Method for producing ethylene-carboxylic acid copolymer
In a method of producing an ethylene-carboxylic acid copolymer according to an embodiment of the present invention, a carboxylic acid monomer and a polar co-solvent are introduced separately into a mixing unit or stored together in a supply unit to form a mixture. The mixture and ethylene are injected into a reactor to be copolymerized. Reaction kinetic properties of the carboxylic acid monomer and the polar co-solvent are controlled to suppress a formation of by-products.
1. A method of producing an ethylene-carboxylic acid copolymer, comprising:
forming a mixture of a carboxylic acid monomer and a polar co-solvent that is an organic solvent; and
injecting the mixture and ethylene into a reactor to copolymerize the mixture and ethylene,
wherein the forming the mixture of the carboxylic acid monomer and the polar co-solvent includes adjusting a Reaction Progress Index (RPI) defined by Equation 1 in a range from 1.5 to 1.3×10 7 sec·K to control an amount of a side reaction product of the carboxylic acid monomer and the polar co-solvent:
RPI
=
C
s
olvent
C
m
onomer
t
T
[
Equation
1
]
wherein, in Equation 1, C solvent and C monomer are initial molar concentrations of the carboxylic acid monomer and the polar co-solvent, respectively, t represents a contact time of the carboxylic acid monomer and the polar co-solvent, and T represents an average contact temperature of the carboxylic acid monomer and the polar co-solvent before being reacted with ethylene.
2. The method according to claim 1 , wherein the reaction progress index is in a range from 14.9 to 1.3×10 5 sec·K.
3. The method according to claim 1 , further comprising discharging the mixture.
4. The method according to claim 3 , wherein a discharge pressure of the mixture is greater than a mixing pressure of the carboxylic acid monomer and the polar co-solvent.
5. The method according to claim 4 , wherein the discharge pressure is greater than a pressure in the reactor.
6. The method according to claim 3 , wherein the forming the mixture comprises introducing each of the carboxylic acid monomer and the polar co-solvent into a mixing unit,
wherein the discharging the mixture comprises:
transferring the mixture from the mixing unit to a discharge unit through a conveying flow path; and
discharging the mixture from the discharge unit through a discharge flow path.
7. The method according to claim 1 , wherein a temperature of the mixture is maintained to be greater than a crystallization temperature of the carboxylic acid monomer and less than a self-polymerization temperature of the carboxylic acid monomer.
8. The method according to claim 1 , wherein the mixture is in contact with ethylene before being injected into the reactor.
9. The method according to claim 1 , further comprising injecting a reaction inhibitor between the carboxylic acid monomer and the polar co-solvent into the mixture.
10. The method according to claim 9 , wherein the reaction inhibitor includes an amine-based compound.
11. The method according to claim 1 , further comprising injecting a chain transfer agent into the mixture through a front-end flow path of the reactor.
12. The method according to claim 11 , wherein the chain transfer agent includes a non-polar organic compound.
13. The method according to claim 12 , wherein the chain transfer agent includes methyl ethyl ketone or isobutane.
14. The method according to claim 11 , wherein Equation 2 is satisfied:
0.003 mol/L ≤Cs solvent C solvent r +Cs CTA C CTA r ≤0.01 mol/L [Equation 2]
wherein C solvent r and C CTA r are each molar ratio of the polar co-solvent and the chain transfer agent (CTA), respectively, at the front-end flow path of the reactor, and
Cs solvent and Cs CTA are each chain transfer coefficient (Cs) of the polar co-solvent and the chain transfer agent, respectively, with respect to ethylene at 200° C.
15. The method according to claim 1 , wherein the carboxylic acid monomer includes acrylic acid and the polar co-solvent includes ethanol.