Compound, preparation and use

Details Compound, preparation and use Compound, preparation and use

1998-06-01

2000-10-17

Jagannathan, Vasu

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...

524845, 525408, 523160, 523161, C08L 6704, C08L 7102, C08L 4302, C09D 1102, C09D 1116

Patent

active

061333662

DESCRIPTION:

BRIEF SUMMARY
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 and inks.
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 both a resin and 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 it 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.
Canadian Patent Application No 2,022,957 discloses dispersants which are phosphate esters of block copolymers which contain both poly(alkyleneoxy) and polyester chain segments and specifically a phosphate ester of a block copolymer which is polyethyieneglycolmonomethyl ether of MW 750 polymerised with valerolactone which also gives rise to a polyester of MW 750. It has now been found that phosphate esters of block copolymers of this type exhibit superior properties as dispersants for aqueous millbases if the MW of the polyethyleneglycol chain segment is greater than the MW of the polyester chain segment.
According to the present invention there is provided a dispersant which is a phosphate ester of a block copolymer of formula 1 the molecular weight of (PES).sub.n. methyl.
The cyclic lactone is preferably valerolactone and especially .epsilon.-caprolactone. When PES represents a polyester derived from valerolactone, the repeat unit is of formula --O--(CH.sub.2).sub.4 CO-- or --O--CH(CH.sub.3)--(CH.sub.2).sub.2 CO-- and when PES represents a polyester derived from .epsilon.-caprolactone, the repeat unit is of formula --O--(CH.sub.2).sub.5 CO--.
Preferably m is not greater than 40 and especially not greater than 25.
It is also preferred that n is not greater than 20 and especially not greater than 10.
Preferably the ratio of m:n is not less than 3:1, more preferably not less than 4:1 and especially not less than 6:1.
The MW of the block copolymer of formula 1 is preferably less than 5,000, more preferably less than 4,000, even more preferably less than 3,500 and especially less than 3,000.
The phosphate ester is obtainable by reacting the monoalkyl ether of formula 1 with a phosphating agent wherein the ratio of monoalkyl ether to each phosphorus atom of the phosphating agent is from 3:1 to 1:1 and especially from 2:1 to 1:1.
It is especially preferred that the ratio of monoalkyl ether to each phosphorus atom of the phosphating agent is less than 2, for example, about 1.5:1 when the dispersant is a mixture of mono- and di-phosphate esters.
The phosphate ester may be in the form of a free acid or it may form a salt with an alkali metal, ammonia, an amine, alkanolamine or a quaternary ammonium cation.
The phosphate ester may also be further reacted with an alkanol or alkanolamine. Preferred alkanols are C.sub.1-6 - and especially C.sub.1-4 -alkanols. When the phosphate ester is further reacted with the alkanol additional ester groups are formed and the ratio of the monoalkyl ether of formula 1 to the phosphorus atom of the phosphating agent is less than 2 and especially less than 1.5.
When the phosphate ester is reacted with an alkanolamine, the alkanolamine may form ester and/or amido groups and/or amine salts. It is believed that the reaction product is mainly an amine salt.
Preferred phosphating agents are POCl.sub.3, polyphosphoric acid and especially P.sub.2 O.sub.5.
Preferably, the alkali metal is lithium, potassium and especially sodium.
Examples

REFERENCES:
patent: 3312753 (1967-04-01), Bailey, Jr. et al.
patent: 4500686 (1985-02-01), Kobayashi et al.
patent: 4704165 (1987-11-01), Nakamura et al.
patent: 5151218 (1992-09-01), Haubennestel et al.
patent: 5320673 (1994-06-01), Carpenter
patent: 5929177 (1999-07-01), Kataoka et al.
Morrison, Robert Thornton and Boyd, Robert Neilson; Organic Chemistry 5thEd., Allyn and Bacon, Inc, Boston (p. 874), 1987.

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