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Preparation method of aliphatic polycarbonate with high molecular weight

A polycarbonate, high molecular weight technology, applied in the field of aliphatic polycarbonate preparation, can solve the problems of high toxicity of phosgene, decarbonation, difficulty, etc., avoid catalyst separation process, improve heat resistance, and low cost of raw materials Effect

Active Publication Date: 2012-01-11
INST OF CHEM CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The production raw materials in the phosgene method are phosgene and diols. Due to the high toxicity of phosgene and the large amount of waste water generated during the production process, the production conditions are harsh and the pollution is relatively large, so it has been basically eliminated.
In the ring-opening polymerization method of cyclic carbonates, polycarbonates with higher molecular weight can be synthesized by ring-opening polymerization of six-membered and more than six-membered cyclic carbonates, but most of the cyclic carbonates are made by the phosgene method, and there are also Pollution
In addition, decarbonation occurs during the ring-opening process of five-membered ring carbonates. Most studies have focused on the ring-opening polymerization of six-membered ring carbonates, which greatly limits the types of aliphatic polycarbonates prepared by this method.
Carbon dioxide / epoxide regulated copolymerization method also can only synthesize the polycarbonate of specific structure, and needs to use a large amount of catalyzers in the preparation process, will remove a large amount of catalyzers from the product of high viscosity simultaneously; In addition, this The aliphatic polycarbonates prepared by this method are all in an amorphous state, which leads to poor heat resistance of the polymer
But the molecular weight of the prepared aliphatic polycarbonate of prior art is all very little (no more than 2000), as US 2789946, US 3000849, CN 1616407A etc., can't be directly used as plastics at all, but as preparation polycarbonate type polyurethane The use of raw materials
US 3544524 utilizes aryl carbonate as a raw material to react with small molecule diol to synthesize high molecular weight aliphatic polycarbonate, but the utilization rate of carbonate is too low (aryl is finally discharged from the reaction vessel in the form of phenol), thus limits the application of this reaction

Method used

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  • Preparation method of aliphatic polycarbonate with high molecular weight
  • Preparation method of aliphatic polycarbonate with high molecular weight
  • Preparation method of aliphatic polycarbonate with high molecular weight

Examples

Experimental program
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Effect test

Embodiment 1

[0029] Embodiment 1, preparation aliphatic polycarbonate

[0030] In a 250ml glass flask, add 30g dimethyl carbonate, 60g 1,4-butanediol and 0.25ml tetrabutyl titanate (the molar ratio of dimethyl carbonate to 1,4-butanediol 1:2), start the reaction with stirring at 120°C, gradually raise the temperature to 225°C, each temperature stage must react completely before heating up, that is, no methanol will be distilled out, until all the methanol produced and unreacted dimethyl carbonate All esters were distilled off. Add 0.2ml of tetrabutyl titanate, and polycondense at 240°C for 5 hours under the pressure of less than 200Pa to finally obtain 25g of polycarbonate A with an intrinsic viscosity of 0.86dl / g and a number average molecular weight of 24300. The polycarbonate 1 H-NMR spectrum as figure 1 As shown, the FT-IR spectrum is as figure 2 shown. Depend on figure 1 It can be seen that the structure of the polymer is correct; figure 2 Medium, 2966cm -1 、1743cm -1 、7245...

Embodiment 2

[0031] Embodiment 2, prepare aliphatic polycarbonate

[0032]In a 250ml glass flask, add 90g dimethyl carbonate, 30g 1,4-butanediol and 0.005g potassium carbonate under nitrogen atmosphere (the molar ratio of dimethyl carbonate to 1,4-butanediol is 3:1 ), start the reaction with stirring at 120°C, and then gradually increase the temperature to 225°C (each temperature stage must react completely before heating up, that is, no methanol will be distilled), until all the methanol produced and unreacted dimethyl carbonate are completely Evaporate; add 0.15g of lithium carbonate, polycondensate at 240°C for 5 hours under a pressure lower than 200Pa, and finally obtain 30g of polycarbonate B with an intrinsic viscosity of 1.51dl / g and a number average molecular weight of 55,400.

Embodiment 3

[0033] Embodiment 3, preparation aliphatic polycarbonate

[0034] In a 250ml glass flask, add 55g dimethyl carbonate, 52g 1,5-pentanediol and 0.002g of manganese acetate (the mol ratio of dimethyl carbonate to 1,5-pentanediol is 1: 1.22), start the reaction with stirring at 120°C, and then gradually increase the temperature to 225°C (each temperature stage must react completely before heating up, that is, no methanol will be distilled out), until all the methanol produced and unreacted dimethyl carbonate All was evaporated; 0.2g of lithium carbonate was added, polycondensed for 6 hours at 250°C and a pressure lower than 200Pa, and finally 58g of polycarbonate C was obtained, with an intrinsic viscosity of 1.08dl / g and a number average molecular weight of 35,000.

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Abstract

The invention discloses aliphatic polycarbonate with high molecular weight and a preparation method thereof. The method comprises the following steps: in inert atmosphere, gradually heating divalent alcohol and carbonic ester under the action of a catalyst to complete an ester exchange reaction, and completely removing methyl alcohol generated in the process of the reaction to obtain a prepolymerof the aliphatic polycarbonate; and adding a polycondensation catalyst into the reaction system, and carrying out a polycondensation reaction in vacuum to obtain a product. The method has low cost ofraw materials and higher utilization ratio, reduces the cost of the product greatly, overcomes the defect of high cost of biodegradable materials, uses less dosage of catalyst in the reaction process, and avoids the complicated catalyst separation process. The aliphatic polycarbonate obtained by the method is white crystalline solid, has the number average molecular weight of between 6,000 and 2*10<5>, and can be directly used as plastics, does not contain an ether bond in the main chain of the polycarbonate, is a crystalline polymer, and greatly improves the heat-resistant quality of the polymer.

Description

technical field [0001] The invention relates to a method for preparing high-molecular-weight aliphatic polycarbonate, in particular to a method for preparing aliphatic polycarbonate through the two-step reaction of transesterification and polycondensation of carbonate and aliphatic dihydric alcohol. Background technique [0002] Aliphatic polycarbonate is a new type of fully biodegradable polymer material, its molecular structure is as follows: [0003] [0004] R in the above formula represents an aliphatic or alicyclic hydrocarbon group with 2-50 carbon atoms, n=10-2000. [0005] Aliphatic polycarbonate is a new class of completely biodegradable materials. It has good biocompatibility and physical and mechanical properties; there are many varieties, and the polymer can have a wide range of physical, chemical and biological properties by changing the chemical structure of the main chain to meet different needs; it can be introduced in a variety of ways Various types of...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08G64/02C08G64/00C08G64/30
Inventor 朱文祥李春成殷明肖耀南张栋管国虎
Owner INST OF CHEM CHINESE ACAD OF SCI
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