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EP-3947611-B1 - A MIDDLE-PRESSURE POLYMERIZATION PROCESS FOR LIQUID ETHYLENE COPOLYMERS

EP3947611B1EP 3947611 B1EP3947611 B1EP 3947611B1EP-3947611-B1

Inventors

  • GARCIA CASTRO, IVETTE
  • GRABARSE, WOLFGANG
  • STRITTMATTER, JAN
  • KOSCHABEK, RENE
  • RUPANER, ROBERT

Dates

Publication Date
20260506
Application Date
20200323

Claims (12)

  1. A middle-pressure polymerization process for the preparation of a liquid ethylene copolymer which comprises in polymerized form - 20 to 60 wt% of ethylene; and - at least 30 wt% of an acrylate, which is selected from C 1 -C 22 alkyl (meth)acrylate, where a monomer mix comprising the ethylene and the acrylate is polymerized at a pressure of 50 to 400 bar and in the presence of at least 2 wt% of a chain transfer agent, and where the percentages of all monomers in the monomer mix sum up to 100 wt%, and where the percentage of the chain transfer agent is based on the sum of the amounts of monomers and the chain transfer agent.
  2. The polymerization process according to claim 1, where the chain transfer agents are saturated or unsaturated hydrocarbons, aliphatic ketones, aliphatic aldehydes, or hydrogen, or mixtures thereof.
  3. The polymerization process according to claim 1 or 2, where the monomer feed is polymerized in the presence of 4 to 18 wt%, preferably 6 to 15 wt% of the chain transfer agent.
  4. The polymerization process according to any of claims 1 to 3, where the polymerization process is a fed-batch process in which a reactor is partly filled with the ethylene and a solvent, followed by feeding of the acrylate, the chain transfer agent, and an initiator.
  5. The polymerization process according to any of claims 1 to 4, where the polymerization process is carried out at a pressure in the range from 70 to 300 bar, and preferably 80 to 200 bar.
  6. The polymerization process according to any of claims 1 to 5, where the monomer mix is polymerized in a polymerization solvent.
  7. The polymerization process according to any of claims 1 to 6, where the ethylene copolymer comprises in polymerized form at least 40 wt%, and in particular at least 50 wt% of the acrylate.
  8. The polymerization process according to any of claims 1 to 7, where the acrylate comprises - a polar acrylate selected from C 1 -C 5 alkyl (meth)acrylate, and - an unpolar acrylate selected from C 6 -C 22 alkyl (meth)acrylate.
  9. The polymerization process according to claim 8, where the polar acrylate is methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, or n-butyl (meth)acrylate.
  10. The polymerization process according to claim 8, where the unpolar acrylate is selected from C 8 -C 18 alkyl (meth)acrylate, in particular from C 8 -C 12 alkyl (meth)acrylate.
  11. The polymerization process according to claim 8, where the unpolar acrylate is selected from (meth)acrylates of n-octyl, isooctyl, 2-ethylhexyl, n-nonyl, 2-propylheptyl, n-decyl, un-decyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, 2-butyloctyl, 2-pentylnonyl, 2-hexyldecyl, isohexyl, isoheptyl, isooctyl, isononyl, isodecyl, isoundecyl, isododecyl, isotridecyl, isotetradecyl, isopentadecyl, isohexadecyl, isoheptadecyl, isooctadecyl and mixtures thereof.
  12. The polymerization process according to claim 8, where the ethylene copolymer comprises in polymerized form - 25 to 55 wt% of ethylene, - at least 20 wt% of the polar acrylate which is selected from C 1 -C 4 alkyl (meth)acrylate, and - at least 15 wt% of the unpolar acrylate which is selected from C 6 -C 22 alkyl (meth)acrylate.

Description

The present invention relates to a middle-pressure polymerization process for the preparation of a liquid ethylene copolymer which comprises in polymerized form 20 to 60 wt% of ethylene; and at least 30 wt% of an acrylate, which is selected from C1-C22 alkyl (meth)acrylate, where a monomer mix comprising the ethylene and the acrylate is polymerized at a pressure of 50 to 400 bar and in the presence of at least 2 wt% of a chain transfer agent, and where the percentages of all monomers in the monomer mix sum up to 100 wt%, and where the percentage of the chain transfer agent is based on the sum of the amounts of monomers and the chain tranfer agent. Combinations of preferred embodiments with other preferred embodiments are within the scope of the present invention. Object was to find a polymerization process for the preparation of ethylene copolymers for lubricants, which should overcome the drawbacks of the prior art. For example the process should be stable, well controlled, reliable, scalable, or allow the production of the desired ethylene copolymer. The process should have a high space time yield, or a high acrylate content in the ethylene copolymer should be achievable. The process should avoid high pressure conditions which require special equipment and safety precautions. The process should allow the use of solvents and it should allow the use of various monomers. The process can be made semi-batch, so the polymerization can progess and the product is free of remaining monomers. Preferably, several of thiese objects should be achieved. Further objects were to find an ethylene copolymer obtainable by the polymerization process or to find a lubricant comprising the liquid ethylene copolymer which should overcome the drawbacks of the prior art. For example the ethylene copolymers or the lubricant comprising the ethylene copolymers should be liquid, should have a low pour point, a good miscibility with apolar base stocks, a good miscibility with polar base stocks, a good oxidation stability, a high viscosity index, a low friction coefficient, a low volatility, a high chemical stability, a high shear stability, a viscosity index, a low sludge, a high cleanliness, a good thickening efficiency, a high hydrolytic stability, or good cold flow properties. Preferably, the ethylene copolymer or the lubricant comprising the ethylene copolymers should provide a combination of several of such advantages. The object was solved by a middle-pressure polymerization process for the preparation of a liquid ethylene copolymer which comprises in polymerized form 20 to 60 wt% of ethylene; andat least 30 wt% of an acrylate, which is selected from C1-C22 alkyl (meth)acrylate, where a monomer mix comprising the ethylene and the acrylate is polymerized at a pressure of 50 to 400 bar and in the presence of at least 2 wt% of a chain transfer agent, and where the percentages of all monomers in the monomer mix sum up to 100 wt%, and where the percentage of the chain transfer agent is based on the sum of the amounts of monomers and the chain tranfer agent. The polymerization process may be a fed-batch process. Preferably, the polymerization process is a fed-batch process in which a reactor is partly filled with the ethylene and a solvent, followed by feeding of the acrylate, the chain transfer agent, and an initiator. The polymerization process may continue for at least 30 min, preferably at least 1 h, and in particular at least 2 h. The polymerization process may take 1 to 10 h, preferably 2-5 h. The polymerization process may be carried out in stirred fed-batch autoclaves, hereinafter also referred to as semi-batch autoclaves. The polymerization process may be carried out at a pressure in the range from 50 to 400 bar, preferably from 70 to 300 bar, and particularly 80 to 200 bar. In another form the polymerization process may be carried out at a pressure of at least 20, 30, 40, 50, 60, 70, 80, or 90 bar. In another form the polymerization process may be carried out at a pressure of up to 120, 140, 160, 180, 200, 220, 240, 260, 280 or 300 bar. Conditions of this type will hereinafter also be referred to as middle-pressure. The pressure can change during the polymerization. The polymerization process may be carried out at a reaction temperature in the range of 50 to 200 °C, preferably 70 to 140 °C, and in particular 80 to 120 °C. The monomer mix may be polymerized in a polymerization solvent, such as in one or more hydrocarbons or one or more ketone(s) which are liquid at room temperature or mixtures of hydrocarbons (e.g. olefins or aromatic hydrocarbons such as toluene, ethylbenzene, ortho-xylene, meta-xylene and para-xylene, also cycloaliphatic hydrocarbons such as cyclohexane and aliphatic C6-C16-hydrocarbons, either branched or unbranched, for example n-heptane, n-octane, isooctane, n-decane, n-dodecane and in particular isododecane), ketones (e.g. acetone, methyl isobutyl ketone, ethyl methyl ketone). Preferred polymerization so