Ethylene Vinyl Acetate Copolymer and Method of Preparing the Same

Patent metadata

Field	Value
Publication number	US-2020140586-A1
Application number	US-201816464469-A
Country	US
Kind code	A1
Filing date	Aug 31, 2018
Priority date	Dec 18, 2017
Publication date	May 7, 2020
Grant date	—

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

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 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 reactor>a temperature T 2 comprising one stage or more from the uppermost of the 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 reactor and an input temperature of the monomers input to the reactor.

5 . The method of claim 4 , wherein the 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 reactor, the T 2 is a temperature of a reaction region comprising four stages from the uppermost of the 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 the reaction at a temperature equal to or greater than 170° C. and equal to or less than 230° C., wherein the 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

• C08F2800/20

  as weight or mass percentages · CPC title

• C08F210/02 Primary

  Ethene · CPC title

• C08F2500/12

  Melt flow index or melt flow ratio · CPC title

• C08F2/44

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

• C08F2/01

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