CA1201255A

CA1201255A - Dark brown pigments of pseudobrookite structure

Info

Publication number: CA1201255A
Application number: CA000433167A
Authority: CA
Inventors: Richard A. Eppler
Original assignee: Mobay Corp
Current assignee: Bayer Corp
Priority date: 1982-09-22
Filing date: 1983-07-26
Publication date: 1986-03-04
Also published as: DE3332689A1; IT8348993A0

Abstract

DARK BROWN PIGMENTS OF PSEUDOBROOKITE STRUCTURE

ABSTRACT OF THE DISCLOSURE
Dark brown inorganic pigment materials which are characterized by high tinctorial strengths, excellent color and thermal stability, and very high opacity of pseudobrookite structure are produced by cocalcining compounds of iron and manganese with compounds of titanium and/or tin, and/or silicon.

Description

.

2~iS
Mo-2418 Pemco-009 BACKGROUND OF THE INVENTXON
The present invention rela-tes to inorganic dark brown pigments of pseudobrookite structure.
Pseudobrookite is a solid material of varying composition in which the unit cell is an orthorhombic 5 arrangement of 20 anions with 12 cations distributed in interstices between the anions. These materials may be represented by the general formula:
X2 Yn 2n+3 When n equals 1, the material is said to be stoichiometric. actual pseudobrookite materials, however, may deviate to some extent from stoichiometric composition. In pseudobrookite, the X ions are primarily trivalent (small amoun-ts of divalent ions may also be present) and the Y iOIlS are tetravalent. In 15 these materials, cations are present in the pseudobrookite struc-ture in octahedral coordination.
The starting materials which may be potentially useful in developing pseudobrookite are those for which the ionic radius is greater than 0.6 20 Angstroms but less than 1.0 Angstroms. Thus, ions such as iron, zinc, magnesium, nickel, copper, cohalt, manganese, titanium, tin, silicon, and vanadium may be appropriate.
Pigments having a pseudobrookite structure 25 have not been generally described or discussed in the literature. The specific compound Fe2TiO5 is, however, discussed in some detail in the scientific literature (for example, see the book, "The ~lajor Ternary Structural Families," by 0. Muller and R. Roy, 30 particularly page 232).

Pemco 009 ;~''' SUMMARY OF THE INVENT ION
It is an object of the present invention to provide an inorganic dark brown pigment.
It is also an object of the present invention 5 to provide a dark brown pigment with a pseudobrookite structure having high tinctorial strength, very high opacity, and excellent color and thermal stability.
These and other objects which will be appaxent to those skilled in the art are accomplished by 10 calcining a mixture of raw materials which mixture yields a calcination product corresponding to the general formula:
X2 Y 2n+3 in which X, Y, and n are as defined below.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to an inorganic dark brown pigment oE pseudobrookite structure haviny the general formula:
X2 Yn 2n~3 20 wherein n is a number from 0.4 to 2.0 and preferably from 0.9 to 1.1;
X represents a trivalent and/or divalent ion selected from the group consisting of 0.6 to 1.9 mols of iron, 25 0.1 to 1.4 mols of manganese, 0.0 to 0.25 mols of cobalt, 0.0 to 0.25 mols of zinc, 0.0 to 0.25 mols of nickel, 0.0 to 0.4 mols of copper, 0.0 to 0.25 mols oE
magnesium, and mixtures thereof, the total amount of said trivalent and/or divalent ions being 2.0 mols; and 30 Y represents a tetravalent ion selected from the group consisting of titanium, tin, silicon, and mixtures thereof. If desired, up to 5~ of the total mols of tetravalent ion can be vanadium.
Pemco 009 -In the most preferred embodiment, X represents a trlvalent ion selected from the group consisting of 1.3 to 1.8 mols of iron and 0.2 to 0.7 mols of manganese end Y represents titanium.
When the concentration of iron is less than 0.6 mols, the color is blaek. When the iron concentration exceeds 1.9 mols, the tinctorial strength is inadequate. Reverse effects are noted for manganese. That is, when the concentration ox 10 manganese exceeds 1.4 mols, the color is black rather than brown, while use of less than 0.1 mols of manganese results in a medium brown color rather than a dark brown. Up to 0.25 mols of magnesium or zinc may replaee iron but when the coneentration of either 15 magnesium or zinc exeeeds 0.25 mols, the product pigment is a medium brown. The total concentration of niekel and cobalt should be held to less than 0.25 mols and the eoncentration ox copper held to less than 0.4 mols to prevent a change of color.
Titanium, tin, silieon, or a eombination thereof ean be used for the tetravalent ion. The elarity of eolor when silicon is used is, however, inferior to that obtained with the other two ionsO
Eeonomie considerations make titanium the most 25 preferred alternative.
Considerable deviation from the pseudobrookite stoiehiometry can be tolerated in the system of the present invention. Wevertheless, when the value of "n"
is less than 0.4, the color is blaek rather than 30 brown. When the value of "n" exceeds 2.0, the tinctorial streng-th is greatly redueed due to the presenee of substantial rutile in the pigment which Pemco 009

3~.~55i

- 4 rutile structure material results in a medium brown color.
The piyments of the present invention Jay be prepared by weighing out appropriate arnounts of

5 conventional ceramic grade oxides and/or carbonates and carefully blending and passing these materials through a hammer mill to break up any agglomerates. These mixtures may then be calcined at temperatures of from 1500 to 2000F (816 to 1093C)~ Calcination fox 10 three to six hours at peak temperature and total cycles of 18 to 24 hours are preferred.
After calcining, it is generally necessary to mill the pigments until there is no residue upon a 325-mesh screen.
To Eurther illustrate this inven-tion, the following examples are presented.
EXAMPLES
The pigments oE the present invention were evaluated Eor their color properties by dispersing -them 20 in a paint medium. The paints were made by mixing 10.0 grams of the pigment of the present invention with 14.0 grams of soya oil alkyd resin, 16.5 grams of mineral spirits, 2.4 grams of naphtha, and 0.13 grams of driers. The mixture was then shaken on a paint shaXer 25 for 30 minutes with 30 grams of beads. The paint was then strained and 0.3 cc of additional driers were added. The paint was then drawn down with a 0.006 inch Bird applicator on a Laneta card that was half white and half black. The drawdown was allowed to air dry 30 for at least 24 hours. The fineness of the pigment was evaluated by a drawdown of the Hegman gage (see ASTM
test method ~1210 79). The color proper-ties were then Pemco O 0 9 ~2~

measured on a Diano/Hardy visible spectrophotometer, and are reported in terms of the reflectance Rd and the color parameters "a" and "b". (For a description of those parameters, see I. B. Judd ancl G. Wyszecki, 5 "Color in Business, Science and Industry", Wiley, New York, 1963, pO 296.) 1,331 grams ox ferric hydroxide, 724 grams of anatase, and 444 grams of manganese carbonate were lO weighed out, blended, and passed through a hammer mill. The mixture was then calcined at 1700F for three hours. The resulting very dark brown pigment was then flllid energy milled until there was no residue on a 325-mesh screen. The resulting pigment had -the 15 formula:
Fel 6MnO . 4TiO5 When placed in a paint as descrihed previously, a ~legman rearing of 7.5 was obtained. The paint was a dark brown color which had color readings 20 over a white background of:
Rd 5.3%
a = 2.1%
b = 2.1%
The pigment was fully opaque so that the color 25 properties over a black background were substantially the same as those over a white background.

-117.5 grams of ferric hydroxide, 73.1 grams oE
anatase, 44.8 grams of manganese carbonate, and 14.5 30 grams of black copper oxide were weighed out, blen-led, and passed through a hammer mill. They were then calcined at 1900F for three hours. The resulting dark Pemco 009 l 5 brown pigment was milled in water until there was no residue on a 325-mesh screen. The resulting pigment had the formula:
Fel 4Cu0 2r~no.4TiO5 r~hen incorporated in a paint vehicle as described above, the Hegman reading was 7.5 and the color properties over a white background were:
Rd = 5.2%
a = 1.4 b = 2.1~
The pigment was fully opaque so tha-t the color properties over a black background were substantially the same as those over a white background.
EXAMPT~S 3-12 Each of the formulations given in rrable 1 was made by weighing out the raw materials, blending those raw materials and passing the blend through a hammer mill. Each blend was then Eired according to the schedules given in Table 1. After iring, each oE the 20 calcined materials was milled in water until there was no residue upon a 325-mesh screen. The formula of thy resulting pigment in each case is given in Table 2.
The pigments were then individually added to the paint formulation described above in order to obtain a Hegntan 25 reading and evaluation of the color properties over both white and black backgrounds. In each case, the readings over the black background were equivalent to those over the white background because the pigments were fully opaque. The results are given in Table 2.

Pemco 009 f o f o . . . o So f or f I I
r~l I_ f r~r~) o en on o I I I o.~:
o r-f I:4 f rf) o f r r~l I I I o,s:
o o on f It o or Hot .
o h Us f f I I I o Us m f r~l cr f h r~l I I 1` o,~
l f I f f rr l 1:4 f Ln r~l o o l . . . . o h Ill f I 0,~
I_ rn En 1- ro r~l rs~ l r~J o . . . o h 1-- f I 0,~
r~l l rn ~D~ r h , I_ , . o h r- f I 1 0,5:
rn ,I f rJ~ O
o l O h o rho, f I`
or I` o f f o . . . o h r~l or I I I O I:
r~1-- rJ~
f r~7 a) a us Q~ f r f O O O O
tdO o rd f O I) h X O

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White Background Example Pigment Formula Hegman Reading Rd a b 1.8 0.2 5 6.6 4.2 5.7 4 FeMnTiO5 8 5.0 1.0 1.7 Fel 4Co 2Mn0 4TiO5 7.5 5.3 2.1 3.3

6 Fel 6ZnO 2Mno.2Ti5 ~-3 4.1 5.4

7 Fel 2Co0 2Zno 2Mn0-4Ti5 5-4 1.9 2.4

8 Fel 4Mgo 2Mno.4T 5 8 5.9 2.3 4.6 g Fel 6Mn0 4Tio.5O4 8 5.0 1.9 2.8 Fel 6Mno.4Ti2 7 5.8 1.9 3.1 11 Fel 3Mno.7Ti5 5.2 1.8 2.8 12 1.4ZnO.2~no.4TiO5 7.5 6.7 4.0 5.7 Pemco 009

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An inorganic dark brown pigment of pseudobrookite structure having the general formula:
X2 Yn O2n+3 wherein n is a number from 0.4 to 2.0, X represents a trivalent or divalent ion selected from the group consisting of 0.6 to 1.9 mols of iron, 0.1 to 1.4 mols of manganese, 0.0 to 0.25 mols of cobalt, 0.0 to 0.25 mols of zinc, 0.0 to 0.25 mols of nickel, 0.0 to 0.4 mols of copper, 0.0 to 0.25 mols of magnesium and mixtures thereof provided that the total amount of said trivalent and divalent ions is 2.0 mols and Y is a tetravalent ion selected from the group consisting of titanium, tin, silicon, and mixtures thereof.

2. The pigment of Claim 1 wherein n is a number of from 0.9 to 1.1.

3. The pigment of Claim 1 wherein X is a trivalent ion selected from the group consisting of 1.3 to 1.8 mols of iron and 0.2 to 0.7 mols of manganese.

4. The pigment of Claim 1 wherein Y is titanium.

5. The pigment of Claim 4 wherein X is a trivalent ion selected from the group consisting of 1.3 to 1.8 mols of iron and 0.2 to 0.7 mols of manganese.

6. The pigment of Claim 5 wherein n is a number of from 0.9 to 1.1.