U.S. patent application number 14/475613 was filed with the patent office on 2015-03-12 for article with protective sheath.
The applicant listed for this patent is Integran Technologies Inc.. Invention is credited to Iain Brooks, Dave Limoges, Gino Palumbo, Konstantinos Panagiotopoulos, Andrew J. Robertson, Klaus Tomantschger.
Application Number | 20150072809 14/475613 |
Document ID | / |
Family ID | 52626123 |
Filed Date | 2015-03-12 |
United States Patent
Application |
20150072809 |
Kind Code |
A1 |
Palumbo; Gino ; et
al. |
March 12, 2015 |
ARTICLE WITH PROTECTIVE SHEATH
Abstract
Protective sheaths particularly for fiber reinforced articles
comprising a combination of polymeric and metallic material layers,
are disclosed. The protective sheaths comprise alternating layers
of high and low ductility and are particularly suited for sports
articles, such as hockey sticks, lacrosse sticks, baseball/softball
bats and golf clubs.
Inventors: |
Palumbo; Gino; (Toronto,
CA) ; Brooks; Iain; (Toronto, CA) ;
Tomantschger; Klaus; (Mississauga, CA) ; Robertson;
Andrew J.; (Toronto, CA) ; Panagiotopoulos;
Konstantinos; (Etobicoke, CA) ; Limoges; Dave;
(Toronto, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Integran Technologies Inc. |
Mississauga |
|
CA |
|
|
Family ID: |
52626123 |
Appl. No.: |
14/475613 |
Filed: |
September 3, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61875144 |
Sep 9, 2013 |
|
|
|
Current U.S.
Class: |
473/560 |
Current CPC
Class: |
A63B 2102/22 20151001;
A63B 2102/24 20151001; A63B 60/00 20151001; A63B 60/54 20151001;
A63B 59/70 20151001 |
Class at
Publication: |
473/560 |
International
Class: |
A63B 59/14 20060101
A63B059/14 |
Claims
1. A hockey stick comprising: a shaft portion comprising fiber
reinforced composite materials, said shaft portion including a grip
end and a proximal end, and a blade portion connected to the
proximal end of the shaft portion; and a protective sheath covering
at least the proximal end 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 in a depth
direction of said protective sheath, each having a thickness
between 0.25 and 150 .mu.m; 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 shaft portion followed by at least one metallic layer having an
elongation to failure of .ltoreq.10%.
2. The hockey stick of claim 1, wherein said polymer layer has an
elongation to failure of .gtoreq.15% according to ASTM D412-06a, a
thickness of between 50 and 100 .mu.m and comprises an elastomeric
material.
3. The hockey stick of claim 2, wherein said elastomeric material
comprises at least one material selected from the group consisting
of thermoset elastomer, thermoplastic elastomer, thermoset
elastomeric urethane, thermoplastic polyurethane, thermoset
elastomeric dicyclopentadiene, elastomeric urethane, silicone,
rubber, polyisoprene, polybutadiene, polyisobutylene, latex and
rubber toughened epoxy compositions.
4. The hockey stick of claim 1, wherein said metallic layer has a
thickness of between 20 and 100 .mu.m and a minimum yield strength
according to ASTM E8 of 600 MPa.
5. The hockey stick of claim 4, wherein said metallic layer has an
average grain size in the range of 2 nm to 5,000 nm, a hardness in
the range of 300 Vickers to 1,000 Vickers and includes at least one
element selected from the group consisting of Co, Cu, Fe, Ni and
P.
6. The hockey stick of claim 5, wherein said metallic layer has an
average grain size between 2 and 100 nm.
7. The hockey stick of claim 1 wherein said protective sheath
comprises at least three layers alternating in ductility between
.ltoreq.10% and >10%.
8. The hockey stick of claim 1, wherein at least outer edges of the
blade portion are covered by said protective sheath.
9. A hockey stick comprising: a shaft portion including a 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 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 R.sub.a
in the range of 2.5 to 15 .mu.m and representing between 3 and 50%
of the total overall weight of the hockey stick; said protective
sheath being composed of a multi-layer structure containing at
least four layers each having a thickness between 0.25 and 150
.mu.m; said multi-layer structure comprising a polymer first layer
having an elongation to failure of >10% in intimate contact with
the fiber reinforced composite material of the hockey stick
followed by a metallic second layer having an elongation to failure
of .ltoreq.10%; followed by a metallic third layer having an
elongation to failure of >10%; followed by a metallic fourth
layer having an elongation to failure of .ltoreq.10% and a minimum
yield strength according to ASTM E8 of 600 MPa.
10. The hockey stick of claim 9, wherein said polymer first layer
comprises an elastomeric material having an elongation to failure
of >10% and a thickness of between 50 and 100 .mu.m, said
metallic second layer having a thickness of between 0.25 and 5
.mu.m, said metallic third layer having an elongation to failure of
.gtoreq.15% and a thickness of between 0.5 and 25 .mu.m; and said
metallic fourth layer having a thickness of between 20 and 100
.mu.m.
11. The hockey stick of claim 10, wherein said elastomeric material
layer comprises at least one material selected from the group
consisting of thermoset elastomer, thermoplastic elastomer,
thermoset elastomeric urethane, thermoplastic polyurethane,
thermoset elastomeric dicyclopentadiene, elastomeric urethane,
silicone, rubber, polyisoprene, polybutadiene, polyisobutylene,
latex and rubber toughened epoxy compositions.
12. The hockey stick of claim 9, wherein said metallic second layer
of said protective sheath comprises an amorphous Ni alloy.
13. The hockey stick of claim 9, wherein said metallic third layer
of said protective sheath comprises at least one element selected
from the group consisting of Ag, Co, Cu, Fe, Ni and P.
14. The hockey stick of claim 9, wherein said metallic fourth layer
of said protective sheath comprises at least one element selected
from the group consisting of Co, Cu, Fe, Ni and P.
15. The hockey stick of claim 14, wherein said metallic fourth
layer comprises at least one element selected from the group of Co,
Cu, Fe, Ni and P having an average grain size that is in the range
of 2 nm to 5,000 nm, a yield strength in the range of 200 MPa to
2,750 MPa, and a hardness in the range of 300 Vickers to 1,000
Vickers.
16. The hockey stick of claim 15, wherein said metallic fourth
layer has an average grain size between 2 and 100 nm.
17. The hockey stick of claim 9, wherein said protective sheath
comprises at least five layers, wherein said fifth layer comprises
a polymer having an elongation to failure of .gtoreq.15%.
18. The hockey stick of claim 9, wherein said protective sheath has
a weight of between 20 and 50 g.
19. The hockey stick of claim 9, wherein said protective sheath
fully encapsulates at least one of the blade portion and a slash
zone defined by the proximal end of the shaft portion.
20. The hockey stick of claim 9, wherein said protective sheath has
a total thickness in the range of 50 to 350 .mu.m.
21. A hockey stick comprising: a shaft portion including a 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 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 R.sub.a
in the range of 2.5 to 15 .mu.m and representing between 3 and 50%
of the total overall weight of the hockey stick; said protective
sheath being composed of a multi-layer structure containing at
least four layers each having a thickness between 0.25 and 150
.mu.m; said multi-layer structure comprising alternating layers
having an elongation to failure of .ltoreq.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 .ltoreq.10% selected from the group of
Co, Cu, Fe and Ni having an average grain size that is in the range
of 2 nm to 5,000 nm, a yield strength in the range of 200 MPa to
2,750 MPa, and a hardness in the range of 300 Vickers to 1,000
Vickers.
22. The hockey stick of claim 20, wherein said protective sheath
has a total thickness in the range of 50 to 350 .mu.m.
23. A hockey stick comprising: a shaft portion connected to a blade
portion, said shaft portion including a grip end and a proximal
end, said shaft portion having 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 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 15 J on the top face.
24. The hockey stick of claim 23, wherein said shaft portion having
said protective sheath after impact has an average peak load value
exceeding an average peak load value on the shaft portion devoid of
said protective sheath before impact.
25. The hockey stick of claim 23, wherein said shaft portion having
said protective sheath provided at least a 30% increase in load to
failure after being subjected to three point bend tests over
approximately 1 m of said shaft portion.
26. The hockey stick of claim 23, wherein said shaft portion having
said protective sheath provided at least a 16.5% increase in
deflection to failure after being subjected to three point bend
tests over approximately 1 m of said shaft portion.
27. An article comprising: a shaft portion comprising fiber
reinforced composite materials, said shaft portion defining a 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 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 15 J impact on the top face has an average peak load
value on the front face exceeding an average peak load value on the
shaft portion devoid of said protective sheath and not subjected to
the 15 J impact.
28. The article of claim 27, wherein said protective sheath is
composed of a multi-layer structure comprising at least two layers
each having a thickness between 0.25 and 150 .mu.m; said
multi-layer structure comprising a polymer layer having an
elongation to failure of >10% and at least one metallic layer
having an elongation to failure of .ltoreq.10%.
29. The article of claim 27, wherein said article is selected from
the group consisting of a hockey stick, a lacrosse stick, a tennis
racquet, a squash racquet, a racquetball racquet and a badminton
racquet, and a golf shaft.
Description
[0001] The present application claims priority to U.S. Prov. Patent
App. Ser. No. 61/875,144, filed on Sep. 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.
[0006] 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 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.
[0009] 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 multi-layer
sheath, comprising alternating layers of highly ductile and less
ductile coatings, is applied to at least part of the outer surface
thereof.
[0011] 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 .ltoreq.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 .mu.m.
[0012] 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 150 .mu.m, preferably between 50 and 100 .mu.m,
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.
[0017] 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 250 nm, preferably between 2 and 100 nm 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.
[0020] 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 100 .mu.m applied, e.g., by
electrodeposition.
[0021] 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 2 nm to 100 nm,
preferably an average grain-size between 15 and 75 nm, 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 .ltoreq.10% elongation to failure, preferably between 2 and
7.5% elongation to failure.
[0022] 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 10 .mu.m 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%.
[0023] 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.
[0024] 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.
[0025] 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.
[0026] 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.
[0027] 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.
[0028] 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
.gtoreq.20%, preferably .gtoreq.50% when compared to the same
article without the addition of the protective sheath.
[0029] 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.
[0030] 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.
[0031] 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
MoS.sub.2 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% 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, U.S. Pat. No. 8,025,979 and U.S.
Pat. No. 7,553,553, the disclosures of which are incorporated
herein by reference in their entirety.
[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; MoS.sub.2; and organic materials such as PTFE and other
polymeric materials. The particulate average particle size is
typically below 10 .mu.m, such as below 5 .mu.m, below 1,000 nm (or
1 .mu.m), or below 500 nm.
[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:
[0038] (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
[0039] (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 150
.mu.m; said multi-layer structure comprising a polymer layer having
a bulk tensile 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 .ltoreq.10%.
[0040] Accordingly, the present invention in another embodiment is
directed to a hockey stick comprising:
[0041] (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
[0042] (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 R.sub.a in the range of 2.5 to 15 .mu.m 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 150 .mu.m;
preferably between 0.5 and 100 .mu.m, and a total overall thickness
between 50 and 250 .mu.m; preferably between 75 and 150 .mu.m, said
multi-layer structure comprising alternating layers having an
elongation to failure of .ltoreq.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 .ltoreq.10%; followed by another
metallic layer having an elongation to failure of >10%; followed
by another metallic layer having an elongation to failure of
.ltoreq.10% and a minimum yield strength according to ASTM E8 of
600 MPa.
[0043] Accordingly, the present invention in another embodiment is
directed to a hockey stick comprising:
[0044] (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
[0045] (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 R.sub.a in the range of 2.5 to 15 .mu.m 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 layers each having a thickness between
0.25 and 150 .mu.m; said multi-layer structure comprising
alternating layers having an elongation to failure of .ltoreq.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 .ltoreq.10%
selected from the group of Co, Cu, Fe and Ni having an average
grain size that is in the range of 2 nm to 5,000 nm, a yield
strength in the range of 200 MPa to 2,750 MPa, and a hardness in
the range of 300 Vickers to 1,000 Vickers.
[0046] Accordingly, the present invention in another embodiment is
directed to a hockey stick comprising:
[0047] (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
[0048] (ii) a protective sheath comprising at least one metallic
layer covering at least part of an outer length of said shaft
portion;
[0049] 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 15 J 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 50 cm apart and applying the load half way
between the mounting locations using a 1/2'' diameter load
element.
[0050] Accordingly, the present invention in another embodiment is
directed to an article comprising a shaft portion comprising a
fiber reinforced polymer:
[0051] (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
[0052] (ii) a protective sheath comprising at least one metallic
layer covering at least part of an outer length of said shaft
portion;
[0053] wherein said shaft portion having said protective sheath
after a 15 J 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 15 J impact, wherein said peak load value is determined by
securely mounting said shaft portion on two locations 50 cm apart
and applying the load or impact force half way between the mounting
locations using a 1/2'' diameter load element.
BRIEF DESCRIPTION OF THE DRAWINGS
[0054] 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.
[0055] 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
[0056] 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.
[0057] 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.
[0058] 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.degree.. 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 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.
[0059] 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.
[0060] 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).
[0061] 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
[0062] 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.
[0063] As used herein, the singular terms "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.
[0064] 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.
[0065] 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.
[0066] As used herein, the term "shaft" or "shaft 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,
[0067] 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 0.3 mm or in
the case of a "layer of low ductility" has or all have an
elongation to failure of .ltoreq.10% as measured in conformance
with ASTM E8 using a specimen thickness greater than 0.3 mm.
[0068] 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.
[0069] 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 2 nm and 250 nm. 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.
[0070] As used herein the term "graded material" means a material
having at least one property in the deposition direction modified
by at least 5%.
[0071] As used herein the term "compositionally modulated material"
means a material whose chemical composition is continuously,
periodically or abruptly altered in the deposition direction.
[0072] 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.
[0073] 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.
[0074] As used herein the term "chemical composition" means the
chemical composition of a layer or structure.
[0075] 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 >5 .mu.m) or grain-refined
(average grain-size .ltoreq.5 .mu.m).
[0076] 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.
[0077] 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
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 .ltoreq.7.5%. For the purpose of this
invention the ductility values of metallic materials are determined
by measuring bulk material specimens greater than 0.3 mm 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.
[0078] 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.
[0079] 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
[0080] 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.
[0081] Fiber-reinforced polymers exhibit limited ductility and the
failure strain ductility is typically in the range of 1-3% as
determined 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.
Elastomers/Elastomeric Materials
[0082] 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.degree. C.)
which can occur within the molding tooling or thereafter.
[0083] 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
[0084] 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
(.ltoreq.10% elongation).
[0085] 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
.ltoreq.7.5%.
[0086] 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.
[0087] 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.
[0088] 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 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 .ltoreq.25
.mu.m, preferably .ltoreq.10 .mu.m, more preferably .ltoreq.1
.mu.m, and even more preferably .ltoreq.0.5 .mu.m. Depending on
specific characteristics that are desired, the particulate
additives comprise .ltoreq.50% by volume, such as 5-25% by
volume.
[0089] 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.
[0090] 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
.ltoreq.250 nm and as small as .ltoreq.100 nm, 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.
[0091] 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 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 formed 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
[0092] 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.
[0093] 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".
[0094] 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.
[0095] 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 1/4 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 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.
[0096] 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 10 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.
[0097] 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).
[0098] 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.
[0099] The use of specific materials and other specific
implementation features of the protective sheath can further
enhance performance characteristics of the article. For example,
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.
[0100] 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 1/4 of the
thickness of the areas prone to failure, and the entire blade and
slash zone of the hockey stick can be encapsulated.
[0101] 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
[0102] 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 Kevlar.RTM. 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 the "substrate" has
a weight of about 420 g, 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%.
[0103] 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
R.sub.a of .ltoreq.0.1 .mu.m. 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 .mu.m, preferably between 50-100 .mu.m. 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 R.sub.a of between 2.5-15 .mu.m. 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 <10 .mu.m, preferably between 0.5- and 5
.mu.m, and more preferably between 1- and 2 .mu.m 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.
[0104] 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 40 .mu.m,
preferably between 0.5 and 25 .mu.m, more preferably between 0.75-
and 12.5 .mu.m, 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.
[0105] 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 average grain size in the range of 2-100 nm, preferably
between 5 and 50 nm. The average thickness of the grain-refined
layer is typically between 20 and 100 .mu.m, preferably between 30
and 75 .mu.m, 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 75
.mu.m. 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 600 MPa, preferably 900 MPa, the maximum
yield strength is 2,000 MPa, preferably 2,500 MPa, and the minimum
Young's modulus according to ASTM E8 is 75 MPa, preferably 100 MPa,
and the maximum Young's modulus is 250 GPa, preferably 500 GPa.
[0106] The total thickness of the protective sheath applied to the
sports article (e.g., hockey stick) is in the range of 50 to 350
.mu.m, preferably in the range of 100 to 250 .mu.m and the added
weight between 20 and 40 g and the surface roughness R.sub.a of the
protective sheath outermost layer is between 2.5-15 .mu.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.
[0107] 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. 1, although other shapes as depicted in the
figure are within the scope of the invention.
[0108] 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.
[0109] 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, e.g., by starting out
with the metallic layer and, e.g., applying the adhesive
elastomeric layer to a metallic layer.
[0110] 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 50 g, preferably between 20 and 40 g, 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.
[0111] 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.
[0112] 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 75 .mu.m 33% polyisoprene containing elastomeric layer vulcanized
at 140.degree. C. and built up to thickness with two applications,
a 1.5 .mu.m thick metallizing layer of low ductility amorphous
Ni-7P, a 10 .mu.m layer of ductile electrolytic Cu and a 50 .mu.m
strong grain-refined layer of Ni-30Co as indicated in Table 1. The
shafts were securely mounted on two locations 50 cm (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 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 15 J. 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 682Ncm/g versus
602Ncm/g for the bare shafts after impact.
[0113] 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 10 .mu.m 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.
TABLE-US-00001 TABLE 1 Peak Load of various Hockey Sticks Before
and After Impact. Peak Load Loss of Peak Load after Impact
Performance Hockey Stick ID New [N] [N] [%] Bare Hockey Shaft 1734
1172 32.4 (prior art) Hockey Shaft with 2056 1767 14.1 4 Layer
Protective Sheath (this invention)
[0114] 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.
[0115] 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.
[0116] In another test new, partially coated hockey sticks (e.g.,
approximately 23'' from the heel 204 of the blade 200, average
total weight of 490 g) and new, uncoated hockey sticks (average
total weight of 419 g) were subjected to three point bend tests
over 1 m (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.
TABLE-US-00002 TABLE 2 Peak Load of various Unused Hockey Sticks.
Differ- Differ- Peak Load ence Deflection at ence Hockey Stick ID
New [N] [%] Failure [mm] [%] Bare Hockey Shaft 1134.7 -- 85.7 --
(prior art) Hockey Shaft with 1476.7 +30.1 99.8 +16.5 4 Layer
Protective Sheath (this invention)
[0117] 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.
[0118] Similar results are obtained when the exemplary articles are
lacrosse sticks, aerospace parts, and the like.
[0119] 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.
* * * * *