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Preparation method of lactic acid copolymer with high relative molecular mass

A relative molecular weight and lactic acid copolymerization technology, which is applied in the field of preparation of high relative molecular weight lactic acid copolymers, can solve the problems of increased cost, unsatisfactory mixing effect, poor compatibility, etc., and achieve good results

Inactive Publication Date: 2020-03-24
广东炬盛新材料科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] In the process of preparing copolymers in tank reactors, as the polymerization reaction proceeds, the viscosity of the reaction system is getting higher and higher, which seriously hinders the continuation of the reaction. Usually, the synthesized PLLA is very brittle and cannot be melt-processed. Sometimes it is necessary to add a toughening agent, or blend with other materials, and the viscosity will increase in the later stage of the reaction, and the mixing effect of the two components is not ideal. Synthesizing PLLA with high relative molecular weight will increase the step of blending, and the cost will increase. The capacity is also very poor, and the product performance becomes poor

Method used

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  • Preparation method of lactic acid copolymer with high relative molecular mass
  • Preparation method of lactic acid copolymer with high relative molecular mass
  • Preparation method of lactic acid copolymer with high relative molecular mass

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Experimental program
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Embodiment 1

[0033] Such as figure 1 As shown, the invention discloses a method for preparing a high relative molecular weight lactic acid copolymer, including preparing a PLA prepolymer, preparing a PCL prepolymer and preparing a PLA copolymer by twin-screw reactive extrusion.

[0034] The preparation method of PLA prepolymer is the direct melt polycondensation reaction of lactic acid, and the specific steps are: by adding lactic acid in the reaction system, stirring and heating up in a vacuum environment, and adding stannous chloride for vacuum dehydration reaction.

[0035] The specific steps of the PCL prepolymer preparation method are:

[0036] S1: Vacuum dehydrate accurately measured PCL at 120°C for 1-2 hours;

[0037] S2: Cool to 50°C, release the vacuum, add to 1,6-hexamethylene diisocyanate, and protect with nitrogen;

[0038] S3: The reaction is exothermic. After the system naturally heats up for 30-40 minutes, it is slowly heated to 85°C, and the reaction is kept for 2-3 hour...

Embodiment 2

[0042] The reaction process of PLLA and PCL prepolymer was tracked by heating infrared:

[0043] First, a certain amount of PLLA and PCL were dissolved in anhydrous chloroform in a certain proportion, then the two solutions were mixed and stirred evenly, and then coated on a glass slide, and then dried in a vacuum dryer for 4 to 5 hours, and finally blended The material film is tested with the American NicoletNEXUS-670 FTIR spectrometer by the transmission method under different heating conditions.

[0044] In order to investigate the reactivity of PLLA with PCL prepolymer (OCN-PCL-NCO), we tracked the reaction process of the two with warming infrared. See you separately figure 2 , 3, 4, 5.

[0045] From figure 2 (a) 20°C, (b) 60°C, (c) 90°C, (d) 105°C, (e) 120°C, (f) 135°C, (g) 145°C, (h) 160°C , it can be seen that the blend of PLLA and PCL prepolymer at 2270cm -1 There is a characteristic absorption peak of -NCO end group. During the heating process, due to the fast...

Embodiment 3

[0050] The influence of the copolymer ratio on the relative molecular mass of the copolymerized product:

[0051] The relative molecular weight of polymers directly affects many properties of polymers. We first prepared PLA copolymers with different PCL ratios to investigate its influence on the relative molecular weight of the product. Using a copolymerization temperature of 180°C and a copolymerization time of 9 minutes, the relative molecular weights of PLLA and its copolymers were measured by viscometry, and the results are listed in Table 1.

[0052] From the data in Table 1, it can be seen that after the chain extension reaction between PLLA and PCL prepolymer, the relative molecular weight has been greatly improved. It reacts with the terminal -OH group of PLLA, and can also react with -COOH at high temperature, so that the molecular chain of PLLA increases and the relative molecular weight increases. And it can be seen that with the increase of the PCL prepolymer con...

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Abstract

The invention relates to the field of polymer materials, and discloses a preparation method of a lactic acid copolymer with high relative molecular mass. The preparation method comprises the steps ofpreparing a PLA prepolymer, preparing a PCL prepolymer and preparing a PLA copolymer through double-screw reactive extrusion. Polylactic acid with a certain relative molecular mass is synthesized by amelt polycondensation method and then is copolymerized with a polyurethane prepolymer of polycaprolactone polyol, the lactic acid copolymer is extruded by a double-screw reactor to prepare the lacticacid copolymer with high relative molecular mass, and the lactic acid copolymer prepared through the double-screw reactive extrusion is thermoplastic and has a better mixing effect than a kettle-typereaction. Through reasonable configuration, the product obtained through double-screw reactive extrusion has good mechanical properties, the toughness of the reaction extrusion product is improved due to increase of the PCL content, and the tensile strength and the tensile modulus are reduced.

Description

technical field [0001] The invention relates to the field of polymer materials, in particular to a method for preparing a high molecular weight lactic acid copolymer. Background technique [0002] In the process of preparing copolymers in tank reactors, as the polymerization reaction proceeds, the viscosity of the reaction system is getting higher and higher, which seriously hinders the continuation of the reaction. Usually, the synthesized PLLA is very brittle and cannot be melt-processed. Sometimes it is necessary to add a toughening agent, or blend with other materials, and the viscosity will increase in the later stage of the reaction, and the mixing effect of the two components is not ideal. Synthesizing PLLA with high relative molecular weight will increase the step of blending, and the cost will increase. Capacitance is also very poor, and product performance becomes poor. [0003] The inventors have established a brand-new process route for the preparation of high m...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G18/10C08G18/42C08G63/08C08G63/78
CPCC08G18/10C08G18/4277C08G63/08C08G63/78C08G18/428
Inventor 邹洁李峥嵘
Owner 广东炬盛新材料科技有限公司
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