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Method for preparing EVA (ethylene-vinyl acetate) emulsion by sectioning and pressurizing ethylene

A technology of segmented pressurization and ethylene, applied in the field of ethylene segmental pressurization to prepare EVA emulsion, can solve problems such as poor performance, high Tg, limited product application range, etc., achieve moderate Tg, improve reaction rate, and high industrial application. effect of value

Active Publication Date: 2017-03-29
CHINA PETROLEUM & CHEM CORP +1
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The above products have high Tg and poor performance, which greatly limits the scope of application of the products

Method used

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  • Method for preparing EVA (ethylene-vinyl acetate) emulsion by sectioning and pressurizing ethylene
  • Method for preparing EVA (ethylene-vinyl acetate) emulsion by sectioning and pressurizing ethylene

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preparation example Construction

[0038] Such as figure 1 The shown copolymerization reaction device of preparing EVA emulsion. A single-pot batch operation is adopted, including a copolymerization reactor 1, a feeding mechanism and a product post-treatment part. The top of the copolymerization reactor 1 is provided with a surfactant, an initiator, a pH regulator and a vinyl acetate liquid-phase feed inlet, and N 2 and ethylene feed port. The colloid protective agent / surfactant tank 2 is communicated with the copolymerization reactor 1 through the high-pressure metering pump 6-2, the initiator tank 3 is communicated with the copolymerization reactor 1 through the high-pressure metering pump 6-3, and the pH regulator tank 4-1 is communicated with the copolymerization reactor 1 through the high-pressure metering pump 6-3. The metering pump 6-4 communicates with the copolymerization reactor 1, and the VAc monomer tank 5 communicates with the copolymerization reactor 1 through the high-pressure metering pump 6-5...

Embodiment 1

[0044] O / W emulsion polymerization system, select water-soluble initiator azobisisobutyromidine hydrochloride, the total consumption is 0.5wt% of vinyl acetate; initiator is azobisisobutyronitrile, consumption is 0.5wt% of vinyl acetate wt%; the amount of surfactant OP-10 is 15.0wt% of the amount of monomer VAc; the amount of pH regulator sodium bicarbonate is 0.75wt% of the amount of monomer VAc, and the pH of the control system is 6.5; the consumption of colloidal protective agent polyvinyl alcohol The amount is 1.53wt% of the amount of monomer VAc used. The polymerization reaction temperature is 65°C, and the reaction time is 5.0h.

[0045] The ethylene reaction pressure in the monomer dispersion stage was 4.0MPa; the ethylene reaction pressure in the latex particle formation stage was 5.0MPa; the ethylene reaction pressure in the latex particle growth stage was maintained at 6.0MPa; the ethylene reaction pressure in the polymerization end stage was maintained at 5.5MPa. U...

Embodiment 2

[0047] The ethylene reaction pressure in the monomer dispersion stage is 5.0MPa; the ethylene reaction pressure in the latex particle generation stage is 6.0MPa; the ethylene reaction pressure in the latex particle growth stage is maintained at 7.0MPa; the ethylene reaction pressure in the polymerization reaction end stage is maintained at 6.5MPa, and other reaction conditions With embodiment 1. Under these conditions, the Tg of the polymerization product is about 19°C, the VAc content is 61.7wt%, and the appearance characteristics of the elastomer are obvious.

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Abstract

The invention relates to a method for preparing EVA (ethylene-vinyl acetate) emulsion by sectioning and pressurizing ethylene. According to the method, emulsion copolymerization reaction of VAc (vinyl acetate copolymer) includes four stages, ethylene is led at the first monomer dispersion stage, the pressure of the led ethylene is increased but lower than preset reaction pressure at the second generation stage of emulsion particles, the pressure of the led ethylene is increased to the preset reaction pressure at the third growth stage of the emulsion particles, and the pressure of the led ethylene is reduced and lower than the preset reaction pressure at the fourth finishing stage of the copolymerization reaction. According to the growth process of the emulsion particles, the pressure of the ethylene is controlled step by step according to low, medium, high and medium, the copolymerization reaction can be more accurately and effectively controlled, chain transfer is stopped, tacticity of macromolecular chains of copolymers is adjusted, EVA emulsion products with wide Tg variation ranges are prepared, different production requirements are met, and the EVA emulsion products have high industrial application values.

Description

technical field [0001] The invention relates to a method for preparing EVA emulsion by stepwise pressurizing ethylene. Background technique [0002] Ethylene-vinyl acetate copolymer (EVA) is made from non-polar, crystalline ethylene monomer (E) and non-crystalline vinyl acetate monomer (VAc) as reactants through free radical initiated copolymerization. The production process originates from in high pressure polyethylene. The so-called EVA products mainly include EVA resin and EVA elastomer. Among them, EVA resin is mostly produced by improved LDPE process, with a VAc content of 5.0-40.0wt%; EVA elastomer is mostly produced by medium-pressure solution polymerization, with a VAc content of 40.0-70.0wt%. The new product that appears at present is EVA emulsion, wherein VAc content is 70.0-95.0wt%, is a kind of adhesive with excellent performance, nontoxic and tasteless, production cost is low, all has excellent bonding effect to the surface of many different materials. Its ap...

Claims

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Application Information

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IPC IPC(8): C08F218/08C08F210/02C08F2/30
Inventor 陈博于鲁强刘小萌刘金伟
Owner CHINA PETROLEUM & CHEM CORP
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