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Method for preparing acrylic acid-grafted polypropylene by supercritical carbon dioxide

A technology of acrylic acid grafting and carbon dioxide, which is applied in the production of bulk chemicals, textiles and papermaking, fiber treatment, etc., can solve the limitations of the application field of acrylic acid grafted polypropylene, it is difficult to meet the application of adhesives and compatibilizers, and there is no need to consider crosslinking problems and other problems, achieve broad industrial application prospects, improve grafting rate and selectivity, and achieve the effects of solvent-free recovery

Inactive Publication Date: 2009-03-18
XIANGTAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Chinese patent application No. 03141828.7 discloses a method for preparing unsaturated organic acid grafted polypropylene using a supercritical carbon dioxide medium. The unsaturated organic acid is acrylic acid or maleic anhydride, adding auxiliary monomers and initiators, and the grafting rate of acrylic acid In general, it can reach more than 5.5%, but the auxiliary monomer styrene must be used, which has high cost, high toxicity and serious environmental pollution.
[0008] Although both acrylic acid and maleic anhydride can be used as grafting monomers, maleic anhydride itself is grafted with short-chain branches or single molecules, so the probability of cross-linking reaction is very low, and there is no need to consider cross-linking problems during the reaction process; Acrylic acid is a graft monomer that is easy to self-polymerize and cross-link. As the grafting reaction continues, the cross-linking reaction of acrylic acid causes linear polypropylene to become a bulk polymer, and when the cross-linking reaches a certain After a certain degree, the acrylic acid grafted polypropylene (PP-g-AA) is neither soluble nor easy to melt. At this time, the material properties have undergone qualitative changes, and it is difficult to meet its adhesive and compatibilizer applications.
Gel rate (G gel %) is an important indicator for measuring the degree of cross-linking reaction, and the high gel rate undoubtedly limits the application of acrylic acid grafted polypropylene (PP-g-AA) as a compatibilizer
According to literature reports, except that the grafting rate prepared by the melt grafting method is low and no cross-linked products are seen; while other processes can obtain a higher grafting rate, but because the factors of the cross-linking reaction in the graft are not considered, the The prepared acrylic-grafted polypropylene does not work well as a compatibilizer and adhesive

Method used

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  • Method for preparing acrylic acid-grafted polypropylene by supercritical carbon dioxide
  • Method for preparing acrylic acid-grafted polypropylene by supercritical carbon dioxide
  • Method for preparing acrylic acid-grafted polypropylene by supercritical carbon dioxide

Examples

Experimental program
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Effect test

Embodiment 1

[0058] Use polypropylene granules, DCP and AA as raw materials, add them into a stainless steel high-pressure reactor equipped with stirring and pressure sensors at a weight ratio of PP / AA / DCP=100 / 10.5 / 0.5, and use CO 2 After the air in the kettle was purged clean, an appropriate amount of CO was introduced. 2 ; Swell at 80°C and 10.8MPa for 1 hour; then, heat up to 140°C, corresponding to a pressure of 15MPa, at this time, DCP thermally decomposes to initiate a free radical grafting reaction; after 4 hours of reaction, the CO in the kettle 2 Empty and take out the crude product of the graft PP-g-AA; finally, the crude product is extracted with absolute ethanol and degelated to obtain purified PP-g-AA.

[0059] The samples of blank PP, PP-g-AA before and after purification were measured after melting and pressing, and their infrared spectra corresponded to image 3 Curves 1-3 in. It can be seen from the figure that both curve 2 and curve 3 are at 1716cm -1 There is a charac...

Embodiment 2

[0064] Use polypropylene powder, DCP and AA as raw materials, add them into a stainless steel high-pressure reactor equipped with stirring and pressure sensors according to the mass ratio PP / AA / DCP=100 / 10.5 / 0.5, and use CO 2 After the air in the kettle was purged clean, an appropriate amount of CO was introduced. 2 ; Swell at 80°C and 9.2MPa for 1 hour; then, the temperature is raised to 140°C, and the corresponding pressure is 13.2MPa. At this time, DCP is thermally decomposed to initiate a free radical grafting reaction; after 4 hours of reaction, the CO in the kettle 2 Evacuate and take out the crude product of grafted PP-g-AA; finally, perform relevant characterization after extraction with absolute ethanol and degelation. Gained sample graft rate is 7.2%, and gel rate is 7.3%, the temperature (T when sample weight loss 5wt%) 5％ ) increased by 64°C, the complete decomposition temperature (T 100％ ) increased by 72°C, the maximum decomposition rate temperature T pm Increa...

Embodiment 3

[0066] Use polypropylene powder, DCP and AA as raw materials, add them into a stainless steel high-pressure reactor equipped with stirring and pressure sensors according to the mass ratio PP / AA / DCP=100 / 10.5 / 0.5, and use CO 2 After the air in the kettle was purged clean, an appropriate amount of CO was introduced. 2 ; Swell at 80°C and 10.5MPa for 1 hour; then, heat up to 130°C, corresponding to a pressure of 14MPa, at this time, DCP thermally decomposes to initiate a free radical grafting reaction; after 4 hours of reaction, the CO in the kettle 2 Evacuate and take out the crude product of graft PP-g-AA; finally, obtain purified PP-g-AA after extraction with absolute ethanol and degelation. The obtained sample had a graft rate of 7.9% and a gel rate of 8.8%.

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Abstract

The invention discloses a method for preparing polypropylene grafted with acrylic acid through supercritical carbon dioxide. The method comprises the following steps: (1) at a temperature of between 40 and 100 DEG C and the pressure of between 7 and 20 MPa, swelling polypropylene by the supercritical carbon dioxide and dissolving acrylic acid and an initiator; making acrylic acid and the initiator impregnate into a polypropylene matrix with the swelling and impregnation time of between 1 and 8 hours; (2) at the grafting reaction temperature of between 70 and 160 DEG C and the grafting reaction pressure of between 8 and 30 MPa, decomposing the initiator to initiate the grafting reaction; and (3) after reaction for 1 to 5 hours, carrying out decarbonation through pressure reduction so as to obtain the polypropylene grafted with the acrylic acid. The method with a simple operating process has no solvent reclaiming, thereby contributing to environmental protection. The prepared modified polypropylene has high grafting ratio, low crosslinking degree, even grafting and low graft degradation.

Description

technical field [0001] The invention relates to a method for preparing unsaturated organic acid grafted polypropylene, in particular to a method for preparing acrylic acid grafted polypropylene (PP-g-AA) by using supercritical carbon dioxide. Background technique [0002] By means of graft copolymerization, unsaturated organic acid is used to graft polypropylene to generate a high-performance graft polymer, which not only improves performance, but also satisfies its use as an adhesive and compatibilizer. [0003] At present, there are many methods for producing unsaturated organic acid grafted polypropylene, generally including solution method, melting method, solid phase method and suspension grafting method, but these methods have the disadvantages of low grafting rate, high cost, Defects such as large environmental pollution, a method for preparing unsaturated organic acid grafted polypropylene with supercritical carbon dioxide, because it can prepare a graft polymer with...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08F255/02C08F2/00D06M14/10
CPCY02P20/54
Inventor 童刚生刘涛赵玲袁渭康
Owner XIANGTAN UNIV
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