U.S. patent application number 11/773169 was filed with the patent office on 2008-01-24 for iridescent pigment having high brilliance and high chroma.
Invention is credited to Tamio Noguchi.
Application Number | 20080017076 11/773169 |
Document ID | / |
Family ID | 32212127 |
Filed Date | 2008-01-24 |
United States Patent
Application |
20080017076 |
Kind Code |
A1 |
Noguchi; Tamio |
January 24, 2008 |
IRIDESCENT PIGMENT HAVING HIGH BRILLIANCE AND HIGH CHROMA
Abstract
An iridescent multilayer pigment having at least two or more
layers of metal oxides containing one or more metals selected from
Ce, Sn, Ti, Fe, Zn and Zr which are coated onto the surface of thin
platelet-like substrates. The inventive pigments show high
brilliance and high chroma, in particular in cases in which thin
platelet-like substrates having a fine average particle diameter
are used. The pigment is useful in paints, printing inks, lacquers,
plastics, dopants for laser marking, non-dusting pigment products,
non-dusting pigment granules or cosmetics.
Inventors: |
Noguchi; Tamio;
(Fukushima-ken, JP) |
Correspondence
Address: |
MILLEN, WHITE, ZELANO & BRANIGAN, P.C.
2200 CLARENDON BLVD.
SUITE 1400
ARLINGTON
VA
22201
US
|
Family ID: |
32212127 |
Appl. No.: |
11/773169 |
Filed: |
July 3, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10717926 |
Nov 21, 2003 |
7241503 |
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11773169 |
Jul 3, 2007 |
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Current U.S.
Class: |
106/428 ;
106/401; 106/425; 106/437; 106/450; 106/459; 106/461 |
Current CPC
Class: |
C09C 1/0051 20130101;
C01P 2006/14 20130101; C09D 11/101 20130101; C01P 2006/65 20130101;
C01P 2004/03 20130101; C09C 1/0021 20130101; C01P 2006/64 20130101;
C01P 2006/66 20130101; C09D 11/037 20130101; C01P 2006/62 20130101;
C09D 11/17 20130101; Y10T 428/2982 20150115; Y10T 428/2991
20150115; C01P 2006/63 20130101; C01P 2006/12 20130101; C09C 1/0015
20130101; C09C 1/0024 20130101; C09C 2200/505 20130101 |
Class at
Publication: |
106/428 ;
106/401; 106/425; 106/437; 106/450; 106/459; 106/461 |
International
Class: |
C04B 14/00 20060101
C04B014/00; C08K 3/00 20060101 C08K003/00; C09C 1/22 20060101
C09C001/22 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 21, 2002 |
JP |
2002-338344 |
Claims
1. The method according to claim 10, wherein the iridescent pigment
comprises a platelet shaped substrate and coated thereon at least
two layers of metal oxides, each of said metal oxide layers
comprising one or more of Ce, Sn, Ti, Fe, Zn and Zr.
2. The method according to claim 1, wherein a layer adjacent to the
substrate is a metal oxide layer comprising one or more metals
selected from the group consisting of Ce, Sn and Fe, and wherein
said pigment comprises one or more repeating set of metal oxide
layers of Sn followed by Ti.
3. The method according to claim 1, wherein a layer adjacent to the
substrate is a metal oxide layer comprising Sn, and the layer
thereon is a metal oxide layer comprising Ti.
4. The method according to claim 1, wherein a metal oxide layer
comprises an alkali metal and/or an alkaline earth metal.
5. The method according to claim 4, wherein the alkaline earth
metal is Mg and/or Ca.
6. The method according to claim 1, wherein the specific surface
area of the pigment is 10 m.sup.2/g or less.
7. The method according to claim 1, wherein the pigment has a pore
amount of 0.006 ml or less for each 1 m.sup.2 of the surface area
of the platelet shaped substrate.
8. The method according to claim 1, wherein the pigment has a
specific surface area is 10 m.sup.2/g or less and the pore amount
of 0.006 ml or less for each 1 m.sup.2 of the surface area of the
platelet shaped substrate.
9. The method according to claim 1, wherein the platelet shaped
substrate is mica, synthetic mica, silica flakes, alumina flakes,
glass flakes, thin platelet-like iron oxide or metal flakes.
10. A method for preparing an iridescent pigment comprising
preparing a suspension, said suspension comprising platelet shaped
substrates and one or more water-soluble polymers and/or
water-soluble nitrogen compounds, followed by coating a metal
hydrate layer onto the surface of the substrates by adding one or
more metal salts and a basic aqueous solution to said
suspension.
11. A method according to claim 10 comprising adding to the
suspension one or more alkali metal compounds and/or alkaline earth
metal compounds, optionally said one or more alkali metal compounds
and/or alkaline earth metal compounds are in an aqueous solution
when added to the suspension.
12. A method according to claim 10, wherein the water-soluble
polymer is polyethylene glycol.
13. A method according to claim 10, wherein the water-soluble
polymer is a water-soluble surfactant.
14. (canceled)
15. (canceled)
16. The method according to claim 1, wherein the average particle
diameter of the substrate is 30 .mu.m or less.
17. The method according to claim 1, wherein the average particle
diameter of the substrate is 20 .mu.m or less.
18. The method according to claim 1, wherein the average particle
diameter of the substrate is 10 .mu.m or less.
19. The method according to claim 10, wherein the water-soluble
nitrogen compound is urea, buret, guanidine or a water-soluble
amine.
20. A method according to claim 10, wherein the basic compound is
sodium hydroxide or potassium hydroxide.
21. The method according to claim 3, wherein the pigment comprises
one or more repeating metal oxide layers of Sn followed by Ti.
22. The method according to claim 1, wherein the pigment comprises
a layer sequence of metal oxide layers of Sn--Ti--Sn.
23. A method according to claim 10, wherein the metal salt is a
secondary tin salt and no oxidizing agent is added to the
suspension.
24. The method according to claim 1, wherein the pigment comprises
a layer sequence of metal oxide layers of Fe--Sn--Ti--Sn--Ti.
25. The method according to claim 1, wherein the pigment comprises
a layer sequence of metal oxide layers of Fe--Sn--Fe/Ti.
26. (canceled)
Description
[0001] Iridescent pigment having high brilliance and high chroma
and preparation method for the same.
[0002] The present invention relates to an iridescent pigment
having high brilliance and high chroma, and in particular relates
to an iridescent pigment exhibiting excellent brilliance and
chroma. Use of a thin platelet-like substrate having a fine
particle diameter preferred. The present invention further relates
to a preparation method for the same and the use thereof.
[0003] Iridescent pigments (pearl-luster pigments) exhibiting pearl
luster using mica etc. as thin platelet-like substrates, e.g.,
platelet-shaped substrates, on the surface of which titanium oxide,
iron oxide, etc. is formed as a metal oxide coating layer having a
high refractive index have hitherto been known and widely used in
plastics, paints, inks, cosmetics, etc. Such iridescent pigments
exhibit color by means of the interference effect of the reflected
light from the surface of the metal oxide coating layer having a
high refractive index and the reflected light from the boundaries
of the coating layer and the thin platelet-like substrates
(JP-B-43-25644 and JP-B-49-3824).
[0004] Conventional iridescent pigments are those using thin
platelet-like substrates of mica etc. with an average particle
diameter of 2 to 100 .mu.m, a metal oxide such as titanium oxide
and/or iron oxide etc. is coated thereon; these pigments do not
however have sufficient brilliance and chroma. The causes for this
can be divided into 1) a natural cause which comes from the
particle shape of the fact that luster decreases as a result of the
increase of the ratio of light scattering due to the increase of
particle edges along with the reduction of the particle diameter
and the relative decrease of the ratio of parallel light reflected
from the thin platelet-like particle planes surface; and 2) a
technical cause, based on the coating conditions and method, which
has its origin in the insufficient smoothness of the reflective
surface, i.e. the surface of the coated layer because, when coating
metal hydrates which are the precursors of the coated metal oxides,
the particles of the thin platelet-like substrates are
agglomerated, these overlapped parts are not coated with metal
hydrates and the density of the metal oxide coating layer is not
sufficient (the optical refractive index is reduced because of the
existence of roughly coated parts).
[0005] Thus, it naturally gets more difficult to obtain a uniformed
metal oxide coating layer on the particle surface of each thin
platelet-like substrate as the thin plated-like particle is finer,
the interfacial energy is bigger, its agglomeration is increased.
Therefore, the pearl-luster pigments obtained cannot exhibit
sufficient brilliance and chroma.
[0006] Much research and development for increasing brilliance and
for improving the chroma of interference colors has already been
conducted and disclosed. For example, pigments to which sintering
aids are added in the production process in order to increase the
refractive index of the coated metal oxides (JP-A-10-279828),
pigments in which the crystals of the coated metal oxide particles
are altered in order to increase the optical refractive index
(change to rutile-type coated TiO.sub.2) (JP-B-54-34010,
JP-B-56-43068 and JP-A-62-34963), and multiple coating layer
pigments with various metal oxides designed to improve brilliance
by multiplying interference by increasing the number of coating
layer interfaces and the light reflecting area (JP-A-2000-501774,
JP-A-2000-517374, and JP-A-2001-5210296) have been disclosed.
[0007] However, with decreasing particle diameter of the thin
platelet-like substrates, a sufficient effect with satisfactory
brilliance and chroma cannot be obtained by these techniques
either.
[0008] On the other hand, in the market actually, it is increased
the demands, such as an iridescent pigments without particle
feeling with a depth feeling especially in the painting sector use
and the demand for iridescent pigments with fine particle diameter
exhibiting high brilliance and high chroma in the ink sectors use
in which the particle size is restricted such as the offset
printing and writing appliance ink sector.
[0009] Thus, an object of the present invention is to solve the
above-mentioned problems of the prior art and to provide an
iridescent pigment exhibiting high brilliance and high chroma in
particular even in cases that thin platelet-like substrates having
a fine average particle diameter are used.
[0010] The inventors found that by forming a plurality of metal
hydrate layers consisting mainly of specific metals on thin
platelet-like substrates, it is possible to obtain a homogeneous
metal hydrate coating layer on the surface of the thin
platelet-like substrates by reducing the agglomeration of the thin
platelet-like substrates and that it is possible to improve the
refractive index by reducing the pore amount of the coating
layer.
[0011] Thus, the present invention relates to an iridescent pigment
wherein multilayer coats having at least two or more layers of
metal oxides comprising one or more metals selected from the group
consisting of Ce, Sn, Ti, Fe, Zn and Zr is coated onto the surface
of thin platelet-like substrates.
[0012] The present invention further relates to the above-mentioned
iridescent pigment wherein the lowest layer of the multilayer coats
is a metal oxide layer comprising metals selected from the group
consisting of Ce, Sn and Fe and wherein said multilayer coats
comprises one or more multilayer units made from a metal oxide
layer comprising Sn and attached to the upper face thereof a metal
oxide layer comprising Ti.
[0013] The present invention also relates to the above-mentioned
iridescent pigment wherein the lowest layer is a metal oxide layer
comprising Sn and attached to the upper face thereof a metal oxide
layer comprising Ti.
[0014] The present invention further relates to the above-mentioned
iridescent pigment wherein the multilayer coats has a metal oxide
layer comprising an alkali metal and/or an alkaline earth
metal.
[0015] The present invention also relates to the above-mentioned
iridescent pigment wherein the alkaline earth metal is Mg and/or
Ca.
[0016] The present invention further relates to the above-mentioned
iridescent pigment wherein the specific surface area is 10
m.sup.2/g or less and the pore amount is 0.006 ml or less for each
1 m.sup.2 of the surface area of the thin platelet-like
substrate.
[0017] The present invention also relates to the above-mentioned
iridescent pigment wherein the thin platelet-like substrate is
selected from the group consisting of mica, synthetic mica, silica
flakes, alumina flakes, glass flakes, BiOCl flakes, thin
platelet-like iron oxide and metal flakes.
[0018] The present invention further relates to a preparation
method for an iridescent pigment containing therein thin
platelet-like substrates are treated to be high dispersed
suspension is obtained by adding water-soluble polymers and/or
water-soluble nitrogen compounds to a suspension of said substrates
and therein, thereafter, a metal hydrate layer is coated onto the
surface of the treated substrates by adding metal salts and a basic
aqueous solution to said suspension.
[0019] The present invention also relates to the above-mentioned
preparation method containing therein an aqueous solution of alkali
metal compounds and/or alkaline earth metal compounds is
additionally added simultaneously with adding metal salts and a
basic solution or directly thereafter.
[0020] The present invention further relates to the above-mentioned
preparation method wherein the water-soluble polymer is
polyethylene glycol.
[0021] The present invention also relates to an iridescent pigment
obtained by the above-mentioned preparation method.
[0022] The present invention further relates to the use of the
above-mentioned iridescent pigment in paints, printing inks,
plastics, dopants for laser marking, non-dusting pigment products,
non-dusting pigment granules or cosmetics.
[0023] The present invention, by adopting a specific structure
wherein multiple layers of metal oxides comprising a specific metal
are coated onto the surface of a thin platelet-like substrate,
provides an iridescent pigment having high brilliance and high
chroma, wherein the coating layers coated onto the thin
platelet-like substrate are homogeneous, which realizes high
brilliance and high chroma in particular even in cases that thin
platelet-like substrates having a small average particle diameter
are used. The iridescent pigment according to the present invention
realizes high brilliance and high chroma because of a smooth
surface characterized in that the pore amount is reduced and small
metal oxide particles in the nanometer range are densely and
uniformly coated onto the substrate surface.
[0024] Further, the method according to the present invention,
wherein metal oxide layers are coated onto the surface of a thin
platelet-like substrate by means of a simple wet process method,
makes it possible to produce the above-mentioned iridescent pigment
having high brilliance and high chroma. According to the method of
the present invention, it is possible to obtain a surprisingly
uniformly coating layer on the surface of a thin platelet-like
substrate by reducing the agglomeration of the thin platelet-like
substrates, even with thin platelet-like substrates having a fine
particle diameter. In conventional methods for producing iridescent
pigments, wherein metal hydrates from an aqueous solution of metal
salts and a basic solution are coated under acidic conditions of pH
1.5 to pH 3.0 onto thin platelet-like substrates by suspending the
thin platelet-like substrates having fine particles with an average
particle diameter of 30 .mu.m or less such as mica in water, it is
difficult to uniformly coat metal hydrates onto a mica surface
since mica agglomerates because being near to its isoelectric point
(the isoelectric point of muscovite: pH=0.95) to this coating pH.
There is also the problem that the isoelectric point of the coated
metal hydrates is also close (the isoelectric point of TiO.sub.2
(rutile): pH=4.7) to this coating pH and that it is impossible to
coat a thin layer onto the mica surface because the metal hydrates
also agglomerate.
[0025] On the other hand, according to the method of the present
invention, it is possible to surprisingly increase the dispersion
stability of the suspension of thin platelet-like substrates by
adsorbing surfactants and water-soluble polymers on the surface of
the thin platelet-like substrates. Further, by the chelating action
of surfactants and water-soluble polymer compounds with metal ions,
it is possible to coat dense primary metal hydrate particles on the
surface of thin platelet-like substrate and to produce an
iridescent pigment having high brilliance and high chroma.
[0026] Hereinafter, the present invention along with the
preparation method adopted therein will be explained in greater
detail.
(1) Process A: adding water-soluble polymers or water-soluble
nitrogen compounds to a suspension of thin platelet-like substrates
and heating it (surface treatment of the thin platelet-like
substrate)
[0027] In this process, the surface of thin platelet-like
substrates is treated by suspending the thin platelet-like
substrates in water and by adding water-soluble polymers and/or
water-soluble nitrogen compounds thereto. Due to this process the
dispersibility of the thin platelet-like substrates in an aqueous
solution can be increased.
[0028] Examples of thin platelet-like substrates used in the
present invention include mica, synthetic mica, silica flakes,
alumina flakes, glass flakes, BiOCl flakes, thin platelet-like iron
oxide (MIO: micaceous iron oxide), various metal flakes, passivated
metal flakes (e.g., passivated aluminum flakes and passivated
titanium flakes), stainless steel flakes, graphite, etc.
[0029] An example of the use of silica flakes is in JP-A-07-500366,
an example of the use of alumina flakes is in JP-A-07-260959, and
an example of the use of passivated aluminum flakes is in Japanese
Patent Application No. 2001-234461. Mica is preferred because of
its easy availability and its wide use. In sectors where hiding
power is required, opaque thin platelet-like substrates, such as
various metal flakes, passivated metal flakes (Japanese Patent
Application No. 2001-234461), graphite, etc., are preferred.
[0030] The size of the particle diameter of the thin platelet-like
substrate used can be selected at will in the range adopted for
conventional iridescent pigments; however, particles having an
average diameter of 2 to 100 .mu.m, an aspect ratio (average
diameter to average thickness) of 5 to 200 or a preferred aspect
ratio of 10 to 100 are appropriate because of its wide use. The
average particle diameter at which the effect of the present
invention is particularly evident, compared to conventional
iridescent pigments, is 30 .mu.m or less, preferably 20 .mu.m or
less and even more preferably 10 .mu.m or less. When the particle
diameter decreases, the tendency of the thin platelet-like
substrates to agglomerate increases, and for preventing this
agglomeration, the effect of the present invention becomes more
remarkable.
[0031] The thin platelet-like substrate selected above is suspended
in water and water-soluble polymers and/or water-soluble nitrogen
compounds are added. This is done for the purpose of the surface
treatment preventing the agglomeration between the thin
platelet-like substrates in the suspension, which is the principal
object of the present invention. By this means it is possible to
reduce the parts on the surface of the thin platelet-like
substrates not coated by metal hydrates in the coating process
performed thereafter.
[0032] Examples of the water-soluble polymers used in the present
invention include water-soluble nonionic surfactants such as the
alkylene oxide polymerized one with various alcohols. Examples
include for example polyalkylene glycols when bifunctional alcohols
such as ethylene glycol and propylene glycol etc. are used.
Specific examples include polyethylene glycol and polypropylene
glycol as well as random polymers and block polymers thereof. From
the viewpoint of water solubility, polymers with many
oxyethylene-base structural parts (polymers with good hydrophylic
properties) are selected as far as possible as polyethylene glycol
random or block polymer. Any of these polymers, as long as it is
soluble in water, may be selected. Polyethylene glycol with a
molecular weight of 5000 or less is particularly preferred.
Water-soluble polymers can be used as an aqueous solution
separately prepared beforehand or, if their water solubility is
high, they can also be added directly to the suspension. For
dissolving the polymers in water, those which are in the liquid
state at room temperature are most preferred.
[0033] The amount of water-soluble polymers used varies according
to the concentration and particle size of the thin platelet-like
substrates in the suspension; however, 0.1 to 5 weight parts for
100 weight parts of the thin platelet-like substrates are preferred
when thin platelet-like substrates with an average particle
diameter of 2 to 100 .mu.m are used. Since the unit surface area
increases in cases of fine particle diameters, it may of course be
necessary to increase the amount within this range of these
particles. In the present invention, it is possible to use
water-soluble nitrogen compounds instead of or together with
water-soluble polymers.
[0034] Examples of water-soluble nitrogen compounds include for
example urea, buret, guanidine and water-soluble amines.
Water-soluble amines include primary, secondary, tertiary amines,
diamines as well as salts thereof and quaternary amine salts.
Examples of water-soluble amines include e.g.
(poly)hydroxyalkylamine salts, polyoxyethyleneamine salts,
hydroxyamine, salts thereof, polyoxyethyleneamine, ethylenediamine
and salts thereof. The amount of water-soluble nitrogen compounds
used is identical to the amount of water-soluble polymers mentioned
above. It is also possible to use the water-soluble polymers
together with the water-soluble nitrogen compounds.
[0035] Next, the pH is adjusted to a predetermined value for the
various aqueous solutions of metal salts added in the following
processes (hereinafter called "process B" and "process D") by using
mineral acids such as hydrochloric acid, sulfuric acid, nitric
acid, etc. or basic compounds of caustic soda and caustic potash,
and the temperature is raised to about 85.degree. C. For example,
when using Ce salt the pH is adjusted in the range from 7 to 9, for
Ti and Sn salts it is adjusted in the range from 1.5 to 2.0 and for
Fe salt it is adjusted in the range from 2.5 to 3.5. These pH
values are, according to the present invention, the preferred
ranges for coating the respective hydrated metal salts onto the
thin platelet-like substrates in the future process.
(2) Process B: simultaneously adding metal salts and basic
solutions for coating the thin platelet-like substrates while
stirring and while maintaining a predetermined pH, and repeating
this process for each metal salt to be coated.
[0036] In this process the desired types of aqueous solutions of
metal salts and basic aqueous solutions that have been prepared
separately beforehand are simultaneously added to and hydrolyzed
successively and/or repeatedly, as desired, in the suspension of
thin platelet-like substrates obtained in process A, and are
deposited as a plurality of coating layers of the respective metal
hydrates which are the precursors of the metal oxide layers. In
this process, the metal hydrate layers to be the multilayer coats
are coated onto the thin platelet-like substrates.
[0037] Examples of metal salts used in the present invention
include Ce salt, Sn salt, Ti salt, Fe salt, Zn salt and Zr salt.
Among these, Ce salt, Sn salt and Fe salt are preferred and can be
used as the "lowest layer" which is coated directly onto the
surface of the thin platelet-like substrates. This is to improve
the density of the other metal hydrate layers coated onto this
layer. Ti salt, Zr salt and Zn salt are used for coating layers
other than the lowest layer with the aim of fully showing
interference colors, because the refractive index of metal oxides
finally obtained from these metal salts is high and because there
is no absorption of light at specific visible wave lengths. Ce salt
used in the lowest layer is not only in order to increase density,
it can also be used as the other coating layers than it with the
aim of showing blue which is the inherent color (masstone) of metal
oxides thereof. Sn, too, is not only used in the lowest layer, it
can also be used in other coating layers than it for showing
interference colors because metal oxides thereof have a high
refractive index. As to Fe salt, it, too, is not only used in the
lowest layer in order to increase density, it can also be used in
other coating layers than it for showing interference colors
because metal oxides thereof have a high refractive index; and
since the inherent color (masstone) of these metal oxides is red,
it can further be used in coating layers other than the lowest
layer with the aim of obtaining interference colors and reddish
color tones.
[0038] Any of the above-mentioned metal salts may be used as long
as it is water-soluble. It is understood that chlorides, sulfates,
nitrates, and acetates thereof are mainly used. Moreover, in the
present invention, it is possible to use these metal salts, even if
they are not water-soluble in themselves, in an aqueous solution by
using mineral acids and by lowering the pH.
[0039] Examples of metal salts used in this process include Ce
salts such as cerium chloride, cerium sulfate, cerium nitrate; Sn
salts such as tin dichloride, tin tetrachloride, primary and
secondary tin sulfate, primary and secondary tin nitrate. Examples
of Ti salts include for example titanium tetrachloride, titanyl
sulfate, titanium sulfate, titanium trichloride, etc. Examples of
Fe salts include primary and secondary iron chloride, primary and
secondary iron sulfate, secondary iron nitrate; examples of Zn
salts include zinc chloride, zinc sulfate, zinc nitrate; and
examples of Zr include zirconium oxychloride, zirconium sulfate and
zirconium nitrate.
[0040] In the method adopted in the present invention for coating
metal hydrates onto the thin platelet-like substrates that have
been subjected to a surface treatment in process A, the
above-mentioned types of aqueous solutions of metal salts and basic
aqueous solutions separately prepared beforehand are simultaneously
used and added to a suspension while maintaining a predetermined
pH. From the viewpoint of availability, sodium hydroxide and
potassium hydroxide are preferably used as basic compounds. It is
also possible to use suitable aqueous ammonium solutions and other
water-soluble amines etc. However, sodium hydroxide and potassium
hydroxide are preferred, because in the present invention they
additionally have the role of sintering aids of alkali metal
compounds, as described below (in process D). Namely, when alkali
metal hydroxides are used as basic compounds, this is not only for
adjusting the pH, but also at the same time for the sintering.
[0041] The combination of the plurality of metal oxide coating
layers preferably adopted in the present invention can be selected
at will within the range of the above-mentioned conditions;
however, the following case can be particularly given as
example.
[0042] Namely, the coating according to the present invention which
is a plurality of metal oxide coating layers wherein two layers are
coated in the order of SnO.sub.2 as the lowest layer followed by
TiO.sub.2, and wherein the multilayer unit made from these two
layers (SnO.sub.2-- TiO.sub.2) repeated one or more times is
preferred for obtaining the iridescent pigment having high
brilliance and high chroma which is an object of the present
invention.
[0043] To obtain the iridescent pigment made from this combination
of layers, predetermined amounts of the precursors, i.e. the
aqueous solution of Sn salt and the aqueous solution of Ti salt,
for obtaining the desired hues are alternately and successively
added to the suspension that has passed process A. The suitable pH
range for adding these aqueous solutions of Sn salt and Ti salt is
1.5 to 2.0.
[0044] When the hydrated Ti coating layer is formed, the particles
diameter of the Ti hydrates is reduced and the Ti hydrates are
changed to the rutile-type because of the Sn hydrates existing
under this layer. Consequently, by successively coating alternating
layers, the layer of Ti hydrates is in contact with Sn salt above
and below; therefore the Ti hydrates are changed to the rutile type
more effectively than in the prior art and, as a result thereof, it
is possible to obtain TiO.sub.2 coating layers with a high
refractive index. In JP-B-56-43068 cited in the prior art above,
the order of the coating layers is rutile/SnO.sub.2/rutile; on the
contrary to this SnO.sub.2, which is coated by using primary tin
salt together with an oxidizing agent, the SnO.sub.2, used in the
present invention as the lowest layer, is different in that
secondary tin salt is directly used without using an oxidizing
agent, which is effective for forming a dense upper layer and
which, at the same time, is also advantageous to have a
reutilization activity.
[0045] Moreover, a metal oxide coating can be given as example
wherein the lowest layer is CeO.sub.2 or Fe.sub.2O.sub.3 and
wherein the upper layers thereof, i.e. a SnO.sub.2 layer followed
by a TiO.sub.2 layer (SnO.sub.2--TiO.sub.2), are repeated at least
one time. For this coating an aqueous solution of Ce salt or an
aqueous solution of Fe salt is added, subsequently an aqueous
solution of Sn salt followed by an aqueous solution of Ti salt are
added. The pH for this coating is determined according to the
conditions described above.
[0046] When Ce salt is used to generate a blue masstone, the
aqueous solution of Ce salt is not only added for the lowest layer,
but it can also be used between the other metal hydrate layers
coated as upper layers.
[0047] The present invention further comprises, as iridescent
pigment exhibiting interference colors, a pigment with a multilayer
coating combining a Fe.sub.2O.sub.3 layer, as the lowest layer,
with a SnO.sub.2 layer and a TiO.sub.2 layer (SnO.sub.2--TiO.sub.2)
coated as upper layers thereon. This iridescent pigment is obtained
by using an aqueous solution of Fe salt to produce metal hydrates
thereof as the lowest layer and by coating the two types of aqueous
solutions of metal salt in any order as upper layers thereon.
Preferably, the combination is added in the sequence of Fe salt for
the lowest layer, followed by Sn salt and Ti salt repeated at least
one time in the order of Sn salt--Ti salt, while maintaining the pH
suitable for the production of the respective metal hydrates
described above. By using Fe salt abundantly it is further possible
to obtain iridescent pigments showing interference colors with
reddish masstones. For the purpose of obtaining these masstones, Fe
salt is not only used for the lowest layer, but it can also be used
in intermediate layers of the SnO.sub.2 and TiO.sub.2 layers coated
as upper layers thereon.
[0048] An example of a pigment having a composite metal oxide
coating layer is the case in which Fe salt is added for the lowest
layer followed by Sn salt and by Fe/Ti salts. Here, "Fe/Ti salts"
represent a mixed aqueous solution of Fe salt and Ti salt. In this
case, in which the outermost layer is of composite metal oxides of
Ti and Fe, the iridescent pigment exhibits an interference color
having a masstone of a yellow hue with high brilliance.
[0049] In the present invention, the amount of aqueous solution of
metal salt added is the amount for obtaining the thickness of the
metal oxide coating layer that will exhibit the greatest chroma of
the desired interference color.
[0050] Concretely this means that the color intensity of each hue
(the chroma C is calculated according to formula 1 from the value a
which is (Formula 1) {square root over (a.sup.2+b.sup.2)} the
red-green index and the value b which is the yellow-blue index) is
simulated in accordance with the interference principle of light
(whereby interference increases due to the phase matching between
the surface reflection of light at the wavelength of the intended
hue and (each) boundary reflection) by means of computer analysis
(e.g. with TF-Calc produced by Software Spectra Inc.). Then the
conditions that will produce the greatest chroma of the desired hue
are selected and the amount of aqueous solution of metal salt
predetermined on the basis of the area to be coated so as to obtain
the thickness for the intended hue is added to the suspension. In
this way, each of the above-mentioned aqueous solutions of metal
salt is added, and the amount of aqueous solution of metal salt is
determined on the basis of the chroma actually obtained.
[0051] For example, when coating a titanium oxide layer onto e.g. a
thin platelet-like substrate of mica with an average particle
diameter of 5 .mu.m and showing a yellow interference color, the
amount of aqueous solution of titanium salt to obtain a thickness
of 200 to 220 nm is added to the suspension. Further, when coating
a composite metal oxide layer, the aqueous solution in which the
metal salts are mixed is adjusted beforehand and added in the same
way as above. In the present invention, in order to form a
plurality of the above-mentioned metal hydrate layers, the various
types of aqueous solutions of metal salt are adjusted beforehand
and added, successively and repeatedly, to the suspension.
(3) Process D: coating a hydrate layer of alkali metal compounds or
of alkaline earth metal compounds at the same time or after adding
the various types of metal salts in process B
[0052] This process is an additional process of process B in which
an aqueous solution of metal compounds called "sintering aid" is
added to accelerate the sintering by means of drying and
calcination (described in process C below).
[0053] Examples of this sintering aid include alkali metal
hydroxides (mentioned above) of Na, K etc., and alkaline earth
metal salts of Ca, Mg, etc. As alkaline earth metal salts,
chlorides, hydrochlorides and nitrates thereof can be mentioned;
however, as long as they are water-soluble when added any of them
may be used. Among the alkaline earth metal salts, it is preferred
to use Mg salt and Ca salt. In the present invention, preferably
the outermost layer of the plurality of metal hydrate layers is
coated with a sintering aid. A method of preparation comprises
adding a sintering aid simultaneously with the adding of the
various types of aqueous solutions of metal salts or directly after
adding the respective aqueous solution of metal salt in process B.
Having passed through this process, the sintering aid, in the
drying and calcination in process C hereafter, produces a sintering
effect, reduces the pore amount of the plurality of metal oxide
layers and contributes to the increase of the refractive index.
[0054] When using the alkali metal salts adopted in the present
invention, basic compounds of sodium hydroxide and potassium
hydroxide used for adjusting the pH are also included when the
various types of aqueous solutions of metal salt are added in
process B. These alkali metal hydroxides can also be used in a
mixed system. The outermost layer is preferably sintered layer, not
only to reduce porosity and increase the refractive index, but also
to increase the smoothness of the outermost layer surface and, as a
result, to increase the brilliance.
(4) Process C: filtering, separating, washing, drying and if
desired calcining the suspension that has passed through process B
or D
[0055] This process is for filtering, separating, washing, drying
and calcining the solid parts in the suspension wherein metal
hydrates for calcining have been deposited.
[0056] In this process, the iridescent pigment according to the
present invention can be obtained by filtering, separating,
washing, drying and calcining the suspension that has passed
through process B or D. The drying is performed in order to remove
free water, while calcination is used to change as many of the
metal hydrates of the coated layer as possible into metal oxides.
Further, the sintering can effectively take place because of the
hydrate layer of the sintering aid added in process D.
[0057] The calcination is performed at a temperature within the
limits corresponding to the heat resistance of the thin
platelet-like substrate used. For example, when using mica,
calcination is performed at a temperature in the vicinity of
800.degree. C.; while in the case of metal and other flakes, which
have a low heat resistance, the temperature is suitably selected
within the limits corresponding to the material in question.
[0058] In this way, the iridescent pigment obtained according to
the present invention is characterized in that the pore amount
(ml/m.sup.2) is 0.006 ml/m.sup.2 or less and has a specific surface
area (BET) of 10 m.sup.2/g or less. Therefore, the coated metal
oxide particles are small and the surface of the coated layer is
smooth and uniform. According to observation through a scanning
electron microscope (SEM), the diameter of the metal oxide
particles is characterized in that it is 50 nm or less. In the
present specification, the "pore amount" is a value obtained by
dividing the total pore volume (ml/g) measured with an Autosorb 6
(manufactured by Yuasa-ionics) by the specific surface area (BET)
(m.sup.2/g) of the thin platelet-like substrates.
[0059] Moreover, porosity (%) P is calculated from the total pore
volume {porosity=100.times.total pore volume/(total pore
volume+(amount of coated metal oxide (wt. %)/density (g/ml)))}; and
the refractive index can be calculated according to the formula
{n.sub.p.sup.2=(n.sup.2 1) (1-P/100)+1, wherein n.sub.p indicates
the calculated refractive index, n indicates the true refractive
index and P indicates the porosity (%)} of the relationship between
the refractive index and the porosity according to Yoldus (B. E.
Yoldus, Appl. Opt., 19, p. 1425 (1980) and Kawahara (The Chemical
Society of Japan, Japan Scientific Societies Press, The Chemical
Review "Surface Reforming", No. 44, 1984, pp. 139-146). When
calculating the refractive index of the iridescent pigment obtained
by the present invention according to this formula, a high value of
2.33 or more is obtained by approximating all constituting
components of the coated metal oxides with the principal component
of the coated metal oxides TiO.sub.2 (true density d: 4.27, true
refractive index n: 2.7).
[0060] The iridescent pigment thus obtained can be used in
decoration in various fields, paints, plastics, inks, printing,
cosmetics, paint for security, ink for security, or incorporation
to plastic for security, dopants for laser marking, non-dusting
pigment products, non-dusting pigment granules and other types of
applications.
[0061] Above all, the iridescent pigment obtained according to the
present invention is advantageous in the painting sector, where,
when applied to thin platelet-like substrates with fine particle
diameter, particle feeling does not occur in the painted film and
where, because of the high brilliance and high chroma, particle
feeling in the painting is not desirable, and in sectors in which
the particle size is restricted such as in inks for offset printing
and writing appliances. The pearl-luster pigments obtained
according to the present invention produce a sense of depth and can
be applied to the security sector (printing, plastic sealing) etc.
The iridescent pigment obtained according to the present invention
can also be used for coating onto the surface of commonly known
organic pigments (e.g., those given below), dyes, lake pigments and
inorganic pigments by mechanochemical means in order to produce a
new color material (e.g., JP-A-05-214257). Vivid colors can be
obtained by combining interference colors produced by the
interference effect with the inherent colors resulting from the
absorption by these pigments and dyes.
[0062] By applying various types of additional surface treatments,
the iridescent pigment obtained according to the present invention
can also be used to produce pigments meeting the quality
requirements corresponding to these applications. For example, it
is possible to carry out treatments for light resistance, water
resistance and weather resistance required of paints for outdoor
applications and of paints for the automobile industry, etc. (e.g.,
JP-A-63-130673, JP-A-1-292067, etc.), treatments to impart high
orientation properties (leafing) required e.g. in the painting and
printing sectors (e.g., JP-A-2001-106937, JP-A-2001-164150,
JP-A-2001-220522, etc.), water-borne treatments for water-borne
paints or inks (e.g. JP-A-08-283604, etc.), silicon treatment for
improving dispersibility and hydrogenpolysiloxane treatment for
improving hydrophobic and oleophobic properties for applications in
the cosmetics sector, surface treatments for weld-line prevention
when used as resin (e.g. JP-A-03-100068), and various types of
treatments for improving dispersibility (e.g. JP-A-08-283604).
Use Examples of the Iridescent Pigment Obtained According to the
Present Invention
[0063] Hereinafter, the iridescent pigment obtained according to
the present invention and the use of the various types of treated
pigments mentioned above will be described in detail. The
iridescent pigment obtained according to the present invention can
be used in various applications such as paints, printing inks,
resin compositions, cosmetics, dopants for laser marking,
non-dusting pigment products and non-dusting pigment granules, etc.
It is particularly advantageous in sectors in which the particle
size is restricted, because color properties (chroma and
brilliance) are high with fine particle diameters, and in sectors
in which particle sensitivity is not desired. Although not
particularly mentioned, the iridescent pigments according to the
present invention used in the following examples include also the
products prepared by applying the various types of treatments
mentioned above.
(1) Use for Paints
[0064] Examples of use in paints are organic solvent-type paints,
NAD (non-aqueous dispersion) paints, water-borne paints, emulsion
paints, colloidal paints and powder paints. The iridescent pigment
according to the present invention is advantageous for automobile
paints, etc., where particle sensitivity is not desired, because
coloration (chroma) is high with fine particle diameters. For paint
applications outdoors and in the automobile industry, it is
preferred to use pigments treated for light resistance, water
resistance and weather resistance.
[0065] The iridescent pigment according to the present invention
can be mixed in a proportion of 1 to 100 weight parts for 100
weight parts of the paint resin as solid parts. A proportion of
1-70 wt. % is preferred. A proportion of 1-20 wt. % is particularly
preferable. For improving dispersibility the surface of the
pigments in the present invention can be treated with a silane
coupling agent and a titanium coupling agent. Examples of resin
components for the paints in the present invention are acrylate
resins, alkyd resins, unsaturated polyester resins, amino resins,
melamine resins, polyurethane resins, epoxy resins, polyamide
resins, phenol resins, cellulose resins, vinyl resins, silicone
resins, fluorine resins, etc. These resins may be used alone or in
combination of two or more. For water-borne paint, emulsion-type
resins comprising cross-linking acrylate melamine resin can be
given as example.
[0066] Examples of mixtures and admixtures for paints include
combination pigments, antisagging agent, viscosity adjusting
agents, sedimentation preventers, cross-linking promoters, curing
agents, leveling agents, defoaming agents, plasticizers, antiseptic
agents, antifungal agents, ultraviolet stabilizers, etc. Examples
of combination pigments are titanium dioxide; calcium carbonate;
clay; talc; barium sulfate; white carbon; chromium oxide; zinc
oxide; zinc sulfide; zinc powder; metal powder pigments; metal
flake pigments (such as aluminum flakes, colored aluminum flakes,
stainless steel flakes, titanium flakes, etc.); anti-corrosive
metal flakes (such as base flakes of aluminum flake substrates);
metal oxide coated metal flakes (such as titanium oxide or iron
oxide coated aluminum flakes); iron black; yellow iron oxide; red
iron oxide; chrome yellow; carbon black; molybdate orange; Prussian
Blue; ultramarine blue; cadmium type pigments; fluorescent
pigments; soluble azo dyes; insoluble azo dyes; condensed azo dyes;
phthalocyanine pigments; condensed polycyclic pigments; composite
oxide pigments; graphite; mica (such as muscovite, phlogopite,
synthetic mica, fluorine tetra silicon mica, etc.); metal oxide
coated mica (such as titanium oxide coated mica, titanium dioxide
coated mica, (hydrated) iron oxide coated mica, mica coated with
iron oxides and titanium oxides, mica coated with lower ordered
titanium oxides); metal oxide coated graphite (such as titanium
dioxide coated graphite, etc.), thin platelet-like alumina; metal
oxide coated thin platelet-like alumina (such as titanium dioxide
coated thin platelet-like alumina, iron oxide coated thin
platelet-like alumina, Fe.sub.2O.sub.3 coated thin platelet-like
alumina, Fe.sub.3O.sub.4 coated thin platelet-like alumina,
interference color metal oxide coated thin platelet-like alumina,
etc.); metal flake pigments (such as aluminum flakes, colored
aluminum flakes, stainless steel flakes, titanium flakes, etc.);
anti-corrosive metal flakes (such as base flakes of aluminum flake
substrates); metal oxide coated metal flakes (such as titanium
oxide or iron oxide coated aluminum flakes); MIO; metal oxide
coated MIO; metal oxide coated silica flakes and metal oxide coated
glass flakes called optical effect pigments (effect pigments).
Other examples are photochromic pigments, thermochromic pigments
and holographic pigments called functional pigments etc. By
combining these and other pigments, novel hues and chromatic
properties can be improved. These paints can be applied to wood,
plastic, metal sheet plate, glass, ceramic, paper, film, sheets,
translucent films of reflectors for LCDs, etc. Examples of uses for
paints include automobiles, buildings, marine vessels, electric
household appliances, canned goods, industrial equipment, traffic
signs, plastic, household goods, etc.
[0067] Examples of the structure of the coated paint film include
e.g. a film coated in the order of: base coat layer, middle coat
layer, layer containing the pigments of the present invention and
clear layer; and in the order of: base coat layer, middle coat
layer containing the pigments of the present invention and clear
layer, etc.; however, the structure of the coated film is not
limited thereto.
[0068] Examples of the method for forming the coated paint film are
one-coat/one-bake, two-coat/one-bake, two-coat/two bake,
three-coat/one-bake, three-coat/two-bake, three-coat/three-bake,
etc. Examples of coating methods include electrostatic coating,
spray coating, airless coating, roll coating, dip coating, etc. The
coated paint films thus obtained have high brilliance and high
chroma.
(2) Use for Printing Inks
[0069] The iridescent pigment according to the present invention
can be used as printing ink. Examples of printing inks include
letter Press ink, offset printing ink, intaglio printing ink, ink
for metal plates, radiation curable ink, UV ink, EB ink, flexo ink,
screen ink, offset ink, gravure ink, etc. and water-borne inks
thereof, etc. The iridescent pigment according to the present
invention is particularly advantageous for offset ink where color
properties (chroma, brilliance) are high with fine particle
diameters. And since its color properties are high with fine
particles, it is also advantageous for ink of writing appliances.
The iridescent pigment according to the present invention can be
mixed in a proportion of 1 to 100 weight parts for 100 weight parts
of the solid resins parts in the ink. A proportion of 1-70 wt. % is
preferred. A proportion of 1-20 wt. % is particularly preferable.
Moreover, the surface of the pigments in the present invention can
be treated with silane coupling agents and titanium coupling
agents, etc. Examples of resin components include e.g. maleic rosin
resins, maleic resins, alkyd resins, polyamide resins, phenol
resins, petroleum resins, urethane resins, epoxy resins, acrylate
resins, butyral resins, melamine resins, epoxy resins, vinyl
chloride resins, vinylidene chloride resins, cellulose resins,
vinyl resins, unsaturated polyester resins, cellulose resins, etc.
These resins may be used alone or in combination of two or
more.
[0070] Examples admixed in ink include combination pigments and
additives such as varnishes, reducers, compounders, extra
varnishes, gelling agents, drying promoters, antioxidants,
anti-offsetting agents, lubricants, surface active agents, etc.
Further examples include antisagging agent, viscosity adjusting
agents, sedimentation preventers, cross-linking agents, curing
agents, leveling agents, defoaming agents, plasticizers, antiseptic
agents, antifungal agents, ultraviolet stabilizers, etc.
[0071] Examples of combination pigments are body pigments;
precipitated barium sulfate; precipitated calcium carbonate;
alumina white; magnesium carbonate and white carbon; white pigments
such as titanium oxide, white zinc, etc.; black pigments such as
carbon black; yellow pigments such as chrome yellow, disazo yellow,
Hansa yellow; red pigments such as brilliant carmine 6B, lake red
C, permanent red F5R, Rhodamine Lake, etc.; blue pigments such as
phthalocyanine blue, Victoria Blue Lake, Prussian Blue; orange
pigments such as chrome vermilion, disazo orange; green pigments
such as phthalocyanine green, etc.; violet pigments such as methyl
violet lake, dioxazine violet, etc.; other pigments such as
isoindolinone, benzimidazoline, condensed azo, quinacdrine, etc.;
composite oxide pigments; graphite; mica (such as muscovite,
phlogopite, synthetic mica, fluorine tetra silicon mica, etc.);
metal oxide coated mica (such as titanium oxide coated mica,
titanium dioxide coated mica, (hydrated) iron oxide coated mica,
mica coated with iron oxides and titanium oxides, mica coated with
lower ordered titanium oxides); metal oxide coated graphite (such
as titanium dioxide coated graphite, etc.), thin platelet-like
alumina; metal oxide coated thin platelet-like alumina (such as
titanium dioxide coated thin platelet-like alumina, iron oxide
coated thin platelet-like alumina, Fe.sub.2O.sub.3 coated thin
platelet-like alumina, Fe.sub.3O.sub.4 coated thin platelet-like
alumina, interference color metal oxide coated thin platelet-like
alumina, etc.); metal flake pigments (such as aluminum flakes,
colored aluminum flakes, stainless steel flakes, titanium flakes,
etc.); anti-corrosive metal flakes (such as base flakes of aluminum
flake substrates); metal oxide coated metal flakes (such as
titanium oxide or iron oxide coated aluminum flakes); MIO; metal
oxide coated MIO; metal oxide coated silica flakes and metal oxide
coated glass flakes called optical effect pigments (effect
pigments). Other examples are photochromic pigments, thermochromic
pigments and holographic pigments called functional pigments etc.
These inks can be printed on wood, plastic, metal sheet plate,
glass, ceramic, paper, corrugated cardboard, film, sheets, canned
goods, translucent films of reflectors for LCDs, etc. Novel hues
and functions can be uncovered as a result of combining these
pigments etc. with the pigments according to the present invention.
In particular, the iridescent pigment according to the present
invention is advantageously used for preventing the counterfeiting
of securities, tickets, travel coupons and passenger tickets,
etc.
[0072] Moreover, when the iridescent pigments according to the
present invention are used in printing inks, it is preferred to
perform a high orientation treatment (mentioned above) especially
on interference pigments having metallic luster obtained according
to the present invention. Pigments that have been subject to such a
surface treatment can be mixed with various types of printing inks
and used for offset printing, gravure printing, screen printing,
ultraviolet cure printing, relief and intaglio printing. According
to the present invention, the use of iridescent pigments that have
been subject to high orientation treatment as inks makes it
possible to improve especially the coloration of interference
colors on the printing surface and is preferred for preventing
counterfeiting in printing.
[0073] The writing appliance industry is an example for the use as
ink of the pigments according to the present invention.
Particularly, it can be used in felt pens, etc. in which the
particle size is restricted. Printed matter obtained in this way
has high brilliance and high chroma.
(3) Use for Plastics
[0074] The iridescent pigments according to the present invention,
when incorporated in plastics, can be mixed with the resin, either
directly or after it has been formed into pellets, before being
formed into various types of molded products by means of extrusion
molding, calender molding, blow molding, etc. As to the resin
component, polyolefin-based thermoplastic resins as well as
epoxy-based, polyester-based and polyamide (nylon)-based
thermoplastic resins can be used. A small amount of pigments can be
sufficient to effectively produce the color effects of the
iridescent pigments of the present invention, e.g., when forming a
multiple layer plastic bottle, the external appearance of the
bottle can be made to appear effectively by incorporating the
pigments in the resin of the outer layer. Especially pigments
obtained according to the present invention on which an additional
orientation treatment has been performed (as described above) are
preferred in that they have good coloring properties. Naturally, it
is also possible to use a weld-line prevention surface treated
(such as encapsulation etc.) on the iridescent pigments according
to the present invention.
[0075] The iridescent pigments according to the present invention
can also be used in combination with other pigments. Examples of
pigments that can be used in combination with the pigments of the
present invention include titanium dioxide; calcium carbonate;
clay; talc; barium sulfate; white carbon; chromium oxide; zinc
oxide; zinc sulfide; zinc powder; metal powder pigments; iron
black; yellow iron oxide; red iron oxide; chrome yellow; carbon
black; molybdate orange; Prussian Blue; ultramarine blue; cadmium
type pigments; fluorescent pigments; soluble azo dyes; insoluble
azo dyes; condensed azo dyes; phthalocyanine pigments; condensed
polycyclic pigments; composite oxide pigments; graphite; metal
powder pigments; mica (such as, muscovite, phlogopite, synthetic
mica, fluorine tetra silicon mica, etc.), metal oxide coated mica
(such as titanium oxide coated mica, titanium dioxide coated mica,
(hydrated) iron oxide coated mica, mica coated with iron oxides and
titanium oxides, mica coated with lower ordered titanium oxides);
metal oxide coated graphite (such as titanium dioxide coated
graphite, etc.), thin platelet-like alumina; metal oxide coated
thin platelet-like alumina (such as titanium dioxide coated thin
platelet-like alumina, iron oxide coated thin platelet-like
alumina, Fe.sub.2O.sub.3 coated thin platelet-like alumina,
Fe.sub.3O.sub.4 coated thin platelet-like alumina, interference
color metal oxide coated thin platelet-like alumina, etc.); metal
flake pigments (such as aluminum flakes, colored aluminum flakes,
stainless steel flakes, titanium flakes, etc.); anti-corrosive
metal flakes (such as base flakes of aluminum flake substrates);
metal oxide coated metal flakes (such as titanium oxide or iron
oxide coated aluminum flakes); MIO; metal oxide coated MIO; metal
oxide coated silica flakes and metal oxide coated glass flakes
called optical effect pigments (effect pigments). Other examples
are photochromic pigments, thermochromic pigments, conductive
pigments and holographic pigments called functional pigments, etc.
The resin products obtained in this way have high brilliance and
high chroma.
(4) Use for Cosmetics
[0076] The iridescent pigments according to the present invention
can be used in make-up, hair care products, cosmetic packs, etc.
The pigments can be used for example in gel, lipstick, foundation
(including emulsion, liquid, oil-type emulsions, etc.), cheek
rouge, mascara, nail enamel, eyebrow pencil, eye shadow, eye liner,
hair products, etc. The iridescent pigments according to the
present invention can be used in a proportion of, for example, 1 to
50 wt. % for foundations, 1 to 80 wt. % for eye shadow, 1 to 40 wt.
% for lipstick and 0.1 to 20 wt. % for nail enamel and up to 100
wt. % for press powders.
[0077] Examples of other mixed components will be given below.
Examples of pigments that can be used in combination with the
pigments of the present invention include titanium dioxide; calcium
carbonate; clay; talc; barium sulfate; white carbon; chromium
oxide; zinc oxide; zinc sulfide; zinc powder; metal powder
pigments; iron black; yellow iron oxide; red iron oxide; chrome
yellow; carbon black; molybdate orange; Prussian Blue; ultramarine
blue; cadmium type pigments; fluorescent pigments; soluble azo
dyes; insoluble azo dyes; condensed azo dyes; phthalocyanine
pigments; condensed polycyclic pigments; composite oxide pigments;
graphite; metal powder pigments; mica (such as, muscovite,
phlogopite, synthetic mica, fluorine tetra silicon mica, etc.),
metal oxide coated mica (such as titanium oxide coated mica,
titanium dioxide coated mica, (hydrated) iron oxide coated mica,
mica coated with iron oxides and titanium oxides, mica coated with
lower ordered titanium oxides); metal oxide coated graphite (such
as titanium dioxide coated graphite, etc.), thin platelet-like
alumina; metal oxide coated thin platelet-like alumina (such as
titanium dioxide coated thin platelet-like alumina, iron oxide
coated thin platelet-like alumina, Fe.sub.2O.sub.3 coated thin
platelet-like alumina, Fe.sub.3O.sub.4 coated thin platelet-like
alumina, interference color metal oxide coated thin platelet-like
alumina, etc.); metal flake pigments (such as aluminum flakes,
colored aluminum flakes, stainless steel flakes, titanium flakes,
etc.); anti-corrosive metal flakes (such as base flakes of aluminum
flake substrates); metal oxide coated metal flakes (such as
titanium oxide or iron oxide coated aluminum flakes); MIO; metal
oxide coated MIO; metal oxide coated silica flakes and metal oxide
coated glass flakes called optical effect pigments (effect
pigments). Other examples are photochromic pigments, thermochromic
pigments and holographic pigments called functional pigments, etc.
Further examples are sericite, magnesium carbonate, silica,
zeolite, hydroxyapatite, chromium oxide, cobalt titanate, glass
beads, nylon beads, silicone beads, etc.
[0078] Examples of organic pigments used as combination pigments
include red nos. 2, 3, 102, 104, 105, 106, 201, 202, 203, 204, 205,
206, 207, 208, 213, 214, 215, 218, 219, 220, 221, 223, 225, 226,
227, 228, 230-1, 230-2, 231, 232, 405; yellow nos. 4, 5, 201,
202-1, 202-2, 203, 204, 205, 401, 402, 403, 404, 405, 406, 407;
green nos. 3, 201, 202, 204, 205, 401, 402; blue nos. 1, 2, 201,
202, 203, 204, 205, 403, 404; orange nos. 201, 203, 204, 205, 206,
207, 401, 402, 403; brown no. 201; violet nos. 201, 401; black no.
401. Examples of natural colors include salol yellow, carmine,
.beta.-carotin, hibiscus color, capsaicin, carminic acid, laccaic
acid, gurcumin, riboflavin, shikonin, etc.
[0079] Further, examples of other components include fats and oils,
waxes, surfactants, oxidation inhibitors, UV absorbers, vitamins,
hormones, squalanes, liquid paraffins, palmitic acids, stearic
acids, bees wax, myristyl myristate and other esters; acetone,
toluene, butyl acetate, acetic ester and other solvents;
antioxidants, antiseptic agents, polyhydric alcohols, perfumes,
etc. Novel hues and functions can be uncovered as a result of
combining these pigments etc. with the pigments according to the
present invention.
[0080] When used in cosmetics, the pigments according to the
present invention can be used for example in compact cakes, cream,
lipstick, etc.; however, they are particularly effective when used
in make-up, wherein colors are particularly important. Naturally,
it is equally possible to use iridescent pigments related to the
present invention on which a surface treatment (mentioned above)
has been performed beforehand. The cosmetic products obtained in
this way have high brilliance and high chroma.
(5) Other Uses
[0081] The iridescent pigments of the present invention can be used
by combining them with color toners for copying machines, etc.
Applications in this field are preferred because they require high
coloration with fine particles.
[0082] They can also be used for dopants for laser marking,
non-dusting pigment products and non-dusting pigment granules.
[0083] Hereinafter, examples according to the present invention
will be given which, however, are not intended to limit the present
invention.
EXAMPLES
Example 1
[0084] 180 g of fine-mica powder of 1 to 15 .mu.m (average particle
diameter: 5.5 .mu.m) were suspended in 1.5 liters of deionized
water. 2 g of polyethylene glycol 400 (PEG 400) was added while
stirring. The suspension was heated to 85.degree. C. while
stirring. An aqueous solution of sodium hydroxides and, 440 ml of
an aqueous solution of SnCl.sub.4 with its concentration of 70 g/l
containing hydrochloric acid were simultaneously added at a rate of
3.2 ml/min, while maintaining the pH at 1.9. Further, an aqueous
solution of sodium hydroxides and, 700 ml of an aqueous solution of
TiCl.sub.4 with its concentration of 403 g/l were simultaneously
added at a rate of 3.4 ml/min, while maintaining the pH at 1.6.
Then, the pH was adjusted to 9.0 by adding sodium hydroxide.
Thereafter, the metal hydrate coated mica was filtered from the
suspension and washed, the filtrate was dried at 105.degree. C. and
calcined at 850.degree. C. and the silver iridescent pigments were
obtained.
[0085] SEM observation confirmed that the diameter of the coated
particles was 50 nm or less.
Example 2
[0086] 120 g of fine-mica powder of 1 to 15 .mu.m (average particle
diameter: 6.4 .mu.m) were suspended in 1.5 liters of deionized
water. 1 g of polyethylene glycol 200 (PEG 200) was added while
stirring. The suspension was heated to 85.degree. C. while
stirring. An aqueous solution of sodium hydroxides and, 100 ml of
an aqueous solution of SnCl.sub.4 with its concentration of 70 g/l
containing hydrochloric acid were simultaneously added at a rate of
2.5 ml/min, while maintaining the pH at 2.0. Further, an aqueous
solution of sodium hydroxides and, 450 ml of an aqueous solution of
TiCl.sub.4 with its concentration of 403 g/l were simultaneously
added at a rate of 2.0 ml/min, while maintaining the pH at 1.6. An
aqueous solution of sodium hydroxides and, 100 ml of an aqueous
solution of SnCl.sub.4 with its concentration of 70 g/l containing
hydrochloric acid were simultaneously added at a rate of 2.5
ml/min, while maintaining the pH at 1.6. Further, an aqueous
solution of sodium hydroxides and, an aqueous solution of
TiCl.sub.4 with its concentration of 420 g/l were simultaneously
added at a rate of 2.7 ml/min, while maintaining the pH at 1.6. The
adding of this aqueous solution of TiCl.sub.4 was stopped at the
end point at which the color turned to silver. Thereafter, 4.0 g of
MgCl.sub.2. 6H.sub.2O and 8 g of CaCl.sub.2. 2H.sub.2O were added.
Then, the pH was adjusted to 9.0 by adding an aqueous solution of
sodium hydroxide. Thereafter, the metal hydrate coated mica was
filtered from the suspension and washed, the filtrate was dried at
105.degree. C. and calcined at 800.degree. C. (850.degree. C.) and
the iridescent pigments were obtained. SEM observation confirmed
that the diameter of the coated particles was 50 nm or less.
Example 3
[0087] 120 g of fine-mica powder of 5 to 25 .mu.m (average particle
diameter: 8.5 .mu.m) were suspended in 1.5 liters of deionized
water. The suspension to which 1 g of polyethylene glycol 200 (PEG
200) and 0.5 g of polyethylene glycol 400 (PEG 400) had been added
while stirring was heated to 85.degree. C. while stirring. An
aqueous solution of sodium hydroxides and, 200 ml of an aqueous
solution of SnCl.sub.4 with its concentration of 70 g/l containing
hydrochloric acid were simultaneously added at a rate of 2.0
ml/min, while maintaining the pH at 2.0. Further, an aqueous
solution of sodium hydroxides and, 350 ml of an aqueous solution of
TiCl.sub.4 with its concentration of 408 g/l were simultaneously
added at a rate of 1.3 ml/min, while maintaining the pH at 1.6.
Then, the pH was adjusted to 9.0 by adding an aqueous solution of
sodium hydroxide. Thereafter, the metal hydrate coated mica was
filtered from the suspension and washed, the filtrate was dried at
105.degree. C. and calcined at 850.degree. C. and the silver
iridescent pigments were obtained. SEM observation confirmed that
the diameter of the coated particles was 50 nm or less.
Example 4
[0088] 120 g of fine-grained mica powder of 5 to 25 .mu.m (average
particle diameter: 8.5 .mu.m) were suspended in 1.5 liters of
deionized water. 1 g of polyethylene glycol 200 (PEG 200) and 0.5 g
of polyethylene glycol 400 (PEG 400) were added while stirring. The
suspension was heated to 85.degree. C. while stirring. A solution
in which 5 g of cerous chloride 7 hydrates were dissolved in 200 ml
of water was dropped into the suspension at a rate of 3 ml/min
while adjusting the pH to 7.0 with a 32% aqueous solution of sodium
hydroxide. A solution in which 4.0 g CaCl.sub.2. 2H.sub.2O and 2.0
g MgCl.sub.2. 6H.sub.2O were dissolved in 100 ml of an aqueous
solution of SnCl.sub.4 with its concentration of 70 g/l containing
hydrochloric acid was added at a rate of 2.5 ml/min while
maintaining the pH at 2.0 by simultaneously using an aqueous
solution of sodium hydroxide. Further, an aqueous solution of
sodium hydroxides and, an aqueous solution of TiCl.sub.4 with its
concentration of 408 g/l were simultaneously added at a rate of 1.3
ml/min, while maintaining the pH at 1.6. Then, a solution in which
4 g of calcium chloride 2 hydrates and 2 g of magnesium chloride 6
hydrates were dissolved in 100 ml of an aqueous solution of
SnCl.sub.4 with its concentration of 70 g/l containing hydrochloric
acid was added at a rate of 2.0 ml/min while maintaining the pH at
2.0 by simultaneously using an aqueous solution of sodium
hydroxide. Further, an aqueous solution of sodium hydroxides and,
an aqueous solution of TiCl.sub.4 with its concentration of 408 g/l
were simultaneously added at a rate of 1.2 ml/min, while
maintaining the pH at 1.6. The adding of this aqueous solution of
TiCl.sub.4 was stopped at the end point at which the color turned
to silver. Then, the pH was adjusted to 9.0 by adding an aqueous
solution of sodium hydroxide. Thereafter, the metal hydrate coated
mica was filtered from the suspension and washed, the filtrate was
dried at 105.degree. C. and calcined at 870.degree. C. and the
iridescent pigments were obtained. SEM observation confirmed that
the diameter of the coated particles was 50 nm or less.
Example 5
[0089] 122 g of fine-mica powder of 1 to 15 .mu.m (average particle
diameter: 6.4 .mu.m) were suspended in 1.75 liters of deionized
water. 1 g of polyethylene glycol 200 (PEG 200) was added while
stirring. The suspension was heated to 85.degree. C. while
stirring. An aqueous solution of sodium hydroxides and, 200 ml of
an aqueous solution of SnCl.sub.4 with its concentration of 70 g/l
containing hydrochloric acid were simultaneously added at a rate of
2.8 ml/min, while maintaining the pH at 2.0. Further, an aqueous
solution of sodium hydroxides and, 650 ml of an aqueous solution of
TiCl.sub.4 with its concentration of 388 g/l were simultaneously
added at a rate of 2.7 ml/min, while maintaining the pH at 1.6. An
aqueous solution of sodium hydroxides and, 200 ml of an aqueous
solution of SnCl.sub.4 with its concentration of 70 g/l containing
hydrochloric acid were simultaneously added at a rate of 2.8
ml/min, while maintaining the pH at 1.6. Further, an aqueous
solution of sodium hydroxides and, an aqueous solution of
TiCl.sub.4 with its concentration of 420 g/l were simultaneously
added at a rate of 2.5 ml/min, while maintaining the pH at 1.6. The
adding of this aqueous solution of TiCl.sub.4 was stopped at the
point at which the color turned to a blue interference color.
Thereafter, 2.5 g of MgCl.sub.2. 6H.sub.2O and 5 g of CaCl.sub.2.
2H.sub.2O were added. Then, the pH was adjusted to 9.0 by an
aqueous solution of adding sodium hydroxide. Thereafter, the metal
hydrate coated mica was filtered from the suspension and washed,
the filtrate was dried at 105.degree. C. and calcined at
800.degree. C. and the iridescent pigments were obtained. SEM
observation confirmed that the diameter of the coated particles was
50 nm or less.
Example 6
[0090] Fine mica (17.5 kg) particle having 115 .mu.m in the
particle size was suspended in 250 l of deionized water. 120 g of
PEG#200 was added to the suspension under stirring. The suspension
was heated up to 85.degree. C. with stirring, 37.6 l of aqueous
solution of SnCl.sub.4 (53 g/l) containing HCl solution was added
at the rate of 527 ml/min to the suspension in controlling the pH
1.6 by simultaneous addition of aqueous NaOH solution.
[0091] 35 l of aqueous solution of TiCl.sub.4 (420 g/l) was added
at the rate of 356 ml/min to the suspension in controlling the pH
1.6 by simultaneous addition of aqueous NaOH solution. Then 37.6 l
of aqueous solution of SnCl.sub.4 (53 g/l) containing HCl solution
was added at the rate of 527 ml/min to the suspension in
controlling the pH 1.6 by simultaneous addition of aqueous NaOH
solution. After adding the aqueous solution of SnCl.sub.4 the
aqueous solution of TiCl.sub.4 (420 g/l) was added at the rate of
356 ml/min to the suspension in controlling the pH 1.6 by
simultaneous addition of aqueous NaOH solution.
[0092] After reaching to end point of Blue.
[0093] 10 l of aqueous of 0.35 kg of MgCl.sub.2.6H.sub.2O and 0.71
kg of CaCl.sub.2.2H.sub.4O was added to the suspension. The pH
value of the suspension was controlled pH 9.0 by adding aqueous
NaOH solution. The suspension containing mica coated with metal
hydroxide was filtrated and washed by deionized water. The filter
cake was dried at 105.degree. C. and the dried product was
calcinated at 770.degree. C.
[0094] After the calcinated product was sieved by 63 .mu.m sieve,
the coating paper for measuring of L.a.b. and Chrome of the
produced pigment was prepared as follows:
[0095] 0.5 g of pigment with interference blue was added into 9.5 g
of lacquer of nitrocellulose and it is spread on a testing paper of
hiding power by barcoder No. 20. (L.a.b. values on black ground
were measured by Minolta color analyzer model CR-300).
[0096] The chroma of interference Blue pigments was 37.8
TABLE-US-00001 TABLE 1 Specific Hiding Total Average surface Pore
power pore particle area amount Y value ratio volume Sample dia.
(.mu.m) (m.sup.2/g) (ml/m.sup.2) Porosity (%) (.times.10.sup.3) (%)
(ml/g) Example 6 8.3 8.2 0.0024 10.7 9.6 0.12 0.0197
[0097] TABLE-US-00002 TABLE 2 Average particle L a b C (Chroma) Hue
angle Sample dia. (.mu.m) value value value {square root over
((a.sup.2 + b.sup.2))} (Tan.sup.-1(b/a)) Example 6 8.3 36.2 11.1
-35.3 37.8 287.0
Comparative Example 1
[0098] Pigments were prepared under the same conditions as in
Example 1, except that polyethylene glycol 400 (PEG 400) was not
added to the suspension of fine-mica powder.
(A) Measurement of the Average Particle Diameter
[0099] The average particle diameter was measured with a Master
Sizer 2000.
(B) Measurement of the Specific Surface Area and the Total Pore
Volume
[0100] The specific surface area was measured with an Autosorb 6
(manufactured by Yuasa-ionics) according to the B.E.T method.
[0101] The pore amount is a value obtained by dividing the total
pore volume by the specific surface area of the thin platelet-like
substrates (refer to paragraph (0034)). (C) Porosity is calculated
according to the following formula from the total pore volume, the
true density of titanium oxide (4.27) and the weight percentage of
that coated metal oxide. Porosity .times. .times. ( % ) = total
.times. .times. pore .times. .times. volume .times. .times. ( ml
.times. / .times. g ) coated .times. .times. metal .times. .times.
oxide .times. .times. weight .times. .times. ( % ) 0.01 coated
.times. .times. metal .times. .times. oxide .times. .times. density
.times. .times. ( g .times. / .times. ml ) + total .times. .times.
pore .times. .times. volume .times. .times. ( ml .times. / .times.
g ) 100 ( Formula .times. .times. 2 ) ##EQU1## (D) Measurement of
Brilliance
[0102] Brilliance of pigments was compared by measuring the
reflectance (value Y; this value increases with increasing
brilliance) of the pigments. The measurements were conducted as
follows. Namely, the pigments were dispersed by using a
nitrocellulose lacquer so as to achieve a concentration of 3 wt. %,
draw-down cards were prepared and the value Y was measured at an
incident angle of 45.degree. and a measurement angle of 45.degree.
by using a goniospectrophotometer GCMS-3 (manufactured by Murakami
Color Research Laboratory).
(E) Hiding Power Ratio
[0103] The hiding power ratio is expressed as a percentage value
obtained by dividing the value Y on a black background by the value
Y on a white background, both measured with a Minolta color meter
(CR 300).
[0104] The results are shown in Table 3. TABLE-US-00003 TABLE 3
Specific Hiding Total Average surface Pore power pore particle area
amount Y value ratio volume Sample dia. (.mu.m) (m.sup.2/g)
(ml/m.sup.2) Porosity (%) (.times.10.sup.3) (%) (ml/g) Example 1
6.0 9.4 0.0058 28.5 8.2 0.33 0.038 Example 2 7.4 4.7 0.0028 15.7
9.1 0.36 0.013 Example 3 10.3 9.5 0.0030 28.5 8.5 0.38 0.030
Example 4 10.5 3.1 0.0020 11.9 10.5 0.43 0.042 Comp. 6.0 12.6
0.0061 30.5 7.2 0.34 0.042 Example 1 Iriodin .RTM. 111 6.3 12.4
0.0065 32.0 6.3 0.34 0.047 Iriodin .RTM. 121 10.9 9.0 0.0083 32.0
7.8 0.26 0.039 Iriodin .RTM. 123 11.0 10.0 0.0074 30.0 8.3 0.29
0.039
[0105] Iriodin.RTM. 111: Silver pearl-luster pigment with a single
layer coat of rutile-type TiO.sub.2 of an average particle diameter
of 6.3 .mu.m manufactured by Merck KGaA, Darmstadt.
[0106] Iriodin.RTM. 121: Silver pearl-luster pigment with a single
layer coat of rutile-type TiO.sub.2 of an average particle diameter
of 10.9 .mu.m manufactured by Merck KGaA, Darmstadt.
[0107] Iriodin.RTM. 123: Silver pearl-luster pigment with a single
layer coat of rutile-type TiO.sub.2 of an average particle diameter
of 11.0 .mu.m manufactured by Merck KGaA, Darmstadt.
[0108] Compared to conventional pigments, the pigments obtained
according to the present invention had a high Y value (a high Y
value shows high brilliance) even with fine particle diameters (in
particular Examples 1 and 2) and a high hiding power ratio. The
fact that the hiding power ratio was high also confirms that the
brilliance was also high.
[0109] A comparison of the silver color confirmed that, compared to
the conventional Iriodin.RTM. pigments with an equivalent level of
average particle diameter, the pigments obtained in Examples 1 to 4
had all higher Y values and higher brilliance.
(F) Measurement of Chroma
[0110] The chroma of the pigments of the present invention and
commercially available pigments was measured as follows.
[0111] The pigments were dispersed in nitrocellulose lacquer so as
to achieve a concentration of 5 wt. %, draw-down cards were
prepared and the chroma was measured by using a Minolta color meter
(CR 300).
[0112] The results are shown in Table 4. TABLE-US-00004 TABLE 4
Average particle C (Chroma) Hue angle Sample dia. (.mu.m) L value a
value b value {square root over ((a.sup.2 + b.sup.2))}
(Tan.sup.-1(b/a)) Example 5 8.0 40.1 6.5 -36.4 37.0 280.0 Micro
Blue 7.9 36.4 8.0 -28.6 29.7 285.5 Iriodin .RTM. 221 10.8 38.9 3.8
-29.5 29.7 277.3
[0113] Micro Blue Pearl-luster pigments having a blue interference
color with a single layer coat of TiO.sub.2 of an average particle
diameter of 7.9 manufactured by Engelhard.
[0114] Iriodin.RTM. 221: Pearl-luster pigment having a blue
interference color with a single layer coat of TiO.sub.2 of an
average particle diameter of 11.4 .mu.m manufactured by Merck KGaA,
Darmstadt.
[0115] From the results of Table 4 it can be observed that,
compared to conventional pigments whose hues are in the blue range,
the pigments of the present invention (Example 5) comprising a 2
layer structure of tin oxide and titanium oxide respectively had a
higher chroma.
EXEMPLARY FORMULATIONS
[0116] Hereinafter, specific examples of the use of pigments will
be given.
Use Example 1
[0117] Paint based on pearl-luster pigments
[0118] (Composition A) TABLE-US-00005 (Composition A) Acrydic
47-712 70 weight parts Super Beckamine G821-60 30 weight parts
(Composition B) Iridescent pigment according to the 10 weight parts
present invention Pearl-luster pigment 10 weight parts (Composition
C) Ethyl acetate 50 weight parts Toluene 30 weight parts n-butanol
10 weight parts Solvesso #150 40 weight parts
[0119] 100 weight parts of Composition A were mixed with 20 weight
parts of Composition B, the resulting mixture was diluted to obtain
a viscosity (12 to 15 seconds with Ford Cup #4) suitable for
spray-coating with Composition C, whereupon a basecoat was formed
by spray coating.
[0120] Clear Paint: TABLE-US-00006 Acrydic 44-179 14 weight parts
Super Beckamine L117-60 6 weight parts Toluene 4 weight parts
Methyl isobutyl ketone (MIBK) 4 weight parts Butyl cellosolve 3
weight parts
[0121] This composition was coated on the above pearl-luster
coating, dried at 40.degree. C. for 30 minutes, air-dried at room
temperature and baked at 130.degree. C. for 30 minutes. The coated
film obtained had high brilliance and high chroma.
Use Example 2
Use Example for Plastic
[0122] TABLE-US-00007 High density polyethylene (pellets) 100
weight parts Iridescent pigment according to the 1 weight part
present invention Magnesium stearate 0.1 weight parts Zinc stearate
0.1 weight parts
[0123] These components were dry-blended and formed by injection
molding. These moldings had high brilliance and high chroma.
Use Example 3
Use Example for Ink
[0124] TABLE-US-00008 CCST medium (nitrocellulose resin) 10 weight
parts Iridescent pigment according to the 8 weight parts present
invention
[0125] The solvent NC 102 was added to the ink composition blended
from the above components, and ink with a viscosity of 20 seconds
was prepared with Zahn Cup No. 3. Prints obtained with this ink had
high brilliance and high chroma.
Use Example 4
Use Example for Cosmetics
[0126] (1) Use Example for Compact Powder: TABLE-US-00009 Talc 50
weight parts Iridescent pigment according to the 25 weight parts
present invention Color pigments 5 weight parts Isopropyl myristate
a suitable amount Magnesium stearate 2 weight parts
[0127] (2) Use Example for a Foundation: TABLE-US-00010 Talc 38
weight parts Iridescent pigment according to the 25 weight parts
present invention Mica (8 .mu.m) 10 weight parts Magnesium stearate
3 weight parts Nylon powder 12 8 weight parts Yellow iron oxide 1.9
weight parts Red iron oxide 0.8 weight parts Titanium oxide 1.0
weight part Mineral oil a suitable amount (caprylic acid, capric
acid) triglyceride 3.3 weight parts Butylparaben 0.1 weight
parts
[0128] The cosmetics obtained had high brilliance and high
chroma.
EFFECT OF THE INVENTION
[0129] The iridescent pigments according to the present invention
have higher brilliance and higher chroma than conventional
iridescent pigments, which effect is particularly confirmed in case
of fine particle diameter. The iridescent pigments according to the
present invention can be used for various types of applications
such as painting, printing, ink for writing appliances, plastic
sealing, cosmetics, etc.; among these applications their use is
particularly advantageous in areas where high brilliance and high
chroma are appreciated and a high designer value is required.
Moreover, compared to conventional iridescent pigments, the
iridescent pigments according to the present invention have high
brilliance and high chroma even as iridescent pigments with fine
particle diameter and can be used in sectors where the use is
restricted due to particle diameter, for example in the painting
sector where particle feeling is not desirable, and in sectors in
which the particle size is restricted such as in inks for offset
printing and writing appliances etc.
* * * * *