Emulsions

Details Emulsions Emulsions

2001-12-10

2003-09-02

Yoon, Tae H. (Department: 1714)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

C523S504000, C524S221000, C524S249000, C524S250000, C524S845000

Reexamination Certificate

active

06613817

ABSTRACT:

This invention relates to emulsions and in particular to aqueous emulsions and/or dispersions of resins and/or polymers, especially alkyd resins, in which the emulsifier includes unsaturated fatty acid amides and to the production of such emulsions and/or dispersions.
Curable alkyd resins, often referred to as “air drying” alkyds, are used widely in industry in surface coatings such as paints, in particular decorative paints. They are well known materials and generally, they are film forming polyesters including residues of polybasic, usually di-basic, acid(s) and polyhydroxy, usually tri- or higher hydroxy alcohols and further including monobasic unsaturated (often multiple unsaturated) fatty acid residues. Such alkyd resins may include other residues and/or additives to provide specific functionality for the intended end use e g. sources of additional carboxyl groups may be included to improve resin emulsifyability. Curable alkyds are widely included in paints which may be solvent based, water based or use mixed solvent/water vehicles, in which the alkyd is in the dispersed phase. The alkyds are usually formed into an emulsion before incorporation into the paint and in such emulsions the alkyd is typically dispersed in the water phase as uniformly and generally as finely as is possible and commonly surfactants, particularly emulsifiers, are used to aid this.
Emulsifiers can contribute to fine and uniform alkyd resin droplets in emulsions. Typical emulsifiers are relatively low molecular weight surfactant materials which in emulsions are concentrated at least relatively at or near the resin/water interface. However, during drying of resin films made from emulsions, the emulsifiers tend to migrate to and accumulate either near the air/film or near the substrate/film interfaces and can have adverse effects on film water sensitivity, gloss retention, reduced adhesion on substrate, film haze, and on film hardness. Some of these effects can be mitigated by using reactive emulsifiers. For example, WO92/09667A describes the use of fatty acid alkoxylates of the general formula: R—CO—NH—(C
m
H
2m
)—O—(AO)
n
—H, where R is C
7
to C
23
polyunsaturated alkyl, m is 2-4, AO is an alkylene oxide residue, and n is 2-30, which are described as participating in the curing of the binder, thus reducing some of the adverse effects of surfactants. However, alkoxylate emulsifiers have a disadvantage in that although they can be very effective emulsifiers for alkyds, they are known to have adverse effects on the film forming/drying process.
The present invention is based on our finding that certain types of polyhydroxyhydrocarbyl substituted amides of polyunsaturated fatty acids are effective emulsifiers for alkyd resins, particularly unsaturated curable alkyd resins, and can give well cured films without deactivating typical alkyd drying catalysts, to give films of high hardness and having good water resistance.
The invention accordingly provides an aqueous emulsion of a resin which includes as an emulsifier at least one compound of the formula (I):
R
1
—CO—NR
2
R
3
  (I)
R
1
is a polyunsaturated hydrocarbyl group;
R
2
is a polyhydroxy hydrocarbyl radical; and
R
3
is hydrogen, a hydrocarbyl, particularly alkyl, group, a hydroxy or hydrocarbyloxy substituted hydrocarbyl, particularly hydroxy or alkoxy substituted alkyl, or is a group as defined for R
2
.
The invention also includes a paint which includes:
(1) an aqueous or mixed aqueous organic continuous phase;
(2) an alkyd resin emulsion discontinuous phase;
(3) at least one compound of the formula (I) (as defined above) as an emulsifier; and
(4) at least one pigment.
The group R
1
is a polyunsaturated hydrocarbyl group i.e. it includes at least 2, particularly 2 or 3, ethylenic double bonds, and desirably is a C
7
to C
23
, particularly C
9
to C
21
, hydrocarbyl especially an open chain e.g. alka di-, tri or higher-enyl, group. Desirably the group R
1
contains 2 double bonds and is especially an alkadienyl group. In naturally occurring unsaturated fatty acids the double bonds are usually (internal) cis-double bonds e.g. in linoleic acid the double bonds are both cis within a group —CH═CH—CH
2
—CH═CH— in the chain. The double bonds can be conjugated, but as the most readily available doubly unsaturated fatty acid is linoleic acid they will usually not be conjugated (although the double bonds is such materials can migrate to become conjugategd and or somerise from cis to trans, especially in the presence of a catalyst such as strong base).
The group R
2
is a polyhydroxy hydrocarbyl, particularly polyhydroxy alkyl, group, and desirably has a linear C
4
to C
7
chain and at least three hydroxyl groups directly bonded to chain carbon atoms. The group may include substituents, in particular, alkoxy groups e.g. by etherification of further hydroxyl groups or further polyhydroxy hydrocarbyl, e.g. polyhydroxy alkyl, group(s), but the group desirably includes at least three free hydroxyl groups including such hydroxyl groups on substituents of the basic chain. Particularly R
2
is an open chain tetratol, pentitol, hexitol or heptitol group or an anhydro e.g. cycloether anhydro, derivative of such a group. Especially desirably, R
2
is the residue of, or a residue derived from, a sugar, particularly a monosaccharide such as glucose, fructose or sorbitol, a disaccharide such as maltose or palitose or a higher oligosaccharide. It is particularly convenient that R
2
is the residue of a reducing sugar, because the amines can be made by straightforward reductive alkylation reactions on an amine H
2
NR
2
.
In the compounds of this invention the group R
2
is present as or as part of the hydrophile. Thus it will usually be desirable that the hydrophilicity of this group is not unduly reduced. The open chain form of such groups is typically the most hydrophilic form and will thus usually be the form desired. Groups including internal cyclic ether functionality can however be used, if desired, and may be obtained inadvertently if the synthetic route exposes the group to relatively high temperatures or other conditions which promote such cyclization.
Where R
2
is the residue of, or a residue derived from, a monosaccharide, the saccharide derived group or residue will usually be present as an open chain material. Where R
2
is the residue of, or a residue derived from, an oligosaccharide it can be considered as an open chain monosaccharide derived group or residue with a saccharide or oligosaccharide substituent which may be cylclic ar a chain of cyclic residues. Particularly useful R
2
groups are derived from glycoses and are of the formula: —CH
2
—(CHOH)
4
—CH
2
OH, e.g. corresponding to residues from glucose, mannose or galactose. In this case the group —NR
2
R
3
is of the formula: —NR
3
—CH
2
—(CHOH)
4
—CH
2
OH and the group is conveniently called a glycamine group and the corresponding amides can be called glycamides. Most commonly the group R
2
will be derived from glucose and the corresponding amine and amides may be called glucamines and glucamides or as sorbityl amines or amides (though strictly they are 1-deoxyglucitylamines and 1-deoxyglucitylamides) respectively.
When R
3
is hydrocarbyl, it is desirably a C
1
to C
10
hydrocarbyl, particularly an alkyl group. When R
3
is hydroxy or hydrocarbyloxy substituted hydrocarbyl it is desirably a C
1
to C
6
hydrocarbyl, particularly an alkyl group substituted with hydroxy as in 2-hydroxyethyl, or a C
1
to C
6
alkoxy group as in 2methoxyethyl or 2-ethoxyethyl. When R
3
is a group R
2
it will usually be the same as the other group R
2
, thus making the overall amino function a bis(polyhydroxy hydrocarbyl)amino group, for example a bis-(1-deoxyglucityl)amino group which may also be called a bis-(sorbityl)amino group.
The compounds of the formula (I) are typically made by reacting a polyunsaturated fatty acid of the formula (II): R
1
COOH (II) where R
1
is as defined above, or a reactive derivative of such an acid e.g. a C
1
to C
4
ester such as a methyl or ethyl ester,

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