EVA Copolymer Solution Polymerization Low Pressure
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Solution Overview
Problem
Current methods for producing EVA copolymers with high ethylene content under low to medium pressure and low temperature are not mature, limiting their application and increasing production costs due to high equipment and energy consumption.
Innovation Solution
A method involving solution polymerization of ethylene and vinyl acetate in a reactor under low to medium pressure, with controlled pressure and temperature conditions, and the use of free radical initiators to achieve an EVA copolymer with ethylene content greater than 50wt%, applicable to fields requiring high ethylene content EVA.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-pressure and high-temperature bulk free radical polymerization is used to produce EVA copolymer, then the ethylene content can reach 5-40% by mole, but the capital costs and energy consumption are very high
Solution Approach 1:
The patent changes the polymerization parameters from high-pressure/high-temperature conditions to low-to-medium pressure (1-10 MPa) and low temperature (35-75°C) conditions. This is achieved by using solution polymerization with specific solvents (alcohols, esters, ketones, or their mixtures) and controlling the vinyl acetate to ethylene mass ratio between 1:1 to 1:20, which fundamentally alters the reaction conditions to reduce energy consumption while maintaining ethylene incorporation above 50wt%
Solution Approach 2:
The patent introduces a solvent as an intermediary medium to enable the polymerization reaction under milder conditions. The solvent (such as methanol, ethanol, propanol, butanol, esters like ethyl acetate, or ketones like acetone) acts as a heat transfer medium and reaction medium, allowing the free radical polymerization to proceed at low temperature and pressure, thereby reducing energy consumption while achieving high ethylene content
2Ease of manufacture
If solution polymerization under low to medium pressure is used to reduce equipment investment, then the ethylene content incorporated in EVA remains below 40wt%, which is not applicable to EVA copolymer fields
Solution Approach 1:
The patent optimizes the vinyl acetate to ethylene mass ratio to between 1:1 to 1:20, which is a critical parameter change that enables high ethylene incorporation (>50wt%) under low-to-medium pressure solution polymerization. This ratio control, combined with temperature control (35-75°C) and pressure control (1-10 MPa), fundamentally changes the polymerization outcome to achieve both low equipment investment and high ethylene content suitable for EVA applications
Solution Approach 2:
The patent replicates the beneficial effects of high-pressure bulk polymerization (high ethylene content and applicable properties) through a different process pathway - solution polymerization at low-to-medium pressure. By copying the essential outcome (high ethylene incorporation) through alternative means (solution process with controlled ratios and conditions), the patent achieves the same applicability without requiring high-pressure equipment
3Quantity of substance
If conventional bulk polymerization at high temperature and high pressure is used, then EVA copolymer with high ethylene content is obtained, but the equipment investment and operational costs are very high
Solution Approach 1:
The patent fundamentally changes the pressure parameter from high pressure (1,000-3,000 bar) to low-to-medium pressure (1-10 MPa), and temperature from high temperature (150-200°C) to low temperature (35-75°C). These parameter changes enable the use of simpler, less expensive equipment while achieving the same high ethylene content (>50wt%) through solution polymerization with controlled monomer ratios
Solution Approach 2:
The patent uses a solvent as an intermediary to enable the polymerization reaction under milder conditions. The solvent system (alcohols, esters, ketones, or their mixtures) allows the reaction to proceed at low pressure and temperature, eliminating the need for expensive high-pressure equipment while maintaining high ethylene incorporation through proper control of the vinyl acetate to ethylene ratio
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method produces EVA copolymers with properties equivalent to those made at high temperature and high pressure, while significantly reducing equipment investment and energy consumption, making them suitable for various industrial applications.
Implementation Method 1
Ethylene and vinyl acetate can produce copolymers having different properties in different production processes. In a conventional production process of EVA, a high-pressure and high-temperature polymerization device for the production of LDPE is utilized to carry out bulk free radical polymerization
Data Source
AI summary
The invention provides a method for preparing an EVA copolymer with a high ethylene content by solution polymerization under a low to a medium pressure, and belongs to the technical field of organic macromolecular compounds. The method comprises the following steps: initiating with a free radical initiator(s), a copolymerization reaction between ethylene and vinyl acetate in a solvent in a reactor under a low to a medium pressure to obtain the EVA copolymer; and continuing to add ethylene during the reaction to maintain the low to medium pressure, wherein the low to medium pressure is 1-101 MPa, and a ratio of a mass of the vinyl acetate to a mass of the initially added ethylene is (1:1) to (1:20). The amount of ethylene incorporated in the EVA copolymer prepared according to the method is ≥ 50wt%, and the EVA copolymer has properties equivalent to those of an EVA copolymer obtained by bulk polymerization at high temperature under high pressure, and is applicable to application fields to which the EVA copolymer prepared with a conventional method is applicable. Meanwhile, compared with the conventional method for preparing the EVA copolymer at high temperature under high pressure, the method according to the invention also greatly reduces the equipment investment and the high energy-consumption cost during production.