U.S. patent application number 13/647621 was filed with the patent office on 2013-02-14 for black pearlescent pigment with a metal layer.
This patent application is currently assigned to SILBERLINE MANUFACTURING CO., LTD.. The applicant listed for this patent is SILBERLINE MANUFACTURING CO., LTD.. Invention is credited to Parfait Jean Marie LIKIBI, Hai Hui LIN, Peter Lloyd REDMOND, Chang XU, Shufang YU.
Application Number | 20130040057 13/647621 |
Document ID | / |
Family ID | 43608614 |
Filed Date | 2013-02-14 |
United States Patent
Application |
20130040057 |
Kind Code |
A1 |
YU; Shufang ; et
al. |
February 14, 2013 |
BLACK PEARLESCENT PIGMENT WITH A METAL LAYER
Abstract
A pearlescent effect pigment having an opaque, dark or black
color is disclosed. The black pearlescent pigment includes a
platelet-shaped non-metal substrate, optionally an oxide layer, a
template layer, and a metal layer. The pearlescent luster of the
disclosed effect pigment is comparable to those of pure pearlescent
effects. The disclosed method provides a cost-effective approach
for the manufacturing of the disclosed effect pigment.
Inventors: |
YU; Shufang; (Orefield,
PA) ; REDMOND; Peter Lloyd; (New Ringgold, PA)
; LIN; Hai Hui; (Naperville, IL) ; XU; Chang;
(Macungie, PA) ; LIKIBI; Parfait Jean Marie;
(Mount Pleasant, SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SILBERLINE MANUFACTURING CO., LTD.; |
Tamaqua |
PA |
US |
|
|
Assignee: |
SILBERLINE MANUFACTURING CO.,
LTD.
Tamaqua
PA
|
Family ID: |
43608614 |
Appl. No.: |
13/647621 |
Filed: |
October 9, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12628779 |
Dec 1, 2009 |
8337609 |
|
|
13647621 |
|
|
|
|
Current U.S.
Class: |
427/304 |
Current CPC
Class: |
C01P 2006/62 20130101;
Y10T 428/2982 20150115; C09C 2200/302 20130101; C09C 2200/304
20130101; C09C 1/0021 20130101; C01P 2004/20 20130101; C01P 2004/03
20130101; C01P 2006/60 20130101; C01P 2004/01 20130101; C09C 1/0015
20130101; C09C 2200/301 20130101; C09C 2220/10 20130101; C01P
2004/61 20130101; C09C 2200/306 20130101; C01P 2006/63 20130101;
C09C 2200/1004 20130101; C09C 2200/102 20130101; C01P 2006/64
20130101; C09C 2200/24 20130101 |
Class at
Publication: |
427/304 |
International
Class: |
B05D 5/06 20060101
B05D005/06; B05D 3/10 20060101 B05D003/10 |
Claims
1. A method of producing the coated pigment comprising a substrate,
the substrate being non-metal; a template layer, the template layer
being an organic monolayer or an organic polymer layer; and a metal
layer; the method comprising: forming a catalyst layer in-situ on
the surface of the substrate; and depositing the metal layer on the
catalyst layer.
2. The method of claim 1, wherein depositing the metal layer
includes depositing a metal onto the surface of the substrate with
electroless deposition.
3. The method of claim 1, wherein forming the catalyst layer and
depositing the metal layer are a one-step reaction.
Description
[0001] The patent or application file contains at least one drawing
executed in color. Copies of this patent or patent application
publication with color drawing(s) will be provided by the Office
upon request and payment of the necessary fee.
[0002] This application is a Division of application Ser. No.
12/628,779 filed on Dec. 1, 2009, which is incorporated by
reference herein in its entirety.
FIELD
[0003] This disclosure generally relates to pigments, and
particularly, to the design of coated pigments and methods of
producing the coated pigments.
BACKGROUND
[0004] Effect pigments having a sequence of interference layers
applied to a transparent substrate are generally known as
pearlescent pigments. The transparent substrate can include natural
or synthetic mica, glass flakes, or metal oxides with a platelet
shape. Mica, which is inexpensive, readily available and easy to
cleave into smooth and thin platelets, is commonly used. In
addition, pigments based on mica are stable towards chemical or
thermal treatment.
[0005] Various techniques have been developed to create
color/luster effects. One approach to making these pigments is to
coat a platelet substrate with a high refractive index metal oxide
layer such as TiO.sub.2, Fe.sub.2O.sub.3, and Zr.sub.2O.sub.3 or
with alternating layers of high and low refractivity as described
in U.S. Pat. No. 6,599,355, U.S. Pat. No. 6,500,251 and U.S. Pat.
No. 6,648,957.
[0006] The use of a metal particle layer as a reflective layer also
has been disclosed. For example, U.S. Pat. No. 5,116,664 discloses
a titanium-mica composite material comprising mica, a first coating
composed of titanium dioxide, and a second coating composed of
powder particles of at least one metal selected from the group
consisting of cobalt, nickel, copper, zinc, tin, gold and
silver.
[0007] U.S. Pat. No. 6,794,037 is directed to a high chroma effect
material comprising a platelet substrate encapsulated with a layer
of silver as light reflective layer, then a spacer layer of metal
oxide, nitride, fluoride, and finally an iron oxide layer.
[0008] U.S. Pat. No. 6,440,208 discloses a color effect material
wherein the platelet substrate is coated first with a light
reflective layer selected from the group consisting of copper,
zinc, an alloy of copper, and an alloy of zinc, then with a second
layer of silicon dioxide or magnesium fluoride, and then a third
layer that is selectively transparent to light.
[0009] U.S. Pat. No. 6,325,847 describes precious metal color
effect materials where a platelet substrate is encapsulated with a
reflective precious metal layer, a second layer of silicon dioxide
or magnesium fluoride and also with a selective transparent third
layer.
[0010] U.S. Pat. No. 7,226,503 relates to an effect pigment
comprising a glass flake with a thickness of .ltoreq.1.0 .mu.m
coated with one or more layers of metal oxides, metal suboxides,
metal oxyhalides and metal fluorides etc.
[0011] U.S. Pat. No. 5,308,394 discloses a pigment that includes a
light-transparent ceramic scaly substrate, a thin compound layer
coated on a surface of the substrate, a rutile layer titanium
dioxide layer formed on a surface of the substrate coated with a
tin compound, a metal compound layer coated on a surface of the
titanium dioxide layer, the metal compound being at least one
selected from the group consisting of Bi, Sb, As, Cd, Mn, Pb and
Cr, and metallic glossy dots formed on the surfaces in a scattering
manner.
[0012] U.S. Pat. No. 6,800,125 discloses an oxide metallic color
effect material comprising a platelet-shaped substrate encapsulated
with a light reflective silver layer, followed by a layer of iron
oxide.
[0013] U.S. Pat. No. 6,582,764 discloses a hybrid inorganic/organic
color effect material that includes a platelet substrate core
coated with a first layer which acts as a reflector to light
directed thereon. The first layer can include an alloy of copper
and zinc, an alloy of aluminum and copper, an alloy of aluminum and
zinc, copper or zinc. The material further includes a second
organic polymer layer, and a selectively transparent third
layer.
[0014] U.S. Pat. No. 6,821,333 discloses a color effect material
comprising a platelet-shaped substrate encapsulated with a highly
reflective layer of metal selected from silver, gold, platinum,
palladium, rhodium, ruthenium etc, a spacer layer of metal oxide,
nitride, fluoride or carbide or polymer, and an outer layer
selected from metals or metal oxides.
[0015] U.S. Pat. No. 6,582,764 is directed to a hybrid/organic
color effect material that includes a platelet-shaped substrate
encapsulated with three layers. The first layer includes either an
alloy of copper and zinc, an alloy of aluminum and copper, or an
alloy of aluminum and zinc. The second layer is an organic layer
and encapsulates the first layer. The third layer is a selectively
transparent layer.
[0016] All these pearlescent pigments have an interference color
effect and a luster effect. However, the hiding power of such
pearlescent pigments is so small that an underlayer cannot be
sufficiently covered. Thus, the pigments are either transparent or
semi-transparent. Moreover, when such pigments are subjected to a
colorimetric appraisal using the CIE lab color space system, the
pigments do not exhibit a black color effect while maintaining a
pearlescent luster effect.
[0017] CIElab values are measured with a Multi-angle
Spectrophotometer at different angles of 15.degree., 25.degree.,
45.degree., 75.degree. and 110.degree.. The reported color
coordinates (L, a*, b*) are related to lightness (L) and color (a*
and b*). The a* is the red/green content and b* is the blue/yellow
content. If a pigment has a low L value with a* and b* values close
to zero at a certain angle, this means that the pigment is black at
that angle. Further, if the same pigment has a very high lightness
(L) value at different angles, this means that the pigment has high
light travel property.
[0018] Blackness (also called Jetness) can be evaluated using a
color dependent black value Mc. Mc is the best jetness parameters
so far, and correlates well with the human perception of increased
jetness. As Mc increases, the jetness of the masstone increases. Mc
is calculated from tristimulus value of illuminating light source
(Xn, Yn, Zn) and the reflected light of sample (X, Y, Z), based on
the following equations:
L=116(Y/Yn).sup.1/3-16
a*=500[(X/Xn).sup.1/3-(Y/Yn).sup.1/3]
b*=200[(Y/Yn).sup.1/3-(Z/Zn).sup.1/3]
Mc=100[log(Xn/X)-log(Zn/Z)+log(Yn/Y)].
An Mc value of 150 or higher is considered highly jet.
[0019] Pigments with black color especially at flop angle with high
light travel exhibiting high jetness have been widely demanded.
Although carbon can be blended so as to create a black effect, such
an addition decreases the pearlescent luster effect
significantly.
[0020] Efforts have been made to obtain dark color effects. U.S.
Pat. No. 5,753,024 for example discloses grey pigments that include
a substrate coated with tin oxide and at least one further metal
oxide and further coated with organic colloids that are calcined at
temperatures of 900-1100.degree. C. Silver-grey semi-transparent
color pigments having mica coated with titania, ferric oxide and
tin oxide are known. Black olive semi-transparent pigments that are
based on mica and coated with cobalt iron oxide and cobalt oxide
are also known. Such pigments have a brown undertone color.
However, the above pigments have an undesirable undertone and do
not have good hiding power.
SUMMARY
[0021] A pearlescent effect pigment having an opaque, dark or black
color is disclosed. The pearlescent luster of the disclosed effect
pigment is comparable to those of pure pearlescent effects. The
disclosed method provides a cost-effective approach for the
manufacturing of the disclosed effect pigment.
[0022] In one embodiment, the dark or black pearlescent pigment
includes a platelet-shaped non-metallic reflector core, an oxide
layer, a template layer, and a metal layer. In one example, the
template layer permits a substantially uniform and smooth coated
surface to be formed. In one implementation, the template layer
includes an organic layer. In one instance, the template layer is
an organic polymer layer grown via Atomic Transfer Radical
Polymerization (ATRP). In another instance, the template layer is
an organic monolayer.
[0023] In another example, the template layer is coated with a
metal layer. The metal layer is substantially continuous. In one
implementation, the metal layer is formed by electroless
deposition. In this instance, the template layer includes amine
groups that contribute to the formation of high density catalyzing
sites. In one example, the high density catalyzing sites permit the
metal layer to be uniform and continuous so as to create opacity.
In one implementation, the amine groups provide metal-ion
complexing sites for sensitizing the substrate. The
metal-ion-sensitized surface of the substrate provides strong
absorption of the catalyst layer to the substrate during the
activating pretreatment for the electroless deposition.
[0024] In one embodiment of the method of producing the dark or
black pearlescent pigment, the method includes forming a catalyst
layer in-situ on the surface of a substrate and depositing a metal
layer on the catalyst layer. In one example, depositing a metal
layer involves electroless deposition, wherein an activation of the
sensitized substrate and reduction of the metal salts are a
one-step reaction.
[0025] The products of the present disclosure are useful in
automotive, cosmetics, industrial or any other application where
pearlescent pigment can be used.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIGS. 1A and 1B illustrate embodiments of the disclosed
coated pigment.
[0027] FIGS. 2A and 2B show the SEM image of the effect pigment
surface at high magnification (100K). FIG. 2A is the image of white
pearlescent pigment surface before coating. FIG. 2B is the surface
after multilayer coating.
[0028] FIG. 3 shows Auger analysis indicating that the Ag layer is
continuous.
DETAILED DESCRIPTION
[0029] A coated pigment including a non-metal substrate, an oxide
layer, a template layer, and a metal layer and a method of
producing the coated pigment are described. The disclosed coated
pigment has a dark or black undertone and has an outstanding hiding
property.
[0030] With reference to FIG. 1A, a coated pigment 10 includes a
substrate 1. In one example, the substrate 1 can be an
encapsulatable platelet. The size of the encapsulatable platelet 1
can have any size that is suitable for forming an effect pigment.
In one implementation, the encapsulatable platelet 1 has a diameter
in the range of 5 .mu.m to 700 .mu.m, and a thickness of 5 nm to
500 nm. The diameter and thickness can be measured using, for
example, Field Emission Scanning Electron Microscopy (FESEM). In
this instance, the diameter is measured as viewed in
cross-sectional top view of the platelet, and the thickness is
measured as viewed in cross-sectional side view of the
platelet.
[0031] In one example, the substrate 1 is a non-metal substrate.
The term "metal" herein means that the oxidation state of the
element metal present in the substrate is zero. The term
"non-metal" herein means that the oxidation state of the element
present in the substrate is other than zero.
[0032] In one instance, the substrate 1 can be formed of any
material that is suitable for forming an effect pigment, including,
but not limited to, glass, silicon oxide, and titanium
dioxide-coated mica. In another instance, the substrate 1 includes
an oxide layer, which can include, but is not limited to, metal
oxides such as SiO.sub.2, TiO.sub.2 and ZrO.sub.2.
[0033] The substrate 1 is coated with a first layer 2. In one
example, the first layer 2 is an oxide layer. The oxide layer 2 can
include, but is not limited to, metal oxides such as SiO.sub.2,
TiO.sub.2 and ZrO.sub.2. In one implementation, the oxide layer 2
is part of a white pearlescent, which is mica that is coated with
TiO.sub.2. In one example, the thickness of the first layer 2 has a
range from a few nm to tens of nm.
[0034] The first layer 2 is further coated with a second layer 3.
In one example, the second layer 3 is a template layer. In one
instance, the template layer 3 is an organic monolayer. The term
"organic monolayer" herein means a layer that includes molecules
with an organic chain. In one example, the organic monolayer 3
includes an aminosilane monolayer and is provided by silanization.
Examples of the aminosilane that can be utilized include
gamma-aminopropyl trimethoxysilane, .gamma.-aminopropyl
triethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane,
gamma-(2-aminoethyl)aminopropylmethyldimethoxysilane, and the like
which contains amino group in the chain or at the end of the chain.
The amino group can be a primary amine, secondary amine or tertiary
amine. In one instance, the amount of the aminosilane included is
in a range of 0.1 to 20% by weight based on the weight of the
starting substrate. In another instance, the amount of the
aminosilane included is in a range of 1 to 50% by weight based on
the weight of the starting substrate. In yet another instance, the
amount of the aminosilane included is in a range of 1 to 20% by
weight based on the weight of the starting substrate. In yet
another instance, the amount of the aminosilane included is in a
range of 1 to 10% by weight based on the weight of the starting
substrate.
[0035] In another embodiment, the template layer 3 is an organic
polymer layer. The organic polymer layer 3 can include polystyrene
(PS), polymethylmetacrylate (PMMA), polymethacrylate (PMA),
2-hydroxy ethyl methacrylate, glycidyl methacrylate, and/or
dimethylamino ethyl methacrylate.
[0036] In one example, the organic polymer layer 3 is formed by
immobilizing initiator molecules onto the surface of the first
layer 2. In one implementation, the initiator includes a surface
active group and an initiator moiety and the surface of the first
layer 2 includes a functional group. The initiator molecule is
immobilized by reacting the surface active group of the initiator
molecule with the functional group on the surface of the first
layer 2. Then, the immobilized initiator molecule is reacted with
one or more polymerizable monomers so that monomers are added to
the initiator moiety and form a polymer chain attached to the
surface of the first layer 2. In one instance, the organic polymer
layer 3 is grown via atomic transfer radical polymerization
(ATRP).
[0037] In yet another example, the polymer chains within the
organic polymer layer 3 are substantially uniform in length such
that the organic polymer layer 3 has a substantially uniform
thickness. In one instance, the organic polymer layer 3 has a
substantially uniform thickness as viewed by Transmission Electron
Microscopy (TEM). In this instance, the thickness of the organic
polymer layer 3 can be in a range from a few nanometers to 100 nm
and have a standard deviation of less than 15% of the average
thickness as measured using a transmission electron microscope at a
magnification between .times.20,000 and .times.100,000.
[0038] In another implementation, the thickness of the organic
polymer layer 3 can be increased or decreased by increasing or
decreasing the reaction time, respectively. In yet another
implementation, the thickness of the organic polymer layer 3 can be
increased or decreased by increasing or decreasing the reaction
temperature, respectively. In still yet another implementation, the
thickness of the organic polymer layer 3 can be increased or
decreased by increasing or decreasing the monomer concentration,
respectively.
[0039] In yet another example, the template layer 3 includes an
amino group. The amino group can be a primary amine or secondary
amine. In the case where the template layer 3 is the organic
polymer layer, the amino group is provided by growing a hydrophilic
coating layer on the polymer chain ends after a desired length of
the initial polymer chains is achieved. In one example, the
hydrophilic layer includes poly(dimethylaminoethyl
methacrylate).
[0040] With reference to FIG. 1B, in another embodiment, a coated
pigment 20 does not include an oxide layer. In one example, the
substrate 1 of the coated pigment 20 includes hydroxyl groups. In
this instance, the substrate 1 is directly coated with the second
layer 3. In one implementation, the substrate 1 is a glass
flake.
[0041] With reference to FIGS. 1A and 1B, the second layer 3 is
further coated with a third layer 4. In one embodiment, the third
layer 4 is a metal layer. The metal layer 4 can include silver,
copper or nickel. In one instance, Auger electron microscopy (AES)
mapping can be used to determine the coverage of the metal layer 4.
In one example, the coverage of the metal layer 4 is substantially
continuous, such that an AES map for a metal within metal layer 4
does not reveal discontinuity in the coverage of the metal layer 4
at a magnification of .times.7500 and a scanned area of 15
.mu.m.times.15 .mu.m using 256 pixel.times.256 pixel density. Here,
the term "substantially continuous" means that Auger Electron
Microscopy at the given magnification for the scanned area of
.times.7500 and 15 .mu.m.times.15 .mu.m using 256 pixel.times.256
pixel density, respectively, cannot resolve discontinuity of the
metal layer 4 such that discrete metal particles are not
observed.
[0042] The metal layer 4 can be formed on the second layer 3 by any
surface-covering techniques suitable for depositing a metal on the
second layer 3. In one example, the metal layer 4 is plated by
electroless deposition.
[0043] Generally, electroless metal deposition involves the use of
a chemical reducing agent to plate a metal from a solution. The
electroless deposition technique allows one to control the
thickness of the coating. One useful plating technique of this type
is to arrange the chemistry such that the kinetics of homogeneous
electron transfer from the reducing agent to the metal ion are slow
within the electroless-plating bath so as to prevent the metal ion
from being reduced in the bulk solution. A catalyst that
accelerates the rate of metal ion reduction is then applied to the
surface to be coated. In this way, metal ion is reduced only at the
surface, and the surface becomes coated with the desired metal. The
metal can be deposited from reduction of aqueous salts of the
metals.
[0044] In one example, the metal layer 4 is formed by reducing a
water-soluble metallic salt. The metallic salt that can be utilized
include silver sulfates, silver hydrochlorides, silver nitrates,
silver carbonates etc., copper sulfate, copper hydrochlorides,
copper nitrates, copper carbonates etc., and nickel sulfate, nickel
hydrochlorides, nickel nitrates, nickel carbonates etc.
[0045] In yet another example, before the metal layer 4 is formed
on the second layer 3 by electroless deposition with water-soluble
metallic salt, the surface of the second layer 3 is activated by a
pretreatment. In one instance, the pretreatment is a
sensitizing-activating treatment that forms a catalyst layer on the
surface of the second layer.
[0046] In one implementation, a sensitizing solution including a
metal ion is utilized. In one example, the metal ion utilized is
Sn(II). In this instance, the amine groups included within the
second layer 3 act as "molecular anchors" that bond the Sn(II) to
the surface of the second layer 3, thereby sensitizing the surface
of the second layer 3. Once the surface of the second layer 3 is
sensitized, the surface is activated by immersion in an aqueous
solution of metallic salt containing Ag, Pd or Pt. This causes a
redox reaction in which the surface is coated with discrete,
nanoscopic Ag, Pd or Pt particles. These particles provide
catalytic sites and together form a catalyst layer including Ag, Pd
or Pt nuclei. Thereafter, the metal layer 4 can be formed on the
surface of this catalyst layer by electroless plating. In
particular, as described above, when the catalyst layer is exposed
to an electroless plating solution, a reducing agent in the plating
solution is oxidized on the surface of the catalyst layer due to
catalytic activity. Metallic salts in the electroless plating
solution are then reduced by the emitted electrons, the metal is
deposited on the surface of the catalyst layer only, and the
continuous metal layer 4 is formed.
[0047] In one example, forming the catalyst layer and depositing
the metal layer are a one-step reaction.
[0048] In one embodiment, the disclosed coated pigment has a dark
or black color such that when the CIElab values of the disclosed
coated pigment are measured using a X-rite MA68II Multi-angle
Spectrophotometer at different angles of 15.degree., 25.degree.,
45.degree., 75.degree., 110.degree., the a* and b* values are close
to zero at the measured angles. In one instance, the a* and b*
values are 0.26 and -0.06, respectively, at 110.degree. and 1.87
and -3.17, respectively, at 15.degree..
[0049] In another embodiment, the disclosed coated pigment exhibits
extreme light travel such that when the CIElab values of the
disclosed coated pigment are measured using a X-rite MA68II
Multi-angle Spectrophotometer at different angles of 15.degree.,
25.degree., 45.degree., 75.degree., 110.degree., the lightness (L
value) is very high at the measured angles. In one instance, the L
value is up to 99.62 at 15.degree. angle and the L value is 5.17 at
an angle of 110.degree..
[0050] In yet another embodiment, the disclosed coated pigment has
high jetness such that when the disclosed coated pigment is
evaluated using a color dependent black value Mc, the Mc value is
over 150 at angles of 75.degree. and 110.degree..
EXAMPLES
Example 1
Monolayer as Template Layer Attachment
[0051] 20 g of TiO.sub.2-coated (anatase) mica with a particle size
of 10-60 .mu.m (D50=19 .mu.m according to Malvern particle size
analysis) were dispersed in 500 mL glycol ether PM with stirring
and after 5 minutes, 1% of .gamma.-aminopropyl trimethoxysilane on
TiO.sub.2-coated mica by weight was added into the dispersion and
stir for 10 minutes, then 1% of water was added as catalyst with
stirring at room temperature. After two hours, the slurry was
filtered and washed with glycol ether PM initially followed by
water.
Example 2
Monolayer as Template Layer Attachment
[0052] Example 1 was repeated except that 10% of
N-(2-aminoethyl)-3-minopropyltrimethoxysilane and 10% of water were
added.
Example 3
Polymer Layer as Template Layer Attachment
[0053] Step 1--Functionalize TiO.sub.2-Coated Mica with ATRP
Initiator
[0054] The reaction was carried out in the fumehood, using a 500 mL
round bottom flask equipped with a magnetic stirring bar and a
condenser.
The following chemicals were added to the reaction flask:
TABLE-US-00001 37.5 g TiO.sub.2-coated mica .sup. 0.3 mL
3-(trimethoxysilylpropyl)-2-bromo-2-methylpropionate .sup. 300 mL
Toluene.
The reaction mixture was heated and was kept under reflux for 18
hours. Once the reaction time was complete, the mixture was cooled
down to room temperature. The flakes were vacuum filtered. Three
washes of toluene (200 mL) were applied.
Step 2--Surface-Initiated Polymerization of Styrene and
Diemthylaminoethyl Methacrylate
[0055] The following reaction was carried out in the fumehood,
using a 100 mL reaction flask equipped with a mechanical stirrer
and a heating mantle.
To the reaction flask, a stir bar and the following reagents were
added:
TABLE-US-00002 CuBr 0.25 g Styrene 40 mL TiO2-coated mica from step
1 6.38 g (containing 4 g of NV) Toluene 40 mL.
[0056] The flask was sealed with a rubber septum and degassed with
N.sub.2 and then the solution was heated to 60.degree. C. In a
separated flask, pentamethyldiethylenetriamine (PMDETA) was
degassed with nitrogen for 30 min. Then, 0.37 mL of degassed PMDETA
was transferred to the reaction flask with an N.sub.2 purged
syringe. The solution was kept at 60.degree. C. for 1 hour before
40 mL of reaction mixture was withdrawn from the reaction mask.
After 1.5 hours of polymerization, 37 mL of degassed
dimethylaminoethyl methacrylate was transferred to the reaction
flask with N.sub.2 purged syringe. The reaction mixture was kept at
60.degree. C. for an additional 1 hour before the reaction was
stopped by cooling the reaction flask to room temperature. The
pigments were separated from the reaction mixture via
centrifugation.
Example 4
Silver Layer Coating on White Pearlescent Pigments
Step 1--Monolayer as Template Layer Attachment
[0057] Same as Example 1.
Step 2--Pretreatment of Template Layer-Coated Pigment
[0058] Template layer-attached white pearlescent pigments from step
1 was dispersed in a solution of 2.5 g SnCl.sub.2 and 2.5 mL HCl in
500 mL water and kept stirring for 20 min pretreatment, and then
filtered.
Step 3--Silver Layer Coating
[0059] The following solutions were used:
[0060] Solution A--5 g AgNO.sub.3 was dissolved in 50 mL water,
NH.sub.4OH 10 mL was added, then more water was added to make a
total volume of 200 mL;
[0061] Solution B--7.5 g of sodium potassium tartrate was dissolved
in 200 mL water.
[0062] The filtered pigment from step 2 was dispersed into 200 mL
water and transferred to 2 L reactor equipped with stirring and
temperature control. The slurry was stirred at 350 rpm. To the
slurry, solution A was first added and was allowed to sit for 5
minutes. A light brown color was observed. Then, solution B was
added and stirred at 350 rpm. The temperature was set at 50.degree.
C. first for 30 min, then increased to 60.degree. C. The total
reaction time was 2.5 hours. Then the slurry was cooled down to
room temperature, filtered, and thoroughly washed with water, and
then washed with isopropyl alcohol once and was air dried. The
resulting powder was black.
Example 5
Step 1--Monolayer as Template Layer Attachment
[0063] Similar to example 1, except 50 g of white pearlescent
pigments was dispersed in 1000 mL glycol ether PM.
Step 2--Pretreatment of Template Layer-Coated Pigment
[0064] Template layer-attached white pearlescent pigments from step
1 was dispersed in a solution of 6.25 g SnCl.sub.2 and 6.25 mL HCl
in 1000 mL water and stirred for a 30 min pretreatment, and then
filtered and washed with water.
Step 3--Silver Coating
[0065] The following solutions were used:
[0066] Solution A--12.5 g AgNO.sub.3 was dissolved in 50 mL water,
NH.sub.4OH 18.75 mL was added, then more water was added to make a
total volume of 200 mL
[0067] Solution B--18.75 g of sodium potassium tartrate was
dissolved in 300 mL water
[0068] The filtered pigment from step 2 was dispersed into 500 mL
water and transferred to a 2 L reactor equipped with stirring and
temperature control. The slurry was stirred at 350 rpm. To the
slurry, solution A was first added and allowed to sit for 5
minutes. Once a light brown color was observed, solution B was
added and was stirred at 350 rpm. The temperature was set at
30.degree. C. first, then gradually increased by 10.degree. C.
every 20 min until reaching 60.degree. C. The total reaction time
was 2.5 hours. Then, the slurry was cooled down to room
temperature, filtered, and thoroughly washed with water, and then
washed with isopropyl alcohol once and air dried. The resulting
powder was black.
Example 6
[0069] 2 g of polymer layer attached white pearlescent pigments
from example 3 was dispersed into a solution of 0.5 g SnCl.sub.2
and 1.0 mL trifluoroacetic acid in 200 mL water and stirred for 20
min as a pretreatment, and then filtered and washed with water.
[0070] The filtered substrate was dispersed into 200 mL water and
transferred to 1 L round bottom flask equipped with a magnetic
stirring bar and a condenser. While the slurry was stirring, two
solutions were made: solution A--0.5 g AgNO.sub.3 dissolved in 20
mL water, NH.sub.4OH 1.0 mL was added, then more water was added to
make a total volume of 100 mL; solution B--3.0 g of sodium
potassium tartrate was dissolved in 100 mL water.
[0071] To the above slurry, solution A was first added and allowed
to sit for 5 minutes. Once a light brown color was observed,
solution B was added and stirred. The temperature was set at
60.degree. C. The total reaction time was 2.5 hours. After the
reaction was complete, the slurry was cooled down to room
temperature, filtered, and thoroughly washed with water, and then
washed with isopropyl alcohol once and air dried. The resulting
powder was black.
Example 7
Evaluation of the Black Pigments
Nitrocellulose Ink Drawdown
[0072] To evaluate the coloristic of the pigments obtained, in each
case 1 g of pigment sample was mixed with nitrocellulose in
isopropyl acetate having a solid content 20% by weight and
dispersed for 30 second in the Speedmixer (DAC 150 FVZ-K) from
FlackTeck Inc. A drawdown bar (#14) was used to prepare drawdowns
of the pigmented varnish on a piece of black and white ink
cardboard. After the film had dried at room temperature, CIELab
values were measured with a X-rite MA68II Multi-angle
Spectrophotometer at an angle difference of 15.degree., 25.degree.,
45.degree., 75.degree., 110.degree.. The reported color coordinates
(L, a*, b*) related to the standard illuminate D65 and a viewing
angle of 10.degree.. L is the lightness, a* is the red/green
content and b* is the blue/yellow content. The measurements were
carried out on single drawdowns over a white background as shown in
Table 1.
TABLE-US-00003 TABLE 1 L a* b* Sample from example 4 (Measuring
angle) 15.degree. 91.76 1.87 -3.17 25.degree. 61.49 1.19 -1.98
45.degree. 25.95 1.11 -0.93 75.degree. 9.89 0.63 -0.33 110.degree.
6.96 0.26 -0.06 Sample from example 5 (Measuring angle) 15.degree.
99.62 3.29 1.17 25.degree. 62.01 2.13 1.28 45.degree. 22.67 1.83
1.14 75.degree. 7.95 1.7 1.51 110.degree. 5.17 1.17 1.34
The Mc values calculated from the above measurement are shown as in
Table 2 below.
TABLE-US-00004 TABLE 2 Mc Sample from example 4 (Measuring angle)
15.degree. 11.28 25.degree. 54.02 45.degree. 133.39 75.degree.
195.62 110.degree. 210.90 Sample from example 5 (Measuring angle)
15.degree. -1.20 25.degree. 49.62 45.degree. 139.46 75.degree.
198.56 110.degree. 215.09
Example 8
Evaluation of the Black Pigments
Refinish Paint System
[0073] To evaluate the resulting black pearls from example 4 in a
paint system, a solvent-borne acrylic system for both base-coat and
clear-coat was used. 8 g of dry black pearls was dispersed in 92 g
of base-coat acrylic resin varnish, and then mixed with the same
volume of solvent blend thinner. The resulting paint was filtered
and sprayed with Siphon on clear ABS plastic chips. The sprayed
chips were baked in the oven at 150.degree. F. for 20 minutes. For
the following clear coat, three parts of clear-coat acrylic resin
varnish was mixed with one part of clear-coat di-isocyanate
hardener and one part of solvent blend thinner. Then the resulting
clear coat was sprayed on the plastic chips, and baked in the oven
at 170.degree. F. for 30 minutes. The sprayed and baked coating
looked black with very good hiding. Same as in example 7, the
CIELab values of chips were measured with a X-rite MA68II
Multi-angle Spectrophotometer at an angle difference of 15.degree.,
25.degree., 45.degree., 75.degree., 110.degree. (in Table 3).
TABLE-US-00005 TABLE 3 Sample from example 4 (Measuring angle) L a*
b* 15.degree. 75.65 2.79 -2.43 25.degree. 51.78 1.65 -1.52
45.degree. 20.00 1.00 -1.00 75.degree. 6.88 0.40 -0.71 110.degree.
4.50 0.17 -0.34
The correspondent Mc values are shown in Table 4 below.
TABLE-US-00006 TABLE 4 Sample from example 4 (Measuring angle) Mc
15.degree. 31.77 25.degree. 70.96 45.degree. 153.69 75.degree.
213.30 110.degree. 226.81
SEM Image Analysis
[0074] Samples were mounted on an aluminum stub via a piece of
double-sided conductive carbon tape using a clean laboratory
spatula. The extra power was purged away by nitrogen before
introduction into the analytical chamber of SEM. Clean tweezers and
gloves were used for all sample handling. The samples were placed
in the analytical chamber which was then evacuated to
<1.times.10.sup.-5 torr. All microscopy was done at a working
distance of 15 mm. FIG. 2A is the SEM image of the white
pearlescent pigment surface before coating and FIG. 2B is the SEM
image of the surface after multilayer coating.
Auger Electron Microscopy (AES) Mapping
[0075] Suspensions were made from dry powder and cast onto clear Si
for analysis. FIG. 3 shows the survey scan of silver of the
deposited sample.
[0076] While the disclosed coated pigments and methods have been
described in conjunction with a preferred embodiment, it will be
apparent to one skilled in the art that other objects and
refinements of the disclosed coated pigments and methods may be
made within the purview and scope of the disclosure.
[0077] The disclosure, in its various aspects and disclosed forms,
is well adapted to the attainment of the stated objects and
advantages of others. The disclosed details are not to be taken as
limitations on the claims.
* * * * *