HYDRAULIC COMPOSITION FOR EXTREME COLD

Abstract

The invention relates to the field of lubricants and provides a lubricating composition comprising at least one base oil, the kinematic viscosity of which measured at 40 C. does not exceed 10 mm.sup.2/s and the pour point of which does not exceed 50 C., and at least one thickener, said lubricating composition having a pour point not exceeding 55 C.

Claims

1. Lubricant composition comprising: at least one base oil having kinematic viscosity measured at 40 C. less than or equal to 10 mm.sup.2/s and having a pour point lower than or equal to 50 C.; and at least one thickener selected from among: polyalkylene glycols (PAGs) comprising at least 50 weight % of butylene oxide repeat units and having kinematic viscosity measured at 100 C. according to standard ASTM D445 (2015) greater than or equal to 50 mm.sup.2/s, kinematic viscosity measured at 40 C. according to standard ASTM D445 (2015) greater than or equal to 500 mm.sup.2/s, and a viscosity index measured according to standard ASTM D2270 (2012) higher than or equal to 160; linear or branched, alkoxylated polyethylene glycols; and mixtures thereof; said lubricant composition having a pour point lower than or equal to 55 C.

2. The composition according to claim 1, comprising at least a viscosity index improver.

3. The composition according to claim 1 wherein the base oil is selected from among Group III, IV or V oils, preferably from among Group IV and/or V oils.

4. The composition according to claim 1, wherein the base oil comprises more than 90 weight % of iso-paraffins, preferably more than 95% and further preferably more than 98%, and less than 300 ppm, preferably less than 100 ppm, more preferably less than 50 ppm, further preferably less than 20 ppm of aromatics.

5. The composition according to claim 3, wherein the iso-paraffin/n-paraffin weight ratio characterizing the base oil is higher than or equal to 12:1, preferably higher than or equal to 15:1, and advantageously higher than or equal to 20:1.

6. The composition according to claim 1, wherein the base oil has kinematic viscosity measured at 40 C. of between 1 and 10 mm.sup.2/s, preferably between 2 and 10 mm.sup.2/s, more preferably between 2 and 8 mm.sup.2/s and further preferably between 2 and 4 mm.sup.2/s.

7. The composition according to claim 1, comprising from 50 to 85 weight % of base oil relative to the total weight of the composition, preferably 55 to 80%, more preferably 60 to 75%.

8. The composition according to claim 1, wherein the PAGs comprise at least 80 weight % of butylene oxide repeat units.

9. The composition according to claim 1, wherein the alkoxylated polyethylene glycols are of general formula (I) ##STR00003## where: m is an integer of between 0 and 30; m is an integer between 0 and 30; (m+m) is an integer between 1 and 60; k is an integer between 2 and 50; and R.sub.1 designates a linear or branched, non-substituted alkyl radical having 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27 or 28 carbon atoms; whereby the concatenations denoted k, m and m are distributed to form a block polymeric structure.

10. The composition according to claim 1, wherein the content of active thickening material is between 5 and 50 weight % relative to the total weight of the lubricant composition, preferably from 10 to 45%.

11. The composition according to claim 1, comprising from 5 to 20 weight % of active viscosity improving material relative to the total weight of the composition, preferably 5 to 15%.

12. Use of a lubricant composition according to claim 1, as industrial lubricant composition or hydraulic fluid.

13. Method for lubricating parts of industrial machinery wherein the parts of the machinery to be lubricated is put into contact with the composition of claim 1.

14. Method for lubricating parts of industrial machinery use at temperatures lower than 40 C. wherein the parts of the machinery to be lubricated is put into contact with the composition of claim 1.

Description

EXAMPLE 1

Preparation of Lubricant Compositions CL1, CL2 and CL3 of the Invention

[0102] The different components of the lubricant compositions of the invention are mixed together according to the product types and amounts given in Table 1.

TABLE-US-00002 TABLE 1 Lubricant Lubricant Lubricant com- com- com- position position position CL1 of the CL2 of the CL3 of the invention invention invention (wt. %) (wt. %) (wt. %) Group V oil: KV40 = 2.49 mm.sup.2/ 51.02 0 48.02 s and pour point = 81 C.) Group IV oil: KV40 = 5.2 mm.sup.2/ 0 62.02 0 s and pour point = 63 C.) (Thickener) PAG, KV100 = 43.00 32.00 41.00 680 mm.sup.2/s .sup.(1) Polyalkylmethacrylate, 5.00 5.00 5.00 KV100 = 1200 mm2/s 0 5.00 Lubricity modifier .sup.(2) 0 Additive package 0.98 0.98 0.98 .sup.(1) PAG, KV100 = 680 mm.sup.2/s commercially available from DOW under the trade nameUCON-OSP 680. .sup.(2) Lubricity modifier being 2-ethylhexyl sebacate. .sup.(3) The additive package is a conventional, commercial additive package particularly comprising a defoamer, anti-corrosion additive, antioxidant additive.

EXAMPLE 2

Measurement of the Characteristics of Lubricant Compositions CL1, CL2 and CL3

[0103] The characteristics of lubricant compositions CL1, CL2 and CL3 (kinematic viscosity, viscosity index and pour point) are given in Table 2.

TABLE-US-00003 TABLE 2 CL1 CL2 CL3 Kinematic viscosity at 40 C. (mm.sup.2/s) 29.7 30.5 30.1 Kinematic viscosity at 100 C. (mm.sup.2/s) 8.53 7.97 8.52 Calculated viscosity index 289 252 284 Pour point ( C.) 60 57 60 Loss of viscosity at 100 C. Less than Less than Less than after 20 h KRL shear 15% 15% 15%

[0104] Kinematic viscosities at 40 C. and 100 C. were measured according to standard ISO 3104 of 15 Jul. 1997.

[0105] The lubricant compositions of the invention have good viscosifying properties in particular at 40 and 100 C.

[0106] The viscosity index was calculated according to standard ISO 2909 of 15 Dec. 2002. The pour point was measured according to standard ISO 3016 of 1 Aug. 1994.

[0107] Loss of viscosity at 100 C. after 20 h KRL shear was measured according to standard DIN 51350-6.

[0108] Loss of viscosity at 100 C. after 20 h KRL shear shows that the lubricant compositions of the invention have very good stability under shear.

[0109] The lubricant compositions of the invention are characterized by a pour point lower than or equal to 57 C., a viscosity index of between 252 et 289 and very low loss of viscosity after KRL shear.

[0110] These characteristics show that the lubricant compositions of the invention can be used as hydraulic fluid in polar climates. In addition, with their excellent shear resistance (KRL test), the lubricant compositions maintain their properties when in use.