Ether/ester dispersants

Details Ether/ester dispersants Ether/ester dispersants

2003-04-01

2004-04-20

Cheung, William (Department: 1713)

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...

C524S548000, C524S553000, C524S556000

Reexamination Certificate

active

06723782

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a compound for dispersing a particulate solid in a liquid medium, its method of preparation and to compositions and millbases containing said compound and a particulate solid, including paints and inks.
BACKGROUND OF THE INVENTION
WO 97/19948 discloses a dispersant which is a phosphate ester of a block copolymer RO—(C
2
H
4
O)
m
(PES)
n
—OH wherein R is C
1-4
-alkyl, PES is a polyester derived from a cyclic lactone such as valerolactone or &egr;-caprolactone, m is from 5 to 60, n is from 2 to 30 and where the molecular weight of RO(C
2
H
4
O)
m
is greater than the molecular weight of (PES)
n
. The dispersants are said to be particularly effective for dispersing particulate solids such as pigments in an aqueous medium.
It has now been found that dispersants exhibiting superior properties such as solubility in the liquid medium can be obtained by using more than one hydroxycarboxylic acid or lactone to make the polyester (PES)
n
.
SUMMARY OF THE INVENTION
According to the invention, there is provided a dispersant which is a phosphate ester of a polymer which contains at least one ether group and a poly(oxyalkylene-carbonyl) chain derivable from two or more different hydroxycarboxylic acids or lactones thereof including their salts. The dispersant is hereinafter referred to as “Ether dispersant”. Preferably, the poly(oxyalkylenecarbonyl) chain is derivable from two different hydroxy carboxylic acids or lactones thereof. The molecular weight of the polymer can vary between wide limits depending whether the dispersant is to be used for dispersing a particulate solid in a polar liquid medium including water or whether it is for use in a substantially non-polar liquid medium. The molecular weight of the polymer is typically from 200 to 10,000, preferably from 300 to 5,000 and especially from 400 to 2,000.
According to a preferred aspect of the invention, the dispersant is a phosphate ester of a copolymer of formula 1
RO&Brketopenst;(CO—A—O)
n
(CO—B—O)
m
]H  (1)
including salts thereof
wherein
R is a polymerisation terminating group containing at least one ether link;
A and B are each, independently, different alkenylene groups or C
1-17
-alkylene groups optionally substituted by alkyl;
n and m are integers; and
n+m is from 2 to 200.
The copolymer of formula 1 may be a block or random polymer.
In the dispersant of formula 1, [(CO—A—O)
n
(CO—B—O)
m
] represents a polyoxyalkylenecarbonyl chain and the group RO may be attached to either of the oxyalkylenecarbonyl groups containing A and B. It is referred to hereinafter as a polyoxyakylenecarbonyl chain or POAC chain. The copolymer of formula 1 containing the polymerisation terminating group is referred to hereinafter as a TPOAC alcohol.
Where A and/or B is alkenylene it is preferably C
2-17
-alkenylene and especially C
15-17
-alkenylene.
When the dispersant is for use in a non-polar medium, it is preferred that at least one of A and B is C
8-17
-alkylene and when the dispersant is for use in a polar liquid medium, including water, it is preferred that one, or more preferably both, A and B are C
1-6
-alkylene and especially C
4-6
-alkylene optionally substituted by alkyl.
The alkyl substituent in A and B may be linear or branched and is preferably C
1-8
-alkyl, more preferably C
1-6
-alkyl and especially C
1-4
-alkyl.
It is particularly preferred that the molecular weight of the ether moiety RO is greater than that of the POAC chain.
The polymerisation terminating group R containing at least one ether group is preferably a residue of a mono-hydroxy glycol or a mono-hydroxy polyalkyleneglycol. Preferred glycols or polyalkyleneglycols are those derivable from C
2-4
alkyleneoxide, especially ethyleneoxide or propyleneoxide, including mixtures thereof. When the dispersant is for use in a polar liquid, including water, the glycol or polyalkyleneglycol is preferably derivable from ethylene oxide and when the dispersant is for use in a non-polar liquid medium, the glycol or polyalkyleneglycol is preferably derivable from propyleneoxide. When the dispersant is for use in a polar liquid medium, including water, it is particularly preferred that the glycol or polyalkyleneglycol is derivable from ethylene oxide and that both A and B are different C
1-6
-alkylene groups.
Examples of hydroxycarboxylic acids are 12-hydroxystearic, ricinoleic, 12-hydroxydodecanoic, 5-hydroxydodecanoic, 5-hydroxydecanoic, 4-hydroxydecanoic, glycolic, lactic, 6-hydroxyhexanoic and 5-hydroxypentanoic acids.
Examples of lactones are propiolactone, butyrolactone, valerolactone (especially &dgr;-valerolactone) and optionally alkyl-substituted &egr;-caprolactone. The alkyl substituent in &egr;-caprolactone may be linear or branched and is preferably C
1-8
-alkyl, more preferably C
1-6
-alkyl and especially C
1-4
-alkyl. Examples of such groups are methyl and tertiary butyl.
The alkyl-substituted &egr;-caprolactones are obtainable by oxidation of alkyl-substituted cyclohexanone and consequently many are mixtures of alkyl-substituted &egr;-caprolactone. Thus, the oxidation of 2-methyl cyclohexanone often results in a mixture of 7-methyl (95%) and 3-methyl (5%) &egr;-caprolactone. However, the oxidation of 4-alkylcyclohexanone results only in the 5-alkyl &egr;-caprolactone. Other examples of alkyl-substituted &egr;-caprolactone are 6-methyl; 4-methyl; 5-methyl; 5-tertiary butyl; 4,6,6-trimethyl and 4,4,6-trimethyl derivatives. 7-methyl &egr;-caprolactone is the preferred alkyl-substituted &egr;-caprolactone.
The polymerisation terminating group R is preferably derived from a hydroxy compound T-OH which is attached to the glycol or polyalkyleneglycol by an ether linkage wherein T is C
1-35
-hydrocarbyl which is optionally substituted by halogen, tertiary amino, hydroxy, C
1-6
-alkoxy, amine, ester or urethane groups.
When T contains amide, ester or urethane groups it preferably contains two such groups and the group R is preferably a diester, diamide or di-urethane containing at least one ether link. Groups represented by R which contain either amide, ester or urethane groups are conveniently prepared by reacting two fragments of T which contain a hydroxy or amino group with, for example, a dibasic acid or anhydride thereof or a di-isocyanate.
Examples of dibasic acids or anhydrides are terephthalic, phthalic anhydride, adipic acid, maleic acid and maleic anhydride.
Examples of di-isocyanates are toluene di-isocyanate and isophorone di-isocyanate.
The group T may be aromatic, hetrocyclic, alicyclic or aliphatic which may be linear or branched, saturated or unsaturated. It is preferred that T contains not greater than 20 carbon atoms and particularly not greater than 10 carbon atoms. It is especially preferred that T is C
1-6
-alkyl such as methyl.
Other examples of the group T are C
2
H
5
—, CH
3
(CH
2
)
9
—, CH
3
(CH
2
)
11
—, CH
3
(CH
2
)
15
—, CH
3
(CH
2
)
17
—, CH
3
(CH
2
)
29
—, CH
3
(CH
2
)
7
CH═CH(CH
2
)
7
—, CH
3
OCH
2
—, CH
3
(CH
2
)
4
CH═CHCH
2
CH═CH(CH
2
)
7
— the residue of abietyl alcohol, i.e. abietyl alcohol without the OH group, nonylphenol.
As noted hereinbefore, it is particularly preferred that T is C
1-6
-alkyl and also that R is derivable from ethylene oxide since such dispersants have been found particularly effective in dispersing particulate solids in a polar liquid medium, including water.
Examples of R containing at least one ether link are the residue of tripropyleneglycol monomethylether, dipropyleneglycol monomethylether, triethyleneglycol monomethylether, methoxypropyleneglycols and methoxyethyleneglycols having a molecular weight between 250 and 750, ethoxylated C
9-11
-fatty alcohol with a molecular weight of 270 and ethoxylated nonylphenol having a molecular weight of 360.
The dispersant of Formula 1 is obtainable by polymerising two different hydroxycarboxylic acids or lactones thereof in the presence of a monohydric alcohol R—OH to form a TPOAC alcohol having a terminal hydroxy group i.e. a POAC chain having a terminal hydroxy group and a polym

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