WO1985003306A1

WO1985003306A1 - Hardly inflammable, biologically degradable functional liquid

Info

Publication number: WO1985003306A1
Application number: PCT/DE1985/000020
Authority: WO
Inventors: Helmut Theunissen; Raymund Weber
Original assignee: Hydrocor Forschungs-Und Analytik Gmbh
Priority date: 1984-01-27
Filing date: 1985-01-25
Publication date: 1985-08-01
Also published as: HUT37646A; AU573782B2; HU194300B; DK418785A; EP0150826A2; FI78499B; ZA85638B; ATE43628T1; DK418785D0; DE3402863A1; AU3930885A; FI853708A0; FI853708L; EP0150826B1; CA1244054A; FI78499C; JPS61501035A; EP0150826A3; DE3570692D1

Abstract

Hardly inflammable and biologically degradable functional liquid comprising at least one bromine-containing benzyl toluol derivative having the general formula (I) wherein x is 1 or 2, x' is 0 or 1, y is 0, 1 or 2, y' is 0, 1 or 2, z is 0 or 1 and z' is 1 or 2, providing that the equations y + y' = 0, 1 or 2 and x + x' + y + y' = 1, 2 or 3 are verified.

Description

Flame retardant, biodegradable functional liquid

Description

The invention relates to a flame-retardant, biodegradable functional fluid, in particular a hydraulic fluid or an insulation fluid for electrical devices, which contains a bromine-containing benzyltoluene derivative as an essential component.

Chlorinated aromatics, especially chlorinated biphenyls, have played an important role in a wide range of technology in recent decades. In particular, the polychlorinated biphenyls have been widely used as hydraulic fluids, as insulation fluids for electrical systems and as flame retardant additives for plastics and the like. In the meantime, however, these connections have been badly discredited. Serious health and environmental effects of these products have been identified, and catastrophic hazards are possible if there is a fire, as this can form highly toxic dioxins and dibenzofurans. This has resulted in the fact that the production or at least the use of such compounds has already been completely banned by the state supervisory bodies and that severe restrictions have been imposed on the use of these substances.

To overcome these disadvantages, it is proposed in European Patent Application No. 88 650 to use chlorinated benzyltoluenes and chlorinated benzyloxylols as lubricants, which can also be used as hydraulic fluids, since these compounds are flame-retardant and resistant to oxidation and are also biodegradable and with regard to their toxic behavior should have advantages.

GB-PS 1 504 655 describes electrical devices which contain readily biodegradable dielectric liquids, namely halogenated diphenylmethanes, which are characterized in that the halogen substituents and any alkyl substituents are only present in one of the two phenyl rings, while the other phenyl ring must be unsubstituted, since it is stated that only those halogenated diphenylmethanes which have an unsubstituted phenyl group can readily be biodegraded, while the diphenylmethanes substituted on both phenyl radicals are intended to resist microbiological degradation.

EP-OS 8251 discloses liquid dielectrics which can be used, for example, as insulating liquids for transformers or as impregnating agents for capacitor insulator layers. These are essentially chlorinated alkylaromatic compounds which have been obtained from chlorotoluene and / or chloroxylene, such as, for example, tetrachlorobenzyltoluene, which are said to have advantages over the polychlorinated biphenyls used hitherto for the same purpose. The absence of the biphenyl nuclei and the presence of the alkyl groups on the aromatic nuclei are assigned a favorable effect on the biodegradation behavior.

Finally, European patent application No. 71 338 describes electroviscous liquids which consist of hydrophobic liquids in which solid hydrophilic particles are dispersed. When an electric field is applied to such a suspension, the viscosity of this mixture increases drastically. This change is reversible and rapid, so that such suspensions are used, for example, in electronically controllable clutches can be. It is stated that the hydrophobic liquid present in the mixture has a high boiling point, a low viscosity, sufficient electrical properties and should be chemically stable and, furthermore, should be low in toxicity and preferably biodegradable. To this

According to the teaching of this European patent application, halogenated diaryl derivatives are used as hydrophobic liquids, the aromatic nuclei of which are connected to one another by a wide variety of bridges and may have fluorine, chlorine or bromine atoms as halogen substituents. It is stated that these diaryl derivatives should be substituted asymmetrically, since this would result in a low freezing point of the liquid and an improvement in the biodegradability of the material.

The functional fluids known from the prior art cannot fully satisfy because they either do not meet the criteria of the low flammability of hydraulic and insulation fluids or, given the low flammability, have disadvantageous properties such as poor biodegradability, toxicity of the fluid or its decomposition products, unfavorable viscosity properties. Have temperature behavior or incompatibility with sealing elements.

The object of the present invention is to provide functional liquids which have all the physical properties required for the intended use and which can be biodegraded at the same time with high chemical stability, are largely non-toxic and do not become highly toxic products, such as dioxins, even if handled improperly , to lead.

Surprisingly, it has been shown that a certain group of halogenated diaryl derivatives is not only based on on the one hand have valuable technical properties, but on the other hand do not have the dangerousness and the environmentally harmful effects of the known compounds, so that they are particularly suitable as or for functional liquids.

The invention therefore relates to the flame-retardant, biodegradable functional liquid according to the main claim. The subclaims relate to particularly preferred embodiments of this subject matter of the invention.

The invention accordingly relates to a flame-retardant, biodegradable functional liquid, consisting of or containing at least one bromine-containing benzyltoluene derivative of the general formula I.

in which x 1 or 2, x '0 or 1, y 0, 1 or 2, y' 0, 1 or 2, z 0 or 1 and z '1 or 2 with the proviso that the relationships

y + y '= 0, 1 or 2 and x + x' + y + y '= 1, 2 or 3

are fulfilled.

In the bromine-containing benzyltoluene derivatives used according to the invention as or in functional liquids it is therefore a question of compounds which are substituted on both nuclei, at least one bromine substituent and one methyl group having to be present as the substituent. However, the two nuclei can carry several bromine atoms and several methyl groups, the positions of these substituents being not essential, so that, according to the invention, all positional isomers of these bromine-containing benzyltoluene derivatives of the above general formula I can be used in or as functional liquids.

In addition, chlorine atoms can be present as substituents in one or both phenyl groups.

Surprisingly, it has been found that these bromine-containing benzyltoluene derivatives used according to the invention have a considerably more favorable environmental compatibility than the halogenated diaryl derivatives known from the prior art, and at the same time have excellent physical properties which are suitable for functional purposes

Make liquids such as hydraulic fluids or insulation fluids particularly well suited for electrical devices.

Surprisingly, it has further been found that the bromine-containing benzyltoluene derivatives of the general formula I given above which are substituted on both phenyl rings and which are used according to the invention can readily be biodegraded, which in view of the above-mentioned European patent application No. 71 338 and GB PS 1 504 655 is to be regarded as surprising. In addition, these bromine-containing benzyltoluene derivatives of the above general formula I used according to the invention have the further surprising advantage that they are liquid under normal conditions of use and have a particularly favorable viscosity-temperature behavior. In addition, they have a high flash point, are not very toxic, are not very corrosive and also cause improper overheating does not result in the highly toxic dioxin products that have occasionally occurred in accidents with polychlorinated biphenyls. In addition, it has been shown that the bromine-containing benzyltoluene derivatives used according to the invention also have excellent sealing element compatibility, so that the group of compounds selected according to the invention has proven to be surprisingly advantageous for the intended field of use.

Flame-retardant, biodegradable functional liquids which contain a compound of the general formula II as a bromine-containing benzyltoluene derivative are particularly preferred

included, in which x 'is 0 or 1, z is 0 or 1 and z' is 1 or 2.

The functional liquids according to the invention which contain a bromine-containing benzyltoluene derivative of the following formulas III, IV or V are even more preferred

contain ,

Of course, the functional liquids according to the invention can contain the bromine-containing benzyltoluene derivatives defined above individually, but preferably in the form of mixtures, especially in the form of mixtures of the individual positional isomers of these compounds.

The bromine-containing benzyltoluene derivatives of the formulas given above selected according to the invention and used in or as functional liquids are known in some cases, for example by the general formula of the European patent application No. 71 338 already mentioned above or else by the generic definition of DE-OS 23 36 289. The first cited literature provides an immensely large group of compounds and does not address the expressis verbis used in the invention or in the examples. DE-OS 23 36 289 describes essentially chlorinated o-benzyltoluenes, which are described as valuable starting materials for the production of anthracene and anthraquinone and their derivatives. The compounds of the above general formulas selected and used in accordance with the invention differ from the biodegradable bromine-containing benzyltoluene derivatives described in British Pat. No. 1,504,655 in that they are not asymmetrical but are substituted on both phenyl rings and nevertheless have surprisingly advantageous properties.

The bromine-containing benzyltoluene derivatives used according to the invention are prepared in a manner known per se either by halogenating the corresponding non-halogen-substituted benzyltoluenes with elemental bromine or a mixture of bromine and chlorine in the presence of a known halogenation catalyst such as iron, FeCl ₃ , FeBr ₃ , AlCl ₃ , TiCl ₄ and the like. The reaction can be carried out at room temperature, but depending on the particular catalyst, temperatures between -5 and + 40 ° C. are also suitable.

Another preferred procedure for the preparation of the bromine-containing benzyltoluene derivatives of the above general formula I used according to the invention consists in the condensation of a compound of the general formula VI

wherein x ', y' and z 'have the meanings given above, with a compound of the general formula VII

wherein Hal is bromine or chlorine and x, y and z have the meanings given above. The condensation is carried out, if appropriate, in the presence of a Friedel-Crafts catalyst, such as, for example, FeCl ₃ , FeBr ₃ , AlCl ₃ and / or TiCl ₄ , with an excess of compounds of the general formula VI.

Compared to that from the European patent application

No. 88 650 known chlorine-substituted compounds zei The bromine-containing benzyltoluene derivatives used according to the invention have a substantially improved flame retardancy with a simultaneously improved viscosity-temperature behavior.

The asymmetrically substituted dibromobenzyltoluene known from GB-PS 1 504 655 solidifies at room temperature, while the isomer brominated on both phenyl rings only solidifies at -25 ° C., which is particularly advantageous for the use of this compound as a hydraulic fluid or insulating fluid.

Thus, the bromine-containing benzyltoluene derivatives used in accordance with the invention have proven themselves not only in the case of hydraulic fluids but also in the case of insulation fluids for electrical devices, such as, for example, capacitors, transformers and the like, not only because of their favorable viscosity-temperature behavior but also because of their very favorable flame-retardant action. The functional fluids according to the invention can therefore in particular also be used as flame-retardant hydraulic fluids or flame-retardant insulation fluids which, because of their low toxicity, their low tendency to form toxic decomposition products and their biodegradability, represent a significant enrichment of technology.

As already mentioned, instead of the individual compounds in the functional liquids according to the invention, the bromine-containing benzyltoluene derivatives mentioned may be present individually or in the form of mixtures, in particular in the form of the isomer mixtures.

The invention is described in more detail below with the aid of examples. Manufacturing example

Production of dibromobenzyltoluene by condensation of bromotoluene with bromobenzylbromide

To prepare dibromobenzyltoluene, bromination of toluene with elemental bromine is first carried out in the presence of anhydrous FeCl ₃ bromotoluene, which is then brominated on the side chain. For this purpose, 8.3 mol of bromotoluene are heated to 80 ° C. in the presence of 0.5 g of a radical chain initiator (α, α ′ -azobisisobutyronitrile). Under irradiation with an ultraviolet lamp with a power of 300 W, 1.66 mol of bromine are added dropwise with cooling. The resulting hydrogen bromide is absorbed in a wash bottle with chilled water.

The cooled mixture is then added dropwise to a condensation reaction in a suspension of 6 g FeCl ₃ in 1.66 mol bromotoluene at a temperature of 30 ° C. The resulting gaseous hydrogen bromide is absorbed in the same way as described above with chilled water in a wash bottle. In this condensation reaction, the formation of by-products (brominated dibenzyltoluene) is suppressed by the large excess of bromotoluene used. After the addition has ended, the mixture is heated to 50 ° C. for 30 minutes, whereupon the cooled reaction mixture is washed with 1 liter of water, then with 1 liter of 10% sodium hydroxide solution and then again with 1 liter of water. The organic phase is dried and the excess bromotoluene is distilled off.

The remaining liquid is rectified at 0.4 mbar, giving 395 g of a main fraction boiling between 155 and 166 ° C. at 0.4 mbar, which is identified by mass spectrometry as dibromobenzyltoluene. An isomer study was not carried out. The table below shows the electron current mass spectrum of the dibromobenzyltoluene obtained.

The other bromine-containing benzyltoluene derivatives used in accordance with the invention are obtained in a manner analogous to the procedure described above, using methods known per se or also by direct bromination or bromination and chlorination of benzyltoluene, in which case, however, reaction mixtures are obtained which are suitable, for example by gas chromatography, must be separated into the bromine-containing benzyltoluene derivatives of the general formulas given above used according to the invention.

In addition to the bromine-containing benzyltoluene derivative, the flame-retardant, biodegradable functional liquids according to the invention can also contain additional constituents and which are customary for the functional liquids

Contain additives, for example anticorrosive agents, such as alkaline earth metal sulfonates, stabilizers, such as amine derivatives or phenolic products, wear-reducing additives, for example zinc dialkyldithiophosphates, acid acceptors, for example epoxy compounds, tetraphenyltin, etc., and defoamers, such as soap, silicones, glycols, phosphate esters, and viscosity index methacrylate esters, and viscosity index methacrylate acrylate, and polymethyl index acrylate Polyisobutylene. Furthermore, the bromine-containing benzyltoluene derivatives used according to the invention can be modified with many suitable products, such as mineral oil, glycols, etc.

The following examples serve to further illustrate the flame-retardant, biodegradable functional liquids according to the invention.

Example 1

Investigation of the properties of the invention preferably used as a bromine-containing benzyltoluene derivative ten dibromobenzyltoluene

a) Biodegradability

The biodegradability is examined with the aid of a recognized measuring method for determining the biodegradability of anionic and nonionic synthetic surfactants, namely the OECD screening test (Federal Law Gazette 1 (1977), page 245) (modified) for nonionic surfactants.

Aerobic, polyvalent microorganisms from the drain of a biological sewage plant are used as the vaccine suspension.

With this method, the first sample is taken after 7 days, the second after 14 days and the third after 19 days. The samples taken were processed in accordance with the instructions of the test described above and the rate of degradation was determined by gas chromatography.

The following result was shown:

Sample after 7 days: 49.3% degraded Sample after 14 days: 69.1% degraded

Sample after 19 days: 82.9% degraded

Surprisingly, more than 80% of the dibromobenzyltoluene used according to the invention can be biodegraded.

b) Fire investigation

The fire test is carried out according to the "6th Luxembourg report on requirements and tests of flame-retardant liquids for hydraulic power transmission carrying and control ".

It has been shown here that dibromobenzyltoluene exhibits better fire behavior than, for example, tetrachlorobenzyltoluene or polychlorinated biphenyl.

c) Investigation of the corrosion effect

The corrosion effect of dibromobenzyltoluene was investigated using the method of the 6th Luxembourg report mentioned above. For this purpose, two-thirds of the metals steel, copper, brass, aluminum, cadmium and zinc as well as the metal pairings copper-zinc, steel-aluminum, steel-cadmium and aluminum-zinc were immersed in the liquid to be tested (dibromobenzyltoluene) and in it for 28 days leave at a temperature of 35 ° C.

This investigation has shown that the weight difference caused by corrosion is less than 1 mg for all test sheets (permissible weight difference 20 mg).

d) Compatibility with sealing elements

To investigate the compatibility with sealing elements, a sealing element made of the sealing material 83 FKM 575 (Viton) is immersed in the liquid to be examined, for 21 days at 60 ° C, 80 ° C, 100 ° C, 120 ° C and 150 ° C . The change in volume of the sealing element and the change in its Shore hardness are then determined.

In this investigation, the bromine-containing benzyltoluene derivative, namely dibromobenzyltoluene, which is preferably used according to the invention, exhibits particularly good behavior as such and also in fully formulated hydraulic fluids, in that the volume change in the sealing material is between <1 and 2% and the change in Shore hardness is -3 degrees. A change in volume of up to 20% and a change in Shore hardness of -10 degrees is permissible with this test method.

The investigated comparative products based on polychlorinated biphenyl and tetrachlorobenzyltoluene show volume change values of 40% at an investigation temperature of 150 ° C. With these conventional products, when used as a hydraulic fluid, care must be taken that temperatures of 100 ° C are not exceeded, otherwise the sealing materials will be attacked to an excessive extent and malfunctions may occur.

e) Examination of pyrolysis

To test for highly toxic decomposition products, dibromobenzyltoluene was pyrolyzed at temperatures between 150 and 700 ° C. The sample is processed according to EPA method no. 613. When analyzing with GCMS, no highly toxic dioxin or dibenzofuran (tri- and tetrabrominated) was found within the detection limit (0.5 ppb).

f) Investigation of the viscosity-temperature behavior

The hydraulic fluid according to the invention according to Example 2 below shows the following viscosity-temperature behavior:

-20 ° C 8320 cSt.

0 ° C 430 cSt.

+ 20 ° C 83 cSt.

+ 50 ° C 21 cSt.

+ 100 ° C 6.6 cSt.

A hydraulic fluid based on tetrachlorobenzyltoluene has the following behavior:

-20 ° C solid, not measurable

0 ° C 9730 cSt.

+ 20 ° C 320 cSt.

+ 50 ° C 25 cSt.

+ 100 ° C 4 cSt. The following examples 2 to 8 serve the further Er purification of the invention and relate to the formulations of flame-retardant hydraulic fluids (Examples 2 to 6) and insulation fluids (Examples 7 and 8).

Example: 2

Composition of a flame-retardant hydraulic fluid:

93% dibromobenzyltoluene

6% viscosity index improver (polymethacrylate) 0.5% corrosion protection agent (barium sulfonate) 0.5% wear protection additive (zinc dialkyldithiophosphate)

Example 3

Composition of a flame-retardant hydraulic fluid:

75% dibromobenzyltoluene

23% isopropylated triphenyl phosphate

1% anti-corrosion agent (alkyl sulfamidocarboxylic acid)

1% acid acceptor (epoxy resin)

Example 4

Composition of a flame-retardant hydraulic fluid:

88% dibromobenzyltoluene

10% butyl stearate

1% corrosion protection agent (fatty acid alkanolamide) 0.5% oxidation stabilizer (amine derivative) 0.5% wear protection additive (zinc dialkyldithiophosphate) Example 5

Composition of a flame retardant hydraulic fluid:

65% dibromobenzyltoluene

25% monobrominated benzyltoluene

9% viscosity index improver (polyisobutylene)

1% anti-corrosion agent (tallow fat amine derivative)

Example 6

Composition of a flame-retardant hydraulic fluid:

50% dibromobenzyltoluene

45% monobrominated xylylxylene

4.5% viscosity index improver (polyisobutylene)

0.5% anti-corrosion agent (tallow fat amine derivative)

Example 7

Composition of an insulation liquid for electrical devices:

99.5% dibromobenzyltoluene 0.3% anti-corrosion agent (tallow fatty amine derivative) 0.2% epoxy resin

Example 8

Composition of an insulation liquid for electrical devices:

50% dibromobenzyltoluene

49.5% monobrominated benzyltoluene 0.3% anti-corrosion agent (tallow fat amine derivative) 0.2% epoxy resin

Claims

Patent claims

1. Flame-retardant, biodegradable, functional liquid consisting of or containing at least one bromine-containing benzyltoluene derivative of the general formula I

y + y '= 0, 1 or 2 and x + x' + y + y '= 1, 2 or 3

are fulfilled.

2. Functional liquid according to claim 1, d a d u r c h g e k e n n z e i c h n e t that it as a bromine-containing benzyltoluene derivative a compound of general formula II

in which x 'is 0 or 1, z is 0 or 1 and z' is 1 or 2.

3. Functional liquid according to claim 1, d a d u r c h g e k e n n z e i c h n e t that it as a bromine-containing benzyltoluene derivative a dibromobenzyltoluene of the general formula III

contains.

4. Functional liquid according to claim 1, d a d u r c h g e k e n n z e i c h n e t that it as a bromine-containing benzyltoluene derivative a monobromxylylxylene of the general formula IV

contains.

5. Functional liquid according to claim 1, d a d u r c h g e k e n n z e i c h n e t that it as a bromine-containing benzyltoluene derivative. a monobromobenzyltoluene of the formula V

contains.

6. Functional liquid according to claims 1 to 5, and that it is present in the form of a hydraulic fluid which contains at least 35% by weight of the bromine-containing benzyltoluene derivatives and, if appropriate, customary additives for hydraulic fluids.

7. Functional liquid according to claims 1 to 5, characterized in that it is in the form of an insulation liquid for electrical devices containing at least 35 wt .-% of the bromine-containing benzyltoluene derivatives and ge possibly contains customary additives for electrical insulation liquids.