Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVED EFFECT PIGMENT
BACKGROUND OF THE INVENTION
The use of effect pigments, also known as pearlescent pigments or
nacreous pigments, in order to impart a pearlescent luster, metallic luster
and/or multi-color effect approaching iridescent, is well-known.
The effect pigments are composed of a plurality of laminar platelets,
each of which is coated with one or more reflecting/transmitting layers.
Pigments of this type were first based on metal oxides, as described in
U. S. 3,087, 828 and 3,087, 829, and a description of their properties can be
found in the Pigment Handbook, Volume I, Second Edition, pp. 829- 858,
John Wiley & Sons, NY 1988. More recently, use of other coating layers to
realize optically variable effects have been developed.
The unique appearance of effect pigments is the result of multiple
reflections and transmissions of light. The platelet substrate usually has a
refractive index which is different from the coating and usually also has a
degree of transparency. The coating is in the form of one or more thin films
which have been deposited on the surfaces of the platelets.
There are a number of important aspects to effect pigments. One is
that they are commonly composed of a plurality of particles which are platelet
shaped. If there is a different size or shape, the pearlescent or nacreous
appearance is significantly diminished and usually lost to a degree that the
material no longer functions as an effect pigment.
One important aspect of the coating on the platelet is that it must be
smooth and uniform in order to achieve the optimum pearlescent appearance.
The reason is that if an irregular surface is formed, light
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scattering occurs and the coated platelet will no longer function as an
effect pigment.
In addition, the coating should adhere strongly to the platelet or
else the coating will become separated during processing, resulting in
considerable breakage and loss of luster. Particles which do not become
attached to the platelet during preparation of the coatings on the
platelets or which are the result of separation cause light scattering and
impart opacity to the pigment. When there are too many of such small
particles, the pearlescent appearance can be reduced or lost.
The addition of the coatings to a platelet so that the luster, color
and color homogeneity are maintained is a very complex process and
originally, the only platy substrate which achieved any significant use in
commerce was mica. Thus, historically, the largest class of effect
pigments based on thin film interference were those based on a mica
substrate. With the advent of synthetic substrates, e.g. synthetic mica,
aluminum oxide, silica, and glass, it became evident that other
substrates could be used since each substrate itself contributes certain
effect attributes, due to variations in transparency, refractive index,
bulk color, thickness, and surface and edge features. Coated substrate
effect pigments thus provide different, albeit similar, visual effects when
they are identical except for the identity of the material of the platelet
because of these considerations.
Glass flakes are desirable in the industry because they are very
resilient and can be optically attractive as well. In one method, glass
flakes are made by stretching a molten glass into thin sheets, beads or
glass tubes followed by crushing the glass into flakes. The resulting
flakes have a size and shape mimicking the mica platelets used in metal
oxide-coated mica pearlescent pigments and thus have an average
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particle size in the range of about 1 to 150 microns and a thickness of about
0.1 to 10 microns.
A commercially viable method of preparing metal oxide-coated glass
platelets is described in U.S. 5,753, 371. That patent discloses the coating
of
C glass in preference to A or E glasses. A glass is a soda-lime glass,
commonly used to make windows and contains more sodium than potassium
and also contains calcium oxide. C glass, also known as chemical glass, is a
form which is resistant to corrosion by acid and moisture. E or electrical
glass
is, as the name implies, designed for electronic applications and although it
is
very stable at high temperatures, it can be susceptible to chemical attack.
See
also commonly assigned U. S. patent 6,045,914.
International Publication WO 03/006558 A2 and WO 02/090448 A2
disclose a pigment based on glass flakes wherein the glass flakes have a
softening point of >_ 800 C ; a preferred glass is quartz. ENGELHARD
REFLECKSTM Pearlescent and Iridescent Pigments brochure dated 2000
teaches a borosilicate pigment with TiO2. See also Japanese Patent
Publication 11340 published January 16, 2001 teaching a glass flake
pearlescent pigment.
Metal oxide-coated mica effect pigment and a metal oxide-coated glass
effect pigment do provide different visual effects even if they are identical
except for the material of the platelet substrate. The reason is that the mica
and the glass differ with respect to both their degree of transparency,
refractive index, and bulk color. Also, while the surfaces of both are
sufficiently smooth for effect pigment use, the glass surface is the smoother
of
the two substrates and that provides a different optical appearance. Platy
aluminum oxide has a surface of similar
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smoothness to glass. Effect pigments derive their appearance by the
reflection and transmission of light and the difference in transparency
and refractive index causes the amount of light reflected or transmitted
to differ. Nevertheless, both types of effect pigments are highly
attractive and commercially valuable.
The preparation of coated glass platelets, while highly desirable, is
also expensive. For commercial acceptability, C glass is generally
required and this type of glass is costly. In addition, the calcining
temperatures employed must be maintained low since the coated glass
platelets tend to fuse starting around 650 C and any significant amount
of fusion, generally starting at about 1% by weight of the glass platelets
results in the formation of large masses which do not provide the
desired pearlescent effect because of their size and irregular shape.
Separating the fused platelets from the separate platelets is both time
consuming, costly and impractical. In addition, the required lower
calcining temperature means that the temperature must be maintained
for a longer period of time, which also adds to the cost.
Efforts have been made to find a way to reduce the cost of
producing the coated glass effect pigment. Theoretically, this could be
accomplished by blending coated glass pigment with coated mica
pigment. However, this approach has not proven to be effective
because the difference in transparency and refractive index between the
two platelet materials, in addition to process variations, makes it
extremely difficult to match the two blended materials with -respect to
apparent color. As a practical matter, therefore, it has not been
possible to provide a degree of visual homogeneity with a blend which
approaches the visual homogeneity of each member of the blend when
considered in isolation. This result is not surprising in light of the
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knowledge in the art. When two or more effect pigments using different
substrates are combined together, the attributes of each are present,
which results in a unique appearance. One problem with combining
effect pigments is that, since the color effects are generated by an
additive mechanism instead of a subtractive mechanism, small
variations in the color of two effect pigments can result in various
degrees of washed out appearance of their blend. This defeats the
basic appearance value of the pigment. It can, however, be useful to
achieve some other attribute as, for example, to simultaneously achieve
an acceptable degree of hiding power and gloss as described in U.S.
6,267,810.
U.S. 5,277,711 describes a mixture of iron oxide-coated
aluminum flake and iron , oxide-coated mica with or without a prior
coating of a colorless, highly refractive metal oxide. The purpose of the
i5 mica is to reduce the ignition in air and dust explosion hazard
otherwise exhibited by the aluminum flake. The mixture is made by
conjointly coating the aluminum and mica particles with iron oxide in a
fluidized bed by gas phase decomposition of iron carbonyl. The
appearance of the mixture, homogeneous or otherwise, was not a
consideration.
It has now surprisingly been discovered that a visually
homogeneous blend of coated effect pigments in which the substrate
platelets are of different platy materials can be achieved despite
differences in thickness, refractive index and transparency of the
platelet materials. It was also surprisingly discovered that with respect
to glass platelets premixed with mica, a visually homogeneous product
could be made by a process in which the calcining temperature was
higher than that employed with coated glass only platelets, thereby
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reducing the time needed to complete the calcining and further reducing
the cost of producing the product.
SUMMARY OF THE INVENTION
This invention relates to an effect pigment comprising a coated
mixture of at least two different materials wherein the effect pigment
exhibits visual homogeneity. Each of the at least two different materials
is present from at least about 5 weight percent to about 95 weight
percent based on the total of the at least two different materials. This
minimum of about 5 weight percent differentiates over prior art
products wherein an impure substrate was used and such impure
substrate may be considered a mixture. The present invention
intentionally adds the second different material in order to achieve the
unexpected results discussed below.
In another example, the present invention relates to an effect
pigment which is a mixture of coated platelets of different materials
which is visually homogeneous and to the method to produce the effect
pigment. More particularly, the effect pigment is a mixture of coated
laminar platelets, preferably metal oxide-coated laminar platelets, in
which the platelets are a mixture of different materials, e.g., glass and
mica, and in which the effect pigment exhibits visual homogeneity which
is produced by blending the different platelets before they are coated.
The same degree of color homogeneity and appearance is not obtained
from a combination of separately coated substrates that are blended
after the substrates are coated.
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DESCRIPTION OF THE INVENTION
The phrase "coated mixture of at least two different materials" as
used herein means that the at least two different materials are first
mixed together and then the mixture is coated.
An effect pigment is formed in accordance with the present
invention by any process known in the art. It can be accomplished, as
one example, by precipitating the metal ion onto laminar platelets and
thereafter calcining the coated platelets to provide metal oxide-coated
platelets. The metal oxide in most widespread use is titanium dioxide,
followed by iron oxide. Other usable oxides include (but are not limited
to) tin, chromium and zirconium oxides as well as mixtures and
combinations of oxides. For convenience, the description of this process
which follows will be primarily concerned with titanium and iron as the
metal of the oxide but it will be understood that any other known metal
or combination of metals can be used.
Other useful combinations of metal oxides include Si02 on
calcium aluminum borosilicate and then Ti02 thereon; substrate/SiO-
2/Fe2O3; substrate/Ti02/SiO2i substrate/Ti02/SiO2/Ti02i
substrate/Ti02/Si02/Fe203: substrate/TiO2/SiO2/Cr2O3i
substrate/Fe203/Si02i substrate/Fe203/SiO2/Fe2O3;
substrate/Fe203/Si02/Ti02i substrate/Fe203/SiO2/Cr203i
substrate/Cr203/SiO2/Cr203; and substrate/Cr203/SiO2/Fe2O3. Other
combinations of the above mentioned layers are obvious to one
skilled in the art.
An interlayer to enhance performance attributes may also be
used. Useful interlayer materials include the hydroxides and oxides of
Al, Ce, Cr, Fe, Mg, Si, Ti, and Zr. Essentially any organic or inorganic
substance may be a useful interlayer for adhesion promotion,
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mechanical integrity, product enhancement, or other desirable
attributes.
In general, the procedure involves dispersing the particulate
(flakes) and combining that dispersion with a precursor which results in
the formation of a titanium oxide or iron oxide precursor coating on the.
flakes. Usually, the particulate or flakes are dispersed in water, which is
preferably distilled. The average particle size of the flakes preferably
used can vary from an average of about 3 microns to an average of
about 100 microns, although smaller flakes of down to about 1 micron
or less or larger flakes of up to 150 microns or more can also be used if
desired. The platelets have a thickness of about 0.1 to 10 pm and an
aspect ratio (average particle size/thickness) of at least about 10. The
concentration of the particulate in the water can vary from about 5 to
60%, although the generally preferred concentrations vary between
is about 10 and 20%.
To the water/particulate slurry is added an appropriate metal ion
source material. In the case of titanium, titanyl chloride or titanium
tetrachloride is preferably used and in the case of iron, the source
material is preferably ferric chloride. The pH of the resulting slurry is
maintained at an appropriate level during the addition of the titanium or
iron salt by the use of a suitable base such as sodium hydroxide in order
to cause precipitation of a titanium dioxide or iron oxide precursor on
the particulate. Increasing the thickness gives rise to interference
colors. If desired, layers of titanium and iron hydroxide and/or oxide
(or other metals) can be deposited sequentially. If necessary to lower
the pH, an aqueous acid such as hydrochloric acid can be used. The
coated platelets can, if desired, be washed and dried before being
calcined to the final effect pigment.
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When titanium dioxide-coated products are prepared, both anatase and
rutile crystal modifications are possible. The highest quality and most stable
pearlescent pigments are obtained when the titanium dioxide is in the rutile
form. Some substrates, including both mica and glass, are anatase directing,
and it is therefore necessary to modify the foregoing procedure if a rutile
product is desired. The modifications necessary to realize a rutile TiO2 are
known in the art. One procedure involves the precipitation of a tin hydroxide
or
oxide entity on the surface of the particulate before the formation of the
layer
of titanium dioxide precursor. The layered combination is processed and
calcined. This procedure is described in detail in U. S. Patent 4,038,099. An
alternative procedure is described in U. S. 5,433, 779 and involves deposition
of the titanium dioxide precursor on the substrate in the presence of iron and
calcium, magnesium and/or zinc salts without the use of tin. While rutile
coatings are preferred, it can be desirable to produce anatase coatings and
this is also within the scope of the present invention.
Other coating procedures, such as for example, chemical vapor
deposition processes, can also be used.
Optically variable effect pigments have been developed more recently.
These are constructed with the substrate being coated with a reflecting layer
(e. g., silver, gold, platinum, palladium, rhodium, ruthenium, osmium, iridium
or their alloys) which is overcoated with a low index of refraction material,
typically having a refractive index from 1. 3 to 2.5, that provides a variable
path length for light dependent on the angle of incidence of light impinging
thereon (for instance, MgF2 or SiO2), which in turn may be overcoated with a
third layer selectively
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transparent to light directed thereon (e.g., silicon, iron oxide, chromium
oxide, a mixed metal oxide, titanium dioxide, titanium nitride and
aluminum, as well as the same materials as the first layer provided they
are sufficiently thin as to be selectively transparent). Examples of such
pigments and the processes by which they can be produced can be
found, inter alia, in U.S. patents 5,135,812, 4,434,010 (teaching for
example alternating layers of Ti02 and Si02), 5,059,245, 5,281,480,
5,958,125, 6,160,208, 6,325,847 and 6,440,208.
The different materials or substrates used in the present invention
may have any morphology including platelet, spherical, cubical, acicular,
whiskers, or fibrous. Examples of useful platy materials include platy
aluminum oxide, platy glass, aluminum, mica, bismuth oxychloride,
platy iron oxide, platy graphite, platy silica, bronze, stainless steel,
is natural pearl, boron nitride, silicon dioxide, copper flake, copper alloy
flake, zinc flake, zinc alloy flake, zinc oxide, enamel, china clay, and
porcelain and the like. Any combination of the preceding platy materials
or at least one of the preceding platy materials and at least one non-
platy material may be used. For convenience, the following description
will focus on the combination of glass and mica, although other
combinations can be used. Mica is desirable because of its high
transparency, strong reflectance and strong chroma, primarily due to
the presence of small, coated flakes. Glass flakes have the attributes of
high transparency, very white bulk color and a sparkle effect in strong
light but, as noted above, its high cost and melting point preclude its
use in many applications.
Examples of useful spherical materials include glass, plastic,
ceramic, metal, or an alloy and the spheres may be solid or hollow.
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Useful glass spheres are disclosed in US Patent 5,217,928.
Useful cubical material includes glass cubes.
In one example, the present invention uses a blend of two or
s more laminar substrates. Preferably, one of the substrates is either
platy aluminum oxide or platy glass.
Individually, each substrate can constitute about 5 to 90% of the
mixture although it is preferred that the majority of the blend is
constituted by one substrate, e.g., mica. More preferably, the blend
to contains at least about 65% mica and even more preferably at least
about 75% mica. Individually, the mica platelets and glass platelets
have an average particle size and thickness in the ranges specified
above. The particle dimensions are selected so that the resulting
coated product exhibits visual homogeneity, i.e., exhibits an increase
15 relative to a blend of the same proportion of the coated substrates of at
least 5 chrorna units (CieLab) or at least five percent (5%) increase in
chroma units when evaluated with an X-Rite MA 68 at 25 from the
specular angle. Preferably, the increase is at least 10 chroma units
(CieLab) and to achieve that result, the average particle size of the
20 smaller of the glass and mica platelets are preferably within about 25%
of the size of the larger of the glass and mica platelets. While it is
preferable to employ C glass, as in the prior art, any type of glass and
morphology can be used in the present invention. Other useful glass
flakes have a thickness of < 1.0 pm and a softening point >800 C.
25 Glass can be classified for example as A glass, C glass, E glass,
and ECR glass. Glass types which fulfill the feature of the requested
softening point are quartz glass, and any other glass composition having
a softening point of >800 C. Glass flakes which fulfill the requirements
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are special glasses like e.g. Schott Duran or Supremax types. The
softening point is defined, according to ASTM C 338 as the temperature
at which a uniform fiber of glass with a diameter of 0.55-0.75 mm and a
length of 23.5 cm increases its length by 1 mm./min when the upper 10
cm. is heated at a rate of 5 C/min.
Examples of useful mixtures of at least two different materials are
in the following table:
FIRST MATERIAL SECOND MATERIAL
A Glass C Glass
A Glass E Glass
A Glass ECR Glass
A Glass Quartz Glass
C Glass E Glass
C Glass ECR Glass
C Glass Quartz Glass
E Glass ECR Glass
E Glass Quartz Glass
Sihcon carbide Mica
Glass spheres Mica
Predominantly iron oxide Glass spheres
containin other oxides
Predominantly iron oxide Mica
containing other oxides
Zinc oxide Glass
Metal or alloy Glass
Ceramic microspheres Mica
Glass bubbles Mica
Suitabke glass flakes are characterized in that they contain an
o average particle size in the range of 5-1000 pm and a thickness of 0.1-
5 pm, preferably of 0.1-0.3 pm. The aspect ratio of glass flakes is in
the range of 10-300, preferably in the range of 50-200.
The substrate coating procedure employed is adjusted such that
the two or more substrate materials coat at substantially the same rate
*Trade-marks
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to thereby develop a coating of similar quality and thickness. This may
involve control of the temperature, reagent addition rate, reagent
identity, substrate pretreatment, and the like. Frequently, this control
is more easily achieved as the platelets become closer to each other in
average size and thickness. The modifications necessary or appropriate
can easily be established by those of skill in this art with a few
preliminary runs to establish the appropriate parameters.
The procedure described above in which the glass and mica
platelets are blended before being coated unexpectedly results in a
io product which exhibits visual homogeneity, showing a uniform color,
which cannot be achieved by forming a blend of previously prepared
coated mica and coated glass platelets. This result is achieved despite
the fact that the mica and glass substrates have different degrees of
transparency, surface chemistry and refractive index and, usually, have
a different thickness.
The calcining of coated glass flakes is typically done in the
neighborhood of 600 C because the glass platelets fuse at about 650-
700 C creating a mass having greatly diminished quality. Surprisingly,
it has been found that a blend of glass and mica, coated with a metal
oxide precursor, is capable of being calcined at temperatures of 650 C
up to about 850 C without causing the glass flakes to fuse. Preferably,
the calcining temperature is about 675 to 825 C and most preferably,
about 800 C. when the metal oxide is Ti02 and about 700 C when the
metal oxide is Fe203.
Another advantage of using the present co-precipitated effect
pigment is the ability to have the color space of the product be the
same for the different materials of the mixture. To achieve an exact
color match of the two different materials and then post blend the
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products is a difficult process and not practical. Factors such as particle
size, surface chemistry, refractive index, and reflectivity of the
substrates influence the final optical properties of the pigments such
that they are difficult to evaluate their equivalent hue values. With the
s present co-precipitated process, the hue values for both substrates are
automatically controlled in the coating process.
The coated substrates, however produced, can be post-treated by
any procedure known in the art. Examples of such treatments can for
instance be found in U.S. 4,134,776, 5,091,011, 5,156,889, 5,326,392,
5,423,912, 5,759,255, and 6,325,846, but are not limited
to those procedures.
Depending on the intended use, the present effect pigment may
benefit from some form of a surface treatment. Non-limiting examples
would be a coupling agent with or without a metal hydroxide for
enhanced exterior stability. Often metal compounds are added as
surface treatments with and without organic compounds to vary the
surface charge of the particles and/or vary the tactile properties.
The resulting pigment can be used in any application for which
effect pigments have been used heretofore such as, for instance, in
cosmetics, plastics, security markings, inks and coatings including
solvent and water borne automotive paint systems. Products of this
invention have an unlimited use in all types of automotive and industrial
paint applications, especially in the organic color coating and inks field
where deep color intensity is required. For example, these pigments
can be used in mass tone or as styling agents to spray paint all types of
automotive and non-automotive vehicles. Similarly, they can be used
on all clay/formica/wood/ glass/metal/enamel/ceramic and non-porous
or porous surfaces. The pigments can be used in powder coating
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compositions. They can be incorporated into plastic articles geared for
the toy industry or the home. Security applications such as inks and
coatings are a valuable use for these products. These pigments can be
impregnated into fibers to impart new and esthetic coloring to clothes
s and carpeting. They can be used to improve the look of shoes, rubber
and vinyl/marble flooring, vinyl siding, and all other vinyl products. In
addition, these colors can be used in all types of modeling hobbies.
The above-mentioned compositions in which the compositions of
this invention are useful are well known to those of ordinary skill in the
to art. Examples include printing inks, nail enamels, lacquers,
thermoplastic and thermosetting materials, natural resins and synthetic
resins. Some non-limiting examples include polystyrene and its mixed
polymers, polyolefins, in particular, polyethylene and polypropylene,
polyacrylic compounds, polyvinyl compounds, for example polyvinyl
15 chloride and polyvinyl acetate, polyesters and rubber, and also filaments
made of viscose and cellulose ethers, cellulose esters, polyamides,
polyurethanes, polyesters, for example polyglycol terephthalates, and
polyacrylonitrile.
For a well-rounded introduction to a variety of pigment
20 applications, see Temple C. Patton, editor, The Pigment Handbook,
volume II, Applications and Markets, John Wiley and Sons, New York
(1973). In addition, see for example, with regard to ink: R.H. Leach,
editor, The Printing Ink Manual, Fourth Edition, Van Nostrand Reinhold
(International) Co. Ltd., London (1988), particularly pages 282-591;
25 with regard to paints: C.H. Hare, Protective Coatings, Technology
Publishing Co., Pittsburgh (1994), particularly pages 63-288. The
foregoing references teach ink, paint and plastic compositions, formulations
and
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vehicles in which the compositions of this invention may be used
including amounts of colorants. For example, the pigment may be used
at a level of 1.0 to 15% in an offset lithographic ink, with the remainder
being a vehicle containing gelled and ungelled hydrocarbon resins, alkyd
s resins, wax compounds and aliphatic solvent. The pigment may also be
used, for example, at a level of 1 to 10% in an automotive paint
formulation along with other pigments which may include titanium
dioxide, acrylic lattices, coalescing agents, water or solvents. The
pigment may also be used, for example, at a level of 20 to 30% in a
plastic color concentrate in polyethylene.
In the cosmetic field, these pigments can be used in the eye area
and in all external and rinse-off applications. Thus, they can be used in
hair sprays, face powder, leg-makeup, insect repellent lotion, mascara
cake/cream, nail enamel, nail enamel remover, perfume lotion, and
shampoos of all types (gel or liquid). In addition, they can be used in
shaving cream (concentrate for aerosol, brushless, lathering), skin
glosser stick, skin makeup, hair groom, eye shadow (liquid, pomade,
powder, stick, pressed or cream), eye liner, cologne stick, cologne,
cologne emollient, bubble bath, body lotion (moisturizing, cleansing,
analgesic, astringent), after shave lotion, after bath milk and sunscreen
lotion.
For a review of cosmetic applications, see Cosmetics: Science and
Technology, 2nd Ed., Eds: M. S. Balsam and Edward Sagarin, Wiley-
Interscience (1972) and deNavarre, The Chemistry and Science of
Cosmetics, 2nd Ed., Vols 1 and 2 (1962), Van Nostrand Co. Inc., Vols 3
and 4 (1975), Continental Press.
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In order to further illustrate the invention, various non-limiting
examples will be set forth below. In these examples, as well as
throughout the balance of this specification, all parts and percentages are
byl
weight and all temperatures are in degrees Centigrade unless otherwise
indicated.
Examples 1-4
A blend of 50 grams of C glass flakes having an average particle
size of about 140 microns (by laser light scattering) were mixed with 50
grams of muscovite mica having an average particle size of about 80
microns. The mixture was dispersed in 750 ml of water and iron and
zinc were introduced in the form of 1 ml of a 39% aqueous solution of
ferric chloride and 7 ml of a 9% aqueous zinc chloride solution. The pH
of the slurry was adjusted to 3.0 using a 35% aqueous sodium
hydroxide solution and the slurry was heated to a temperature of 76 C.
is The pH was then lowered to 1.6 by the addition of hydrochloric acid
and a 40% aqueous solution of titanium tetrachloride was added at a
rate of 100 rnl/hour while the pH was maintained at 1.6 by the addition
of 35% aqueous sodium hydroxide. The titanium introduction was
continued until an appearance of either a white pearl or the interference
colors gold, red and blue had been reached. When the desired endpoint
was achieved, the slurry was filtered on a Buchner funnel and washed
with additional water. The coated platelets were then dried and
calcined at about 800 C.
Microscopic evaluation of the resulting pigments shows the
platelets are coated with a smooth homogeneous layer of titanium
dioxide. The coated pigments were visually homogeneous.
The luster and color of the resulting pigments were evaluated
visually and instrumentally using drawdowns on a hiding chart (Form 2-
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6 opacity charts of The Leneta Company), half of which is black and half
of which is white. A coating on the black part of this chart displays the
reflection color and luster when it is examined specularly, while the
coating on the white portion displays the transmission color when it is
s viewed at non-specular angles. Drawdowns are prepared by
incorporating pigment at a 12% concentration in a nitrocellulose lacquer
and applying the suspension to the black and white chart with a Bird
film applicator bar. The drawdowns prepared in these examples show a
series of vibrant, high-quality colors with high chromaticity and
coverage.
Examples 5-9
100 grams of the glass/mica blend of Examples 1-4 were
dispersed in 330 ml of distilled water which was then heated to 74 C
and the pH adjusted to 1.6 using dilute hydrochloric acid. Then 7 ml of
is an 18% aqueous stannous chloride solution was slowly added followed
by a 40% aqueous solution of titanium tetrachloride at a rate of 100
ml/hour. The pH was maintained at 1.6 during the addition of the tin
and titanium by simultaneously adding a dilute aqueous solution of
sodium hydroxide. The titania addition was continued until either a
white pearl or the interference color gold, red, blue or green was
observed. When the desired endpoint was reached, the slurry was
filtered and washed with additional water and calcined at 800 0C.
Microscopic evaluation of the resulting pigments shows the
platelets are coated with a smooth homogeneous layer of titanium
dioxide. The coated pigments were visually homogeneous.
Drawdowns prepared in the pigments of these examples show a
series of vibrant, high-quality colors with high chromaticity and
coverage.
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Examples 10-17
75 grams of the glass/mica blend of Examples 1-4 were dispersed
in 300 ml of distilled water. The dispersion was heated to 76 C and
the pH adjusted to 3.2 with dilute hydrochloric acid. An aqueous ferric
chloride solution was added to the suspension at 0.2 ml/min. while
maintaining the pH at 3.2 using dilute sodium hydroxide. The ferric
chloride addition continued until a desired color was observed, at which
point the slurry was filtered, washed with water and calcined at 800 C
to yield a ferric oxide coated effect pigment.
Since ferric oxide has an inherent red color, flakes coated with
this oxide have both a reflection color and an absorption color. The
interference color is from interference of light, while the absorption
color is due to the absorption of light. The reflection color changes from
gold to red to blue to green as increasing amounts of iron (III) oxide
are coated on the laminar flakes. As even more iron (III) oxide is
added, thicker coatings of the Fe203 are obtained which yield another
series of interference colors known as second observable interference
colors. The second colors have even higher color intensity than the first
colors. If the coating process is continued even further, a third series of
interference colors can be obtained.
When the iron oxide-coated flakes were drawndown, a series of
vivid, high quality colors are observed. The interference colors realized
in these examples were bronze, first orange, first red, first violet-blue,
first green, second orange, second red, and second green.
Examples 18-20
Titanium dioxide can produce a series of interference colors as the
thickness of the titanium dioxide layer increases. It produces a whitish
reflection which appears pearly or silver initially, and as the Ti02 layer
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becomes thicker, gold, red, blue and green interference colors are
observed. As the coating becomes even thicker, a series of second
observable color is observed. The second colors have more color
intensity than the first colors described in the Examples above.
The second colors were prepared by dispersing 50 grams of the
mica/glass blend used in Examples 1-4 in 333 ml of distilled water. The
pH was adjusted to 1.6 with dilute hydrochloric acid and the suspension
heated to 74 C. Then 7 ml of an 18% stannous chloride solution was
added followed by the addition of 40% titanium chloride at a rate of
io 0.33 ml/min. The pH was maintained at 1.6 by simultaneously adding
dilute sodium hydroxide. The titanium addition continued until the
desired color was achieved, at which point the slurry was filtered,
washed with water and calcined at 800 C. In this manner, the second
colors gold, orange and red are achieved. When drawndown, the
products had higher color intensity than their comparable first
observable interference colors.
Examples 21-25
The procedure of Examples 5-9 was repeated except that the
laminar platelet blend was constituted by 75 parts of muscovite mica
having an average particle size of about 25 microns and 25 parts of C
glass flakes having an average particle size of about 25 microns .
Examples 26-33
The procedure of Examples 10-17 was repeated except that the
laminar platelet blend was constituted by 75 parts of muscovite mica
having an average particle size of about 25 microns and 25 parts of C
glass flakes having an average particle size of about 25 microns .
Example 34-41
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The procedure of Examples 10-17 was repeated except that the
laminar platelet blend was constituted by a blend of 50 grams of platy
aluminum oxide having an average particle size of about 20 microns (by
laser light scattering) and 50 grams of muscovite mica having an
average particle size of about 25 microns.
Example 42
A blend of 150 grams of muscovite mica having an average
particle size of approximately 25 m, were mixed with 50 grams of
glass flake with of nominal thickness of 1 m and a major dimension
(D50) of 20 m. The mixture was dispersed in 2,000 ml of distilled
water and heated to 78 C. At. that temperature, the pH of the slurry
was reduced to 1.5 with dilute HCI solution and 20 grams of a 18%
SnCl4 solution were added at 0.4 ml/min while maintaining the pH at
1.5 with the NaOH solution. Following the addition of the SnCl4
solution, the pH was raised to 3.2 with dilute NaOH and 39% FeCI3 was
added at 1.5 ml/min, until the desired color was achieved The product
was then washed, dried and heat treated at 650 C.
Example 43
The product of Example 42 was dispersed in a commercial
automotive urethane refinish paint formulation and evaluated with an X-
Rite MA 68 for chroma at 25 and 15 from the specular angle. Values
obtained from the sample where the substrates had been preblended
prior to coating and from a sample prepared in a similar fashion with
the same proportions of individually coated substrates are set forth in
the tables below. The preblended sample showed an increase in
chroma of over 10 units (CieLab) at each angle, namely 76.1 vs. 59.7 at
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150 and 62.4 vs.51.8 at 25 .
15 from Specular
L a B C
Example 42 76.8 64.4 40.5 76.1
Blend 80.0 56.5 19.1 59.7
25 from Specular
L a B C
Example 42 56.4 61.7 33.5 62.4
Blend 52.6 48.5 18.3 51.8
Example 44
A blend of 50 grams of platy aluminum oxide having an average
particle size of about 20 microns (by laser light scattering) is mixed with
io 50 grams of muscovite mica having an average particle size of about 25
microns. The mixture is dispersed in 750 ml of water and iron and zinc
are introduced in the form of 1 ml of a 39% aqueous solution of ferric
chloride and 7 ml of a 9% aqueous zinc chloride solution. The pH of the
slurry is adjusted to 3.0 using a 35% aqueous sodium hydroxide
solution and the slurry is heated to a temperature of 76 C. The pH is
then lowered to 1.6 by the addition of hydrochloric acid and a 40%
aqueous solution of titanium tetrachloride added at a rate of 100
ml/hour while the pH is maintained at 1.6 by the addition of 35%
aqueous sodium hydroxide. The titanium introduction is continued until
an appearance of a white pearl had been reached. When the desired
endpoint is achieved, the slurry is filtered on a Buchner funnel and
washed with additional water. The coated platelets are then dried and
calcined at about 800 C.
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Example 45
One hundred grams of an equal weight mixture of glass flakes
(100 p average major dimension) and mica (100 p average major
dimension) is placed in a 1 liter beaker equipped with a magnetic stir
bar and containing 393 grams of a 2% dextrose solution. The slurry is
stirred at room temperature. A solution, containing 7.87 grams of
silver nitrate crystals, 375 ml distilled water and enough 29%
ammonium hydroxide solution to dissolve any precipitate, is rapidly
added to the slurry. The supernatant liquid is tested for silver ion by
the addition of a few drops of concentrated hydrochloric acid. The test
is a visual assessment of any precipitate and/or turbidity and when
none is found, the slurry is filtered and rinsed several times with
distilled water and the presscake is dried at 100 C. to a constant mass.
The dried sample is a lustrous, opaque and silver colored material.
50 grams of the silver-coated material is slurried into 600 ml of
isopropanol at 25 C. To the slurry is added 75 grams of distilled
water, 3.5 grams of 29% NH4OH and 75 grams of tetraethoxysilane.
The slurry is stirred for 7 hours at room temperature and then filtered,
and the product washed and oven dried.
10 grams of this silica-coated material is slurried into 50 grams of
1% dextrose solution. A solution of 0.4 grams of AgNO3r 40 grams of
water and a slight excess of 29% ammonium hydroxide solution is
quickly added to the slurry. When the slurry supernatant liquid tests
negative for silver ion, it is filtered and the product washed and dried at
120 C. The product displays a very clean color flop from blue to violet
upon a change in viewing angle of a lacquer film containing the product,
and the pigment is visually homogeneous.
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Example 46
The pigment of Example 1 can be formulated into a powder eye
shadow as follows:
The following materials are thoroughly blended and dispersed:
Ingredients wt parts
MEARLTALC TCA (Talc) 18
MEARLMICA SVA (Mica) 20
Magnesium Myristate 5
Silica 2
CLOISONNE Red 424C (red Ti02-coated mica) 20
CLOISONNE Violet 525C (violet Ti02-coated mica) 13
CLOISONNE Nu-Antique Blue 626CB
(Ti02-coated mica/iron oxide-coated mica) 2
CLOISONNE Cerise Flambe 550Z (iron
oxide-coated mica) 2
Preservatives & Antioxidant q.s.
MEARLTALC TCA , MEARLMICA SVA, and CLOISONNE
are all registered trademarks of Engelhard Corporation.
Then 7 parts of octyl palmitate and 1 part of isostearyl
neopentanoate are heated and mixed until uniform, at which time the
resulting mixture is sprayed into the dispersion and the blending
continued. The blended material is pulverized and then 5 parts of
Cloisonne Red 424C and 5 parts of the pigment of example 1 added and
mixed until a uniform powder eye shadow is obtained.
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Example 47
The pigment of Example 1 can be formulated into a lipstick as
follows.
The following amounts of the listed ingredients are placed into
a heated vessel and the temperature raised to 85 3 C
wt parts
Candelilla Wax 2.75
Carnauba Wax 1.25
Beeswax 1.00
Ceresine Wax 5.90
Ozokerite Wax 6.75
Microcrystalline Wax 1.40
Oleyl Alcohol 3.00
Isostearyl Palmitate 7.50
Isostearyl Isostearate 5.00
Caprylic/Capric Triglyceride 5.00
Bis-Diglycerylpolyalcohol Adipate 2.00
Acetylated Lanolin Alcohol 2.50
Sorbitan Tristearate 2.00
Aloe Vera 1.00
Castor Oil 37.50
Red 6 Lake 0.25
Tocopheryl Acetate 0.20
Phenoxyethanol, isopropylparaben,
and butylparaben 1.00
Antioxidant q.s.
Then, 14 parts of the pigment of Example 1 are added and mixed
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until all of the pigment is well dispersed. Fragrance is added as desired
and mixed with stirring. The resulting mixture is poured into molds at
75 5 C, allowed to cool and flamed into lipsticks.
Example 48 and Comparative A - -
115 g of muscovite mica with an average particle size of 20 urn were
suspended in 2 liter of deionized water. To this slurry 30 g of glass of a
similar particle size from Nippon Sheet Glass was added and the pH was
adjusted to 1.4 with dilute HCI. To this suspension 2.7 grams of a 77%
solution of SnCI4.5H2O was added and the slurry was heated to 83 degrees
centigrade.
Ti02 was added to the suspension at this time by adding a 40% TiCl4
solution at a rate of 2.8 grams per minute. The slurry was maintained at a
constant pH and temperature during this deposition. The Ti02 addition was
continued until the desired color was achieved. The coating was then filtered,
washed, and calcined for 20 minutes at 800 C.
The Example 48 pigment obtained from this coating procedure, when
compared to another of equal hue value but prepared by dry mixing Ti02
coated mica and Ti02 coated glass (Comparative A), showed improved
chromaticity values as noted below. The phrase "improved chromaticity" as
used herein means displays an increased chromaticity value compared with
a mixture of oxide coated first substrate and oxide coated second different
substrate at the same hue.
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The color characteristics of the two pigments were defined using an X-Rite
MA68 II Multi Angle Spectrophotometer with readings at 15 degrees from
spectral angle. The samples were prepared using 1 gram of pigment in
33.3 grams of NC varnish. The mixture was applied to a black card with a
controlled application device.
X-RITE MA68 II
SPECTRAL COLORIMETRIC DATA AT 15 DEGREES REFLECTANCE
L* a* b* C* h*
EXAMPLE 48 94.6 1.29 50.84 50.86 88.54
COMPARATIVE A 92.72 1.62 46.53 46.55 88.01
DELTA 1.96 -0.32 4.32 4.3 0.53
From the data, it is evident that the chromaticity value ( C*) for the
Example 48 pigment is almost 10% greater than the Comparative A
pigment at the same hue value (h*). The Example 48 product also
exhibited visual homogeneity compared with Comparative A.
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Example 49 and Comparative B
Another advantage of the present co-precipitated 25% mica and
glass blend with Ti02 has been the improvement in bulk color of the final
calcined product. It is known that titanium dioxide coated mica products,
when calcined, have a yellow bulk color. The term "bulk" color refers to
the color observed when looking at the calcined powder. When the glass is
added to the mica slurry, coated, and calcined, the bulk color of the
resulting product is considerably less yellow. The glass being a purer
substrate has less colored impurities, which can add color to the Ti02
coated pigment. This can be documented by observing the color
characteristics of the present glass/mica product coated with Ti02
(Example 49) to a white pearl interference color with those of a similar
coating made with only mica and Ti02 (Comparative B).
Using an X-Rite SP62 model spectrophotometer which is capable of
is measuring the Whiteness Index as set forth in ASTME 313 of powder
substances, the index was measured on a powder of a mica sample coated
with Ti02 (Comparative B) and a 25% glass/75% mica blend coated in a
similar fashion (Example 49).
The Whiteness Index value was 23.3 for the mica sample
(Comparative B) while the Whiteness Index value was 33.9 for the glass
blend sample (Example 49). It is obvious that this is a significant
improvement in the color of the inventive blended glass product. The
phrase "improved Whiteness Index" as used herein means displays an
increased Whiteness Index compared with a mica sample.
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Example 50 and Comparative C
Example 50 was another co-precipitated 25% mica and glass flake
blend with Ti02 was prepared following Example 48 above.
Comparative C was prepared by dry mixing Ti02 coated mica and Ti02
s coated glass flake. The color characteristics of the pigments were
defined using an X-Rite MA68 II Multi Angle Spectrophotometer with
readings at 15 degrees from spectral angle and are as follows
L* a* B* C* h*
COMPARATIVE C 63.96 2.56 -51.06 51.12 272.87
EXAMPLE 51 67.34 4.25 -56.59 56.75 274.29
These results demonstrate that the Example 50 product had improved
chromaticity and visual homogeneity compared with Comparative C.
Example 51
Another co-precipitated 25% mica and glass blend with Ti02 was
is prepared following Example 48 above except that the glass flake
(supplied by Nippon Sheet Glass) had an average particle size of 30
microns. The color characteristics of the pigments were defined using
an X-Rite MA68 II Multi Angle Spectrophotometer with readings at 15
degrees from spectral angle and are as follows
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X-Rite MA 68 II
COLORIMETRIC DATA AT 15 DEGREES REFLECTANCE
L* a* b* C'` h"
Gold 104.34 -1.8 46.82 46.86 92.2
Red 69.67 40.41 -3.82 40.59 354.6
Blue 71.53 -19.33 -41.98 46.21 245.27
Green 92.63 -27.39 7.59 28.42 164.5
Example 52 and Comparative D
Example 52 was another co-precipitated 25% mica and glass flake
blend with Ti02 was prepared following Example 48 above.
Comparative D was prepared by dry mixing Ti02 coated mica and Ti02
coated glass. The color characteristics of the pigments were defined
using an X-Rite MA68 II Multi Angle Spectrophotometer with readings
at 15 degrees from spectral angle and are as follows
L* a* b* C* H*
COMPARATIVE D 71.84 40.40 -2.43 40.47 356.55
EXAMPLE 52 71.91 44.67 -4.77 44.93 353.91
These results demonstrate that the Example 52 product had improved
chromaticity and exhibited visual homogeneity compared with
Comparative D.
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Example 53
A slurry of 210 grams of mica (the median particle size D(50)=50
microns); 30 grams of glass flakes (D(50)=100 microns; supplied by
Nippon Glass); and 2 liters of distilled water was made and stirred at
350 revolutions per minute. The pH was lowered to 1.4 with 1:1HCI.
2.7 grams of 77% SnCl4.5H2O were added dropwise. The composition
was heated to 83 C. 180 grams of 40% TiCl4 at 2.1ml/min were added
while controlling the pH at 1.4 with 35% NaOH. The pH was raised to
8.2 with 35% NaOH. 2500 grams of 28% Na2SiO3.9H2O were added at
3.5 ml/min while controlling the pH at 8.2 with 1:1 HCI. The pH was
lowered to 1.9 with 1:1 HCI at 0.5m1/min. 180 grams of 40% TiCl4
were added at 2.1ml/min while controlling the pH at 1.9 with 35%
NaOH. Product 1 had the following composition: 12.5% Ti02, 33.4%
Si02, 47.3% mica, and 6.8% glass. Product 2 had the following
composition: 13.5% Ti02, 33.0% Si02, 46.8% mica, and 6.7% glass.
Product 3 had the following composition: 16.6% Ti02, 31.8% Si02,
45.2% mica, and 6.4% glass. The X-Rite properties of the resulting
products are as follows.
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Product 1 Product 2 Product 3
15
D65/10 L* 77.01 79.27 82.76
a* -23.64 -25.01 -17.19
b* -12.6 -5.99 10.78
C* 26.79 25.72 20.29
h 208.06 193.46 147.91
25
D65/10 L* 44.13 45.81 48.35
a* -12.28 -12.3 -9.21
b* -8.79 -5.96 3.86
C* 15.1 13.67 9.99
h 215.58 205.83 157.27
45
D65/10 L* 21.69 23.58 25.15
a* -3.72 -3.96 -4.8
b* -9.09 -8.21 -1.76
C* 9.82 9.11 5.11
h 247.76 244.21 200.18
75
D65/10 L* 14.4 15.91 17.16
a* -1.37 -1.36 -2.6
b* -7.99 -7.83 -5.12
C* 8.1 7.95 5.74
h 260.27 260.14 243.02
110
D65/10 L* 11.88 13.25 14.45
a* -0.45 -0.38 -0.46
b* -8.3 -8.27 -7.94
C* 8.31 8.28 7.95
h 266.86 267.39 266.67
s Various changes and modifications can be made in the products
and process of the present invention without departing from the spirit
and scope thereof. The various embodiments that have been disclosed
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herein were for the purpose of further illustrating the invention but were
not intended to limit it.
