CS240817B1 - Silencer Oil - Google Patents

Abstract

Silencer oil with excellent thermo-oxidation stability, high viscosity index and low sulfur content, produced either from the high pressure hydrogenate of the vacuum distillate of alkane oil, dewaxed to a pour point - 18 ° C or lower, with defined chemical composition, or a mixture of such VT-hydrogenate and viscosity modifier (VI) with high shear stability. The necessary utility properties are achieved by the addition of a decant, anti-wear additive, rust inhibitor and anti-foam additive.

Description

The invention relates to a shock absorber oil made from high-pressure hydrogenate of an alkane petroleum distillate, which, after sufficiently deep dewaxing and contact refining, has a high viscosity index and a defined chemical composition, which ensure its excellent thermo-oxidative stability with satisfactory fluidity at low temperatures. Such a shock absorber oil is also suitable as a filling for hydrostatic systems requiring oil with a low viscosity.

The damping force against the mutual oscillatory movement of the unsprung and sprung mass is developed by throttling the oil flow caused by the movement of the piston in the shock absorber cylinder. Oils with a low viscosity in the range of 20-100 mm.s ^x at 20°C are used for shock absorber filling.

Depending on the design of the shock absorber, an oil with a defined narrow viscosity range must be selected. The oil must have a sufficiently high viscosity index and a sufficiently low pour point, or paraffin precipitation point, to have both the necessary minimum viscosity at higher operating temperatures, which can reach up to 70°C due to internal friction, and satisfactory fluidity at low operating temperatures given by ambient temperatures. Thermal-oxidative stability is necessary to achieve a long service life of the oil. For this reason, shock absorber oils may also contain antioxidant additives, preferably those that also have anti-wear and anti-corrosion properties, such as zinc dialkyldithio phosphates with alkyls up to C _g , zinc dialkyldithiocarbamates, derivatives. 2,5-dimercapto-1,3,4-thiodiazoles, etc.

Since it is impossible to prevent moist air from entering the oil filling of the shock absorber, it is advantageous if the oil also contains a rust inhibitor, e.g. of the type of oil-soluble petroleum and synthetic alkylarylsulfonates of sodium, ammonium, calcium, barium, lead, magnesium and zinc, ethylenediaminesulfonates, alkenylmaleic anhydride, low molecular weight succinimides, alkylthioacetic acid derivatives, N-acyl derivatives of sarcosine, substituted imidazolines,

- 2,240,817 amine salts of mixed alkyl phosphates, non-ionic esters of fatty acids and hexavalent alcohols, fatty acid amides, etc.

For the same reasons, damper oil commonly contains an additive to prevent foam formation (most often silicone oil, especially of the methylphenylsiloxane type) during significant kneading and rapid movement and changes in oil pressure with adsorbed air and moisture.

To achieve the required viscosity and increase the viscosity index, a polymer viscosity modifier (VI) can be added, either a polymethacrylate with high shear stability with _Mw 100,000 - 200 QOOj or an olefin polymer (e.g. polybutylene or atactic polypropylene with Mw 25,000 - 40,000), or an olefin copolymer (e.g. ethylene-propylene or styrene-diene copolymer with _Mw 70,000 - 100,000).

To achieve a sufficiently low pour point, a depressant is added to the shock absorber oil, most often of the polyalkyl methacrylate type or a condensation product of chlorinated paraffins with β naphthalene (Paraflow), but also of the polyacrylate and polyvinyl acetate type.

Shock absorber oil of this composition is also suitable as a filling for hydrostatic systems that require oil with a low viscosity.

Shock absorber oils are commonly made from cyclanic oil raffinates, which naturally have low pour points and good fluidity at low temperatures, but their disadvantages are lower viscosity indices and poorer thermo-oxidative stability.

The essence of the invention is a shock absorber oil with excellent thermo-oxidative stability, with a high viscosity index and with a low sulfur content _f ktcřty is formed by contact-refined high-pressure hydrogenate from vacuum distillate of paraffinic crude oil, dewaxed to a freezing point below -1g°C, having a viscosity index of 2 -1 min. 80 and a kinematic viscosity of 2.0 to 5.0 mm .s /100°C with an aromatics content of 2.0 to 8.0% wt, cyclanes C _N 25 to 42% lim (determined by V _K - n - d analysis), sulfur max. 0.1% wt, a small amount of depressant and antifoaming agent. To achieve a comprehensive

- 3 ~

240 817 satisfactory utility properties can be refined with an oxidation inhibitor, preferably of a type that also has anti-corrosion and anti-wear effects, a rust inhibitor and a viscosity modifier (VI) with high shear stability. The viscosity of the dewaxed high-pressure hydrogenate must be selected so that after the addition of a depressant or viscosity modifiers (VI) the resulting oil has the desired viscosity at both high and low temperatures.

Example 1

A damper oil was prepared consisting of 99.798% wt. high-pressure hydrogenate of vacuum oil distillate of romaškina crude oil, dewaxed to a freezing point of -22°C and contact-refined, which had 5.8% wt., 37.6% gra, Cp 56.6% wt., sulfur content 0.06% wt., 0.2% wt. of a polymethacrylate-type depressant (Plexol 102) and 0.002% wt. of silicone oil as an antifoam additive (Lukooil M 200).

The obtained oil had the following quality parameters:

2-1

Kinematic viscosity, mm.s at 100°C 3.669

50°C 40°C 20°C 12.32 18.93 42.00 Dynamic viscosity (Brookfield), mPa.s at -10°C 600 -2Q°C 850 -30°C 4000 Viscosity index 91 Flash point (OK), °C 172 Cloud point (paraffin precipitation), °C -17 Freezing point, °C -52 Foaming capacity, ml at 24°C 50 93°C 40 24°C after 93°C 40 Foam stability, ml 0/0/0

- 4,240,817

0.2

Oxidation stability (100°C/4h/5 1 air/h)

- acidity number, mg KOH/g - sediment content, % wt

Asphaltenes, % wt

Example 2

A shock absorber oil was prepared as in Example 1, which was additionally refined with 0.7 wt. % zinc dialkyldithiophosphate with i-C^ and i-Oθ alkyls (Multadit OB) and 0.15 wt. % calcium alkylarylsulfonate (Nasul BSN).

The obtained oil had the same quality parameters as the oil in Example 1 and also the following properties and test results:

Demulsification characteristic (oil - water - emulsion), ml after 60 min. 40-37-3

Corrosion on metal3 (3h at 100°C) negative

The protective ability against rust is satisfactory.

Test in a 4-ball machine:

VÚO 22.3

CCP, CP 126/141

Vickers test, wear in mg:

stator 56 lamellas 6

Example 3

A damper oil was prepared consisting of 97.798 wt% dewaxed high-pressure hydrogenate, defined in Example 1, 2 wt% polyisobutylene (Oloa 3198), 0.2 wt% depressant (Plexol 102) and 0.002 wt% antifoam additive (Lukooil M 200).

The obtained oil had the following quality parameters:

Kinematic viscosity, at 100°C 5.321

Dynamic viscosity (Brookfield), mPa.s at -30°C 4300

Viscosity index 98

Flash point (OK), °C 174

Cloud side, °C -17

Freezing point, °C -52

Foaming capacity, ml at 24°C 50 25 25 93 C 24°C after 93°C Foam stability, ml 0/0/0 Oxidation stability - acid number, mg KOH/g 0.15

- sediment content, % wt 0

Asphaltenes, % wt 0

When tested in a Bosch injector (according to DIN 51 382), there was no decrease in oil viscosity after 30 cycles.

Claims (3)

SUBJECT OF THE INVENTION 1. Silencer oil impels ^{240 817} 2e consists of contact refined high pressure hydrogenated paraffinic petroleum distillate vacuum, dewaxed to a freezing point of -18 ° C or lower, with a kinematic viscosity at 100 ° C of 2.0 to 5.0 mm 2 · s 4 and a viscosity index of min. 80, having an aromatics content of 2.0 to 8.0% by weight, cyclanes Cj of 25 to 42% by weight (as determined by V-nd analysis) and a sulfur content of max. 0.1% by weight, from 0.05 to 3.0% by weight wt% of a polymethacrylate-type depressant and / or a polyalkylnaphthalene-type depressant and from 0.001 to 0.01 wt% of a silicone oil-based antifoam agent. 2. A buffer oil according to claim 1, further comprising from 0.2 to 1.0% by weight of an anti-abrasion additive, preferably zinc dialkyldithiophosphate with alkyls up to C8, which also has antioxidant and anticorrosive properties, and from 0.05 to 0%. 5 wt.% Rust inhibitor, preferably calcium alkylarylsulfonate. The buffer oil according to claim 1 or 2, characterized in that it further comprises 0.5 to 10% by weight of a high shear stability polymeric viscosity modifier (VI), preferably polybutene or atactic polypropylene with an M 20 000 to 40 000. w Printed by Moravian printing works, center. 11 100, tr.Lidovy milici 3, Olomouc Price: 2,40 Kčs