Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Reexamination Certificate
2000-09-14
2003-04-08
Green, Anthony J. (Department: 1755)
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
C106S031600, C106S031670, C106S031690, C106S031900, C106S415000, C106S416000, C106S418000, C106S439000, C106S445000, C106S446000, C106S447000, C106S457000, C106S487000, C106S490000, C106S491000, C106S499000, C106S501100, C106S504000, C428S403000, C428S404000, C428S407000, C524S437000, C524S442000, C524S447000, C524S449000
Reexamination Certificate
active
06544327
ABSTRACT:
The invention relates to a non-dusting homogeneous pigment preparation notable in that it comprises at least 40% by weight of one or more effect pigments, 0.5-60% by weight of an aldehyde or ketonic resin and 0.10-10% by weight of a redispersant, based on the pigment.
In industrial processes, pigments are seldom employed in the form of dry powders, since the latter produce dust, which leads to increased requirements in terms of workplace safety. In many cases, furthermore, when introducing powders into plastics, basecoat systems, etc., agglomeration of the pigment powder is observed. Homogeneous distribution of the pigment in the respective matrix is frequently difficult if not impossible to achieve.
Instead of the pigment powder, non-dusting pigment formulations are used. These formulations are
free-flowing powders, where pearl lustre pigments are coated with polymers, as are described, for example, in DE-C-2603211,
pigmented free-flowing powders having a low moisture content, as are known, for example, from DE-A-4139993,
pigmented powders having a relatively high moisture content, which owing to their flowable consistency are frequently referred to as pastes, or
dry preparations as precursors for printing inks, as are known, for example, from EP 0 803 552.
Pastes, and dry preparations prepared from them, are a technical 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 formulation is customized to suit the other components of the respective coating system and is readily homogeneously distributed following its introduction.
In addition to good compatibility with the other constituents 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. Pigments based on platelet-shaped substrates give rise to handling problems insofar as, owing to the size and density of the pigments, they readily settle and may then cake together to form a very firm sediment cake. This cake is generally difficult to reagitate. It is particularly so in connection with the storage of varnishes, paints and printing inks and their processing.
Thus numerous methods have been developed, inter alia, in order to solve the problem of the incorporation and handling of platelet-shaped pigments in coating compositions. Reagitation can be facilitated by treating the coating compositions with additives which alternatively bring about controlled flocculation (house of cards effect), pseudoplastic and/or thixotropic behaviour, or steric and/or electrostatic repulsion of the pigments. However, these additives may have an adverse effect on the quality of the coating. In particular, the brightness in the case of effect pigments, and the uniformity of the coating, may be impaired.
In addition, homogeneous, stable distribution of the redispersants in the pearl lustre pigment powder is difficult to achieve, and/or the redispersant loses some of its activity in the course of mixing.
The formulations with effect pigments that have been developed to date for use in coating systems, with a pigment content of >30% by weight, frequently do not go far enough towards meeting the requirements described, in particular in that they have a tendency towards agglomeration and shear thickening.
The object of the present invention was therefore to provide pigment preparations, in particular in the form of pastes and dry preparations, which can be used to very good effect in solvent-containing coating systems, possess high stability, are readily redispersed, 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 pellets, granules, etc.
Surprisingly 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% by weight of one or more effect pigments,
0.5-60% by weight of an aldehyde or ketonic resin,
0.10-10% by weight of a redispersing auxiliary, and, if desired,
40% by weight of an organic solvent or solvent mixture.
Depending on its moisture content, the preparation of the invention is a flowable paste or a moistened, free-flowing powder. Both paste and powder are high suited to the production of dry preparations, examples being granules, pellets, and briquettes. The dry preparations produced from the pigment formulation of the invention are likewise provided by the invention.
Effect pigments used are pigments based on platelet-shaped, transparent or semitransparent substrates comprising, for example, phyllosilicates, such as mica, synthetic mica, SiO
2
flakes, TiO
2
flakes, holographic pigments, talc, sericite, kaolin, or comprising glass or other silicatic materials which are coated with coloured or colourless metal oxides, such as TiO
2
, titanium suboxides, titanium oxynitrides, 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 (multilayer pigments). Pearl lustre pigments are known, 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, FRG. Particularly preferred pigment preparations comprise TiO
2
/mica, Fe
2
O
3
/mica and/or TiO
2
/Fe
2
O
3
mica pigments. The SiO
2
flakes can be coated, for example, as described in WO 93/08237 (wet-chemical coating) or DE-A 196 14 637 (CVD process).
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 effect pigments to obtain special colour effects and lustre effects. Preferred pigment preparations comprise one or more effect pigments based on mica and/or SiO
2
flakes.
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 having a content of effect pigments o more than 50% by weight.
As a mandatory component the pigment preparation of the invention comprises a ketonic and/or aldehyde resin in amounts of from 0.5 to 60% by weight, preferably from 5 to 40% by weight and, in particular, from 10 to 30% by weight. All ketonic or aldehyde resins known to the person skilled in the art can be used, especially ketonic and aldehyde resins marketed under the brand name Laropal K80 and Laropal A81 by BASF.
Suitable ketonic resins are obtainable by alkali-catalyzed self-condensation of ketones, for example cyclohexanone or methylcyclohexanone, or by cocondensation of ketones, such as acetone, butanone, acetophenone, cyclohexanone or methylcyclohexanone, with formaldehyde. The resulting ketonic resins are non-hydrolyzable and pale neutral resins which generally soften within the range 80-130° C. Suitable aldehyde resins are polycondensation products obtainable by treating aldehydes, especially acetaldehyde, with strong alkalis.
In accordance with the invention it is preferred to employ those resins which have a low softening or melting point, since in that case the preparations can be produced by an elegant melt process. On the other hand, however, the softening point must not be below room temperature, since then blocking and deficient flow of the dry preparati
Griessmann Carsten
Hechler Wolfgang
Herget Gerhard
Green Anthony J.
Merck Patent GmbH
Millen White Zelano & Branigan P.C.
LandOfFree
Pigment preparation does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pigment preparation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pigment preparation will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3013805