Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Reexamination Certificate
2000-12-13
2003-04-15
Green, Anthony J. (Department: 1755)
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
C106S415000, C106S416000, C106S418000, C106S439000, C106S445000, C106S446000, C106S447000, C106S457000, C106S482000, C106S487000, C106S490000, C106S491000, C106S499000, C106S501100, C106S504000, C106S031600, C106S031670, C106S031690, C106S031900, C428S403000, C428S404000, C428S407000, C524S437000, C524S447000, C524S449000
Reexamination Certificate
active
06547870
ABSTRACT:
The invention relates to a non-dusting homogeneous pigment preparation and to its use as a precursor for printing inks.
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 described for example in DE-C-2603211,
pigmented free-flowing powders with a low moisture content, as known, for example, from DE-A-4139993,
pigmented powders having a higher moisture content, which owing to their flowable consistency are also frequently referred to as pastes, or
dry preparations as precursors for printing inks, as are known for example in 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 so that the formulation is customized to suit the other components of the respective coating system as closely as possible 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 granules based on platelet-shaped pigments, since owing to their structure such pigments have a tendency to cake together 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 then may cake together to form a very firm sediment cake. This cake is generally difficult to reagitate. This is particularly so in connection with the storage of varnishes, paints and printing inks and their processing.
Therefore, 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 effect pigment formulations that have been developed to date for use in coating systems, with a pigment content of >30% by weight, frequently fail to go far enough towards meeting the requirements described, especially since they have a tendency towards agglomeration and shear thickening.
The object of the present invention was therefore to provide a pigment preparation, especially in the form of pastes and dry preparations, which can be used to very good effect in aqueous coating systems, possesses high stability, is readily redispersed, and at the same time features 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 a polyalkylene glycol
and/or one or more polyalkylene glycol
derivatives,
0-10%
by weight of a redispersing auxiliary,
0-40%
by weight of water or an organic solvent
or solvent mixture,
0-40%
by weight of at least one further
hydroxyl-rich resin.
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 highly suited to the production of dry preparations, examples being pellets, granules and briquettes. The dry preparations produced lrom the pigment formulation of the invention are likewise provided by the invention.
The effect pigments used are preferably commercially customary metal-effect pigments, such as aluminium flakes, e.g. Stapa-Alupaste® or Standart from Eckart, Paliochrom® from BASF, platelet-shaped iron oxide, BiOCl, holographic pigments, and also pigments based on platelet-shaped, transparent or semi-transparent substrates of, for example, phyllosilicates, such as mica, synthetic mica, SiO
2
flakes, TiO
2
flakes, Al
2
O
3
flakes, glass flakes, graphite flakes, talc, sericite, kaolin or other silicatic materials which are coated with coloured or colourless metal oxides, such as TiO
2
, titanium suboxides, titanium oxinitrides, Fe
2
O
3
, Fe
3
O
4
, SnO
2
, Cr
2
O
3
, ZnO, CuO, TiO 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 Iriodine® from Merck KGBA, Darmstadt, FRG. Particularly preferred pigment granules 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 granules comprise one or more effect pigments based on mica and/or SiO
2
flakes.
It is also possible to mix in conventional (organic or inorganic) colour pigments and also carbon black and/or TiO
2
.
The pigment formulation of the invention comprises preferably 50-95 t by weight of effect pigments, especially 60-80% by weight. Very particular preference is given to pigment granules having an effect pigment content of more than 50% by weight.
As a mandatory component the pigment preparation of the invention comprises a polyalkylene glycol and/or an appropriate derivative 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 polyalkylene glycols or derivatives thereof that are known to the person skilled in the art can be used. Polyethylene glycol, polypropylene glycol and their esters and ethers are particularly suitable, as are described, for example, in “Encyclopaedia of Polymer Science and Engineering”, a Wiley-Interscience Publication, John Wiley & Sons.
Furthermore, it is often advisable to mix in hydroxyl-rich resins, examples being cellulose products such as carboxycellulose and its ethers and esters, polyvinyl alcohol, polysaccharides and polyvinyl acetate, in amounts of from 0-50% by weight. All hydroxyl-rich resins known to the person skilled in the art are suitable, especially those specified in Karsten, Lackrohstofftabellen, 8th edition 1987.
As a further compon
Griessmann Carsten
Herget Gerhard
Green Anthony J.
Merck Patent Gesellschaft mit Beschränkter Haftung
Millen White Zelano & Branigan P.C.
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