EP0587594B1 - Use of 2-ethylhexyl esters of fatty acids as cold-cleaning agents - Google Patents

Abstract

PCT No. PCT/EP92/01044 Sec. 371 Date Nov. 19, 1993 Sec. 102(e) Date Nov. 19, 1993 PCT Filed May 13, 1992.2-Ethylhexyl esters of fatty acids, optionally mixed with emulsifiers, solubilizers, corrosion inhibitors, and/or water, are useful as low viscosity agents for the cold cleaning of metal surfaces contaminated mainly with oil. Such agents are non-toxic when inhaled and completely biodegradable.

Description

The invention relates to the use of fatty acid 2-ethylhexyl esters as cold cleaning agents for predominantly oil-contaminated metal surfaces and agents which contain these esters.

Cold cleaning is a widely used method for the preparation and care of materials or finished products. In general, it involves the removal of fats, oils, tar, bitumen, lubricants, waxes and similar hydrophobic materials from hard surfaces, in particular metal surfaces. However, other materials such as sand, dust, corrosion products or residues of various solvents can also be contained in these substances to be removed. The cold cleaning is generally carried out in the temperature range from 10 to 40 ° C., the workpieces to be cleaned being washed with the cold cleaner, immersed in the agent or sprinkled with the agent, sprayed or otherwise brought into contact.

Halogenated hydrocarbons such as, for example, 1,1,1-trichloroethane or methylene chloride are suitable as agents for cold cleaning. However, substances of this type are questionable from an occupational medical point of view and for ecological reasons and therefore require Extensive occupational safety and recovery measures to protect people and the environment.

Instead of the halogenated hydrocarbons, gasoline distillates are therefore preferably used for cold cleaning, which are less harmful from an ecotoxicological point of view, but have a comparatively low cleaning performance. In German patent application DE 35 37 619 A1 it is therefore proposed to use 0.2 to 6% by weight solutions of fatty acid alkyl esters with a total number of 12 to 40 carbon atoms in gasoline distillates as agents for cold cleaning. Although the cleaning performance of such agents is quite satisfactory, there are still serious concerns from an occupational medical and ecological point of view, since the use of gasoline distillates in the agents on the one hand poses a potential inhalation hazard and, on the other hand, contributes to a serious COD pollution of the wastewater due to poor biodegradability.

The object of the invention was therefore to develop new means for cold cleaning metal surfaces which are free from the disadvantages described.

The invention relates to the use of fatty acid 2-ethylhexyl esters, optionally in a mixture with emulsifiers, solubilizers, corrosion inhibitors and / or water, as a cold cleaning agent for predominantly oil-contaminated metal surfaces.

Although the suitability of fatty acid alkyl esters for cold cleaning is known in principle, it has surprisingly been found that that a particularly advantageous cleaning performance can be achieved with fatty acid 2-ethylhexyl esters, optionally in combination with emulsifiers, solubilizers and corrosion inhibitors and / or water. The advantage of the invention can be seen in particular in the fact that the use of gasoline distillates is unnecessary. Fatty acid 2-ethylhexyl ester and the agents containing it are non-inhalation-toxic, completely biodegradable and low-viscosity. Since fatty acid 2-ethylhexyl esters have a particularly high affinity for metal surfaces, they are not completely degreased, rather a fine ester film is formed, which offers additional, desired corrosion protection.

Fatty acid 2-ethylhexyl esters are known substances which can be obtained by the relevant methods of preparative organic chemistry, for example by esterification of fatty acids with 2-ethylhexanol in the presence of p-toluenesulfonic acid or tin grinding.

According to the invention, 2-ethylhexyl esters of fatty acids with 6 to 22 carbon atoms and 0 or 1 double bond can be used. Typical examples are the 2-ethylhexyl esters of caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, elaidic acid, petroselinic acid, arachic acid, gadoleic acid, behenic acid or erucic acid. As is customary in fat chemistry, esters of technical fatty acid fractions are also suitable, such as those obtained in the pressure splitting of natural fats and oils, for example coconut oil, palm oil, palm kernel oil, turnip oil, sunflower oil or beef tallow. Preferred are 2-ethylhexyl esters of fatty acids with 8 to 14 carbon atoms, especially based on C₁₂₋₁₋ coconut fatty acid.

• a) Fettsäure-2-ethylhexylester
  sowie gegebenenfalls
  • b1) Emulgatoren,
  • b2) Lösungsvermittler,
  • b3) Korrosionsinhibitoren und/oder
  • b4) Wasser.

Another object of the invention relates to agents for cold cleaning containing predominantly oil-contaminated metal surfaces

• a) 2-ethylhexyl fatty acid
  and if necessary
  • b1) emulsifiers,
  • b2) solubilizer,
  • b3) corrosion inhibitors and / or
  • b4) water.

Agents with a particularly high cleaning performance are distinguished by the fact that they contain 2-ethylhexyl esters of fatty acids having 6 to 22, in particular 8 to 14, carbon atoms and 0 or 1 double bond.

The fatty acid 2-ethylhexyl esters (component a) can be used alone or in combination with one or more of the ingredients mentioned (components b1-b4). It is possible, for example, to market the 2-ethylhexyl ester in 100% by weight form or in the form of a concentrate with an ester content of at least 15% by weight and, at the site of cleaning with water, to an application concentration of, for example, 1 up to 10 wt .-% - based on the agent - to dilute. However, agents are preferred which, in addition to the 2-ethylhexyl esters, also contain at least one emulsifier, solubilizer and / or corrosion inhibitor.

In the following, emulsifiers are to be understood as addition products of an average of 1 to 10 moles of ethylene and / or propylene oxide onto fatty alcohols with 6 to 22 carbon atoms and 0 or 1 double bond.

These are nonionic surfactants which are obtained by the known and well-established process of base-catalyzed alkoxylation of compounds with acidic hydrogen atoms. Preference is given to using adducts of on average 1 to 10, preferably 2 to 5, moles of ethylene oxide with fatty alcohols having 8 to 18, preferably 8 to 14, carbon atoms, and addition products with, on average, 2 to 10 moles of ethylene oxide and 1 to 5 moles of propylene oxide with fatty alcohols having 12 up to 18 carbon atoms. The emulsifiers can be present in the agents according to the invention in amounts of 1 to 25, preferably 3 to 10% by weight, based on the agents.

Suitable solubilizers are substances which are selected from the group formed by Guerbet alcohols with 16 to 20 carbon atoms, butyl diglycol and reaction products of on average 1 to 10 mol of ethylene oxide with fatty acid glyceride esters with 6 to 22 carbon atoms and 0 or 1 double bond in the fatty acid residue.

Guerbet alcohols are branched primary alcohols which are obtained, for example, by self-condensation of linear primary alcohols having, for example, 8 to 10 carbon atoms in the presence of alkali catalysts [Soap, Cosm.Chem.Spec., 52 (1987)] .

The reaction products of ethylene oxide with fatty acid glyceride esters are also known. In the production of these substances, ethylene oxide units are inserted into the ester linkage of natural or synthetic mono-, di- or triglycerides or attached to existing free hydroxyl groups. Typical examples are reaction products of 1 to 10, preferably 2 to 5 moles of ethylene oxide with coconut oil, palm oil, palm kernel oil, turnip oil, sunflower oil, beef tallow, lauric acid monoglyceride, C₁₂₋₁₄ coconut fatty acid monoglyceride, stearic acid monoglyceride or oleic acid monoglyceride. The solubilizers can be present in the agents according to the invention in amounts of 1 to 25, preferably 3 to 10% by weight, based on the agents.

Corrosion inhibitors are to be understood as meaning fatty acid alkanolamides with 12 to 22 carbon atoms and 0 or 1 double bond in the solid acid residue and 2 to 4 carbon atoms in the alkanol residue. Typical examples are lauric acid ethanolamide, stearic acid dipropanolamide, C₁₂₋₁₄ coconut fatty acid triethanolamide and especially oleic acid ethanolamide. The corrosion inhibitors, which also have a co-emulsifying effect, can be present in the agents according to the invention in amounts of 1 to 10, preferably 2 to 5% by weight, based on the agents.

The agents can be brought to the market anhydrous and can only be diluted on site to an application concentration of, for example, 1 to 10% by weight, based on the agent. However, it is also possible to produce water-containing concentrates or aqueous solutions which have already been diluted to the application concentration.

The agents according to the invention are suitable, for example, for washing engines or engine parts. You can also use it for cleaning of metallic surfaces before priming, painting or coating. Reliable removal of preservatives for the purpose of transportation, for example preservation wax on the surface of brand new automobiles, can also be carried out with the cold cleaners according to the invention. Further areas of application for the agents according to the invention are the cold cleaning of various surfaces, for example of glasses, ceramic materials, such as tiles, various lacquered, enamelled or coated surfaces, and of surfaces of chemical materials.

In combination with conventional anionic, nonionic or amphoteric surfactants, such as, for example, alkyl sulfates, alkyl ether sulfates, alkylbenzenesulfonates, olefin sulfonates, alpha-sulfofatty acid esters, alkane sulfonates, isethionates, taurides, sarcosides, ether carboxylic acids, alkyl glucosides, alkyl amido betaines, and imidazolinas, as are suitable for the preparation of imidazolinas, as well as imidazolinashenasene asenazium.

The following examples are intended to explain the subject matter of the invention in more detail without restricting it.

Examples

The cleaning effect of the agents according to the invention was checked in a dipping test on iron test panels which had previously been treated with standard dirt.

• a) Production of standard dirt
  acc. Federal Office of Defense Technology and Procurement TL 6850-017:
  100 g of a mixture containing 30 g iron (III) oxide, 20 g motor oil 20 W / 50, 20 g gear oil SE90, 10 g carbon black, 10 g sea sand, 9 g lubricating grease (plain bearing grease MO) and 1 g bentonite were mixed in 50 ml carbon tetrachloride dispersed.
• b) Impact test
  Iron test plates (0.2 x 2.5 x 5 cm) were immersed in the standard dirt, air dried at 20 ° C for at least 1 h and then weighed. The soiled iron plates were then immersed at 50 ° C. for 5 minutes in 50 ml each of the formulations A, B, C and D (composition see Table 1). The dripping-wet test plates were then sprayed with 100 ml of tap water, dried in air for 5 min and in a drying cabinet at 110 ° C. for 20 min. After a final drying in air over a period of 30 minutes, the test panels were reweighed.

The ratio of the removed dirt to the originally applied dirt was specified as a% cleaning effect (% -R) (see Tab. 2).

Tab. 1: Composition of the sample recipes in% by weight Recipe A B C. D EHK 24th 17th 94 94 G20 5 7 - - D04 4th - - - LS6 10th 5 - - LS45 - - 5 2nd LS54 - - - 3rd RHE - 7 - - BDG 3rd - - - C0D 6 4th 1 1 H₂0 46 60 - - Tab. 2: Cleaning performance of the sample recipes Recipe Cleaning performance% -R A 95.4 B 93.2 C. 95.6 D 96.8

List of substances used:

EHK:

C₁₂₋₁₄ 2-ethylhexyl coconut fatty acid;

G20:

C₂₀ Guerbet alcohol;

D04:

Addition product of an average of 4 moles of ethylene oxide with octanol;

LS6:

Addition product of an average of 6 moles of ethylene oxide with a C _12/14 coconut fatty alcohol;

LS45:

Addition product of an average of 4 moles of propylene oxide and 5 moles of ethylene oxide with a C _12/14 coconut fatty alcohol;

LS54:

Addition product of an average of 5 moles of propylene oxide and 4 moles of ethylene oxide with a C _12/14 coconut fatty alcohol;

RHE:

Addition product of an average of 5 moles of ethylene oxide onto a C _12/14 coconut fatty acid triglyceride;

BDG:

Butyl diglycol;

COD:

Oleic acid diethanolamide.

Claims (8)

1. The use of fatty acid-2-ethylhexyl esters, optionally in admixture with emulsifiers, solubilizers, corrosion inhibitors and/or water as cold cleaning preparations for predominantly oil-contaminated engines and engine parts.
2. The use claimed in claim 1, characterized in that 2-ethylhexyl esters of fatty acids containing 6 to 22 carbon atoms and 0 or 1 double bond are used.
3. Cold cleaning preparations for predominantly oil-contaminated metal surfaces containing

   a) 2-ethylhexyl esters of fatty acids containing 6 to 22 carbon atoms and 0 or 1 double bond,

   b1) emulsifiers,

   b2) solubilizers selected from the group consisting of C₁₆₋₂₀ Guerbet alcohols, butyl diglycol and reaction products of on average 1 to 10 moles of ethylene oxide with fatty acid glyceride esters containing 6 to 22 carbon atoms and 0 or 1 double bond in the fatty acid component,

   b3) corrosion inhibitors and/or

   b4) water.
4. Preparations as claimed in claim 3, characterized in that they contain emulsifiers selected from the group of adducts of on average 1 to 10 moles of ethylene and/or propylene oxide with fatty alcohols containing 6 to 22 carbon atoms and 0 or 1 double bond.
5. Preparations as claimed in claim 3, characterized in that they contain corrosion inhibitors selected from the group of fatty acid alkanolamides containing 12 to 22 carbon atoms and 0 or 1 double bond in the fatty acid component and 2 to 4 carbon atoms in the alkanol component.
6. Preparations as claimed in claims 3 to 5, characterized in that they contain the fatty acid-2-ethylhexyl esters in quantities of 15 to 100% by weight, based on the preparation.
7. Preparations as claimed in claims 3 to 6, characterized in that they contain the emulsifiers in quantities of 1 to 25% by weight, based on the preparation.
8. Preparations as claimed in claims 3 to 7, characterized in that they contain the solubilizers in quantities of 1 to 25% by weight, based on the preparation.