U.S. patent application number 11/922061 was filed with the patent office on 2009-12-17 for interference pigments on the basis of glass flakes.
Invention is credited to Patrice Bujard.
Application Number | 20090311209 11/922061 |
Document ID | / |
Family ID | 37454256 |
Filed Date | 2009-12-17 |
United States Patent
Application |
20090311209 |
Kind Code |
A1 |
Bujard; Patrice |
December 17, 2009 |
Interference Pigments on the Basis of Glass Flakes
Abstract
The present invention relates to pigments, comprising a
plate-like substrate of glass having an average thickness of <1
.mu.m, especially of from 20 nm to 400 nm, and (a) a dielectric
material, especially a metal oxide, having a high index of
refraction; or (a) a metal layer, especially a thin
semi-transparent metal layer; a process for their production and
their use in paints, ink-jet printing, for dyeing textiles, for
pigmenting coatings (paints), printing inks, plastics, cosmetics,
glazes for ceramics and glass.
Inventors: |
Bujard; Patrice; (Courtepin,
CH) |
Correspondence
Address: |
JoAnn Villamizar;Ciba Corporation/Patent Department
540 White Plains Road, P.O. Box 2005
Tarrytown
NY
10591
US
|
Family ID: |
37454256 |
Appl. No.: |
11/922061 |
Filed: |
June 12, 2006 |
PCT Filed: |
June 12, 2006 |
PCT NO: |
PCT/EP2006/063077 |
371 Date: |
December 12, 2007 |
Current U.S.
Class: |
424/63 ;
106/31.65; 106/441; 106/489; 501/134; 501/53; 524/431 |
Current CPC
Class: |
C09C 1/0024 20130101;
C09C 2200/1025 20130101; C09D 11/037 20130101; A61K 8/0262
20130101; A61K 8/25 20130101; C09C 2200/102 20130101; D06P 1/44
20130101; C01P 2006/12 20130101; A61K 2800/412 20130101; A61K
2800/436 20130101; C01P 2004/20 20130101; C09C 1/0021 20130101;
C09C 2200/301 20130101; C09C 2220/106 20130101; C01P 2004/61
20130101; C09D 7/41 20180101; C09C 1/0015 20130101; C09D 11/40
20130101; A61Q 1/02 20130101; A61K 2800/651 20130101; A61K 2800/621
20130101; C09D 5/36 20130101 |
Class at
Publication: |
424/63 ; 106/441;
106/489; 106/31.65; 501/53; 501/134; 524/431 |
International
Class: |
C04B 14/04 20060101
C04B014/04; C09C 1/36 20060101 C09C001/36; C09D 11/02 20060101
C09D011/02; A61K 8/25 20060101 A61K008/25; C03C 3/04 20060101
C03C003/04; C08K 3/22 20060101 C08K003/22; C04B 35/14 20060101
C04B035/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 22, 2005 |
EP |
05105527.5 |
Claims
1. A pigment, comprising a plate-like substrate of glass having an
average thickness of <1 .mu.m, and (a) a dielectric material,
having a high index of refraction; or (a) a thin semi-transparent
metal layer.
2. A pigment according to claim 1, wherein the glass substrate
consists of ECR glass.
3. The pigment according to claim 1, wherein the pigment comprises
in addition (b) a metal oxide of low refractive index, wherein the
difference of the refractive indices is at least 0.1.
4. The pigment according to claim 3, wherein the metal oxide of
high refractive index is TiO.sub.2, ZrO.sub.2, Fe.sub.2O.sub.3,
Fe.sub.3O.sub.4, Cr.sub.2O.sub.3, ZnO or a mixture of these oxides
or an iron titanate, an iron oxide hydrate, a titanium suboxide or
a mixture and/or mixed phase of these compounds.
5. The pigment according to claim 3, wherein the metal oxide of low
index of refraction is SiO.sub.2, Al.sub.2O.sub.3, AlOOH,
B.sub.2O.sub.3, or a mixture thereof, wherein alkali or earth
alkali metal oxides can be contained as additional component.
6. The pigment according to claim 1, wherein the glass core has an
average thickness of from 20 to 220 nm.
7. The pigment according to claim 1, comprising a mixed layer of
Al.sub.2O.sub.3/TiO.sub.2, or MgO/TiO.sub.2, or a dielectric
layer/a metal layer/a dielectric layer.
8. The pigment according to claim 1, wherein the glass flakes have
a homogenous coating of a metal oxide of high refractive index, and
a large Gaussian thickness distribution of the glass flakes.
9. A process for producing the interference pigment according to
claim 1, by coating glass flakes with one or more metal oxides in a
wet process by hydrolysis of the corresponding water-soluble metal
compounds, by separating, drying and optionally calcinating the
pigment thus obtained, or by suspending glass flakes in an aqueous
and/or organic solvent containing medium in the presence of a metal
compound and depositing the metal compound onto glass flakes by
addition of a reducing agent.
10. (canceled)
11. Paints, printing inks, plastics, cosmetics, ceramics and glass,
which are pigmented with a pigment according to claim 1.
12. A pigment, according to claim 1 comprising a plate-like
substrate of glass having an average thickness of from 20 nm to 400
nm, and (a) a metal oxide, having a high index of refraction; or
(a) a thin semi-transparent metal layer.
13. A pigment according to claim 12, wherein the glass substrate
consists of ECR glass.
14. The pigment according to claim 2, wherein the pigment comprises
in addition (b) a metal oxide of low refractive index, wherein the
difference of the refractive indices is at least 0.1.
15. The pigment according to claim 14, wherein the metal oxide of
high refractive index is TiO.sub.2, ZrO.sub.2, Fe.sub.2O.sub.3,
Fe.sub.3O.sub.4, Cr.sub.2O.sub.3, ZnO or a mixture of these oxides
or an iron titanate, an iron oxide hydrate, a titanium suboxide or
a mixture and/or mixed phase of these compounds.
16. The pigment according to claim 4, wherein the metal oxide of
low index of refraction is SiO.sub.2, Al.sub.2O.sub.3, AlOOH,
B.sub.2O.sub.3, or a mixture thereof, wherein alkali or earth
alkali metal oxides can be contained as additional component.
17. The pigment according to claim 1, wherein the glass core has an
average thickness of from 50 to 220 nm.
18. The pigment according to claim 2, comprising a mixed layer of
Al.sub.2O.sub.3/TiO.sub.2, or MgO/TiO.sub.2, or a dielectric
layer/a metal layer/a dielectric layer.
19. The pigment according to claim 2, wherein the glass flakes have
a homogenous coating of a metal oxide of high refractive index, and
a large Gaussian thickness distribution of the glass flakes.
20. The pigment according to claim 19 wherein the metal oxide of
high refractive index is TiO.sub.2.
Description
[0001] The present invention relates to (interference) pigments
having a core of glass, comprising a metal oxide having a high
index of refraction or a (thin semitransparent) metal layer, a
method of producing the (interference) pigments and their use in
paints, ink-jet printing, for dyeing textiles, for pigmenting
coatings, printing inks, plastics, cosmetics, glazes for ceramics
and glass.
[0002] Interference pigments having a core consisting of a
transparent carrier material, such as, for example, SiO.sub.2, or
glass, are known. Reference is made, for example, to Gerhard Pfaff
and Peter Reynders, Chem. Rev. 99 (1999) 1963-1981.
[0003] WO98/53011 discloses multi-coated interference pigments
consisting of a transparent carrier material which is coated with
alternating metal oxide layers with a high and low refractive
index, wherein the difference between the respective refractive
indexes is 0.1. The metal oxide layers are obtained in a wet
process by hydrolysis of the corresponding water-soluble metal
compounds, by separating, drying and optionally calcinating the
pigment thus obtained.
[0004] The SiO.sub.2 flakes are produced, for example, by a process
described in WO93/08237, wherein a sodium water glass solution is
applied as a thin film on an endless band, solidified and dried.
WO93/08237 also describes the coating of the SiO.sub.2 flakes with
a metal oxide having a high index of refraction or a thin
semitransparent metal layer.
[0005] WO01/57287 describes a process comprising the production of
a substrate material, for example, silicon oxide, by physical vapor
deposition and the wet chemical coating of the obtained flakes
with, for example, TiO.sub.2.
[0006] EP-A-803549 discloses coloured pigments containing (a) a
core consisting of an essentially transparent or metallic
reflecting material, and (b) at least a coating consisting
essentially of one or more silicone oxides, the molar ratio of
oxygen to a silicon being 0.25 to 0.95;
[0007] U.S. Pat. No. 3,331,699 discloses that glass flakes may be
coated with a translucent layer of particles of a metal oxide
having a high index of refraction, such as titanium dioxide,
provided there is first deposited on the glass flakes a nucleating
substance which is insoluble in the acidic solution from which the
translucent layer of metal oxide is deposited.
[0008] WO97/46624 relates to pearlescent pigments comprising flakes
of C glass having a first coating comprising iron oxide or rutile
titanium dioxide thereon.
[0009] WO02/090448 is directed to effect pigments based on glass
flakes with a thickness of <1.0 .mu.m. The glass flakes are
coated with one or more layers with a high and/or low refractive
index and are characterized by a softening point of >800.degree.
C.
[0010] It is the object of the present invention to provide
interference pigments, having high color strength and/or color
purity.
[0011] Said object has been solved by pigments, comprising a
plate-like substrate of glass having an average thickness of
.about.1 .mu.m, especially of from 20 nm to 400 nm, and
(a) a dielectric material, especially a metal oxide, having a high
index of refraction; or (a) a metal layer, especially a thin
semitransparent metal layer.
[0012] The pigment particles generally have a length of from 2
.mu.m to 5 mm, a width of from 2 .mu.m to 2 mm, and an average
thickness of <4 .mu.m, and a ratio of length to thickness of at
least 5:1, and contain a core of glass, having two substantially
parallel faces, the distance between which is the shortest axis of
the core. The glass core is either coated with a dielectric
material, especially a metal oxide, having a high index of
refraction, or a metal layer, especially a thin semi-transparent
metal layer. Said layers can be coated with additional layers.
[0013] According to the present invention the term "aluminum"
comprises aluminum and alloys of aluminum. Alloys of aluminum are,
for example described in G. Wassermann in Ullmanns Enzyklopadie der
Industriellen Chemie, 4. Auflage, Verlag Chemie, Weinheim, Band 7,
S. 281 to 292. Especially suitable are the corrosion stable
aluminum alloys described on page 10 to 12 of WO00/12634, which
comprise besides of aluminum silicon, magnesium, manganese, copper,
zinc, nickel, vanadium, lead, antimony, tin, cadmium, bismuth,
titanium, chromium and/or iron in amounts of less than 20% by
weight, preferably less than 10% by weight.
[0014] Suitable metals for the (semi-transparent) metal layer are,
for example, Cr, Ti, Mo, W, Al, Cu, Ag, Au, or Ni. The
semi-transparent metal layer has typically a thickness of between 5
and 25 nm, especially between 5 and 15 nm.
[0015] The metal layer can be obtained by wet chemical coating or
by chemical vapor deposition, for example, gas phase deposition of
metal carbonyls. The substrate is suspended in an aqueous and/or
organic solvent containing medium in the presence of a metal
compound and is deposited onto the substrate by addition of a
reducing agent. The metal compound is, for example, silver nitrate
or nickel acetyl acetonate (WO03/37993).
[0016] According to U.S. Pat. No. 3,536,520 nickel chloride can be
used as metal compound and hypophosphite can be used as reducing
agent. According to EP-A-353544 the following compounds can be used
as reducing agents for the wet chemical coating: aldehydes
(formaldehyde, acetaldehyde, benzalaldehyde), ketones (acetone),
carbonic acids and salts thereof (tartaric acid, ascorbinic acid),
reductones (isoascorbinic acid, triosereductone, reductine acid),
and reducing sugars (glucose). However, it is also possible to use
reducing alcohols (allyl alcohol), polyols and polyphenols,
sulfites, hydrogensulfites, dithionites, hypophosphites, hydrazine,
boron nitrogen compounds, metal hydrides and complex hydrides of
aluminium and boron. The deposition of the metal layer can
furthermore be carried out with the aid of a CVD method. Methods of
this type are known. Fluidised-bed reactors are preferably employed
for this purpose. EP-A-0741170 describes the deposition of
aluminium layers by reduction of alkylaluminium compounds using
hydrocarbons in a stream of inert gas. The metal layers can
furthermore be deposited by gas-phase decomposition of the
corresponding metal carbonyls in a heatable fluidised-bed reactor,
as described in EP-A-045851. Further details on this method are
given in WO93/12182. A further process for the deposition of thin
metal layers, which can be used in the present case for the
application of the metal layer to the substrate, is the known
method for vapour deposition of metals in a high vacuum. It is
described in detail in Vakuum-Beschichtung [Vacuum Coating],
Volumes 1-5; Editors Frey, Kienel and Lobl, VDI-Verlag, 1995. In
the sputtering process, a gas discharge (plasma) is ignited between
the support and the coating material, which is in the form of
plates (target). The coating material is bombarded with high-energy
ions from the plasma, for example argon ions, and thus removed or
atomised. The atoms or molecules of the atomised coating material
are precipitated on the support and form the desired thin layer.
The sputtering process is described in Vakuum-Beschichtung [Vacuum
Coating], Volumes 1-5; Editors Frey, Kienel and Lobl, VDI-Verlag,
1995. For use in outdoor applications, in particular in the
application in vehicle paints, the pigments can be provided with an
additional weather-stabilising protective layer, the so-called
post-coating, which simultaneously effects optimum adaptation to
the binder system. Post-coatings of this type have been described,
for example, in EP-A-0268918 and EP-A-0632109.
[0017] If pigments with metallic appearance are desired, the
thickness of the metal layer is >25 nm to 100 nm, preferably 30
to 50 nm. If pigments with colored metal effects are desired,
additional layers of colored or colorless metal oxides, metal
nitrides, metal sulfides and/or metals can be deposited. These
layers are transparent or semi-transparent. It is preferred that
layers of high index of refraction and layers of low index of
refraction alternate or that one layer is present, wherein within
the layer the index of refraction is gradually changing. It is
possible for the weathering resistance to be increased by means of
an additional coating, which at the same time causes an optimal
adaption to the binder system (EP-A-268918 and EP-A-632109).
[0018] The metal and/or metal oxide coated glass flakes can be, as
described in US60/689,196 (PCT/EP2006/062758), treated with a
plasma torch. The treatment promotes, for example, uniform
crystallinity and/or coating densification. The rapid melting and
solidification for certain particles can provide enhanced
properties associated with the metal and/or metal oxide coating
such as barrier properties, binding properties and crystalline
surface formation. The short residence times in the reaction zones
allow for rapid treatments. Further the processing conditions can
be adjusted to selective melt and resolidificate and crystallize
the surface and near surface of the particles. Moreover, surface
leveling can be achieved which results in a uniform surface with
minimal defects. Among other things, this may help to avoid
agglomeration of particles.
[0019] The process comprises
(A) providing coated glass flakes, (B) entraining said coated glass
flakes in a stream of gas for transport to a plasma torch; (C)
creating a plasma in said stream of gas to heat the outer surface
of the coated glass flakes; (D) permitting said coated glass flakes
to cool; and (E) collecting said coated glass flakes.
[0020] The plasma torch is preferably an induction plasma torch.
The preferred induction plasma torches for use in the process of
the present invention are available from Tekna Plasma Systems, Inc.
of Sherbrooke, Quebec, Canada. Boulos et al., U.S. Pat. No.
5,200,595, is hereby incorporated by reference for its teachings
relative to the construction and operation of plasma induction
torches.
[0021] In one preferred embodiment of the present invention, the
pigments comprise on the glass substrate
(a) a dielectric layer, (b) a metal layer, and (c) a dielectric
layer. Such pigments have high infrared reflectivity and high
visible transmission.
[0022] Preferably, metallic silver is used as the metal layer
because it offers high reflectivity to infrared radiation together
with high transmission to solar radiation providing its reflection
losses are minimized. Although high purity metallic silver films
are preferred, certain impurities and/or alloying metals can be
tolerated as long as they do not significantly reduce the infrared
reflectivity or significantly increase the visible absorptivity.
The thickness of the metallic silver layer is within a range of
from 3 to 20 nm.
[0023] Suitable materials for layer (c) are materials which are
transparent to solar and infrared radiation in the thicknesses
used. Additionally, these materials serve as anti-reflection
coatings to minimize the reflection of visible light by the silver
layer, and these materials preferably have high indices of
refraction. Some suitable materials for layer (c) include, but are
not limited to, titanium dioxide, silicon dioxide, silicon
monoxide, bismuth oxide, tin oxide, indium oxide, chromium oxide,
zinc sulfide and magnesium fluoride. Titanium dioxide is a
preferred material because of its high refractive index and because
it has been found to have minimum interdiffusion with silver.
[0024] Suitable materials for layer (a) are transparent materials
which cooperate with layer (a) to minimize visible light reflection
losses by the silver layer. The transparent materials suitable for
layer (c) are also suitable for layer (a), and titanium dioxide is
also a preferred material for this layer. Layer (a) can be formed
from the same material as layer (c), or from a different material
in which case it would probably have a different thickness.
[0025] The thicknesses for layer (c) and layer (a) are chosen to
maximize solar transmission and infrared reflectivity. It has been
found that a thickness of from about 15 to about 50 nm is suitable
for layer (c). The thickness of layer (a) is then chosen based upon
a number of considerations such as whether it is desired to achieve
the optimum solar transmission, the optimum ratio of transmission
to thermal reflectivity or some combination between these optimized
values.
[0026] In most cases, the optical properties desired can be
achieved by choosing a thickness of layer of between about 15 nm
and about 50 nm.
[0027] In one preferred embodiment of the present invention, the
interference pigments comprise materials having a "high" index of
refraction, which is defined herein as an index of refraction of
greater than about 1.65, and optionally materials having a "low"
index of refraction, which is defined herein as an index of
refraction of about 1.65 or less. Various (dielectric) materials
that can be utilized including inorganic materials such as metal
oxides, metal suboxides, metal fluorides, metal oxyhalides, metal
sulfides, metal chalcogenides, metal nitrides, metal oxynitrides,
metal carbides, combinations thereof, and the like, as well as
organic dielectric materials. These materials are readily available
and easily applied by physical, or chemical vapor deposition
processes, or by wet chemical coating processes.
[0028] Optionally a SiO.sub.2 layer can be arranged between the
glass substrate and the materials having a "high" index of
refraction. By applying a SiO.sub.2 layer on the glass substrate
the glass surface is protected against chemical alteration, such
as, for example, swelling and leaching of glass components. The
thickness of the SiO.sub.2 layer is in the range of 5 to 200 nm,
especially 20 to 150 nm. The SiO.sub.2 layer is preferably prepared
by using an organic silane compound, such as tetraethoxy silane
(TEOS). The SiO.sub.2 layer can be replaced by thin layers
(thickness 1 to 20 nm) of Al.sub.2O.sub.3, Fe.sub.2O.sub.3 or
ZrO.sub.2.
[0029] Furthermore, the SiO.sub.2-coated, or TiO.sub.2-coated glass
flakes may, as described in EP-A-0 982 376, be coated with a
nitrogen-doped carbon layer. The process described in EP-A-0 982
376 comprises the following steps:
(a) suspending the SiO.sub.2, or TiO.sub.2 coated glass flakes in a
liquid, (b) where appropriate adding a surface-modifier and/or a
polymerization catalyst, (c), before or after step (b), adding one
or more polymers comprising nitrogen and carbon atoms, or one or
more monomers capable of forming such polymers, (d) forming a
polymeric coating on the surface of the flakes, (e) isolating the
coated flakes and (f) heating the coated flakes to a temperature of
from 100 to 600.degree. C. in a gaseous atmosphere.
[0030] The polymer may be a polypyrrole, a polyamide, a
polyaniline, a polyurethane, a nitrile rubber or a
melamine-formaldehyde resin, preferably a polyacrylonitrile, or the
monomer is a pyrrole derivative, an acrylonitrile, a
methacrylonitrile, a crotonitrile, an acrylamide, a methacrylamide
or a crotonamide, preferably an acrylonitrile, methacrylonitrile or
crotonitrile, most preferably an acrylonitrile.
[0031] Preferably, the flakes are heated in step (f) initially to
from 100.degree. C. to 300.degree. C. in an oxygen-containing
atmosphere and then to from 200 to 600.degree. C. in an inert gas
atmosphere.
[0032] The present invention therefore relates also to pigments
based on the glass flakes according to the invention comprising
over the entire surface of the silicon oxide, or titanium oxide
coated glass flakes a layer consisting of from 50 to 95% by weight
carbon, from 5 to 25% by weight nitrogen and from 0 to 25% by
weight of the elements hydrogen, oxygen and/or sulfur, the
percentage by weight data relating to the total weight of the layer
(PAN).
[0033] The thickness of the nitrogen-doped carbon layer is
generally from 10 to 150 nm, preferably from 30 to 70 nm. In said
embodiment preferred pigments have the following layer structure:
glass substrate/TiO.sub.2/PAN, glass
substrate/TiO.sub.2/PAN/TiO.sub.2, glass
substrate/TiO.sub.2/PAN/SiO.sub.2/PAN.
[0034] In an especially preferred embodiment, the interference
pigments on the basis of the glass substrate comprise a further
layer of a dielectric material having a "high" refractive index,
that is to say a refractive index greater than about 1.65,
preferably greater than about 2.0, most preferred greater than
about 2.2, which is applied to the entire surface of the glass
substrate. Examples of such a dielectric material are zinc sulfide
(ZnS), zinc oxide (ZnO), zirconium oxide (ZrO.sub.2), titanium
dioxide (TiO.sub.2), carbon, indium oxide (In.sub.2O.sub.3), indium
tin oxide (ITO), tantalum pentoxide (Ta.sub.2O.sub.5), chromium
oxide (Cr.sub.2O.sub.3), cerium oxide (CeO.sub.2), yttrium oxide
(Y.sub.2O.sub.3), europium oxide (Eu.sub.2O.sub.3), iron oxides
such as iron(II)/iron(III) oxide (Fe.sub.3O.sub.4) and iron(III)
oxide (Fe.sub.2O.sub.3), hafnium nitride (HfN), hafnium carbide
(HfC), hafnium oxide (HfO.sub.2), lanthanum oxide
(La.sub.2O.sub.3), magnesium oxide (MgO), neodymium oxide
(Nd.sub.2O.sub.3), praseodymium oxide (Pr.sub.6O.sub.11), samarium
oxide (Sm.sub.2O.sub.3), antimony trioxide (Sb.sub.2O.sub.3),
silicon monoxides (SiO), selenium trioxide (Se.sub.2O.sub.3), tin
oxide (SnO.sub.2), tungsten trioxide (WO3), or combinations
thereof. The dielectric material is preferably a metal oxide. It
being possible for the metal oxide to be a single oxide or a
mixture of oxides, with or without absorbing properties, for
example, TiO.sub.2, ZrO.sub.2, Fe.sub.2O.sub.3, Fe.sub.3O.sub.4,
Cr.sub.2O.sub.3 or ZnO, with TiO.sub.2 being especially
preferred.
[0035] It is possible to obtain pigments that are more intense in
colour and more transparent by applying, on top of the TiO.sub.2
layer, a metal oxide of low refractive index, such as SiO.sub.2,
Al.sub.2O.sub.3, AlOOH, B.sub.2O.sub.3 or a mixture thereof,
preferably SiO.sub.2, and optionally applying a further TiO.sub.2
layer on top of the latter layer (EP-A-892832, EP-A-753545,
WO93/08237, WO98/53011, WO9812266, WO9838254, WO99/20695,
WO00/42111, and EP-A-1213330). Nonlimiting examples of suitable low
index dielectric materials that can be used include silicon dioxide
(SiO.sub.2), aluminum oxide (Al.sub.2O.sub.3), and metal fluorides
such as magnesium fluoride (MgF.sub.2), aluminum fluoride
(AlF.sub.3), cerium fluoride (CeF.sub.3), lanthanum fluoride
(LaF.sub.3), sodium aluminum fluorides (e.g., Na.sub.3AlF.sub.6 or
Na.sub.5Al.sub.3F.sub.14), neodymium fluoride (NdF.sub.3), samarium
fluoride (SmF.sub.3), barium fluoride (BaF.sub.2), calcium fluoride
(CaF.sub.2), lithium fluoride (LiF), combinations thereof, or any
other low index material having an index of refraction of about
1.65 or less. For example, organic monomers and polymers can be
utilized as low index materials, including dienes or alkenes such
as acrylates (e.g., methacrylate), polymers of perfluoroalkenes,
polytetrafluoroethylene (TEFLON), polymers of fluorinated ethylene
propylene (FEP), parylene, p-xylene, combinations thereof, and the
like. Additionally, the foregoing materials include evaporated,
condensed and cross-linked transparent acrylate layers, which may
be deposited by methods described in U.S. Pat. No. 5,877,895, the
disclosure of which is incorporated herein by reference.
[0036] Accordingly, preferred interference pigments comprise
besides (a) a metal oxide of high refractive index in addition (b)
a metal oxide of low refractive index, wherein the difference of
the refractive indices is at least 0.1.
[0037] Pigments on the basis of glass substrates, which have been
coated by a wet chemical method, in the indicated order are
particularly preferred:
TiO.sub.2, (SnO.sub.2)TiO.sub.2 (substrate: glass; layer:
(SnO.sub.2)TiO.sub.2, preferably in the rutile modification),
Fe.sub.2O.sub.3, Fe.sub.3O.sub.4, TiFe.sub.2O.sub.5,
Cr.sub.2O.sub.3, ZrO.sub.2, Sn(Sb)O.sub.2, BiOCl, Al.sub.2O.sub.3,
Ce.sub.2S.sub.3, MoS.sub.2, Fe.sub.2O.sub.3.TiO.sub.2 (substrate:
glass; mixed layer of Fe.sub.2O.sub.3 and TiO.sub.2),
TiO.sub.2/Fe.sub.2O.sub.3 (substrate: glass; first layer:
TiO.sub.2; second layer: Fe.sub.2O.sub.3), TiO.sub.2/Berlin blau,
TiO.sub.2/Cr.sub.2O.sub.3, or TiO.sub.2/FeTiO.sub.3. In general the
layer thickness ranges from 1 to 1000 nm, preferably from 1 to 300
nm.
[0038] In another particularly preferred embodiment the present
invention relates to interference pigments containing at least
three alternating layers of high and low refractive index, such as,
for example, TiO.sub.2/SiO.sub.2/TiO.sub.2,
(SnO.sub.2)TiO.sub.2/SiO.sub.2/TiO.sub.2,
TiO.sub.2/SiO.sub.2/TiO.sub.2/SiO.sub.2/TiO.sub.2,
Fe.sub.2O.sub.3/SiO.sub.2/TiO.sub.2, or
TiO.sub.2/SiO.sub.2/Fe.sub.2O.sub.3.
[0039] Preferably the layer structure is as follows:
(a) a coating having a refractive index >1.65, (b) a coating
having a refractive index .ltoreq.1.65, (c) a coating having a
refractive index >1.65, and (d) optionally an outer protective
layer.
[0040] The thickness of the individual layers of high and low
refractive index on the base substrate is essential for the optical
properties of the pigment. The thickness of the individual layers,
especially metal oxide layers, depends on the field of use and is
generally 10 to 1000 nm, preferably 15 to 800 nm, in particular 20
to 600 nm.
[0041] The thickness of layer (A) is 10 to 550 nm, preferably 15 to
400 nm and, in particular, 20 to 350 nm. The thickness of layer (B)
is 10 to 1000 nm, preferably 20 to 800 nm and, in particular, 30 to
600 nm. The thickness of layer (C) is 10 to 550 nm, preferably 15
to 400 nm and, in particular, 20 to 350 nm.
[0042] Particularly suitable materials for layer (A) are metal
oxides, metal sulfides, or metal oxide mixtures, such as TiO.sub.2,
Fe.sub.2O.sub.3, TiFe.sub.2O.sub.5, Fe.sub.3O.sub.4, BiOCl, CoO,
Co.sub.3O.sub.4, Cr.sub.2O.sub.3, VO.sub.2, V.sub.2O.sub.3,
Sn(Sb)O.sub.2, SnO.sub.2, ZrO.sub.2, iron titanates, iron oxide
hydrates, titanium suboxides (reduced titanium species having
oxidation states from 2 to <4), bismuth vanadate, cobalt
aluminate, and also mixtures or mixed phases of these compounds
with one another or with other metal oxides. Metal sulfide coatings
are preferably selected from sulfides of tin, silver, lanthanum,
rare earth metals, preferably cerium, chromium, molybdenum,
tungsten, iron, cobalt and/or nickel.
[0043] Particularly suitable materials for layer (B) are metal
oxides or the corresponding oxide hydrates, such as SiO.sub.2,
MgF.sub.2, Al.sub.2O.sub.3, AlOOH, B.sub.2O.sub.3 or a mixture
thereof, preferably SiO.sub.2.
[0044] Particularly suitable materials for layer (C) are colorless
or colored metal oxides, such as TiO.sub.2, Fe.sub.2O.sub.3,
TiFe.sub.2O.sub.5, Fe.sub.3O.sub.4, BiOCl, CoO, Co.sub.3O.sub.4,
Cr.sub.2O.sub.3, VO.sub.2, V.sub.2O.sub.3, Sn(Sb)O.sub.2,
SnO.sub.2, ZrO.sub.2, iron titanates, iron oxide hydrates, titanium
suboxides (reduced titanium species having oxidation states from 2
to <4), bismuth vanadate, cobalt aluminate, and also mixtures or
mixed phases of these compounds with one another or with other
metal oxides. The TiO.sub.2 layers can additionally contain an
absorbing material, such as carbon, selectively absorbing
colorants, selectively absorbing metal cations, can be coated with
absorbing material, or can be partially reduced.
[0045] Interlayers of absorbing or nonabsorbing materials can be
present between layers (A), (B), (C) and (D). The thickness of the
interlayers is 1 to 50 nm, preferably 1 to 40 nm and, in
particular, 1 to 30 nm. Such an interlayer can, for example,
consist of SnO.sub.2. It is possible to force the rutile structure
to be formed by adding small amounts of SnO.sub.2 (see, for
example, WO93/08237).
[0046] In this embodiment preferred interference pigments have the
following layer structure:
TABLE-US-00001 glass TiO.sub.2 SiO.sub.2 TiO.sub.2 glass TiO.sub.2
SiO.sub.2 Fe.sub.2O.sub.3 glass TiO.sub.2 SiO.sub.2
TiO.sub.2/Fe.sub.2O.sub.3 glass TiO.sub.2 SiO.sub.2 (Sn,Sb)O.sub.2
glass (Sn,Sb)O.sub.2 SiO.sub.2 TiO.sub.2 glass Fe.sub.2O.sub.3
SiO.sub.2 (Sn,Sb)O.sub.2 glass TiO.sub.2/Fe.sub.2O.sub.3 SiO.sub.2
TiO.sub.2/Fe.sub.2O.sub.3 glass TiO.sub.2 SiO.sub.2 MoS.sub.2 glass
TiO.sub.2 SiO.sub.2 Cr.sub.2O.sub.3 glass Cr.sub.2O.sub.3 SiO.sub.2
TiO.sub.2 glass Fe.sub.2O.sub.3 SiO.sub.2 TiO.sub.2 glass TiO.sub.2
Al.sub.2O.sub.3 TiO.sub.2 glass Fe.sub.2TiO.sub.5 SiO.sub.2
TiO.sub.2 glass TiO.sub.2 SiO.sub.2 Fe.sub.2TiO.sub.5/TiO.sub.2
glass TiO suboxides SiO.sub.2 TiO suboxides glass TiO.sub.2
SiO.sub.2 TiO.sub.2 + SiO.sub.2 + TiO.sub.2 + Prussian Blue glass
TiO.sub.2 SiO.sub.2 TiO.sub.2 + SiO.sub.2 + TiO.sub.2 glass
TiO.sub.2 + SiO.sub.2 + SiO.sub.2 TiO.sub.2 + SiO.sub.2 + TiO.sub.2
TiO.sub.2
[0047] The pigments of the present invention are characterized by
the precisely defined thickness and smooth surface of the thin
glass flakes (the average thickness should be between 50 and 400
nm+/-40% of the average thickness, preferably less than about 220
nm, wherein a deviation from the average thickness of +/-10% is
preferred).
[0048] The metal oxide layers can be applied by CVD chemical vapour
deposition) or by wet chemical coating. The metal oxide layers can
be obtained by decomposition of metal carbonyls in the presence of
water vapour (relatively low molecular weight metal oxides such as
magnetite) or in the presence of oxygen and, where appropriate,
water vapour (e.g. nickel oxide and cobalt oxide). The metal oxide
layers are especially applied by means of oxidative gaseous phase
decomposition of metal carbonyls (e.g. iron pentacarbonyl, chromium
hexacarbonyl; EP-A-45 851), by means of hydrolytic gaseous phase
decomposition of metal alcoholates (e.g. titanium and zirconium
tetra-n- and -iso-propanolate; DE-A-41 40 900) or of metal halides
(e.g. titanium tetrachloride; EP-A-338 428), by means of oxidative
decomposition of organyl tin compounds (especially alkyl tin
compounds such as tetrabutyltin and tetramethyltin; DE-A-44 03 678)
or by means of the gaseous phase hydrolysis of organyl silicon
compounds (especially di-tert-butoxyacetoxysilane) described in
EP-A-668 329, it being possible for the coating operation to be
carried out in a fluidised-bed reactor (EP-A-045 851 and EP-A-106
235). Al.sub.2O.sub.3 layers (B) can advantageously be obtained by
controlled oxidation during the cooling of aluminium-coated
pigments, which is otherwise carried out under inert gas (DE-A-195
16 181).
[0049] Phosphate-, chromate- and/or vanadate-containing and also
phosphate- and SiO.sub.2-containing metal oxide layers can be
applied in accordance with the passivation methods described in
DE-A-42 36 332 and in EP-A-678 561 by means of hydrolytic or
oxidative gaseous phase decomposition of oxide-halides of the
metals (e.g. CrO.sub.2Cl.sub.2, VOCl.sub.3), especially of
phosphorus oxyhalides (e.g. POCl.sub.3), phosphoric and phosphorous
acid esters (e.g. di- and tri-methyl and di- and tri-ethyl
phosphite) and of amino-group-containing organyl silicon compounds
(e.g. 3-aminopropyl-triethoxy- and -trimethoxy-silane).
[0050] Layers of oxides of the metals zirconium, titanium, iron and
zinc, oxide hydrates of those metals, iron titanates, titanium
suboxides or mixtures thereof are preferably applied by
precipitation by a wet chemical method, it being possible, where
appropriate, for the metal oxides to be reduced. In the case of the
wet chemical coating, the wet chemical coating methods developed
for the production of pearlescent pigments may be used; these are
described, for example, in DE-A-14 67 468, DE-A-19 59 988, DE-A-20
09 566, DE-A-22 14 545, DE-A-22 15 191, DE-A-22 44 298, DE-A-23 13
331, DE-A-25 22 572, DE-A-31 37 808, DE-A-31 37 809, DE-A-31 51
343, DE-A-31 51 354, DE-A-31 51 355, DE-A-32 11 602 and DE-A-32 35
017, DE 195 99 88, WO 93/08237, WO 98/53001 and WO03/6558.
[0051] The metal oxide of high refractive index is preferably
TiO.sub.2 and/or iron oxide, and the metal oxide of low refractive
index is preferably SiO.sub.2. Layers of TiO.sub.2 can be in the
rutile or anastase modification, wherein the rutile modification is
preferred. TiO.sub.2 layers can also be reduced by known means, for
example ammonia, hydrogen, hydrocarbon vapor or mixtures thereof,
or metal powders, as described in EP-A-735,114, DE-A-3433657,
DE-A-4125134, EP-A-332071, EP-A-707,050 or WO93/19131.
[0052] For the purpose of coating, the substrate particles are
suspended in water and one or more hydrolysable metal salts are
added at a pH suitable for the hydrolysis, which is so selected
that the metal oxides or metal oxide hydrates are precipitated
directly onto the particles without subsidiary precipitation
occurring. The pH is usually kept constant by simultaneously
metering in a base. The pigments are then separated off, washed,
dried and, where appropriate, calcinated, it being possible to
optimise the calcinating temperature with respect to the coating in
question. If desired, after individual coatings have been applied,
the pigments can be separated off, dried and, where appropriate,
calcinated, and then again re-suspended for the purpose of
precipitating further layers.
[0053] The metal oxide layers are also obtainable, for example, in
analogy to a method described in DE-A-195 01 307, by producing the
metal oxide layer by controlled hydrolysis of one or more metal
acid esters, where appropriate in the presence of an organic
solvent and a basic catalyst, by means of a sol-gel process.
Suitable basic catalysts are, for example, amines, such as
triethylamine, ethylenediamine, tributylamine, dimethylethanolamine
and methoxypropylamine. The organic solvent is a water-miscible
organic solvent such as a C.sub.1-4alcohol, especially
isopropanol.
[0054] Suitable metal acid esters are selected from alkyl and aryl
alcoholates, carboxylates, and carboxyl-radical- or alkyl-radical-
or aryl-radical-substituted alkyl alcoholates or carboxylates of
vanadium, titanium, zirconium, silicon, aluminium and boron. The
use of triisopropyl aluminate, tetraisopropyl titanate,
tetraisopropyl zirconate, tetraethyl orthosilicate and triethyl
borate is preferred. In addition, acetylacetonates and
acetoacetylacetonates of the aforementioned metals may be used.
Preferred examples of that type of metal acid ester are zirconium
acetylacetonate, aluminium acetylacetonate, titanium
acetylacetonate and diisobutyloleyl acetoacetylaluminate or
diisopropyloleyl acetoacetylacetonate and mixtures of metal acid
esters, for example Dynasil.RTM. (Huls), a mixed aluminium/silicon
metal acid ester.
[0055] As a metal oxide having a high refractive index, titanium
dioxide is preferably used, the method described in U.S. Pat. No.
3,553,001 being used, in accordance with an embodiment of the
present invention, for application of the titanium dioxide
layers.
[0056] An aqueous titanium salt solution is slowly added to a
suspension of the material being coated, which suspension has been
heated to about 50-100.degree. C., especially 70-80.degree. C., and
a substantially constant pH value of about from 0.5 to 5,
especially about from 1.2 to 2.5, is maintained by simultaneously
metering in a base such as, for example, aqueous ammonia solution
or aqueous alkali metal hydroxide solution. As soon as the desired
layer thickness of precipitated TiO.sub.2 has been achieved, the
addition of titanium salt solution and base is stopped. Addition of
a precursor for Al.sub.2O.sub.3 or MgO in the starting solutions is
a way for improving the morphology of the TiO.sub.2 layer.
[0057] This method, also referred to as the "titration method", is
distinguished by the fact that an excess of titanium salt is
avoided. That is achieved by feeding in for hydrolysis, per unit
time, only that amount which is necessary for even coating with the
hydrated TiO.sub.2 and which can be taken up per unit time by the
available surface of the particles being coated. In principle, the
anatase form of TiO.sub.2 forms on the surface of the starting
pigment. By adding small amounts of SnO.sub.2, however, it is
possible to force the rutile structure to be formed. For example,
as described in WO 93/08237, tin dioxide can be deposited before
titanium dioxide precipitation and the product coated with titanium
dioxide can be calcined at from 800 to 900.degree. C.
[0058] The TiO.sub.2 can optionally be reduced by usual procedures:
U.S. Pat. No. 4,948,631 (NH.sub.3, 750-850.degree. C.), WO93/19131
(H.sub.2, >900.degree. C.) or DE-A-19843014 (solid reduction
agent, such as, for example, silicon, >600.degree. C.).
[0059] Where appropriate, an SiO.sub.2 (protective) layer can be
applied on top of the titanium dioxide layer, for which the
following method may be used: A soda waterglass solution is metered
into a suspension of the material being coated, which suspension
has been heated to about 50-100.degree. C., especially
70-80.degree. C. The pH is maintained at from 4 to 10, preferably
from 6.5 to 8.5, by simultaneously adding 10% hydrochloric acid.
After addition of the waterglass solution, stirring is carried out
for 30 minutes.
[0060] It is possible to obtain pigments that are more intense in
colour and more transparent by applying, on top of the TiO.sub.2
layer, a metal oxide of "low" refractive index, that is to say a
refractive index smaller than about 1.65, such as SiO.sub.2,
Al.sub.2O.sub.3, AlOOH, B.sub.2O.sub.3 or a mixture thereof,
preferably SiO.sub.2, and applying a further Fe.sub.2O.sub.3 and/or
TiO.sub.2 layer on top of the latter layer. Such multi-coated
interference pigments comprising a glass substrate and alternating
metal oxide layers of with high and low refractive index can be
prepared in analogy to the processes described in WO98/53011 and
WO99/20695.
[0061] It is, in addition, possible to modify the powder colour of
the pigment by applying further layers such as, for example,
coloured metal oxides or Berlin Blue, compounds of transition
metals, e.g. Fe, Cu, Ni, Co, Cr, or organic compounds such as dyes
or colour lakes.
[0062] In addition, the pigment according to the invention can also
be coated with poorly soluble, firmly adhering, inorganic or
organic colourants. Preference is given to the use of colour lakes
and, especially, aluminium colour lakes. For that purpose an
aluminium hydroxide layer is precipitated, which is, in a second
step, laked by using a colour lake (DE-A-24 29 762 and DE-A-29 28
287).
[0063] Furthermore, the pigment according to the invention may also
have an additional coating with complex salt pigments, especially
cyanoferrate complexes (EP-A-141 173 and DE-A-23 13 332).
[0064] To enhance the weather and light stability the multiplayer
glass flakes can be, depending on the field of application,
subjected to a surface treatment. Useful surface treatments are,
for example, described in DE-A-2215191, DE-A-3151354, DE-A-3235017,
DE-A-3334598, DE-A-4030727, EP-A-649886, WO97/29059, WO99/57204,
and U.S. Pat. No. 5,759,255. Said surface treatment might also
facilitate the handling of the pigment, especially its
incorporation into various application media.
[0065] The glass flakes are prepared, for example, by a process
described in WO2004056716. By said process flakes may be produced
with average thicknesses below 250 nm and with thickness variations
as low as 10 percent.
[0066] The modification of the glass composition is possible in
order to adjust the index of refraction between 1.45 and 1.65.
Examples of suitable glass materials are C glass [SiO.sub.2
(65-70%), Al.sub.2O.sub.3 (2-6%), CaO (4-9%), MgO (0-5%),
B.sub.2O.sub.3 (2-7%), Na.sub.2O & K.sub.2O (9-13%), ZnO
(1-6%)] and ECR glass [SiO.sub.2 (63-70%), Al.sub.2O.sub.3 (3-6%),
CaO (4-7%), MgO (1-4%), B.sub.2O.sub.3 (2-5%), Na.sub.2O (9-12%),
K.sub.2O (0-3%), TiO.sub.2 (0-4%), ZnO (1-5%)]. An especially
preferred glass material is ECR glass having >0.1% TiO.sub.2,
especially below 1% TiO.sub.2. The softening temperature according
to ASTM C-338 of the ECR glass is below 800.degree. C., especially
below 700.degree. C. According to ASTM C-338 the softening point
temperature is the temperature at which a uniform fiber of glass
(0.65 mm in diameter by 23.5 cm long) elongates under its own
weight at a rate of 1.0 millimeters per minute when the upper 10 cm
of its length is heated in a special furnace at the rate of
5.degree. C. per minute.
[0067] Such ECR glass flakes are, for example, available from
GlassFlake Ltd.:
GF10 has an average thickness of about 210 nm and a BET of 2.2
m.sup.2/g. GF350 has an average thickness of about 390 nm and a BET
of 1.2 m.sup.2/g.
[0068] Both products are based on ECR glass, which has a softening
temperature according to ASTM C 338 of about 688.degree. C.
[0069] If ECR glass flakes are used, the rutile phase of TiO.sub.2
is already obtained at room temperature when SnO.sub.2 is present.
A calcination is nevertheless required in order to remove the water
trapped within the TiO.sub.2 layer.
[0070] In a preferred embodiment of the present invention is
directed to pigments which contain a core of glass and comprise a
mixed layer of Al.sub.2O.sub.3/TiO.sub.2. The mixed layer can
contain up to 20 mol % Al.sub.2O.sub.3. The mixed layer of
Al.sub.2O.sub.3/TiO.sub.2 is obtained by slowly adding an aqueous
aluminum and titanium salt solution to a suspension of the material
being coated, which suspension has been heated to about
50-100.degree. C., especially 70-80.degree. C., and maintaining a
substantially constant pH value of about from 0.5 to 5, especially
about from 1.2 to 2.5, by simultaneously metering in a base such
as, for example, aqueous ammonia solution or aqueous alkali metal
hydroxide solution. As soon as the desired layer thickness of
precipitated Al.sub.2O.sub.3/TiO.sub.2 has been achieved, the
addition of titanium and aluminum salt solution and base is
stopped.
[0071] The thickness of the mixed layer of
Al.sub.2O.sub.3/TiO.sub.2 is in general in the range of 20 to 200
nm, especially 50 to 150 nm. Preferably the pigments comprise a
TiO.sub.2 layer on top of the mixed layer of
Al.sub.2O.sub.3/TiO.sub.2 having a thickness of 1 to 50 nm,
especially 10 to 20 nm. By varying the thickness of the mixed layer
of Al.sub.2O/TiO.sub.2 the flop of the pigments can be enhanced and
controlled as desired.
[0072] In another preferred embodiment of the present invention is
directed to pigments which contain a core of glass and consist of
subsequent layers of TiO.sub.2/SnO.sub.2/TiO.sub.2, wherein the
TiO.sub.2 layer next to the glass substrate has a thickness of 1 to
20 nm and is preferably prepared by using titanium alcoholates,
especially tetraisopropyl titanate.
[0073] The BET of the glass flakes made by the above mentioned
process is between 1 and 50 m.sup.2/g. The glass flakes show a
superior planarity and smoothness (surface microstructure) which
can be expressed by the ratio BET (specific surface area) to WCA
(water covering area). The values are around 3 which indicate the
optimum suitability of the material.
[0074] The flakes used in the present invention are not of a
uniform shape. Nevertheless, for purposes of brevity, the flakes
will be referred to as having a "diameter." The glass flakes have a
high plane-parallelism and a defined thickness in the range of
.+-.10%, especially .+-.5% of the average thickness. The glass
flakes have an average thickness of <1 .mu.m, especially of from
20 to 400 nm, especially from 20 to 300 nm, most preferred 50 to
220 nm. It is presently preferred that the diameter of the flakes
be in a preferred range of about 1-60 .mu.m with a more preferred
range of about 540 .mu.m. Thus, the aspect ratio of the flakes of
the present invention is in a preferred range of about 5 to 3000.
If a TiO.sub.2 layer is deposited as a material of high refractive
index, the TiO.sub.2 layer has a thickness of 20 to 200 nm,
especially 20 to 100 nm, and more especially 20 to 50 nm.
[0075] If the glass substrates of the present invention are used,
interference pigments having superior brilliance, clear and intense
colors, intense color flop, improved color strength and/or color
purity can be obtained.
[0076] In another preferred embodiment of the present invention the
glass flakes have an average thickness of from 20 to 200 nm,
especially from 40 to 150 nm, most preferred 60 to 120 nm. The
glass flakes have a high plane-parallelism and a defined thickness
in the range of .+-.40%, especially .+-.10% of the average
thickness. It is presently preferred that the diameter of the
flakes be in a preferred range of about 1 to 60 .mu.m, especially 2
to 50 .mu.m, with a more preferred range of about 5-40 .mu.m. Thus,
the aspect ratio of the flakes of the present invention is in a
preferred range of about 4 to 1250 with a more preferred range of
about 42 to 670. If a TiO.sub.2 layer is deposited as a material of
high refractive index, the TiO.sub.2 layer has a thickness of 20 to
200 nm, especially 50 to 200 nm. The total thickness of the
TiO.sub.2-coated glass flakes is especially 150 to 450 nm.
Starting, for example, from glass flakes having a thickness of 90
nm.+-.30% it is possible to obtain red (ca. 73 nm), green (ca. 150
nm), or blue (ca. 130 nm) interference pigments by selecting the
thickness of the TiO.sub.2 layer. Due to the small thickness
distribution of the glass flakes effect pigments result having a
high color purity.
[0077] The preferred designs for the inventive pigments are:
>3-<40 .mu.m diameter for automotive applications, or even
more preferred 10-35 .mu.m, and >3-<20 .mu.m diameter for
printing applications, preferred 5-20 .mu.m.
[0078] A metallic-like pearl effect can be obtained with glass
flakes having a homogenous TiO.sub.2 coating and a large thickness
distribution (large Gaussian thickness distribution of the glass
flakes). That is, a Gaussian distribution with a standard deviation
of 10 to 100 nm. The standard deviation is preferably above 20 nm
and most preferred above 50 nm. Instead of TiO.sub.2 any other
metal oxide having an index of refraction than the substrate can be
used. Examples are the metal oxides of high refractive index
mentioned above, such as TiO.sub.2, ZrO.sub.2, Fe.sub.2O.sub.3,
Fe.sub.3O.sub.4, Cr.sub.2O.sub.3, ZnO or a mixture of these oxides
or an iron titanate, an iron oxide hydrate, a titanium suboxide or
a mixture and/or mixed phase of these compounds.
[0079] That is, for a large Gaussian thickness distribution of the
glass flakes the color of the pigments does not depend on the
average thickness of the glass flakes. Metallic shades can be
obtained, for example, by mixing the GF10 (average thickness=210
nm) and GF35 (average thickness=350 nm) glass flakes after or
before deposition of the TiO.sub.2. It is a typical effect of
TiO.sub.2 thickness of about 40 nm. The ratio of GF10 to GF35 is
preferably 0.5:0.5.
[0080] Metallic or non-metallic, inorganic platelet-shaped
particles or pigments are effect pigments, (especially metal effect
pigments or interference pigments), that is to say, pigments that,
besides imparting colour to an application medium, impart
additional properties, for example angle dependency of the colour
(flop), lustre (not surface gloss) or texture. On metal effect
pigments, substantially oriented reflection occurs at directionally
oriented pigment particles. In the case of interference pigments,
the colour-imparting effect is due to the phenomenon of
interference of light in thin, highly refractive layers.
[0081] The (effect) pigments according to the invention can be used
for all customary purposes, for example for colouring polymers in
the mass, coatings (including effect finishes, including those for
the automotive sector) and printing inks (including offset
printing, intaglio printing, bronzing and flexographic printing),
and also, for example, for applications in cosmetics, in ink-jet
printing, for dyeing textiles, glazes for ceramics and glass as
well as laser marking of papers and plastics. Such applications are
known from reference works, for example "Industrielle Organische
Pigmente" (W. Herbst and K. Hunger, VCH Verlagsgesellschaft mbH,
Weinheim/New York, 2nd, completely revised edition, 1995). When the
pigments according to the invention are interference pigments
(effect pigments), they may be goniochromatic and result in
brilliant, highly saturated (lustrous) colours. They are
accordingly very especially suitable for combination with
conventional, transparent pigments, for example organic pigments
such as, for example, diketopyrrolopyrroles, quinacridones,
dioxazines, perylenes, isoindolinones etc., it being possible for
the transparent pigment to have a similar colour to the effect
pigment. Especially interesting combination effects are obtained,
however, in analogy to, for example, EP-A-388 932 or EP-A-402 943,
when the colour of the transparent pigment and that of the effect
pigment are complementary.
[0082] The pigments according to the invention can be used with
excellent results for pigmenting high molecular weight organic
material.
[0083] The high molecular weight organic material for the
pigmenting of which the pigments or pigment compositions according
to the invention may be used may be of natural or synthetic origin.
High molecular weight organic materials usually have molecular
weights of about from 10.sup.3 to 10.sup.8 g/mol or even more. They
may be, for example, natural resins, drying oils, rubber or casein,
or natural substances derived therefrom, such as chlorinated
rubber, oil-modified alkyd resins, viscose, cellulose ethers or
esters, such as ethylcellulose, cellulose acetate, cellulose
propionate, cellulose acetobutyrate or nitrocellulose, but
especially totally synthetic organic polymers (thermosetting
plastics and thermoplastics), as are obtained by polymerisation,
polycondensation or polyaddition. From the class of the
polymerisation resins there may be mentioned, especially,
polyolefins, such as polyethylene, polypropylene or
polyisobutylene, and also substituted polyolefins, such as
polymerisation products of vinyl chloride, vinyl acetate, styrene,
acrylonitrile, acrylic acid esters, methacrylic acid esters or
butadiene, and also copolymerisation products of the said monomers,
such as especially ABS or EVA.
[0084] From the series of the polyaddition resins and
polycondensation resins there may be mentioned, for example,
condensation products of formaldehyde with phenols, so-called
phenoplasts, and condensation products of formaldehyde with urea,
thiourea or melamine, so-called aminoplasts, and the polyesters
used as surface-coating resins, either saturated, such as alkyd
resins, or unsaturated, such as maleate resins; also linear
polyesters and polyamides, polyurethanes or silicones.
[0085] The said high molecular weight compounds may be present
singly or in mixtures, in the form of plastic masses or melts. They
may also be present in the form of their monomers or in the
polymerised state in dissolved form as film-formers or binders for
coatings or printing inks, such as, for example, boiled linseed
oil, nitrocellulose, alkyd resins, melamine resins and
urea-formaldehyde resins or acrylic resins.
[0086] Depending on the intended purpose, it has proved
advantageous to use the effect pigments or effect pigment
compositions according to the invention as toners or in the form of
preparations. Depending on the conditioning method or intended
application, R may be advantageous to add certain amounts of
texture-improving agents to the effect pigment before or after the
conditioning process, provided that this has no adverse effect on
use of the effect pigments for colouring high molecular weight
organic materials, especially polyethylene. Suitable agents are,
especially, fatty acids containing at least 18 carbon atoms, for
example stearic or behenic acid, or amides or metal salts thereof,
especially magnesium salts, and also plasticisers, waxes, resin
acids, such as abietic acid, rosin soap, alkylphenols or aliphatic
alcohols, such as stearyl alcohol, or aliphatic 1,2-dihydroxy
compounds containing from 8 to 22 carbon atoms, such as
1,2-dodecanediol, and also modified colophonium maleate resins or
fumaric acid colophonium resins. The texture-improving agents are
added in amounts of preferably from 0.1 to 30% by weight,
especially from 2 to 15% by weight, based on the end product.
[0087] The (effect) pigments according to the invention can be
added in any tinctorially effective amount to the high molecular
weight organic material being pigmented. A pigmented substance
composition comprising a high molecular weight organic material and
from 0.01 to 80% by weight, preferably from 0.1 to 30% by weight,
based on the high molecular weight organic material, of an pigment
according to the invention is advantageous. Concentrations of from
1 to 20% by weight, especially of about 10% by weight, can often be
used in practice.
[0088] High concentrations, for example those above 30% by weight,
are usually in the form of concentrates ("masterbatches") which can
be used as colorants for producing pigmented materials having a
relatively low pigment content, the pigments according to the
invention having an extraordinarily low viscosity in customary
formulations so that they can still be processed well.
[0089] For the purpose of pigmenting organic materials, the effect
pigments according to the invention may be used singly. It is,
however, also possible, in order to achieve different hues or
colour effects, to add any desired amounts of other
colour-imparting constituents, such as white, coloured, black or
effect pigments, to the high molecular weight organic substances in
addition to the effect pigments according to the invention. When
coloured pigments are used in admixture with the effect pigments
according to the invention, the total amount is preferably from 0.1
to 10% by weight, based on the high molecular weight organic
material. Especially high goniochromicity is provided by the
preferred combination of an effect pigment according to the
invention with a coloured pigment of another colour, especially of
a complementary colour, with colorations made using the effect
pigment and colorations made using the coloured pigment having, at
a measurement angle of 10.degree., a difference in hue (.DELTA.H*)
of from 20 to 340, especially from 150 to 210.
[0090] Preferably, the effect pigments according to the invention
are combined with transparent coloured pigments, it being possible
for the transparent coloured pigments to be present either in the
same medium as the effect pigments according to the invention or in
a neighbouring medium. An example of an arrangement in which the
effect pigment and the coloured pigment are advantageously present
in neighbouring media is a multi-layer effect coating.
[0091] The pigmenting of high molecular weight organic substances
with the pigments according to the invention is carried out, for
example, by admixing such a pigment, where appropriate in the form
of a masterbatch, with the substrates using roll mills or mixing or
grinding apparatuses. The pigmented material is then brought into
the desired final form using methods known per se, such as
calendering, compression moulding, extrusion, coating, pouring or
injection moulding. Any additives customary in the plastics
industry, such as plasticisers, fillers or stabilisers, can be
added to the polymer, in customary amounts, before or after
incorporation of the pigment. In particular, in order to produce
non-rigid shaped articles or to reduce their brittleness, it is
desirable to add plasticisers, for example esters of phosphoric
acid, phthalic acid or sebacic acid, to the high molecular weight
compounds prior to shaping.
[0092] For pigmenting coatings and printing inks, the high
molecular weight organic materials and the effect pigments
according to the invention, where appropriate together with
customary additives such as, for example, fillers, other pigments,
siccatives or plasticisers, are finely dispersed or dissolved in
the same organic solvent or solvent mixture, it being possible for
the individual components to be dissolved or dispersed separately
or for a number of components to be dissolved or dispersed
together, and only thereafter for all the components to be brought
together.
[0093] Dispersing an effect pigment according to the invention in
the high molecular weight organic material being pigmented, and
processing a pigment composition according to the invention, are
preferably carried out subject to conditions under which only
relatively weak shear forces occur so that the effect pigment is
not broken up into smaller portions.
[0094] Plastics comprising the pigment of the invention in amounts
of 0.1 to 50% by weight, in particular 0.5 to 7% by weight. In the
coating sector, the pigments of the invention are employed in
amounts of 0.1 to 10% by weight. In the pigmentation of binder
systems, for example for paints and printing inks for intaglio,
offset or screen printing, the pigment is incorporated into the
printing ink in amounts of 0.1 to 50% by weight, preferably 5 to
30% by weight and in particular 8 to 15% by weight.
[0095] The colorations obtained, for example in plastics, coatings
or printing inks, especially in coatings or printing inks, more
especially in coatings, may be distinguished by excellent
properties, especially by extremely high saturation, outstanding
fastness properties, high color purity and high
goniochromaticity.
[0096] When the high molecular weight material being pigmented is a
coating, it is especially a specialty coating, very especially an
automotive finish.
[0097] The effect pigments according to the invention are also
suitable for making-up the lips or the skin and for colouring the
hair or the nails.
[0098] The invention accordingly relates also to a cosmetic
preparation or formulation comprising from 0.0001 to 90% by weight
of a pigment, especially an effect pigment, according to the
invention and from 10 to 99.9999% of a cosmetically suitable
carrier material, based on the total weight of the cosmetic
preparation or formulation.
[0099] Such cosmetic preparations or formulations are, for example,
lipsticks, blushers, foundations, nail varnishes and hair
shampoos.
[0100] The pigments may be used singly or in the form of mixtures.
It is, in addition, possible to use pigments according to the
invention together with other pigments and/or colorants, for
example in combinations as described hereinbefore or as known in
cosmetic preparations. The cosmetic preparations and formulations
according to the invention preferably contain the pigment according
to the invention in an amount from 0.005 to 50% by weight, based on
the total weight of the preparation.
[0101] Suitable carrier materials for the cosmetic preparations and
formulations according to the invention include the customary
materials used in such compositions.
[0102] The cosmetic preparations and formulations according to the
invention may be in the form of, for example, sticks, ointments,
creams, emulsions, suspensions, dispersions, powders or solutions.
They are, for example, lipsticks, mascara preparations, blushers,
eye-shadows, foundations, eyeliners, powder or nail varnishes.
[0103] If the preparations are in the form of sticks, for example
lipsticks, eye-shadows, blushers or foundations, the preparations
consist for a considerable part of fatty components, which may
consist of one or more waxes, for example ozokerite, lanolin,
lanolin alcohol, hydrogenated lanolin, acetylated lanolin, lanolin
wax, beeswax, candelilla wax, microcrystalline wax, carnauba wax,
cetyl alcohol, stearyl alcohol, cocoa butter, lanolin fatty acids,
petrolatum, petroleum jelly, mono-, di- or tri-glycerides or fatty
esters thereof that are solid at 25.degree. C., silicone waxes,
such as methyloctadecane-oxypolysiloxane and
poly(dimethylsiloxy)-stearoxysiloxane, stearic acid
monoethanolamine, colophane and derivatives thereof, such as glycol
abietates and glycerol abietates, hydrogenated oils that are solid
at 25.degree. C., sugar glycerides and oleates, myristates,
lanolates, stearates and dihydroxystearates of calcium, magnesium,
zirconium and aluminium.
[0104] The fatty component may also consist of a mixture of at
least one wax and at least one oil, in which case the following
oils, for example, are suitable: paraffin oil, purcelline oil,
perhydrosqualene, sweet almond oil, avocado oil, calophyllum oil,
castor oil, sesame oil, jojoba oil, mineral oils having a boiling
point of about from 310 to 410.degree. C., silicone oils, such as
dimethylpolysiloxane, linoleyl alcohol, linolenyl alcohol, oleyl
alcohol, cereal grain oils, such as wheatgerm oil, isopropyl
lanolate, isopropyl palmitate, isopropyl myristate, butyl
myristate, cetyl myristate, hexadecyl stearate, butyl stearate,
decyl oleate, acetyl glycerides, octanoates and decanoates of
alcohols and polyalcohols, for example of glycol and glycerol,
ricinoleates of alcohols and polyalcohols, for example of cetyl
alcohol, isostearyl alcohol, isocetyl lanolate, isopropyl adipate,
hexyl laurate and octyl dodecanol.
[0105] The fatty components in such preparations in the form of
sticks may generally constitute up 5 to 99.91% by weight of the
total weight of the preparation.
[0106] The cosmetic preparations and formulations according to the
invention may additionally comprise further constituents, such as,
for example, glycols, polyethylene glycols, polypropylene glycols,
monoalkanolamides, non-coloured polymeric, inorganic or organic
fillers, preservatives, UV filters or other adjuvants and additives
customary in cosmetics, for example a natural or synthetic or
partially synthetic di- or tri-glyceride, a mineral oil, a silicone
oil, a wax, a fatty alcohol, a Guerbet alcohol or ester thereof, a
lipophilic functional cosmetic active ingredient, including
sun-protection filters, or a mixture of such substances.
[0107] A lipophilic functional cosmetic active ingredient suitable
for skin cosmetics, an active ingredient composition or an active
ingredient extract is an ingredient or a mixture of ingredients
that is approved for dermal or topical application. The following
may be mentioned by way of example: [0108] active ingredients
having a cleansing action on the skin surface and the hair; these
include all substances that serve to cleanse the skin, such as
oils, soaps, synthetic detergents and solid substances; [0109]
active ingredients having a deodorising and perspiration-inhibiting
action: they include antiperspirants based on aluminium salts or
zinc salts, deodorants comprising bactericidal or bacteriostatic
deodorising substances, for example triclosan, hexachlorophene,
alcohols and cationic substances, such as, for example, quaternary
ammonium salts, and odour absorbers, for example .RTM.Grillocin
(combination of zinc ricinoleate and various additives) or triethyl
citrate (optionally in combination with an antioxidant, such as,
for example, butyl hydroxytoluene) or ion-exchange resins; [0110]
active ingredients that offer protection against sunlight (UV
filters): suitable active ingredients are filter substances
(sunscreens) that are able to absorb UV radiation from sunlight and
convert it into heat; depending on the desired action, the
following light-protection agents are preferred: light-protection
agents that selectively absorb sunburn-causing high-energy UV
radiation in the range of approximately from 280 to 315 nm (UV-B
absorbers) and transmit the longer-wavelength range of, for
example, from 315 to 400 nm (UV-A range), as well as
light-protection agents that absorb only the longer-wavelength
radiation of the UV-A range of from 315 to 400 nm (UV-A absorbers);
suitable light-protection agents are, for example, organic UV
absorbers from the class of the p-aminobenzoic acid derivatives,
salicylic acid derivatives, benzophenone derivatives,
dibenzoylmethane derivatives, diphenyl acrylate derivatives,
benzofuran derivatives, polymeric UV absorbers comprising one or
more organosilicon radicals, cinnamic acid derivatives, camphor
derivatives, trianilino-s-triazine derivatives,
phenyl-benzimidazolesulfonic acid and salts thereof, menthyl
anthranilates, benzotriazole derivatives, and/or an inorganic
micropigment selected from aluminium oxide- or silicon
dioxide-coated TiO.sub.2, zinc oxide or mica; [0111] active
ingredients against insects (repellents) are agents that are
intended to prevent insects from touching the skin and becoming
active there; they drive insects away and evaporate slowly; the
most frequently used repellent is diethyl toluamide (DEET); other
common repellents will be found, for example, in "Pflegekosmetik"
(W. Raab and U. Kindl, Gustav-Fischer-Verlag Stuttgart/New York,
1991) on page 161; [0112] active ingredients for protection against
chemical and mechanical influences: these include all substances
that form a barrier between the skin and external harmful
substances, such as, for example, paraffin oils, silicone oils,
vegetable oils, PCL products and lanolin for protection against
aqueous solutions, film-forming agents, such as sodium alginate,
triethanolamine alginate, polyacrylates, polyvinyl alcohol or
cellulose ethers for protection against the effect of organic
solvents, or substances based on mineral oils, vegetable oils or
silicone oils as "lubricants" for protection against severe
mechanical stresses on the skin; [0113] moisturising substances:
the following substances, for example, are used as
moisture-controlling agents (moisturisers): sodium lactate, urea,
alcohols, sorbitol, glycerol, propylene glycol, collagen, elastin
and hyaluronic acid; [0114] active ingredients having a
keratoplastic effect: benzoyl peroxide, retinoic acid, colloidal
sulfur and resorcinol; [0115] antimicrobial agents, such as, for
example, triclosan or quaternary ammonium compounds; [0116] oily or
oil-soluble vitamins or vitamin derivatives that can be applied
dermally: for example vitamin A (retinol in the form of the free
acid or derivatives thereof), panthenol, pantothenic acid, folic
acid, and combinations thereof, vitamin E (tocopherol), vitamin F;
essential fatty acids; or niacinamide (nicotinic acid amide);
[0117] vitamin-based placenta extracts: active ingredient
compositions comprising especially vitamins A, C, E, B.sub.1,
B.sub.2, B.sub.6, B.sub.12, folic acid and biotin, amino acids and
enzymes as well as compounds of the trace elements magnesium,
silicon, phosphorus, calcium, manganese, iron or copper; [0118]
skin repair complexes: obtainable from inactivated and
disintegrated cultures of bacteria of the bifidus group; [0119]
plants and plant extracts: for example arnica, aloe, beard lichen,
ivy, stinging nettle, ginseng, henna, camomile, marigold, rosemary,
sage, horsetail or thyme; [0120] animal extracts: for example royal
jelly, propolis, proteins or thymus extracts; [0121] cosmetic oils
that can be applied dermally: neutral oils of the Miglyol 812 type,
apricot kernel oil, avocado oil, babassu oil, cottonseed oil,
borage oil, thistle oil, groundnut oil, gamma-oryzanol,
rosehip-seed oil, hemp oil, hazelnut oil, blackcurrant-seed oil,
jojoba oil, cherry-stone oil, salmon oil, linseed oil, cornseed
oil, macadamia nut oil, almond oil, evening primrose oil, mink oil,
olive oil, pecan nut oil, peach kernel oil, pistachio nut oil, rape
oil, rice-seed oil, castor oil, safflower oil, sesame oil, soybean
oil, sunflower oil, tea tree oil, grapeseed oil or wheatgerm
oil.
[0122] The preparations in stick form are preferably anhydrous but
may in certain cases comprise a certain amount of water which,
however, in general does not exceed 40% by weight, based on the
total weight of the cosmetic preparation.
[0123] If the cosmetic preparations and formulations according to
the invention are in the form of semi-solid products, that is to
say in the form of ointments or creams, they may likewise be
anhydrous or aqueous. Such preparations and formulations are, for
example, mascaras, eyeliners, foundations, blushers, eye-shadows,
or compositions for treating rings under the eyes.
[0124] If, on the other hand, such ointments or creams are aqueous,
they are especially emulsions of the water-in-oil type or of the
oil-in-water type that comprise, apart from the pigment, from 1 to
98.8% by weight of the fatty phase, from 1 to 98.8% by weight of
the aqueous phase and from 0.2 to 30% by weight of an
emulsifier.
[0125] Such ointments and creams may also comprise further
conventional additives, such as, for example, perfumes,
antioxidants, preservatives, gel-forming agents, UV filters,
colorants, pigments, pearlescent agents, non-coloured polymers as
well as inorganic or organic fillers. If the preparations are in
the form of a powder, they consist substantially of a mineral or
inorganic or organic filler such as, for example, talcum, kaolin,
starch, polyethylene powder or polyamide powder, as well as
adjuvants such as binders, colorants etc.
[0126] Such preparations may likewise comprise various adjuvants
conventionally employed in cosmetics, such as fragrances,
antioxidants, preservatives etc.
[0127] If the cosmetic preparations and formulations according to
the invention are nail varnishes, they consist essentially of
nitrocellulose and a natural or synthetic polymer in the form of a
solution in a solvent system, it being possible for the solution to
comprise other adjuvants, for example pearlescent agents.
[0128] In that embodiment, the coloured polymer is present in an
amount of approximately from 0.1 to 5% by weight.
[0129] The cosmetic preparations and formulations according to the
invention may also be used for colouring the hair, in which case
they are used in the form of shampoos, creams or gels that are
composed of the base substances conventionally employed in the
cosmetics industry and a pigment according to the invention.
[0130] The cosmetic preparations and formulations according to the
invention are prepared in conventional manner, for example by
mixing or stirring the components together, optionally with heating
so that the mixtures melt.
[0131] Various features and aspects of the present invention are
illustrated further in the examples that follow. While these
examples are presented to show one skilled in the art how to
operate within the scope of this invention, they are not to serve
as a limitation on the scope of the invention where such scope is
only defined in the claims. Unless otherwise indicated in the
following examples and elsewhere in the specification and claims,
all parts and percentages are by weight, temperatures are in
degrees centigrade and pressures are at or near atmospheric.
EXAMPLES
Example 1
[0132] 4.5 g of glass flakes GF10 (Glassflake Ltd., ECR glass
(softening temperature of about 688.degree. C.); average thickness
of about 210 nm and a BET of 2.2 m.sup.2/g), which have been milled
and sieved to obtain particles smaller than 100 microns and larger
than 20 microns, are mixed with 300 ml distilled water in a closed
reactor and heated at 75.degree. C. The pH is set to 1.15 and the
suspension is stirred at 350 rpm for 15 minutes. Then a preparation
comprising 9 g SnCl.sub.4.5H.sub.2O dissolved in 5 g HCl (37%) and
100 g distilled water is added (0.8 ml/minutes) during 15 minutes
while stirring at 350 rpm. Then the suspension is heated at
90.degree. C. while stirring during additional 15 minutes.
[0133] Then the pH is set to 1.6 and a preparation comprising 34 g
from TiOCl.sub.2, 32 g of HCl (37%) and 445 g of distilled water is
added at a rate of 0.8 ml/minutes during 6 hours. The powder
obtained after filtration and drying features a bright bleu colour
shifting to magenta with increasing viewing angle. The product is
calcinated at 500.degree. C. in air for 6 hours. X-ray diffraction
spectroscopy shows that the TiO.sub.2 is present in the rutile
modification and elemental analysis shows that the product contains
0.92% by weight Sn and 35.4% by weight of Ti.
Example 2
[0134] 4.5 g of glass flakes GF10 (Glassflake Ltd.), which have
been milled and sieved to obtain particles smaller than 100 microns
and larger than 20 microns, are mixed with 300 ml distilled water
in a closed reactor and heated at 75.degree. C. The pH is set to
1.2 and the suspension stirred at 350 rpm for 15 minutes. Then a
preparation comprising 9 g SnCl.sub.4.5H.sub.2O dissolved in 5 g
HCl (37%) and 100 g distilled water is added (0.8 ml/minutes)
during 15 minutes while stirring at 350 rpm. Once the addition of
the preparation is finished the suspension is stirred for 15
minutes and the pH is set to 1.8. Then a preparation comprising 34
g TiOCl.sub.2, 32 gHCl (37%) and 445 g distilled water is added at
0.8 ml/minutes during 1 hour while stirring.
[0135] After 1 hour a mixture of 15% of a preparation comprising 12
g of AlCl.sub.3.6H.sub.2O dissolved in 200 distilled water and 85%
of a preparation comprising 34 g TiOCl.sub.2, 32 g HCl (37%) and
445 g distilled water is added at the rate of 0.8 ml/minute during
4 hours at a constant pH of 1.8. Finally a preparation comprising
34 g TiOCl.sub.2, 32 g HCl (37%) and 445 g distilled water is added
at a rate of 0.8 ml/minute during 0.5 hours (pH=1.8). The powder
obtained after filtration and drying features a bright yellow
colour shifting to pearl grey with increasing viewing angle.
[0136] The product is calcinated at 500.degree. C. in air for 6
hours. X-ray diffraction spectroscopy shows that the TiO.sub.2 is
present in the rutile modification and elemental analysis shows
that the product contains 1.37 weight % of Sn, 11.6 weight % of Ti
and 1.58 weight % Al.
Example 3
[0137] 5 g GF10 (Glassflake Ltd.), which have been milled and
sieved to obtain particles smaller than 100 microns and larger than
20 microns, are dispersed in 55 g isopropanol and 7.5 g tetraethoxy
silane and the dispersion is heated at 60.degree. C. in a dosed
reactor. Then 6 g of distilled water and 2 g NH.sub.3 in 16 g
isopropanol are added during 3 hours. The glass flakes thus
obtained after filtration and drying are coated with a layer of
SiO.sub.2 having a thickness of about 30 nm.
* * * * *