Hydraulic fluid composition

Description

[0001] The present invention relates to a hydraulic fluid composition and in particular to a brake fluid composition.

[0002] The preparation is known of hydraulic fluids based on glycol ethers and/or based on boric esters of glycol ethers. These hydraulic fluids most often contain additives, in particular corrosion-inhibiting or oxidation inhibiting additives and a neutralizing agent.

[0003] The preparation is known of hydraulic fluids containing amines as corrosion-inhibiting additives and/or as neutralizing agents. In particular, the use is known, according to European Patent Application EP-A-454 110 and Patent US 3 711 410, of alkanolamines. However, it was observed that these alkanolamines do not make it possible to prepare hydraulic fluids of high boiling point which simultaneously have a number of specific characteristics. In particular, they do not make it possible to prepare hydraulic fluids having a desired viscosity and optionally a desired volatility as a function of the boiling point, while moreover having good compatibility with elastomers of styrene butadiene rubber (SBR) type, a basic pH and good corrosion-inhibiting properties.

[0004] The present invention relates to a high boiling point hydraulic fluid composition which makes it possible to solve the problems mentioned above.

[0005] The subject of the present invention is thus a hydraulic fluid composition based on at least one glycol ether or on at least one boric ester of a glycol ether or a mixture of the two, characterised in that it contains, as additive, at least one ether-amine having a molecular weight between 120 and 300 and having the following formula:

in which R₃ is linear or branched radical having at least one ether functional group and no alcohol functional group, R is a methyl radical or a hydrogen atom, p is an integer from 1 to 3 and q is an integer from 0 to 2.

[0006] According to the present invention, the composition contains an ether-amine used essentially as a corrosion-inhibiting additive and/or a neutralizing agent. This ether-amine has a molecular weight between 120 and 300. When an ether-amine is used which has a lower molecular weight, a composition is obtained which is volatile and which has a low boiling point. Moreover, when an ether-amine is used which has a greater molecular weight, a composition is obtained which has an excessively high viscosity. The molecular weight of the ether-amine is preferably from 150 to 250.

[0007] According to the invention, the ether-amine used must contain a radical R3 which is a linear or branched radical having at least one ether functional group and no alcohol functional group. Thus radical R3 is not cyclic.

[0008] According to one particular embodiment of the invention R3 has the following formula R1-O-R2- in which R1 is a linear or branched alkyl radical preferably having from 1 to 5 carbon atoms and R2 is a linear or branched alkylene radical preferably having from 2 to 8 carbon atoms.

[0009] The ether-amine comprises at least one and preferably at least 2 units derived from an epoxide. Very advantageously, p+q ranges from 1 to 3. It is preferred to have p + q = 2. Furthermore, it is also advantageous to use a mixture comprising by weight from 85 to 95 % of an ether amine having p + q = 2 and from 15 to 5 % of an ether-amine having p + q = 3.

[0010] The ether-amine is generally obtained by reacting a starting ether-amine, with an epoxide such as, for example, ethylene oxide, propylene oxide or a mixture of the two.

[0011] A particularly advantageous starting ether-amine can have the following general formula (A):

        R₁-O-R₂-NH₂

in which R₁ and R₂ have the same meaning as above. The ether-amine obtained advantageously contains the amines having the following formula (B):

in which R₁, R₂, R, p and q have the same meaning as above. In practice, a mixture of ether-amines having the formula (B) is obtained. It is desirable to obtain essentially the amine having the formula (B) in which p = 1 and q = 1.

[0012] The hydraulic fluid composition according to the invention most often contains, by weight, between 0.5 and 5 %, and preferably between 1 and 4 %, of the ether-amine.

[0013] The composition of the invention has generally a viscosity measured at 40°C equal to or less than 10 mm2/s, and preferably comprised between 2 and 8 mm2/s. It essentially consists of at least one glycol ether such as, for example, butyl triglycol ether, ethyl triglycol ether or methyl triglycol ether, or most often of at least one boric ester of a glycol ether such as, for example, the boric ester of methyl triglycol ether or further of a mixture of the two. When the hydraulic fluid contains a boric ester, the amine of the invention is an excellent neutralizing agent.

[0014] The composition can contain the usual additives of hydraulic fluids. In particular, it can contain, in addition to the amine, a corrosion-inhibiting additive, such as benzotriazole, tolyltriazole, an alkali metal or alkaline-earth metal nitrate, triphenyl phosphite, or dodecenylsuccinic anhydride. It can also contain an oxidation-inhibiting additive such as bisphenol A or polymerized trimethylquinoline.

[0015] A composition according to the invention can advantageously contain, by weight:

a) from 60 to 95 % of boric ester of the monomethyl ether of triethylene glycol,

b) from 1 to 15 % of monomethyl ether of triethylene glycol,

c) from 0 to 15 % of monobutyl ether of triethylene glycol and

d) from 0.5 to 5 % of an ether-amine according to the invention.

[0016] The amine used makes it possible to more particularly obtain compositions having an equilibrium reflux boiling point (E.R.B.P.) equal to or greater than 270°C, e.g. from 270 to 295°C, and simultaneously a kinematic viscosity, measured at - 40°C, equal to or less than 1100 mm2/s, e.g. from 900 to 1100 mm2/s, while having a low volatility which is characterized by a small variation in the pH and in the reserve alkalinity (RA) after having been subjected to an evaporation test. It also makes it possible to obtain compositions having an E.R.B.P. equal to or greater than 300°C, e.g. from 300 to 310°C, while having a kinematic viscosity, measured at - 40°C, equal to or less than 1400 mm2/s, e.g. from 1250 to 1400 mm2/s. Moreover, all these compositions have a pH between 7 and 9 and preferably between 7.5 and 8.5, a good compatibility with elastomers and good corrosion-inhibiting properties, especially with respect to ferrous alloys or metals.

[0017] The composition according to the invention is particularly suited to the manufacture of brake fluids of DOT 3 type (DOT signifying Department of Transportation U.S.A.) and preferably of DOT 4 or DOT 5.1. These brake fluids can be used very advantageously in the brake circuits of competition cars, in particular when they have an E.R.B.P. equal to or greater than 300°C.

Measurement of the E.R.B.P.

[0018] The E.R.B.P. of a hydraulic fluid is measured in °C according to the SAE standard J 1703 of June 1991.

Measurement of the pH

[0019] The pH of a hydraulic fluid is measured according to SAE standard J 1703 of June 1991.

Measurement of the reserve alkalinity

[0020] The reserve alkalinity (RA) of a hydraulic fluid is measured by the volume of 0.1 N hydrochloric acid, expressed in ml, necessary to obtain a pH of 5.5 for a 50 ml sample of hydraulic fluid. The following examples illustrate the present invention.

Examples 1 to 7

[0021] 7 hydraulic fluid compositions were prepared. Table 1 gives the compositions by weight. Composition 1, prepared according to the invention, contains 2,2'-[3(methoxypropyl)imino]bisethanol (amine (C)), which was obtained by reacting 3-methoxypropylamine with 2 moles of ethylene oxide. This ether-amine had the following composition by weight :

[0022] The other compositions are comparative and were not prepared according to the invention.

[0023] Table 2 shows, for each of the compositions 1 to 7, the following characteristics :

• the boron content in weight %,
• the pH,
• the equilibrium reflux boiling point (E.R.B.P.),
• the kinematic viscosity measured at - 40°C and expressed in mm2/s,
• the results of the SBR rubber swelling test carried out at 120°C and for 70 hours according to SAE standard J 1703 of June 1991.

[0024] Moreover, Table 2 also shows the requirements for the characteristics measured. It was observed that Composition 1 made it possible to fulfil all these requirements. Composition 5 had an excessively large swelling of the elastomers, Composition 4 had an excessively low pH and an excessively high viscosity whereas compositions 2, 6 and 7 had an excessively low E.R.B.P.

Examples 8 to 10

[0025] 3 hydraulic fluid compositions were prepared. Table 3 shows the compositions by weight. Composition 8, prepared according the invention, contained 2,2'-[3(methoxypropyl)imino]bisethanol (amine (C)) used in Example 1. The other compositions are comparative compositions which had not been prepared according to the invention. In Table 3, "additives" means a mixture containing tolyltriazole, triphenyl phosphite and polymerized trimethylquinoline. This mixture is used to obtain a hydraulic fluid containing 200 ppm of tolyltriazole, 0.1 % by weight of triphenyl phosphite and 0.02 % by weight of the polymerized trimethylquinoline.

[0026] Table 4 shows, for each of the compositions, the following measured characteristics with the requirements:

• the pH
• the ERBP in °C
• the kinematic viscosity measured at -40°C expressed in mm2/s,
• the pH measured after having carried out Evaporation Test No. 1,
• the initial reserve alkalinity,
• and the variation in this reserve alkalinity measured after having carried out Evaporation Test No. 2.

[0027] Composition No. 8 made it possible to fulfil all the requirements. Moreover, it shows the following results of SBR swelling tests carried out according to SAE standard J 1703 of June 1991:

• variation in the diameter (mm): 0.74
• variation in the volume (%): 9.95
• variation in the hardness: -11

[0028] Moreover, the results of the corrosion tests carried out according to SAE standard J 1703 are the following:

• ferrous metals: less than 0.1 mg/cm2
• aluminium: less than 0.1 mg/cm2
• copper: less than 0.1 mg/cm2

[0029] Composition 9, which contained tridecylamine, had a pH measured after Evaporation Test No. 1 of less than 7 whereas Composition 10 showed an excessively large variation in the reserve alkalinity.

[0030] In Examples 8 to 10, Evaporation Test No. 1 was carried out in the following way : 100 ml of hydraulic fluid were introduced into a 600 ml glass beaker. The beaker was then placed for 168 hours in an oven maintained at 140°C.

[0031] Evaporation Test No. 2 was carried out in the following way: 200 ml of hydraulic fluid were introduced into a 500 ml round-bottomed flask with a ground neck. This roundbottomed flask was placed for 24 hours in an oven maintained at 80°C ± 2°C and under a 2 mm mercury vacuum.

TABLE 1

Compositions in weight %	% 1	2	3	4	5	6	7
boric ester of the monomethyl ether of triethylene glycol	95.0	95.5	90.0	91.0	85.8	95.0	95.0
monomethyl ether of triethylene glycol		1.5	6.5
monobutyl ether of triethylene glycol	2.0			8.3	11.0	2.0	2.0
amine (C)	3.0
tributylamine						3.0
tridecylamine					3.2
dioctylamine			3.5
diisopropanolamine		3.0
monoethanolamine				0.7
3-methoxypropylamine							3.0

TABLE 2

Characteristics	Requirements	1	2	3	4	5	6	7
boron content		1.87	1.88	1.80	1.82	1.88	1.87	1.87
pH	from 7 to 11	7.15	7.3	7.45	6.9	7.4	7.5	8.3
ERBP (°C)	> 300	308	290	306	300	310	292	261
kinematic viscosity at -40°C(mm2/s)	<= 1400	1329	1470	1440	1500	1273
Results of the SBR swelling test
variation in the diameter (mm)	from 0.5 to 1.5	+ 1.1		+ 1.4	+ 1.1	+ 1.8
variation in the volume (%)	from 1 to 16	13		17.5	13	20.6
variation in the hardness (IRDH)	> - 15	- 8		- 13.5	- 10.5	- 16

TABLE 3

Compositions in weight %	Example 8	Example 9	Example 10
boric ester of the monomethyl ether of triethylene glycol	63.2	62.5	41.0
monomethylene ether of triethylene glycol	4.8	11.1
monobutyl ether of triethylene glycol	21.7	18.4	49.2
triethylene glycol	8.0	6.0	8.0
additives	1.0	1.0	1.0
amine (C)	1.3
tridecylamine		1.0
tributylamine			0.8

TABLE 4

Characteristics	Requirements	Example 8	Example 9	Example 10
pH	from 7 to 11	7.6	7.5	8.5
reserve alkalinity		33.6		19.6
kinematic viscosity at -40°C (mm2/s)	< 1100	1055	1082
pH after Test No. 1	> 7.0	7.3	6.2
RA variation after Test No. 2 in %	> - 10	- 1		- 51.5
ERBP (°C)	> 270	273	267	265

Claims

1. A hydraulic fluid composition based on at least one glycol ether or on at least one boric ester of a glycol ether or a mixture of the two, characterised in that it contains, as additive, at least one ether-amine having a molecular weight between 120 and 300 and having the following formula :

in which R3 is linear or branched radical having at least one ether functional group and no alcohol functional group, R is a methyl radical or a hydrogen atom, p is an integer from 1 to 3 and q is an integer from 0 to 2.

2. A hydraulic fluid composition according to Claim 1, characterised in that R3 is a group having the formula R1-O-R2- in which R1 is a linear or branched alkyl radical and R2 is a linear or branched alkylene radical.

3. A hydraulic fluid composition according to Claim 2, characterised in that R1 is a linear or branched alkyl radical having from 1 to 5 carbon atoms and R2 is a linear or branched alkylene radical having from 2 to 8 carbon atoms.

4. A hydraulic fluid composition according to any one of Claims 1 to 3, characterised in that the ether-amine has a molecular weight between 150 and 250.

5. A hydraulic fluid composition according to any one of Claims 1 to 4, characterised in that it contains, by weight, from 0.5 to 5 % of the ether-amine.

6. A hydraulic fluid composition according to any one of Claims 1 to 5, characterised in that it has a viscosity, measured at 40°C, of less than 10 mm2/s.

7. A hydraulic fluid composition containing by weight :

a) from 60 to 95 % of boric ester of the monomethyl ether of triethylene glycol,

b) from 0 to 15 % of monomethyl ether of triethylene glycol,

c) from 0 to 15 % of monobutyl ether of triethylene glycol and

d) from 0.5 to 5 % of an ether-amine and having a molecular weight between 120 and 300 and the following formula:

in which R₃ is linear or branched radical having at least one ether functional group and no alcohol functional group, R is a methyl radical or a hydrogen atom, p is an integer from 1 to 3 and q is an integer from 0 to 2.

8. A hydraulic fluid composition according to Claim 7, characterised in that R3 is a group having the formula R1-O-R2- in which R1 is a linear or branched alkyl radical having from 1 to 5 carbon atoms and R2 is a linear or branched alkylene radical having from 2 to 8 carbon atoms.

9. A hydraulic fluid composition according to any one of Claims 1 to 8, characterised in that it has an equilibrium reflux boiling point (E.R.B.P.) equal to or greater than 270°C and a viscosity measured at - 40°C, equal to or less than 1100 mm2/s.

10. A hydraulic fluid composition according to any one of Claims 1 to 8, characterised in that it has an equilibrium reflux boiling point (E.R.B.P.) equal to or greater than 300°C and a viscosity measured at - 40°C, equal to or less than 1400 mm2/s.

Ansprüche

1. Eine hydraulische Flüssigkeitszusammensetzung auf Basis von zumindest einem Glykolether oder auf zumindest einem Borsäureester eines Glykolethers oder einer Mischunq der zwei, dadurch gekennzeichnet, daß sie, als Additiv, zumindest ein Ether-Amin mit einem Molekulargewicht zwischen 120 und 300 enthält und daß sie die nachfolgende Formel:

aufweist, in welcher R₃ ein linearer oder verzweigter Rest ist, mit zumindest einer Ether-funktionellen Gruppe und keiner Alkohol-funktionellen Gruppe, R ein Methylrest oder ein Wasserstoffatom ist, p eine ganze Zahl mit einem Wert von 1 bis 3 ist und q eine ganze Zahl mit einem Wert von 0 bis 2 ist.

2. Eine hydraulische Flüssigkeitszusammensetzung nach Anspruch 1, dadurch gekennzeichnet, daß R₃ eine Gruppe mit der Formel R₁-O-R₂- ist, in welcher R₁ ein linearer oder verzweigter Alkylrest ist und R₂ einen linearen oder verzweigten Alkylenrest bedeutet.

3. Eine hydraulische Flüssigkeitszusammensetzunq nach Anspruch 2, dadurch gekennzeichnet, daß R₁ ein linearer oder verzweigter Alkylrest mit 1 bis 5 Kohlenstoffatomen ist und R₂ einen linearen oder verzweigten Alkylenrest mit 2 bis 8 Kohlenstoffatomen bedeutet.

4. Eine hydraulische Flüssigkeitszusammensetzunq nach irgendeinem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß das Ether-Amin ein Molekularqewicht zwischen 150 und 250 hat.

5. Eine hydraulische Flüssigkeitszusammensetzung nach irgendeinem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß sie, nach Gewicht, von 0,5 bis 5 % des Ether-Amins enthält.

6. Eine hydraulische Flüssigkeitszusammensetzung nach irgendeinem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß sie eine Viskosität, gemessen bei 40°C, von weniger als 10 mm²/s hat.

7. Eine hydraulische Flüssigkeitszusammensetzung, enthaltend nach Gewicht:

a) Von 60 bis 95 % Borsäureester des Monomethylethers von Triethylenqlykol,

b) von 0 bis 15 % Monomethylether von Triethylenglykol,

c) von 0 bis 15 % Monobutylether von Triethylenglykol,

d) von 0,5 bis 5 % eines Ether-Amins und mit einem Molekulargewicht zwischen 120 und 300 und der folgenden Formel:

in welcher R₃ ein linearer oder verzweigter Rest mit zumindest einer Ether-funktionellen Gruppe und keiner Alkohol-funktionellen Gruppe ist, R einen Methylrest oder ein Wasserstoffatom bedeutet, p eine ganze Zahl mit einem Wert von 1 bis 3 ist und q eine ganze Zahl mit einem Wert von 0 bis 2 bedeutet.

8. Eine hydraulische Flüssigkeitszusammensetzung nach Anspruch 7, dadurch gekennzeichnet, daß R₃ eine Gruppe mit der Formel R₁-O-R₂- bedeutet, in welcher R₁ ein linearer oder verzweigter Alkylrest mit von 1 bis 5 Kohlenstoffatomen ist und R₂ einen linearen oder verzweigten Alkylenrest mit von 2 bis 8 Kohlenstoffatomen bedeutet.

9. Eine hydraulische Flüssigkeitszusammensetzunq nach irgendeinem der Ansprüche 1 bis 8, dadurch gekennzeichnet, daß sie einen Gleichgewichtsrückfluß-Siedepunkt (E.R.B.P.) von gleich oder größer von 270°C hat und eine Viskosität, gemessen bei -40°C, von gleich oder weniger als 1100 mm²/s.

10. Eine hydraulische Flüssigkeitszusammensetzunq nach irgendeinem der Ansprüche 1 bis 8, dadurch gekennzeichnet, daß sie einen Gleichgewichtsrückfluß-Siedepunkt (E.R.B.P.) von gleich oder größer als 300°C hat und eine Viskosität, gemessen bei -40°C, von gleich oder weniger als 1400 mm²/s.

Revendications

1. Composition de fluide hydraulique à base d'au moins un éther de glycol ou d'au moins un ester borate d'un éther de glycol, ou encore d'un mélange des deux, caractérisée en ce qu'elle contient, à titre d'additif, au moins une éther-amine ayant une masse moléculaire de 120 à 300 et ayant la formule suivante :

dans laquelle R₃ est un radical linéaire ou ramifié ayant au moins un groupe fonctionnel éther et pas de groupe fonctionnel alcool, R est un radical méthyle ou un atome d'hydrogène, p est un entier de 1 à 3 et q est un entier de 0 à 2.

2. Composition de fluide hydraulique selon la revendication 1, caractérisée en ce que R₃ est un groupe de formule R₁-O-R₂- dans laquelle R₁ est un radical alkyle linéaire ou ramifié et R₂ est un radical alkylène linéaire ou ramifié.

3. Composition de fluide hydraulique selon la revendication 2, caractérisée en ce que R₁ est un radical alkyle linéaire ou ramifié ayant de 1 à 5 atomes de carbone et R₂ est un radical alkylène linéaire ou ramifié ayant de 2 à 8 atomes de carbone.

4. Composition de fluide hydraulique selon l'une des revendications 1 à 3, caractérisée en ce que l'éther-amine a une masse moléculaire de 150 à 250.

5. Composition de fluide hydraulique selon l'une des revendications 1 à 4, caractérisée en ce qu'elle contient, en poids, de 0,5 à 5 % de l'éther-amine.

6. Composition de fluide hydraulique selon l'une des revendications 1 à 5, caractérisée en ce qu'elle a une viscosité, mesurée à 40°C, inférieure à 10 mm²/s.

7. Composition de fluide hydraulique contenant, en poids :

a) de 60 à 95 % d'ester borate de l'éther monométhylique de triéthylèneglycol,

b) de 1 à 15 % d'éther monométhylique de triéthylèneglycol,

c) de 0 à 15 % d'éther monobutylique de triéthylèneglycol et

d) de 0,5 à 5 % d'une éther-amine ayant une masse moléculaire de 120 à 300 et ayant la formule suivante :

dans laquelle R₃ est un radical linéaire ou ramifié ayant au moins un groupe fonctionnel éther et pas de groupe fonctionnel alcool, R est un radical méthyle ou un atome d'hydrogène, p est un entier de 1 à 3 et q est un entier de 0 à 2.

8. Composition de fluide hydraulique selon la revendication 7, caractérisée en ce que R₃ est un groupe de formule R₁-O-R₂- dans laquelle R₁ est un radical alkyle linéaire ou ramifié ayant de 1 à 5 atomes de carbone et R₂ est un radical alkylène linéaire ou ramifié ayant de 2 à 8 atomes de carbone.

9. Composition de fluide hydraulique selon l'une des revendications 1 à 8, caractérisée en ce qu'elle a un point d'ébullition au reflux à l'équilibre (E.R.B.P.) égal ou supérieur à 270°C et une viscosité, mesurée à-40°C, égale ou inférieure à 1100 mm²/s.

10. Composition de fluide hydraulique selon l'une des revendications 1 à 8, caractérisée en ce qu'elle a un point d'ébullition au reflux à l'équilibre (E.R.B.P.) égal ou supérieur à 300°C et une viscosité, mesurée à -40°C, égale ou inférieure à 1400 mm²/s.