CA2022914A1

CA2022914A1 - Hydraulic fluids

Info

Publication number: CA2022914A1
Application number: CA002022914A
Authority: CA
Inventors: Dieter Balzer
Original assignee: Huels AG
Current assignee: Huels AG
Priority date: 1989-08-10
Filing date: 1990-08-08
Publication date: 1991-02-11
Also published as: DE59002288D1; DE3926397A1; EP0412271B1; EP0412271A1

Abstract

ABSTRACT
Flame resistant aqueous hydraulic fluids which contain 5 to 30% by weight of alkylpolyglycoside of the formula R-O-Zn wherein R represents an alkyl radical having 8 to 20 carbon atoms and Zn represents an oligoglycoside radical having, on the adverage, 1 to 10 hexose or pentose units or mixtures thereof.
The fluids further contain up to 20% by weight of surfactant additives and up to 10% by weight of other customary additives.
The novel fluids are ecologically safe and have good lubricating properties at low concentrations of active ingredient.

Description

r, D. ~a!~r 2~229~
- FE~ ~
Tel.4701 /p~ o,z. 4410 H~LS AXTIENGESELLSCHAFT
- PATENTABTEILUNG -Hydraulic fluids The invention relates to flame resi~tant hydraulic fluids S which are ecologically saf~ and have lubricating propertie~.

Hydraulic ~luid~ based in particular on mineral oils are in common u~e. However, in mining, for safety reason~, flame resistant hydraulic-fluids are neces~ary and these are used in a large number of applications, for example in coal cuttins machines, tunnelling ma~hines, turbo couplings and hydraulic prop~. However, even outside the mining industry, flame resi~tant fluid~ are preferred wherever disa~trou3 fires could be cau~ed by the e~cape of combustible media from the closed hydraulic sy~tem.

The current flame resistant hydraulic fluid~ are in particular aqueous sy3tems, either oil-in-water emul~ions (HFA) or glycol-polyglycoI-wat2r mixtures (~FC). The chief disadvantage of the o/w emul~ions i8 that they are metastable ~y~tems which can become critical in par-ticular owing to temperature variation~ and electrolyte~
(D~-A-3,508,946). Where thickened ~ystem~ are concerned, such a~ are reguir~d to avoid le2kage 108~e8 from the seal~ in pump8 and valve~ and to form lubr~cattng films be~ween solid surface~ in fric~lonal contact, the po1ymers used u3ually have little ~hear stability, if any.
.
HFC fluid~ ba~ed on monoglycol~, oli~oglycol8 or poly~ly-col~ have, in addition to ~ub3tantial flam~ resi~tance, ~0 the advantage of being physiologically harmles~ and ecologically acceptable (P. Lehringer, ~rd~l un~ ~ohle-Erdga~-Petrochemie 41, 230 (198B)3, which i8 particularly advanta~eous in mobile application. where leakage~ of hydraulic fluid often ~eep i~to the 80il- These syst~ms ' . , ~ ''`

', ' , 2~2~
- 2 - o.Z. 4410 are al~o considered to be substantially Rhear-stable, which however can be viewed a~ a critici~m ~ince u~ually particularly those polymers making the greatest contribu-tion to the overall vi8c08ity of the fluid which are most liable to shear damage owing to their chemical stxucture.
A further disadvantage of the current HFC fluids i~ that the pxoportion of active ingredient must be very high 80 that a minimum vi8c06ity i8 retained even a~ Romewhat elevated temperature~. Water content~ < 50% are quite typical h~re (C. Rasp, Tribologie Schmierungstechn. 35, 185 (1988)). Moreover, the additive packages ~or produ-cing good lubricating and anti-wear action~ are ve~y comple~ in these fluids.

The ob~ect i8 therefore to provide flame resistant, ecologically safe hydraulic fluids which have an adequate vi8c08ity and a ~ood lubricating action at low concentra-tion3 of active ingredient.

This ob~ect i3 achieved by aqueous hydraulic fluids which are ba~ed on an aqueous surfactant solution.

The invention accordingly provides aqueou~ hydraulic f luids which are characterized in that they contain 5 30% by wei~ht of alkylpolyglyco~ide, 0 to 20% by w~ight of ~urfactant additive~, 0 - 10% by weight of non-~urfactallt additive~ and water 1;o 100% by weight, the proportion o~ act$ve ingredient being at mo~t 40% by weight .

Surpri~ingly, it ha~ been found that alkylpoly~lyco~ides have, both alone at relatively l~w concentrations and el~e in the presence of other surfactants, a particular-ly high vi8co~ity levQl coupled with a very good lubri-cating action.

Alkylpolyglycoside~

The alkylpolyglycoside~ ussd according to the inv~ntion ~2~
~ 23443-436 3 - ~.Z. 4~10 conform to the general formula (I) R-0-Z~, (I) in which R represents a linear or branched, saturated or un~aturated alkyl radical having 8 to 20, preferably 3 to 18, carbon atom~ and Z~ rapresent~ an o1igoglyco~ide radical with on av~ra~ n = 1 to ~0, preferab1y 1 t~ 5, hexose unit~ or pento~e unit~ or mix~ure~ ~hereof.

ThQ alkyloligo~lyco8id~ u8~d accord~nq to the invent~on can be pr~pared who11y or pa.rtly baRed on renewable raw materL~I 18, by Xno~im proces~ . For ~x~mple d~extrc~83 i~
reac ~d ~n th~ pre~ence of an acidic cataly~t with n-butanol to form butylo11goglyco~ide mixtures which are convertad ~ith long-ohain ~lcoho1s, li~ewise i~ the presence o~ ~n acidlc c~t~ly~t, to form tho desired ~lkyloli~oglyco6ide mixturas. ~e formula of the products can vary within certain lim~ ts . The alkyl radical ~ i~
determined by the choice of long-chain alcohol. It i~
advan~ageou~ on econo~ic ground~ to u~e ~ndu~trially acce~sible surfactant alcohol~ having 8 to 2Q carbon atom~, ~or example oxo ~lcohols, Zieqler alcohols and natural a1cohols fro~ the hydrog~nation of fa~ty acid~
and fatty acid derivativos.

The oligoqlyco~yl radical Z~ i~ detormined on tha on~ hand by the ~eleatlon of the carbohydrate and on the other hand by the re~ulatio~ o~ the average degree of oligo~erization n, ~or example accordin~ to ~-A-1,943,689~ In principle, lt i~ po~ible to ¢onvert known : poly~accharides, ollgo~acc~aride~ and ~ono~acch~rid~ ~or exa~ple ~tarch, maltodextr~n, dextrose, galactoae, mannose, xylo~e and ~o on into alkyloligoglyco3ides.
Parti~ul~r prefere~ce i~ given to the indu~tr~ally ~ccea~ible c~rbohydra~e- ~tnrch, mal~odextrln ~nd dex-troD0. S~nce the industrially relevant alky1polygly-co~ida-~ynthe~es are not reyio-3electlve or ~toreo-selective the alkylpolyglycosldes are always ~ ures ofol~go~era which in turn ar~ m~xtures of different i~ome-ric atructuxe~. Pyrano~e and furano~e ~tructures are ~2~

4 _ o.z. 4410 present side by side, with ~- and ~-~lycosidic linkages.
Even the linkage po~itions differ between pair~ of saccharide radical3.

Depending on the method of synthesis, the alkylpolyglyco-sides may also contain associated substances such as resi~ual alcohol~, monosaccharides, oligosaccharide~ and oligoalkylpolyglycosidesO
Suractant additi~e~

~he 1~me resistant hydraulic fluids according to the invent~on can moreover contain up to 20~ by weight of ~urfactant additives which are selected from the follow-ing compound~ or are composed of mixtures of these compound~:

a3 Alkylbenzene~ulphonate~ordialkylbenzenesulphonate6 of the fonmula (II) ~(R1)C~H3SO3M (II~
in which R denotes a branched or unbranched alXyl radical having 8 to 20 carbon atom~, Rl denotea hydrogen or a branched or unbranched alkyl radical having 1 to lO carbon a~om~, where the total number of carbon atom~ in R and R1 i8 at le~st 8, preferab-ly 10 to 18, and ~ denotes Na, R, ammonium or alkyl-amm~nium.

b) Alkane~ulphonates and/or olefin~ulphonates of the formul~ (III) R''SO3M' (III) in which R'' denotes a saturated or unsaturated, branched or unbranched alkyl radical havinq 8 to 20 carbon atoms and M' denotes Nat R, ammonium or alkylammonium.
c) Pe~roleumaulphonate~

d~ Fatty alcohol derivatives or alkylphenol derivatives of the following foxm~la (IV3:

~22~
, 5 - O.Z. 4410 [R' ' ' (C~H4~lO(R~ ' ' 'O)y3zU~I ~ ' (IV~
in which R' ' ' denotes a saturated, branched or unbranched alkyl .radical having 6 to 20 ~ preferably 8 to 16, carbon atoms, x = O or 1, R'''' denote~ C2H"
or C3H6~ y i5 0 S;O 15, Z iB 1 or 2, U denote~ SO3, CH2COO, CHCOO~ ~v is 0 or 1 and ~' ' denote~ H, ~a, R, a~noni~lm or alkyl a~anoniura.

e) Other ~urfactant additi~re~s are carbo~sylic acid~ with ~elati~ely long, branched ~r ~nbran~::he~, saturat~d or un~aturated hydrocarSon chains and alsc~ par~ial e~ters of pho~phoric acid in particular those of alcohc>ls or of fatty alcohol ethoxylate3 or of allcylphenol ethoxylate~. The latter can be prepared ~y reacting the relevant alcohol~ or oxyethylat~s with phosphoric acids, pho~phoru~ oxides or phosphs~-rus halides.

Finally, cationic ~urfactant~ ~uch as quaternary ammonium compound also have advantaqeou effects as additive~ to alkylpolyglyco~ides in aqueou hydraulic fluid~, for example a pronounced improvement in the lubricating propertie~ .

Non-surfactant additives Suitable non-~urfac:tant additive~ in the hydraulic fluid3 ~ ~ accordLng to the invention are amines or alkanolamine~
used as pH regula~orB or corros~oA inhibitor~; sodium molybdate, ~oric acid aminoe~ters, ben20triazole or toluenetriazole likewi~e a~ corrosion inhibitors;
morpholine or ~-methylmorpholine a~ vapour pha~e inhi-bitor~ cone antifoam~ or other antifoams; glycol and/or glycol ether~ or urea as solubility promoter~ and optionally water ~olubla polymers for ad~u~ting the temperature profile of the vi~co~ity and also pre~ervative~.

Be~ides water a~ the aolvent, the hydraulic fluid accor-- 6 - o.z ?'~
ding to the invention iB based on alkylpolyglycoaides, a toxicologically harmle~ class of surfactan~s having excellent biodegradability (95 to 97~ by weight coupled unit test, DOC). 3 to 30% by weight, preferably 5 to 25%
by weight, of alkylpolyglycoside are present in the fluids according ~-o khe invention and the total concen~
tration of active ingredient~ is at mo3t 40~ by weight, preferably 35~ ~y weight.

~he hydraulic fluid~ according to the invention are u~ually clear in the temperature range between 5 and 80DC, or may be ~lightly opale~cant in the presence of silicon~ antifoams. The fluids are usually rendered weakly alkaline.

The following example~ are intended to describe the fluid3 and trade marks signify the following typ~s of compound:

MARLON^ A i6 the ~odium salt of a linear C10-C~3-alkylbenzene~ulphonic acid (Huls AG) MARLON~PS is the aodium ~alt of a C~3-Cl~-paraffin-sulphonic acid (HU1B AG) Polymekon 730 i~ a silicone antifoa~ (Goldschmldt AG) ~.

A 15% by w~ight ~olution of Cl2-C13-alkylpolyglycoside ~av~ra~e DP 1.7, determined via lH-NMR) i8 prepared 1n deionized watsr. The vi~co~ity behaviour of the solu~ion (rotational vi~co~eter~ Haake RV 20, M 5, 50C, ~hear rate rang2 30-300 ~ec~~) i8 newtonian and the visco~ity i~
about 150 mPa.~. Repeated ultra~ound bombardment (Telsonic USG 1000, 20 kHz) for periods of 10 minutes did not ~lter the vi~co~ity and confirm~ the expected shear ~tability of the 8y8tem. The clarification temperature of the ~olution i0 10C. The solution undergoes no optical change with increasing temperature (up to 80). The wear characteristics (lubricating action) of the solution were ~C~S3~

- 7 - O.Z. 4~10 investigated using the Reichert fric~ional wear balance (weight 108s of the test rolls after a frictional path of 100 m under a load of 1500 g). The average of 3 test runs was 6.6 ~ 0.5 mg at a specific ~urface pre3sure of 2400 N/cm2. No foa~ing was ob~erved during the wear mea~urement. Comparati~e wear tests with deionized water on the one hand and ~cubasol Hydro~h~rm~ 36 ~glycol-based hydraulic fluid) on the other hand gave, under the same conditions, weight losses of 66 and 6.9 mg. Comparison of ~e results demonstrate~ that even a 15% by weight solution of the alkylpolyglycoside ha~ not only an adequate viscosity le~el ~ut also pronounced lubricating properties.
Example 2 A 15% by weight solution of N-C12-C18-N,N,N-trimethyl-ammoni~m chloride in deionized water ha~ a low viscosity (about 1 ~Pa.s) at 50C and its anti-wear effect, deter-mined as in Example 1, is only moderate with a weight 10s8 figure of 34.5 mg. HoweYer, if half of the quaterna~y ammonium compound i8 replaced by Cl2-Cl3-alkyl-polyglycoside (average DP 1.7~, a pronoun~ed lubricati~g action re~ults, with a weight loss of 10.9 ~ 0.6 mg, while he viscosity remains almost uncha~ged and the clarification temperature increases from +2C to +5C.

~xampl0_~

A 10~ by weight solution of C1~-Cl~-alkylpolyglycoside (aver~ge DP about 1.3) in deionized water ha~ newtonian flow behaviour and a viscosity of 70 mPa.~ at 50C. The investigation of the wear behaviour carried out as in ~xample 1 gave a weight lo~ of the test piece of 15 mg.

~xamples 4 to 13 [~ables) The relev~nt examples demonstrate the effectivenes~ of the mixture~ according to the invention wi~h regard to the viscosity level and antiwwear properties. The ultra-- 8 - O.z. ~410 sound bombar~ment carried out with the solutions corresponding to Example 4 and 10 (2 exposures of 10 minute~ with the viscosity being determined after each exposure) demonstrates complete shear stability of the structures producing elevated viscosity. Examples 11 and 12 demonstrate the effectiveness of the mixtures accord-ing to the invention in waters of different hardne~se~
(calcium hardness).

2~2~
_ g _ O.Z. ~410 Table 1 Example No. 4 5 6 7 8 Composition (~ by weight) , _ _ _ _ Cl2cl3-Alkylpoly- - 8.5 10 7 16 glyco~ide (average DP 1.7) CloCl~Alkylpoly- 12.5 - - -glyco~ide (average DP 1.3~
MARLOM A - 8.5 - 7 -MARLON PS- 12.5 - 10 Triisopropylammonium _ 4 _ _ 4 oleate Partial e~ter of pho~- _ _ - 4 -phoric acid wi~h ethoxy-lated nonylphenol having 7 mol of ethylene oxide/mol Polymekon 730 0.15 - - _ _ Isopropanola~ine 3 3 3 3 3 Et~ylane glycol ~ 15 _ _ . .
Vi3c08ity 5~C (c5t) 20 47 4 57 2~
Clarification tempera- _ 3 5 5 3 ture (~C) pH 8.1 8.6 9.7 8.5 ~2 : Frictional wear4.5 3.7 2.6 2.1 59 testl) (mg~
Foam (DIN 53 902) _ _ *2~

1~ Average from 3 test runs with a friction~l path of 100 m and a surface pressure between 3000 and 5000 N/c3n2 2) The ~a~e test in the pre~encQ of 0.15~ by weight of Polymekon 730 gives no foam.

`` 2~2~
- 10 - o.z. 4~10 Table 2 Example No- 9 1~ ll2) 123'13 Composition (~ by weight) , __ _ _ Cl2C,3-AlkYlPlY- _ 8 13 13 25 glycosid~ (a~erage DP 1.7 Clocl4-Alkylp~ly- 7 _ _ _ _ glyco6ide (average DP 1.3 MARLON A 7 8 - _ _ Trii~opropylammvnium _ _ _ _ _ oleate Paxtial e~ter of 4 4 _ _ _ pho phoric acid with eth~xylated nonyl phanol having 7 mol of ethylene oxide/
mol Polymekon~ 730 - - 0.15 0.15 Isopropanolamine 3 3 3 3 3 Ethylene glycol - 15 _ _ _ Vi6co~ity 50~C (cSt) 51 21 32 34 71 Clari~ication tempera- 1 5 - - 6 ture (C) P~ .1 ~.7 8.0 8.1 9 Fxic~ional woar ~8 1.4 2.2 2.3 te~t" (mg) Foam (DIN 53 902~ _ _ _ _ _ Average from 3 te~t run~ with a frictional path of 100 m and a surface pres~ure between 3000 and 5000 N/cm2 2~ Water with 20 degrees of German hardnes~

3) Water with 50 degrees sf German hardne~.

Claims

1. An aqueous hydraulic fluid containing 5 - 30% by weight of alkylpolyglycoside, 0 - 20% by weight of surfactant additives 0 - 10% by weight of non-surfactant additives and water to 100%
by weight, the proportion of active ingredient being at most 40%
by weight.

2. An aqueous hydraulic fluid according to claim 1, wherein the alkylpolyglycoside conforms to the formula R-O-Zn, in which R represents a linear or branched, saturated or unsaturated alkyl radical having 8 to 20 carbon atoms and Zn represents an oligoglycoside radical with, on the average, n = 1 to 10 hexose units or pentose units or mixtures thereof.

3. An aqueous hydraulic fluid according to claim 1 or 2, wherein the surfactant additives are selected from the group containing organic sulphates, organic sulphonates, partial esters of phosphoric acid, oxyethylates, carboxymethylated oxyethylates, salts of carboxylic acids, quaternary ammonium salts, ethylene glycol, glycol ethers, urea and mixtures thereof.