Drier catalyst for coating compositions

A drier catalyst for use in coating compositions which contain polyunsaturated oils comprises a coordination complex of tri n-octylphosphine oxide and the manganese salt of a hydrocarbon-soluble carboxylic acid, such as octoic acid. The catalyst is unaffected by the presence of zinc compounds or iron in the coating composition.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to drier catalysts for use in coating 
compositions and, more particularly, this invention relates to the use of 
an organic coordination complex of a manganese salt as a drier catalyst in 
oleoresinous coating compositions. 
2. Description of the Prior Art 
The use of various metal salts, such as salts of cobalt, zirconium, calcium 
and manganese, for example, as so-called "drier catalysts" in coating 
compositions is well known. Such drier catalysts promote the oxidative 
polymerization of the polyunsaturated oils in the composition after 
application in order to effect drying. 
It is known that some coordination complexes of drier metals are more 
effective as oxidative catalysts than are the uncomplexed metal ions. For 
example, 1,10-phenanthroline forms coordination complexes with many 
metals, especially with manganese and cobalt, whereby the activity and 
stability or the metal is increased. See, for example, Canty et al, 
"1,10-Phenanthroline Promotes Drying of Paints" in Paint Industry (April 
1960) and Canty et al, "1,10-Phenanthroline-Drier Catalyst Activity in 
Organic Coatings", Ind. & Eng. Chem., Volume 52, pages 67-70 (January 
1960). 
While useful, prior drier metal complexes exhibit several disadvantages. 
For example, 1,10 phenanthroline is quite costly, and, perhaps more 
importantly, is not effective in the presence of zinc oxide or zinc salts. 
Zinc oxide is frequently used in paints to prevent the growth of mildew, 
to improve color retention and, usually in conjunction with zinc chromate, 
zinc phosphate or zinc dust, to improve corrosion resistance. 
Furthermore, 1,10-phenanthroline is a specific indicator for iron ions in 
concentrations as low as several ppm. At the acidic pH levels of resins 
and oils used in paints, 1,10-phenanthroline turns pink in the presence of 
a few ppm of iron and, since iron is frequently found in trace quantities 
in coating compositions, the use of 1,10-phenanthroline in the composition 
tends to turn the composition pink. This is a particular problem in water 
based paints, because any exposure thereof to uncoated steel will result 
in some pickup of iron ions from the environment. 
SUMMARY OF THE INVENTION 
It is an object of the invention to overcome one or more of the problems 
described above. 
According to the present invention, a coordination complex of tri 
n-octylphosphine oxide (sometimes referred to herein as "TOPO") and a 
manganese salt of a hydrocarbon soluble carboxylic acid is used as an 
oxidative polymerization catalyst in oleoresinous coating compositions. 
The carboxylic acid is preferably octoic acid, naphthenic acid or tallate 
acid. 
The invention also comprehends a solution of the coordination complex and 
an aromatic hydrocarbon solvent which is suitable for introduction to 
coating compositions. 
The inventive chelate is effective in the presence of zinc oxide and zinc 
salts, and is not affected by the presence of iron. 
Other objects and advantages of the invention will be apparent from the 
following detailed description, taken in conjunction with the appended 
claims. 
DETAILED DESCRIPTION OF THE INVENTION 
The drier catalyst of the invention is useful in any paint or other coating 
composition which incorporates a polyunsaturated oil, such as vegetable 
oil, as a component of the system. Such compositions include, without 
limitation, coatings based on solutions of oleoresinous binders in organic 
solvents, coatings based on emulsions or solutions of oleoresinous binders 
in water, and coatings based on oleoresinous modified latex in water. 
Typical coatings include flat house paints, gloss house paints, 
water-borne alkyd enamels, acrylic latex house paint and alkyd enamels. 
The catalyst may also be incorporated into a preprepared alkyd modifier 
for use in latex paints. 
The function of the catalyst is to promote the oxidative polymerization of 
the unsaturated oils which are present in the coating compositions, 
thereby forming a solid film (as opposed to a liquid film) in a manner 
within the time span which is typically referred to as "drying" by those 
skilled in the art of formulating coating compositions. 
As set forth above, the catalyst comprises a coordination complex of tri 
n-octylphosphine oxide (an organic chelating agent) and the manganese salt 
of a hydrocarbon soluble carboxylic acid. 
The chelating agent, tri n-octylphosphine oxide ("TOPO"), is an 
organophosphorus compound which is soluble in commonly used aliphatic and 
aromatic solvents. TOPO is a waxy solid at room temperature. In order to 
obtain a concentration of TOPO suitable for normal use in coating 
compositions, the TOPO should be dissolved in a solvent which comprises at 
least about 30 wt. % of an aromatic hydrocarbon. If desired, higher 
levels, up to 100%, of the aromatic solvent may be used. 
For example, 100% of a so-called "heavy aromatic solvent" may be used, as 
may 100% xylol, or a mixture of xylol and another solvent, such as mineral 
spirits. 
The choice of carboxylic acid used in the manganese salt is not critical, 
although the acid should be hydrocarbon soluble. Preferred acids are 
octoic acid, naphthenic acid and tallate acid. 
Methods of preparation of the manganese salts of such acids are well known 
to those skilled in the art, and such salts are readily commercially 
available. 
The catalyic coordination complex of the invention may be readily prepared 
by simple mixing of the TOPO and the manganese salt in the presence of a 
suitable aromatic solvent. It is preferred to prepare the chelate in 
advance of addition to the coating composition to ensure that the chelate 
is properly formed. This is especially true when there are competing metal 
ions present in the paint formula. If there are no such competing metal 
ions present in the composition, the manganese salt and the TOPO may be 
added separately to the coating composition. 
Preferably, the concentration in the coating composition of manganese metal 
present in the catalyst should be at least 0.02 wt. %, based on the total 
weight of resin and oil solids present in the composition. If desired, a 
higher catalyst concentration may be used, but higher concentrations are 
less cost effective. Also, lower concentrations may be used, but a 
decrease in manganese concentration to less than about 0.02 wt. % results 
in poorer drying characteristics of the composition. 
In order to formulate a coating composition with the desired manganese 
metal concentration, it is convenient to prepare a solution of the chelate 
having a standard manganese concentration, such as about 2.0 wt. %, for 
example. 
In this regard, it is noted that manganese salts of the preferred octoic 
acid, naphthenic acid, or tallate acid are conventionally available in 
metal concentrations of 6, 12 or 18 wt. %. 
In order to obtain a chelate solution having a 2.0 wt. % concentration of 
manganese, it is necessary to use a 16.65 wt. % solution of a manganese 
salt which is 12% metal. Accordingly, a solution comprising 33.3 wt. % of 
the 6% metal salt will provide a 2.0 wt. % solution, and an 11.1 wt. % 
solution of 18% manganese salt will provide such a solution.

EXAMPLES 
The following specific Examples illustrate various embodiments of the 
invention and are not to be considered as limiting in any way. In the 
Examples, all parts are by weight. 
EXAMPLE 1 
A preferred embodiment of a solution of the catalyst of the invention is 
prepared by mixing 47.50 parts of TOPO, 35.85 parts of heavy aromatic 
solvent, and 16.65 parts of 12% manganese octoate for a total of 100 
parts. This solution has a manganese metal concentration of 2.0 wt. %. 
EXAMPLE 2 
A second preferred embodiment of a solution of the catalyst of the 
invention is prepared by mixing 47.50 parts of TOPO, 16.65 parts of 12% 
manganese octoate, 14.75 parts of xylol, and 21.10 parts of mineral 
spirits, for a total of 100 parts. This solution also has a manganese 
metal concentration of 2.0 wt. %. 
EXAMPLES 3-8 
The following specific Examples illustrate various paints and enamels 
incorporating the catalyst solution of either of Examples 1 or 2. 
EXAMPLE 3 
A flat house paint is prepared by mixing the following ingredients in the 
indicated proportions: 
______________________________________ 
Long Oil Alkyd (70% NVM)* 
240.0 
Castor Wax 8.0 
Organo Montmorillonite Clay 
5.0 
Mineral Spirits 237.1 
Heat Bodied Linseed Oil (80% NVM) 
55.0 
Heat Bodied Linseed/Tung Oil (54% NVM) 
43.7 
Raw Linseed Oil 27.1 
Fungicide 10.0 
Methyl Ethyl Ketoxime 1.9 
Titanium Dioxide 225.0 
Calcium Carbonate 40.0 
Magnesium Silicate 50.0 
Mica 50.0 
Diatomaceous Silica 100.0 
Catalyst Solution 2.6 
______________________________________ 
*Nonvolatile matter 
EXAMPLE 4 
A gloss house paint is prepared by mixing the following ingredients in the 
indicated proportions: 
______________________________________ 
Long Oil Alkyd (70% NVM) 292.0 
Castor Wax 2.0 
Heat Bodied Linseed Oil (80% NVM) 
80.0 
Heat Bodied Linseed/Tung Oil (54% NVM) 
21.8 
Mineral Spirits 97.8 
Organo Montmorillonite Clay 
5.0 
Methyl Ethyl Ketoxime 1.0 
Titanium Dioxide 250.0 
Zinc Oxide 100.0 
Calcium Carbonate 250.0 
Alkali Refined Linseed Oil 
124.0 
Catalyst Solution 4.0 
______________________________________ 
EXAMPLE 5 
A water borne alkyd enamel house paint is prepared by mixing the following 
ingredients in the indicated proportions: 
______________________________________ 
Kelsol 3922 (80% NVM) 
267.5 
Triethylamine 7.5 
Long Oil Alkyd (100% NVM) 
12.0 
Propoxy Propanol 26.7 
Defoamer 5.1 
Water 460.4 
ASE-60 13.1 
28% Ammonia 9.4 
Titanium Dioxide 275.0 
Catalyst Solution 2.3 
______________________________________ 
EXAMPLE 6 
A alkyd modifier for use in latex paints is prepared by mixing the 
following ingredients in the indicated proportions: 
______________________________________ 
Long Oil Alkyd (100% NVM) 
210.0 
Catalyst Solution 2.1 
Non-Ionic Surfactant 2.3 
Defoamer 1.0 
______________________________________ 
EXAMPLE 7 
An acrylic latex house paint is prepared utilizing the prepared alkyd 
modifier of Example 6 by mixing with the following ingredients in the 
indicated proportions: 
______________________________________ 
Water 125.0 
Acrylic Emulsion (50% NVM) 
431.2 
Propylene Glycol 121.0 
Coalescing Solvent 16.0 
Anionic Dispersant 10.3 
Nonionic Surfactant 3.3 
Methyl Cellulose 2.8 
Defoamer 1.0 
Fungicide 5.0 
Package Preservative 1.8 
Titanium Dioxide 275.0 
Prepared Alkyd Modifier (Example 6) 
38.0 
______________________________________ 
EXAMPLE 8 
An alkyd enamel is prepared by mixing the catalyst solution of Examples 1 
or 2 with the following ingredients in the indicated proportions: 
______________________________________ 
Medium Length Alkyd (50% NVM) 
505.8 
Long Oil Alkyd (100% NVM) 
24.0 
Castor Wax 2.0 
Organo Montmorillonite Clay 
8.0 
Soya Lecithin 4.3 
Mineral Spirits 143.3 
Methyl Ethyl Ketoxime 1.9 
Titanium Dioxide 250.0 
Catalyst Solution 2.8 
______________________________________ 
From the foregoing, it will be appreciated by those skilled in the art that 
the inventive drier catalyst is useful in any of a wide variety of 
polyunsaturated oil containing coating compositions, is useful in the 
presence of zinc compounds such as zinc salts or zinc oxide and is 
unaffected by the presence of iron in the coating composition. The 
catalyst is economical, is simple to prepare and provides excellent drying 
promotion activity. 
The foregoing detailed description is given for clearness of understanding 
only, and no unnecessary limitations should be inferred therefrom, as 
modifications within the scope of the invention will be obvious to those 
skilled in the art.