Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-05-17
2001-04-17
Truong, Duc (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S495000, C524S497000, C524S080000, C524S081000, C525S419000, C525S420000, C528S310000, C528S328000, C528S363000
Reexamination Certificate
active
06218459
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to aqueous pigment pastes comprising hydrophobically modified polyaspartic acid derivatives as dispersants. The present invention relates in particular to the use of hydrophobically modified polyaspartic acid derivatives as dispersants for preparing aqueous pigment pastes.
2. Prior Art
Pigment pastes for the purposes of the present invention embrace pastes of organic and/or inorganic pigments or fillers in aqueous media. In the preparation of paints and coating materials, wetting agents and dispersants make it easier to incorporate pigments and fillers, which are important formulation constituents as they determine significantly the visual appearance and the physicochemical properties of coatings. To best exploit their effects it is necessary, firstly, for these solids to be distributed uniformly in coating materials and paints and, secondly, for the distribution, once achieved, to be stabilized. Indeed, during the preparation and processing of aqueous pigment pastes, numerous problems may arise:
difficulties in incorporating the pigments
high viscosities of ink pastes, paints and coating materials
sedimentation
vertical migration of pigments (floating)
horizontal migration of pigments (flooding)
low degree of gloss
low hiding power
inadequate depth of color
poor reproducibility of shade
excessive tendency of coating materials to run
There has therefore been no lack of attempts to provide effective dispersing additives for solids, especially pigments. Examples of dispersing additives which are described as being highly suitable for these purposes are water-soluble, polyisocyanate adducts containing hydrophilic polyether chains (see European Publication No. 0 731 148 A), hydrophilic polyurethane-polyureas (see German Publication No. 44 16 336 A), poly(meth)acrylates (see U.S. Pat. No. 3,980,602 and International Patent Publication No. WO 94/21701 A), and specific polyesters (see International Publication No. WO 94/18260 A).
However, the use of such products is also associated with a large number of disadvantages. For instance, high levels of added dispersing additives are often necessary; the levels of paste pigmentation which can be achieved are unsatisfactorily low; the stability of the pastes and thus the constancy of their viscosity is inadequate—flocculation and aggregation cannot always be avoided; in many cases, following a storage of the pastes, there is also a lack of constancy of shade and of compatibility with various binders. The use of known dispersing additives also in many cases has an adverse effect on the water resistance of coatings; moreover, the undesirable foam which forms during preparation and processing is additionally stabilized. A further criterion, whose importance has increased in recent times in particular, is the environmental compatibility of the additives.
It is an object of the present invention to overcome many of the abovementioned disadvantages and in so doing to exert a positive influence in particular on the viscosity and the development of tinctorial strength during the preparation of the pastes and their processing.
SUMMARY OF THE INVENTION
In accordance with the present invention the object is surprisingly achieved by means of one or more hydrophobically modified polyaspartic acid derivatives or their salts and customary auxiliaries and additives.
DETAILED DESCRIPTION OF THE INVENTION
Polyamino acid derivatives, especially polyaspartic acid, have received particular attention in recent times because of their properties. Proposed applications include biodegradable complexing agents, incrustation inhibitors, softeners, and laundry detergent builders. Polyaspartic acid is generally obtained by alkaline hydrolysis of the direct synthesis precursor polysuccinimide (PSI, anhydropolyaspartic acid), the cyclic amide of polyaspartic acid. PSI can be prepared, for example, in accordance with European Publication No. 0 578 449 A, International Publication No.WO 92/14753, European Publication No. 0 659 875 A or German Publication No. 44 20 642 A from aspartic acid or is obtainable, for example, in accordance with German Publication No. 36 26 672 A, European Publication No. 0 612 784 A, German Publication No. 43 00 020 A or U.S. Pat. No. 5,219,952 A from maleic acid derivatives and ammonia.
Reaction of polysuccinimide with amines, which has been described by various groups of workers, leads to polyaspartamides (Kovacs et al., J. Med. Chem. 1967, 10, 904-7; Neuse, Angew. Makromol. Chem. 1991, 192, 35-50). Neri et al. conduct the ring opening of PSI with ethanolamine and obtain hydroxyethylaspartamides (J. Med. Chem. 1973, 16, 893-897, Macromol. Synth. 1982, 8, 25-29). German Publication No. 37 00 128 A and European Publication No. 0 458 079 A describe the subsequent esterification of such hydroxyethyl derivatives with carboxylic acid derivatives and the use of the products in ultrasound contrast agents and in active substance depot formulations.
German Publication No. 195 24 097 Al describes products of esterification of polyaspartic acid with fatty alcohols. While, however, homogeneous reaction products prepared under the customary esterification conditions are difficult to prepare, copolymeric, hydrophobically modified polyaspartic esters based on maleic monoesters and ammonia or on polysuccinimide and alcohols are easy to obtain, as is evident from German Publication No. 195 45 678 or European Application No. 96 118 806.7.
In compounds of this kind, which can be deployed to advantage in wetting agents and dispersants, some of the side chains are in the form of free carboxylic acid or carboxylate groups and some are esterified with one or more alcohols of 1 to 18 carbon atoms, preferably of 8 to 12 carbon atoms, or derivatives thereof.
For example, copolymers derived from polyaspartic acid can be employed in which at least 75 mol % of the units consist of structural units of the general formulae (I) and (II) where A is a trifunctional hydrocarbon radical of 2 carbon atoms with the structure (A1) or (A2),
in which R
1
has the definition of R
2
, R
3
or R
4
where
R
2
is one or more radicals from the group consisting of alkali metals, alkaline earth metals, hydrogen and ammonium, [NR
5
R
6
R
7
R
8
]
+
, where
R
5
to R
8
independently of one another are hydrogen, alkyl or alkenyl of 1 to 22 carbon atoms or hydroxyalkyl of 1 to 22 carbon atoms and 1 to 6 hydroxyl groups,
R
3
is identical or different, straight-chain or branched, saturated or unsaturated alkyl or alkenyl radicals R
9
of 6 to 30 carbon atoms or is radicals of the structure —X—R
9
, where X is an oligooxyalkylene or polyoxyalkylene chain of 1 to 100 oxyalkylene units, and
R
4
is identical or different, straight-chain or branched, saturated or unsaturated alkyl or alkenyl radicals of 1 to 5 carbon atoms
and at least one radical R
1
must adopt the definition of R
2
and at least one radical R
1
must adopt that of R
3
or R
4
and
the units of the general formula (II) are proteinogenic or nonproteinogenic amino acids and are present in a proportion of not more than 20% by weight based on the copolymeric polyaspartic acid derivatives.
With particular preference R
1
has the definition of R
3
.
The remaining units, which do not have the structure (I) or (II) (not more than 25 mol % of all units), may inter alia be iminodisuccinate units of the general formula (III)
and also various end groups: at the N end, for example, aspartic acid, maleic acid, fumaric acid and malic acid units and their esters or amides, maleimide units or diketopiperazines derived from aspartic acid and/or the amino acid units (II), and also esters or amides of the amino acid units (II), and at the C end, for example, aspartic or malic acid units, their monoesters or diesters, amides or cyclic imides.
All of the information given regarding the composition of the polymeric products relates as usual to the average composition of the polymer chains.
Examples of suitable amino acid units (II) from the group of protein
Gruning Burghard
Silber Stefan
Simpelkamp Jorg
Weitemeyer Christian
Scully Scott Murphy & Presser
Th. Goldschmidt Ag
Truong Duc
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