Compositions – Preservative agents – Anti-corrosion
Patent
1996-12-13
1998-07-28
Cooney, Jr., John M.
Compositions
Preservative agents
Anti-corrosion
252357, 558108, 558110, 558114, 558153, 558156, 558160, B01F 1730, C07C 6976
Patent
active
057858942
DESCRIPTION:
BRIEF SUMMARY
This application is the national phase of international application PCT/ GB95/01100, filed May 16, 1995 which designated the U.S.
The present invention relates to a compound for dispersing particulate solids in an aqueous medium, its method of preparation and compositions containing said compound and a particulate solid, including paints.
Mill-bases for water-borne paints are conventionally prepared by subjecting an aqueous medium containing a water-insoluble particulate solid such as a pigment to a grinding operation in the presence of a dispersing agent in order to uniformly distribute the finely divided solid throughout the medium. However, when such mill-bases are added to a paint, the dispersing agent can adversely effect the film-forming characteristics of the paint and/or its durability as a paint film. Some dispersing agents also adversely affect the gloss of the resulting paint film. Consequently, improved dispersing agents are required which are capable of dispersing greater amounts of particulate solid in the medium, and exhibiting increased stability of the dispersion and superior properties in the resulting paint film, especially higher gloss finish.
EP 555,950 discloses aqueous mill bases containing a pigment and dispersant which is a polycyclic compound having a poly (C.sub.2-4 -alkyleneoxy) chain containing from 3 to 50 alkyleneoxy groups. Although the dispersant of the present invention also contains a polyalkylene chain it does not contain a terminal polycyclic group such as a naphthalene ring and the present dispersants have been found to provide a paint film with a much superior gloss.
According to the present invention there is provided a dispersant obtainable by reacting a polyethylene glycol (hereinafter "PEG") with a molar excess of a hydroxycarboxylic acid containing from 4 to 17 carbon atoms or lactone thereof (hereinafter "HCA") and/or with a C.sub.3-4 -alkylene oxide (hereinafter "AO") to form a polymeric diol and phosphating the diol by reaction with a phosphating agent to give a phosphate ester. The dispersant may be in the free acid form or it may form a salt with an alkali metal, ammonia, an amine, alkanolamine or quaternary ammonium cation. The phosphate ester group may also be further partially esterified by reaction with an alcohol or may form a salt with an alkanolamine. Thus, in one aspect of the invention the dispersant is derived from a polymeric diol obtainable by reacting a PEG with a molar excess of a HCA.
It is to be understood that the PEG includes block copolymers of ethylene oxide (EO) and propylene oxide (PO) wherein the latter constitutes a middle portion attached at each end to EO units and wherein the amount of PO is less than 50%, preferably less than 30% and more preferably less than 10% by weight relative to the total weight of PEG. It is especially preferred that the PEG consists essentially of EO units.
In another aspect of the invention the dispersant is derived from a polymeric diol obtainable by reacting a PEG with a molar excess of a AO.
In a still further aspect of the invention the dispersant is derived from a polymeric diol obtainable by reacting a PEG with a molar excess of a HCA and a AO wherein the reaction of the PEG with the HCA and the AO is carried out either simultaneously or sequentially.
In all three aspects, the polymeric diol is a block copolymer having terminal hydroxyl groups.
In a preferred aspect of the invention the dispersant is obtainable from a polymeric diol of general formula (1): ##STR1##
Preferably, the repeat unit ##STR2##
is derivable from 6-hydroxyhexanoic acid, ricinoleic acid, 12-hydroxystearic acid, 12-hydroxydodecanoic acid, 5-hydroxydodecanoic acid, 5-hydroxydecanoic acid, 4-hydroxydecanoic acid and .epsilon.-caprolactone including mixtures thereof. It is especially preferred that B is --(CH.sub.2).sub.5 -- and that the repeat unit is derived from .epsilon.-caprolactone.
Preferably, m is at least 3, more preferably at least 4 and especially at least 6. It is preferred that m is less than 40, more preferably less t
REFERENCES:
Perret et al: "Synthese et caracterisation de copolymeres sequences polyoxyethlene/poly-epsilion-carprolactone", Die Makromolchemie, vol. 156, 1972,pp. 143-156-whole document-.
Ehara et al: "Phosphate polymers", Chemical Abstracts, vol. 81, No. 22, Dec. 2, 1974, abstract No. 1367Ow, p. 136756, see abstract & JP,A, 7 451 400 Sep. 14, 1972.
Martini et al:Micellisation and Gelation of Triblock Copolymer of Ethylene Oxide and epsilion-Caprolactone, CL.sub.n E.sub.m CL.sub.n, in Aqueous Solution, J.Chem.Soc.Faraday Trans., 1994, 90 (13) 1961-1966, see p. 1962,col 1.
Schofield John David
Thetford Dean
Cooney Jr. John M.
Zeneca Limited
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