U.S. patent application number 10/631458 was filed with the patent office on 2004-02-12 for solvent-activated color forming compositions.
Invention is credited to Elhard, Joel D., Heggs, Richard P..
Application Number | 20040029289 10/631458 |
Document ID | / |
Family ID | 24226670 |
Filed Date | 2004-02-12 |
United States Patent
Application |
20040029289 |
Kind Code |
A1 |
Elhard, Joel D. ; et
al. |
February 12, 2004 |
Solvent-activated color forming compositions
Abstract
Color-forming compositions comprising (i) a solvent absorbing
material such as a polymer; (ii) a color-former or chelating agent
compounded with the solvent absorbing material; and (iii) a source
of metal ions, whereby the metal ions complex with the color former
as the solvent absorbing material absorbs the solvent, resulting in
a detectable color change of the solvent absorbing material. Both
reversible and irreversible versions of these color-forming
compositions are provided.
Inventors: |
Elhard, Joel D.; (Hilliard,
OH) ; Heggs, Richard P.; (Dublin, OH) |
Correspondence
Address: |
BATTELLE MEMORIAL INSTITUTE
505 KING AVENUE
COLUMBUS
OH
43201-2693
US
|
Family ID: |
24226670 |
Appl. No.: |
10/631458 |
Filed: |
July 30, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10631458 |
Jul 30, 2003 |
|
|
|
09557733 |
Apr 26, 2000 |
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Current U.S.
Class: |
436/166 |
Current CPC
Class: |
A63B 37/0024 20130101;
A63B 37/12 20130101; A63B 43/008 20130101; G01N 31/222 20130101;
C08K 5/13 20130101; A63B 37/0003 20130101 |
Class at
Publication: |
436/166 |
International
Class: |
G01N 021/75 |
Claims
1. A solvent-activated, color-forming composition, comprising: (a)
a solvent-absorbing material; (b) a color former compounded with
said solvent-absorbing material, wherein said color former is a
chelating agent; and (c) a source of metal ions capable of
complexing with said color former as said solvent-absorbing
material absorbs said solvent, resulting in a detectable color
change of said solvent-absorbing material.
2. The color-forming composition of claim 1, wherein said solvent
is polyethylene acrylic acid ionomer containing about 5% titanium
dioxide filler resin; said color former is about 0.15% to 2.0%
1,2-Dihydroxybenzene; and said source of metal ions is about 0.25%
to 2.0% zinc acetate.
3. A color-forming composition, comprising: (a) a solvent; (b) a
solvent-absorbing material; (c) a color former compounded with said
solvent-absorbing material, wherein said color former is a
chelating agent; and (d) a source of metal ions capable of
complexing with said color former as said solvent-absorbing
material absorbs said solvent, resulting in a detectable color
change of said solvent absorbing material.
4. The color-forming composition of claim 3, wherein said
color-forming composition exhibits thermoxidative stability at
compounding temperatures of at least 104.degree. C.
5. The color-forming composition of claim 3, wherein said
color-forming composition exhibits thermoxidative stability at
extrusion temperatures of at least 207.degree. C.
6. The color-forming composition of claim 3, wherein said solvent
is water.
7. The color-forming composition of claim 3, wherein in said
solvent is an inorganic solvent.
8. The color-forming composition of claim 3, wherein in said
solvent is an organic solvent.
9. The color-forming composition of claim 3, wherein said solvent
absorbing material is a polymer or a polymer composite.
10. The color-forming composition of claim 9, wherein said polymer
is polyethylene acrylic acid ionomer containing about 5% titanium
dioxide filler resin.
11. The color-forming composition of claim 3, wherein said solvent
absorbing material is paint.
12. The color-forming composition of claim 3, wherein said solvent
absorbing material is a synthetic construction material selected
from the group consisting of polyvinyl chloride, polyurethane,
silicone elastomers, and organic rubbers.
13. The color-forming composition of claim 3, wherein said color
former is 1,2-Dihydroxybenzene.
14. The color-forming composition of claim 13, wherein said color
change is not reversed by the removal of said solvent from said
solvent-absorbing material.
15. The color-forming composition of claim 3, wherein said color
former is an aromatic di-hydroxy compound.
16. The color-forming composition of claim 15, wherein said color
change is not reversed by the removal of said solvent from said
solvent-absorbing material.
17. The color-forming composition of claim 15, wherein said
aromatic dihydroxy compound is selected from the group consisting
of 3-Methylcatechol, 4-Methylcatechol, 4,5-Dihydroxy
1,3-benzenedisulfonic acid disodium salt and
1,2,3-Trihydroxybenzene.
18. The color-forming composition of claim 17, wherein said color
change is not reversed by the removal of said solvent from said
solvent-absorbing material.
19. The color-forming composition of claim 3, wherein said
chelating agent is a diethylaminofluroan based dye or a
diethylamino analog.
20. The color-forming composition of claim 19, wherein said color
change is reversed by the removal of said solvent from said
solvent-absorbing material.
21. The color-forming composition of claim 3, wherein said source
of metal ions is said solvent.
22. The color-forming composition of claim 3, wherein said source
of metal ions is said solvent-absorbing material.
23. The color-forming composition of claim 3, wherein said source
of metal ions is a metal salt.
24. The color-forming composition of claim 3, wherein said metal
ions are zinc ions.
25. The color-forming composition of claim 3, wherein said metal
ions are iron, sodium, calcium, magnesium, lithium, titanium, or
magnesium ions.
26. A method of making a color-forming composition, comprising the
steps of: (a) providing a solvent-absorbing material, a chelating
agent, and a source of metal ions; (b) dry blending said
solvent-absorbing material, said chelating agent, and said metal
ions in a batch process; and (c) compounding said batch in an
extruder or other suitable mixing device.
27. A method of making a color-forming composition, comprising the
steps of: (a) providing a solvent-absorbing material, a chelating
agent, and a source of metal ions; and (b) metering said
solvent-absorbing material, said chelating agent, and said metal
ions into an extruder or other continuously compounding device.
28. A method of making a color-forming composition, comprising the
steps of: (a) providing a solvent-absorbing material, a chelating
agent, and a source of metal ions; and (b) dry blending or
continuously metering said solvent-absorbing material, said
chelating agent, and said source of metal ions into the final
processing step, wherein said final processing step has a minimum
amount of mixing capability.
29. A method of making a color-forming composition, comprising the
steps of: (a) providing a solvent-absorbing material, a chelating
agent, and a source of metal ions; and (b) at the final fabrication
step, adding said chelating agent and said source of metal ions to
said solvent absorbing material at a level higher than that
required for the desired final concentration of said chelating
agent and said source of metal ions in said solvent-absorbing
material.
30. A method for indicating exposure of a material to a solvent,
comprising: (a) providing a solvent; (b) providing a
solvent-absorbing material; (c) compounding a color-former with
said solvent-absorbing material, wherein said color-former is a
chelating agent; (d) providing a source of metal ions; and (e)
contacting said solvent-absorbing material with said solvent,
whereby as said solvent is absorbed by said solvent-absorbing
material, said metal ions contact and complex with said
color-former resulting in a detectable color change of said
solvent-absorbing material.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to solvent-activated and
solvent-sensitive color forming compositions, their method of
making and method of use.
[0002] Prolonged exposure to, or immersion in, certain solvents
(e.g., water) can adversely affect the physical, chemical and
mechanical properties of some polymer materials, composite
materials, and synthetic construction materials. For example, the
exterior of golf balls typically consists of one or more polymer
materials. A golf ball that has been submerged in a water hazard
for an extended period of time will exhibit inferior flight
characteristics compared to a new golf ball, despite the
superficial similarity in appearance of the two golf balls (Golf
Digest, Sept 1996). In some instances, the diminished performance
of certain materials caused by prolonged exposure to a solvent is
temporary and mostly reversible if the solvent is removed by drying
the affected materials. In other situations the effects are
permanent and performance is irreversibly damaged. In certain
situations, any exposure to a solvent, however brief, may create
performance concerns. Thus, there is a need for a color-based
indicator that can be incorporated into various solvent-sensitive
materials which will alert the user to the possibility that the
performance of the materials has been compromised by exposure to,
or immersion in, a given solvent. Ideally, color formation would be
either reversible or permanent based on different formulations of
the indicator and the material it is combined with.
[0003] Several water-sensitive color systems currently exist. U.S.
Pat. No. 5,130,290 to Tanimoto discloses a water-sensitive coloring
sheet which includes a substrate and a water-sensitive coloring
layer containing an unencapsulated color developing material that
reacts with a dye when the coloring layer is wetted. The inclusion
of a desensitizing material in this system results in a reversible
color formation system (i.e., the removal of water results in the
removal of the color). U.S. Pat. No. 5,501,945 to Kanakkanatt
discloses the concept of a reversible system in which water
sensitive chemichromic dyes are incorporated into polymers used for
various packaging applications. U.S. Pat. Nos. 5,823,891 and
5,938,544, both to Winskowicz disclose a color-forming system for
use with golf balls which utilizes a water permeable covering over
the core of a golf ball, and a water soluble pelletized or
microencapsulated colored dye near or within the covering.
[0004] All of the discussed systems require some type of colored
dye which when subjected to the correct stimulus undergoes a color
change. Such dyes must often be processed, i.e., pelletized or
microencapsulted, before they can be incorporated into a particular
material. Processing dyes in the manner adds difficulty and expense
to the process of creating a water-activated color forming
material. Furthermore, these dyes may be removed by simply
bleaching the colored material.
BRIEF SUMMARY OF THE INVENTION
[0005] These, and other deficiencies of the prior art are overcome
by the present invention which provides a color-forming composition
that includes a solvent absorbing material such as a polymer, a
chelating agent or "color former" that is compounded with the
solvent absorbing material, and source of metal ions such as zinc
acetate. The metal ions form a chelate complex with the color
former as a solvent (e.g., water) is absorbed by the polymer
resulting in the polymer changing color. The color-forming
composition of the present invention is white or colorless after
initial processing and does not change color until it has absorbed
the solvent. This color-forming composition is essentially
"aquachromic" meaning that color change occurs upon exposure to
liquid water, but is not "hydrochromic" because exposure to
moderate humidity alone does not initiate a color change. Once the
color change has occurred, the color-forming composition of this
invention is unaffected by treatment with typical solutions
designed for color removal for extended periods of time.
[0006] Therefore, it is an object of the present invention to
provide a color-forming composition that can be used for multiple
purposes, including use as the outer cover of golf balls, whereby
prolonged exposure of the color-forming composition to a liquid
solvent, such as water, results in a detectable color change of the
composition.
[0007] It is an additional object of the present invention to
provide both a reversible and an irreversible color forming
composition, whereby the color change is permanent upon the removal
of a solvent from the composition, or whereby the color change is
temporary, and the color fades from the composition upon removal of
the solvent from the composition, but can be regenerated upon
repeated exposure to the solvent.
[0008] Further objects, advantages, and novel aspects of this
invention will become apparent from a consideration of the figures
and subsequent detailed description.
BRIEF DESCRIPTION OF THE FIGURES
[0009] FIG. 1 depicts a color formation vs. time plot for the
irreversible color forming embodiment of the present invention. In
a typical experimental procedure, samples of each composition are
compounded on a 2-roll mill at about 104.degree. C. (220.degree.
F.), compression molded into a plaque form, cut to about 2.times.5
inches size, weighed on an analytical scale, and the initial color
measured using a X-rite (L,a,b values). The samples are then
immersed in water. Periodically, samples are removed, reweighed,
and the color remeasured.
[0010] FIG. 2a depicts a color formation vs. time plot for the
reversible color forming embodiment of the present invention before
an extrusion check for thermo-oxidative stability. See the legend
for FIG. 1 for a description of analytical test procedures.
[0011] FIG. 2b depicts a color formation vs. time plot for the
reversible color-forming embodiment of the present invention after
an extrusion check for thermo-oxidative stability. See the legend
for FIG. 1 for a description of analytical test procedures.
DETAILED DESCRIPTION OF THE INVENTION
[0012] In general, the present invention provides a color-forming
composition that includes a solvent-absorbing material, a chelating
agent or "color former" that is compounded with the solvent
absorbing material, and a source of metal ions. The metal ions form
a chelate complex with the chelating agent or color former as a
solvent (e.g. water) is absorbed by the solvent-absorbing material,
resulting in a color change of the solvent absorbing material. For
example, the solvent-absorbing material may change from white to
green, brown, or black. The color-forming composition of the
present invention is white or colorless after initial processing,
and does not change color until it has absorbed water. Furthermore,
the present invention provides a color-forming composition that is
essentially "aquachromic" meaning that color change occurs upon
exposure to liquid water (or other solvent), but that is not
"hydrochromic" because exposure to moderate humidity alone does not
initiate a color change. Finally, once the color change has
occurred, the color-forming compositions of this invention are
unaffected by treatment with typical solutions designed for color
removal (e.g., 3% H.sub.2O.sub.2, 1M HCl, Alconox, Clorox Bleach)
for extended periods of time. Long term exposure to hazardous
solvents such as bleach will ultimately degrade the polymer itself,
thus the polymer will break down before the color change can be
removed.
[0013] In a preferred embodiment of the present invention, the
color-forming composition is used as the outer cover for golf
balls, which is typically white. The solvent absorbing material is
the polymer polyethylene acrylic acid ionomer containing about 5%
titanium dioxide filler (tradename SURLYN), the color former or
chelating agent is 1,2-Dihydroxybenzene (also known as Catechol),
and the metal ions are zinc (+2) from zinc acetate. In the
preferred embodiment, the polymer, the color changer, and the Zn
(+2) ions are compounded to form the outer cover of the golf ball.
In another embodiment, only Catechol is compounded with the polymer
and color former, and the source of metal ions is derived from the
ionomer itself, the solvent, or from another source. The preferred
solvent is water, and if a golf ball covered with the color-forming
composition of the present invention is submersed in water for an
extended period of time (e.g. about two to eight days), the polymer
absorbs water, thereby moving the Zn (+2) ions (individually or
complexed with another material) into contact with the color
former, or vice-versa. The metal ions and the color former form a
chelate complex which results in a permanent darkening of the outer
cover of the golf ball. FIG. 1 provides a representative color
formation vs. time plot for the preferred embodiment. In this
embodiment, the darkened color cannot be reversed if the water is
removed from the outer cover. The performance of the color
formation in a particular polymer system can be controlled by the
type and loading of both the color former and the corresponding
metal ion, where performance includes rate of color formation,
final color level achieved, stability (shelf-life) under elevated
temperature and humidity conditions, as desired. A preferred
formulation for this embodiment includes: polyethylene acrylic acid
ionomer or ionomer blend (e.g., 80% Surlyn 8940, 20% Surlyn 9910)
containing about 5% titanium dioxide filler resin; and from about
0.15% to 2.0% 1,2-Dihydroxybenzene, and from about 0.25% to 2.0%
Zinc acetate. The optimum color formation in these systems is
achieved with a stoichiometric ratio of chelating agent and metal
ion (e.g. about 1.67:1 Zn Acetate/ Catechol or integer multiples
thereof).
[0014] Adding greater amounts of color forming components (i.e.,
chelating agent and metal ions) results in increased rapidity and
intensity of color formation. Substitution of certain components
will also increase rapidity and intensity of color formation; for
example, in one embodiment Mg (II) acetate is used place of Zn (II)
acetate to create a more rapid color change. In other embodiments
of the present invention, certain adjuvants are added to the
composition to enhance or inhibit the water absorption of the base
polymer and modify the color formation process. These additives
include, but are not limited to, pentaerythritol, ethylene glycol,
polyethylene glycol, and polyacrylic acid.
[0015] A preferred embodiment of the present invention exhibits
thermooxidative stability at compounding temperatures of at least
104.degree. C. (220.degree. F.) and extrusion temperatures of at
least 207.degree. C. (450.degree. F.). This embodiment also
exhibits stability against premature color formation under elevated
temperature and humidity conditions. For example, representative
formulations exposed to 40-45.degree. C. (104-113.degree. F.) and
75% RH (relative humidity) in an environmental chamber for a period
of 24 hours show no discemable color change (less than about 1 L
unit). Similarly, materials exposed to milder, ambient-like
conditions (e.g., about 72OF/ 45% RH) show no discernable change
for at least a week, compared to the substantial color development
(40-50 L units) over the same period of water immersion.
[0016] For purposes of example, Catechol complexed with Fe(+3) has
the following expected structure: 1
[0017] Alternatively, the chelate-complex may be present in a form
where the additional ligands (e.g. acetate and hydrate forms) also
participate, as shown for the Zinc (II) diacetate
dihydrate-catechol complex below: 2
[0018] In an alternate embodiment this invention, the preferred
source of metal ions is zinc acetate, and the color former is a
diethylaminofluroan-based dye (tradename PERGASCRIPT BLACK I-R).
Use of this dye results in the reversible formation of color in the
outer cover of the golf ball when absorbed water is removed from
the outer cover by drying. In this embodiment, reversibility of the
color change is maintained as long as the level of Zn (+2) ionomer
in the total composition does not exceed about 50%. A typical
preferred formulation for this embodiment includes: about 2 pph
polyethylene acrylic acid ionomer containing about 5% titanium
dioxide filler resin; about 1 pph diethylaminofluroan based dye
resin; and about 2 pph zinc acetate (anhydrous<0.2 wt % water)
resin. This embodiment also exhibits thermooxidative stability at
compounding temperatures of at least 104.degree. C. (220.degree.
F.) and extrusion temperatures of at least 207.degree. C.
(450.degree. F.). FIG. 2a and FIG. 2b provide color formation
versus time plots for the reversible embodiment of the present
invention before and after an extrusion check for thermo-oxidative
stability. Structures for PERGASCRIPT BLACK I-R (PB-IR) as
determined by nuclear magnetic resonance (NMR), and a likely
complex with Zn acetate during water immersion are shown below:
3
[0019] In other embodiments of the present invention, the polymer
polyethylene acrylic acid is replaced with other polymers including
polyurethane, poly-(acrylonitrile-butadiene-styrene), polyvinyl
chloride, polypropylene-copolymer, and polystyrene or combinations
thereof. These polymers are widely used in a number of industrial
and packaging applications. In alternate embodiments, the solvent
absorbing material is paint, or synthetic construction material
such as polyvinyl chloride, polyurethane, silicone elastomers, or
organic rubbers.
[0020] In other embodiments of the present invention, the solvent
is an inorganic solvent such as ammonium hydroxide, hydrogen
peroxide, hydrochloric acid, or hypochlorite (bleach); or an
organic solvent such as ethanol, ethyl acetate, toluene, xylene, or
diesel fuel. Preferred organic solvents are those exhibiting some
degree of polarity such as ethyl acetate and tetrahydorfuran.
[0021] In alternate embodiments where color formation is
irreversible, the color former is selected from aromatic di-hydroxy
compounds such as 3-Methylcatechol, 4-Methylcatechol, and
4,5-Dihydroxy 1,3-benzenedisulfonic acid disodium salt (Tiron), or
alternatively, 1,2,3-Trihydroxybenzene (pyrogallol). In an
alternative embodiment where color formation is reversible, the
color former is the dimethylamino analog PERGASCRIPT BLACK
I-2R.
[0022] The source of metal ions may vary widely in alternative
embodiments. For example, in one embodiment, the source of metal
ions is the solvent itself. In another embodiment, the source of
metal ions is the solvent-absorbing material. In still another
embodiment the source of the metal ions is any one of a variety of
metal salts. In alternative embodiments, the metal ions themselves
are Zn (+2), Fe (+3), Na (+), Ca (+2), Mg (+2), Li (+), Ti (+2), Mn
(+2), or any other suitable metal ion, both as isolated cations and
with other coordinating ligands such as hydrate, acetate, or ester
forms (e.g., Zn(II) 3,5-di-t-butylsalicylate).
[0023] One method of making a color-forming composition of the
present invention includes the steps of: (i) providing a
solvent-absorbing material, a chelating agent, and a source of
metal ions; (ii) dry blending the solvent-absorbing material, the
chelating agent, and the metal ions in a batch process; and (iii)
compounding the batch in an extruder or other suitable mixing
device. An alternative method of making a color-forming
composition, includes the steps of (a) providing a
solvent-absorbing material, a chelating agent, and a source of
metal ions; and (ii) metering the solvent-absorbing material, the
chelating agent, and the metal ions into an extruder or other
continuously compounding device. Another method of making a
color-forming composition includes dry blending or continuously
metering the active ingredients into the final processing step,
provided that the final processing step has a minimum amount of
mixing capability such as provided by an injection molder or an
extruder.
[0024] A preferred method for making a color-forming composition,
which utilizes a "masterbatch" includes the steps of: (i) providing
a solvent-absorbing material, a chelating agent, and a source of
metal ions; and (ii) at the final fabrication step, adding the
chelating agent and the source of metal ions to the solvent
absorbing material at a level higher than that required for the
desired final concentration of the chelating agent and the source
of metal ions in the solvent-absorbing material. For example, a
pigment masterbatch may contain 40% pigment by weight, while the
final product may only contain 4% or less. In this embodiment, the
masterbatch is mixed with the base resin at the final fabrication
step such as injection molding in a ratio that results in the final
desired additive amount.
[0025] The benefits of the masterbatch approach include the
following: (i) additives can be handled in the "neat" or 100%
concentrated state at a remote location for safety or other reasons
such as the need for special handling equipment (as in the case of
liquid additives) or the desire to minimize the risk of
contamination of other products; (ii) the masterbatches improve
dispersion of the additive in the final product by being processed
twice (many final fabrication processes typically optimize the
plastication or melting of the polymer rather than optimize
mixing); (iii) additives are sensitive to environmental degradation
such as moisture or light the small volume of masterbatch can be
more easily protected and handled; (iv) a resin of different
characteristics can be used for the masterbatch and the final
product to improve processing. For example, the masterbatch resin
could be lower in viscosity to increase the amount of additive it
can contain while the resin for the final part may be higher in
viscosity to improve mechanical properties; and (v) masterbatches
can use very aggressive and expensive mixing equipment such as twin
screw extruders while the final product can use equipment suited to
the formation of the part.
[0026] While the above description contains many specificities,
these should not be construed as limitations on the scope of the
invention, but rather as exemplification of preferred embodiments.
Numerous other variations of the present invention are possible,
and it is not intended herein to mention all of the possible
equivalent forms or ramifications of this invention. Various
changes may be made to the present invention without departing from
the scope of this invention.
* * * * *