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Regulation and control method and synthesis method for EVA synthesis with controllable branching degree, EVOH resin and synthesis method thereof

A synthesis method and technology of branching degree, applied in the field of EVA and EVOH resin synthesis, can solve the problems of low molecular weight, difficult to control the uniformity of distribution, and poor linear controllability of polymer structure.

Active Publication Date: 2021-09-10
CHANGCHUN INST OF APPLIED CHEMISTRY - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The ethylene content in EVOH is easy to control, and there have been many reports, but the distribution and branching degree of ethylene segments are not easy to control. Correspondingly, the linear controllability of the polymer structure is poor, and the uniformity of the distribution of hydroxyl groups on the main chain is difficult to control. , or the hydroxyl group appears on the side chain, at the same time, the crystallinity of some polymers is difficult to control, and the distribution of crystal regions is uneven
High degree of branching or uncontrollable branching of the polymer leads to poor linear structure and low molecular weight of the polymer, which affects the crystallization properties of the polymer (including the distribution of crystallization regions), and eventually leads to low molecular weight of EVOH, unstable batches, and controllable structure poor sex

Method used

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  • Regulation and control method and synthesis method for EVA synthesis with controllable branching degree, EVOH resin and synthesis method thereof
  • Regulation and control method and synthesis method for EVA synthesis with controllable branching degree, EVOH resin and synthesis method thereof
  • Regulation and control method and synthesis method for EVA synthesis with controllable branching degree, EVOH resin and synthesis method thereof

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preparation example Construction

[0099] The present invention provides a kind of synthetic method based on the EVA of the control method described in any one of the above-mentioned technical schemes, comprising the following steps:

[0100] 1`) Vinyl acetate, initiator, solvent, and ethylene are added to the reaction device, the pressure of the reaction is regulated, and polymerization is carried out to obtain EVA;

[0101] Wherein, the addition method of solvent comprises one or more of adding separately, solution of ethylene and solvent, solution of vinyl acetate and solvent, and solution of initiator and solvent;

[0102] The raw material of described EVA synthesis comprises ethylene, vinyl acetate, initiator and solvent.

[0103] In the present invention, the synthetic raw materials are industrial-grade raw materials.

[0104] In the present invention, the pressure of the polymerization reaction is preferably the pressure of the mixed gas of ethylene gas and protective gas. Alternatively, the pressure o...

Embodiment 1

[0152] Check the airtightness of a 500ml stainless steel autoclave with PTFE lining, heat up to 100°C for 30 minutes, replace with nitrogen for 5 times, and then replace with ethylene gas for 5 times. After the reaction kettle is cooled below 40°C, add 60ml of vinyl acetate, and then add the initiator azobisisobutyronitrile and 35ml of methanol / cyclohexane mixed solution (mixing volume ratio is 3 / 1) into the reaction kettle to control the temperature of the initiator. The concentration is 5.6×10 -3 mol / L; fill in 3.2MPa ethylene while stirring, then fill in nitrogen, adjust the pressure of the reaction system to 10MPa, after the temperature rises to 75°C, continuously fill in ethylene to keep the pressure of the reaction system stable, react for 5 hours, cool to room temperature, and vent Pressure, the product is transferred to a vacuum oven, and dried at 65°C to obtain EVA, the ethylene content is 32% (NMR, mol), and the hydrogen nuclear magnetic spectrum is as follows: Ima...

Embodiment 2

[0159] Check the airtightness of a 500ml stainless steel autoclave with PTFE lining, heat up to 100°C for 30 minutes, replace with nitrogen for 5 times, and then replace with ethylene gas for 5 times. After the reaction kettle is cooled below 40°C, add 70ml of vinyl acetate, then mix the initiator azobisisobutyronitrile and benzoyl peroxide with 25ml of methanol and add to the reaction kettle to control the temperature of azobisisobutyronitrile and benzoyl peroxide. The concentration of formyl was 5.6×10 -3 mol / L and 2.3×10 -3 mol / L; fill in 4.0MPa ethylene while stirring, after heating up to 80°C, keep filling ethylene to keep the pressure of the reaction system stable, react for 3h, cool to room temperature, release the pressure, transfer the product to a vacuum oven, and bake at 65°C Drying gave EVA with an ethylene content of 38% (NMR, mol).

[0160] Dissolve EVA in 200ml methanol (EVA concentration is 25wt%), heat up to 70°C, after the reaction temperature is stable, di...

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Abstract

The invention provides EVOH resin. The weight-average molecular weight of the EVOH resin is greater than or equal to 9 kg / mol. The molecular weight distribution PDI of the EVOH resin is less than 2.0. Based on the response relationship between the reaction pressure and the polymer structure, the invention provides the method for regulating, controlling and synthesizing the EVA with the controllable branching degree according to the difference of solubility, partition coefficient and initiation efficiency of different initiators in different solvent systems, and the method is realized by compounding an initiator, compounding a solvent and regulating the reaction pressure, and has the characteristics of strong controllability, mild conditions, simple operation and large-scale synthesis prospects. EVOH resin with high molecular weight and narrow distribution can be obtained through alcoholysis reaction of the EVA prepared by the method.

Description

technical field [0001] The invention belongs to the technical field of EVA and EVOH resin synthesis, and relates to a control method and a synthesis method for EVA synthesis, an EVOH resin and a synthesis method thereof, in particular to a control method and a synthesis method for EVA synthesis with controllable branching degree , an EVOH resin and a synthesis method thereof. Background technique [0002] EVOH (ethylene-vinyl alcohol copolymer) is a semi-crystalline polymer material with excellent gas (such as oxygen, carbon dioxide, etc.) barrier properties and processing properties, and is widely used in the packaging industry, such as food packaging bags. Industrially, EVOH is synthesized using ethylene and vinyl acetate as raw materials. First, EVA is prepared by free radical-induced solution polymerization, and EVOH is obtained in alcoholysis. Nanjing Institute of Forestry and Chemical Industry carried out the synthesis of EVOH (Forest Chemical Industry Communication, ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08F210/02C08F218/08C08F2/38C08F2/06C08F8/00
CPCC08F210/02C08F2/38C08F2/06C08F8/00C08F218/08
Inventor 白晨曦祁彦龙代全权崔龙
Owner CHANGCHUN INST OF APPLIED CHEMISTRY - CHINESE ACAD OF SCI
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