DE3926397A1 - HYDRAULIC LIQUIDS - Google Patents

Description

The invention relates to flame-retardant hydraulic fluids, that are environmentally friendly and have lubricating properties.

Hydraulic fluids based on mineral oil are particularly common Base. In mining, however, are difficult for safety reasons flammable hydraulic fluids needed, the diverse applications there dung z. B. in Schrämm machines, track jacking machines, turbo Find clutches and hydraulic rams. But also outside of the mountain flame retardant liquids are preferred everywhere there, where there is flammable media escaping from the closed hydraulics devastating fires.

The current flame retardant hydraulic fluids are especially aqueous systems, either oil-in-water emulsions (HFA) or glycol-polyglycol-water mixtures (HFC). The main disadvantage of o / w emulsions is that they are metastable systems, which is particularly due to temperature fluctuations and electrolytes can become critical (DE-OS 35 08 946). Is it thickened Systems such as avoiding leakage in the gap Pumps and valves or the construction of lubricating Require films between rubbing solid surfaces the polymers used here usually do not or only to a limited extent sufficiently shear stable.

Have HFC fluids based on mono-, oligo- or polyglycols in addition to extensive flame resistance, the advantage of physiological Harmlessness and ecological acceptance (P. Lehringer, petroleum and Coal-natural gas petrochemicals 41, 230 (1988)), which is particularly advantageous in mobile use is where hydraulic fluid leaks are often in the Soil seep away. The systems are also considered largely shear stable, which is to be seen critically in view of the fact that ge usually the polymers in particular make the highest contribution to the overall vis fluidity due to its chemical nature Structure are most at risk of shear. Another disadvantage of current HFC liquids is that the proportion of active Substance must be very high, even at a slightly elevated temperature  still have a minimum viscosity. Water content is 50% quite typical here (C. Rasp, Tribologie Schmierungstechn. 35, 185 (1988). In addition, the additive packages are cheaper to produce Effects of lubrication and wear protection here very much complex.

It was therefore the task of flame retardant, environmentally friendly Develop hydraulic fluids that at low active ingredient con are sufficiently viscous and have a favorable lubricating effect.

The task was solved by aqueous hydraulic fluids, which contain an aqueous surfactant solution as the basis.

The invention therefore relates to aqueous hydraulic fluids, which are characterized in that they contain 5-30% by weight of alkyl poly glycoside, 0 to 20 wt% surfactant additives, 0-10 wt% non- contain surfactant additives and water ad 100 wt .-%, the Active ingredient content is a maximum of 40 wt .-%.

It has surprisingly been found that alkyl polyglycosides already lower concentrations alone or in the presence of others Surfactants have a particularly high viscosity level at the same time very good lubricating effect.

Alkyl polyglycosides

The alkyl polyglycosides used according to the invention correspond to the general formula (I)

RON _n (I)

in the R for a linear or branched, saturated or unsaturated alkyl radical having 8 to 20, preferably 9 to 18, carbon atoms and Z _n for an oligoglycoside radical with an average of n = 1 to 10, preferably 1 to 5, hexose or pentos units or mixtures thereof.

The alkyl oligoglycosides used according to the invention can be: known methods entirely or partially based on renewable Raw materials are manufactured. For example, dextrose is used in Presence of an acid catalyst with n-butanol to give butyl oligoglyco sid mixes implemented, which also with long-chain alcohols in the presence of an acid catalyst to the desired alkyloli glycoside mixtures are re-glycosidated. The formula of the products is can be varied within certain limits. The alkyl radical R 'is by the Long-chain alcohol selection set. Favorably from economy reasons are the industrially accessible surfactant alcohols 8 to 20 carbon atoms, e.g. B. oxo alcohols, Ziegleralkohole and native Alcohols from the hydrogenation of fatty acids or fatty acid derivatives.

The oligoglycosyl radical Z is selected on the one hand by the selection of the Carbohydrate and on the other hand by adjusting the middle Degree of oligomerization n z. B. according to DE-OS 19 43 689. in the As is known, polysaccharides, oligosaccharides and Monosaccharides e.g. B. starch, maltodextrins, dextrose, galactose, Mannose, xylose, etc. can be converted to alkyl oligoglycosides. The carbohydrates available on an industrial scale are particularly preferred Starch, maltodextrins and dextrose. Because the economical interesting alkyl polyglycoside syntheses not regio- and If the course is stereoselective, the alkyl polyglycosides are always mixtures of oligomers, which in turn are mixtures of different isomeric forms represent. They are side by side with α- and β-glycosidic Bonds in pyranose and furanose form. Even the linking places between two saccharide residues are different.

Due to the synthesis, the alkyl polyglycosides can also be accompanying substances such as residual alcohols, monosaccharides, oligosaccharides and oligoalkyl poly contain glycosides.

Surfactant additives

The flame-retardant hydraulic fluids according to the invention can also contain up to 20 wt .-% surfactant additives are selected from the following compounds or from Mixtures of these compounds consist of:

• a) Alkylbenzene or dialkylbenzenesulfonates of the formula (II) R (R₁) C₆H₃SO₃M (II) in which R is a branched or unbranched alkyl radical having 8 to 20 C atoms, R ₁ H or a branched or unbranched alkyl radical having 1 to 10 C. -Atoms, where the sum of carbon atoms of R and R _{1 is} at least 8, preferably 10 to 18, and M is Na, K, ammonium or alkylammonium.
• b) alkane sulfonates and / or olefin sulfonates of the formula (III) R''SO₃M '(III), in which R' 'is a saturated or unsaturated, branched or unbranched alkyl radical with 8 to 20 carbon atoms and M ′ Na, K, ammonium or mean alkylammonium.
• c) Petroleum sulfonates
• d) Fatty alcohol or alkylphenol derivatives of the following formula (IV) [R ′ ′ ′ (C₆H₄) _x O (R ′ ′ ′ ′ O) _y ] _z U _v M ′ ′ (IV) in which R ′ ′ ′ is a saturated one , branched or unbranched alkyl radical having 6 to 20, preferably 8 to 16 carbon atoms, x = 0 or 1, R ′ ′ ′ ′ C ₂ H ₄ or C ₃ H ₆ , y 0 to 15, z 1 or 2, U SO ₃ , CH ₂ COO, CHCOO, v 0 or 1 and M ′ ′ represent H, Na, K, ammonium or alkyl ammonium.
• e) Other surfactant additives are carboxylic acids with longer, branched or unbranched, saturated or unsaturated Hydrocarbon chains and phosphoric acid partial esters in particular those of alcohols or of fatty alcohol or alkylphenoloxy laten. The latter can be implemented by implementing the relevant Alcohols or oxethylates with phosphoric acids, phosphorus oxides or Produce phosphorus halides.

Finally, cationic surfactants such as quaternary ammonium also show compounds as additives to alkyl polyglycosides in aqueous Hydraulic fluids beneficial effects such. B. a strong one Improve the lubricating properties.

Non-surfactant additives

Suitable non-surfactant additives in the hydrau according to the invention Liquids are amines or alkanolamines as pH regulators or Corrosion inhibitors; Sodium molybdate, boric acid amine ester, benzotri alzol or toluene triazole also as corrosion inhibitors; Morpho lin or N-methylmolpholin as vapor phase inhibitors; Silicone ent foamers or other defoamers; Glycol and / or glycol ether or Urea as a solubilizer and optionally water-soluble Liche polymers to correct the temperature profile of the viscosity as well as preservatives.

In addition to water as the solvent, the hydraulic fluid according to the invention is based on the alkyl polyglycosides, a toxicologically, harmless surfactant class of excellent biodegradability (95 to 97% by weight coupled unit test, DOC). 3 to 30 wt .-%, preferably 5 to 25 wt .-%, alkyl polyglycoside are contained in the liquids according to the invention, the total active ingredient concentration at max. 40% by weight, preferably 35% by weight.

The pressure fluids according to the invention are usually in tempera range between 5 and 80 ° C clear or possibly in the presence of Silicon defoamers slightly opalescent. You are ordinary weakly alkaline.

The following examples are intended to illustrate the liquids, where
MARLON® A linear C ₁₀ C ₁₃ alkylbenzenesulfonate Na salt (Hüls AG)
MARLON® PS C ₁₃ C ₁₇ paraffin sulfonate sodium salt (Hüls AG)
Polymekon® 730 silicone defoamer (Goldschmidt AG)
mean.

Example 1

A 15% by weight solution of C ₁₂ C ₁₃ -alkyl polyglycoside (DP 1.7, determined via ¹ H-NMR) in demineralized water was prepared. The viscosity behavior of the solution (rotation viscometer Haake RV 20, M 5, 50 ° C, shear range 30-300 sec ^-1 ) is Newtonian and is approx. 150 mPa × s. Multiple ultrasound (Telsonic USG 1000, 20 kHz), each lasting 10 minutes, did not change the viscosity and confirmed the assumed shear stability of the system. The clear point of the solution is 10 ° C. As the temperature rises (up to 80 °), the solution does not undergo any optical change. The wear behavior (lubrication effect) of the solution was examined with the friction wear balance according to Reichert (weight loss of the test rollers after 100 m friction distance and 1500 g load). The mean value from 3 test runs was 6.6 ± 0.5 mg at a specific surface pressure of 2400 N / cm ² . No foam development was observed during wear measurement. Comparative wear tests with demineralized water on the one hand and Ecubasol Hydrotherm® 36 (hydraulic fluid based on glycol) on the other hand showed weight loss values of 66 and 6.9 mg under similar conditions. The comparison of the results demonstrates that even a 15% by weight solution of the alkyl polyglycoside has not only a sufficient viscosity level but also strong lubricating properties.

Example 2

A 15% by weight solution of NC ₁₂ -C ₁₈ -N, N, N trimethylammonium chloride in demineralized water is low viscosity (approx. 1 mPa × s) at 50 ° C, its wear-preventing effect - carried out analogously to Example 1 - is only mediocre with 34.5 mg weight loss. However, if half of the quaternary ammonium compound is replaced by C ₁₂ C ₁₃ alkyl polyglycoside (DP 1.7), a strong lubricating effect results with a weight loss of 10.9 ± 0.6 mg, whereas the approximate viscosity remains unchanged and the clear point of + 2 ° C to + 5 ° C increases.

Example 3

A 10% by weight solution of C ₁₀ -C ₁₄ -alkyl polyglycoside (DP approx. 1.3) in demineralized water shows Newtonian flow behavior and has a viscosity of 70 mP × s at 50 ° C. The analysis of the wear behavior carried out analogously to Example 1 showed a weight loss of the test specimen of 15 mg.

Examples 4 to 13 (tables)

The relevant examples demonstrate the effectiveness of the mixtures according to the invention with regard to viscosity level and Wear protection. The solutions according to Examples 4 and 10 performed sonication (2 times 10 minutes each with subsequent viscosity measurement) shows a complete shear stability of the the increased viscosity generating structures. With examples 11 and 12 the effectiveness of the mixtures according to the invention in Water different hardness (calcium hardness) demonstrated.  

Table 1

Table 2

Claims (3)

1. Aqueous hydraulic fluids, characterized in that they
5-30% by weight alkyl polyglycoside
0-20% by weight of surfactant additives
0-10% by weight of non-surfactant additives and
Water ad 100% by weight
included, the active ingredient content being a maximum of 40% by weight. 2. Aqueous hydraulic fluids according to claim 1, characterized in that the alkyl polyglycoside corresponds to the formula RON _n , in which R for a linear or branched, saturated or unsaturated alkyl radical having 8 to 20 carbon atoms and Z for an oligoglycoside radical with an average of n = 1 to 10 hexose or pentose units or mixtures thereof. 3. Aqueous hydraulic fluids according to claims 1 and 2, characterized, that as surfactant additives organic sulfates, organic Sulfonates, phosphoric acid partial esters, oxethylates, carboxymethy lated oxyethylates, carboxylic acid salts, quaternary ammonium salts, Ethylene glycol, glycol ether and / or urea can be used.