CA1061321A

CA1061321A - Metal-working lubricants

Info

Publication number: CA1061321A
Application number: CA244,871A
Authority: CA
Inventors: Edward J. Bates; Brian A. Cook
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1975-02-06
Filing date: 1976-02-03
Publication date: 1979-08-28
Also published as: DE2604710A1; FR2300128B1; GB1521081A; JPS51103107A; FR2300128A1

Abstract

ABSTRACT

Compositions suitable for the manufacture of aqueous metal working lubricant emulsions contain a tetra-ester of pentaerythritol and a non-ionic emulsifying agent which is the condensation product of an alkyl phenol and ethylene oxide.
Desirably, phosphoric acid is also present. Aqueous emulsions made from such compositions have high stability, low friction value and good-load-carrying properties. The emulsions are especially suited for use as lubricants in rolling steel or aluminum. When a higher friction value is required, and when acceptable in the process concerned, a quantity of mineral lubricating oil may also be present.

Description

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The present invenfion relate~ to metsl-working lubricants and procesa employing those lubrîcants, and i3 especially concerned with lu~ricants for metal rolling and for aluminium ca~ting and concastin~.
In rolling operationa to produce 1at me~al product~ the metal stock 19 inserted between two converging roll surfaces, which deform the metal while advancing the metal between them. U~ually it is nece~sary to provide the roll-metal interace with a rolling liquid. The~e rolling liquid~ Aerve to lubricate snd 90 minimise pick-up of strip metal on the rolls, while at the same tima maintaining an adequate coeficient of friction at the point of rolling to permit the prope~ rate o metal deformation and the reduction required. Another lmportant unction of the rolling liquid is to cool the roll~ and thu~ dissipata the hea~ generated during the rolling operation.
Tha choice o a suitable rolling liquid is essential to the satisactory parformnnce of the rolling operation. Thus, iE the lubrication is excessive~
the rollA will slip and the surace of the strip being rolled will be disadvantageoualy aectad. On the other hand, if the lubrication i9 in~uÇiclent the required reduction cannot ba obtained. Likewi~e, the coollng efect of the rolling li~uid i~ important since inadequate cooling ofton results in metal plate of uneven thickness.
The rolling li~uids which are now being used in practice may be oP the homogeneou9 or non-emul~iiable type such a9 ~traight mineral oils, atty 0118 or compounded oil9 consisting o a mineral oil and A fstty oil; or they may be ~n ~mul9ion of ~n oil, u~ally a min&ral oil, in watar. The salection o the particular type of rolling liquid depends upon the nature oE the metal to be procea~ed and the conditions of the rolling operation.
For cold rolling of steel, copper and brass, both homogéneous and emul~ion typa liquidA may be u~ed. In the hot rolling of aluminium, emulsion type ~, . ......................... ..
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rolling liquids are used. In cases where emulsion type rolling liquids can be used these are usually preferred over the non-emulsifiable rolling liguids because of their superior cooling properties, which allow faster production speeds to be obtained.
However,:the rolling emulsions also have certain disadvantages. It is u~ually difficult to prepare emulsions with good reduction and friction properties whilst also pos3essin~ good emulsion stability. Often there occurs during storage some phase-separation, which can cause a product of variable composition to be ~upplied to the rolls, and make the product physically difficult to filter free from me~al~ ines.
The main requirements of a~ emulsion for use in cold rolling of steel or hot rolling of aluminium are, therefore, high emulsion stability, cou~led with good friction value and good load-carrying properties.
It is an object of the present invention to provide an emulsifiable composition which, on emulsification, gives an emulsion having improved properties (for example high emulsion stability and good friction value), especially when employed as rolling lubricants and more especially as a lubricant in the cold rolling of steel or the hot rolling o aluminium.
According to the present invention there is provided an emulsifiable concentrate suitable for the preparation of an aqueous emulsion suitable for use in metal working ~especially metal rolling and aluminium ~castïng and concasting), which concentrate comprises at least one tetraester of pentaerythritol and a C12 to C22 aliphatic monocarboxylic acid and a total of from 5 to 25%, preferably 10 to 20% (by wt.% of total tetraester) of at leas~ one non-ionic emulsifier as hereinaf~er defined. Preferably the tetraester employed is liquid at normal temperatures and pressures; however solid . ' : ' : ~ r ~C~6~3Z~

esters such as pentaerythritol tetrastearate and palmitate may be considered.
The said aliphatic monocarboxylic acid is preferably an unsaturated acid, mo~t preferably mono-ethylenically unsaturated. C16 ~o C20, particularly C16 to Clg, acids are preferred. Thus a highly preferred liquid tetraester is pentaerythritol tetraoleate. Such a compound may be derived from a technical or from a substantially pure grade of acid.
However, by technical grade is me~nt one which predominantly comprises the acid in question. Thus although, for example, oleic acid is present in tall oil the latter contains a predominating amount of other acids~ including Clo : -and below and phenanthrene ring compounds such a~ abietic acid. These other acids render tall oil unsuitable for use in the present invention.

The pentaerythritol rom which the tetraester is derived may be su~btantially pure or a technical grade containing dipentaerythritol.
The non-ionic emulsifier(s) employed in the concentrates of this invention are product(s) of the reaction of 1 mole of an alkyl phenol containing from 10 to 25 carbon atoms per molecule with from 3 to 20 moles (preferably 3 to 12 moles, ~ost preferably 5 to 12 moles) in total of one or more alkylene oxides. Suitably, the alkylene radical contain~ 2 to 8, preferably 2, 3 or 4 carbon atoms. Ethylene oxide is the preferred oxide. Propylene oxide or a mixture of ethylene and propylene oxides may be employed, if desired.
The preferred non-ionic emulsifiers are those obtained from an alkyl phenol in which the alkyl group contains rom 6 to 18 carbon atoms.
Preferred emulslfiers are the products from the reaction of 1 mole of a C6 to Clg alkyl (more preferably C8 to C12 alkyl, most preferably nonyl) phenol and from 3 to 12 moles (preferably 5 to 12 moles) of ethylene oxide.

i ~6~321 One especially preferred product is that from the reaction of 1 mole of nonylphenol with 6 to 8 moles of ethylene oxide.
If desired, more than one said emulsifier can be used. One advantageous blend is of nonylphenol/ethylene oxide products such that there is an average between 7 and 8 mole~ of ethylene oxide per mole of alkyl phenol.
In order to increase load-carrying properties (of the eventual emulsion) the concentrate may include a minor amount of one or more ~uitable water-soluble or water-di6persible phosphorous-containing compounds.
Examples of such compounds are water-soluble or dispersible oxides of phosphorous, phosphorus acids, and alkyl phosphates in which the, or eacp, alkyl group contains 1 to 4 carbon ato~s. Orthophosphoric acid is one preferred compound. Normally the compound will be present in total amount o~ ~rom 0.01 to 0.5 wt.% (calculated a~ pho~horus) ba~ed on the total weight of tetraester. Preferably the lower limit of the ran8e is 0.02 or 0.03 wt.%, more preferably 0.07 wt.%, but may be as high as 0.1 wt.%.
Preferably the upper limit of the rang~ iB 0.3 wt.%, more preferably 0.2 wt.%. From 0.02 to 0.2 wt.% is one suitable broad range; 0.07 to 0.2 wt.~ bsing a preferred range.
Nhere a compound such as orthophosphoric acid i9 employed together with an ester such as pentaerythritol tetraoleate some reaction might occur to give phosphate esters. Any such reaction products are included in the scope of this invention as chemically equivalent to the pentaerythritol ester plus acid.
The invention further includes aqueous metal working emulsions containing a major proportion by vol. of water whether prepared from the concentrates described above, or whether prepared from the individual components of the concentrate and in the same relative amounts as ~herein.

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Normally, aqueous emulsions will contain at least 90 vol.~ water, ~uitably at least 95~. From 0.5 vol.~ to 2 vol.% or to 3 vol.% of said concentrate, or total o the components thereof, i5 a preferred range; water normally constituting the balance or substa~tially the whole of the balance.
Components such as oleic acid and an alkanolamine may be pre~ent in the concentrate or emulsion. For example up to 10 wt.% (suitably about 5 wt.%) of oleic acid and up to 6 wt.% (suitably about 3 wt.%~ o an alkanolamine may be present in the concentrate (al? wts. being based on total oE ester plu9 emulsifier). The proportionately smaller quantity may be present in the emulsion. The preferred al'kanolamine is triethanolamine;
others suitable being ethanolaminè, 2-amino-1-propanol, 3~amino-1-propanol and 2-amino-1-butanol.
A petroleum sulphate and/or fatty amide and/or a defoamant can also be employed, in conventional amounts. The defoamant will be, preferably, the known wax compound(s) type.
Still further, the invention includes metal working processes, especially metal-rolling processes an~ alum~nium casting and concasting processes, whenever conducted with an emul8ion as aforede~cribed as the, or a, iubricant.
The present invention enables the known lubricating properties of a tetr~e8ter base oil to be taken advantage of, but in the novel form of an emul~ion. Prior to the present invention it had been found that it was very difficult to successfully emul~ify a tetraester such as pentaerythritol tetra~leate. Many known emulsifiers were totally unsatisfactory9 whilst others gave rise to very unstable emulsions. A further, unexpected, benefit resulting from the invention i~ that, contrary to the hi8h frlction values sssociated with emulsion of high stability, the emulsions .

-~613Zl of the pre~ent invention have very low friction values, and high load-carrying values. Indeed, if desired, the friction value can be increased by incorporating an amount into the concentrate or emulslon of a mineral oil of normal lubricating quality and viscosity, such a~ a refined lubricating oil of viscosity 20 to 12~ cSt ~t 100F and 8 VI from 40 to 120. A wide variation in proportions is possible but, in a mix wi~h a concentrate, at leas$ lO wt.% of the mix should be the concentrate.
A petroleum sulphonate will advantageously be employed when the larger quantitie~ of mineral oil are prese~t.
It ha~ been found advantageous, and forms a feature of thi~ invention, to heat ~to from 70 to 85C, for example 80C) for a time (for example 10 to 20, suitably 15 minutes) the concentrate components, either when the concentrate is initially ormulated or just prior to its use in preparing an aqueous emulsion. The emulsion thus formed is of even 8reater stablilty.
The following Examples illustrate aspects of the invention:-~PE.E~
A series of 2 vol.% emul~ions in water were made from concentratescontaining 97.5 wt,% of commercially available pentaerythritol tetraoleate, 0.5 wt.Z of orthophosphoric acid and 2 wt.% of emulsifiers as shown in the followin8 Table. The stability of the resultant emul~ions were observed and are shown in the Table 1.

~ ~6132~ -Type of Emulsifier Stability of Emulsion Sorbitan Trioleate Very unstable Polyoxyethylene sorbitol hexaoleate Un3table - slight dispersion Polyoxyethylene Eatty glyceride ~n3table - some dispersion Alkylaryl Sulphonate Un~table - completely Polyoxyethylene esters/alkylaryl sulphonate blend Unstable - some dispersion Polyoxyethylene ether alcohol (6 mol) Partial stability ~ Moderate only Polyoxyethylene ether alcohol (12 mol) Fair stability Polyoxyethylene tridecyl ether alcohol (6 mol) Unstable - completely Polyoxyethylene sorbitan monooleate (20 mol) Partial ~tabilit~ - moderate only Polyoxyethylene monooleate (6 ~ol) Unstable - slight dispersion Polyoxyethylene nonyl phenol ether (5 mol) Par~ial Stability - moderate only " "" (6 mol) Fairly good stability " " " " (8 mol) Very good emulsion stability " " " " (9 mol) Good emulsion ~tability " " " " (12 mols) Fairly good 3tability Sodium Petroleum Sulphona~es Unstable - some dispersion Triethanolamine oleate Unstable In the Table the n~mbers re~er to the number of molecules of ethylene oxide reacted with one molecule of other reactant.
From the above Table it will be seen ~hat many type~ of emulsifier, including closely related alkylene oxide condensates, are completely unsuitable, or at best give only moderate emulsion stability. Emulsifiers in accordance with the invention, however, give good to excellent results.
The above tests were cond~cted with only 2% by wt. o~ emulsifier in the concentrate. This iB a much smaller quantity than will be employed in practice but was cho~en as a suitable level for comparative 3creening tests.

Some data on properties of two emulsions according to the invention and on properties of comparative materials are tabulated in Table 2 below.
Two concentrate formulations A and B were prepared having ~he following constitutents:
A B

Pentaerythritol tetraoleate 85 85 Orthophosphoric acid Nil 0.2 Polyethylene oxide (6 moles) 5 5 nonyl phenol ether Polyethylene oxide (8 moles) 10 10 non~l phenol ether .. . . . .. . .. . . ~

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The two concentrates were then used to orm two aqueous emulsions ~97 vol.% water) A and B . The comparstive materials, denoted C, D, E and F were respectively (all 100%) a standard mineral white oil, a solvent ex~racted mineral oil, refined rape-seed oil. The comparative materials denoted C , D , E and F were aqueous emulsions (97 vol.% water) of C, D9 E and F
respectively.
It can be seen from Table 2 that only the emulsions Al, and Bl give the required high emulsion stability coupled with good friction value and good load-carrying properties. The emulsions Cl, and Dl have a very low stability index and a very high coefficient of riction. It was not possible to obtain a meaningful result in the scuffing load test because o the very poor emulsion stability. Although for emulsions El and Fl the coeicient of riction is lower and the stability index higher, nevertheless the emulsions are still not sufficiently stable to permit a meaningul result to be obtsi~ed in the scuffing load test. The emulsions Cl, Dl, E and F are quite useless for industrial use.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An emulsifiable concentrate for the preparation of an aqueous metal working emulsion, comprising at least one tetraester of pentaerythritol and a C12 to C22 open-chain, aliphatic monocarboxylic acid and a total of from 5 to 25% (by wt. of the total tetraester) of at least one non-ionic emulsifier which is the product of the reaction of 1 mole of an alkyl phenol having from 10 to 25 carbon atoms per molecule with from 3 to 20 moles in total of at least one alkylene oxide.

2. A concentrate as claimed in claim 1, wherein the said emulsifier content is 10 to 20%.

3. A concentrate as claimed in claim 1 further containing a total of from 0.01 to 0.5 wt% (calculated as phosphorus) based on the total wt. of tetraester of at least one water-soluble or inter-dispersible phosphorus containing compound.

4. A concentrate as claimed in claim 3, wherein the said amount is 0.07 to 0.2 wt%.

5. A concentrate as claimed in claim 3 wherein the compound is orthophosphoric acid.

6. A concentrate as claimed in claim 1, further containing a quantity of a mineral lubricating oil.

7. A concentrate as claimed in claim 1, wherein the said aliphatic monocarboxylic acid is monoethylenically unsaturated.

8. A concentrate as claimed in claim 7, wherein the acid is oleic acid.

9. A concentrate is claimed in claim 1, wherein the non-ionic emulsifier is the product of the reaction of 1 mole of said alkyl phenol with from 3 to 12 moles of said alkylene oxide.

10. A concentrate as claimed in claim 1, wherein the alkyl phenol is a C8 to C12 alkyl phenol

11. A concentrate as claimed in claim 10, wherein the alkyl phenol is nonyl phenol.

12. A concentrate as claimed in claim 1, wherein the said alkylene oxide is a C2 to C4 alkylene oxide.

13. A concentrate as claimed in claim 12, wherein the alkylene oxide is ethylene oxide.

14. A concentrate as claimed in claim 1, comprising pentaerythritol tetraoleate and a total of from 5 to 25% by wt. of the tetraoleate, of at least one non-ionic emulsifier which is the product of the reaction of 1 mole of nonyl phenol with from 5 to 12 moles of ethylene oxide.

15. A concentrate as claimed in claim 14, further containing from 0.07 to 0.2 wt%
(calculated as phosphorus) based on the tetraoleate of orthophosphoric acid.

16. An aqueous metal working lubricant comprising an emulsion of a major proportion by volume of water and a minor proportion by volume of the components which are, and which have the relative proportions defined in claim 1.

17. An aqueous metal working lubricant as claimed in claim 16 containing at least 95 vol % of water.

18. A method of rolling aluminium or steel which comprises the step of lubricating the aluminum or steel with A lubricant claimed in claim 16.