Compositions – Inorganic luminescent compositions – Tungsten containing
Patent
1995-09-25
1997-12-23
Lovering, Richard D.
Compositions
Inorganic luminescent compositions
Tungsten containing
252357, 252 6254, 106504, 5283291, 71 6408, B01J 1300, B01F 1716
Patent
active
057003955
DESCRIPTION:
BRIEF SUMMARY
This application claims benefit of international application PCT/GB94/00379 filed Feb. 25, 1994.
This invention relates to dispersants and to dispersions of solids in organic liquids containing such dispersants.
Dispersants of a polymeric nature in which polyester chains are attached to a polyethyleneimine chain are already known in the art. Thus, our GB-A-2001083 describes dispersants which are reaction products of polyethyleneimine and a polyester having a free carboxylic acid group, the preferred polyesters being derived from hydroxycarboxylic acids having between 8 and 14 carbon atoms between the carboxylic acid and hydroxy groups, for example ricinoleic acid and 12-hydroxystearic acid. In EP-A-0158406 and EP-A-0208041, dispersants are described in which a polyethyleneimine carries poly(carbonylalkyleneoxy) chains in which the alkylene group can contain up to 8 carbon atoms, the preferred chain being a poly(6-hydroxyhexanoate) chain derivable from .epsilon.-caprolactone.
The above mentioned publications describe the use of the dispersants for the production of dispersions of finely divided solids of various types, for example pigments, dyes, magnetic metal oxides, fillers and the like, in organic solvents which may be of low polarity such as hydrocarbons or of higher polarity such as ketones and carboxylic acid esters. Whilst the described dispersants are highly effective for dispersing many pigments in solvents such as ketones and esters, their solubility in these solvents, especially the esters, and particularly at temperatures below the normal ambient temperature, is somewhat limited. The dispersants have a tendency to crystallise out of the ester solvent at temperatures below the normal ambient temperature and this leads to the pigment seeding out of the paint. Dispersions of some pigments may also have undesirable viscosity characteristics using the aforementioned dispersants.
It has now been found that certain dispersants, as hereinafter defined, possess improved solubility characteristics in a wide range of solvents, especially kenone and ester solvents and particularly at temperatures below the normal ambient temperature. Furthermore, dispersions of solids such as organic pigments in several types of solvent have lower viscosities than corresponding prior art dispersions, thus permitting the production of dispersions having higher pigment loadings.
Accordingly, the present invention provides a dispersant comprising a polyethyleneimine residue carrying a plurality of poly(carbonylalkyleneoxy) chains each containing a plurality of repeat units derivable from 6-hydroxyhexanoic acid and at least one other hydroxycarboxylic acid selected from ricinoleic acid, 12-hydroxystearic acid, 12-hydroxydodecanoic acid, 5-hydroxydodecanoic acid, 5-hydroxydecanoic acid and 4-hydroxydecanoic acid, the weight ratio of units derivable from 6-hydroxyhexanoic acid to units derivable from the other hydroxycarboxylic acid or acids being in the range from 90:10 to 10:90, or a salt thereof with an acid.
Preferably, the weight ratio of units derivable from 6-hydroxyhexanoic acid to units derivable from the other hydroxycarboxylic acid or acids is in the range from 20:80 to 80:20, especially from 20:80 to 50:50.
The polyethyleneimine (hereinafter referred to as "PEI") residue present in the dispersants of the invention may be branched or straight-chained and typically has a weight average molecular weight of at least 500, preferably at least 1,000, and especially at least 10,000. The average molecular weight is preferably less than 600,000, more preferably less than 200,000 and especially less than 50,000.
The poly(carbonylalkyleneoxy) chains (hereinafter referred to as "PCAO chains") present in the dispersants of the invention are polyester chains derivable by the polymerisation of the aforementioned hydroxycarboxylic acids (or the corresponding lactones where appropriate) said chains being copolyester chains containing, in block or random arrangement, a plurality of carbonylalkyleneoxy (hereinafter referred to as "CAO")
REFERENCES:
patent: 3778387 (1973-12-01), Stansfield et al.
patent: 4645611 (1987-02-01), Campbell et al.
patent: 4861380 (1989-08-01), Campbell et al.
patent: 5395743 (1995-03-01), Brick et al.
patent: 5418101 (1995-05-01), Holmes et al.
Schofield John David
Thetford Dean
Lovering Richard D.
Zeneca Limited
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