Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Reexamination Certificate
2000-06-19
2002-08-06
Bell, Mark L. (Department: 1755)
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
C106S436000, C106S443000
Reexamination Certificate
active
06428615
ABSTRACT:
DESCRIPTION
The present invention relates to novel pigment preparations including as essential blending components
A) an inorganic pigment from the group of the bismuth vanadate pigments and rutile pigments and
B) a phosphate.
It further relates to the production of these pigment preparations and to their use for coloring polymeric materials.
It further relates to coating compositions including a film-forming polymer, a pigment from the group of the bismuth vanadate pigments and rutile pigments and a phosphate as well as further ingredients customary for these coating compositions.
Bismuth vanadate pigments are well known. As well as pure BiVO
4
pigments, there are a number of BiVO
4
pigments in which some of the metal and/or oxygen atoms are replaced by other metals and/or nonmetals. These pigments are interesting nontoxic yellow pigments and are particularly useful for coloring paints and plastics. To improve their application properties such as thermostability, weatherfastness and chemical resistance, bismuth vanadate pigments are frequently provided with protective sheaths made of metal phosphates (U.S. Pat. No. 4,115,141, U.S. Pat. No. 5,123,965 and DE-A-198 40 156, which was unpublished at the priority date of the present invention, but also with protective sheaths made of metal oxides and/or metal fluorides. These protective sheaths are nonporous and continuous and are produced by precipitating the phosphates, oxides or hydroxides and fluorides from preferably aqueous solutions of soluble salts of the corresponding metals.
Such stabilizing coatings are also well known for rutile pigments (e.g. U.S. Pat. No. 3,946,134). A particularly important group of rutile pigments is the group of colored rutile mixed-phase pigments which are obtained through incorporation in the rutile crystal lattice of transition metals which form colored oxides.
EP-A-721 005 describes printing ink pigment preparations which are based on luster pigments and further include an alkali metal polyphosphate and also spherical particles. The additional components are used in order to reduce print-run stability problems typical of platelet-shaped pearl luster pigments.
Existing bismuth vanadate pigments and rutile pigments may give rise to problems on incorporation into varnishes. More particularly, when these pigments are incorporated into two-component coating systems, it is observed that the viscosity of the varnish increases very rapidly and that processing is possible only for a short period.
It is an object of the present invention to remedy these defects and to provide pigment preparations having advantageous application properties.
We have found that this object is achieved by pigment preparations including as essential blending components
A) an inorganic pigment from the group of the bismuth vanadate pigments and rutile pigments and
B) a phosphate.
The invention further provides a process for producing these pigment preparations, which comprises milling the as-synthesized crude pigment together with said phosphate.
The invention further provides for the use of the pigment preparations for coloring polymeric materials.
The invention additionally provides coating compositions including a film-forming polymer, a pigment from the group of the bismuth vanadate pigments and rutile pigments and a phosphate as well as further ingredients customary for these coating compositions.
Useful blending components (A) for pigment preparations according to the invention include all known bismuth vanadate pigments and rutile pigments. Reference is made by way of example to pigments known from the following publications: EP-A-074 049, 239 526, 430 888, 492 244, 551 637, 640 566, 758 670 and WO-A-92/11205 and also Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed., Vol. A20, 307-308 (1992).
It will be appreciated that the pigment preparations of the invention may also include mixtures of these pigments.
The phosphate component (B) may be in particular an inorganic phosphate, in which case preference is given to metal phosphates which are essentially insoluble in substantially neutral aqueous media, in particular in water.
All known phosphates are suitable, i.e., mono-, di-, poly- or metapolyphosphates, although orthophosphates (monophosphates) are particularly suitable. Orthophosphates may include further anions such as hydroxide and/or halide ions such as fluoride and chloride ions.
Preferred metals for metal phosphates are boron, aluminum, zinc or an alkaline earth metal such as magnesium, calcium, strontium or barium. Particular preference is given to calcium and aluminum. Mixed salts may also be present.
Examples of phosphates to be used according to the invention are: BPO
4
, AlPO
4
, Al
2
PO
4
(OH)
3
, Al
3
(PO
4
)
2
(OH,F)
3
, Zn
3
(PO
4
)
2
, Zn
2
P
2
O
7
, Mg
3
(PO
4
)
2
, Mg
2
P
2
O
7
, Ca
3
(PO
4
)
2
, Sr
3
(PO
4
)
2
, Ba
3
(PO
4
)
2
, Ca
5
(PO
4
)
3
OH, Ca
5
(PO
4
)
3
F, Ca
5
(PO
4
)
3
Cl, Ca
5
(PO
4
)
3
(OH,F,Cl), Na
n+2
P
n
O
3n+1
(n=2-10), Na
n
H
2
P
n
O
3n+1
(n=16-90), Na
n
P
n
O
3n
(n≧3). Calcium phosphates and aluminum phosphates are preferred, and Ca
5
(PO
4
)
3
OH and AlPO
4
are particularly preferred. Mixtures of these phosphates are also useful as component (B).
Pigment (A) and phosphate (B) are present in the pigment preparations of the invention as separate, distinct blending components in that the pigment particles have not been provided with a sheath of phosphate (B).
In general, pigment preparations according to the invention include from 50 to 99%, preferably from 55 to 99%, preferably from 70 to 97%, particularly preferably from 80 to 95%, by weight of pigment (A) and from 1 to 50%, preferably from 3 to 30%, particularly preferably from 5 to 20%, by weight of phosphate (B).
Pigment preparations according to the invention are advantageous to produce using the process of the invention by milling the as-synthesized crude pigment together with the phosphate.
Milling may take the form of wet milling or dry milling, wet milling being preferred.
The crude pigment may be used for example as moist filtercake or as pigment clinkers obtained from the calcination following the synthesis. The pigment, if desired, may already be coated with one of the stabilizing coatings mentioned, but the particle size and shape of the pigment is still to be finalized.
Wet milling is preferably carried out in an aqueous medium. However, suitable media also include organic solvents which may be protic or a protic, and also mixtures of these solvents with each or one another and/or with water. It is favorable to use the liquid used in the final wash of the crude pigment.
Examples of suitable protic organic solvents are monohydric aliphatic alcohols, especially C
1
-C
12
alcohols, and also polyhydric alcohols, especially C
2
-C
3
alkylene glycols, and ether alcohols, especially C
2
-C
3
alkylene glycol-C
1
-C
4
alkyl ethers. Specific examples are ethanol, propanol, diethylene glycol and ethylene glycol monobutyl ether.
Examples of suitable aprotic organic solvents are cyclic ethers such as tetrahydrofuran.
The pigment is customarily used in wet milling in the form of a from 10 to 60% strength by weight suspension of the pigment in the solvents mentioned.
Wet milling on an industrial scale may with advantage be effected in an unstirred ball mill or in a stirred ball mill, preferably operated at from 100 to 2000 rpm. Examples of suitable grinding media are glass beads, zirconia beads or sand grains, preferably from about 0.4 to 30 mm in diameter. Milling on a laboratory scale may be carried out, for example, in vibromills and shakers containing grinding media.
For dry milling, ball mills and jet mills are correspondingly suitable.
Milling is customarily carried on until the median pigment particle size (d
50
value) is within the range from about 0.4 to 2 &mgr;m, preferably from 0.5 to 1.5 &mgr;m. The phosphate particle size is advantageously also within these ranges. If appropriate, it is advisable to premill the phosphate. Its particle size should not be >5 &mgr;
Reisacher Hansulrich
Seeger Oliver
Bell Mark L.
Hailey Patricia L.
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