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CN-122003488-A - Poly (alkyl (meth) acrylate) polymers as high viscosity base fluids

CN122003488ACN 122003488 ACN122003488 ACN 122003488ACN-122003488-A

Abstract

The present invention relates to polyalkyl (meth) acrylate polymers and to a process for preparing these polymers. The invention also relates to a lubricating oil composition comprising the above polymer, and to the use of the polymer in a lubricating oil composition, preferably in a gear oil composition, a transmission oil composition, a hydraulic oil composition, an engine oil composition, a marine oil composition, an industrial lubricating oil composition or in a grease as a lubricant additive or as a synthetic base fluid.

Inventors

  • S.K. Meyer
  • K. Northfurt
  • K. SCHULER
  • K. Jovich
  • S. Half
  • J. MURRAY
  • D. Jansen

Assignees

  • 赢创运营有限公司

Dates

Publication Date
20260508
Application Date
20241009
Priority Date
20231016

Claims (15)

  1. 1. A poly (meth) acrylic acid alkyl ester polymer obtainable by polymerizing a monomer composition consisting of: a) At least 85% by weight, based on the total weight of the monomer composition, of a) a monomer selected from alkyl methacrylates of formula (I) or mixtures thereof, Wherein R 1 is a linear or branched alkyl radical having 9 or 10 carbon atoms, and wherein 80 to 100% by weight of the radicals R 1 , based on the total weight of the methacrylate monomers a) of the formula (I), are branched, B) 0 to 15 wt%, based on the total weight of the monomer composition, of a monomer b) selected from alkyl methacrylate monomers having a linear or branched alkyl chain of 11 to 30 carbon atoms or mixtures thereof, C) 0 to 3 wt%, based on the total weight of the monomer composition, of a monomer c) selected from alkyl (meth) acrylates having a linear alkyl chain of 1 to 6 carbon atoms, alkyl acrylates having an alkyl chain of 7 to 18 carbon atoms, or mixtures thereof, Wherein more than 80 weight percent of the monomers a), b) and c) in the monomer composition are branched, and Wherein the polyalkyl (meth) acrylate polymer has a weight average molecular weight of 5,000 to 30,000 g/mol according to DIN 55672-1.
  2. 2. The polyalkyl (meth) acrylate polymer according to claim 1, wherein the polyalkyl (meth) acrylate polymer has a kinematic viscosity according to ASTM D445 of 1,000 to 50,000 mm 2 /s at 100 ℃.
  3. 3. The polyalkyl (meth) acrylate polymer according to claim 2, wherein the polyalkyl methacrylate has a kinematic viscosity according to ASTM D445 of 1,000 to 30,000 mm 2 /s at 100 ℃, preferably 1,200 to 20,000 mm 2 /s at 100 ℃ according to ASTM D445, more preferably 1,500 to 10,000 mm 2 /s at 100 ℃ according to ASTM D445.
  4. 4. The polyalkyl (meth) acrylate polymer according to any of the preceding claims, wherein the monomer a) is selected from isononyl methacrylate, 2, 6-dimethyl-4-heptyl methacrylate, 2-propylheptyl methacrylate, isodecyl methacrylate or a mixture thereof.
  5. 5. The polyalkyl (meth) acrylate polymer according to any of the preceding claims, wherein the monomer composition comprises from 85 to 100 wt. -%, preferably from 85 to 99.9 wt. -%, more preferably from 85 to 95 wt. -%, still more preferably from 85 to 94.9 wt. -%, of monomer a), based on the total weight of the monomer composition.
  6. 6. The polyalkyl (meth) acrylate polymer according to any of the preceding claims, wherein the monomer composition comprises 5 to 15 wt. -%, preferably 5 to 14.9 wt. -%, of monomer b), based on the total weight of the monomer composition.
  7. 7. The polyalkyl (meth) acrylate polymer according to any of the preceding claims, wherein the monomer composition comprises 0.1 to 3 wt% of monomer c), based on the total weight of the monomer composition.
  8. 8. The polyalkyl (meth) acrylate polymer according to any one of claims 1 to 3, wherein the total amount of alkyl methacrylate monomers a) in the monomer composition is 100 wt% based on the total weight of the monomer composition.
  9. 9. The polyalkyl (meth) acrylate polymer according to any of the preceding claims, wherein the polyalkyl (meth) acrylate polymer has a weight average molecular weight of 10,000 to 25,000g/mol, preferably 13,000 to 20,000 g/mol according to DIN 55672-1.
  10. 10. The polyalkyl (meth) acrylate polymer according to any of the preceding claims, wherein the polyalkyl (meth) acrylate polymer has a polydispersity index of from 1.0 to 2.5, preferably from 1.5 to 2.2, more preferably from 1.5 to 2.0.
  11. 11. A process for preparing a poly (alkyl (meth) acrylate) polymer according to any one of claims 1 to 10, wherein the process comprises the steps of: i) Providing the monomer composition according to any one of claims 1 and 4 to 8, and Ii) initiating a free radical polymerization in the monomer composition of step i) to obtain the polyalkyl (meth) acrylate polymer.
  12. 12. A lubricating oil composition comprising one or more base oils and at least one polyalkyl (meth) acrylate polymer according to any one of claims 1 to 10.
  13. 13. The lubricating oil composition of claim 12, wherein the base oil is selected from API group I mineral oil, API group II mineral oil, API group III mineral oil, or mixtures thereof.
  14. 14. The lubricating oil composition of claim 12 or 13, wherein the lubricating oil composition comprises 5 to 50 wt.%, more preferably 10 to 40 wt.%, still more preferably 10 to 30 wt.% of the polyalkyl (meth) acrylate polymer, based on the total weight of the lubricating oil composition.
  15. 15. Method of thickening a lubricating oil composition by adding a polyalkyl (meth) acrylate polymer according to any one of claims 1 to 10 as a lubricant additive or synthetic base fluid to the lubricating oil composition, preferably in a gear oil composition, a transmission oil composition, a hydraulic oil composition, an engine oil composition, a marine oil composition, an industrial lubricating oil composition or in a grease.

Description

Poly (alkyl (meth) acrylate) polymers as high viscosity base fluids Technical Field The present invention relates to polyalkyl (meth) acrylate polymers and to a process for preparing these polymers. The invention also relates to a lubricating oil composition comprising the above polymer, and to the use of the polymer in a lubricating oil composition, preferably in a gear oil composition, a transmission oil composition, a hydraulic oil composition, an engine oil composition, a marine oil composition, an industrial lubricating oil composition or in a grease as a lubricant additive or as a synthetic base fluid. Background The present invention relates to the field of lubrication. Lubricants are compositions that reduce friction between surfaces. In addition to allowing freedom of movement between the two surfaces and reducing mechanical wear of the surfaces, the lubricant may inhibit corrosion of the surfaces and/or may inhibit damage to the surfaces due to heat or oxidation. Examples of lubricant compositions include, but are not limited to, engine oils, transmission fluids, gear oils, industrial lubricating oils, greases, and metal working oils. Lubricants typically contain a base fluid and variable amounts of additives. The terms "base oil", "base stock" or "base fluid" are generally used interchangeably. The base fluid is used herein as a generic term. The high viscosity base fluid is used to raise the Viscosity Index (VI) and thicken lubricant formulations with stringent shear stability requirements. A typical application is gear oil, which has very demanding requirements due to the high mechanical stresses and wide temperature range in operation. Various additives may be combined with the base fluid depending on the intended use of the lubricant. Examples of lubricant additives include, but are not limited to, viscosity index improvers, thickeners, pour point depressants, oxidation inhibitors, corrosion inhibitors, dispersants, high pressure additives, defoamers, and metal deactivators. The most common thickener used in mineral oil based industrial gear oils is bright stock. Bright stock is a technically outdated group I base oil refinery product and therefore future supplies are unknown. Replacement with alternative thickeners is difficult because typical polyolefin thickeners such as Polyisobutylene (PIB), olefin Copolymers (OCP) and Polyalphaolefins (PAO) are very nonpolar, which results in compatibility problems (LUBES 'N' GREASES (2015) 4, pages 52-60; LUBES 'N' GREASES (2021) 11, pages 24-29; LUBES 'N' GREASES (2022) 4, pages 35-38). The viscosity of the gloss oil is also limited, so a high ISO viscosity grade such as 680 or 1000 requires a more powerful thickener in combination with the gloss oil. The advantage of using alternative thickeners with higher polarity is that these polar high viscosity base fluids do not require the addition of non-polar low viscosity fluids, such as esters, as compatibilizers for polar lubricant additives. In addition, polar high viscosity fluids generally do not cause problems with coating and sealing compared to polar low viscosity fluids. Such thickeners having a higher polarity are, for example, copolymers of alpha-olefins with maleates (e.g. DE 3223694), copolymers of alpha-olefins with acrylic esters (e.g. DE2243064 or EP 4015604), copolymers of alpha-olefins with methacrylic esters (e.g. EP 0471266) or terpolymers based on the above-mentioned monomers (e.g. WO 2020078770). Alternatively, an oil compatible polyester (e.g. WO0146350 or WO 2022003087), a polyvinyl ether (US 20130165360), a polyacrylate (e.g. EP 4073210) or a polyalkyl (meth) acrylate (PAMA) may be applied. More specifically, the polyalkyl (meth) acrylate base fluid (PAMA base fluid) is primarily used as a thickener with similar performance parameters as the polyalphaolefin base fluid (PAO base fluid) and is designed as a very high performance synthetic or semi-synthetic formulation. PAMA base fluids are commonly used for most demanding applications, such as wind turbine gear oils. Document US9,617,495 discloses polyalkyl (meth) acrylates for use in lubricants with high viscosity index and good antiwear properties, in particular in wind turbine transmissions. To achieve this end use, the polyalkyl (meth) acrylate polymers disclosed in US9,617,495 are prepared using a monomer mixture comprising from 50 to 100 wt% of linear and branched C 6-C15 alkyl (meth) acrylate, wherein the amount of branched alkyl (meth) acrylate is from 5 to 80 wt%, preferably from 10 to 65 wt%, based on the total weight of C 6-C15 alkyl (meth) acrylate. All examples are based on careful balancing of linear and branched monomers to provide a high Viscosity Index (VI) while preventing crystallization at low temperatures. It is described that the transmission lubricant must contain at least 30% by weight of polyalkyl (meth) acrylate, which is a very high dosing amount (TREAT RATE). However, for applications requiring less, the h