Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Particulate matter
Reexamination Certificate
1998-01-09
2001-03-20
Thibodeau, Paul (Department: 1773)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Particulate matter
C106S410000, C106S411000, C106S493000, C106S494000, C106S499000
Reexamination Certificate
active
06203909
ABSTRACT:
The present invention relates to a composite pigment consisting of a substrate and a colourant.
This invention also relates to a process for the preparation of the composite pigments according to this invention, to their use for mass colouring high molecular weight organic material, for the preparation of paint systems, printing inks and inks, as well as to mass-coloured high molecular weight organic material.
In Langmuir 1995, 11, p. 2713-2718, Cooper et al. describe dye systems which are composed of several layers, where layers of congo red anions or copper phthalocyanine anions and of cationic polypeptides or copper phthalocyanine cations are alternately applied to a positively charged glass layer. Disadvantages are the elaborate method of preparation involving the layer-wise application of the differently charged compounds and also the restriction of the substances used to ionic dyes or dyes which can be correspondingly modified. In addition, the colour intensity is impaired by the intermediate layers between the monomolecular layers of the desired dye.
EP-A 472 990 describes substrate-layer systems where the uni- or multilayered layer elements consist of organic materials which are applied to the modified substrates by salt formation. Organic materials used are either monomeric substances carrying two ionic or ionisable functional groups having a charge rotating in the same direction, or polymers carrying a multitude of ionic or ionisable functional groups having a charge rotating in the same direction (polyelectrolytes). These systems have the disadvantage that (a) only (soluble) dyes can be used and that (b) these dyes can only be covalently bound to the organic materials.
DE-A 42 25 357 describes luster pigments based on substrates in platelet form and on chemically modified dyes carrying at least one basic functional group. Precondition for this process is the acid-solubility of the modified dyes. The modified dye is applied to the substrate by precipitation by neutralising the acid to reduce the acid-solubility of the dye. This process has the disadvantage that (a) only acid-soluble dyes can be used; (b) the acid must be neutralised (disposal problem and additional processing step); (c) the dye must carry a basic functional group; (d) the particle size cannot be controlled because of the precipitation; (e) the amount of adsorbed colourant in the substrate is not concentrated enough for some fields of application.
DE-A 42 25 031 describes the preparation of luster pigments carried out by applying an organic pigment, which can be dissolved undecomposed in a solvent, by precipitation to an inorganic substrate, a second solvent being added which is able to reduce the solubility of the organic pigment in the first solvent. The disadvantages of this process are (a) the use of solvent-soluble organic pigments; (b) the use of at least two solvents (costs, additional processing step for their separation, large volumina); (c) the lack of control of the particle size during precipitation; and (d) the concentration of adsorbed colourant in the substrate which is too low for some fields of application.
U.S. Pat. No. 5,037,475 describes the preparation of a coloured metallic pigment which is carried out by adsorbing in a first step a carboxylic acid group-carrying polymer to a metal pigment and then, in a second step, adsorbing a coloured organic pigment to the surface of the modified metal pigment obtained in the first step. The disadvantages of this process are (a) the restriction to COOH-group-carrying polymers; (b) the restriction to metallic pigments; (c) that the thickness of the polymer layer between modified metal pigment and organic pigment cannot be controlled; and (d) that the adhesion in some organic pigments does not suffice for commercial applications.
EP-A 278 633 discloses the preparation of coloured mica pigments which is carried out by precipitating a polymer carrying anionic groups with a polyvalent metal cation in the presence of mica and an organic pigment. This process has the disadvantage of affording instead of a pure end product mixtures consisting of coloured mica pigments (mica, organic pigment and precipitated polymer), mica and precipitated polymer, organic pigment and precipitated polymer, and also precipitated polymer. Using this process, it is furthermore impossible to control the layer thickness of the polymer applied by precipitation between mica particles and organic pigment particles.
Accordingly, it is the object of this invention to provide a composite pigment which does not have the above disadvantages. In particular, a process is to be found which does not require a precipitant. In addition, possible aggregation of pigment particles and possible uncontrolled chemical reactions, such as polymerisation, should be prevented. The preparation process should furthermore be simple, the layer thickness of the colourant on the substrate, or on the layer material separating the substrate and the colourant, should be controllable, and the concentration of the colourant in the composite pigment should be sufficiently high. Finally, a process should be provided in which colourants, in particular dyes, can be used without chemical modification, i.e. without binding them covalently to another material.
Accordingly, a composite pigment has been found which consists of a colourant and a substrate, using a substrate (S) and a colourant (C), which are each coated with ions or ionisable compounds having a charge rotating in the same direction, and, if desired, additional ions or ionisable compounds having a charge rotating in the same direction as layer material (L), wherein either (I) the sign of the charge of the coating of S, or the sign of the charge of the coating of S and of the charge of L, which is the same, is opposite to that of the charge of the coating of C, or (II) the sign of the charges of the coatings of S and C is the same and is opposite to that of the sign of the charge of L.
Furthermore, there has been found a process for the preparation of the novel composite pigments, their use for the preparation of pigmented material, in particular for pigmenting high molecular weight organic materials, in particular biopolymers, plastic materials, glasses, ceramic products, for formulations of decorative cosmetics, for the preparation of paint systems, preferably automotive lacquers, printing inks, inks and dispersion paints, as well as pigmented material comprising the novel composite pigments.
The coated substrate and/or coated colourant can also be replaced with an uncoated substrate and/or colourant by coating these in a first step and then preparing the novel composite pigments with the pigment components coated in this manner.
According to this invention, a substrate is used which is coated with at least one compound selected from the group consisting of
(a) a polymer carrying ionic or ionisable functional groups,
(b) an inorganic polyelectrolyte,
(c) a silane, in particular if the modified substrate contains silicium,
(d) a phosphonate and/or phosphate ester carrying ionic or ionisable functional groups, in particular if the modified substrate contains aluminium and/or titanium.
Substrates used for the novel composite pigment can be silicates, such as naturally occuring and synthetic mica, e.g. biaxed mica and muscovites, in particular muscovite, phlogopite, biotite, talcum flakes and glass flakes, iron mica, metal pigments consisting of aluminium, zinc, iron, nickel, tin, copper and silver as well as their alloys, preferably aluminium, and mica coated with metal oxide.
The metal pigments can be used in the form of an uncoated or coated powder or paste. As coating materials it is possible to use metal oxides, preferably silicium dioxide or aluminium oxide, in a manner known per se.
The corresponding substrates are commonly known (see e.g. the documents mentioned at the outset) so that further details may be dispensed with here.
A preferred embodiment of this invention uses metal oxide-coated substrates, preferably those based on mica and alumini
Ahmed Sheeba
Ciba Specialty Chemicals Corporation
Crichton David R.
Mansfield Kevin T.
Thibodeau Paul
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