KR0134774B1 - Method for use of the same and lubricant composition component and organophosphate ester - Google Patents

Abstract

Use as lubricants, especially for traction drives, of organophosphate esters of the general formula I:- (R<1>O)2- @-(OR<2>) I wherein each group R<1> individually represents a saturated alicyclic group, preferably cyclohexyl, optionally substituted by one or more alkyl, especially methyl groups, and R<2> represents R<1> or an alkyl or aryl group.

Description

Lubricant compositions containing organic phosphate esters and methods of use thereof as lubricants

The process of the invention relates to the use of certain phosphate ester compounds as lubricants, in particular to their use in traction drives.

These lubricants are of particular value in traction drives and can therefore be used in a variety of engineering applications. Traction is broadly defined as the cohesive friction of the fuselage on the surface on which the fuselage is moving. Traction drive is a device in which torque is transmitted from an input element to an output element therein, typically through linear or point contact with a rolling action by traction between the contact elements. The traction elements usually appear to be in contact, but in fact it is generally believed that a fluid film exists between them. Nearly all traction drives require fluids to remove heat, prevent wear at the contact surfaces, and to slip the bearings and other moving parts associated with the drive. Instead of rolling contact of metal with metal, a fluid film is introduced into the contact zone and sandwiched between the metal elements. The nature of these fluids greatly depends on their limits in performance and ability to operate. Most traction drives are preferably pressurized to operate with traction fluids having a traction coefficient of at least about 0.06, a viscosity of about 4 to 20,000 mPa · s and a good thermal and oxidative stability at temperatures between about 40 ° C. and −20 ° C. The fluid should also be noncorrosive to conventional constituent materials and have good load-bearing and low wear properties.

Mineral base oils are a rather unsatisfactory lubricant for traction dryers because they generally have a low coefficient of traction (friction), which means that the maximum tangential force that can be imparted by the friction wheel for any given load applied to the gear is low. Means that.

It has now been found that certain organic phosphate esters constitute predominant lubricant and traction fluids. The present invention therefore provides a process for the use of organic phosphate esters having the general formula (1) as lubricant, in particular traction fluids:

Wherein R ¹ and R ² are each selected from 2-methylcyclohexyl and 3-methylcyclohexyl groups.

Organic phosphate esters are known compounds and can therefore be prepared by known methods such as the reaction of a suitable alcohol with phosphoryl chloride in the presence of a base such as pyridine or triethylamine and suitably a solvent.

It has been found that the viscosity properties of these ester compounds are very suitable for use in friction wheel gears (traction drives), for example, where they can be mixed with conventional grease midpoints. Such midpoints may be various materials commonly used to concentrate mineral oils to lubricating viscosity, including organic and inorganic compositions such as metallic soaps, synthetic polymers, organosiloxanes, clays, bentonite and colloidal silica. Viscosity properties of the compound for use in the traction drive are suitably such that the compound is operated at -30 to 150 ° C.

These compounds can be used in lubricants in various industrial applications. Since the ester compounds show excellent lubrication performance in traction drives, the present invention provides in particular the use of these ester compounds as traction fluids and a method of operating traction drives in which such esters form traction fluids.

The ester compounds of the present invention can be used as lubricants themselves. They can be mixed with other lubricants, such as mineral or synthetic oils, and various additives such as VI-enhancers, pour point depressants, dispersants, detergents, antioxidants and the like can be added. Since the presence of the polymer can usefully increase the traction coefficient of the fluid blend, the mixtures particularly relevant for traction fluid applications are mixtures with polyolefins, in particular poly-alpha-olefins, especially polyisobutylene. The molecular weight of such polyolefin blend components ranges from 500 to 10,000, which is a particular example of a suitable polyisobutylene which is conveniently Hivis, and the proportion of polyolefins can vary from 0 to 70% by weight.

The following examples, together with their friction and other physical properties, illustrate the preparation of compounds (III and IV) and comparative compounds (I, II and IV) used in the present invention.

Example 1

Tricyclo hexyl phosphate

A solution of cyclohexanol (751.2 g, 7.5 mole) and pyridine (595.0 g, 7.5 mole) in dichloromethane (3.5 liters) is stirred under a dry nitrogen atmosphere and phosphoryl chloride is maintained while maintaining the temperature of the reaction mixture at 15 to 25 ° C. (382.5 g, 2.5 moles) is added dropwise for 1-2 hours. After the addition is complete, stirring is continued for 18 hours at ambient temperature, and then the resulting mixture is filtered. The organic solution was washed with water (3 x 5 liters) and dried (phase MgSO ₄ ), then the solvent was evaporated under vacuum at 30 ° C. to give a pale yellow viscous oil (730.3 g) which slowly solidified upon standing. Get The crude oil is dissolved with stirring in diethyl ether (750 ml) and stirred in a dry ice / acetone cooling bath to cool to -40 to -50 ° C. The precipitate is filtered and dried under vacuum at 25 ° C. to give tri (cyclohexyl) phosphate (520.0 g) as an off-white solid having a melting point of 48 to 50 ° C.

Example 2

Tri (methylcyclohexyl) phosphate

A solution of methylcyclohexanol (technical grade containing a mixture of isomers; 2.08 kg, 18.2 moles) and pyridine (1.44 kg, 18.2 moles) in dichloromethane (10 liters) is stirred under a dry nitrogen atmosphere and the temperature of the reaction mixture is Phosphoryl chloride (930.2 g, 6.07 mol) is added dropwise while maintaining at 15 to 25 ° C. After addition, stirring was continued for 18 h at ambient temperature, after which the resulting mixture was filtered, washed with water (4 x 6 liters), dried (on MgSO ₄ ) and the solvent under vacuum at 30 ° C. By evaporation, the crude product is obtained as a viscous oil. The crude oil was left overnight at room temperature and then filtered, and the other reactions were removed by evaporation of unreacted methylcyclohexanol and other volatile impurities by evaporation on a KDL-4 thin film evaporator (under 85 ° C. and 0.8 mm Hg (107 pa)). The product is obtained as a clear viscous oil (1.75 kg) containing a mixture of isomers.

[Examples 3 to 5]

Except for using 2-methylcyclohexanol, 3-methylcyclohexanol and 4-methylcyclohexanol (in each case a mixture of cis-and-trans-isomers) instead of technical grade methylcyclohexanol The following method is manufactured using the method of Example 2.

III-tri- (2-methylcyclohexyl) phosphate (oil)

IV-tri- (3-methylcyclohexyl) phosphate (oil)

V-tri- (4-methylcyclohexyl) phosphate (oil)

Example 6

Friction Coefficient Measurement

Friction measurements are all performed on a two-disk machine. For tangential contact with each other, they are fixed to hardened steel discs at the ends of the two shafts. To depress the disk, a radial force is applied with a load of 0 to 200 kgf. Each disk is operated by an electric motor. The rotational speed of the two discs is so different that there is slip.

Between the shaft carrying the lower test specimen and the electric motor, a measuring device representing the transmitted frictional torque is fixed. The measuring device is a gear dynamometer having electrons that swing to its vertically balanced position when the force is transmitted, the sinusoidal angle of the inclination measures the torque. Torque measurements are precalibrated through the design and scale of the machine. The coefficient of friction is defined as the torque divided by the measured torque multiplied by the radial force multiplied by the radius of the lower disk.

All of the disks used have a diameter of 50.0 mm, the upper disk is 3 mm wide and the lower disk is 10 mm wide. The top axis speed is 606 rpm and the average tangential (or planar) speed is 1.48 ms ⁻¹ . Slip was 9.1%.

All experiments were conducted at ambient temperature (21 ° C. ± 2 ° C.). Friction readings are made at loads with Hertzian pressures of 0.69, 0.97, 1.19 and 1.38 Gpa.

The coefficient of friction of these compounds is shown in Table V1 below. For the compound of Example 1, wherein m.pt is from 48 to 50 ° C., these coefficients were measured on the supercooled fluid phase at 21 (± 2) ° C.

Dynamic viscosities of these compounds are also included in Table V1 below.

Although the friction coefficients of these compounds are all excellent, the friction coefficients of Examples 3 and 4 appear to be remarkably excellent.

Claims (4)

Lubricant composition containing, as a main component, an organic phosphate ester having Formula 1

Wherein R ¹ and R ² are each selected from 2-methylcyclohexyl and 3-methylcyclohexyl groups. The lubricant composition of claim 1 wherein the organic phosphate ester of formula 1 is tri- (2-methylcyclohexyl) phosphate or tri- (3-methylcyclohexyl) phosphate. A traction fluid comprising the organic phosphate ester as defined in claim 1 or the lubricant composition as claimed in claim 1. A method of operating a traction drive, wherein the traction fluid is an organic phosphate as defined in claim 1 or 2 or a lubricant composition as claimed in claim 1.