A composition containing ethylene-vinyl alcohol copolymer and its preparation method
A vinyl alcohol copolymer and vinyl acetate copolymerization technology, applied in the field of compositions containing ethylene-vinyl alcohol copolymer, can solve the problems of reducing the gas barrier property of the polymer, decreasing the melt processing stability, and deteriorating the quality of the polymer, etc. Overcome the effects of poor reusability, high product quality, and improved high temperature colorability
Active Publication Date: 2016-11-30
CHINA PETROCHEMICAL CORP +1
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Problems solved by technology
Ethylene-vinyl alcohol copolymers have both the processability of polyethylene and the high barrier properties of vinyl alcohol polymers, but in order to ensure sufficient gas barrier properties, EVOH usually contains vinyl alcohol structures, and vinyl alcohol polymers Due to the existence of a large number of hydroxyl groups, the crystallinity is high, and the melting point is high, close to the decomposition temperature, so the dehydration of hydroxyl groups is easy to occur during melt processing, which will deteriorate the quality of the polymer.
The increase of the vinyl alcohol unit content can increase the macromolecular force and improve the barrier property, but its melt processing stability decreases. Although the melt processability can be improved to a certain extent by adding some additives afterward, the external additives have a certain effect. To a certain extent, the gas barrier properties of the polymer will inevitably be reduced, and it will migrate to the surface with time, causing certain pollution
Method used
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Embodiment 1
[0035] A preparation method of a composition containing ethylene-vinyl alcohol copolymer, as follows:
[0036] 1), initial feeding
[0037] Add 75 parts of vinyl acetate monomer, 45 parts of methanol and ethanol (90%:10%) mixed solvent, and 0.0007 part of azobisisobutyronitrile into the stainless steel reaction kettle.
[0038] 2), replacement in the kettle
[0039] Inject 8-12 bar of N2 at room temperature to replace and remove oxygen from the initial mixture twice, each time for 5 minutes; then introduce 8-12 bar of ethylene gas to replace and remove nitrogen from the initial mixture twice; 5min.
[0040] 3), polymerization reaction
[0041] Feed ethylene gas, control the pressure in the kettle to be 40kg / cm 2 , when the temperature reaches 95°C, start timing, stop the reaction after 8 hours, close the ethylene inlet valve, cool down to below 40°C, release the pressure and discharge to obtain the polymerized ethylene-vinyl acetate copolymer.
[0042] 4) Blowing off resi...
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Abstract
The invention relates to a composition containing ethylene-vinyl alcohol copolymer and a preparation method thereof, comprising 90-95% ethylene-vinyl alcohol copolymer and 5-10% ethylene-vinyl alcohol small molecule oligomerization in weight percentage The molecular structure of the ethylene-vinyl alcohol copolymer contains 1-2% mol of 1,2-ethylene glycol structure. The preparation method of the composition is to mix 50-80 parts of vinyl acetate monomer, 20-50 parts of alcohol solvent, and 0.0001-0.001 part of initiator at a temperature of 80-140°C and a pressure of 30-70kg / cm 2 Polymerized at the bottom and obtained by saponification reaction, the molecular structure contains 1-2 (mol)% 1,2-ethylene glycol structure that reduces viscosity, and 5-10% small molecule oligomerization that acts as plasticizer It is more conducive to the melt processability of ethylene-vinyl alcohol copolymers, and overcomes the problems of poor reusability of conventional ethylene-vinyl alcohol copolymers, and the problem that the inorganic salt additives contained are easy to migrate to the surface of the polymer and pollute the environment. The preparation method of the invention has the advantages of simple process, safety and environmental protection, high product quality, and is suitable for industrialized production.
Description
technical field [0001] The present invention relates to a composition containing ethylene-vinyl alcohol copolymer, in particular to a composition containing ethylene-vinyl alcohol copolymer with improved melting processability and a preparation method thereof. Background technique [0002] Ethylene-vinyl alcohol copolymer (EVOH) is a crystalline polymer with a chain molecular structure. Its properties mainly depend on the mole fraction of comonomers, and its gas barrier properties, moisture barrier properties and processing properties change with the ethylene content. When the ethylene content increases, the gas barrier properties decrease, the moisture resistance performance improves, and the resin is easier to process . If the ethylene content is less than 20%, stable melt processability cannot be guaranteed, and if the ethylene content is greater than 50%, the gas barrier properties will be severely damaged. Therefore, the ethylene content in EVOH is generally kept betwe...
Claims
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IPC IPC(8): C08F218/08C08F210/02C08F8/12C08L29/04C08K5/053
Inventor 窦玉芹金立维任文革朱永年李永江储富祥彭达平吴刚易兰千
Owner CHINA PETROCHEMICAL CORP