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
2000-10-30
2003-01-21
Niland, Patrick D. (Department: 1714)
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...
C524S590000, C524S591000, C524S839000, C524S840000, C528S044000, C528S060000, C528S065000, C528S066000, C528S073000, C528S080000, C528S081000, C528S084000, C528S085000
Reexamination Certificate
active
06509409
ABSTRACT:
The present invention relates to dispersing agents derived from a polyisocyanate and at least one poly(oxyalkylenecarbonyl) chain derived from two or more different hydroxycarboxyylic acids or lactones thereof.
U.S. Pat. No. 4,647,647 discloses dispersants made by reacting a polyisocyanate having an average functionality of from 2.5 to 6 with a monohydroxy compound containing O and COOH groups. Examples of monohydroxy compounds include the reaction products of heptadecafluorodecanol, 2-ethylhexanol and valerolactone; and the reaction product of caprolactone with the following hydroxy compounds as polymerisation terminating groups: phenylethylalcohol, n-octanol, isononanol, nonylphenolethyoxylate (MW 445), trimethylolpropane and 1,4-butanediol. These dispersants are said to resist reagglomeration of solids after the dispersion process, to give high gloss in lacquers and coatings, high colour in pigmented plastics and good mechanical strength in reinforced plastics.
U.S. Pat. No. 4,795,790 discloses similar polyisocyanate derived dispersants which contain either acidic, basic or alkoxysilane groups.
U.S. Pat. No. 5,399,294 and U.S. Pat. No. 5,425,900 also disclose similar polyisocyanate derived dispersants which additionally contain a compound having at least one basic ring nitrogen atom and an isocyanate-reactive group.
WO 97/26984 also discloses polyisocyanate derived dispersants containing a 2 0 cyclic group having a ring nitrogen which is derived from an acrylate or epoxide.
In so far as these dispersants contain a poly(oxyalkylenecarbonyl) chain such chains are derived from a single hydroxycarboxylic acid or lactone thereof.
It has now been found that improved dispersants can be obtained by incorporating a poly(oxyalkylenecarbonyl) chain obtainable from two or more different hydroxy carboxylic acids or lactones thereof. In many instances, the dispersants also exhibit improved solubility compared with similar dispersants containing a poly(oxyalkylenecarbonyl) chain derived from a single hydroxy carboxylic acid or lactone thereof.
According to the invention there is provided a dispersant comprising the addition reaction product of a polyisocyanate having an average functionality of from 2 to 10 and one or more poly(oxyalkylenecarbonyl) chains derivable from two or more different hydroxy carboxylic acids or lactones thereof, including their salts. (Hereinafter “The Dispersant”).
Polyisocyanates having an average functionality of from 2 to 6 are preferred.
It is particularly preferred that the polyoxyalkylene chain is derivable from two different hydroxycarboxylic acids or lactones thereof.
Preferably, the poly(oxyalkylenecarbonyl) chain (hereinafter POAC chain) contains C
1-17
-alkylene groups. The nature of the chain length can be varied between wide limits depending on whether the dispersant is to be used to disperse a particulate solid in a polar or non-polar medium. Thus, when the dispersant is to be used to disperse a particulate solid in a non-polar medium, preferably one or more of the hydroxy carboxylic acids contains a C
7-17
-alkylene group and when the dispersant is to be used to disperse a particulate solid in a polar medium it is preferred that one or more and especially all of the hydroxy carboxylic acids or lactones thereof contains a C
1-6
-alkylene group.
The hydroxy carboxylic acids may be linear or branched, saturated or unsaturated. Preferably, the hydroxy carboxylic acid is saturated.
Examples of hydroxy carboxylic acids containing a C
7-17
-alkylene group are ricinoleic, 12-hydroxystearic, 12-hydroxydodecanoic, 5-hydroxydodecanoic, 5-hydroxydecanoic and 4-hydroxydecanoic acids.
Examples of hydroxy carboxylic acids containing a C
1-6
-alkylene group are glycolic, 5-hydroxyvaleric and 6-hydroxycaproic acid.
When the POAC chain contains one or more C
1-6
-alkylene groups it is preferably obtained by polymerising one or more lactones. Examples of lactones are propiolactone, butyrolactone, valerolactone and caprolactone. It is particularly preferred that the lactone is &dgr;-valerolactone or &egr;-caprolactone which is optionally substituted by C
1-8
-alkyl more preferably C
1-6
-alkyl and especially C
1-4
-alkyl. Examples of such alkyl groups are methyl and tertiary butyl. Particularly useful effects have been obtained where the POAC chain is obtained by copolymerising &dgr;-valerolactone and &egr;-caprolactone.
The alkyl-substituted &egr;-caprolactones are obtainable by oxidation of alkyl-substituted cyclohexanones 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-alkyl cyclohexanone 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 preferred.
Copolymerisation of the hydroxy carboxylic acid or lactone thereof results in a POAC chain having a terminal hydroxy group and a terminal carboxylic acid group. (Hereinafter POAC compound). The POAC compound may be reacted at either the hydroxy and/or carboxylic acid group with a compound containing a functional group which undergoes an additional reaction with isocyanates such as hydroxy, thiol or amino groups. It is preferred, however, that the POAC compound undergoes an addition reaction with the polyisocyanate via the hydroxy group of the POAC compound. The POAC chain may be prepared by first reacting a hydroxy carboxylic acid with the isocyanate group(s) of the polyisocyanate followed by copolymerisation with additional hydroxy carboxylic acid or lactone thereof to build the POAC chain. However, it is preferable to first prepare the POAC compound and to react this with the isocyanate group(s) of the polyisocyanate. In this case it is preferable to carry out the copolymerisation of the hydroxy carboxylic acid or lactone thereof in the presence of a polymerisation chain terminator. The chain terminator may contain a thiol, primary or secondary amino group, but preferably contains a hydroxy group. The POAC compound derived from two different hydroxycarboxylic acids or lactones thereof and which contains a chain terminator attached to the POAC chain via the carbonyl group is a compound of formula 1.
T[—(CO—A—O)
n
(CO—B—O)
m
]H (1)
wherein
T is a chain terminating group;
A and B are different C
1-17
-alkylene;
n and m are integers; and
n+m is from 2 to 200.
The POAC compound of formula 1 is hereinafter referred to as a TPOAC alcohol.
As noted hereinbefore, the chain terminator preferably contains a hydroxy group when the different hydroxycarboxylic acids or lactones thereof are copolymerised in the presence of T—OH.
T is optionally substituted C
1-35
-hydrocarbyl and may be aromatic, alicyclic, heterocyclic or aliphatic which may be linear or branched, saturated or unsaturated. Preferably, T contains not greater than 20 carbon atoms and more preferably not greater than 10 carbon atoms.
Optional substituents include halogen, C
1-6
-alkoxy, ester (i.e. —OCO—), amide, urethane and ether groups. When T-OH contains one or more ether groups it is preferably derivable from propylene and/or ethylene oxide. Thus, T—OH may be a monohydric alcohol or phenol which is (co) polymerised with propylene and/or ethylene oxide. Examples of monohydric alcohols are C
1-20
-aliphatic alcohols which may be linear or branched, saturated or unsaturated such as phenoxyethanol, octanol, C
11-16
-fatty alcohols, nonanol, ethanol, butanol and methanol. Examples of phenols (co) polymerised with propylene and/or ethylene oxide are nonylphenol and &bgr;-naphthol.
When T contains ester, amide or urethane groups, such groups may be made by linking chain fragments of T which contain amino or hydroxy groups using dibasic acids or anhydrides or di-isocyanates. Examples of compounds capable of such cross-linking chain fragments of T are teraphthalic acid, adipic acid,
Avecia Limited
Niland Patrick D.
Pillsbury & Winthrop LLP
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