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 at an elevated temperature in the absence of a catalyst 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 at an elevated temperature in the absence of a catalyst to obtain the graft copolymer, wherein the azide 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, ##STR00011## COOH, SO.sub.3H, NHCOR.sup.5, N.sub.3, Si(OR.sup.5).sub.3, ##STR00012## 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 ##STR00013## 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.3R.sup.4 stands for ##STR00014## 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 ##STR00015##

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 C 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 300 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. The 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 packaging of bakery items, snack foods, consumer durables, an agricultural film, a shrink film, medical packaging, upholstery wrap, a disposable glove or a film made by encapsulation.

Description

[0194] 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.

[0195] Hence, it can be confirmed that a copolymer of ethylene and PMA was obtained, comprising a triple bond.

[0196] step (B)

[0197] A solution of the ethylene copolymer obtained in step A, solvent (see table) and C.sub.6H.sub.5SCH.sub.2N.sub.3 was injected in a pressure cell for experiments at elevated pressure (Ex 2, 3) or in a round bottom flask with reflux condenser for experiments at atmospheric pressure (Ex 1). The mixture was heated up to temperature (see table) and stirred for a certain time (see table). In Ex 1, the reaction mixture was subsequently cooled and the polymer precipitated in acetone. Filtration and drying yielded the product. In Ex 2 and 3, the product was collected from the pressure cell after depressurizing, dissolved in hot C.sub.2H.sub.2Cl.sub.4 and precipitated in acetone.

TABLE-US-00004 Conversion of thermal click T Time Pressure reaction n(N.sub.3)/n() Experiment Solvent ( C.) (hr) (bar) (%) (mol/mol) 1 C2H2Cl4 130 4 atmospheric 38 1.7 2 ethane 105 24 2000 91 7.6 3 ethylene 105 24 1800 40 3.7

[0198] 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 2 are shown in FIG. 2. For simplicity reasons, only one of the two different regioisomeric mixtures of 1,2,3-triazoles is shown (1,4-addition). All signals of the incorporated azide compound forming the two different regioisomeric mixtures of 1,2,3-triazoles can be clearly allocated via HT-.sup.1H-NMR as one can see in FIG. 2. Additionally, the non-reacted triple bond in the copolymer is also visible. Based on integration of the signals, a conversion of the thermal click reaction could be calculated.

[0199] NMR Settings

[0200] HT-.sup.1H-NMR was 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 are as follows:

[0201] Bruker Advance III HD 400 (400 MHz) spectrometer was used.

[0202] .sup.1H-NMR (400.13 MHz), 5 mm probe

[0203] .sup.1H-NMR: 90 pulse (29.4 s), spectral width 8.013 kHz, relaxation delay (d1) 5 s, acquisition time 4.089 s, 16 Scans

[0204] used concentrations: 3.6 wt % (.sup.1H, C.sub.2D.sub.2Cl.sub.4, T=100 C.)