Note: Descriptions are shown in the official language in which they were submitted.
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PROCESS FOR IMPARTING COLOR TO MOLDED ENGINEERING
PLASTICS
BACKGROUND
[0001] This invention is generally directed to a process for imparting color
to
molded materials. In particular, the invention is directed to a process for
imparting color
to molded plastic pieces of various sports equipment. In one preferred
embodiment, the
invention is directed to imparting color to ice skate blade holders and goalie
skate
cowlings while retaining the other characteristics of the ice skate blade
holder or goalie
skate cowling, such as logos, model names, etc.
[0002] Generally, there are three major components to an ice hockey skate-the
boot, the blade and the holder. Traditionally, the boot is constructed of an
intricate
system of materials including leather, synthetics, fabrics, and plastic
inserts. The boot's
purpose is to enclose the foot and ankle, providing support and protection.
The blade is
composed of carbon steel or stainless steel and its purpose is to interface
with the ice,
allowing the skater to turn, stop, and accelerate. The ice skate holder is a
device that
permits the attachment of the steel blade to the bottom of the boot. The ice
skate holder,
normally constructed from molded plastic or polycarbonate resin thermoplastic
(Lexan ),
is affixed to the bottom of the boot with rivets or bolts and employs various
systems of
bolts or screws to secure the blade. Goalie cowlings, in addition to providing
a structure
to which to affix the steel blade, cover the lower portion of the goalie boot,
delivering
additional protection against the impacts of shots.
[0003] Generally, ice skate blade holders and goalie cowlings have been made
of
white plastic with decorations (logos, model names, etc.) applied in the form
of paint or
decals. In limited situations, holders have been molded of grey or black
plastic. Nike
Bauer in 2005 introduced a clear (translucent) Lexan holder. Many hockey
players may
prefer wider options with respect to the appearance of the ice skate blade
holders or
goalie skates that they use. For example, ice skate blade holders and goalie
cowlings
having a wide array of colors and even colored designs (e.g., player names,
numbers,
etc.) that would coordinate with a team's colors can be desirable. Most hockey
players
will choose a holder color or cowling color based on primary, secondary or
tertiary colors
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of the team uniform. The alternative driver of color selection is the presence
of the color
in another piece of equipment, especially the boot of the skate.
[0004] While non-white color variations of the skate holders and goalie
cowlings
have been produced by colorizing the raw plastic material before molding the
skate blade
holder or the cowling, a need still exists for a process for imparting color
to molded skate
blade holders and other molded plastic pieces of sporting equipment.
SUMMARY
[0005] Among the various aspects of the invention is a process for colorizing
sporting equipment comprising substantially rigid molded portions. These
substantially
rigid molded portions can be, for example, skate blade holders, goalie skate
cowlings,
lacrosse racquet heads, and hockey and lacrosse helmets.
[0006] Another aspect of the invention is a process for imparting color to a
molded article comprising submersing at least a portion of the molded article
in a dye
bath comprising an aqueous solvent and a dye wherein the molded article is
comprised of
an engineering plastic.
[0007] Other objects and features will be in part apparent and in part pointed
out
hereinafter.
DETAILED DESCRIPTION
[0008] The present invention is directed to processes for imparting color to
substantially rigid moldable, colorizable materials, particularly engineering
plastics after
they are molded into the shape of their product. Generally, the processes for
imparting
color are used for white or translucent engineering plastics. Typically, this
process for
imparting color also allows for retention of the logos, model numbers, etc.
that the
molded material contained before the process imparted color.
[0009] Generally, the process for imparting color comprises immersing a molded
article of engineering plastic in a heated dye bath for several minutes
followed by contact
with cold water.
[0010] The molded articles that are colorized by the process are typically
made
from engineering plastics. Engineering plastics are polymers having high
strength,
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stiffness, and toughness along with high thermal and oxidative stability, low
creep, and
the ability to be processed by standard techniques for thermoplastics.
Exemplary
engineering plastics are polyacetal, polyamide (nylon), polyurethane,
polycarbonate,
polysulfide, polysulfone, polyimide, polybutylene terephthalate, acrylonitrile
butadiene
styrene, polypropylene, polyvinyl chloride, polyethylene (high molecular
weight and
ultra high molecular weight), polyethylene terephthalate, polyester, and
polytetrafluoroethylene resins. In various embodiments, the molded articles
are skate
blade holders, goalie skate cowlings, lacrosse racquet heads, and hockey or
lacrosse
helmets. In various preferred embodiments, the molded articles are skate blade
holders
made of nylon or polycarbonate.
[0011] In various embodiments, the dye bath used in the process of the
invention
is prepared in a vessel that is large enough for complete submersion of the
molded article
or the portion of the molded article to be dyed. The dye bath is prepared by
placing an
aqueous solvent, particularly water (in preferred embodiments, distilled
water), in the
vessel and heating the solvent to about 90 C -100 C. Once the solvent reaches
the
desired temperature, the dye is added. Generally, the dye is added at about 1
ounce of
dye for every 4 to 6 quarts of solvent or about 28 g of dye for every 4 to 6
liters of
solvent. In various preferred embodiments, the dye is added at about 1 ounce
of dye for
every 5 quarts of solvent or about 28 g of dye for every 5 liters of solvent.
The dye and
solvent are thoroughly mixed and the temperature of the resulting dye bath is
reduced. In
various embodiments, the temperature of the dye bath is about 50 C to about
100 C,
preferably, about 60 C to about 100 C, more preferably, about 70 C to about 99
C, even
more preferably, about 90 C to about 99 C.
[0012] The dyes used in the dye bath can be those dyes known to a person
skilled
in the art. Particularly, commercial dyes including Rit dyes can be used in
the dye bath.
Solid or liquid dyes can be used, but solid dyes are preferred. Such dyes can
include
surfactants and other additives in addition to dye compounds. Custom colors
can be
prepared by following variations of the color recipes provided for Rit
ProLine dyes and
dependes on the material to be colorized.
[0013] Typically, the solvent used in the dye bath is an aqueous solvent.
Thus,
the main component of the solvent is water. Various other water miscible
solvents can be
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added to the water. However, in preferred embodiments, the solvent is water.
In some
embodiments of the process, the solvent can be distilled water.
[0014] Optionally, the dye bath can include various additives such as NaCI,
KCI,
NaHCO3, and vinegar (CH3COOH). In various preferred embodiments, vinegar is
added
in an amount which increases the color uptake of the molded article when it is
submersed
in the dye bath. The amount of vinegar used ranges from about 0.25 tablespoon
vinegar/quart water to about 0.5 tablespoon vinegar/quart water.
[0015] Generally, the first step of the process of imparting color to a molded
article is preparation of the dye bath. The dye bath is prepared and the
temperature of the
dye bath is adjusted as described above. The molded article can then be
submersed in the
dye bath. Typically, the molded article is submersed from about 6 to about 10
minutes,
preferably, from about 7 to about 8 minutes, but the time of submersion is not
narrowly
critical. In some embodiments, the molded article is submersed for about 1 to
1.5 hours.
The time for submersion depends on the temperature and concentration of the
dye bath,
the depth of color desired for the molded article, and the type of engineering
plastic.
Thus, if keeping the other variables constant, a shorter time of submersion
produces a
molded article having a less intense color.
[0016] After removing the molded article from the dye bath, the molded article
is
immediately washed with cold water to cool the molded article and remove
excess dye.
[0017] The following examples illustrate the invention.
EXAMPLE
Example 1: General Process for Imparting Color to Skate Blade Holders
[0018] A metal vessel sufficiently large to allow complete submersion of the
ibe
skate blade holder or goalie cowling was used, such as a 16 to 24 quart
cooking pot. The
vessel was filled with sufficient water to allow complete submersion of the
ice skate
blade holder or goalie cowling, normally to about 70-85% of capacity. The
water was
then brought to a slow boil at a temperature in the range of 97.8-101.1 C (208-
214 F).
Once the water reached this temperature, a commercially-available Rit brand
powdered
dye is added to the water in the amount of one (1) ounce of dye for every five
(5) quarts
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of water. In some of these experiments, vinegar was added to the solution at a
concentration of about 0.25 tablespoon vinegar/quart water to about 0.5
tablespoon
vinegar/quart water. The dry dye was then thoroughly mixed with the water to
form a
dye solution. The temperature of the dye solution was reduced to between 82.2
C
(180 F) and 93.3 C (200 F). The holder was then submersed in the dye solution
for
seven (7) to eight (8) depending on the intensity of the color desired. A
longer
submersion time resulted in greater color intensity. The holder was then
removed from
the water and immediately rinsed with cold water.
Example 2: Variations of General Process
[0019] Time of submersion. When the skate blade holder was submersed for
shorter than seven (7) minutes, generally the color produced was not as
desirable because
it was not deep or vibrant enough. When the skate blade holder was submersed
for
longer than eight (8) minutes, the quality of the color imparted was not
appreciably
affected for some dyes. For other dye colors, particularly darker dye colors,
such as blue
or black, a submersion time of 14 to 16 minutes was desirable. For some skate
holder
materials, such as translucent Lexari , the submersion time was 1 to 2 hours.
[0020] Temperature of dye bath. Generally, the process was most effective when
the temperature of the dye bath during submersion of the skate blade holder
was between
about 71.1 C (160 F) to about 98.8 C (210 F). It was found that dye bath
temperatures
higher than 93.3 C (200 F) do not impact the quality or time of coloration and
temperatures lower than 82.2 C (180 F) begin to increase the processing time
for
imparting desirable color or reduce the depth of the color imparted to the
skate blade
holder. Preferably, the temperature of the dye bath is from about about 87.8
C (190 F)
to about 93.3 C (200 F)
[0021] Type of dye. Three types of dyes were tested and Rit brand dye
produced skate blade holders having the most desirable appearance, though the
other
dyes did impart color to the skate blade holders. Rit brand liquid dye
products were
also tested, but the skate blade holders using the liquid dye did not produce
acceptable
results. In some cases, the color resulting was acceptable, but the costs for
the same
product was much greater than use of solid dyes. A number of standard Rit
brand dye
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colors and a few custom blends of dyes were tested. Skate blade holders having
a
desirable appearance were produced in the following colors: red, royal, black,
yellow,
gold, purple, pink, navy, Columbia blue, sunshine orange, and lime.
[0022] Additives to the dye bath. Small amounts of common household
chemicals such as NaCl, KCI, vinegar (CH3COOH), and NaHCO3 were also added to
the
dye bath for some experiments. Although NaCI, KCI, and NaHCO3 did not produce
a
considerable difference in the results of the process, in some cases they did
produce very
slight differences in the depth of color and shades of color imparted to the
skate blade
holders. Therefore, these additives can be used to achieve a desired color
depth or shade.
When vinegar was added the color uptake to the skate holder was enhanced. A
small
amount (e.g., 0.25 tablespoon vinegar/quart water to about 0.5 tablespoon
vinegar/quart
water) was used for this purpose.
[0023] Deionized water. Use of deionized (or distilled) water as the solvent
in the
dye bath produced skate blade holders with slightly shinier finishes. However,
the added
cost of this solvent outweighed the incrementally improved appearance of the
skate blade
holder.
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