METHOD FOR PREPARING ETHYLENE COPOLYMER

Abstract

A process for preparing an ethylene copolymer in the presence of free-radical polymerization initiator at pressures from 150 MPa to 350 MPa and temperatures from 100 C. to 350 C., by copolymerizing ethylene and a comonomer having a CC bond and optionally further comonomers, wherein the comonomer having the CC bond is represented by formula

##STR00001##

wherein R.sup.1 is hydrogen or methyl; X.sup.1 is COO or CONH; R.sup.2 is CH.sub.2O, OCO, Si(CH.sub.3).sub.2, Si(CH.sub.3).sub.2O or CR.sup.5R.sup.6 wherein R.sup.5 and R.sup.6 are independently selected from hydrogen, methyl, ethyl and hydroxyl;
n is an integer from 1 to 32 and R.sup.2 is same or different from each other when n is 2 to 32; and R.sup.3 is CC and R.sup.4 is hydrogen, C.sub.1-C.sub.10 linear or branched alkyl, C.sub.1-C.sub.10 linear or branched hydroxyalkyl or phenyl, or the unit R.sup.3-R.sup.4 stands for

##STR00002##

wherein X.sup.2 is F, Cl, Br or I.

Claims

1. A process for preparing an ethylene copolymer in the presence of free-radical polymerization initiator at pressures in the range of from 150 MPa to 350 MPa and temperatures in the range of from 100 C. to 350 C. by copolymerizing ethylene and a comonomer having a CC bond and optionally further comonomers, wherein the comonomer having the CC bond is represented by formula ##STR00007## wherein R.sup.1 is hydrogen or methyl; X.sup.1 is COO or CONH; R.sup.2 is CH.sub.2O, OCO, Si(CH.sub.3).sub.2, Si(CH.sub.3).sub.2O or CR.sup.5R.sup.6 wherein R.sup.5 and R.sup.6 are independently selected from hydrogen, methyl, ethyl and hydroxyl; n is an integer from 1 to 32 and R.sup.2 is same or different from each other when n is 2 to 32; and R.sup.3 is CC and R.sup.4 is hydrogen, C.sub.1-C.sub.10 linear or branched alkyl, C.sub.1-C.sub.10 linear or branched hydroxyalkyl or phenyl, or the unit R.sup.3-R.sup.4 stands for ##STR00008## wherein X.sup.2 is F, Cl, Br or I.

2. The process according to claim 1, wherein the comonomer having the CC bond is compound (I) wherein X.sup.1 is COO, R.sup.2 is CH.sub.2, n is from 1 to 22, and R.sup.3 is CC and R.sup.4 is methyl or hydrogen or R.sup.3-R.sup.4 stands for ##STR00009##

3. The process according to claim 1, wherein the comonomer having the CC bond is selected from the group consisting of propargyl acrylate, propargyl methacrylate and 2-methyl-acrylic acid 3-(cyclooct-2-ynyloxy)-propyl ester.

4. The process according to claim 1, wherein the comonomer having the CC bond is propargyl methacrylate or propargyl acrylate.

5. The process according to claim 4, wherein the copolymerization is performed at temperatures of 150 C. to 210 C. and at pressures from 160 MPa and 250 MPa.

6. The process according to claim 1, wherein the amount of the comonomer having the CC bond is 0.1-10 mol % of the total weight of ethylene and all comonomers.

7. The process according to claim 1, wherein the copolymerization is performed in the presence of a chain transfer agent selected from the group consisting of propionaldehyde, n-heptane, propylene, propane, isopropanol and acetone.

8. The process according to claim 1, wherein the process is performed in a high pressure tubular reactor.

9. The ethylene copolymer obtained by the process of claim 1.

10. The ethylene copolymer according to claim 9, wherein the ethylene copolymer has a number average molecular weight M.sub.n of at least 5.0 kg/mol and/or a weight average molecular weight M.sub.w of at least 50 kg/mol.

11. An article comprising the ethylene copolymer according to claim 9.

12. The article according to claim 11, wherein the article is a film or sheet.

13. The article according to claim 12, wherein the film is or is a component of food packaging, consumer durable packaging, disposable diapers, textiles, agricultural film, shrink film, medical packaging, cable insulations, mulching film, protective film, or polymer coatings.

14. The article according to claim 13, wherein the film or sheet has a thickness of 5 to 500 micrometers.

15. The article according to claim 11, wherein the article is an injection moulded article, a blow moulded article, a sheet vacuum formed article, or a polymer coating.

16. The article according to claim 15, wherein the article is a container, bottle, rigid packaging, pail, or tray.

Description

EXAMPLES

[0060] A low density ethylene copolymer comprising a triple bond was prepared in a 100 mL autoclave in batch operation.

[0061] In the first step, a solution of propargyl methacrylate (PMA) and n-heptane as a chain transfer agent was injected in the autoclave and further ethylene was charged in order to increase pressure up to about 1300 to 1500 bar. Subsequently a solution of tert-butyl peracetate (TBPA)/n-heptane was injected and the pressure was adjusted to 1900 bar.

[0062] The reaction conditions and the injected composition are summarized in Table 1.

[0063] Due to decomposition of the initiator the polymerization was started and a temperature rise was observed. After the reaction was finished, the pressure was released and the material was collected. The results are summarized in Table 2.

TABLE-US-00001 TABLE 1 T pressure ethylene PMA n-heptane TBPA C. bar mol % mol % mol % mol ppm Ex 1 190 1900 98.4 0.4 1.6 18

TABLE-US-00002 TABLE 2 M.sub.n M.sub.w conversion (kg/mol) (kg/mol) (%) Ex 1 12 84 3.5

[0064] M.sub.n and M.sub.w were determined by gel permeation chromatography (GPC). The GPC equipment was High-temperature GPC IR5 from Polymerchar with following details:

[0065] Detector: IR5 PolymerChar (filter: CH.sub.total, CH.sub.2, CH.sub.3)

[0066] Autosampler: Agilent 1200

[0067] High-temperature (linear) columns:

[0068] 3 Shodex UT 806M (30 particle size, 10000 max. pore size) and

[0069] 1 Shodex UT 807 (30 particle size, 20000 max. pore size) connected in series

[0070] Guard column:

[0071] Shodex UT-G (30 particle size)

[0072] Sample preparation for GPC:

[0073] sample concentration: 1.5 mg/ml

[0074] Mass of polymer sample: 10-20 mg (weighted in a 10 ml vial)+butylated hydroxytoluene (BHT) as stabilizer

[0075] Solvent: 1,2,4-Trichlorobenzene (TCB)

[0076] Solvent volume added by autosampler: 8 mL

[0077] Solution temperature controlled by autosampler: 160 C.

[0078] Solution time controlled by autosampler: 60 min

[0079] Measurement conditions:

[0080] Injection volume: 200 L

[0081] Flow rate : 1.0 mL/min

[0082] Columns and detector temperature: 150 C.

[0083] Eluent: 1,2,4-Trichlorobenzene (TCB)

[0084] The CH.sub.total signal from IR5 is used as concentration detector. A conventional calibration curve with polyethylene standards (compare following table) is used to convert the measured data to a molecular weight distribution.

[0085] Standards for Polyethylene: Molar mass at peak maximum

[0086] PE(Mp) [g/mol]

TABLE-US-00003 338 507 1180 2030 22000 33500 55000 73000 99000 126000 168276 558239 1050517

[0087] Software:

[0088] Control software: PolymerChar GPC IR

[0089] Data processing software: PSS WinGPC Unity 7.4.0 (conventional calibration)

[0090] Wyatt ASTRA (light scattering)

[0091] Data processing:

[0092] dn/dc (at 658nm): 0.104

[0093] plotting formalism: Zimm (1.sup.st order)

[0094] linear references: <R.sub.g.sup.2>.sup.1/2=0.0286*M.sup.0.575 [nm]

[0095] <>=0.053*M.sup.0.703 [mL/g]

[0096] Zimm-Stockmayer-model: trifunctional polydisperse

[0097] Further, HT-.sup.1H-NMR and HT-.sup.13C-NMR were carried out on the obtained copolymer at 100 C. using C.sub.2D.sub.2Cl.sub.4 as the solvent. Details of HT-.sup.1H-NMR and HT-.sup.13C-NMR are as follows:

[0098] Bruker DRX 500 (500 MHz) spectrometer was used.

[0099] .sup.1H-NMR (500.13 MHz), .sup.13C-NMR (125.77 Mhz), 5 mm probe

[0100] .sup.1H-NMR: 30 pulse (11.1 s), spectral width 10.33 kHz, relaxation delay (d1) 0.5 s, acquisition time 3.172 s, 64-80 Scans

[0101] .sup.13C-NMR: 30 pulse (7.4 s), spectral width 37.0 kHz, relaxation delay (d1) 0.4 s, acquisition time 0.8848 s, 2000-20000 Scans, .sup.1H-broad band decoupled

[0102] used concentrations: 1.1 wt % (.sup.1H, C.sub.2D.sub.2Cl.sub.4, T=100 C.), 6.8 wt % (.sup.13C, toluene, T=90 C.)

[0103] The results of HT-.sup.1H-NMR and HT-.sup.13C-NMR are shown in FIG. 1. All signals of the incorporated monomer and triple bond function can be clearly allocated via HT-.sup.1H-NMR and HT-.sup.13C-NMR, confirming the presence of the triple bond in the copolymer. In addition, the signals of 3-H.sub.2 and 1-H.sub.1 show a ratio of 2:1, which is the same supposed from the molecular structure. This indicates that the triple bond itself does not or only rarely undergo side or consecutive reactions.

[0104] Hence, it can be confirmed that a copolymer of ethylene and PMA was obtained, comprising a triple bond.

Experiment Set II

[0105] A copolymer of ethylene and propargyl acrylate (II-1) and a copolymer of ethylene and 3-(But-3-en-1-yloxy)cyclooct-1-yne (II-2) were prepared.

[0106] The synthesis of the copolymers was performed in a stirred 100 mL autoclave (900 rpm) which is running in batch operation mode. An overview of the used compounds is given in table 3.

TABLE-US-00004 TABLE 3 List of used compounds. compound manufacturer purity/class ethylene Air Liquide 3.0, catalytic purified propargyl acrylate Alfa Aesar 96% 3-(But-3-en-1- Syncom pure yloxy)cyclooct-1-yne TBPEH United Initiators techn. pure TAPP United Initiators 75% n-heptane Acros Organics 99+% nitrogen Westphal 5.0 MMAO-3A Dow Chemical 7 wt % in n-heptane TBPEH = tert-butyl peroxy-2-ethylhexanoate TAPP = tert-amyl peroxypivalate

[0107] Prior to polymerization the reactor Was purged. A MMAO-3A (modified methylaluminoxane) solution (13 mmol/L) was filled in the reactor and was stirred for 1 h at 300 bar and room temperature in order to minimize H.sub.2O and O.sub.2 content. Afterwards MMAO was removed by flushing with ethylenene for 10 min, 5 min and 5 min at 500 bar, 1000 bar and 1500 bar respectively. Then the pressure was reduced to 150 bar, the reactor was heated up and the experiment was started.

[0108] II-1 Copolymer of Ethylene and Propargyl Acrylate

[0109] The reaction conditions for the copolymerization with propargyl acrylate are summarized in table 2.

TABLE-US-00005 TABLE 4 Reaction conditions for the production of poly(etylene-co-propargyl acrylate) in the 100 mL autoclave. T p x(C.sub.2H.sub.4) x(PA) x(n-heptane) x(TBPEH) ( C.) (bar) (mol %) (mol %) (mol %) (mol ppm) 160 2000 97 0.4 2.6 36 PA = propargyl acrylate TBPEH = tert-butyl peroxy-2-ethylhexanoate

[0110] Mixtures of PA/n-heptane and TBPEH/n-heptane were filled in glass vials and stripped with nitrogen for several minutes. In parallel the injection line was evacuated and after that the PA/n-heptane solution was sucked in the line. The solution was injected together with ethylene into the reactor yielding a pressure of about 1100 bar. This was followed by the second injection with TBPEH/n-heptane to a pressure of about 2100 bar. Due to decomposition of the initiator the polymerization started and a temperature rise was caused. After the experiment was finished the pressure was released to 200 bar and the reactor was flushed at 500 bar for 5 min. The reactor was depressurized and the material was collected.

[0111] The obtained temperature and pressure profiles are given in FIG. 2.

[0112] II-2 copolymer of ethylene and 3-(But-3-en-1-yloxy)cyclooct-1-yne

[0113] The reaction conditions for the copolymerization with 3-(But-3-en-1-yloxy)cyclooct-1-yne are summarized in table 5.

TABLE-US-00006 TABLE 5 Reaction conditions for the production of poly(etylene-co-3-(But-3-en-1- yloxy)cyclooct-1-yne) in the 100 mL autoclave. x(n- T p x(C.sub.2H.sub.4) x(CoM) heptane) x(TAPP) ( C.) (bar) (mol %) (mol %) (mol %) (mol ppm) 110 2000 97.3 0.1 2.6 12 CoM = 3-(But-3-en-1-yloxy)cyclooct-1-yne TAPP = tert-amyl peroxypivalate

[0114] Mixtures of CoM/n-heptane and TAPP/n-heptane were filled in glass vials and stripped with nitrogen for several minutes. In parallel the injection line was evacuated and after that the CoM/n-heptane solution was sucked in the line. The solution was injected together with ethylene into the reactor yielding a pressure of about 1350 bar. This was followed by the second injection with TAPP/n-heptane to a pressure of about 2100 bar. Due to decomposition of the initiator the polymerization started and a temperature rise was caused. After the experiment is finished the pressure is released to 200 bar and the reactor was flushed at 500 bar for 5 min. The reactor was depressurized and the material was collected.

[0115] The obtained temperature and pressure profiles are given in FIG. 3.