Process for producing ethylene copolymer with improved efficiency

Abstract

The invention relates to process a process for preparing an ethylene copolymer and to a system for producing the ethylene copolymer.

Description

24POLY0090-WO-ORD1PROCESS FOR PRODUCING ETHYLENE COPOLYMER WITH IMPROVED EFFICIENCY FIELD OF INVENTION

[0001] The invention relates to a process of producing ethylene copolymers such as copolymers derived from ethylene and vinyl monomers such as 2-hydroxyethyl methacrylate (HEMA). The invention further relates to a system for preparing the ethylene based copolymers.BACKGROUND

[0002] One of the impediments facing the industrial scale production of ethylene copolymer is that of reactor fouling due to the self-polymerization of the comonomer. For example, it was observed that during the production of ethylene copolymers using vinyl monomers such as HEMA is the self-polymerization of comonomer which may occur in the preheater sections located upstream of the polymerization reactors. Such self-polymerization typically occurs when the comonomer is exposed to elevated temperature for example temperatures of about 75 °C - 163 °C. One of the reasons that cause self-polymerization and fouling is the temperature rise when the ethylene is mixed with the vinyl monomer such as acrylates in the reactor or in the upstream hardware such as compressor or the preheaters in a high pressure polymerization set up. Mitigating or temperature management of the mixing of the monomers is one suitable way of controlling fouling or thermal hotspots.

[0003] The self-polymerization results in a pre-polymer buildup on compressor parts and causes pre-polymer caking on the inner walls of tubing and piping leading to reduced production rates and reactor downtime. Self-initiation or self-polymerization of acrylate monomers have been investigated in the past. It is known that at temperatures as low as 80°C self-initiated polymerization may take place. For example, in the research publication titled “Self-Initiated Butyl Acrylate Polymerizations in Bulk and in Solution Monitored By In-Line Techniques’" (Polymers 2021, 13, 2021. https: / / doi.org / 10.3390 / polyml3122021), the publication describes that even at 80 °C, the butyl acrylate starts to self-polymerize (Pg 4 of 16 of the journal). Therefore, the temperature rise on mixing of vinyl-based monomers such as acrylates with ethylene needs to be kept at a suitable level to minimize the risk of self-polymerization and reactor fouling.24POLY0090-WO-ORD2

[0004] Further the publication titled “ Theoretical Insights Into Thermal Self-Initiation Reactions of Acrylates’’’ (DOI: https: / / doi.org / 10.1016 / B978-0-12-815983-5.00004-0, Computational Quantum Chemistry.) describes under section 4.4.1 that self-initiation or selfpolymerization of methyl methacrylate have been reported at a temperature between 100-130 °C. However, in order to manage the possible temperature rise on mixing of the monomers, cooling systems such as heat exchangers, extensive array of water jackets may have to be used. In some instances, inhibitor compounds may have to be used to manage any adverse reaction kinetics arising from temperature rise.

[0005] Alternatively, injection of the comonomer may be carried out as a diluted stream with the use of diluents, which allows injection of high amounts of comonomers at very low temperatures at different locations of reactor. However, this leads to high operational cost as often ethylene is required to be compressed to the reactor pressure together with the comonomer. Further reducing the temperature of the comonomer stream below a certain limit increases the viscosity of the monomer stream, rendering it difficult to be injected into a reactor. Further too low a temperature may affect reaction kinetics and affect the overall polymerization process with ethylene.

[0006] In another approach, ethylene copolymer production systems have relied on adding foulant inhibitor into the oil used to lubricate the hyper-compressor plunger used in compressing the ethylene feed. This approach is problematic. When the inhibitor is incorporated into the lubricant oil, it is difficult to control and manage the amount of inhibitor that actually reaches the areas where self-polymerization occurs. Although the use of inhibitors is promising there is still room for improving process efficiencies in order to mitigate the risks of reactor fouling.

[0007] As a further consideration, producing ethylene copolymer with units derived from low monomer content (e.g. 1 wt.% or below) can be a challenge as typically the monomer flow rate is low during the production of such ethylene copolymer. The low flow rate leads to increased residence time possibly leading to temperature rise of the monomer feed stream.

[0008] EP4375304A1 describes a process for the manufacture of ethylene copolymers at high pressure using a specific tubular reactor specification and high-pressure liquid injection of comonomers and modifiers. Although the patent addresses reactor fouling, it does not describe temperature management when ethylene and comonomer streams are mixed prior to24POLY0090-WO-ORD3polymerization. Neither does the patent teach how temperature rise can be managed when ethylene copolymer with units derived from low monomer content, is to be produced.

[0009] As a further consideration, to improve reaction kinetics, the ethylene and the comonomer streams can be mixed in the preheater. The mixing of the ethylene and the comonomer in the preheater is beneficial for several reasons. The premixing of the ethylene and the vinyl comonomer feed in the preheater allows (a) initiation temperature control - and ensures that the entire feed entering the polymerization reactor to have uniform temperature, (b) mixing in the preheater ensures uniform distribution of ethylene and comonomer and any chain transfer agents, (c) increased conversion efficiency, (d) prevention of phase separation and reduced gel formation tendency. However as noted in the patent EP4375304A1 - the presence of high reactive comonomers increases fouling due to thermal polymerization at the tube inside wall, mainly of the comonomer, where the highest temperature is reached. The addition of inhibitor typically is not solving the problem as the efficiency of the inhibitor reduces significantly at the preheating temperatures. Further, the addition of comonomers directly in the polymerization reactor may also cause reactor fouling as the reactor is generally operating at high temperature.

[0010] Accordingly, it is an objective of the present invention to provide for a process of producing ethylene copolymers with minimal reactor fouling and avoiding thermal runaway reactions. It is yet another objective of the present invention to manage the temperature rise when ethylene and comonomers streams are mixed prior to polymerization in a polymerization reactor. It is yet another objective of the present invention to produce ethylene copolymers with units derived from low monomer content (e.g. 1 wt.% of below) while limiting the temperature rise on mixing the ethylene stream with the comonomer stream prior to polymerization. It is yet another objective of the present invention is to provide for a system of producing ethylene copolymer.BRIEF DESCRIPTION OF THE DRAWINGS

[0001] For a more complete understanding, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0002] FIG. 1 is a schematic diagram illustrating an overview of the system for the production of ethylene copolymer in accordance with the present invention where the comonomer stream is injected in the first preheater (4a).24POLY0090-WO-ORDDESCRIPTION

[0011] Accordingly, the one or more objectives of the present invention is achieved by a process for preparing an ethylene copolymer, the process comprising:(a) injecting an ethylene feed stream (1) into a compressor unit (2) to obtain an ethylene feed stream (3) comprising ethylene monomer, preferably wherein the ethylene feed stream (3) has a pressure of >180 MPa and < 320 MPa;(b) feeding at least a portion of the ethylene feed stream (3) into a first preheater (4a) positioned downstream to the compressor unit (2);(c) feeding a comonomer stream (5) comprising a vinyl monomer (D) into the first preheater (4a) such that the comonomer stream (5) is supplied to the first preheater (4a) by means of a dosing line (12) that is in fluid communication with the first preheater (4a);(d) contacting the ethylene feed stream (3) and the comonomer stream (5) and subsequently mixing the streams to obtain a product stream (6);(e) feeding at least a portion of the product stream (6) into a second preheater (4b) to obtain a product stream (8);(f) feeding the product stream (8) into a reactor (20) positioned downstream to the second preheater (4b) and polymerizing the ethylene monomer and the vinyl monomer (D) to obtain the ethylene copolymer; and• wherein the comonomer stream (5) comprising a vinyl monomer (D) is injected into the first preheater (4a) at a flow rate of > 20 and < 2500 kg / hr, preferably > 20 and < 1000 kg / hr, preferably > 50 and < 1000 kg / hr, preferably > 50 and < 500 kg / hr, preferably > 60 and < 300 kg / hr; and• wherein the temperature (Th) of the comonomer stream (5) in the dosing line (12) prior to injecting into the first preheater (4a) ranges from > 30 °C and < 80 °C, preferably > 30 °C and < 70 °C; and• wherein the comonomer stream (5) on contacting with the ethylene feed stream (3) has a temperature of > 55 °C and < 90 °C, preferably > 60 °C and < 90 °C, preferably > 60 °C and < 82 °C, preferably > 60 °C and < 78 °C.24POLY0090-WO-ORD5

[0012] Preferably, the process for preparing the ethylene copolymer, comprises:(a) injecting an ethylene feed stream (1) into a compressor unit (2) to obtain an ethylene feed stream (3) comprising ethylene monomer, preferably wherein the ethylene feed stream (3) has a pressure of >180 MPa and < 320 MPa;(b) feeding at least a portion of the ethylene feed stream (3) into a first preheater (4a) positioned downstream to the compressor unit (2);(c) feeding a comonomer stream (5) comprising a vinyl monomer (D) into the first preheater (4a) such that the comonomer stream (5) is supplied to the first preheater (4a) by means of a dosing line (12) that is in fluid communication with the first preheater (4a);(d) contacting the ethylene feed stream (3) and the comonomer stream (5) and subsequently mixing the streams to obtain a product stream (6);(e) feeding at least a portion of the product stream (6) into a second preheater (4b) to obtain a product stream (8);(f) feeding the product stream (8) into a reactor (20) positioned downstream to the second preheater (4b) and polymerizing the ethylene monomer and the vinyl monomer (D) to obtain the ethylene copolymer; and• wherein the comonomer stream (5) comprising a vinyl monomer (D) is injected into the first preheater (4a) at a flow rate of > 20 and < 2500 kg / hr, preferably > 20 and < 1000 kg / hr, preferably > 50 and < 1000 kg / hr, preferably > 50 and < 500 kg / hr, preferably > 60 and < 300 kg / hr; and• wherein the temperature (Th) of the comonomer stream (5) in the dosing line (12) prior to injecting into the first preheater (4a) ranges from > 30 °C and < 80 °C, preferably > 30 °C and < 70 °C; and• wherein the comonomer stream (5) on contacting with the ethylene feed stream (3) has a temperature of > 55 °C and < 90 °C, preferably > 60 °C and < 90 °C, preferably > 60 °C and < 82 °C, preferably > 60 °C and < 78 °C; and• wherein the vinyl-based monomer (D) is an acrylate based monomer (A) or an acrylate based ionomer (IA), preferably the vinyl based monomer (D) is an acrylate based monomer (A).24POLY0090-WO-ORD6

[0013] Preferably, the process for preparing the ethylene copolymer, comprises:(a) injecting an ethylene feed stream (1) into a compressor unit (2) to obtain an ethylene feed stream (3) comprising ethylene monomer, preferably wherein the ethylene feed stream (3) has a pressure of >180 MPa and < 320 MPa;(b) feeding at least a portion of the ethylene feed stream (3) into a first preheater (4a) positioned downstream to the compressor unit (2);(c) feeding a comonomer stream (5) comprising a vinyl monomer (D) into the first preheater (4a) such that the comonomer stream (5) is supplied to the first preheater (4a) by means of a dosing line (12) that is in fluid communication with the first preheater (4a);(d) contacting the ethylene feed stream (3) and the comonomer stream (5) and subsequently mixing the streams to obtain a product stream (6);(e) feeding at least a portion of the product stream (6) into a second preheater (4b) to obtain a product stream (8);(f) feeding the product stream (8) into a reactor (20) positioned downstream to the second preheater (4b) and polymerizing the ethylene monomer and the vinyl monomer (D) to obtain the ethylene copolymer; and• wherein the comonomer stream (5) comprising a vinyl monomer (D) is injected into the first preheater (4a) at a flow rate of > 50 and < 500 kg / hr, preferably > 60 and < 300 kg / hr; and• wherein the temperature (Th) of the comonomer stream (5) in the dosing line (12) prior to injecting into the first preheater (4a) ranges from preferably > 30 °C and < 70 °C; and• wherein the comonomer stream (5) on contacting with the ethylene feed stream (3) has a temperature of > 60 °C and < 82 °C, preferably > 60 °C and < 78 °C; and• wherein the vinyl based monomer (D) is an acrylate based monomer (A).

[0014] Preferably, the process for preparing the ethylene copolymer, comprises:24POLY0090-WO-ORD7(a) injecting an ethylene feed stream (1) into a compressor unit (2) to obtain an ethylene feed stream (3) comprising ethylene monomer, preferably wherein the ethylene feed stream (3) has a pressure of >180 MPa and < 320 MPa;(b) feeding at least a portion of the ethylene feed stream (3) into a first preheater (4a) positioned downstream to the compressor unit (2);(c) feeding a comonomer stream (5) comprising a vinyl monomer (D) into the first preheater (4a) such that the comonomer stream (5) is supplied to the first preheater (4a) by means of a dosing line (12) that is in fluid communication with the first preheater (4a);(d) contacting the ethylene feed stream (3) and the comonomer stream (5) and subsequently mixing the streams to obtain a product stream (6);(e) feeding at least a portion of the product stream (6) into a second preheater (4b) to obtain a product stream (8);(f) feeding the product stream (8) into a reactor (20) positioned downstream to the second preheater (4b) and polymerizing the ethylene monomer and the vinyl monomer (D) to obtain the ethylene copolymer; and• wherein the comonomer stream (5) comprising a vinyl monomer (D) is injected into the first preheater (4a) at a flow rate of > 60 and < 300 kg / hr; and• wherein the temperature (Th) of the comonomer stream (5) in the dosing line (12) prior to injecting into the first preheater (4a) ranges from preferably > 30 °C and < 70 °C; and• wherein the comonomer stream (5) on contacting with the ethylene feed stream (3) has a temperature of > 60 °C and < 82 °C, preferably > 60 °C and < 78 °C; and• wherein the vinyl based monomer (D) is an acrylate based monomer (A).

[0015] The invention now provides a process to prepare ethylene copolymer, while managing the temperature rise on mixing the ethylene with the vinyl monomer by injecting the vinyl monomer at a suitable location in a two-preheater set up each located upstream to the polymerization reactor. Further the temperature rise is managed by controlling the flow rate of the24POLY0090-WO-ORD8comonomer stream, temperature of the monomer stream and optionally the temperature of the ethylene stream when the monomer stream is introduced.

[0016] Advantageously, the process of the present invention enables a skilled person to produce ethylene copolymers with minimal reactor fouling and avoiding thermal runaway reactions.

[0017] Further, the process of the present invention now allows a skilled person to manage the temperature rise when ethylene and comonomers streams are mixed prior to polymerization. As a further advantage, the process of the present invention now allows a skilled person to produce ethylene copolymer with units derived from low monomer content (e.g. 1 wt.% of below) while limiting risks of reactor fouling. Managing the temperature rise when ethylene and vinyl monomer is mixed is an important factor in the entire production process, as not only reactor fouling and poor reaction kinetics is observed if the rise of temperature is not regulated but also the final ethylene copolymer has inconsistent properties.

[0018] Therefore, lower the spike in temperature in the preheater, lower are the risk of self-polymerization and poor reaction kinetics. For example, based on existing literature survey as described in the above section, when using acrylate based monomers, it is preferred that temperature on mixing does not exceed 90 °C, preferably does not exceed 85 °C, preferably does not exceed 80 °C to prevent any possibilities of self-polymerization.

[0019] As a further advantage the process of the present invention enables a skilled person to mix the ethylene and comonomer streams in the preheater itself ensuring the one or more benefits of improved reaction kinetics better monomer dispersion while managing any rise in temperature during the mixing of the streams.

[0020] The reactor (20) can be any suitable reactor such as an autoclave reactor, a tubular reactor, or a combination of an autoclave reactor in operative communication with a tubular reactor. The pre-heater heats the polymerization reactor (20) contents prior to injection of the free-radical initiator. The first preheater (4a) may be a water preheater. The injection of the comonomer stream (5) into the first preheater may be carried out using a suitable injection device such as a torpedo mixer as described in EP3565659A1 with the device comprising the annular part, a support structure, an injector part, and a supply channel. The temperature of the ethylene stream or the comonomer stream (5) may be measured using a sensor or a thermocouple.24POLY0090-WO-ORD9

[0021] In some embodiments of the invention, the polymerization reaction may for example can take place in the tubular reactor using the high pressure CTR ™ technology as described in Chapter 7.9 of “Handbook of Petrochemicals Production Processes, 2nd Edition” (ISBN: 9781259643132).

[0022] Advantageously, the process as described in the present invention enables a skilled person to produce ethylene copolymers without causing reactor fouling.

[0023] Preferably, the comonomer stream (5) comprising the vinyl monomer (D), is injected into the first preheater (4a) at a flow rate of > 50 and < 1000 kg / hr, preferably > 50 and < 500 kg / hr, preferably > 60 and < 300 kg / hr, preferably > 60 and < 75 kg / hr.

[0024] Preferably, the process for preparing the ethylene copolymer, comprises:(a) injecting an ethylene feed stream (1) into a compressor unit (2) to obtain an ethylene feed stream (3) comprising ethylene monomer, preferably wherein the ethylene feed stream (3) has a pressure of >180 MPa and < 320 MPa;(b) feeding at least a portion of the ethylene feed stream (3) into a first preheater (4a) positioned downstream to the compressor unit (2);(c) feeding a comonomer stream (5) comprising a vinyl monomer (D) into the first preheater (4a) such that the comonomer stream (5) is supplied to the first preheater (4a) by means of a dosing line (12) that is in fluid communication with the first preheater (4a);(d) contacting the ethylene feed stream (3) and the comonomer stream (5) and subsequently mixing the streams to obtain a product stream (6);(e) feeding at least a portion of the product stream (6) into a second preheater (4b) to obtain a product stream (8);(f) feeding the product stream (8) into a reactor (20) positioned downstream to the second preheater (4b) and polymerizing the ethylene monomer and the vinyl monomer (D) to obtain the ethylene copolymer; and• wherein the comonomer stream (5) comprising a vinyl monomer (D) is injected into the first preheater (4a) at a flow rate of > 60 and < 75 kg / hr; and• wherein the temperature (Th) of the comonomer stream (5) in the dosing line (12) prior to injecting into the first preheater (4a) ranges from preferably > 30 °C and < 70 °C; and24POLY0090-WO-ORD10• wherein the comonomer stream (5) on contacting with the ethylene feed stream (3) has a temperature of > 60 °C and < 78 °C; and• wherein the vinyl based monomer (D) is an acrylate based monomer (A).

[0025] Preferably, the comonomer stream (5) comprising the vinyl monomer (D), is injected into the first preheater (4a) at a concentration of > 0.01 wt.% and < 0.65 wt.%, preferably > 0.05 wt.% and < 0.65 wt.%, preferably > 0.1 wt.% and < 0.6 wt.%, with regard to the total weight of the ethylene feed stream (3).

[0026] Preferably, the first preheater (4a) is operated at a temperature of > 80 °C and < 120 °C, preferably > 80 °C and < 100 °C and the second preheater (4b) is operated at a temperature of > 110 °C and < 170 °C, preferably > 120 °C and < 140 °C, preferably > 125 °C and < 140 °C.

[0027] Preferably, the first preheater (4a) is operated at a temperature of > 80 °C and < 100 °C and the second preheater (4b) is operated at a temperature of > 120 °C and < 140 °C, preferably > 125 °C and < 140 °C.

[0028] It is preferred that the second preheater is operated at temperature higher than the first preheater such that the temperature of the feed entering the reactor is closer to the temperature at which the polymerization takes place.

[0029] Preferably the temperature (Th) of the comonomer stream (5) in the dosing line (12) prior to injecting into the first preheater (4a) ranges from > 35 °C and < 65 °C, preferably > 40 °C and < 65 °C.

[0030] In an aspect of the invention, the comonomer stream (5) comprises > 95.0 wt.%, preferably > 98.0 wt.%, based on the total weight of comonomer stream (5) of the vinyl monomer (D).

[0031] Preferably, the ethylene copolymer comprises with regard to the total weight of the ethylene copolymer of:(i) > 94.0 and < 99.9 wt.%, preferably > 96.0 and < 99.7 wt.%, preferably > 97.0 and < 99.7 wt.%, of polymeric units derived from ethylene; and(ii) > 0.1 and < 6.0 wt.%, preferably > 0.3 and < 4.0 wt.%, preferably > 0.3 and <3.0 wt.% of polymeric units derived from the vinyl-based monomer (D).24POLY0090-WO-ORD11

[0032] Preferably, the ethylene copolymer comprises with regard to the total weight of the ethylene copolymer of > 96.0 and < 99.7 wt.%, of polymeric units derived from ethylene; and > 0.3 and < 4.0 wt.% of polymeric units derived from the vinyl-based monomer (D). Preferably wherein the content of ethylene and vinyl based monomer (D) is determined using13C NMR and / or 'H NMR.

[0033] Preferably wherein the ethylene copolymer consists of with regard to the total weight of the ethylene copolymer, of > 99.0 and < 99.7 wt.%, of polymeric units derived from ethylene; and > 0.3 and < 1.0 wt.% of polymeric units derived from the vinyl-based monomer (D). Most preferably the ethylene copolymer consists of, with regard to the total weight of the ethylene copolymer, of > 99.2 and < 99.7 wt.%, of polymeric units derived from ethylene; and > 0.3 and < 0.8 wt.% of polymeric units derived from the vinyl-based monomer (D).

[0034] Preferably, the ethylene stream (3) is fed to the first preheater (4a) at a flow rate of > 50 and < 120 tons / hour, preferably > 60 and < 100 tons / hour; and / or wherein the ethylene stream (3) in the first preheater (4a) has a temperature (Te) of > 80 °C and < 100 °C.

[0035] Preferably, the ethylene stream (3) is fed to the first preheater (4a) at a flow rate of > 50 and < 120 tons / hour, preferably > 60 and < 100 tons / hour; and wherein the ethylene stream (3) in the first preheater (4a) has a temperature (Te) of > 80 °C and < 100 °C.

[0036] Preferably, the reaction of the ethylene monomer with the vinyl monomer (D) is carried out in the reactor (20) at any pressure of >180 MPa and <350 MPa, preferably > 200 MPa and < 300 MPa and at any temperature of >100 °C and < 350 °C, preferably >125 °C and <310 °C, preferably >130 °C and < 300 °C; and / or wherein the reactor (20) is a tubular reactor.

[0037] Preferably the comonomer stream (5) comprising the vinyl monomer (D) is inj ected into the first preheater (4a) at a flow rate of > 60 and < 1000 kg / hr, preferably > 60 and < 300 kg / hr, preferably > 60 and < 75 kg / hr; and (ii) the comonomer stream (5) on contacting with the ethylene feed stream (3) has a temperature of > 60 °C and < 90 °C; (iii) the temperature (Th) of the comonomer stream (5) in the dosing line (12) and prior to injecting into the first preheater (4a) ranges from > 35 °C and < 65 °C; and (iv) wherein the ethylene stream (3) in the preheater24POLY0090-WO-ORD12(4a) has a temperature (Te) of > 80 °C and < 100 °C; and (v) wherein the comonomer stream (5) comprising the vinyl monomer (D), is injected into the first preheater (4a) at a concentration of > 0.01 wt.% and < 0.65 wt.%, preferably > 0.05 wt.% and < 0.65 wt.%, preferably > 0.1 wt.% and < 0.6 wt.%, with regard to the total weight of the ethylene feed stream (3); and wherein the ethylene copolymer comprises with regard to the total weight of the ethylene copolymer of > 96.0 and < 99.7 wt.%, of polymeric units derived from ethylene; and > 0.3 and < 4.0 wt.% of polymeric units derived from the vinyl based monomer (D), most preferably wherein the ethylene copolymer consists of with regard to the total weight of the ethylene copolymer, of > 99.2 and < 99.7 wt.%, of polymeric units derived from ethylene; and > 0.3 and < 0.8 wt.% of polymeric units derived from the vinyl-based monomer (D).

[0038] Preferably the comonomer stream (5) comprising the vinyl monomer (D) is inj ected into the first preheater (4a) at a flow rate of > 60 and < 300 kg / hr, preferably > 60 and < 75 kg / hr; and (ii) the comonomer stream (5) on contacting with the ethylene feed stream (3) has a temperature of > 60 °C and < 90 °C; (iii) the temperature (Th) of the comonomer stream (5) in the dosing line (12) and prior to injecting into the first preheater (4a) ranges from > 35 °C and < 65 °C; and (iv) wherein the ethylene stream (3) in the preheater (4a) has a temperature (Te) of > 80 °C and < 100 °C; and (v) wherein the comonomer stream (5) comprising the vinyl monomer (D), is injected into the first preheater (4a) at a concentration of > 0.01 wt.% and < 0.65 wt.%, preferably > 0.05 wt.% and < 0.65 wt.%, preferably > 0.1 wt.% and < 0.6 wt.%, with regard to the total weight of the ethylene feed stream (3); and wherein the ethylene copolymer consists of with regard to the total weight of the ethylene copolymer, of > 99.2 and < 99.7 wt.%, of polymeric units derived from ethylene; and > 0.3 and < 0.8 wt.% of polymeric units derived from the vinylbased monomer (D).

[0039] Preferably, the comonomer stream (5) is mixed with one or more inhibitor compound prior to injecting the comonomer stream (5) into the first preheater (4a). In some embodiments no inhibitor compounds were added into the preheater (4a).24POLY0090-WO-ORDVinyl Monomer D

[0040] Preferably, the vinyl based monomer (D) is an acrylate based monomer (A) or an acrylate based ionomer (IA).

[0041] In an aspect of the invention, wherein the vinyl based monomer (D) is an acrylate based monomer (A) having a structure represented by the formula (II) or by formula (III):a) wherein the formula (II) is:• R14 is a moiety selected from the group consisting of: — CH2 — ; — [CH2]x — CH(CH3) — , wherein x >1 and <10; — CH2 — CHR4-[O — CH2 — CHRa]q — , wherein q >1 and < 10, and each Ra individually is selected from CH3 or H; and — CH2 — CH(OH)— CH2— ;• R10 is selected from — H or — CH3;• R11 is selected from — O — , — (CO) — (NH) — or — (CO) — O — ;• n=0 or 1; and• m >1 and <10; andb) wherein the formula (III) is:24POLY0090-WO-ORD14• R16 is a moiety selected from the group consisting of: — CH2 — ; — [CH2]x — CH(CH3) — , wherein x >1 and <10; — CH2 — CHR4-[O — CH2 — CHRb]q— , wherein q >1 and <10, and each Rb individually is selected from CH3 or H; and — CH2 — CH(OH) — CH2 — ; • n >1 and <10; and• each R15 or R17 may individually be selected from — H or — CH3.

[0042] Preferably, the vinyl based monomer (D) is an acrylate based monomer (A) selected from the group consisting of 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2,3 -dihydroxypropyl acrylate, 2,3 -dihydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, polypropylene glycol) monoacrylate, poly(propyleneglycol) monomethacrylate, poly(ethylene glycol) monoacrylate, poly(ethylene glycol) monomethacrylate, poly(ethylenepropyleneglycol) monomethacrylate and 2-hydroxyethyl vinyl ether, 1,4-butanediol dimethacrylate, hexanediol dimethacrylate, ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, dodecanediol dimethacrylate, glycerol dimethacrylate, 1,4-butanediol diacrylate, hexanediol diacrylate, ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, dodecanediol diacrylate, glycerol diacrylate, glycerol 1,3 -di glycerolate diacrylate, glycerol 1,3-diglycerolate dimethacrylate, poly(ethylene glycol) dimethacrylate, polypropylene glycol) dimethacrylate, poly thylenepropyleneglycol) dimethacrylate, 1,4-butanediol divinyl ether, polypthylene glycol) divinyl ether, di(ethyleneglycol) divinyl ether, 1,5-hexadiene, 1,7-octadiene, 1,9-decadiene and 1,13 -tetradecadiene, preferably wherein the vinyl24POLY0090-WO-ORD15based monomer (D) is an acrylate based monomer (A) selected from 2 -hydroxy ethyl methacrylate, 1,4-butanediol dimethacrylate and combinations thereof.

[0043] Preferably wherein the acrylate monomer is 2-hydroxyethyl methacrylate. In other words, the vinyl monomer (D) is 2-hydroxyethyl methacrylate. Preferably, the ethylene copolymer comprises polymeric units derived from ethylene and 2-hydroxyethyl methacrylate.

[0044] Preferably, (i) the comonomer stream (5) comprising the vinyl monomer (D) is injected into the first preheater (4a) at a flow rate of > 60 and < 300 kg / hr; and (ii) the comonomer stream (5) on contacting with the ethylene feed stream (3) has a temperature of > 60 °C and < 90 °C; and (iii) the temperature of the comonomer stream (5) in the dosing line (12) and prior to injecting into the first preheater (4a) ranges from > 35 °C and < 65 °C and (iii) wherein the vinyl based monomer (D) is 2-hydroxyethyl methacrylate; and (iv) wherein the ethylene copolymer comprises with regard to the total weight of the ethylene copolymer of > 97.0 and < 99.5 wt.%, of polymeric units derived from ethylene; and > 0.5 and < 3.0 wt.% of polymeric units derived from the vinyl based monomer (D).

[0045] Preferably, wherein the comonomer stream (5) comprising 2-hydroxyethyl methacrylate (HEMA) is injected into the first preheater (4a) at a flow rate of > 60 and < 1000 kg / hr, preferably > 60 and < 300 kg / hr; and (ii) the comonomer stream (5) on contacting with the ethylene feed stream (3) has a temperature of > 60 °C and < 90 °C; and (iii) the temperature (Th) of the comonomer stream (5) in the dosing line (12) and prior to injecting into the first preheater (4a) ranges from > 35 °C and < 65 °C; and (iv) wherein the ethylene stream (3) in the preheater (4a) has a temperature (Te) of > 80 °C and < 100 °C; and (v) wherein the comonomer stream (5) comprising 2-hydroxyethyl methacrylate, is injected into the first preheater (4a) at a concentration of > 0.01 wt.% and < 0.65 wt.%, preferably > 0.05 wt.% and < 0.65 wt.%, preferably > 0.1 wt.% and < 0.6 wt.%, with regard to the total weight of the ethylene feed stream (3); and wherein the ethylene copolymer comprises with regard to the total weight of the ethylene copolymer of > 96.0 and < 99.7 wt.%, of polymeric units derived from ethylene; and > 0.3 and < 4.0 wt.% of polymeric units derived from 2-hydroxyethyl methacrylate.

[0046] Preferably the comonomer stream (5) comprising the vinyl monomer (D) is inj ected into the first preheater (4a) at a flow rate of > 60 and < 300 kg / hr, preferably > 60 and < 75 kg / hr; and (ii) the comonomer stream (5) on contacting with the ethylene feed stream (3) has a24POLY0090-WO-ORD16temperature of > 60 °C and < 90 °C; (iii) the temperature (Th) of the comonomer stream (5) in the dosing line (12) and prior to injecting into the first preheater (4a) ranges from > 35 °C and < 65 °C; and (iv) wherein the ethylene stream (3) in the preheater (4a) has a temperature (Te) of > 80 °C and < 100 °C; and (v) wherein the comonomer stream (5) comprising 2-hydroxy ethyl methacrylate, is injected into the first preheater (4a) at a concentration of > 0.01 wt.% and < 0.65 wt.%, preferably > 0.05 wt.% and < 0.65 wt.%, preferably > 0.1 wt.% and < 0.6 wt.%, with regard to the total weight of the ethylene feed stream (3); and wherein the ethylene copolymer consists of with regard to the total weight of the ethylene copolymer, of > 99.2 and < 99.7 wt.%, of polymeric units derived from ethylene; and > 0.3 and < 0.8 wt.% of polymeric units derived from 2-hydroxy ethyl methacrylate.

[0047] Preferably the comonomer stream (5) comprising the vinyl monomer (D) is inj ected into the first preheater (4a) at a flow rate of preferably > 60 and <75 kg / hr; and (ii) the comonomer stream (5) on contacting with the ethylene feed stream (3) has a temperature of > 60 °C and < 90 °C; (iii) the temperature (Th) of the comonomer stream (5) in the dosing line (12) and prior to injecting into the first preheater (4a) ranges from > 35 °C and < 65 °C; and (iv) wherein the ethylene stream (3) in the preheater (4a) has a temperature (Te) of > 80 °C and < 100 °C; and (v) wherein the comonomer stream (5) comprising 2-hydroxy ethyl methacrylate, is injected into the first preheater (4a) at a concentration of > 0.01 wt.% and < 0.65 wt.%, with regard to the total weight of the ethylene feed stream (3); and wherein the ethylene copolymer consists of with regard to the total weight of the ethylene copolymer, of > 99.2 and < 99.7 wt.%, of polymeric units derived from ethylene; and > 0.3 and < 0.8 wt.% of polymeric units derived from 2-hydroxy ethyl methacrylate.

[0048] Preferably the comonomer stream (5) comprising the vinyl monomer (D) is inj ected into the first preheater (4a) at a flow rate of preferably > 60 and <75 kg / hr; and (ii) the comonomer stream (5) on contacting with the ethylene feed stream (3) has a temperature of > 60 °C and < 78 °C; (iii) the temperature (Th) of the comonomer stream (5) in the dosing line (12) and prior to injecting into the first preheater (4a) ranges from > 35 °C and < 65 °C; and (iv) wherein the ethylene stream (3) in the preheater (4a) has a temperature (Te) of > 80 °C and < 100 °C; and (v) wherein the comonomer stream (5) comprising 2-hydroxy ethyl methacrylate, is injected into the first preheater (4a) at a concentration of > 0.01 wt.% and < 0.65 wt.%, with regard to the total weight of the ethylene feed stream (3); and wherein the ethylene copolymer consists of with regard to the24POLY0090-WO-ORD17total weight of the ethylene copolymer, of > 99.2 and < 99.7 wt.%, of polymeric units derived from ethylene; and > 0.3 and < 0.8 wt.% of polymeric units derived from 2-hydroxy ethyl methacrylate.

[0049] Preferably, the vinyl based monomer (D) is an acrylate based ionomer (IA) having any one of structure selected from:tBuAEM-AAMPSApreferably wherein the vinyl based monomer (D) is an acrylate based ionomer (IA) represented by the structure below and defined as MAMADAME:MAMADAME , where the ionomer MAMADAME is derived from methacrylic acid (MA) and dimethylaminoethyl methacrylic acid (MADAME).

[0050] In some embodiments of the invention, chain transfer agents such as propylene may be added to the ethylene stream prior to injecting the stream into the compressor. In another embodiment of the invention initiator compounds may for example be added in in the polymerization reactor.24POLY0090-WO-ORD18

[0051] Preferably wherein, wherein the reaction of the ethylene monomer with the vinyl based monomer (D) is carried out in presence of initiators wherein the initiator is introduced in the reactor (20) in an amount of > 0 ppm and < 300 ppm, preferably > 0 ppm and < 200 ppm, with regard to the total weight of the product stream (8); and wherein the initiator is selected from organic peroxides, azo based compounds and combinations thereof.

[0052] The polymerisation process may for example be performed in the presence of an initiator. Such initiator may for example be an initiator composition comprising one or more selected from organic peroxides or azo compounds. Suitable organic peroxides may for example include diacyl peroxides, dialkyl peroxides, peroxymonocarbonates, peroxydicarbonates, peroxyketals, peroxyesters, cyclic peroxides, hydroperoxides. Suitable azo compounds may for example include 2,2'-azodi(isobutyronitrile), 2,2'-azodi(2-methylbutyronitrile), 1,1'- azodi(hexahydrobenzonitrile).

[0053] In an embodiment, the free radical initiator composition may for example comprise 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butyl peroxypivalate and / or t-butyl peroxy benzoate. Such initiators may for example be fed to the tubular reactor in a pure form or as a solution in a solvent. As solvent, for example a C2-C20 normal paraffin or C2-C20 isoparaffin may be used. For example, such solution may comprise >2.0% and <65.0% by weight of initiator, alternatively >5.0% and <40.0% by weight, alternatively >10.0% and <30.0% by weight, compared to the total weight of the solution.

[0054] After finishing off the polymerization, and having applied multiple cooling steps, the reaction mixture is depressurized and / or cooled and separated in a high pressure separator (HPS). The high pressure separator separates the reaction mixture into an ethylene rich stream, containing minor amounts of waxes and / or entrained polymer, and a polymer rich stream, which is sent for further separation to the low pressure separator (LPS).

[0055] Ethylene stream is cooled down and cleaned in stream. Stream is a purge stream to remove impurities and / or inerts. The ethylene-based polymer separated in the LPS is further processed. The ethylene removed in the LPS is fed to the booster compressor, where during the compression condensable, like solvent, lubrication oil and other liquids, are collected and removed.24POLY0090-WO-ORD19System

[0056] In an aspect of the invention, the invention relates to a system for producing ethylene copolymer according to the process of the present invention, wherein the system comprises:(a) the compressor unit (2) configured to receive an ethylene feedstream (1);(b) the first preheater (4a) positioned downstream to the compressor unit (2) and in fluid communication with the compressor unit (2) and adapted to receive the ethylene stream (3);(c) the dosing line (12) configured to feed the comonomer stream (5) to the first preheater (4a), wherein the dosing line (12) is in fluid communication with the first preheater (4a) and with a pump (15) that is configured to supply the comonomer stream (5);(d) a second preheater (4b) positioned downstream to the first preheater (4a) and in fluid communication with the first preheater (4a) and adapted to receive the product stream (6); and(e) a reactor (20) positioned downstream to the second preheater (4b) and in fluid communication with the second preheater (4b) and adapted to receive the product stream (8); wherein the reactor (20) is configured to polymerize the ethylene monomer with the vinyl based monomer (D) to obtain the ethylene copolymer.

[0057] The invention will now be demonstrated with the following non-limiting examples.EXAMPLES

[0058] Purpose: To evaluate the process for the production of ethylene-HEMA based copolymer and whether the process of the present invention can be carried out by mixing the ethylene and the monomer 2-hydroxyethyl methacrylate (HEMA) while maintain any rise in temperature on mixing. To evaluate the success of the process parameters in accordance with the invention, experiments were conducted to observe whether the HEMA comonomer stream (5) at the point of contact with the ethylene stream would have a temperature not greater than 90 °C, a24POLY0090-WO-ORD20temperature indicative of high risks of acrylate self-polymerization, possible fouling and poor reaction kinetics.

[0059] Material and process conditions: The details of the materials are provided below:Table 1

[0060] Process Operation - The direct injection of the comonomer at the proper conditions allows the use of the comonomer without further dilution saving the compression installation and energy costs associated with extra volume of ethylene used, for cooling the HEMA stream to be injected. The HEMA comonomer stream was injected into the first preheater (4a) slightly above ambient pressures. The HEMA monomer stream (5) was injected at the center of the preheater (4a) at temperatures below ethylene stream. The injection of the HEMA was done using an injection device as described in the patent EP3565659B1, with the device comprising the annular part, a support structure, an injector part, and a supply channel. The monomer streams were mixed within the first meters after the injection.24POLY0090-WO-ORD21

[0061] Polymerization in the tubular reactor - In a high-pressure tubular reactor, ethylene copolymers were prepared by reacting a feed mixture comprising ethylene and the HEMA monomer. In addition, a quantity of 1.40 mol % of isopropanol with regard to the molar quantity of ethylene was fed.

[0062] The reaction was performed at a pressure of 200 MPa and at a temperature of 200- 210 °C. The reaction was initiated by addition of a 4.0 g / 1 solution of t-butyl peroxy pivalate (t- BPP) in heptane. The average residence time in the tubular reactor in all examples was 45 s. The obtained ethylene polymer was collected.

[0063] Samples IE1-IE6 are inventive examples where the HEMA monomer stream (5) was injected in the first preheater while samples CE1-CE6 are comparative examples where the HEMA monomer stream was injected in the second preheater (4b).

[0064] Table 2(a), shows the operating parameters when HEMA comonomer was injected in the first preheater (4a) where the ethylene stream had a temperature of 90 °C. The feedstream (5) containing HEMA monomer was maintained at 40 °C.Table 2 (a)

[0065] Table 2(b), shows the operating parameters when HEMA comonomer was injected in the first preheater (4a) where the ethylene stream was maintained at a temperature of 90 °C. The feedstream containing HEMA monomer was maintained at 60 °C.24POLY0090-WO-ORD22Table 2(b)

[0066] Table 3(a) shows the operating parameters when HEMA comonomer was injected in the second preheater (4b) where the ethylene stream was maintained a temperature of 135 °C. The high temperature of ethylene stream in the second preheater (4b) was specifically maintained for the stream to have a temperature closer to the polymerization reactor (135 °C). The feedstream (5) in the dosing line containing HEMA monomer was maintained at 40 °C prior to injection into the second preheater (4b).Table 3 (a)24POLY0090-WO-ORD23

[0067] Table 3(b) shows the operating parameters when HEMA comonomer stream (5) was injected in the second preheater (4b) where the ethylene stream has a temperature of 135 °C. The feedstream containing HEMA monomer was maintained at 60 °C.Table 3(b)

[0068] From Table 2(a) and 2(b), for each of IE1-IE3, it is evident that the HEMA comonomer stream upon contact with the ethylene stream, reaches a temperature, which is below the temperature of 90 °C or the stream temperature of ethylene feed stream.

[0069] For example, in IE1 the temperature at the point of contact of the HEMA stream (5) with the ethylene stream in the first preheater was recorded at 76.62 °C while for IE3 the temperature of stream (5) containing HEMA at the point of contact with the ethylene stream (3) in the first preheater (4a) had a temperature of 60.73 °C.

[0070] The temperature rise of the HEMA stream for each of the cases IE 1 and IE3 was around ~35 °C and ~ 20 °C respectively, which was significantly lower than when the feed stream with identical flow rates were introduced in the second preheater (CE4 and CE6). In other words,24POLY0090-WO-ORD24the temperature of stream (5) containing HEMA upon contact of ethylene with HEMA allowed excellent temperature management of the ethylene-HEMA copolymer process.

[0071] By limiting the temperature rise on mixing of the ethylene with the HEMA monomer, extensive cooling mechanism such as cooling by the use of heat exchangers or by an extensive array network of water jackets was avoided. Further, by limiting the temperature rise, the risks related to fouling in the preheater and risks related to self-polymerization of HEMA was significantly mitigated. It was further observed using thermal sensors and thermocouple, that no fouling or hot spots were observed for (IE1-IE6) and heat transfer between the ethylene stream media and the HEMA monomer stream was not impeded.

[0072] Moreover, from the data (IE1 versus CE1 or CE4) it is also evident that to synthesize ethylene -HEMA copolymer with low HEMA content while managing the temperature rise, it is particularly suitable to inject the HEMA monomer in the first preheater (4a) rather than in the second preheater (4b) on account of lower temperature rise. In other words when the flowrate of HEMA monomer is low, it is appropriate that the HEMA monomer is injected at the first preheater rather than in the second preheater. This conclusion is especially true as there is significant rise in temperature when HEMA monomer was injected into the second preheater at low flow rate as evidenced from the data under Table 3(a) and Table 3(b).

[0073] For example, as seen from the data of comparative example CE1, at a flow rate of 65 kg / hr, the temperature of the HEMA stream on contact with the ethylene stream was 107.98 °C with a temperature rise of the HEMA stream recorded at 67.98 °C. Such a significant rise in temperature is undesirable as it is expected that self-polymerization of HEMA would be initiated along with fouling in the preheater. Further at such high temperature, there is significant risk in the formation of hot spots and thermal runway reaction affecting polymerization kinetics and eventually affecting the production process of the ethylene copolymers.

[0074] Further by injecting the HEMA monomer stream in the first preheater (4a), the temperature rise was limited, and the use of further diluent for the HEMA monomer was avoided. The process of the present invention further allows the monomer to be introduced in the preheater with the ethylene stream at relatively low temperature for example at a temperature as low as 40 °C or 60 °C.24POLY0090-WO-ORD25

[0075] It was further observed that the ethylene copolymer for CE1, CE4, CE5 and CE6 had inconsistent properties with poor monomer incorporation when determined using13C NMR and / orJH NMR and had the ethylene copolymers was found to have large amounts of oligomer. This was on expected lines as shown in previous literature that at temperature from about 80 °C and above, acrylates tend to start self-polymerizing. On the other hand, IE1, IE2 IE3, IE5 and IE6 polymers were obtained with expected reaction kinetics and had reduced oligomer formation.

[0076] It is now demonstrated that the invention now provides a process to prepare ethylene copolymer such as ethylene-HEMA copolymers, while effectively managing the temperature rise on mixing of the ethylene with the HEMA monomer. The temperature management was achieved by injecting the vinyl monomer at a suitable location (first preheater 4(a)) in a two-preheater set up located upstream to the tubular reactor. As a further measure it was seen that the temperature rise was managed by controlling the flow rate of the monomer stream, temperature of the monomer stream and the temperature of the ethylene stream.

[0077] The content of recurring units derived from HEMA was determined via NMR, wherein the sample is dissolved in deuterated tetrachloroethane at 120° C. The NMR spectra is recorded with a Bruker Avance 500 NMR spectrometer equipped with a 10 mm diameter cryocooled probe head, operating at 125° C., to obtain both 'H-NMR and13C-NMR spectra, measuring time13C-NMR 3 hrs, 'H-NMR 30 min.

Claims

24POLY0090-WO-ORD26CLAIMS1. A process for preparing an ethylene copolymer, wherein the process comprises:(a) injecting an ethylene feed stream (1) into a compressor unit (2) to obtain an ethylene feed stream (3) comprising ethylene monomer, preferably wherein the ethylene feed stream (3) has a pressure of >180 MPa and < 320 MPa;(b) feeding at least a portion of the ethylene feed stream (3) into a first preheater (4a) positioned downstream to the compressor unit (2);(c) feeding a comonomer stream (5) comprising a vinyl monomer (D) into the first preheater (4a) such that the comonomer stream (5) is supplied to the first preheater (4a) by means of a dosing line (12) that is in fluid communication with the first preheater (4a);(d) contacting the ethylene feed stream (3) and the comonomer stream (5) and subsequently mixing the streams to obtain a product stream (6);(e) feeding at least a portion of the product stream (6) into a second preheater (4b) to obtain a product stream (8);(f) feeding the product stream (8) into a reactor (20) positioned downstream to the second preheater (4b) and polymerizing the ethylene monomer and the vinyl monomer (D) to obtain the ethylene copolymer; and• wherein the comonomer stream (5) comprising a vinyl monomer (D) is injected into the first preheater (4a) at a flow rate of > 20 and < 2500 kg / hr, preferably > 20 and < 1000 kg / hr, preferably > 50 and < 1000 kg / hr, preferably > 50 and < 500 kg / hr, preferably > 60 and < 300 kg / hr; and• wherein the temperature (Th) of the comonomer stream (5) in the dosing line (12) prior to injecting into the first preheater (4a) ranges from > 30 °C and < 80 °C, preferably > 30 °C and < 70 °C; and• wherein the comonomer stream (5) on contacting with the ethylene feed stream (3) has a temperature of > 55 °C and < 90 °C, preferably > 60 °C and < 90 °C, preferably > 60 °C and < 82 °C, preferably > 60 °C and < 78 °C.24POLY0090-WO-ORD272. The process of claim 1, wherein the comonomer stream (5) comprising the vinyl monomer (D), is injected into the first preheater (4a) at a flow rate of > 50 and < 1000 kg / hr, preferably > 50 and < 500 kg / hr, preferably > 60 and < 300 kg / hr, preferably > 60 and < 75 kg / hr.

3. The process according to any one of claims 1-2, wherein the comonomer stream (5) comprising the vinyl monomer (D), is injected into the first preheater (4a) at a concentration of > 0.01 wt.% and < 0.65 wt.%, preferably > 0.05 wt.% and < 0.65 wt.%, preferably > 0.1 wt.% and < 0.6 wt.%, with regard to the total weight of the ethylene feed stream (3).

4. The process according to any one of claims 1-3, wherein the first preheater (4a) is operated at a temperature of > 80 °C and < 120 °C, preferably > 80 °C and < 100 °C and the second preheater (4b) is operated at a temperature of > 110 °C and < 170 °C, preferably > 120 °C and < 140 °C, preferably > 125 °C and < 140 °C.

5. The process according to any one of claims 1-4, wherein the temperature (Th) of the comonomer stream (5) in the dosing line (12) prior to injecting into the first preheater (4a) ranges from > 35 °C and < 65 °C, preferably > 40 °C and < 65 °C.

6. The process according to any one of claims 1-5, wherein the ethylene copolymer comprises or consists of, with regard to the total weight of the ethylene copolymer of: (i) > 94.0 and < 99.9 wt.%, preferably > 96.0 and < 99.7 wt.%, preferably > 97.0 and < 99.7 wt.%, of polymeric units derived from ethylene; and(ii) > 0.1 and < 6.0 wt.%, preferably > 0.3 and < 4.0 wt.%, preferably > 0.3 and <3.0 wt.% of polymeric units derived from the vinyl based monomer (D); andpreferably wherein the ethylene copolymer consists of with regard to the total weight of the ethylene copolymer, of > 96.0 and < 99.7 wt.%, of polymeric units derived from ethylene; and > 0.3 and < 4.0 wt.% of polymeric units derived from the vinyl-based monomer (D), preferably wherein the content of ethylene and vinyl based monomer (D) is determined using13C NMR and / or24POLY0090-WO-ORD28JH NMR, preferably wherein the ethylene copolymer consists of with regard to the total weight of the ethylene copolymer, of > 99.0 and < 99.7 wt.%, of polymeric units derived from ethylene; and > 0.3 and < 1.0 wt.% of polymeric units derived from the vinyl-based monomer (D), most preferably wherein the ethylene copolymer consists of with regard to the total weight of the ethylene copolymer, of > 99.2 and < 99.7 wt.%, of polymeric units derived from ethylene; and > 0.3 and < 0.8 wt.% of polymeric units derived from the vinyl-based monomer (D).

7. The process according to any one of claims 1-6, wherein the ethylene stream (3) is fed to the first preheater (4a) at a flow rate of > 50 and < 120 tons / hour, preferably > 60 and < 100 tons / hour; and / or wherein the ethylene stream (3) in the first preheater (4a) has a temperature (Te) of > 80 °C and < 100 °C.

8. The process according to any one of claims 1-7, wherein the reaction of the ethylene monomer with the vinyl monomer (D) is carried out in the reactor (20) at any pressure of >180 MPa and <350 MPa, preferably > 200 MPa and < 300 MPa and at any temperature of >100 °C and < 350 °C, preferably >125 °C and <310 °C, preferably >130 °C and < 300 °C; and / or wherein the reactor (20) is a tubular reactor.

9. The process according to any one of claims 1-8, (i) wherein the comonomer stream (5) comprising the vinyl monomer (D) is injected into the first preheater (4a) at a flow rate of > 60 and < 1000 kg / hr, preferably > 60 and < 300 kg / hr, preferably > 60 and < 75 kg / hr; and (ii) the comonomer stream (5) on contacting with the ethylene feed stream (3) has a temperature of > 60 °C and < 90 °C; (iii) the temperature (Th) of the comonomer stream (5) in the dosing line (12) and prior to injecting into the first preheater (4a) ranges from > 35 °C and < 65 °C; and (iv) wherein the ethylene stream (3) in the preheater (4a) has a temperature (Te) of > 80 °C and < 100 °C; and (v) wherein the comonomer stream (5) comprising the vinyl monomer (D), is injected into the first preheater (4a) at a concentration of > 0.01 wt.% and < 0.65 wt.%, preferably > 0.05 wt.% and < 0.65 wt.%, preferably > 0.1 wt.% and < 0.6 wt.%, with regard to the total weight of the ethylene feedPOLY0090-WO-ORD29stream (3); and wherein the ethylene copolymer comprises with regard to the total weight of the ethylene copolymer of > 96.0 and < 99.7 wt.%, of polymeric units derived from ethylene; and > 0.3 and < 4.0 wt.% of polymeric units derived from the vinyl based monomer (D), most preferably wherein the ethylene copolymer consists of with regard to the total weight of the ethylene copolymer, of > 99.2 and < 99.7 wt.%, of polymeric units derived from ethylene; and > 0.3 and <0.8 wt.% of polymeric units derived from the vinylbased monomer (D).

10. The process according to any one of claims 1-9, wherein the vinyl based monomer (D) is an acrylate based monomer (A) or an acrylate based ionomer (IA), preferably wherein the vinyl based monomer (D) is an acrylate based monomer (A).

11. The process according to any one claims 1-10, wherein the vinyl based monomer (D) is an acrylate based monomer (A) selected from the group consisting of 2-hydroxy ethyl acrylate, 2-hydroxy ethyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 2- hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2,3 -dihydroxypropyl acrylate, 2,3- dihydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, polypropylene glycol) monoacrylate, poly(propyleneglycol) monomethacrylate, poly(ethylene glycol) monoacrylate, poly(ethylene glycol) monomethacrylate, poly(ethylenepropyleneglycol) monomethacrylate and 2-hydroxy ethyl vinyl ether, 1,4- butanediol dimethacrylate, hexanediol dimethacrylate, ethylene glycol dimethacrylate, 1,3- butylene glycol dimethacrylate, dodecanediol dimethacrylate, glycerol dimethacrylate, 1,4-butanediol diacrylate, hexanediol diacrylate, ethylene glycol diacrylate, 1,3 -butylene glycol diacrylate, dodecanediol diacrylate, glycerol diacrylate, glycerol 1,3-diglycerolate diacrylate, glycerol 1,3-diglycerolate dimethacrylate, poly(ethylene glycol) dimethacrylate, polypropylene glycol) dimethacrylate, poly(ethylenepropyleneglycol) dimethacrylate, 1,4-butanediol divinyl ether, poly thylene glycol) divinyl ether, di(ethyleneglycol) divinyl ether, 1,5-hexadiene, 1,7-octadiene, 1,9-decadiene and 1,13- tetradecadiene, preferably wherein the vinyl based monomer (D) is an acrylate based monomer (A) selected from 2-hydroxy ethyl methacrylate, 1,4-butanediol dimethacrylatePOLY0090-WO-ORD30and combinations thereof, preferably wherein the acrylate monomer is 2-hydroxyethyl methacrylate.

12. The process according to any one of claims 1-11, (i) wherein the comonomer stream (5) comprising 2-hydroxyethyl methacrylate is injected into the first preheater (4a) at a flow rate of > 60 and < 1000 kg / hr, preferably > 60 and < 300 kg / hr; and (ii) the comonomer stream (5) on contacting with the ethylene feed stream (3) has a temperature of > 60 °C and < 90 °C; and (iii) the temperature (Th) of the comonomer stream (5) in the dosing line (12) and prior to injecting into the first preheater (4a) ranges from > 35 °C and < 65 °C; and (iv) wherein the ethylene stream (3) in the preheater (4a) has a temperature (Te) of > 80 °C and < 100 °C; and (v) wherein the comonomer stream (5) comprising 2-hydroxyethyl methacrylate, is injected into the first preheater (4a) at a concentration of > 0.01 wt.% and < 0.65 wt.%, preferably > 0.05 wt.% and < 0.65 wt.%, preferably > 0.1 wt.% and < 0.6 wt.%, with regard to the total weight of the ethylene feed stream (3); and wherein the ethylene copolymer comprises with regard to the total weight of the ethylene copolymer of > 96.0 and < 99.7 wt.%, of polymeric units derived from ethylene; and > 0.3 and < 4.0 wt.% of polymeric units derived from 2-hydroxyethyl methacrylate.

13. The process according to any one of claims 1-12, wherein the comonomer stream (5) comprising the vinyl monomer (D) is injected into the first preheater (4a) at a flow rate of > 60 and < 300 kg / hr, preferably > 60 and < 75 kg / hr; and (ii) the comonomer stream (5) on contacting with the ethylene feed stream (3) has a temperature of > 60 °C and < 90 °C; (iii) the temperature (Th) of the comonomer stream (5) in the dosing line (12) and prior to injecting into the first preheater (4a) ranges from > 35 °C and < 65 °C; and (iv) wherein the ethylene stream (3) in the preheater (4a) has a temperature (Te) of > 80 °C and < 100 °C; and (v) wherein the comonomer stream (5) comprising 2-hydroxyethyl methacrylate, is injected into the first preheater (4a) at a concentration of > 0.01 wt.% and < 0.65 wt.%, preferably > 0.05 wt.% and < 0.65 wt.%, preferably > 0.1 wt.% and <0.6 wt.%, with regard to the total weight of the ethylene feed stream (3); and wherein the ethylene copolymer consists of with regard to the total weight of the ethylene copolymer, of > 99.2 and < 99.7POLY0090-WO-ORD31wt.%, of polymeric units derived from ethylene; and > 0.3 and < 0.8 wt.% of polymeric units derived from 2 -hydroxy ethyl methacrylate.

14. The process according to anyone claims 1-10, wherein the vinyl based monomer (D) is an acrylate based ionomer (IA) having any one of structure selected from:tBuAEM-AAMPSApreferably wherein the vinyl based monomer (D) is an acrylate based ionomer (IA) represented by the structure below and defined as MAMADAME:MAMADAME , where the ionomer MAMADAME is derived from methacrylic acid (MA) and dimethylaminoethyl methacrylic acid (MADAME).

15. A system for producing ethylene copolymer according to the process as claimed in any one of claims 1-14, wherein the system comprises:(a) the compressor unit (2) configured to receive an ethylene feedstream (1);POLY0090-WO-ORD32(b) the first preheater (4a) positioned downstream to the compressor unit (2) and in fluid communication with the compressor unit (2) and adapted to receive the ethylene stream (3);(c) the dosing line (12) configured to feed the comonomer stream (5) to the first preheater (4a), wherein the dosing line (12) is in fluid communication with the first preheater (4a) and with a pump (15) that is configured to supply the comonomer stream (5);(d) a second preheater (4b) positioned downstream to the first preheater (4a) and in fluid communication with the first preheater (4a) and adapted to receive the product stream (6); and(e) a reactor (20) positioned downstream to the second preheater (4b) and in fluid communication with the second preheater (4b) and adapted to receive the product stream (8); wherein the reactor (20) is configured to polymerize the ethylene monomer with the vinyl based monomer (D) to obtain the ethylene copolymer.

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