PROCESS FOR PREPARING GRAFT COPOLYMER COMPRISING POLYETHYLENE

Abstract

The invention relates to a process for preparing a graft copolymer comprising polyethylene, comprising the steps of: A) providing an ethylene copolymer comprising side chains having CC bond and B) reacting the ethylene copolymer of step A) with an azide compound in the presence of a catalyst, a free radical initiator or diphenylamine to obtain the graft copolymer, wherein the azide compound is an azide compound having a functional group or a polymer having an azide group.

Claims

1. A process for preparing a graft copolymer comprising polyethylene, comprising the steps of: A) providing an ethylene copolymer comprising side chains having CC bond and B) reacting the ethylene copolymer of step A) with an azide compound in the presence of a catalyst, a free radical initiator or diphenylamine to obtain the graft copolymer, wherein the azide compound is an azide compound having a functional group or a polymer having an azide group.

2. The process according to claim 1, wherein the ethylene copolymer of step A) is reacted with the azide compound in step B) and the azide compound is represented by
N.sub.3-spacer.sup.1-FG.sup.1(I) wherein FG.sup.1 is selected from the group consisting of OH, OR.sup.5, NH.sub.2, NHR, NR.sup.5.sub.2, SH, CHCH.sub.2, ##STR00012## COOH, SO.sub.3H, NHCOR.sup.5, N.sub.3, Si(OR.sup.5).sub.3, ##STR00013## I, Br, Cl, F, COOR.sup.5, COR.sup.5, CN, -phenyl, C.sub.6H.sub.4R.sup.5, SC.sub.6H.sub.5 and COC.sub.6H.sub.5, where R.sup.5 is a C.sub.1-C.sub.10 linear or branched alkyl, spacer.sup.1 is selected from the group consisting of (CH.sub.2).sub.p, (CH.sub.2).sub.pC.sub.6H.sub.4, C.sub.6H.sub.4(CH.sub.2).sub.p, (CHR.sup.6).sub.p, (CR.sup.6.sub.2).sub.p, (OCH.sub.2CH.sub.2).sub.p, (OCH.sub.2CHCH.sub.3).sub.p, SO.sub.2, SO.sub.2C.sub.6H.sub.4, SO.sub.2C.sub.6H.sub.2R.sup.6.sub.2, C.sub.6H.sub.4, C.sub.6H.sub.2R.sup.6.sub.2, where p is an integer from 1 to 20 and where R.sup.6 is C.sub.1-C.sub.10 a linear or branched alkyl.

3. The process according to claim 1, wherein step A) involves preparing the 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 ##STR00014## 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 ##STR00015## wherein X.sup.2 is F, Cl, Br or I.

4. The process according to claim 3, wherein the comonomer having the CC bond is compound (I) or (III).

5. 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.3R.sup.4 stands for ##STR00016##

6. The process according to claim 1, wherein the comonomer having the CC bond is selected from the group consisting of propargyl acrylate, propargyl methacrylate, 2-methyl-acrylic acid 3-(cyclooct-2-ynyloxy)-propyl ester, 6-hepten-3-yn-1-ol, 3-methyl-1-penten-4-yn-3-ol, 2-methyl-6-hepten-3-yn-2-ol, 1-phenyl-4-penten-1-yne, 5-hexen-2-yn-1-ol, 3-(allyloxy)-1-propyne, allyl propiolate, 2-Nonynoic acid, 2-propen-1-yl ester, 2-methyl-1-hexen-3-yne and 2-methyl-1-buten-3-yne.

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

8. 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 in step A).

9. The process according to claim 1, wherein step A) involves grafting a compound having a CC bond to a base ethylene polymer which is an ethylene homopolymer or a copolymer of ethylene and -olefins with 3-12 carbon atoms.

10. The process according to claim 1, , wherein step B) is performed at a temperature between the melting point of the ethylene copolymer having CC bond and 250 C.

11. The process according to claim 1, wherein the ethylene copolymer of step A) 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.

12. A graft copolymer obtained by the process according to claim 1.

13. An article comprising the graft copolymer according to claim 12.

14. The article according to claim 13, wherein the article is a film; a molded article; an extruded article; an article made by 3D printing; an article made by compounding; a foam; a profile; an adhesive, a bitumen modifier; a sealant; a disposable diaper; a textile; or a polymer alloy.

15. The article according to claim 14, wherein the film is a packaging of bakery items, snack foods, consumer durables, agricultural film, shrink film, a medical packaging, an upholstery wrap, a disposable glove or a film made by encapsulation.

Description

EXAMPLES

[0176] Step (A)

[0177] A low density ethylene copolymer comprising a triple bond was prepared in a 100 mL autoclave in batch operation.

[0178] 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. The reaction conditions and the injected composition are summarized in Table 1.

[0179] 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

[0180] 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:

[0181] Detector: IR5 PolymerChar (filter: CH.sub.total, CH.sub.2, CH.sub.3)

[0182] Autosampler: Agilent 1200

[0183] High-temperature (linear) columns:

[0184] 3Shodex UT 806M (30 particle size, 10000 max. pore size) and

[0185] 1Shodex UT 807 (30 particle size, 20000 max. pore size) connected in series

[0186] Guard column:

[0187] Shodex UT-G (30 particle size)

[0188] Sample preparation for GPC:

[0189] sample concentration: 1.5 mg/ml

[0190] Mass of polymer sample: 10-20 mg (weighted in a 10 ml vial)+butylated

[0191] hydroxytoluene (BHT) as stabilizer

[0192] Solvent: 1,2,4-Trichlorobenzene (TCB)

[0193] Solvent volume added by autosampler: 8 mL

[0194] Solution temperature controlled by autosampler: 160 C.

[0195] Solution time controlled by autosampler: 60 min

[0196] Measurement conditions:

[0197] Injection volume: 200 L

[0198] Flow rate: 1.0 mL/min

[0199] Columns and detector temperature: 150 C.

[0200] Eluent: 1,2,4-Trichlorobenzene (TCB)

[0201] 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.

[0202] Standards for Polyethylene: Molar mass at peak maximum

[0203] PE(Mp) [g/mol]

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

[0204] Software:

[0205] Control software: PolymerChar GPC IR

[0206] Data processing software: PSS WinGPC Unity 7.4.0 (conventional calibration)

[0207] Wyatt ASTRA (light scattering)

[0208] Data processing:

[0209] dn/dc (at 658 nm): 0.104

[0210] plotting formalism: Zimm (1.sup.st order)

[0211] linear references: <R.sub.g.sup.2>.sup.1/2=0.0286*M.sup.0.575 [nm]

[0212] <>=0.053*M.sup.0.703 [mL/g]

[0213] Zimm-Stockmayer-model: trifunctional polydisperse

[0214] 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:

[0215] Bruker DRX 500 (500 MHz) spectrometer was used.

[0216] .sup.1H-NMR (500.13 MHz), .sup.13C-NMR (125.77 Mhz), 5 mm probe

[0217] .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

[0218] .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

[0219] 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.)

[0220] The results of HT-.sup.1H-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.

[0221] Hence, it can be confirmed that a copolymer of ethylene and PMA was obtained, comprising a triple bond.

[0222] Step (B)

[0223] A solution of the ethylene copolymer obtained in step A, solvent (see table), C.sub.6H.sub.5SCH.sub.2N.sub.3 and a solution of CuBr/PMDETA in acetonitrile was injected in a pressure cell for experiments at elevated pressure. The mixture was heated up to temperature (see table) and stirred for a certain time (see table). Afterwards, the reaction mixture was cooled and the polymer precipitated in acetone. Filtration and drying yielded the product.

TABLE-US-00004 Conversion of Exper- T Time Pressure click reaction n(N.sub.3)/n() iment Solvent ( C.) (hr) (bar) (%) (mol/mol) 1 ethane* 65 1 1500 >99 2.8 *not homogenous solution because of low temperature

[0224] It was confirmed by HT-.sup.1H-NMR that reaction has been taking place with a conversion listed in table. The HT-.sup.1H-NMR results of experiment 1 are shown in FIG. 2. Only one of the two different regioisomers of 1,2,3-triazoles is formed, namely the 1,4-regioisomer. All signals of the incorporated azide compound forming the 1,4-regioisomer can be clearly allocated via HT-.sup.1H-NMR as one can see in FIG. 2. The non-reacted triple bond in the copolymer is not visible anymore so therefore a conversion of >99% is assumed.

[0225] NMR Settings

[0226] HT-.sup.1H-NMR was carried out on the obtained copolymer at 80 C. using C.sub.2D.sub.2Cl.sub.4 as the solvent. Details of HT-.sup.1H-NMR are as follows:

[0227] Bruker Advance III HD 400 (400 MHz) spectrometer was used.

[0228] .sup.1H-NMR (400.13 MHz), 5 mm probe

[0229] .sup.1H-NMR: 90 pulse (10.0 s), spectral width 8.013 kHz, relaxation delay (d1) 5 s,

[0230] acquisition time 4.089 s, 16 Scans

[0231] used concentrations: 3.6 wt % (.sup.1H, C.sub.2D.sub.2Cl.sub.4, T=80 C.)