AU622690B2

AU622690B2 - Lamellar colour lustre pigments

Info

Publication number: AU622690B2
Application number: AU38207/89A
Authority: AU
Inventors: Klaus-Dieter Dr. Franz; Constanze Dr. Prengel
Original assignee: Merck Patent GmbH
Current assignee: Merck Patent GmbH
Priority date: 1988-07-21
Filing date: 1989-07-18
Publication date: 1992-04-16
Anticipated expiration: 2009-07-18
Also published as: JPH0269573A; AU3820789A; BR8903564A; DE3824809A1; DE58903156D1; EP0354374B1; KR900001800A; FI893506A0; FI893506A; EP0354374A1

Description

b: Our Ref: 280290 622690

AUSTRALIA

Patents Act FORM COMPLETE SPECIFICATION

(ORIGINAL)

Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority: Related Art: I I Applicant(s): Merck Patent Gesellschaft Mit Beschrankter Haftung D-6100 Darmstadt FEDERAL REPUBLIC OF GERMANY C i c Address for Service: ARTHUR S. CAVE CO.

Patent Trade Mark Attornerys Level 10, 10 Barrack Street SYDNEY NSW 2000 the invention entitled "Lamellar colour lustre pigments".

Complete specification for The following statement is a full description of this invention, including the best method of performing it known to me:- 1 5020 la The invention relates to lamellar colour lustre pigments based on lamellar substrates coated with metal oxides.

It is known to coat lamellar substrates, such as, for example, glass, mica, graphite or metal lamellae, with a thin layer of one or more metal oxides. By virtue of the lamellar structure, the smooth, homogeneous surface and high refractive index of these metal oxides, this process affords pigments which have a high lustre and which, in addition to the intrinsic colour of the metal oxide applied, also exhibit in *a S some cases, depending on the layer thickness of the metal oxide layer, the interference colour of thin lamellae. A broad description of such lustre pigments is to be found, for U exarple, in US Patents 3,087,828 and 3,087,829 as well as in numerous other patents and patent applications.

Although numerous colour shades can be produced by means of the known processes, a need exists, both for applications in the cosmetics industry and in technology for pigments having interesting new colours and patterns of properties.

It has now been found, surprisingly, that it is possible to coat lamellar substrates with partly transparent coloured Slayers of oxide bronzes, pigments with interesting new proper-ies being obtained.

The invention therefore relates to lamellar colour lustre pigments based on lamellar substrates which have been coated j with metal oxides and which are characterized in that the metal oxide coating is composed, at least in part, of an oxide bronze of formula MxTO n in which M is at least one electropositive metal element of the I, II, III, IV main group or of the I, II, 0117g/Ar4P

I

r -2- III subgroup, T is at least one transition element of the IV, rT, VI, VII or VIII subgroup, x is a number between 0.01 and 1 and n is a number between 2 and 6.

The invention also relates to a process for the preparation of lamellar colour lustre pigments which is characterized in that a lamellar substrate is coated with an oxide bronze of the formula M TO in which M is at least one electropositive metal element of the I, II, III or IV main group or of the I, II or III subgroup, T is at least one transition element of the IV, V, VI, VII or VIII subgroup, x is a number between 0.01 and 1 and n is a number between 2 and 6.

I,

Oxide Lronzes per se have, in part, already been known a Ii t for a very long time. A review is to be found, for example, in Comprehensive Inorganic Chemistry, Volume 4, pages 541-605, Pergamon Press, 1973. A review covering oxide bronzes is also to be found in MTP Intern. Rev. Science, Inorganic Chemistry, i r 2nd Series, Volume 10 (1975) on pages 211-254. The composition of bronzes having a fairly complicated structure wh 4 ch can in each case contain several elements M and T as discussed on page 212 in the second paragraph. These bronzes are also stated to S be embraced by the formula indicated above. Hitherto, however, consideration has not yet been given to the application of such compounds in a thin layer to a support.

The pigments according to the invention display a wide variation of colours, which are determined firstly by the selection of the electropositive metal M and of the transition element T and secondly by the equivalent ratio x of the metal M.

Transition metals T which should be mentioned 0117g/AMP 2a particularly are tungsten, molybdenum, niobium, vanadium, titanium and manganese, of which tungsten and titanium are particularly preferred. Suitable electropositive metals M are, in principle, any metals which preferably occupy the formal oxidation stages 3 and 4 i.e. the elements of the I, II, III and IV main groups and of the I, Ii or III transition groups. Lithium, sodium, potassium, copper, silver, calcium, strontium, barium, zinc, cadmium, aluminium, indium, the lanthanides and NH 4 ;4 as a pseudo-alkali metal cation, are, j" however, employed particularly. Sodium, potassium, calcium and barium are particularly .I a e I I €j 0117g/AMP -3preferred.

The absorption colour of the oxide bronze is essentially determined by the proportion of the electropositive metal M. The colour can be varied within wide ranges by varying this proportion. The parameter x which indicates the proportion of M to T is variable in this regard, depending on the principal valency of the element M. For elements of the I main group and subgroup it is preferably between 0.1 and 1, for elements of the II main group and subgroup it is between 0.05 and 0.5, for elements of the III main group and subgroup it is between 0.01 and 0.3 and for elements of the IV main group it is between 0.01 and 0.2.

4 These oxide bronzes are applied in accordance with the invention to a lamellar substrate. Suitable 4 4 substrates are, in principle, any solid, heat-resistant materials which are available in the form of thin lamellae, i.e. preferably have, at a thickness of about 0.1-1 am, an extension in the two other dimensions of 20 about 5-200 pm, in particular about 10-50 pm. Suitable examples are mica, glass, metals or lamellar crystals of iron oxides and mixed crystals thereof with, for example, aluminium, zinc or manganese.

Lamellar substrates which are also suitable are, however, those which are already coated with a layer of metal oxide, such as, for example, the mica flakes coated with metal oxide which are known as pearlescent pigments and which are described, for example, in the following patents: US Patents 3,087,828 and 3,087,829 and German Patents 2,214,545 and 2,522,572. Metal oxides mentioned therein particularly are titanium dioxide, zirconium dioxide, tin dioxide, iron oxide, chromium oxide, zinc oxide, silicon dioxide and aluminium oxide.

The oxide bronzes are applied to these substrates, as a rule, in proportions of about 0.1-200% by weight, relative to the starting material, preferably in a proportion of about 1-100%. The end products thus contain about 0.1-66%, preferably 1-50%, of the oxide bronzes. In particular, contents of about 5 to 35% by r -4weight are used.

The preparation of the oxide bronzes in the form of a thin layer on the lamellar substrates is based on the processes which are also known for the preparation of the oxide bronzes in a pure state, which are described in Comprehensive Inorganic Chemistry (see above) and in the literature quoted therein. Processes which are particularly advantageous are those in which the starting materials for the formation of the oxide bronzes are 1 0 deposited on the lamellar substrates and these materials are converted into the oxide bronzes at an elevated Stemperature.

Thus, for example, a salt of the formula 1mTO n can be reacted with an oxide of the formula T'O and a metal it being possible for or T4T'?T", or mixtures I of transition metal oxides TO. with oxides M2IO, MIIO, MIII03 Sor MIVO 2 or salts M1-TO. can be reduced at an elevated Stemperature of about 300-1,200'C, preferably about 400i 900°C, in a reducing gas atmosphere, for example an atmosphere of hydrogen, if appropriate mixed with an r inert gas, such as, for example, nitrogen. It is possible I to predetermine the factor x of the oxide bronze M.TOn in a simple manner by altering the relative proportions of the salt MmTOn or M oxide to the transition metal oxide

TO.

The precipitation of the oxide mixtures can be effected in this case simultaneously or successively in water or in organic phases diluted with water. In this regard it is, of course, also possible to employ several electropositive metals M or transition metal elements T jointly. In cases where the electropositive metal M does not form a sparingly soluble oxide or hydroxide, such as, for example, in the case of elements of the I and II main group, M can also be precipitated in the form of a sparingly soluble salt of a simple organic acid, for example from 1:1 mixtures of alcohol and water. Thus, for example, sodium can be precipitated as the oxalate or acetate, which decomposes in the subsequent calcination, the acid radical involved being volatilized with the r formation of gaseous reaction products.

The starting materials are precipitated by suspending the lamellar substrates, preferably in water or an organic solvent diluted with water, and, by adding the reagents at conditions of pH and temperature suitable for the precipitation, precipitation of the salts or oxides is effected, these compounds being deposited on the lamellar substrates distributed in the suspension.

The conditions necessary for this in each case are known to those skilled in the art and can be obtained from the relevant textbooks.

After the starting materials have been precipitated, the pigments are preferably removed, washed, if 1 appropriate, and then calcined in a reducing gas atmosphere for about 0.5 to about 3 hours. Hydrogen should be particularly mentioned as a reducing gas, but it is, however, also possible to employ other gases, such as, for example, ammonia or methane. As a rule the reducing gases are employed as a mixture with an inert gps such as, for example, nitrogen.

cc I After the pigments have been cooled they have a C C stable composition and they can be employed for the customary purposes, such as, for example, for pigmenting plastics, lacquers, paints and cosmetics. Owing to the known properties of oxide bronzes as electrical conductors or semi-conductors, numerous possibilities present themselves for special applications in which such properties can be employed to advantage.

Example 1 250 ml of an aqueous solution of 28 g (0.085 mol) of Na 2

WO

4 X 2 H 2 0 and 5 g (0.125 mol) of sodium hydroxide are metered, in the course of 2 hours, into a suspension of 50 g of Iriodin 103 (a silver-white pearlescent pigment made by E. Merck, Darmstadt, consisting of mica of a particle size of 10-50 am coated with titanium dioxide) in 2 1 of water which has been heated to and adjusted to a pH value of 1.5 with 10% hydrochloric acid, the pH being kept constant by the simultaneous addition of aqueous hydrochloric acid. Stirring is then -6continued for about 15 minutes at the boil and for about hours with slow cooling. The pigment coated with (W0 3 in this manner is separated off and washed.

g of a pigment coated in this manner with 22.5% of (W0 3 )x are suspended in 25 ml of water, and a solution of 0.33 g (2.46 mmol) of sodium oxalate is added at a pH of 4.6. The pH is then adjusted to a value of 6.0 with 1% sodium hydroxide solution, and 50 ml of ethanol are added in order to precipitate the sodium oxalate. After stirring for a further half hour the pigment is separated off, washed with water and dried at about 100 0

C.

The pigment coated in this manner with (WO 3 )x and sodium oxalate is exposed to a hydrogen/nitrogen mixture in a ratio by volume of 2.7:1 for half an hour at a S' 15 temperature of 600 0 C and is then allowed to cool in a stream of hydrogen/nitrogen. A bright, steel-blue grey piment having a high hiding power and a coating of formal composition NaWO 3 is obtained.

Example la The procedure is analogous to that of Example 1, cc' q but reduction is carried out at a temperature of 900 0

C.

A yellowish grey pigment of high hiding power is obtained.

Example 2 The procedure is analogous to that of Example 1, but 0.22 g (1.64 mmol) instead of 0.33 g of sodium S oxalate is used for coating. A pigment of metallic lustre which has a steel-blue grey colour and a coating of formal composition Nao 0 7 W0 3 is obtained.

Example 2a SThe procedure is analogous to that of Example 2, but reduction is carried out at a temperature of 900 0

C.

A dark grey pigment of metallic lustre and high hiding power is obtained.

Example 3 The procedure is analogous to that of Example 1, but 0.16 g (1.19 mmol) instead of 0.33 g of sodium oxalate is used for coating. A pigment of metallic lustre and a steel-blue grey colour, having a coating of formal n 7 composition Naa 0

.WO

3 is obtained.

Example 3a The procedure is analogous to that of Example 3, but reduction is carried out at a temperature of 900°C.

A dark grey pigment of metallic lustre and high hiding power is obtained.

Example 4 The procedure is analogous to that of Example 1, but 0.13 g (0.9 mmol) instead of 0.33 g of sodium oxalate is used for coating. A pigment of metallic lustre and a steel-blue grey colour, having a coating of formal 1 composition Na 0 4 W0 3 is obtained.

K Example 4a The procedure is analogous to that of Example 4, but reduction is carried out at a temperature of 900 0

C.

A dark grey pigment of metallic lustre and high hiding power is obtained.

Example 100 ml of 0.15-molar aqueous solution of sodium tungstate is added to a suspension of 20 g of mica, of Sparticle size 10-50 pm, in 300 ml of water, and the pH is adjusted to a value of 4.5 with 10% hydrochloric acid.

100 ml of a 1.5-molar solution of sodium tungstate and 100 ml of a 1.5-molar solution of calcium chloride are then metered in simultaneously, and the mixture is then heated to 85 0 C and stirred for a further 0.5 hour. The pigment coated with calcium tungstate is separated off, washed, dried and exposed to a hydrogen/nitrogen atmosphere for half an hour at 700°C. After cooling for half j 30 an hour in the gas stream, a pale grey, transparent pigment is obtained.

Example 6 The procedure is analogous to that of Example but 200 ml of the 1.5-molar sodium tungstate solution and 200 ml of the 1.5-molar calcium chloride solution are used. A transparent pigment having a blue-black colour is obtained.

Example 7 The procedure is analogous to that of Example 1 but 40C 400 ml ~I used.

colour Exampl 1> 8 ml of the 1.5-molar sodium tungstate solution and of the 1.5-molar calcium chloride solution are A transparent pigment having a blue-violet/black is obtained.

e 8 ii; 11 ,r r,

I

r. rr i r r The procedure is analogous to that of Example but Iriodin 225 (a mica pigment coated with titanium dioxide, having a blue interference colour and a particle size of 10-50 pm, made by E. Merck, Darmstadt) is employed as the substrate. A pigment of high lustre and grey-blue colour is obtained.

Example 8a The procedure is analogous to that of Example 8, but reduction is carried out at 600°C. A pigment of high '15 lustre and pale grey/blue colour is obtained.

Example 8b The procedure is analogous to that of Example 8, but reduction is carried out at 800°C. A pigment of high lustre and cornflower-blue colour is obtained.

Example 8c The procedure is analogous to that of Example 8, but reduction is carried out at 900"C. A pigment of high lustre and black-violet colour is obtained.

Example 9 15 g of a mica pigment coated with TiO 2 and containing, in the TiO 2 layer, small amounts of sodium ions (Timiron Super Blue made by Rona Pearl, USA) are exposed to a hydrogen/nitrogen stream (H 2

:N

2 1:2.7) in a quartz tube for 30 minutes at 800°C. A lustrous pigment of pale grey surface colour and cornflower-blue interference colour is obtained.

Example A solution of 9.41 g (0.105 mol) of oxalic acid in 250 ml of ethanol and a solution of 13.8 ml of 32% aqueous NaOH in 250 ml of ethanol are added dropwise, simultaneously, to a suspension of 50 g of Timiron® Super Blue in 1,000 ml of ethanol in the course of 2 hours at room temperature. After the mixture has been stirred for a further 15 minutes, a solution of 33 ml of triethanol- 11.

I-

r WNO C 9 amine titanate in 250 ml of ethanol and a solution of 23 ml of 32% NaOH in 250 ml of ethanol are added simultaneously, in the course of 2 hours. After stirring for a further 30 minutes the pigment is separated off, washed with ethanol and dried at 100 0 C for 16 hours.

A grey-violet, highly lustrous pigment is obtained by reduction for half an hour at 800 0 C in an

H

2

/N

2 stream (H 2

:N

2 1:2.7).

Example 11 The procedure is analogous to that of Example A black-violet, highly lustrous pigment is obtained by reduction for half an hour at 900 0

C.

Set Example 12 S, A solution of 3.76 g (0.042 mol) of oxalic acid 15 in 100 ml of ethanol and also a solution of 13 ml of 32% NaOH in 100 ml of ethanol are metered, in the course of c tr 50 minutes, into a suspension of 50 g of a mica pigment coated with TiO 2 (Iriodin® 100 Silberperl made by E. Merck, Darmstadt) in 1,000 ml of ethanol. After stirring for a further 30 minutes, the pigment is separat',ed off, washed with ethanol and dried overnight at 100"C.

A blue-grey, lustrous pigment is obtained by reduction for 30 minutes at 800 0 C in an H 2

/N

2 stream.

Example 13 The procedure is analogous to that of Example 12.

A dove-blue lustrous pigment is obtained by reduction at 900 0

C.

Example 14 A solution of 9.45 g (0.105 mol) of oxalic acid in 150 ml of water and a solution of 11.02 g of CaCl 2 .2 HzO (0.075 mol) in 150 ml of water are added dropwise, in the course of 75 minutes and at room temperature, to a suspension of 50 g of Iriodin® 100 in 1,000 ml of water. After stirring for a further minutes, 160 ml of a 0.019-molar aqueous solution of TiC1 4 are added in the course of 50 minutes, the pH being kept at a value of 2 by simultaneously adding 10% aqueous NaOH solution. After stirring for a further 15 minutes, 10 the pigment is separated off, washed with water and dried overnight at 100 0 C. A silver-grey lustrous pigment is obtained by reduction in an H 2

/N

2 stream (H 2 5.2:1) for 30 minutes at 900 0

C.

Example A solution of 9.38 g (0.104 mol) of oxalic acid in 150 ml of water and a solution of 15.13 g (0.074 mol) of MgCl 2 .6 H 2 0 in 150 ml of water are added dropwise, j simultaneously and in the course of 75 minutes, to a suspension of 50 g of Iriodin® 100 in 1,000 ml of water.

K After stirring for a further 15 minutes, 160 ml of a 0.019-molar aqueous solution of TiC14 are added in the Scourse of 50 minutes, the pH being kept constant at a value of 2 by simultaneously metering in 10% sodium hydroxide solution. After stirring for a further I minutes, the pigment is separated off, washed with water Sand dried overnight at 100 0

C.

A silver-grey, highly lustrous pigment is obtained by reduction in an H,/N 2 stream (H 2

:N

2 5.2:1) for 30 minutes at 900°C.

Example 16 A solution of 1.88 g (0.021 mol) of oxalic acid in 100 ml of ethanol and a solution of 6.37 ml of 32% t aqueous NaOH in 100 ml of ethanol are added dropwise, simultaneously and in the course of 50 minut-s, to a suspension of 50 g of Iriodin® 103 (silver-white rutile/mica pigment made by E. Merck, Darmstadt) in 1,000 ml of ethano', stirring is continued for a further minutes and the pigment is then separated off, washed with ethanol and dried overnight at 100"C.

A silver-grey, lustrous pigment is obtained by reducing the pigment in an H,/N 2 stream (H 2

:N

2 1:2.7) for minutes at 700 0

C.

Example 17 The procedure is analogous to that of Example 16, but is carried out at 850 C. A dark silver-grey, lustrous pigment is obtained.

Example 18 ml of a 1.6-molar solution of n-butyllithium Z~ C IIICIY1- i 11 11 in n-hexane were added dropwise, in the course of minutes, at room temperature and under an inert gas atmosphere, to a suspension of 10 g of Iriodin 225 in ml of anhydrous toluene. The pigment suspension reacts with the evolution of heat and gas and with a blue coloration. When the reaction is complete, unreacted nbutyllithium is destroyed by adding 20 ml of methanol dissolved in 20 ml of toluene. The pigment is then filtered off, washed with 100 ml of methanol and then with 500 ml of completely demineralized water and dried at 100"C for 2 hours. A blue-grey pigment is obtained in this way.

Ii

Claims

2. Lamellar colour lustre pigments according to Claim 1, characterized in that the oxide bronze is present in a proportion of 0.1 to 200% by weight, relative to the lamellar substrate.
3. Lamellar colour lustre pigments according to Claim 1, characterized in that M is one or more elements belonging to the group consisting of lithium, sodium, potassium, copper, silver, calcium, strontium, barium, zinc, cadmium, aluminium, indium, lanthanum and the rare-earth metals and also the pseudo-alkali metal cation NH 4
4. Lamellar colour lustre pigments according to Claim 1, characterized in that the value x is between 0.1 and 1 for elements of the I main group and subgroup, between 0.05 and for elements of the II main group and subgroup, between 0.01 and 0.3 for elements of the III main group and subgroup and between 0.01 and 0.2 for the elements of the IV main group. Lamellar colour lustre pigments according to Claim 1, characterized in that T is one or more elements of titanium, vanadium, niobium, molybdenum, tungsten or manganese.
6. Process for the preparation of lamellar colour lustre pigments, characterized in that a lamellar substrate is coated with starting materials for the fcrmation of an oxide bronze and that these materials are converted into the oxide bronze at an elevated temperature of 300-1,200 0 C, the oxide bronze being of the formula M TO in which M is an x n electro-positive metal element of the I, II, III or IV main CI 1-0269p:mmb -13 group or subgroup, T is a transition element, x is a number between 0.01 and 1 and n is a number between 2 and 6.
7. Process according to Claim 6, characterized in that in a suspension of a lamellar substrate a transition metal oxide TOn and an oxide, hydroxide or salt of the electro- positive metal M are deposited simultaneously or successively on the lamellar substrate, and the substrate coated in this way is separated off, optionally washed and dried and then exposed to a reducing gas stream at a temperature of 300-1,200 0 C.
8. Lamellar colour lustre pigments substantially as herein described with reference to the examples. I DATED this 16th day of October, 1991. ij i* MERCK PATENT GmbH j By Its Patent Attorneys ARTHUR S. CAVE CO. 1 S. S C t C I A. "^Ssli