EP1320576A2

EP1320576A2 - Biodegradable functional fluid for mechanic drives

Info

Publication number: EP1320576A2
Application number: EP01985265A
Authority: EP
Inventors: Mathias Woydt; Michael HÖTGER; Jens Kleemann
Original assignee: TEA GmbH
Current assignee: TEA GmbH
Priority date: 2000-09-22
Filing date: 2001-09-20
Publication date: 2003-06-25
Also published as: US7060199B2; US6913707B2; US20050143264A1; US20040094743A1; DE10049175A1; WO2002024841A2; WO2002024841A3

Abstract

The invention relates to a water-based biodegradable functional liquid for mechanical drives, preferably for use in steam engines. The aim of the invention is to create functional liquids for use in mechanical drives, particularly for hydrodynamically lubricating plain bearings, preferably for crankshafts of superheated steam engines having customary non-overly precise bearing play. The inventive liquids should be able to be used in closed power pack systems also in the existence of sump temperatures exceeding 120 DEG C, e.g. in the lubricant pan located under a crank drive and be water-based or able to be diluted with water. According to the invention, this is achieved by a percentually low addition of polyaspartic acid to water or to water-glycol mixtures, whereby polyaspartic acid having a molar mass ranging from 1,000 to 10,000 g/mol is preferably used.

Description

Biodegradable functional fluid for mechanical drives.

The present invention relates to biodegradable functional fluid for mechanical drives according to the preamble of the main and secondary claims.

It is generally known to use glycols and polyglycols for lubrication purposes. Polyglycols have a favorable viscosity-temperature behavior, even with high shear gradients, high shear stability and good lubrication behavior, as well as wear protection and high-pressure properties in mixed and boundary friction conditions. When subjected to thermal stress, they decompose only at temperatures above 260 ° C, depending on the molecular structure and without additives. Resistance to oxidation can be achieved with additives.

The liquid polyethylene glycols with a molar mass of 200-400 g / mol are preferably used, which are water-soluble, rapidly biodegradable, physiologically harmless and skin-friendly.

It is also generally known to produce synthetic lubricants from polyalkylene glycols, a mixture of ethylene and propylene glycols.

From the document DE 196 47 554 A1 it is previously known to produce functional fluids for internal combustion engines on the aforementioned basis, polyalkylene glycols having a number of additives added to them, but which have a very low proportion by weight, <5% by weight, of the fluid. These functional fluids are to be used both as a permanent lubricant and as a permanent coolant. Their special properties are good heat transfer, biodegradability, no heavy metals and smoke-free and soot-free combustion if they are carried over into combustion chambers.

It is previously known from US Pat. No. 5,401,428 that water-miscible cooling lubricants for machining processes contain 5-50% by weight sodium salt of polyaspartic acid - PAS - and are used in open tribological systems. As the proportion of polyaspartic acid increases, the coefficient of friction is reduced. It is also known from document EP 0 596 197 to preferably add esters of aspartic acid as an additive for corrosion protection to mineral hydraulic oils.

US 4,855,070 shear-stable water-glycol are previously known

Hydraulic fluids with 30 to 40% by weight water, 35 to 50% by weight

Diethylene glycol, with 0.8% - 5% aliphatic carboxylic acids and 1% - 4%

Alkylmorpholine are included.

As a multifunctional additive, this morpholine component secures the high pressure and

Wear protection and corrosion protection properties. In addition, triazoles and thiazoles can be included as anti-corrosion agents.

According to OECD 301 B, these liquids are 85% biodegradable, however all additives according to VwVwS-99 are in the water hazard classes, in the following

WGK called, WGK 2 or WGK 3 classified.

All additives used in the functional fluids described above do not meet the future relevant toxicological and ecological criteria, which e.g. B. in the draft of ISO CD15380, ASTM D6046-96 or for the German environmental label UZ79 for hydraulic oils are required.

It is previously known from EP 0464491 to use ester-based tocopherols as lubricants for machines in the food industry.

The invention has for its object to provide biodegradable and non-toxic functional fluids for mechanical drives, which are particularly suitable for the hydrodynamic lubrication of slide bearings, preferably for crankshafts of superheated steam engines, with the usual, not over-precise bearing play. These functional fluids are to be used in closed engine systems even at sump temperatures of higher than 120 ° C, e.g. B. in the lubricant pan under a crank mechanism, be applicable and be based on water or be dilutable with water.

According to the invention, this task is achieved by the compositions described in the characterizing part of the main and the secondary claims. In a first embodiment, water-based functional fluids according to the invention consist of water and an addition of polyaspartic acid.

The polyaspartic acid contained in all of the above-mentioned functional liquids according to the invention preferably has a molar mass greater than 1,000 g / mol, preferably up to 3,400 g / mol or up to 10,000 g / mol. You can preferably both in the form of

Na-PAS - sodium salt of polyaspartic acid - as well

NH ₃ -PAS - ammonium salt of polyaspartic acid with a proportion of <5 wt .-% of the functional fluid are used.

In a second variation, the functional liquid consists of water and polyethylene and / or alkylene glycols with a molar mass of greater than 1200 g / mol or from proportions of both of the aforementioned substances with the addition of the salts of polyaspartic acid mentioned.

In a third variation, functional fluids consist of 1.2 monopropylene glycol, also called 1.2 propanediol - and an addition of polyaspartic acid.

In the fourth variation, functional fluids consist of 1.2 monopropylene glycol and polyethylene or polyalkylene glycols as well as an addition of polyaspartic acid.

In the fifth variation, functional fluids consist of triethylene glycol and an addition of polyaspartic acid.

In the sixth variation, the functional liquids can be diluted with water and are biodegradable, the basic liquid consisting of polyethylene or polyalkylene glycols with a molar mass of less than 1,000 g / mol or mixtures of these substances and containing polyaspartic acid.

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These functional fluids according to the 2nd to 6th variant have very good high-pressure properties and in some cases exceed the functional fluids intended in the future for engine lubricating oils or for the lubrication and cooling of internal combustion engines. In the seventh variation, the functional liquids can be diluted with water and are partially biodegradable, the basic liquid consisting of tocopherol - vitamin E - with the addition of a proportion of polyaspartic acid with a molar mass of greater than 1,000 to 10,000 g / mol. Functional fluids composed in this way are suitable for application temperatures of less than 100.degree. Tocopherols are natural and human identical substances.

Properties and effects of applied substances polyaspartic acids

Functional fluids according to the invention contain salts of polyaspartic acid, the proportion of which is advantageously <5% by weight. All types of D-, L- and DL-polyaspartic acids are suitable, but preferably L-polyaspartic acid, as a salt of potassium, sodium, lithium or ammonium with a molecular weight between 1,000 and 10,000 g / mol.

Their use generally causes an increase in the viscosity and the viscosity index of water or of water components introduced into a base liquid made of polyethylene or polyalkylene glycols. In the absence of polyaspartic acid, there would be a significant reduction in viscosity as a result of the inevitable introduction of water, which entails an operational dilution.

Multifunctional properties of polyaspartic acid result from the fact that it is polar by the - [COOH] - and [C = O] - groups and these groups of surfaces are absorbed in tribological systems. These molecules form wear protection and result in high pressure properties (AW- / EP), which lead to a reduction in mixed / limit friction under start / stop conditions.

The molecules are strongly anionic and act as a strong regulator or stabilizer with a TBN number of »100 mgKOH / g for the pH value.

The polyaspartic acid acts as a dispersing agent, as a corrosion protection additive and prevents limescale deposits. It can be used up to an ambient temperature of 120 ° C. Polyaspartic acid is a nature-identical substance and is classified as slightly water-endangering "WGK 1" and, in principle, is biodegradable or biodegradable.

polyethylene glycols

The polyethylene glycols which can be used according to the invention [CAS: 8038-37- 7; CAS: 9002-90-8; CAS: 25322-58-3] have a molar mass greater than 200 g / mol and preferably up to 3,500 g / mol. The solubility of wax-like polyethylene glycol with a molar mass of 3,500 g / mol is, for example, 56% in water at 20 ° C. In an inert atmosphere, polyethylene glycols decompose without residues above 250 ° C. This is very important for use in a steam engine, because the spread of polyethylene glycols into the steam cycle can hardly be ruled out, but remains without consequences.

Because of their water solubility, polyethylene glycols are classified as slightly water-endangering "WGK 1" and can only be classified as toxicological in large quantities. The biodegradability (OECD 301 B) is> 85% for molar masses less than 10,000 g / mol.

triethylene

This glycol form [CAS: 112-27-6] can also be used according to the invention. Because of the water solubility, its low toxicity and the slow biodegradation - 14d> 95% - it is classified as slightly water-endangering "WGK 1" and can be safely used.

polyalkylene

The butanol-initiated polyalkylene glycols, also known as diols, are polymeric

Mixtures of ethylene glycol and propylene glycol, in any proportion in the

Ratio of 1: 9 to 9: 1 are suitable and applicable.

Because of their water solubility they are weakly hazardous to water

"WGK 1" classified. The toxicity of the PAGs is lower than that of glycerol. THIS PAGE WAS NOT FURNISHED UPON FILING THE INTERNATIONAL APPLICATION

- that the basic liquids and additives do not have an "R" phrase according to EU Directive 67/548 / EEC and

- The oral mammalian toxicity (LD ₅₀ rat) is greater than 2,000 mg / kg.

It is also particularly suitable for superheated steam engines, since a lubricant for their crankshafts must be able to absorb up to 50% water as a result of inevitable "blow-by quantities" in the cylinder units. Under such conditions, non-water-miscible base oils and lubricants cannot be used Find.

Furthermore, the viscosity and lubricating properties of the functional fluids according to the invention in engine construction, common material pairings and constructions, e.g. B. AISn20 for plain bearing treads and tempering steels for the crankshaft.

They are sufficient for a temperature range of - 30 to + 150 ° C, which must be taken into account when operating steam engines.

At high steam temperatures, which can be permanently up to 600 ° C. in the steam cycle and even higher in the work space, all components of the functional fluids according to the invention only disintegrate into gaseous and / or water-soluble reaction products. This is crucial because the lubricating medium inevitably takes place via the cylinder track and the working space in the steam circuit in conventional piston machines.

The aforementioned temperatures are above the flash points (flash point according to ASTM D-92) from 200 to 250 ° C. of conventional lubricants based on hydrocarbons, e.g. B. mineral or polyalphaolefin oils, which would pose a fire hazard in the event of a leak.

As a water-based functional liquid, the composition according to the invention ensures frost protection down to -30 ° C.

At an application temperature of less than 100 ° C, tocopherols (vitamin E) are suitable as a basis for the biodegradable functional fluids according to the invention for mechanical drives with the addition of a proportion of polyaspartic acid with a molar mass of greater than 1,000 to 10,000 g / mol. Tocopherols' ^*

[CAS: α = 59-02-9; CAS: β = 148-03-8; CAS: γ = 7616-22-0; CAS: δ = 119-13-1] are natural and human-identical substances, whereby ß- γ- and δ-tocopherols are more temperature-stable than α-tocopherol. All forms act as antihydrolysis, antioxidant and dispersant and have a certain regeneration ability. Tocopherols are classified in WGK 1 and approved by the US FDA for drug preparations, although they are only 4% to 40% biodegradable.

Functional fluids according to the invention can also be used in underground mining, for engine lubrication and in the food and pharmaceutical industries.

Table 1 High-pressure properties according to DIN 51350-2 of functional fluids according to the invention

Table 2 High pressure properties according to DIN 51350-2 of motor oils or functional fluids according to DE 19647554 A1.

Claims

claims

1. Biodegradable functional fluid for mechanical drives based on water, preferably for use in steam engines, characterized in that it has an addition of polyaspartic acid. ,

2. Biodegradable functional fluid according to claim 1, characterized in that it contains over 50% by weight of polyethylene glycol.

3. Biodegradable functional fluid according to claim 1 and 2, characterized in that it has a proportion of polyethylene glycol with a molar mass greater than greater than 200 g / mol.

4. Biodegradable functional fluid for mechanical drives, preferably for use in steam engines, characterized in that the base fluid consists of 1.2 monopropylene glycol and has an addition of polyaspartic acid.

5. Biodegradable functional fluid for mechanical drives, preferably for use in steam engines, characterized in that the base fluid consists of polyethylene or polyalkylene glycols with a molar mass less than 3,000 g / mol and mixtures of these components and has an addition of polyaspartic acid.

6. Biodegradable functional fluid according to the preceding claims, characterized in that it contains a proportion of polyaspartic acid with a molar mass of greater than 1,000 to 10,000 g / mol.

7. Biodegradable functional fluid for mechanical drives, preferably for use in steam engines, characterized in that it consists of vitamin E - tocopherol - and a proportion of polyaspartic acid with a molar mass of greater than 1,000 to 10,000 g / mol.

8. Biodegradable functional fluid according to the preceding claims, characterized in that the proportion of polyaspartic acid is preferably formed by sodium or ammonium salt of the polyaspartic acid with a molar mass of 3,400 - 3,700 g / mol.

9. Biodegradable functional fluid according to the preceding claims, characterized in that polyaspartic acid is contained with 1 to 5 wt .-%.