GB1562183A - Emulsifier compositions - Google Patents

Description

(54) IMPROVED EMULSIFIER COMPOSITIONS (71) We, EXXON RESEARCH AND ENGINEERING COMPANY, a Corporation duly organised and existing under the laws of the State of Delaware, United States of America, of Linden, New Jersey, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to emulsifier compositions and to uses thereof.

Oil in water emulsions are used as lubricating and cooling materials in metal working operations such as metal cutting. It is important that the oil be easily emulsifiable in the water, that the emulsion be stable, have good anti-corrosion properties and be resistant to hard water. It is therefore necessary to use an emulsifying agent and anti-rust additives are frequently included to give improved anti-corrosion.

Sulphonates are widely used as emulsifiers for many purposes, including the formation of emulsifiable lubricating compositions for use in metal working operations. For a long time petroleum sulphonates have been employed but although they are not expensive materials they have the disadvantage that they are not very constant in their quality and hence in their emulsifying properties. It has been proposed to improve the emulsifying powers of these known sulphonates by associating with them secondary surface active agents of different types, more especially non-ionic types of fatty acid salts. It has also been proposed to employ sulphonates derived from synthetic alkylarenes in place of these petroleum sulphonates.

Oils are made up of mixtures of hydrocarbons containing aromatic, naphthenic and paraffinic groups. The properties of the oil varies according to the relative proportions of each type of group which depend on the source of the crude oil from which the oil is obtained and the refining process used. For example crude oils from Venezuela which have a high aromatic and naphthenic content with a low paraffinic content are known as naphthenic oils whereas crude oils from the Middle East having a lower aromatic and naphthenic content with a higher paraffinic content are known as paraffinic oils.

As a guide but not a rule the term paraffinic oil is used to describe oils containing less than 12% carbon atoms in aromatic rings and having a ratio of carbon atoms not in rings to carbon atoms in naphthenic rings greater than 2.0 especially greater than 2.5. These oils contain more than 55 Ó of carbon atoms not in rings.

In our specification 1476891 we describe and claim an emulsifier composition comprising salts of alkylaryl-sulfonic acids and an organic or inorganic base, wherein the molecular weights of the acids from which the salts are derived are distributed according to the function C=f(M), where C denotes concentration and M denotes molecular weight of individual acids, which function has two distinct concentration maxima at molecular weights M1 and M2, with M1 less than M2 wherein there are present from 5 to 95 wt%, of salts from acids giving the concentration maximum at molecular weight M1 and 95 to 5 wit.% of salts from acids giving the concentration maximum at molecular weights M2, M1 is in the range of from 270n00 and the difference (M2-M1) is in the range 80 to 350.

Although these have been found to be particularly useful in producing emulsions of naphthenic oils in water they are not however entirely satisfactory in the production of emulsions of paraffinic oils in water.

Naphthenic oils have predominated for use in cutting oil emulsions and thus most emulsifier systems have been developed for naphthenic oils. However, in many parts of the world paraffinic oils are now more readily available than naphthenic oils and there is a need for emulsifier systems for paraffinic oils but the conventional emulsifier systems used for naphthenic oils have been found to be unsuitable in paraffinic oils.

An aim of the present invention is to provide an emulsifier system which can be used to emulsify the wide range of paraffinic oils ranging from those oils containing as little as 5% carbon atoms in aromatic rings which it has not hitherto been possible to emulsify to those less paraffinic oils containing about 12"" carbon atoms in aromatic rings.

We have now found that the addition of a small amount of a certain type of lipophilic surface active agent that is compatible with the mixtures of sulphonates described in Specification 1476891 renders the sulphonates of Specification 1476891 more suitable for forming oil in water emulsions from the range of paraffinic oils described above.

The present invention therefore provides an emulsifier composition comprising a mixture of salts of alkylaryl-sulphonic acids and an organic or mineral base, wherein the molecular weights of the acids from which the salts are derived are distributed in accordance with the function C=f (M), where C denotes concentration and M denotes molecular weight of individual acids, which function has two distinct maxima at molecular weights M1 and M2 with M, less than M, wherei-n there are present from 5 to 95 wt. ", of salts from acids giving the concentration maximum at molecular weight M1 and 95 to 5 wt. 7, of salts from acids giving the concentration maximum at molecular weight M2, in which the value of M1 is from 270 to 400 and the difference between M1 and M2 is in the range 80 to 350 and from 1% to 20% by weight of the salts of the alkylaryl-sulphonic acids of a lipophilic surface active agent which is compatible with the salts of the sulphonic acids said lipophilic surface active agent being an oxidised paraffinic wax of molecular weight greater than 500 or an ester of a fatty acid containing from 6 to 30 carbon atoms and an aliphatic polyol. The sulphonic acid salts used in invention are preferably sodium salts. However, ammonium salts, or those of the other alkali metals, or of the alkaline earth metals may be used as may salts of organic nitrogen bases such as primary, secondary or tertiary amines, polyamines and alkanolamines. The preferred organic bases are monoethanolamine, diethanolamine, triethanolamine and mixtures of these ethanolamines.

The value of M1 is preferably from 360 to 400. The preferred value of M2 is not more than 600 and more preferably from 450 to 550. It is also preferred that the difference M2-M1 is in the range 80 to 220.

The overall mean molecular weight of the alkylaryl sulphonic acids contained in the alkylaryl sulphonate portion of the compositions according to the invention is chosen as a function of the nature of the base with which they are combined and of the particular use for which the emulsifier is intended. The most favourable overall mean molecular weight depends in particular on the more or less polar character of the organic phase it is desired to disperse in water. In most cases the overall mean is between 300 and 550, preferably 300 to 500, more preferably 375 to 500.

The alkylaryl sulphonates used in the emulsifier compositions of the invention can be prepared by mixing in a suitable proportion alkylaryl sulphonates based on alkylaryl sulphonic acids whose mean molecular weight is M1 and alkylaryl sulphonates based on alkylaryl sulphonic acids whose mean molecular weight is M2. Alternatively, they can be prepared by neutralising with a base a mixture consisting of appropriate proportions of alkylaryl sulphonic acids whose mean molecular weight is M1 and alkylaryl sulphonic acids whose mean molecular weight is M2. A further possible method of preparing the alkylaryl sulphonates is by sulphonating a mixture containing appropriate proportions of aromatic hydrocarbons whose mean molecular weight is M1 -80 and aromatic hydrocarbons whose mean molecular weight is M2-80, then neutralising with a base the sulphonic acids thus obtained.

The preferred sulphonates for use in the compositions of the present invention are derived from alkylaryl sulphonic acids which have been prepared by sulphonating alkylbenzenes. By alkylbenzenes is meant the alkylation products of benzene itself: its homologues with up to 10 carbon atoms, such as toluene, xylenes, ethylbenzenes; the alkylating agent being olefins, olefin oligomers, or chloroparaffins, of appropriate mean molecular weights. It is also preferred that the alkyl groups of the alkylaryl sulphonates are branched-chain alkyl groups since these give rise to improved emulsion stability. Accordingly, it is preferred that at least a proportion of the sulphonate portion of the emulsifier composition according to this invention is made up of branched-chain alkyl compounds.

Preferably a major proportion and most preferably all of the sulphonate portion is of such compounds. Highly preferred are alkylaryl sulphonates derived from benzene and orthoxylene, especially when the alkyl groups are branched-chain, for example when propylene oligomers are the alkylating agent.

Where the lipophilic surface active agent is an oxidised paraffin wax it should preferably be of molecular weight in the range 500 to 1000, products of molecular weight lower than 500 will not result in a stable emulsion, and it should preferably be present in an amount from 1 / to 15% by weight of the mixtures of sulphonates, preferably from 2% to 7% by weight. The oxidised paraffin wax may, if necessary, be blended with other lipophilic surface active agents. The amount that should be used will depend upon the nature of the oil and the nature of the sulphonates.

Where the lipophilic surface active agent is an ester we prefer to use esters of glycerol and a fatty acid which may be any mono- or di-glyceride of a fatty acid that is compatible with the mixture of sulphonates. Examples of preferred glycerides include the mono- or di-glycerides of fatty acids containing from 10 to 20 carbon atoms. Ester of other polyols may be used providing they are aliphatic polyols.

In particular we prefer to use mono- or di-glyceride, derived from glycerol and oleic acid. The mono- or di-glycerides should preferably be present in an amount from 1% to 20 ,^ by weight of the mixtures of sulphonates, preferably 1 to 15 most preferably from 2% to 7% by weight. The amount that should be used will depend upon the nature of the oil and the nature of the sulphonate. Mono- or diglycerides are preferred since the presence of the free hydroxyl seems to improve emulsion stability as compared to using triglycerides. We also find that the glycerides are preferable to the derivatives of cyclic polyhydroxy compounds such as sorbitan since they enable stable emulsions to be obtained with a wide range of oils including highly paraffinic oils.

The emulsifier compositions in accordance with this invention give rise to unexpected advantages especially in emulsion stability particularly with emulsions of paraffinic oils in water and in many cases they are superior to those achieved using just the mixture of sulphonates. The compositions of the present invention also have the advantage that they can be prepared to be of substantially constant quality. Specifically preferred compositions are those containing sulphonates of low average molecular weight salts of C8 to C,6 alkyl (espcially branched-chain alkyl) or orthoxylene sulphonic acids, together with high molecular weight salts of C18 to C28 alkyl (especially branched-chain alkyl) benzene sulphonic acids together with 1% to 15% by weight preferably 2 to 7% by weight of a glyceride. More preferably the alkyl groups are, respectively, C,0 to C,6 and C20 to C28. Especially suitable compositions are obtained when said groups are, respectively, C,2 to C,6 and C20 to C28. In all cases it is most preferred that these alkyl groups are branchedchain alkyl groups. In all cases sodium salts are the preferred compounds.

Normally it will be found that since the alkylaryl sulphonates are highly viscous materials and, accordingly, the compositions of the present invention are advantageously diluted either in manufacture, or thereafter, with a suitable diluent/solvent, such as a hydrocarbon oil of the light lubricating oil type. The invention includes within its scope concentrates containing 50 to 95 wt. /O of the emulsifier composition and 50 to 5 wt. % of a solvent/diluent, such as light lubricating oil, for example one having a viscosity of 20 to 40 cSt at 400C.

In accordance with a further feature of the invention there is provided an emulsifiable mineral oil composition containing a mineral oil and an emulsifier composition as described above. Suitable mineral oils are those having a viscosity of from 5 to 100 cSt at 400C. Although the compositions of the present invention have especial advantages in paraffinic oils they may also be used with other oils such as naphthenic oils.

It is important that the emulsifier compositions of our invention do not promote rusting when they are used in cutting oils so they generally contain an antirust agent or anticorrosion agent. Traditional antirust agents may be used such as the salts of tall oil fatty acids especially the amine salts.

The present invention also provides a cutting oil for metal working, based on mineral oil, especially a paraffinic oil, whose viscosity is between 5 and 100 cSt at 40"C, containing from 1 to 5% by weight of one or more extreme pressure lubricating agents, from 1 to 5% by weight of one or more anti-corrosion agents and from 0.1 to 3 by weight of one or more bactericidal agents and from 10 to 500,; by weight of the emulsifier compositions of the present invention. Many emulsions tend to foam when used particularly as cutting oils and thus an antifoam agent such as a silicone may be included in the formulation. The antifoam agents may be the commonly used silicones and are generally present as from 0.05 ,' to 20/ by weight of the emulsifier system.

We have found that the emulsifier systems of our invention may be used to emulsify a wide range of mineral oils and are particularly useful for emulsifying the paraffinic mineral oil containing less than 120/fl,, or less than 8% carbon atoms in aromatic rings, and having a ratio of carbon atoms not in rings, carbon atoms in naphthenic rings, more than 2 which have hitherto been difficult to emulsify.

By dispersing this cutting oil in water, a stable aqueous emulsion for metal working is obtained. This emulsion is likewise covered by the scope of the present invention and may contain 90 to 99 by weight ,', suitably 95 to 98 by weight ' water.

The following non-limitative examples illustrate features of the invention. All proportions referred to in these examples are calculated by weight. In these Examples the hardness of the water is given according to the standard French scale known as the "Titre Hydrotemetric" (given as "OTH") Example 1 An emulsifier system comprising 44% by weight of a sodium alkylbenzene sulphonate of molecular weight 520 and 28% by weight of a sodium alkylbenzene sulphonate of molecular weight 380, 13% by weight of butyl Cellusolve (Registered Trade Mark), the remainder being water and a standard anti-rust material was found to successfully emulsify a naphthenic oil of density 0.903, viscosity at 37.8"C of 20.8 centistokes and 3.7 centistokes at 98.9oC. The infra red analysis of this oil showed 21.2% of the carbon atoms to be in aromatic rings, 53.2% of the carbons not to be in rings and 25.6% of the carbons atoms to be in naphthenic rings. It was found that using 80 ' by weight of this oil and 20% by weight of the emulsifier system that a 5% oil in water emulsion would be formed in 7 minutes and that a small ring of cream was formed at the top of the oil/water emulsion after storage in a closed container for 7 days.

The emulsifier system described above could not however be used to emulsify either of the following oils.

Oil A OilB Flash Point 214 C 188"C Viscosity at 37.80C 31 15.6 at98.9 C 5.18 3.44 Density 0.867 0.848 Infra Red E Carbon atoms in aromatic rings 7.5 6.7 % Carbon atoms not in rings 65.1 66.9 z Carbon atoms in naphthenic rings 27.4 26.4 Example 2 80 parts of the Oil A and Oil B of Example 1 were mixed with 20 parts of the emulsifier systems designated 1, 2 and 3 below: Emulsifier 1 2 3 Sodium Alkylbenzene Sulphonate Molecular Weight 520 58 57.3 56.9 Sodium Alkylbenzene Sulphonate Molecular Weight 380 14 14.6 15.1 Oxidized Paraffin Wax 3.9 3.7 3.6 Butyl Cellosolve (Registered Trade Mark) 9.1 9.3 9.4 Anti-rust Agents 10 10 10 Water 5 5 5 In System (I) the anti-rust agent was an ammonium salt of a carboxylic acid whilst in Systems 2 and 3 the agent was a blend of the same ammonium salt with an amide.

Each of the emulsifier systems described above was prepared using the following three different oxidised paraffin waxes: Oxidised Paraffin Wax (a) (b) (c) Molecular Weight 700 730 300 Acid No. (mg KOHg) 47 50 74 Saponification No. 109 110 147 Density at 15 C 0.95 0.95 0.975 Viscosity at 98.9 C 71 - 16 Fusion Point 57 C 53 C 20 C In all instances it was found that when using the oxidised paraffin waxes (a) and (b) a satisfactory stable emulsion was obtained with good anti-rust properties.

However, when using the oxidised paraffin wax (c) it was not possible to obtain a good emulsion.

The emulsion stability was measured by introducing the emulsifiable oil into a stirred water, stirring the mixture for 1 minute and then transferring to a graduated 100 cc test tube and noting the flotation after 7 days. The rate of emulsification was measured by placing 95 cc's of water and 5 cc's of the emulsifable oil in a test tube which is rotated at -16 half turns per minute and taking the time for complete emulsification. The anti-rust properties were measured by the Herbert test (British Standard IP 123-63) in which steel shavings are placed on a cleaned cast iron plate and 2 cc's of the emulsion poured onto the shavings. The shavings are removed after 24 hours and the surface of the plate examined and three readings taken: (i) the number of pittings (ii) the extent of the rusty surface (iii) the intensity of the rust, 0 being no rust and 4 denoting a damaged surface Example 3 The emulsifier system 1 used in Example 2 with oxidised Paraffin wax 6 was used with several different paraffinic oils none of which could be successfully emulsified using solely the mixture of sulphonates as the emulsifier system. In each instance 20% by weight of emulsifier on the weight of the oil was used and 5% by weight of oil was emulsified in water. With all the oils the emulsion stability was such that less than 0.59/, by weight of cream formed after 7 days.

The following oils were used: Infra Red Analysis Viscosityat37.8 C Densityat /OCarbonsln Naphthenic Rings in Rings Centistokes 15 C Aromatic Rings 25.9 64.5 27.3 0.871 9.6 26.2 66.0 22.3 0.867 7.8 22.8 66.2 21.0 0.863 11.0 24.8 64.2 21.0 0.874 11.0 27.8 63.8 20.8 0.870 8.4 Example 4 An emulsifier system similar to that of Example 2 was prepared containing 4% by weight of the commercially available UNEM (Registered Trade Mark) 4113 and 20 wt. % of this system was incorporated into the following oils: Viscosity at Density at % Carbons in % Carbons in % Carbons 37.8 C(Centistokes) 15 C Aromatic Rings Naphthenic Rings 'Not in Rings 20.9 0.861 5.5 26.5 66.0 22.5 0.860 6.5 26.5 67.0 15.6 0.848 6.7 26.4 66.9 22.8 0.865 7.0 29.5 63.5 22.1 0.875 9.0 30.0 61.0 21.0 0.870 9.0 27.0 64.0 20.0 0.860 10.0 26.0 64.0 20.6 0.865 11.0 26.0 63.0 5% of these oils were emulsified in various waters up to hardness 50 TH and in each instance an emulsion was formed in less than 10 minutes and was stable for 7 days. For all oils sufficient antirust properties were achieved using less than 2% of the oil in water.

Example 5 The emulsifier system used in Example 4 was used to emulsify five different oils, 20 wt. a of the emulsifier system based on the weight of the oil was used to give a 5 vol. " oil in water emulsion. The emulsability, emulsion stability and corrosion properties were determined using the tests of Example 2, the result given for the corrosion test is the volume Ma of oil containing the emulsifier system based on the volume of water required to give a test reading of 0/0-0.

The results were as follows: Base Oil (4;Carbon atoms in Aromatic rings 5.2 5.4 6.8 8.9 27.1 ," Carbon atoms not in rings 68.1 66.0 63.5 61.3 59.6 % Carbon atoms in Naphthene rings 26.7 28.6 29.7 29.8 13.3 Viscosity at 37.80C 9.5 20.9 22.8 22.2 20.7 Specific Gravity 0.837 0.858 0.864 0.875 0.890 Emulsibility (seconds 400 360 320 380 390 Emulsion Stability (tap water) 1 day 0.5 ml cream Ring Ring Ring Ring 7 days 1 ml cream Ring 0.5 Ring Ring Herbert Test 1.5 1.5 1.5 1.5 1.5 WHAT WE CLAIM IS: 1. An emulsifier composition comprising a mixture of salts of alkylarylsulphonic acids and an organic or mineral base wherein the molecular weights of the acids from which the salts are derived are distributed in accordance with the function C=f(M) where C denotes concentration and M denotes molecular weight of the individual acids which function has two distinct maxima at molecular weights M, and M2 with M1 less than M2 wherein there are present from 5 to 95 wt. % of salts from acids giving the concentration maximum at molecular weight M1 and 95 to 5 wt.% of salts from acids giving the concentration maximum at molecular weight M2 in which the value of M1 is from 270 to 400 and the difference between M, and M2 is in the range 80 to 350 and from I % to 20% by weight of the salts of alkylarylsulphonic acids of a lipophilic surface active agent which is compatible with the salts of the sulphonic acids said lipophilic surface active agent being an oxidised paraffin wax of molecular weight greater than 500 or an ester of a fatty acid containing from 6 to 30 carbon atoms and an aliphatic polyol.

2. An emulsifier composition according to Claim 1 in which the value of M2 is from 350 to 600.

3. An emulsifier composition according to Claim 1 or Claim 2 in which the lipophilic surface active agent is present in an amount from 1% to 15% by weight of the mixture of sulphonates.

4. An emulsifier composition according to any of Claims I to 3 in which the lipophilic surface active agent is an ester of a fatty acid containing from 10 to 20 carbon atoms and an aliphatic polyol.

5. An emulsifier composition according to Claim 4 in which the aliphatic polyol is glycerol.

6. An emulsifiable mineral oil comprising a mineral oil containing from 10"" to 500;;, by weight of an emulsifier composition according to any of the preceding

Claims (1)

1. claims.

   7. An emulsifiable mineral oil according to Claim 6 in which the mineral oil contains less than 8% of carbon atoms in aromatic rings.

   8. A concentrate containing 50 to 95 wt. % of an emulsifier composition according to any one of Claims 1 to 5 and 50 to 5 wt. o, of a solvent or a diluent.

   9. A cutting oil for metal working comprising mineral oil containing from 1"" to 5% by weight of one or more extreme pressure agents, from 1% to 5% by weight of one or more anti-corrosion agents, from 0.1 to 3% by weight of one or more bactericidal agents and from 10 to 50% by weight of an emulsifier composition according to any one of Claims 1 to 5.

   10. A cutting oil according to Claim 9 in which the mineral oil contains less than 12 ,', of carbon atoms in aromatic rings and has a viscosity between 5 and 100 cSt at 400C.

   11. An emulsifier composition according to Claim 1, substantially as hereinbefore described with particular reference to Examples 2 to 5.

   12. An aqueous emulsion containing from 90 to 99% by weight of water and from 10% to I %, by weight of an emulsifiable mineral oil according to Claim 6 or Claim 7.