Synthetic emulsifiers and their use

Salts of sulphonic acids of high molecular weight with alkyl groups derived from normal olefins, preferably normal C.sub.3 to C.sub.6 olefins and more preferably normal butene are used as emulsifiers in oil water systems particularly in oil in water emulsions such as microemulsions and white or milky emulsions.

The present Invention relates to the use of salts of alkyl aryl sulphonic 
acids as emulsifiers in oil water systems in which the alkyl group of the 
aryl sulphonic acid is derived from one or more normal olefines and the 
molecular weight of the alkyl aryl sulphonic acid is greater than 530. 
The sulphonic acids may be neutralised to form sulphonates for use as an 
emulsifier or in oil recovery the cation will generally be an alkali metal 
or a quaternary nitrogenic cation. 
Emulsified oils are now used in a large number of machining operations due 
to an industry demand for higher production rates, lower costs, improved 
environmental conditions and better operator acceptance. Emulsions are 
generally used where cooling is more important than lubrication. In 
operations such as broaching, deep drilling, or where surface finish is 
particularly critical, neat oils may still be used, but the development of 
extreme pressure additives in emulsions has increased their applicability 
and use. 
The emulsions are generally prepared from emulsifiable oils supplied to the 
final user for incorporation into the water. The emulsifiable oils 
frequently contain additives which can be supplied as an additive package, 
formulation or concentrate to the producer of the emulsifiable cutting 
oil. 
Amongst the various types of fluids, there is a marked trend towards those 
having an optimised combination of lubricating, cooling and long-life 
properties. Such fluids are obtained by micro-emulsification of a base oil 
formulated with anti-corrosion and biostability agents. The micro-emulsion 
type of cutting fluid has good stability due to the very small size of 
their hydrocarbon droplets which do not tend to coalesce during storage. 
This feature is a key advantage over conventional fluids forming white 
emulsion whose hydrocarbon droplet size is much larger, where formulation 
with water-soluble biostability agents is difficult. 
Aqueous metal working fluids have been known for many years and different 
additives have been developed to provide oils useful for different types 
of metal working and for use with different types of water. 
Various emulsifiers have been proposed for the production of water in oil 
and oil in water emulsions. Typical emulsifiers are the sulphonates, such 
as the natural and synthetic petroleum sulphonates and the synthetic alkyl 
aryl sulphonates, such as the C.sub.12 -C.sub.24 alkyl benzene and toluene 
sulphonates and mixtures thereof as described in United Kingdom patent 
specification 1476891. These sulphonates are typically derived from 
sulphonic acids which have average molecular weights of 530 or less. 
The aqueous metal working fluids may be water in oil emulsions or oil in 
water emulsions, largely depending upon whether lubrication or cooling is 
the more important. We are, however, particularly concerned with the 
currently more popular oil in water emulsion cutting fluids such as 
microemulsions and white or milky emulsions. 
The additives may be supplied to a producer of emulsifiable oils or to the 
producer of the aqueous fluids. In either instance they may be supplied as 
a solution or an emulsion of the sulphonates together with other additives 
for incorporation into oil or the bulk of the water. The solution may be 
in oil or water and if in oil it will generally contain some water. 
The emulsifiable oil supplied to the final user may contain other 
emulsifiers to enable the production of oil in water or water in oil 
emulsions and, the choice depending upon the nature of the oil and the 
type of emulsion required. Alternatively the final user may introduce the 
emulsifier into the fluid separately. Salts of the synthetic alkyl benzene 
sulphonic acids, particularly the mixtures which-form the subject of 
United Kingdom Patent No. 1476891 are our preferred co-emulsifier, other 
suitable emulsifiers are the sulphonamide carboxylates such as those 
described in French Patent 2403396 and the sulphonates described in 
European Patent Application 0015491. 
We have found that by using sulphonic acids of high molecular weight with 
alkyl groups derived from normal olefines, preferably normal C.sub.3 to 
C.sub.6 olefines and more preferably normal butene, the performance of the 
salts as emulsifiers is significantly improved compared to conventional 
alkyl aryl sulphonate emulsifiers which are based on sulphonic acids of 
low molecular weight with alkyl groups derived from branched olefines and 
of thus enabling comparable emulsions to be obtained using a smaller 
amount of emulsifier. Whereas when using a conventional emulsifier 11 mass 
% or more has typically been required for the production of stable 
emulsions we have found that emulsions of comparable stability may be 
obtained using less than 11 mass % and surprisingly even at less than 5 
mass % of emulsifier according to this invention. The alkyl aryl sulphonic 
acids used to prepare the emulsifiers of the present invention have an 
average molecular weight of greater than 530, preferably 630 or greater 
and most preferably 660 or greater. It is preferred that the average 
molecular weight is in the range of 530 to 1200 and most preferably in the 
range 630 to 1200. 
We therefore prefer that the emulsifiable cutting oil for incorporation 
into bulk water contains from 2to 80 wt %, preferably 3 to 25 wt %, and 
more preferably 7 to 20 wt % of the emulsifier. The emulsifiable cutting 
oil may be incorporated into bulk water at 2 to 30 mass % preferably 2 to 
20 mass %. 
Where fluids are to be used for metal working they may be boron free 
although small amounts of boron may be required for the necessary 
anti-bacterial properties. Boron may be provided by incorporating boric 
acid or any other boron compound that forms boric acid upon being 
dissolved in water, such as metaboric acid or boric oxide. It is believed 
that the boric acid forms an addition product or salt with the amine which 
is a syrupy liquid and does not precipitate out of the cutting fluid. The 
emulsifiable oil may contain up to 30 wt % boric acid although we prefer 
that it contains from 2 to 6 wt % of boric acid to give no more than 1.0, 
preferably no more than 0.4 wt % boron in the final aqueous metal working 
fluid. 
Other additives which may be present include hydroxy di- or tri-carboxylic 
acids which may be used are tartaric and citric acids. It is important 
that the acid used be soluble in water. 
Alkanolamines used in the present invention may also be present in cutting 
oil formulations using the sulphonates of the present invention, typically 
those which contain from one to three aliphatic radicals, each containing 
from one to four carbon atoms, and have at least one hydroxy group 
attached to a carbon atom, and include primary, secondary and tertiary 
alkylol amines such as mono-di- or triethanolamine. We prefer that both 
the emulsifiable oil and the aqueous fluid contain an excess of 
alkanolamine relative to total acid content. 
A coupling agent such as a non-ionic wetting agent is generally used in 
aqueous metal working fluids embodying the invention. To improve the 
compatibility of the components, any desired non-ionic wetting agent may 
be used, such as a condensation product of ethylene oxide, a condensation 
product of a fatty acid or derivative, such as a derivative of a fatty 
acid, fatty alcohols, fatty amide or fatty amine, with ethylene oxides and 
a reaction product obtained by the condensation of an oxyalkylaryl 
compound, such as a derivative of an alkylphenol or alkylnaphthol, with 
ethylene oxide. It is preferable that the non-ionic wetting agent employed 
be water-soluble. Typical non-ionic wetting agents include the 
polyethoxyesters of fatty acids, the monooleate of a polyethylene glycol, 
the monolaurate of a polyethylene glycol, the polyethoxyethers of fatty 
alcohols, the condensation product of an alkylphenol such as dodecyl 
phenol with 12 moles of ethylene oxide, and the sulfonated product of the 
condensation of an alkylphenol or an alkylnaphthyl with ethylene oxide. 
A particularly useful non-ionic wetting agent is an alkyl phenoxy 
polyethyoxy ethanol such as octyl or nonyl phenoxy polyethoxy ethanol. 
We also find, particularly when emulsifiers other than sulphonic acids and 
sulphonates are used that carboxylic acids such as neo acids and fatty 
acids such as tall oil fatty acid may be included to enhance emulsion 
production. 
Other ingredients which may be incorporated in the aqueous fluids include 
silicone and/or silicone free anti-foaming agents and biocides. 
Neutral sodium sulphonates obtained from these sulphonic acids were used as 
emulsifiers for cutting oils. The cutting oils are obtained by blending 
the sodium sulphonate with or without a co-emulsifier, with a coupling 
agent and by blending the mixture with a base oil. Other co-additives can 
be introduced to the cutting oil include: corrosion inhibitors, 
white/yellow metal passivators, defoamers, extreme-pressure, antiwear or 
lubricity agents, biocides or biostatic agents, additives yielding 
alkalinity reserve.

Emulsions were prepared to compare the stability of emulsions according to 
the present invention and those using conventional emulsifiers. The target 
was to determine the minimum amount of sodium sulphonate required to 
produce a stable translucent micro emulsion. The results were as follows: 
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Comparative 
Mass % Example Example 1 
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Anti-corrosion additive* 
44.7 45.0 
Water 30.5 37.3 
Tall Oil Fatty Acid 1.8 2.0 
Butyldiglycol 4.2 2.0 
Sodium Salt of (polynormalbutyl)benzene 
-- 4.7 
sulphonic acid.** 
Mixed alkyl benzene sulphonic acid of average 
11.3 -- 
molecular weight of 530.** 
90 Neutral Oil 7.5 9.1 
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*The anticorrosion additive is a proprietary additive package comprising 
boric acid, alkanolamine, hydroxy carboxylic acid and water. 
**Both of the emulsifiers were used as approximately 60% active ingredien 
solutions in oil. 
The results in the table clearly show that the emulsifier derived from 
polynormalbutyl benzene sulphonic acid is able to provide a stable 
microemulsion at less than half the concentration of a conventional 
emulsifier. Furthermore it is able to do this with a larger amount of oil 
and with the use of significantly lower levels of butyidiglycol coupling 
agent compared to the conventional emulsifier.