Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Reexamination Certificate
2001-05-14
2002-08-13
Green, Anthony J. (Department: 1755)
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
C106S417000, C106S418000, C106S439000, C106S445000, C106S446000, C106S447000, C106S456000, C106S457000, C106S460000, C106S482000, C106S491000
Reexamination Certificate
active
06432195
ABSTRACT:
The invention relates to a non-dusting, homogeneous pigment preparation which is distinguished by the fact that it comprises one or more effect pigments, e.g., at least 40% by weight, water and/or an organic solvent or solvent mixture, e.g., 0.5-50% by weight and a modified colophony resin, e.g., 0.5-59.5% by weight based on the pigment. Pigment preparations of this type are particularly suitable for the production of dry preparations, such as, for example, granules, chips, briquets, pellets, etc. The invention furthermore relates to the process for the production of the pigment preparation and. dry preparations, and to the use thereof for pigmenting water- and/or solvent-based paints, printing inks, coatings, etc., and plastics.
The use of effect pigments as dry powders in formulations and plastics is frequently afflicted with disadvantages, such as dust evolution and resultant problems at the workplace. A further disadvantage is that agglomeration of the pigment powder is frequently observed on incorporation of effect pigments into plastics, printing inks, industrial coatings, basecoat systems, etc. Homogeneous distribution of the pigment in the respective matrix is frequently difficult or even impossible to achieve.
In order to avoid these disadvantages, non-dusting pigment preparations or pigment-containing dry preparations, such as, for example, granules, are used instead of the pigment powder. The additional treatment of the pigments with a resin improves the applicational properties of the pigments. For treatment of the pigments, modified colophony resins are particularly suitable.
Good properties as printing-inks in offset or letterpress printing are exhibited by dust-free pigment preparations based on organic pigments, such as, for example, azo pigments, which are coated with a mixture of two different resins, for example based on colophony or colophony derivatives, each with a different acid number, as disclosed in EP 0 897 956 A2. A disadvantage here is the use of two coating resins in order to meet the technical requirements of the application.
In order to be able to produce water-thinnable printing inks with high gloss values and good transparency properties based on a non-dusting pigment preparation, EP 0 796 900 A2 describes pigment preparations based on an organic pigment suspended in an aqueous medium and coating thereof with a (colophony) resin having an acid number of ≧200 mg of KOH/g of resin and a nonionic surfactant. The restriction to virtually exclusively water-thinnable printing inks and the use of two chemically very different modifiers comprising strongly “acidic” (colophony) resins and surfactants must be regarded as disadvantages. The latter is also responsible for the compatibility problems of this pigment preparation with a multiplicity of binder systems. A further disadvantage is the tendency towards crystallization of the aqueous solution of these acidic colophony resins.
Besides good compatibility with the other constituents of the coating system, pigment preparations or the dry preparations produced therefrom must result in the coating systems having high stability, i.e. they must not tend towards phase separation, or, where this cannot be completely prevented owing to the low viscosity, it must be easy to return the coating systems to a homogeneous state, i.e. the deposited sediment must be easy to stir up again. This requirement is particularly important in the case of pigment preparations based on platelet-form pigments, since these tend to cake during phase separation owing to their structure and can only be stirred up again with difficulty. Effect pigments based on platelet-form substrates cause handling problems inasmuch as the pigments sediment easily as a consequence of their size and density and can then agglomerate to form a very solid sediment cake. This cake can generally only be stirred up again with difficulty. This applies in particular during the storage of paints, coatings and printing inks, and during processing thereof.
Numerous methods have thus been developed for solving the problem of incorporation and handling of platelet-form pigments in coating compositions. Stirring-up can be made easier by adding to the coating compositions additives which cause either intentional flocculation (house of cards effect), non-Newtonian and/or thixotropic behavior, steric repulsion and/or electrostatic repulsion of the pigments amongst one another. 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 evenness of the coating may be impaired. Furthermore, homogeneous, stable distribution of the redispersants in the pearlescent pigment powder can only be achieved with difficulty, or the redispersant loses effectiveness after incorporation into the system.
The effect pigment preparations having a pigment proportion of ≧30% by weight that have been developed hitherto for use in coating systems frequently only meet the described requirements to an inadequate extent, in particular because they have an increased tendency towards agglomeration and shear thickening.
The present invention therefore provides oxidation-stable pigment preparations based on effect pigments which can simultaneously be used very well in solvent-containing and solvent-free coating systems, have high stability, can be redispersed easily and are simultaneously distinguished by high compatibility with the other components of the coating system. Furthermore, the pigment preparation according to the invention is suitable for the position of dry preparations, for example in the form of pellets, chips, briquets, granules, etc.
Surprisingly, it has been found that these multifarious requirements are achieved by the provision of the pigment preparation according to the invention.
The invention thus relates to a non-dusting, homogeneous pigment preparation which comprises
one or more effect pigments, e.g., ≧40% by wt.
a modified colophony resin,.e.g., 0.5-59.5% by wt., said resin having an acid number of 90-200 mg of KOH/g of resin, a hydroxyl group content of 40-180 mg of KOH/g of resin and a softening range of 50-120° C., and
water or of a solvent or solvent mixture, e.g., 0.5-50% by wt.
based on the pigment preparation.
Depending on the moisture content, the preparation according to the invention is a flowable paste or a moistened, flowable powder. Both are highly suitable for the production of dry preparations, for example granules, chips, pellets or briquets. The dry preparations produced from the pigment preparation according to the invention are likewise a subject-matter of the invention.
The products according to the invention are non-dusting and readily flowable, can be incorporated rapidly into commercially available binder systems and are compatible therein. In particular, the products are compatible with both aqueous, solvent-containing and solvent-free printing ink and coating systems. The inks and coatings produced via the dry preparation, for example granules, are suitable for gravure printing, flexographic printing, screen printing, offset overprint varnish (OPV) and for the various paint systems in the industrial coatings and automobile paints sector. They are also suitable for coloring plastics.
The pigment preparation according to the invention preferably comprises 40-98% by weight of effect pigments, in particular 45-95% by weight. Very particular preference is given to pigment preparations having an effect pigment content of greater than 50% by weight. The % by weight data are always based on the moist, i.e. undried pigment preparation.
The effect pigments used can be pigments based on platelet-form, transparent or semitransparent substrates comprising, for example, phyllosilicates, such as, for example, mica, synthetic mica, SiO
2
platelets, glass platelets, TiO
2
platelets, Al
2
O
3
platelets, talc, sericite, kaolin, glass or other silicate materials, which are coated with rare-earth metal sulfides, such as, for example, Ce
2
S
3
, with colored or c
Griessmann Carsten
Rathschlag Thomas
Sarfert Werner
Schoen Sabine
Green Anthony J.
Merck Patent Gesellschaft mit beschraenkter Haftung
Millen White Zelano & Branigan P.C.
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