in percent elongation to failure and can be determined from a stress-
strain curve
obtained from a tensile test. For the purpose of the present invention
materials with high
12
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ductility are defined as having a percent elongation to failure of over 10%,
preferably at least
15%, whereas materials with low ductility are defined as having a percent
elongation to
failure of no more than 10%, typically <7.5%. For the purpose of this
invention the ductility
values of metallic materials are determined by measuring bulk material
specimens greater
than 0.3mm in thickness in conformance with ASTM E8 or a similar accepted
tensile test
specification. Ductility values of polymeric materials are determined by,
e.g., ASTM D412-
06a or ASTM D624-00. Ductility values of fiber reinforced composites are
determined by,
e.g., ASTM D7205.
[0066] As used herein the term -stress-strain curve" refers to a curve
generated during
tensile testing of a material sample and the "stress-strain curve" is a
graphical representation
of the relationship between the applied stress, derived from measuring the
load applied on the
sample, and the strain, derived from measuring the deformation of the sample,
i.e., the
elongation, compression, or distortion.
100671 As used herein the term "elastomer" or -elastomeric material" is a
polymeric
material exhibiting viscoelasticity, characterized by a low Young's modulus
and high ductility
(failure strain >>100%). The term, which is derived from elastic polymer, is
often used
interchangeably with the term rubber. Elastomers usually have an amorphous
microstructure
and exist above their glass transition temperature, so that considerable
segmental motion is
possible. Elastomers are soft and readily deformable. Elastomers are usually
thermosets
(requiring vulcanization) but may also be thermoplastics.
Fiber Reinforced Polymer Composites
[0068] Fiber-reinforced polymers (FRP) are composite materials comprising a
polymer
matrix reinforced with fibers. The fibers are usually composed of glass,
carbon/graphite, or
aramid, although other fibers such as metal fibers or metal coated carbon
fibers can be used.
The polymer is usually an epoxy, vinylester or polyester thermosetting
plastic, and/or phenol
formaldehyde resin. FRPs are commonly used in the sporting goods-, aerospace-,
automotive-
, marine-, and construction-industry and are readily available commercially
from a variety of
vendors.
[0069] Fiber-reinforced polymers exhibit limited ductility and the failure
strain ductility is
typically in the range of 1-3% as deteimined by, e.g., ASTM D7205. The
inventive protective
sheath is particularly suited to overcome the shortcomings of articles,
including, but not
limited to, sports articles made from fiber reinforced composite materials.
13
CA 02861583 2014-09-03
Elastomers/Elastomeric Materials
[0070] Suitable elastomeric materials are electrically non-conductive and
comprise one or
more materials selected from the group consisting of thermoset elastomers,
thermoplastic
elastomers, thermoset elastomeric urethanes, thermoplastic polyurethanes,
thermoset
elastomeric dicyclopentadienes, elastomeric urethanes, silicones, rubbers,
polyisoprenes,
polybutadienes, polyisobutylenes and latex based materials and are readily
available
commercially from a variety of vendors. Elastomeric material layers, e.g.,
rubber toughened
epoxy compositions containing at least 10% rubber, are typically cured at
elevated
temperatures (up to 150 C) which can occur within the molding tooling or
thereafter.
[0071] Elastomers exhibit significant ductility and the failure strain
ductility is typically
>10%, typically >25%, more typically >100% and as high as 800% as measured by
ASTM
D412-06a or ASTM D624-00.
Metallic Materials
[0072] For the purpose of this invention suitable metallic materials include
highly ductile
metals and alloys (>10% elongation to failure) and metallic materials of
limited ductility
(<10% elongation).
[0073] Poorly ductile metallic materials in this context can include selected
grain-refined
and amorphous metallic materials with a ductility in the range of <1 to 10%,
typically <7.5%.
[0074] Poorly ductile metallic materials include amorphous Ni-P based alloys
which are
conveniently applied by, e.g., electroless deposition processes available from
a number of
commercial vendors which range in ductility between 0.1 and 2.5%. A number of
Ni-based or
Cu-based poorly ductile coatings can be deposited using an electroless plating
process and
are used for metallizing non-conductive substrate to render them suitable for
electroplating.
[0075] Metallizing layers which are ductile include, among other, Ag and Cu
based
electroless coatings which can be applied by an immersion, painting or
spraying process.
[0076] Preferred metallic materials include grain-refined materials although
coarse-grained
metallic materials can be used as well. Preferred grain-refined metallic
materials include: (1)
metals selected from the group of Co, Cu, Fe and Ni; (2) alloys formed of two
or more of
these metals; and (3) metal alloys formed of these metals along with an
alloying component
selected from the group of B, C, Mo, P, S, Si, and W. In some instances, a
grain-refined
material can be formed as a metal matrix composite in which a metal or a metal
alloy forms a
14
CA 02861583 2014-09-03
matrix within which a set of additives are dispersed. Particularly useful
additives include
particulate additives formed of metal oxides, nitrides of Al, B, Sc, Si and
Ti; carbides of B,
Bi, Cr, Si, and W, C such as in the form of graphite, diamond, and nanotubes,
and polymers.
Suitable particulate additives have an average particle size <251am,
preferably <10p.im, more
preferably <11A111, and even more preferably <0.4im. Depending on specific
characteristics
that are desired, the particulate additives comprise <50% by volume, such as 5-
25% by
volume.
100771 The person skilled in the art will know that the ductility of metallic
materials is not
an inherent material property and can be adjusted by various means such as the
method of
synthesis, microstructure, mechanical deformation, heat treatment, etc., and,
in the case of
thin layers, depends on the thickness of the layer tested, with thicker layers
usually showing
higher ductility values. Furthermore changing the composition by even adding
minor alloying
elements can have a drastic effect on the ductility/elongation as is well
known for iron which
can range in ductility between 0.5 and 30%. Similar rules apply to other
metals and alloys. As
another example, the ductility of pure Ni or pure Cu has been reported to
range from about
0.5% to about 60%, specifically to pure Ni or Cu prepared by
electrodeposition, the ductility
has been reported to range from as low as 0.5% to as high as 30%. Ni or Cu
based metallic
materials prepared by electrodeposition are therefore particularly suited for
practicing the
present invention as they can be formed to have high or low ductility, as
desired. Ni or Cu
layers, depending on the specific design requirements, can be very ductile and
relatively soft,
i.e., having a ductility of >10% or, alternatively, exhibit low ductility but
with increased yield
strength.
[0078] Electrodeposition is a particularly well suited process for forming
selected layers of
the protective sheath by providing the flexibility to plate layers of high or
low ductility, as
desired, build up the desired layer thickness, and grade and/or layer the
deposits
appropriately, as required. In addition, laminates or nanolaminates, defined
as having a
sublayer thickness of <250nm and as small as <100nm, can be conveniently
prepared using
electroplating techniques as well. It is known that mechanical properties of
structures such as
yield strength, hardness, modulus of elasticity and ductility can be
controlled by controlling
the thickness and/or the composition and/or the microstructure of the metallic
layers.
[0079] An example for using electrodeposition for forming one or more metallic
layers of
the protective sheath comprises plating Cu and/or Ni-based layers out of a
single plating bath
by suitably adjusting the electrical plating conditions. At very low average
current densities
CA 02861583 2014-09-03
mainly Cu rich layers are deposited, at medium average current densities Ni-Cu
alloys are
deposited, while at high average current densities mainly Ni rich layers are
deposited.
Adding, e.g., forward and/or reverse pulsing to the electrical waveform, the
strength and
ductility of each layer can be tuned even further to achieve the desired
mechanical properties.
Using this approach, e.g., ductile Cu followed by high-strength Ni layers can
be formed in a
single plating cell. Furthermore "compositionally or ductility modulated-
layers and/or
nanolaminates can be formed. In addition, Cu-rich and/or Ni-rich Ni-Cu alloy
layers with the
desired mechanical properties can be conveniently fon-ned in a single plating
cell
economically and at high production speeds. Similar rules apply to many more
binary
systems, including Cu-Co, Ni-Co, Ni-Fe, and Co-Fe systems.
Sports Articles comprising the Protective Sheath
[0080] FIG. 1 illustrates an exemplary sports article 10 implemented in
accordance with an
embodiment of the present invention. FIG. 1 depicts a frontal view of a right-
handed ice
hockey stick 10. A mirror image of the hockey stick 10 would constitute a left-
handed
embodiment.
[0081] The hockey stick 10 comprises a shaft or shaft portion 100 and a blade
or blade
portion 200. The shaft 100 and blade 200 can be integrally formed,
conventionally referred to
as a "one-piece hockey stick" or, the shaft and blade can be formed
separately, referred to as
a "two-piece hockey stick".
[0082] The shaft 100 at its lower end 102, also termed its proximal end, is
joined to the
blade 200, and the opposite distal end 104, also termed its grip end, provides
for the
grip/handle. In this embodiment, the shaft 100 has a rectangular cross-section
with the
rectangle typically having rounded corners, and having a rear face 106,
opposite a front face
108, and a top face 110 opposite a bottom face 112. Shafts can also have
different shaped
cross-sections.
[0083] The blade 200 has a blade body 202, a neck 203, a heel 204 and a toe
206. The blade
200 has a rectangular cross-section with rounded edges, having a front face
208, a rear face
210 opposite the front face 208, a top face 212 and a bottom face 214. The
inventive
protective sheath reinforcement 220 covers at least part of the blade 200 and
at least part of
the shaft 100, preferably up to IA or 1/2 of the length of the shaft 100. The
protective sheath
220 preferably forms a continuous outer face, i.e., it covers and encapsulates
the entire blade
200 and the entire circumference of the shaft 100 up to a designated outer
length of the shaft
past an edge of the proximal end 102, if any, between the blade 200 and the
shaft 100, to
16
CA 02861583 2014-09-03
cover the entire "slash zone" which according to one aspect can extend to
about half way up
the outer length of the shaft to 222. Optionally, a polymeric layer such as an
elastomeric layer
230 is applied to at least part of a puck striking surface such as the blade
front face and/or
rear face to resist slippage of the puck on the blade and improve puck
trajectory, speed and
shot accuracy.
[0084] While FIG. 1 shows one preferred embodiment, the present invention also
includes
sport articles, such as hockey sticks, where the blades are partly covered or
not covered with
the protective sheath. In addition, the present invention applies to shafts
for sport articles
(e.g., hockey sticks, lacrosse sticks and the like) where the protective
sheath covers between
and 100% of an outer length of the shaft, including up to 25% of the outer
length of the
shaft, up to 50% of the outer length if the shaft, up to 75% of the outer
length of the shaft, and
up to 100% of the outer length of the shaft. The protective sheath can be
continuous or
discontinuous, i.e., only the edges of the shaft can be covered by the
protective sheath or the
protective sheath forms a regular or irregular pattern with up to 25% of the
outer surface area
of the shaft, or up to 50% of the outer area of the shaft or even up to 75% of
the outer area of
the shaft being covered by the protective sheath.
[0085] Sport articles (e.g., hockey sticks) of the present invention may be
made of any
suitable conventional construction using natural materials (wood), synthetic
materials
(polymers) or combinations (laminated wood). In this embodiment, the hockey
stick 10 is
made of a carbon fiber reinforced polymer (CFRP) composite and the shaft 100
is hollow
whereas the blade 200 is made of a solid construction but containing foam
inserts. Other
suitable fiber reinforced materials include glass fibers and/or aramid-based
fibers. FIG. 1
depicts a hockey stick for a defense or attacking player, however, goalie
sticks, too, are
within the scope of the invention. The person skilled in the art will
appreciate that goalie
sticks are typically longer and heavier than hockey sticks for open-ice
players, contain a
paddle and have a wider and longer blade. In this case at least part of the
paddle, preferably
the entire paddle is included in the protective sheath. Dimensions of the
hockey sticks are
typically governed by the various game associations' regulatory bodies, e.g.,
the National
Hockey League (NHL).
[0086] As indicated, the basic sports article providing the substrate for the
exemplary
protective sheath can be formed of any suitable materials such as fibrous
materials, ceramics,
metals, metal alloys, polymers, or composites.
100871 The use of specific materials and other specific implementation
features of the
protective sheath can further enhance performance characteristics of the
article. For example,
17
CA 02861583 2014-09-03
the overall thickness and thickness distribution of the protective sheath can
contribute to the
performance characteristics but also add to the overall weight. It is
contemplated that the
protective sheath is applied so as to selectively cover those portions of the
sports article that
are likely to come into contact with a ball/puck, the playing surface or
another stick during
use, thus providing an improved hitting surface. It is also contemplated that
the protective
sheath can be distributed so as to selectively cover those portions of the
sports article that are
likely to come into contact with a player's hands during use, such as the
handle portion
and/or those portions likely coming into contact with another player's sports
article. It is also
contemplated that the protective sheath can be distributed so as to
selectively cover the edges
of the sports article prone to abuse with much less or no coverage in the
sections not prone to
failure such as the puck striking surface of the blade and the fairly flat
front and rear faces of
the shaft.
[0088] The use of specific materials, their respective weights and thicknesses
and other
specific implementation features, can further enhance performance
characteristics of the
sports article. In order to minimize the weight, e.g., the blade may only be
coated around the
periphery such as from the heel, around the bottom face, around the toe and
all the way
around to the top face between about 1/4 to 1" wide without having a metallic
coating in the
center portion/main puck striking area. Alternatively, the coating thickness
in less critical
areas can simply be reduced significantly, e.g., to less than 1/2 or even less
than 'A of the
thickness of the areas prone to failure, and the entire blade and slash zone
of the hockey stick
can be encapsulated.
[0089] The use of the protective sheath can allow the sports article to
exhibit improved
performance characteristics, such as a desired weight, enhanced balance,
enhanced durability,
and enhanced coupling strength to the stick portion. Also, the use of the
protective sheath can
alter a vibrational frequency response of the sports article, thus providing a
desired feel upon
impact with a ball or puck.
Implementations of the Protective Sheath
[0090] In one preferred embodiment, the sports article receiving the
protective sheath is a
hockey stick comprising a shaft and a blade made of a reinforced composite.
The reinforcing
material preferably is carbon/graphite fiber, however additions and/or
substitutions with glass
fiber and Kevlar0 fibers are within the scope of the invention. For open-ice
players the shaft
of the hockey stick is about 60" long and the slash zone extends about half
way up (about
30") the outer length of the shaft from the blade connection. The CFRP hockey
stick forming
18
CA 02861583 2014-09-03
the "substrate" has a weight of about 420g, qualifying it as a "lightweight
hockey stick". The
CFRP hockey stick has an elongation to failure of about 2% as measured by 3-
point bending,
similar fiber reinforced hockey sticks range in elongation to failure between
1 and 5%.
100911 In preparation for applying the inventive protective sheath the outer
surface of the
hockey stick blade (e.g., the entire outer surface) all the way up to the end
of the slash zone is
mechanically abraded to 500 grid equivalent or a surface roughness Ra of
<0.111m. After
degreasing a first ductile elastomeric layer comprising polyisoprene, such as
suitable rubber
toughened epoxy compositions, is applied in one or more applications such as
spraying,
painting or dipping to achieve an average elastomeric layer thickness after
curing of between
25 and 150)1m, preferably between 50-1001.1m. The ductility of the elastomeric
layer is >10%,
preferably >25% and as high as >100%. After curing, the ductile elastomeric
layer,
comprising at least 10% by weight of polyisoprene, preferably fully
encapsulates the blade
and slash zone of the shaft and has a surface roughness Rõ of between 2.5-
151.im.
Subsequently the first elastomeric layer is suitably activated by various
swelling and/or
etching treatments to receive a second layer, specifically a layer of low
ductility, such as a
brittle metallic layer, e.g., by suitably applying a metallizing layer of an
amorphous Ni-based
alloy, e.g., Ni with 3-15%P. The non-ductile average layer thickness is
typically <101.1m,
preferably between 0.5-and Simi, and more preferably between 1-and 2vtin and
has a ductility
of <2%. Optionally, the puck striking surface in the center of the blade on
the front face
and/or rear face may not be metallized if it is not to be plated subsequently,
to minimize the
added weight.
[0092] Thereafter a third layer, specifically a ductile metallic layer, is
applied to the second
layer, e.g., by electrodeposition. A suitable ductile metallic layer comprises
pure Cu or a Cu
rich alloy having an average layer thickness between 0.5 and 40vim, preferably
between 0.5
and 25 finl, more preferably between 0.75-and 12.4m, and a ductility >10%,
preferably
>15%. Areas not previously metallized lack sufficient conductivity and
therefore do not
receive an electrodeposited coating. Alternatively areas not to be plated can
be masked, as
needed.
[0093] Thereafter a fourth layer, specifically a relatively strong metallic
layer of limited
ductility is applied to the third layer, e.g., by electrodeposition. The
strong layer can
preferably comprise grain-refined metallic materials, e.g., Ni-based layers,
such as Ni with
10-50%Co or Ni-low P (0.1-3%) or Ni-Fe based layers, as well as Co-low P (0.1-
3%) or Co-
Fe layers, or Ni-Co-Fe, or Ni-Co-Fe-low P (0.1-3%) layers, or Ni-Cu layers
having an
19
CA 02861583 2014-09-03
average grain size in the range of 2-100nm, preferably between 5 and 50nm. The
average
thickness of the grain-refined layer is typically between 20 and 100 m,
preferably between
30 and 75pm, and has a ductility between 1 and 10%, preferably between 2.5 and
7.5%.
Preferably the thickness of the strong metallic layer at the bottom face of
the blade contacting
the playing surface is about 50% thicker than the average thickness of the
coating, i.e., in the
case of an overall strong metallic layer average thickness of 40 microns, the
bottom face of
the blade contacting the playing surface is increased to between 60 and 75m.
The use of
other grain-refined and/or amorphous strong metallic layers is contemplated as
well, provided
the hardness of the layer ranges between 250 and 750VHN, a minimum yield
strength
according to ASTM E8 is 600MPa, preferably 900MPa, the maximum yield strength
is
2,000MPa, preferably 2,500MPa, and the minimum Young's modulus according to
ASTM
E8 is 75MPa, preferably 1 OOMPa, and the maximum Young's modulus is 250GPa,
preferably
500GPa.
[0094] The total thickness of the protective sheath applied to the sports
article (e.g., hockey
stick) is in the range of 50 to 3501.im, preferably in the range of 100 to 250
m and the added
weight between 20 and 40g and the surface roughness Rõ of the protective
sheath outermost
layer is between 2.5-15 m. The elastomeric layer and the strong metallic layer
of low
ductility preferably are the two thickest layers applied. The elastomeric
layer typically is the
layer of the highest overall thickness and is about as thick as all metallic
layers combined.
The relatively strong layer typically represents the metallic layer of the
highest thickness.
[0095] Optionally a fifth layer is applied to the fourth layer, which can be
another ductile
elastomeric layer with the same or similar properties and dimensions as the
first layer. The
fifth layer preferably is only applied to the blade itself, specifically to
part or all of the blade
front face and/or rear face specifically designed to predominantly handle and
shoot the puck
as illustrated in FIG. I, although other shapes as depicted in the figure are
within the scope of
the invention.
[0096] Additional decorative layers can be applied to the protective sheath
such as suitable
decals, a clear coat etc. remaining within the scope of the invention as long
as they are <10%
of the total thickness of the protective sheath.
[0097] The description above for forming the exemplary protective sheath on a
substrate of
a sports article (e.g., hockey stick)is not meant to be limiting and the
person skilled in the art
will appreciate that the exemplary protective sheath can be applied by other
means. For
instance, the protective sheath can be formed from the outside in instead of
the inside out,
CA 02861583 2014-09-03
e.g., by starting out with the metallic layer and, e.g., applying the adhesive
elastomeric layer
to a metallic layer.
100981 The inventors have surprisingly discovered that the addition of a
protective sheath
with at least two, but preferably with at least three, four or five layers as
described applied to
a CFRP substrate of a hockey stick with a total added weight of between 10 and
50g,
preferably between 20 and 40g, provides a good balance between weight and
durability with
much enhanced fatigue life after impact. It has also surprisingly been found
that the sequence
of the layers is important and the durability of hockey sticks, for example,
of equivalent
weight comprising alternating layers of ductile and brittle materials is
superior to hockey
sticks containing identical layers in a different sequence or without
regularity, i.e., applying a
ductile layer on another ductile layer or a strong, relatively brittle layer
on another strong,
relatively brittle layer. For open ice players it is typically advantageous to
have the strong
layer of low ductility as the outermost functional layer (not considering thin
decorative
finishing layers) although a further polymeric insert of high ductility on the
blade may
provide for better puck control, or the designated puck striking area may not
be metal coated
at all to minimize the added weight, as described. In the case of a goalie
stick it has been
found to be advantageous to have a relatively thick elastomeric layer as the
most outer
functional layer (not considering thin decorative finishing layers) on one or
both faces of the
blade, particularly the rear face of the blade. Applying a thick ductile layer
to the entire
paddle of the goalie stick which, in the NHL, typically has a maximum length
of 26 inches,
can assist in limiting the puck rebound distance.
100991 A further advantage of the inventive protective sheath is that it can
be either readily
added to the existing reinforced hockey stick manufacturing process or
conveniently added
later as a retrofit. Layer properties, sequence and thicknesses can also be
easily adjusted to
meet players' personal preferences.
1001001 As an example, the peak load to failure of various carbon fiber
reinforced hockey
sticks with and without the exemplary protective sheath was investigated. The
protective
sheath comprised a 751.1m 33% polyisoprene containing elastomeric layer
vulcanized at
140 C and built up to thickness with two applications, a 1.5vtm thick
metallizing layer of low
ductility amorphous Ni-7P, a 10pm layer of ductile electrolytic Cu and a
501..tm strong grain-
refined layer of Ni-30Co as indicated in Table 1. The shafts were securely
mounted on two
locations 50cm (19.7") apart and the three-point flexure strength to failure
expressed in
Newtons was determined by applying a load using an Instron Universal Tester
unit half way
21
CA 02861583 2014-09-03
between the mounting locations on the wider side of the hockey stick (about 1"
wide front
face; 108 in FIG. 1) using a 1/2.- diameter load element. The peak load at
failure was recorded.
"New" hockey sticks and hockey sticks having been subjected to an impact load
of 15 Joules
with a 1/2" diameter load element were tested. To simulate impact damage,
hockey sticks were
securely mounted in the same jig but with the narrow side (the top face 110 in
FIG. 1, which
is about 3/4") positioned upward and weights were dropped on them half way
between the
mounting locations to achieve an impact force of 15J. This experiment
simulated a stick-on-
stick impact occurring most likely on the narrow top face of the shaft, while
breakage would
most likely occur when shooting the puck on the wider front face, i.e.,
perpendicular to the
initial impact. Five (5) specimens for each condition were tested. Table 1
indicates that the
hockey sticks having the exemplary protective sheath retained a much greater
percentage of
the original load bearing capacity performance after impact. In addition, the
shaft peak load
after impact for the hockey stick having the exemplary protective sheath
exceeded the
performance of the bare hockey shafts before impact. Normalized for weight and
length the
shafts having the inventive protective sheath after impact had an average peak
load value of
682N.cm/g versus 602N.cm/g for the bare shafts after impact.
[00101] The inventors have discovered that, in order for the protective sheath
to provide a
meaningful improvement, at least one polymeric layer and at least one metallic
layer,
specifically the strong metallic layer of limited ductility, need to be
present. Furthermore,
adding one or more metallic layers directly to the FRP substrate of the hockey
stick does not
provide a substantial performance benefit without the application of a
polymeric layer in
between the CFRP substrate and the strong metallic layer and therefore appears
to add weight
without appreciable performance benefits. Similarly, a sequence of, e.g.,
various layers of
low ductility without the application of a subsequent ductile layer of at
least 10um thickness
in between appears to add weight without appreciable performance benefits.
From the above
the person skilled in the art will understand how to apply the guidance
hereinbefore described
to assemble a protective sheath according to the present invention meeting the
desired
performance benefits for specific applications.
[00102] Table 1: Peak Load of various Hockey Sticks Before and After Impact.
Peak Load New Peak Load after Loss of
Hockey Stick ID
[N] Impact [N]
Performance [%]
Bare Hockey Shaft (prior art) 1734 1172 32.4
22
CA 02861583 2014-09-03
Hockey Shaft with 4 Layer 2056 1767 14.1
Protective Sheath (this invention)
[00103] It is contemplated that each layer of high or low ductility can be
formed so as to
include two or more sub-layers, which can be formed of the same material or
different
materials within the thickness range provided. For certain implementations, at
least one of the
sub-layers can be formed of a conductive material, such as in the form of a
coating of a metal,
or a non-conductive material.
[00104] As illustrated, one preferred embodiment provides a protective sheath
comprising a
total of four layers, i.e., two sets of layers alternating between low
ductility and high ductility.
According to another embodiment of the invention a multi-layered design
includes a first
elastomeric layer, and a second high strength, metallic layer of low ductility
that is adjacent
to the first layer. According to another embodiment of the invention a multi-
layered design
includes a first elastomeric layer, and a low ductility metallic layer that is
adjacent to the first
layer, and a third layer that is adjacent to the second layer comprising a
high ductility metallic
layer. According to another embodiment of the invention a multi-layered design
includes a
first elastomeric layer, a second layer which is a metallic layer of low
ductility that is
adjacent to the first layer, a third layer which is a metallic layer of high
ductility that is
adjacent to the second layer, and a fourth layer which is a metallic layer of
low ductility that
is adjacent to the third layer. It is also contemplated that the protective
sheath can include
more or less layers for other implementations.
[00105] In another test new, partially coated hockey sticks (e.g.,
approximately 23" from the
heel 204 of the blade 200, average total weight of 490g) and new, uncoated
hockey sticks
(average total weight of 419g) were subjected to three point bend tests over
lm (40") of the
shafts, extending from the heels upwards. The shafts were designed to have the
same flex and
the test location was approximately 21" from the heel. The load was applied to
the front face
208 of the blade 200 of each of the hockey sticks. Table 2 indicates that the
hockey sticks
having the exemplary protective sheaths provided a 30% increase in load to
failure and a
16.5% increase in deflection to failure.
[00106] Table 2: Peak Load of various Unused Hockey Sticks.
Peak Load Difference Deflection at
Difference
Hockey Stick ID
New [N] [0/0] Failure [mm] [%]
Bare Hockey Shaft (prior art) 1134.7 85.7
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CA 02861583 2014-09-03
Hockey Shaft with 4 Layer
Protective Sheath (this 1476.7 +30.1 99.8 +16.5
invention)
1001071 Determining the area under the stress-strain curves indicated that, at
their respective
failures, the inventive shafts stored 51% more energy than the uncoated
shafts.
[00108] Similar results are obtained when the exemplary articles are lacrosse
sticks,
aerospace parts, and the like.
1001091 The foregoing description of the invention has been presented
describing certain
operable and preferred embodiments. It is not intended that the invention
should be so limited
since variations and modifications thereof will be obvious to those skilled in
the art, all of
which are within the spirit and scope of the invention.
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