Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Reexamination Certificate
1999-08-30
2002-06-04
Koslow, C. Melissa (Department: 1755)
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
C106S401000, C106S403000, C106S415000, C106S417000, C106S418000
Reexamination Certificate
active
06398862
ABSTRACT:
The invention relates to a non-dusting homogeneous pigment preparation notable in that it contains at least 40% by weight of one or more effect pigments.
Pigments in industrial processes are often employed not in the form of dry powders, since such powders form dust, which leads to increased requirements in terms of workplace safety. In addition, the incorporation of powders into plastics, basecoat systems, etc., is frequently observed to be accompanied by agglomeration of the pigment powder. Homogeneous distribution of the pigment in the respective matrix is in many cases difficult if not impossible to achieve.
Instead of the pigment powder, non-dusting pigment preparations are used. These are
free-flowing powders, pearl lustre pigments being coated with polymers, as are described, for example, in DE-C-2603211,
pigmented free-flowing powders with a low moisture content, as disclosed, for example, by DE-A-4139993, or
pigmented powders having a higher moisture content, the latter frequently being referred to as pastes owing to their fluid consistency.
Pastes are an industrial alternative to the dry or moistened powders provided they meet the following general conditions:
flowable consistency
minimal dilatancy
maximum pigment content
The components of the preparation/paste should be chosen such that the preparation is tailored to suit the other components of the respective coating system and, once incorporated, lends itself well to homogeneous distribution.
In addition to good compatibility with the other components of the coating system, pigment preparations are required to exhibit high stability; that is, they must not tend towards phase separation. This requirement is particularly important in the case of pigment preparations based on platelet-shaped pigments, since owing to their structure such pigments have a tendency to undergo caking on phase separation and are difficult to reagitate. For example, an aqueous pigment preparation obtained by forming an aqueous paste of a pearl lustre pigment powder frequently exhibits inadequate stability.
Aqueous pigment preparations, which have long been required for cosmetics, for example, are increasingly becoming of significance for other applications as well, such as for the production of waterborne coating materials, etc., on environmental grounds.
The preparations with pearl lustre pigments and metallic pigments that have been developed to date for use in coating systems, especially aqueous systems, with a pigment content >30% by weight frequently do not go far enough towards meeting the requirements described, especially insofar as they have a tendency towards shear thickening.
The object of the present invention was therefore to provide pigment preparations, especially in paste form, comprising at least 40% by weight of effect pigments, which can also be used to very good effect in aqueous coating systems, possess high stability, and at the same time feature a high level of compatibility with the other components of the coating system. Furthermore, the pigment preparation of the invention ought also to be suitable for producing dry preparations in the form, for example, of granules.
It has been found that this object. can be achieved by the provision of the pigment preparation of the invention. The invention therefore provides a non-dusting homogeneous pigment preparation which comprises
40-60% by weight of one or more effect pigments,
0.1-5% by weight of surface-active substances,
0.5-40% by weight of organic polymers,
1-40% by weight of an organic solvent or solvent mixture,
0-50% by weight of water and, if desired,
0-10% by weight of a pH regulator.
Depending on its moisture content, the preparation of the invention is a flowable paste which is highly suitable for producing dry preparations, e.g. granules, pellets, briquettes. The dry preparations produced from the pigment preparation of the invention are likewise provided by the invention.
Pearl lustre pigments used are pigments based on platelet-shaped, transparent or semitransparent substrates comprising, for example, sheet silicates, such as mica, synthetic mica, talc, sericite, kaolin, or comprising glass or other silicatic materials, which are coated with coloured or colourless metal oxides such as, for example, TiO
2
, Fe
2
O
3
, Fe
3
O
4
, SnO
2
, Cr
2
O
3
, ZnO, CuO, NiO and other metal oxides, alone or in a mixture, in one uniform layer or in successive layers. These pigments are, for example, from the German patents and patent applications 14 67 468, 19 59 998, 20 09 566, 22 14 454, 22 15 191, 22 44 298, 23 13 331, 25 22 572, 31 37 808, 31 37 809, 31 51 343, 31 51 354, 31 51 355, 32 11 602, 32 35 017 and P 38 42 330 and are obtainable commercially, for example under the brand name Iriodin® from Merck KGaA, Darmstadt, BRD. Particularly preferred pigment preparations comprise TiO
2
/mica, Fe
2
O
3
/mica and/or TiO
2
/Fe
2
O
3
mica pigments.
Suitable metallic pigments are all of the plateletshaped substrates known to the skilled worker, examples being aluminium plates or metal oxide-coated aluminium plates, as marketed, for example, by Eckart-Werke, Fürth.
The pigment preparations of the invention can comprise one or more effect pigments. In many cases, it is possible by using at least two different pearl lustre pigments to obtain special colour effects and lustre effects. The pigment preparation may also be a mix of pearl lustre pigment and metallic pigment. In that case the ratio is preferably from 10:1, especially 1:1. Preferred pigment preparations comprise one or more pearl lustre pigments.
The pigment preparation of the invention comprises preferably 40-60% by weight of effect pigments, in particular 45-60% by weight. Very particular preference is given to pigment preparations containing more than 50% by weight of effect pigments.
Suitable surface-active substances are, in particular, those which contain a hydrophobic molecular side chain, such as alkylsilanes, for example, which may also include a further functional group, unsaturated or saturated fatty acids, or fluorosurfactants. Particular preference is given to the use as surface-active substances of silane compounds of the formula (C
n
H
2n+1
)Si(OC
m
H
2m+1
)
3
, in which n is 1-30 and m is 1-10. Examples of suitable silane compounds are nhexyldecyltriethoxysilane and n-octyldecyltriethoxysilane (Si 116 and Si 118, respectively, from Degussa AG, Frankfurt, FRG) and the corresponding fluoroalkylsilanes.
Further surface-active substances employed are the saturated and unsaturated fatty acids, such as caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, and fatty acid mixtures.
Appropriate fluoro surfactants consist of a relatively long perfluorinated or partially fluorinated alkyl chain and a hydrophilic or organophilic head group, such as a polyoxyethylene, carboxyl or sulfone group, for example. They are cationic, nonionic or anionic in construction. Use is made in particular of fluoro surfactants which are marketed under the tradenames FLUORAD FC430 and FC431 (from 3M) and Borchigol FT448 (from Borchers, Dusseldorf, FRG).
The pigment preparation preferably comprises a silane, a surfactant or a fatty acid. The surface-active reagent can also comprise a mixture of silane, fatty acids and/or surfactants. The proportion of all compounds in the preparation should, however, not exceed 5% by weight, preferably 2% by weight.
The pigment preparations contain from 0.1 to 5% by weight, preferably from 0.2 to 3% by weight and, in particular, from 0.5 to 2% by weight of surface-active substances.
As a third-mandatory component, the pigment preparation of the invention contains from 0.5 to 40% by weight, preferably from 1 to 15% by weight and, in particular, from 2 to 10% by weight of an organic polymer or polymer mixture.
Suitable organic polymers are thickeners, dispersants and/or binder resins as commonly added to paints and coatings and as listed, for example, in Karsten, Lackrohstofftabellen, 8
th
edition 1987. Suitable binders
Hechler Wolfgang
Herget Gerhard
Husseini Brigitte
Koslow C. Melissa
Merck Patent Gesellschaft Mit Beschraenkter Haftung
Millen White Zelano & Branigan P.C.
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