Polymerization process for liquid copolymers of ethylene and hydroxyalkyl(meth)acrylate

Abstract

The present invention relates to a continuous high-pressure polymerization process for the preparation of a liquid ethylene copolymer which comprises in polymerized for methylene; and a reactive acrylate which is selected from hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate, where a monomer feed comprising the ethylene and the reactive acrylate is polymerized in the presence of at least 2 wt % of a chain transfer agent. The present invention also relates to the liquid ethylene copolymer, to a coating material comprising the liquid ethylene copolymer and to a use of the liquid ethylene copolymer to produce a coating material.

Claims

1. A continuous high-pressure polymerization process for the preparation of a liquid ethylene copolymer which comprises in polymerized form ethylene; a reactive acrylate which is selected from hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate, and an alkyl (meth)acrylate which is selected from C.sub.1-C.sub.22 alkyl (meth)acrylate; wherein a monomer feed comprising the ethylene and the reactive acrylate is polymerized in the presence of at least 2 wt % of a chain transfer agent.

2. The polymerization process according to claim 1, wherein 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, wherein the chain transfer agents are propionaldehyde, methyl ethyl ketone, or hydrogen, or mixtures thereof.

4. The polymerization process according to claim 1, wherein the monomer feed is polymerized in the presence at least 8 wt % of the chain transfer agent.

5. The polymerization process according to claim 1, wherein the chain transfer agent is a mixture of propionaldehyde and methyl ethyl ketone in a weight ratio of 4:1 to 1:4.

6. The polymerization process according to claim 1, wherein the polymerization process is carried out at a pressure in the range from 1000 to 4000 bar.

7. The polymerization process according to claim 1, wherein the polymerization process is carried out at a pressure in the range from 1200 to 2500 bar.

8. The polymerization process according to claim 1, wherein the polymerization process is carried out at a pressure in the range from 1600 to 2000 bar.

9. The polymerization process according to claim 1, wherein the ethylene copolymer comprises in polymerized form 20 to 60 wt % of the ethylene.

10. The polymerization process according to claim 1, wherein the ethylene copolymer comprises in polymerized form more than 2 wt % of the reactive acrylate.

11. The polymerization process according to claim 1, wherein the ethylene copolymer comprises in polymerized form at least 10 wt % of the alkyl (meth)acrylate.

12. The polymerization process according to claim 1, wherein the alkyl (meth)acrylate is selected from C.sub.1-C.sub.12 alkyl (meth)acrylate.

13. The polymerization process according to claim 1, wherein the ethylene copolymer comprises from 15 to 70 wt % of the alkyl (meth)acrylate.

14. The polymerization process according to claim 1, wherein the ethylene copolymer is free of further monomers beside the ethylene, the reactive acrylate, and the alkyl (meth)acrylate.

15. A liquid ethylene copolymer produced by the process as defined in claim 1.

16. A coating material comprising the liquid ethylene copolymer as defined in claim 15.

17. A continuous high-pressure polymerization process for the preparation of a liquid ethylene copolymer which comprises in polymerized form ethylene; and a reactive acrylate which is selected from hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate, wherein a monomer feed comprising the ethylene and the reactive acrylate is polymerized in the presence of at least 2 wt % of a chain transfer agent and wherein the chain transfer agent is a mixture of propionaldehyde and methyl ethyl ketone in a weight ratio of 4:1 to 1:4.

Description

EXAMPLES

(1) NBA: N-butyl acrylate

(2) MMA: Methyl methacrylate

(3) EHA: 2-Ethylhexyl acrylate, commercially available from BASF SE

(4) HEMA: Hydroxyethyl methacrylate

(5) Preparation of Copolymers

(6) A high-pressure autoclave, of the type described in the literature (M. Buback et al, Chem. Ing. Tech. 1994, 66, 510-513) was used for continuous copolymerization

(7) Ethylene was fed continuously into a first compressor until approx. 250 bar. Separately from this, the amount of HEMA and the alkyl (meth)acrylate (NBA, MMA or EHA) was also compressed continuously to an intermediate pressure of 250 bar and was mixed with the ethylene fed. The ethylene/acrylate mixture was further compressed using a second compressor. The reaction mixture is brought to a 1 liter autoclave with pressure and temperatures given also according to Table 1. The desired temperature is controlled depending on the amount of initiator tert-amyl peroxypivalate in isodecane, which is introduced to the autoclave separately from the monomer feed (about 1000-1500 ml/h).

(8) Separately from this, the amount of chain transfer agent (cf. Table 1 “Regulator Feed”) was first compressed to an intermediate pressure of 250 bar and then fed continuously into the high-pressure autoclave with the aid of a further compressor under the reaction pressure.

(9) The output of the reactions in Table 1 was usually around 5-6 kg/h at a conversion of 30 to 45 wt % (based on ethylene feed). Details of the reaction conditions were summarized in Table 1 and the analytical data of the liquid ethylene copolymers are summarized in Table 2.

(10) TABLE-US-00001 TABLE 1 Preparation of liquid ethylene copolymers (PA: propionaldehyde, MEK: methylethylketone) P T Ethylene Regulator Ex. Monomers [bar] [° C.] Feed [g/h] AcrylateFeed Feed 1 E-HEMA- 1800 200 12010 HEMA: PA: 1200 g/h NBA 560 g/h (6.9 wt %) NBA: MEK: 560 g/h 2990 g/h (3.2 wt %) 2 E-HEMA- 1802 203 12000 HEMA: PA: 1200 g/h NBA 1755 g/h (6.5 wt %) NBA: MEK: 1755 g/h 1770 g/h (9.5 wt %) 3 E-HEMA- 1802 201 12130 HEMA: PA: 1200 g/h NBA 1860 g/h (6.2 wt %) NBA: MEK: 1860/h 2240 g/h (9.6 wt %) 4 E-HEMA- 1800 202 11965 HEMA: PA: 1200 g/h NBA 1000 g/h (6.7 wt %) NBA: MEK: 1000 g/h 2700 g/h (5.6 wt %) 5 E-HEMA- 1796 202 12015 HEMA: PA: 1200 g/h MMA 1685 g/h (6.6 wt %) MMA: MEK: 1685 g/h 1695 g/h (9.2 wt %) 6 E-HEMA- 1795 201 12030 HEMA: PA: 1200 g/h MMA 1993 g/h (6.2 wt %) MMA: MEK: 1933 g/h 2200 g/h (10.0 wt %) 7 E-HEMA- 1794 200 12070 HEMA: PA: 1200 g/h MMA 2175 g/h (6.4 wt %) MMA: MEK: 2175 g/h 1100 g/h (11.6 wt %) 8 E-HEMA- 1795 201 12090 HEMA: PA: 1200 g/h MMA 2653 g/h (5.9 wt %) MMA: MEK: 2653 g/h 1600 g/h (13.1 wt %) 9 E-HEMA- 1795 200 11985 HEMA: PA: 1200 g/h MMA 520 g/h (7.0 wt %) MMA: MEK: 520 g/h 3000 g/h (3.0 wt %) 10 E-HEMA- 1800 200 12025 HEMA: PA: 1200 g/h MMA 1017 g/h (6.6 wt %) MMA: MEK: 1017 g/h 3000 g/h (5.6 wt %) 11 E-HEMA- 1801 201 12030 HEMA: PA: 1200 g/h EHA 1700 g/h (6.5 wt %) EHA: MEK: 1700 g/h 1700 g/h (9.3 wt %) 12 E-HEMA- 1800 200 12035 HEMA: PA: 1200 g/h EHA 1905 g/h (6.2 wt %) EHA: MEK: 1905 g/h 2200 g/h (9.9 wt %) 13 E-HEMA- 1800 200 12060 HEMA: PA: 1200 g/h EHA 2200 g/h (6.4 wt %) EHA: MEK: 2200 g/h 1100 g/h (11.7 wt %) 14 E-HEMA- 1800 200 12090 HEMA: PA: 1200 g/h EHA 2300 g/h (6.2 wt %) EHA: MEK: 2300 g/h 1600 g/h (11.8 wt %) 15 E-HEMA- 1796 200 12035 HEMA: PA: 1200 g/h EHA 490 g/h (7.0 wt %) EHA: MEK: 490 g/h 3000 g/h (2.8 wt %) 16 E-HEMA- 1798 200 12045 HEMA: PA: 1200 g/h EHA 992 g/h (6.6 wt %) EHA: MEK: 992 g/h 3000 g/h (5.4 wt %)
Characterization of the Liquid Ethylene Copolymers

(11) The molecular weight number distribution Mn and the molecular weight weight distribution Mw were determined via GPC. The polydispersity was calculated as PD=(Mw/Mn). The GPC analysis was made with a RI detector, a PLgel MIXED-B column (column temperature 35° C.) and THF with 0.1% trifluor acetic acid as elution medium. The calibration was done with very narrow distributed polystyrene standards from the Polymer Laboratories with a molecular weights M=from 580 until 6.870.000 g/mol.

(12) The amounts of monomomers which are present in polymerized form in the polymer was determined by H-NMR. The Kinematic Viscosity at 120° C. (V120) were determined according to ASTM D 445. The appearance of the liquid ethylene copolymers was determined visually. The Cloud Point CP was determined according to ISO 3015. The Pour Point PP was determined according to ASTM D 97.

(13) The results demonstrated that all ethylene copolymers were liquid at room temperature and had a pour point below 25° C. The results further indicate that all ethylene copolymers tend to have good low temperature characteristics because of their low cloud point. The results demonstrated that the ethylene copolymers have a desired high kinematic viscosity and is liquid at room temperature.

(14) TABLE-US-00002 TABLE 2 Analytical data of copolymers Amounts Mn Mw V120 Ex. Monomers [wt%] [g/mol] g/mol] PD [mm.sup.2/s] 1 E-HEMA-NBA 35-12-53 4090 8820 2.2 220 2 E-HEMA-NBA 38-34-28 3120 7 020 2.3 400 3 E-HEMA-NBA 34-34-32 3370 7 790 2.3 460 4 E-HEMA-NBA 35-21-44 3630 8 450 2.3 295 5 E-HEMA-MMA 39-30-31 2780 6190 2.2 1130 6 E-HEMA-MMA 35-30-35 2940 6690 2.3 1710 7 E-HEMA-MMA 40-40-20 2580 5660 2.2 855 8 E-HEMA-MMA 37-40-23 2760 6150 2.2 1410 9 E-HEMA-MMA 35-10-55 3290 7490 2.3 2035 10 E-HEMA-MMA 34-18-48 3290 7540 2.3 2504 11 E-HEMA-EHA 41-32-27 2720 6090 2.2 275 12 E-HEMA-EHA 36-32-32 2930 6880 2.3 330 13 E-HEMA-EHA 42-40-18 2870 5910 2.1 360 14 E-HEMA-EHA 41-37-22 2850 5950 2.1 300 15 E-HEMA-EHA 38-10-52 3090 7000 2.3 140 16 E-HEMA-EHA 36-18-46 3130 7160 2.3 200