EP0505484A1

EP0505484A1 - Non-volatile solvent for aroma-containing active ingredients

Info

Publication number: EP0505484A1
Application number: EP91902175A
Authority: EP
Inventors: Karl Dr. Schmid; Josef Dr. Steber; Reinhold Wüst; Peter Dr. Gode
Original assignee: Henkel AG and Co KGaA
Current assignee: Henkel AG and Co KGaA
Priority date: 1989-12-09
Filing date: 1990-12-03
Publication date: 1992-09-30
Also published as: WO1991009096A3; WO1991009096A2; CA2098109A1; DE3940803A1; JPH05502262A

Abstract

On utilise des diesters d'acide benzoïque, fluides à la température ambiante, de diols à chaîne droite et/ou ramifiée ayant au moins 4 atomes de carbone comme solvants peu volatils, non polluants, de substances actives, telles que des inhibiteurs de la corrosion et/ou de l'oxydation, ayant au moins en partie une structure moléculaire aromatique, lorsque ces substances actives sont ajoutées à des graisses et/ou à des huiles à biocompatibilité élevée, notamment des huiles hydrauliques à base d'huiles-esters.Diesters of benzoic acid, which are fluid at room temperature, of straight chain and / or branched diols having at least 4 carbon atoms are used as non-volatile, non-polluting solvents, of active substances, such as corrosion inhibitors. and / or oxidation, having at least partly an aromatic molecular structure, when these active substances are added to fats and / or oils with high biocompatibility, in particular hydraulic oils based on ester oils.

Description

"Non-volatile solvent for active ingredients containing aromatics"

The invention relates to an improvement in the field of the use of oils, for example as hydraulic fluids for hydrostatic power transmission.

In areas of application in which oil leaks into the environment are to be included as a possibility, for example due to leaks which cannot be prevented, the use of hydraulic oils which contain environmentally friendly ester oils, in particular those based on rape oil and / or soybean oil, is increasingly being demanded today . Typical areas of application of the area concerned here are the machines and implements of forestry, agriculture, excavators and the like. The use of hydraulic oils of water hazard class 0 is required here today. In contrast to the hydraulic oils based on mineral oil used in the past, corresponding oils based on esters are suitable to meet today's requirements for environmental compatibility.

However, the ester oils that can be used in practice, for example rapeseed oils and / or soybean oils that have been freed from mucilage, show decisive weaknesses compared to mineral oils:

The ester oils based on unsaturated fatty acid systems tend to thicken rapidly even at only moderately elevated operating temperatures of, for example, 50 to 80 ° C. The reason for this is the willingness of the olefinic double bonds of the ester-forming acids of the oil type affected here to react under the influence of atmospheric oxygen, which ultimately leads to Increase viscosity. It is generally known that such undesirable increases in viscosity can be retained to a certain extent, especially in hydraulic oils, by adding antioxidants. Nevertheless, it is difficult to set a satisfactory level of performance here, in particular for working over longer periods. Often there is a need to replenish antioxidants, corrosion inhibitors and the like after a certain period of use in order to ensure a sufficiently long operating period for ester oils of the type concerned here.

The auxiliaries required here from the classes of antioxidants, corrosion inhibitors and the like are frequently, if not usually, compounds which contain at least a proportion of aromatic constituents. In particular, phenolic structures and / or hydroquinone derivatives are predominant in the class of auxiliaries or active substances concerned here against undesirable attack by atmospheric oxygen. For example, in the earlier patent application P 39 27 155.2 (D 8826 "Environmentally friendly base oil for the formulation of hydraulic oils") the applicant describes a corresponding base oil based on natural substances for the formulation of hydraulic oils with improved viscosity and / or low-temperature stability in use, which contains the following components:

a) purified rapeseed oil and / or soybean oil as the main oil component, b) 0.5 to 5% by weight, based on the mixture as a whole, of antioxidants selected from the group: methoxyphenol, ethoxyphenol, butylhydroxyanisole, butylhydroxytoluene, methoxy- hydroquinone, ethoxyhydroquinone, tert. -Butylhydroquinone and / or tocopherol and if desired c) esters of trimethylolethane, trimethylolpropane and / or neopentylglycol with monocarboxylic acids of the following subclasses d) saturated C_monocarboxylic acids and / or c2) fatty acids based on rapeseed oil, soybean oil and / or technical oleic acid, the ester components to c) being at most approximately equal in quantity the main oil component to a) are present.

Antioxidants based on aromatic molecular constituents are used throughout as component (b). For practical work with such environmentally friendly base oils, it proves desirable to additionally provide active ingredient concentrates which contain the stabilizing additives - preferably in high concentrations - in solution. The service life of the hydraulic oil can be extended effectively by replenishing these additives. However, there is a certain problem here in the choice of the solvent. Active substance concentrates of the type described require a solvent which is flowable at ambient temperature and has a low volatility and is highly compatible with the aromatic basic structure of the active substances used in order to ensure the required high concentrations of the dissolved active substances. A likewise aromatic basic structure of the solvent fulfills this requirement. Based on these considerations, dibutyl phthalate (DBP), which is widely used today, would be a suitable representative as a solvent for the preparation of the active ingredient concentrates required here. Recently, however, certain ecological and toxicological concerns about the uncontrolled use of DBP have become known in the literature. This is where the invention comes in.

The invention is based on the object for the operation of environmentally friendly oil phases, such as those used as ester oils it is known from the applicant's older patent application mentioned to provide auxiliaries of the type also described at the beginning with at least a proportion of aromatic molecular structure, which in turn are characterized by high environmental compatibility. In particular, the invention seeks to make it possible to make antioxidants and / or corrosion inhibitors of the type described available as dissolved concentrates in a solvent which itself can be assigned to water hazard class 0, while at the same time producing highly concentrated, more flowable at ambient temperature Solutions made possible and can be mixed into the ester-based hydraulic oils without any special effort and without hesitation.

The technical solution to the problem according to the invention lies in the use of selected benzoic acid diesters as a non-volatile solvent of high environmental compatibility.

The invention accordingly relates to the use of selected, straight-chain and / or branched aliphatic diols which flow at ambient temperature and have branched aliphatic diols with at least 4 C atoms as a non-volatile, environmentally friendly solvent for active substances such as oxidation and / or corrosion inhibitors with at least partially aromatic molecular structure in them Use in fats and / or oils with increased environmental compatibility, in particular in hydraulic oils based on ester oil.

In a further embodiment, the invention relates to an additive containing active ingredients such as antioxidants and / or corrosion inhibitors with an at least partially aromatic basic structure based on a low-volatile solvent which is free-flowing at room temperature and which is characterized in that the benzoic acid diester which is free-flowing at ambient temperature is straight-chain and / or branched aliphatic diols with at least 4 carbon atoms. Preferred non-volatile solvents for the purposes of the invention are diol diesters of benzoic acid which have pour points below 0 ° C. and preferably below -10 ° C. and at the same time have flash points not below 150 ° C. and preferably above 200 ° C. Benzoic acid diesters of this property profile are derived in particular from diols which have 4 to 9 C atoms and in particular 5 to 7 C atoms in a linear arrangement between the hydroxyl groups of the diol and. Have diol components in the ester. This linear intermediate member of the diols can be unsubstituted or can be branched once or several times, in which case substitution with lower alkyl radicals with preferably up to a maximum of 3 carbon atoms is suitable. Particularly suitable are diesters of benzoic acid of those diols which have a maximum of 10 carbon atoms in the diol radical.

Di-benzoic acid esters of the type described here show, in the sum of their properties, the requirement profile described at the outset. Because of their aromatic molecular component, esters of this type can absorb large amounts of the aromatic active ingredients to be dissolved in the additive. As a rule, active substance contents in the range from 5 to about 50% by weight, preferably in the range up to about 40% by weight. % can be set in the selected solvent type. The benzoic acid esters themselves are environmentally compatible and, in particular, correspond to water hazard class 0. Their entry and homogeneous mixing into hydraulic oils, for example based on the ester oils described, succeed without any problems.

Preferred active ingredients for use via the additives according to the invention are antioxidants selected from the group consisting of methoxyphenol, ethoxyphenol, butylhydroxyanisole, butylhydroxytoluene, methoxyhydroquinone, ethoxyhydroquinone, tert-butylhydroquinone and / or tocopherol. In addition, other conventional active ingredients can be added to the additive concentrates. Examples of these are high-pressure additives, wear protection additives and / or pour point depressants. For more details on the composition of hydraulic oils, reference is made to the relevant prior art publication. Special mention should be made here of "Ulimann's Encyclopedia of Technical Chemistry" 4th edition (Verlag Chemie, Weinheim) Volume 13, page 85 ff., Hydraulic fluids and Dieter Klamann "Lubricants and related products", production, properties, application, (Verlag Chemie , Weinheim) 1982, pages 147/148 - 11.9. Hydraulic oils.

In a particular embodiment of the invention, the benzoic acid diesters are used in admixture with polyalphaolefins as the solvent phase. The term "the" polyalphaolefins encompasses oligomers of alpha olefins of a medium chain length. Oligomers which meet the theological requirements imposed on the benzoic acid diol diesters are particularly suitable here. I n particular suitable are Oligo¬ mers of alpha olefins having 6 to 12 carbon atoms in the monomeric Mo¬ lekül, with particular importance _for the oligomers of C _1. Alpha-olefin have. The oligomers can in turn be formed, for example, from 2 to 6 units of the alpha olefin. The benzoic acid diesters can be used with the polyalphaolefins in a wide mixing ratio, so that quantitative ratios of the two components to one another in the range from about 95: 5 to 5:95 and preferably those in the range from about 70: 30 to 30: 70 in Can come into consideration. Examples

example 1

856 g of pentanediol (1.5) were esterified with 1832 g of benzoic acid in the presence of 0.1% tin oxide at 200 ° C. for 7 hours. A colorless, clear-liquid oil was obtained with the following key figures: acid number: 0.3, hydroxyl number: 29, saponification number: 350. The flash point of this oil according to DIN ISO 2592 was 224 ° C., the pour point according to DIN ISO 3016 was -33 ° C, the cloud point according to DIN ISO 3015 at -12 ° C.

Comparative Example 1

159 g of neopentyl glycol, 136 g of trimethylolpropane and 366 g of benzoic acid were converted into an ester as in Example 1. A colorless oil was obtained which crystallized after about 3 days.

Comparative Example 2

183 g of benzoic acid and 76 g of propanediol (1,2) were converted into an ester as in Example 1. A crystalline product was obtained.

Example 2

30 g of butylated hydroxyanisole were dissolved in 70 g of the ester according to Example 1 at 60 ° C. This mixture remained liquid at -10 ° C for 3 weeks. Comparative Example 3

342 g of trimellitic anhydride, 323 g of octanol and 485 g of decanol were converted to an ester as in Example 1. A colorless oil was obtained with the following characteristics: acid number: 0.5, hydroxyl number: 2, saponification number: 285. The pour point according to DI N ISO 3016 was -42 ° C, the flash point according to DI N ISO 2592 was 280 ° C.

Analogously to Example 2, 30 g of butylated hydroxyanisole were dissolved in 70 g of the ester according to Comparative Example 3 at 60 ° C. When the mixture was cooled to room temperature, the butyl hydroxy anisole crystallized again.

Claims

Patent claims

1 . Use of selected straight-chain and / or branched aliphatic diols with at least 4 C atoms and flowable at ambient temperature as a low-volatility, environmentally friendly solvent for active substances such as oxidation and / or corrosion inhibitors with at least partially aromatic molecular structure when used in fats and / or oils with increased environmental compatibility, in particular hydraulic oils based on ester oil.

2. Embodiment according to claim 1, characterized in that benzoic acid diol diesters with pour points below 0 C, preferably below - 10 ° C and flash points not below 150 C, preferably above 200 ° C, which are preferably 4 to 9 C- Have atoms, in particular 5 to 7 carbon atoms in a linear arrangement between the hydroxyl groups of the esterified diols, it being possible for this linear intermediate member to be substituted 1 or more times with lower alkyl radicals, preferably with up to 3 carbon atoms.

3rd embodiment. according to claims 1 and 2, characterized in that the diesters of benzoic acid are used to produce highly concentrated active ingredient solutions, the active ingredient contents of which are preferably in the range from about 5 to 40% by weight.

4. Embodiment according to claims 1 to 3, characterized gekenn¬ characterized in that benzoic diesters of diols having a maximum of 10 carbon atoms are used as solvents.

5. Embodiment according to claims 1 to 4, characterized gekenn¬ characterized in that the benzoic acid diesters are mixed with polyalphaolefins in a ratio of 95: 5 to 5: 95.