Ethylene vinyl acetate copolymer and method of preparing the same

Patent metadata

Field	Value
Publication number	US-10961333-B2
Application number	US-201816464469-A
Country	US
Kind code	B2
Filing date	Aug 31, 2018
Priority date	Dec 18, 2017
Publication date	Mar 30, 2021
Grant date	Mar 30, 2021

Abstract

An ethylene vinyl acetate copolymer with a high degree of cross-linking and a method of preparing the same are provided, by controlling a temperature and polymerization heat in an autoclave reactor during polymerization, even when a reduced amount of a cross-linking agent is used.

First claim

The invention claimed is:

1. An ethylene vinyl acetate copolymer satisfying conditions (1) to (4) below:
(1) degree of cross-linking: 85% or greater
(2) content of vinyl acetate: 25 to 35 wt % based on total weight of the ethylene vinyl acetate copolymer
(3) melt index (190° C., 2.16 kg): 20 to 30 g/10 min
(4) ratio of η*/[η]: 5500 to 7500, and
wherein η* is complex viscosity at zero shear measured at 160° C. and [η] is intrinsic viscosity measured at 25° C.

2. The ethylene vinyl acetate copolymer of claim 1 , wherein the ethylene vinyl acetate copolymer has a number average molecular weight of 16,000 to 18,000 g/mol.

3. The ethylene vinyl acetate copolymer of claim 1 , wherein the ethylene vinyl acetate copolymer has a molecular weight distribution of 3.0 to 4.0.

4. A method of preparing the ethylene vinyl acetate copolymer of claim 1 , comprising
polymerizing an ethylene monomer and a vinyl acetate monomer in an autoclave reactor in the presence of an initiator,
wherein
the reactor comprises a reaction region with at least three stages satisfying the following temperature condition:
a temperature T 1 of a reaction region comprising one stage or more from the lowermost of the autoclave reactor>a temperature T 2 comprising one stage or more from the uppermost of the autoclave reactor>a temperature T 3 of a reaction region comprising one stage or more therebetween, and
ΔT/Q<2.5 is satisfied, wherein ΔT is a difference between T 1 and T 2 and Q is polymerization heat due to a temperature difference between a temperature of an ethylene vinyl acetate copolymer prepared in the autoclave reactor and an input temperature of the monomers input to the autoclave reactor.

5. The method of claim 4 , wherein the autoclave reactor comprises a reaction region with 11 stages, wherein the T 1 is a temperature of a reaction region comprising five stages from the lowermost of the autoclave reactor, the T 2 is a temperature of a reaction region comprising four stages from the uppermost of the autoclave reactor, and the T 3 is a temperature of a reaction region comprising two stages therebetween.

6. The method of claim 4 , wherein ΔT is greater than 0° C. and is equal to or less than 30° C.

7. The method of claim 4 , wherein Q is 10 to 15 gcal.

8. The method of claim 4 , wherein the temperature of T 1 is 180 to 220° C. and the temperature of T 2 is 160 to 190° C.

9. The method of claim 4 , wherein a pressure of the autoclave reactor is 1800 to 2100 bar.

10. The method of claim 4 , wherein an input temperature of monomers input into the autoclave reactor is 10 to 60° C.

11. The method of claim 4 , wherein the vinyl acetate monomer is comprised in an amount of 25 to 35 wt % based on a total weight of 100 wt % of an ethylene monomer and a vinyl acetate monomer.

12. The method of claim 4 , wherein the initiator comprises:
a low temperature initiator for initiating a reaction between the ethylene monomer and the vinyl acetate monomer at a temperature of equal to or greater than 130° C. and less than 170° C.; and
a high temperature initiator for initiating a reaction at a temperature equal to or greater than 170° C. and equal to or less than 230° C.,
wherein a weight ratio of the low temperature initiator to the high temperature initiator is from 5:95 to 95:5.

13. The method of claim 12 , wherein the low temperature initiator comprises 1,4-di(2-neodecanoylperoxyisopropyl)benzene, cumylperoxy neodecanoate, di(sec-butyl) peroxydicarbonate, di(n-butyl)peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, tert-amylperoxy neodecanoate, or tert-butyl peroxy neodecanoate, and
the high temperature initiator comprises tert-amylperoxy pivalate, tert-butylperoxy pivalate, di(3,5,5-trimethylhexanoyl) peroxide, tert-amylperoxy 2-ethylhexanoate, tert-butylperoxy 2-ethylhexanoate, tert-butylperoxy-isobutyrate, tert-butylperoxy-3,5,5-trimethylhexanoate or tert-butyl peroxyacetate.

Assignees

• Lg Chemical Ltd

Inventors

• Sung Yutaek
• Nam Youn Sun
• Joo Eun Jung
• Lee Choong Hoon
• Shin Dae Young
• Choi Sungho
• Yoon Juho
• Na Young Hoon
• Lee Hyojoon

Classifications

• C08F2500/17

  Viscosity · CPC title

• C08F2500/12

  Melt flow index or melt flow ratio · CPC title

• C08F210/02 Primary

  Ethene · CPC title

• C08F2/01

  characterised by special features of the polymerisation apparatus used · CPC title

• C08F2/44

  Polymerisation in the presence of compounding ingredients, e.g. plasticisers, dyestuffs, fillers · CPC title