Note: Descriptions are shown in the official language in which they were submitted.
CA 02237902 1998-0~-13
SPECIFI~ATION
SKI AND SNOWBOARD HAVING EXCELLENT GLIDING
PROPERTIES AND PROCESS FOR PRODUCING SAME
TECHNICAL FIELD
The present invention relates to skis and snowboards
which are outstanding in gliding properties and strength and
to a process for producing these articles.
BACKGROUND ART
Skiing events include races, such as a slalom and
giant slalom, competing in time of the order of 1/100 second.
In these races, the resistance of the sole providing the glide
face is of extreme importance. Immediately before skiing, a
wax is applied by ironing (so called hot wax, waxing) to the
surface of the sole which is usually made of polyethylene, and
the waxed surface is further ironed to ensure a smooth glide.
However, almost no portion of the hot wax applied by this
method penetrates into the sole, so that the sole needs to be
elaborately ironed repeatedly even when the ski is to be used
again soon after a single run, whereas the gliding properties
still remain to be improved to be satisfactory.
From this viewpoint, on the other hand, it has been
attemp~ed to obtain soles from a mixture of polyethylene and
wax by injection molding, but the polyethylene for use in
injection molding needs to have a low molecular weight. As a
result, the ski soles obtained are very low in strength, and
none of them have found actual use.
_
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An object of the invention is to provide skis and
snowboards which are excellent in gliding properties and
strength and a process for producing these articles.
DISCLOSURE OF THE INVENTION
The present invention provides a ski or snowboard
having a sole impregnated with a wax, characterized in that
the ski or snowboard has a body attached by an adhesive layer
to a wax impregnation preventing film formed over one surface
of the sole.
The invention also provides a process for producing
a ski or snowboard having a wax-impregnated sole which process
is characterized by forming a wax impregnation preventing film
over one surface of a sole for the ski or snowboard, immersing
the sole in a bath of molten wax to impregnate the sole with
the wax, withdrawing the sole from the bath, removing the wax
adhering to a surface of wax impregnation preventing film and
a glide face, and attaching the wax impreqnation preventing
film to a ski or snowboard body with an adhesive.
While the present invention relates to the
production of skis and snowboards, the glide faces of these
two types of articles are similar, so that the invention will
hereinafter be described with reference to skis for the sake
of simplicity.
The sole to be use~ in the present invention is made
from a polyethylene having a molecular weight of at least
500,000, preferably a superhigh molecular weight of 500,000 to
6,000,000, more preferably 3,000,000 to 4,000,000, whereby
sufficiently increased strength can be glven to the sole,
~ - ~ - -
CA 02237902 1998-OS-13
<
therefore, to the ski.
The wax to be used in the present invention is
preferably a mixed wax consisting primarily of n-alkanes
having a melting point of 30 to 70 ~ and 18 to 40 carbon
atoms. Examples of such waxes are PF115, PF125, PF135, HNP-11,
SP-0110, ET-0073K, etc. manufactured by Nippon Seiro Co., Ltd.
Mixtures of such a wax and other wax are of course usable
insofar as the mixture is compatible with the sole.
According to the invention, a wax impregnation
preventing film is formed over one surface of the sole, and
the sole is then immersed in a bath of the wax as melted to
impregnate the sole with the wax. Preferably, the surface of
the sole to be formed with the preventing film is treated by a
chemical or physical method in advance and thereby given an
improved adhering property. Examples of chemical methods are
treatment with a chemical such as chromium sulfate or nitric
acid, and treatment with a coupling agent. Examples of
physical methods are treatment with flames, treatment by
corona discharge, glow discharge or ultraviolet rays,
sandpapering and embossing. Examples of coupling agents are
vinyltriethoxysilane and ~ -methacryloxypropyl-
trimethoxysilane.
The wax impregnation preventing film can be formed,
f or example, ky applying to the scle an epoxy cGating
composition, urethane coating composition or acrylic coating
composition which is incompatible with the wax. The sole is
coated with the composition over the surface thereof to be
adhered to the body of the ski, for example, by a brush,
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applicator or spray. Alternatively, the preventing film may be
prepared in the form of a sheet first and then adhered to the
sole. The thickness of the preventing film is usually about 5
to about 200 ~ m, preferably about 10 to about 100 ~ m, more
preferably about 10 to about 60 J/ m. The hardness of the wax
impregnation preventing film is usually about HmV 0.3 to about
10, preferably about HmV 0.4 to about 2, more preferably about
HmV 0.5 to about 1.2, in terms of micro-Vickers hardness (JIS
Z 2244, load 10 gf, hold time 30 seconds). If the hardness is
less than 0.3, the strength of adhesion between the film and
the ski body is low, whereas when the hardness is over 10, the
preventing film is liable to develop cracks. The sole having
the wax impregnation preventing film thus ~ormed over one
surface thereof is immersed in the molten wax bath. Usually,
the wax melting temperature is preferably about 70 to about
110 ~ . The immersion time is at least 0.1 hour, preferably
about 0.1 to about 7 hours.
The sole is taken out from the wax bath, and the wax
adhering to the surface of the wax impregnation preventing
~ilm and the glide face are removed. For the removal of the
wax, a major portion of the wax is removed first by a physical
method using a plastic or rubber scraper or fabric or paper
wiper, and the remaining wax is then removed by a chemical
method using a wax remover r such as n-hexane o~ white
gasoline, which will not dissolve the adhesive.
In this way, a wax-impregnated sole can be obtained
which is excellent in gliding properties and strength and
which exhibits excellent adhesion to the body of the ski.
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The adhesive for adhering the wax impregnation
preventing film to the ski body is preferably one having
affinity for the coating composition used for forming the
preventing film. For example, an epoxy adhesive is desirable
when the epoxy coating composition is used for the preventing
film, and a urethane adhesive is preferred when the urethane
coating composition is used, although these examples are not
limitative.
According to the invention, the concentration of the
wax in the sole has such a gradient as to decrease from the
surface of the sole to the interior thereof. The average
concentration of C24Hso~ one of n-alkanes, in the sole surface
portion ranging, for example, from 0 to 100 ~ m in depth from
the surface is preferably at least about 0.1 ~ mole/cm3 as
measured by gas/mass chromatography. In this case, the sole
has a scorching time of at least 5 minutes, usually at least 7
minutes, and is fully useful for events which will be
completed within this period of time.
The object of the invention can be fully achieved
when at least the surface of the sole is impregnated with the
wax. The term the "surface" refers, for example, to the
portion of the sole ranging from 0 to 100 ~ m in depth from
the surface. Although a so-called ironing of hot wax is
unnecessary for t~le ski of the invention, this ironing is used
more preferably for the ski of the invention. Presumably
ironing permits the hot wax to penetrate deep into the sole in
a large quantity owing to the high affinity of the hot wax for
the wax impregnating the sole, consequently affording
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excellent gliding properties. The amount of the wax
impregnating the sole is dependent on the impregnation
temperature and impregnation time; the higher the temperature
and the longer the time, the greater is the amount of wax
impregnating the sole. The depth of impregnation is less
affected by the temperature; the sole can be impregnated with
the wax to a position proximate to the wax impregnation
preventing film regardless of whether the temperature is low
or high. The amount of impregnating wax is limited since an
excess of wax lowers the strength of the sole. The amount is
preferably such that the sole is at least about 80 MPa in
shearing modulus and at least about HmV 3.0 in micro-Vickers
hardness.
The amount of impregnating wax was measured by the
following method in the present invention. Preparation of
specimens
Pieces, 2x 5x 0.01 mm, were cut from the surface of
the sole using the microtome stated below, and 10 pieces (0.1
mm in thickness) were checked as a unit to quantitatively
determine the wax concentration.
Microtome:
Name supermicrotome
Model AS 500
Manufacturer Angria Scientific (Germany)
Analysis
Ten 0.01-mm-thick specimens had a combined weight of
about 1.00 + 0.3 mg.
The wax alone was selectively extracted from the
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sole by the thermal desorption method and quantitatively
determined by gas/mass chromatography (GC/MS) to obtain an
absolute amount.
Thermal desorption device:
Name Curie point-type pyrolizer
Manufacturer Nippon Bunseki Kogyo Co., Ltd.
GC/MS:
Model HP5890~ (GC), HP5971 (MS)
Manufacturer Hewlett Packard
The wax-impregnated sole of the invention is usable
for skis, for example, of the sandwich type, cap type, etc.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a graph showing amounts of C24Hso~ a
component of wax, per unit volume in the soles of Examples 1
to 6 of the invention and Comparative Example 1 at varying
depths;
FIG. 2 is a graph showing the relationship between
the friction (sliding) time and the coefficient of dynamic
friction (~ ) as established for four kinds of soles which are
different in the average concentration of wax in the surface;
and
~IG. 3 is a graph showing the gliding test results
achieved by the skis of Examples 1 to 6 and Comparative
Example l and skis not,treat~d with an~ wax for reference.
BEST MODE OF CARRYING OUT THE INVENTION
The present invention will be described in greater
detail with reference to the following examples and
comparative examples.
~ ~ ~ _
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Example 1
One surface of a ski sole (IMS Kunstoff AG, P-TEX
2000) having a thickness of 1.35 mm and made of polyethylene
having a molecular wei~ht of 3,500,000 and a density of 0.937
g/cm3 was oxidized by a gas burner and then coated with a
urethane coating composition (Kashu Co., Ltd., STRON ACE 22)
by spraying to form a wax impregnation preventing film having
a thickness of 50 + 10 ~ m and HmV 8.46 in micro-Vickers
hardness. The sole was then immersed in a bath of~molten wax
(PF125, m.p. 52.5 ~ , density 0.911 g/cm3, consisting
primarily of 15.4% of C24 Hso and 16.5% of C2 5H5 2) at 90 ~C
for 10 minutes, whereby the sole was impregnated with the wax.
The sole was taken out from the wax bath, the wax adhering to
the surface of the wax impregnation preventing film and the
glide face was removed by a scraper first, and the remaining
wax was then removed with white gasoline.
The urethane film of the wax-impregnated sole was
subsequently bonded to a ski body with an epoxy adhesive ~two
pack type, Araldite AW106 (main agent), HV953U (hardener)]. In
this way, skis of the invention were obtained. The sole was
230 MPa in shearing modulus and HmV 3.8 in micro-Vickers
hardness.
Example 2
Skis of the invention were prepared in the same
manner as in Example 1 except that the impregnation time was
60 minutes.
Example 3
Skis of the invention were prepared in the same
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manner as in Example 1 except that the impregnation
temperature was 70 ~ .
Example 4
Skis of the invention were prepared in the same
manner as in Example 1 with the exception of coating each sole
with a urethane coating composition (Origin Co., Ltd., U-03)
by spraying to form a wax impregnation preventing film having
an average thickness of 35 ~ m (HmV 0.7 in micro-Vickers
hardness) and bonding the urethane film to a ski body with an
urethane adhesive [two pack type, US100 (main agent), F-1
(hardener)] serving as an adhesive.
Example 5
Skis of the invention were prepared in the same
manner as in Example 1 with the exception of coating each sole
with an epoxy coating composition (Origin Co., Ltd., #HS N-7)
by spraying to form a wax impregnation preventing film having
an average thickness of 35 ~ m (HmV 0.4 in micro-Vickers
hardness).
Example 6
Skis of the invention were prepared in the same
manner as in Example 1 with the exception of coating each sole
with an acryl-urethane coating composition (Kashu Co., Ltd.,
STRON ACE HD2) by spraying to form a wax impregnation
preventing film having an avera~e thickness of 35 ~ m ~HmV
1.04 in micro-Vickers hardness).
Comparative Example 1
Skis were prepared using the same soles as those
used in Example 1, and the same wax as used in Example 1 was
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applied to the soles by ironing ten times.
Test Example 1
The soles of Examples 1 to 6 and Comparative Example
1 were checked for the amount of C24Hso/ a component of the
wax, per unit volume at varying depths of the sole by the
aforementioned method using the microtome. The results are
shown in FIG. 1, wherein A to F represent Examples 1 to 6,
respectively, and G, Comparative Example 1.
The drawing shows that the higher the impregnation
temperature, the longer the impregnation time and the smaller
the hardness of the wax impregnation preventing film, the
greater is the amount of wax, and that the depth of
impregnation is not substantially dependent on the
impregnation temperature or time. It is seen that the amount
of impregnating wax and the depth of impregnation are much
smaller in the sole of Comparative Example 1 than in those of
Examples. It is also seen that the wax concentration in the
sole has such a gradient as to decrease from the surface to
the interior.
Test Example 2
Four kinds of soles having the respective average
concentrations of wax (Cz 4 Hso component) given below in the
surface portion ranging from 0 to 100 ~ m in depth were
checked for the relatlonship between the friction (slidin~)
time and the coefficient of dynamic friction (~ ) by a thrust
collar type friction tester (test conditions: sliding velocity
150 cm/sec, load 0.26 MPa, ambient temperature 25 ~C ). FIG. 2
shows the results.
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1 1
Sole S1 0.20 ~ mole/cm~
Sole S2 0.10 ~ mole/cm3
Sole S3 0.05 ~ mole/cm3
Sole S4 0.00 ~ mole/cm3
The diagram shows that scorching occurs in Sole S4
impregnated with no wax about 2 minutes later, and that Sole
S3 becomes scorched about 5 minutes later. Sole S2 is scorched
about 7 to 8 minutes later, but is usable free of trouble
since races are usually completed within 2 to 3 minutes. Sole
S1 remains free of scorching even upon lapse of 15 minutes.
Test Example 3
The skis of Examples 1 to 6 and Comparative Example
1 and skis not treated with any wax for reference were checked
for gliding properties under the following conditions.
A course was used which had a gentle slope having an
overall length of 350 m including a distance of 200 m from the
starting point to an intermediate point and a distance of 150
m from the intermediate point to the goal.
Photoelectric tubes were provided at the three
locations of the starting point, intermediate point and the
goal.
Under the conditions of 2 ~ in atmospheric
temperature, -5 ~C in snow temperature, 0 in wind force and
about 80 km/h in the speed at the goa1, the skis were used for
10 runs to measure the glide times. The result is expressed in
the range of times measured.
The skis of Examples 1 to 6 and Comparative Example
1 were ironed before use. FIG. 3 shows the results. The
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diagram reveals that the average for the 10 runs was 18.45
seconds with the skis of Example 1, 18.50 seconds with Example
2, 18 . 65 seconds with Example 3, 18 . 40 seconds with Example 4,
18 . 50 seconds with Example 5, 18 . 55 seconds with Example 6,
18.7-odd seconds with Comparative Example 1 and 18 . 95- odd
seconds with the reference. There is a difference of 0.3-odd
second between Example 4 and Comparative Example 1. This
difference corresponds to differences of 0.34 to 3.00 seconds
when calculated for downhill, giant slalom, slalom and super-
--io giant slalom races as listed in Table 1, indicating that the
skis of the invention are very superior in gliding properties.
Table 1
Alpine event Difference in Skiing Time difference
elevation (m) distance (m) (sec)
downhill 800~ 10002500~ 35002.14~ 3.00
(DH)
giant slalom
250~ 4001000~ 12000.86~ 1.03
~GSL)
slalom 140~ 220400~ 5000.34~ 0.43
(SL)
super-giant
500~ 6501500~ 20001.28~ 1.71
slalom (SGSL)
INDUSTRIAL APPLICABILITY
The skis and snowboards having a wax-impregnated
sole of the invention are entirely novel articles heretofore
unavailable. When applied by ironing, hot wax penetrates deep
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into the sole in a large quantity owing to the high affinity
thereof for the wax impregnating the sole, consequently
affording excellent gliding properties. The sole of the
invention is made of polyethylene having a high molecular
S weight and therefore has exceedingly high strength.
Further, the amount of the wax impregnating the sole
can be enhanced by selecting a low level of the hardness of
the wax impregnation preventing film.
