CN101113198A - Method for preparing high-molecular L-lactic acid by employing low-molecular-weight epoxide resin chain extender - Google Patents
Method for preparing high-molecular L-lactic acid by employing low-molecular-weight epoxide resin chain extender Download PDFInfo
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- CN101113198A CN101113198A CNA2007100237799A CN200710023779A CN101113198A CN 101113198 A CN101113198 A CN 101113198A CN A2007100237799 A CNA2007100237799 A CN A2007100237799A CN 200710023779 A CN200710023779 A CN 200710023779A CN 101113198 A CN101113198 A CN 101113198A
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- molecular weight
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- lactic acid
- epoxy resin
- chain extender
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- JVTAAEKCZFNVCJ-REOHCLBHSA-N L-lactic acid Chemical compound C[C@H](O)C(O)=O JVTAAEKCZFNVCJ-REOHCLBHSA-N 0.000 title claims abstract description 75
- 239000003822 epoxy resin Substances 0.000 title claims abstract description 37
- 229920000647 polyepoxide Polymers 0.000 title claims abstract description 37
- 238000000034 method Methods 0.000 title claims abstract description 33
- 239000004970 Chain extender Substances 0.000 title claims abstract description 29
- 125000000217 alkyl group Chemical group 0.000 claims abstract description 26
- LRWZZZWJMFNZIK-UHFFFAOYSA-N 2-chloro-3-methyloxirane Chemical compound CC1OC1Cl LRWZZZWJMFNZIK-UHFFFAOYSA-N 0.000 claims abstract description 12
- 238000006068 polycondensation reaction Methods 0.000 claims abstract description 8
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 45
- 239000003054 catalyst Substances 0.000 claims description 27
- 230000001588 bifunctional effect Effects 0.000 claims description 20
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims description 18
- 229920001432 poly(L-lactide) Polymers 0.000 claims description 12
- 239000013067 intermediate product Substances 0.000 claims description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- 239000007864 aqueous solution Substances 0.000 claims description 9
- 238000006243 chemical reaction Methods 0.000 claims description 9
- JRMUNVKIHCOMHV-UHFFFAOYSA-M tetrabutylammonium bromide Chemical compound [Br-].CCCC[N+](CCCC)(CCCC)CCCC JRMUNVKIHCOMHV-UHFFFAOYSA-M 0.000 claims description 8
- LZZYPRNAOMGNLH-UHFFFAOYSA-M Cetrimonium bromide Chemical compound [Br-].CCCCCCCCCCCCCCCC[N+](C)(C)C LZZYPRNAOMGNLH-UHFFFAOYSA-M 0.000 claims description 7
- 239000001361 adipic acid Substances 0.000 claims description 7
- ADCOVFLJGNWWNZ-UHFFFAOYSA-N antimony trioxide Chemical compound O=[Sb]O[Sb]=O ADCOVFLJGNWWNZ-UHFFFAOYSA-N 0.000 claims description 6
- CHQVQXZFZHACQQ-UHFFFAOYSA-M benzyl(triethyl)azanium;bromide Chemical compound [Br-].CC[N+](CC)(CC)CC1=CC=CC=C1 CHQVQXZFZHACQQ-UHFFFAOYSA-M 0.000 claims description 6
- 230000018044 dehydration Effects 0.000 claims description 6
- 238000006297 dehydration reaction Methods 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- 235000006408 oxalic acid Nutrition 0.000 claims description 6
- VXUYXOFXAQZZMF-UHFFFAOYSA-N titanium(IV) isopropoxide Chemical compound CC(C)O[Ti](OC(C)C)(OC(C)C)OC(C)C VXUYXOFXAQZZMF-UHFFFAOYSA-N 0.000 claims description 6
- 238000004821 distillation Methods 0.000 claims description 5
- 238000001035 drying Methods 0.000 claims description 5
- 238000001914 filtration Methods 0.000 claims description 5
- 239000002994 raw material Substances 0.000 claims description 5
- 150000003839 salts Chemical class 0.000 claims description 5
- 230000002194 synthesizing effect Effects 0.000 claims description 5
- 239000000243 solution Substances 0.000 claims description 4
- HWCKGOZZJDHMNC-UHFFFAOYSA-M tetraethylammonium bromide Chemical compound [Br-].CC[N+](CC)(CC)CC HWCKGOZZJDHMNC-UHFFFAOYSA-M 0.000 claims description 4
- KSBAEPSJVUENNK-UHFFFAOYSA-L tin(ii) 2-ethylhexanoate Chemical compound [Sn+2].CCCCC(CC)C([O-])=O.CCCCC(CC)C([O-])=O KSBAEPSJVUENNK-UHFFFAOYSA-L 0.000 claims description 4
- TXUICONDJPYNPY-UHFFFAOYSA-N (1,10,13-trimethyl-3-oxo-4,5,6,7,8,9,11,12,14,15,16,17-dodecahydrocyclopenta[a]phenanthren-17-yl) heptanoate Chemical compound C1CC2CC(=O)C=C(C)C2(C)C2C1C1CCC(OC(=O)CCCCCC)C1(C)CC2 TXUICONDJPYNPY-UHFFFAOYSA-N 0.000 claims description 3
- 229910021626 Tin(II) chloride Inorganic materials 0.000 claims description 3
- 229910021627 Tin(IV) chloride Inorganic materials 0.000 claims description 3
- 239000012043 crude product Substances 0.000 claims description 3
- CJGYQECZUAUFSN-UHFFFAOYSA-N oxygen(2-);tin(2+) Chemical compound [O-2].[Sn+2] CJGYQECZUAUFSN-UHFFFAOYSA-N 0.000 claims description 3
- 235000011150 stannous chloride Nutrition 0.000 claims description 3
- 239000001119 stannous chloride Substances 0.000 claims description 3
- QHGNHLZPVBIIPX-UHFFFAOYSA-N tin(II) oxide Inorganic materials [Sn]=O QHGNHLZPVBIIPX-UHFFFAOYSA-N 0.000 claims description 3
- HPGGPRDJHPYFRM-UHFFFAOYSA-J tin(iv) chloride Chemical compound Cl[Sn](Cl)(Cl)Cl HPGGPRDJHPYFRM-UHFFFAOYSA-J 0.000 claims description 3
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 2
- 229910052718 tin Inorganic materials 0.000 claims description 2
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 abstract description 5
- 231100000419 toxicity Toxicity 0.000 abstract description 4
- 230000001988 toxicity Effects 0.000 abstract description 4
- 239000000463 material Substances 0.000 abstract description 3
- 229940116871 l-lactate Drugs 0.000 abstract 6
- 239000004626 polylactic acid Substances 0.000 description 13
- JVTAAEKCZFNVCJ-UHFFFAOYSA-N lactic acid Chemical compound CC(O)C(O)=O JVTAAEKCZFNVCJ-UHFFFAOYSA-N 0.000 description 12
- 229920000747 poly(lactic acid) Polymers 0.000 description 11
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 239000004310 lactic acid Substances 0.000 description 6
- 235000014655 lactic acid Nutrition 0.000 description 6
- JJTUDXZGHPGLLC-UHFFFAOYSA-N lactide Chemical compound CC1OC(=O)C(C)OC1=O JJTUDXZGHPGLLC-UHFFFAOYSA-N 0.000 description 5
- 229920003023 plastic Polymers 0.000 description 5
- 239000004033 plastic Substances 0.000 description 5
- 238000002360 preparation method Methods 0.000 description 5
- BRLQWZUYTZBJKN-UHFFFAOYSA-N Epichlorohydrin Chemical compound ClCC1CO1 BRLQWZUYTZBJKN-UHFFFAOYSA-N 0.000 description 3
- -1 aromatic isocyanate Chemical class 0.000 description 3
- 238000003912 environmental pollution Methods 0.000 description 3
- RRAMGCGOFNQTLD-UHFFFAOYSA-N hexamethylene diisocyanate Chemical compound O=C=NCCCCCCN=C=O RRAMGCGOFNQTLD-UHFFFAOYSA-N 0.000 description 3
- 239000012948 isocyanate Substances 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 238000006116 polymerization reaction Methods 0.000 description 3
- 239000005057 Hexamethylene diisocyanate Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 239000012153 distilled water Substances 0.000 description 2
- 238000010528 free radical solution polymerization reaction Methods 0.000 description 2
- 150000002513 isocyanates Chemical class 0.000 description 2
- 238000010907 mechanical stirring Methods 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 238000007151 ring opening polymerisation reaction Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000001384 succinic acid Substances 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- LNRVTEQEGXVMEF-UHFFFAOYSA-N 2-hydroxy-2-methylpropanedioic acid Chemical group OC(=O)C(O)(C)C(O)=O LNRVTEQEGXVMEF-UHFFFAOYSA-N 0.000 description 1
- UPMLOUAZCHDJJD-UHFFFAOYSA-N 4,4'-Diphenylmethane Diisocyanate Chemical compound C1=CC(N=C=O)=CC=C1CC1=CC=C(N=C=O)C=C1 UPMLOUAZCHDJJD-UHFFFAOYSA-N 0.000 description 1
- 229920002472 Starch Polymers 0.000 description 1
- 229920003232 aliphatic polyester Polymers 0.000 description 1
- 244000309464 bull Species 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 125000004122 cyclic group Chemical class 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 231100000086 high toxicity Toxicity 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- IQPQWNKOIGAROB-UHFFFAOYSA-N isocyanate group Chemical group [N-]=C=O IQPQWNKOIGAROB-UHFFFAOYSA-N 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000013557 residual solvent Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 235000019698 starch Nutrition 0.000 description 1
- 239000008107 starch Substances 0.000 description 1
- DVKJHBMWWAPEIU-UHFFFAOYSA-N toluene 2,4-diisocyanate Chemical compound CC1=CC=C(N=C=O)C=C1N=C=O DVKJHBMWWAPEIU-UHFFFAOYSA-N 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
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- Polyesters Or Polycarbonates (AREA)
Abstract
A method to prepare high molecular weight poly L-lactate from low molecular weight epoxy resin chain extender, is characterized in that the carboxyl terminal L-lactate base prepolymer is synthesized through direct melt and polycondensation methods with the material L-lactate; the low molecular weight bifunctionality epoxy resin chain extender is synthesized with materials low molecular weight alkyl diacid and epoxychloropropane; finally high molecular weight poly L-lactate is prepared and synthesized by using the low molecular weight bifunctionality epoxy resin chain extender to chain extension the carboxyl terminal L-lactate base prepolymer. The invention makes use of the low molecular weight bifunctionality epoxy resin chain extender with small volatilization and toxicity to chain extension the carboxyl terminal L-lactate base prepolymer, which overcomes the disadvantages of Crisvon NX chain extender such as high volatilization and toxicity; furthermore, the technique to prepare the low molecular weight bifunctionality epoxy resin chain extender is simple.
Description
Technical Field
The invention relates to a method for synthesizing high molecular weight poly-L-lactic acid by chain extension of an end carboxyl group L-lactic acid prepolymer by using a low molecular weight bifunctional epoxy resin chain extender.
Background
Polylactic acid (PLA) is a high molecular material of aliphatic polyester group having excellent biocompatibility and being completely biodegradable. The raw material lactic acid can be prepared by fermenting starch and the like, and belongs to an environment renewable resource. Therefore, the plastic solves two problems of plastic development: firstly, the environmental pollution caused by a large amount of waste plastics is increasingly serious; and the petroleum resources depended by the general plastic are limited and are in more and more shortage. According with the sustainable development strategy advocated in the world today.
The synthesis of polylactic acid generally has two routes, i.e., an open-loop polymerization method and a direct polycondensation method. The ring-opening polymerization method is firstly used for preparing the cyclic dimer-lactide of the lactic acid, and the lactide is subjected to ring-opening polymerization to obtain the polylactic acid. The method requires high-purity lactide, the purification process of the lactide is complex, the consumption is high, the yield is low, and in addition, the lactide is easy to absorb water and is not beneficial to long-time storage. Thus, the obtained polylactic acid has high price and is difficult to compete with general plastics.
The direct polycondensation method mainly includes a solution polymerization method and a melt polymerization method. Chinese patent CN1298892A discloses a solution polymerization method for direct polycondensation of lactic acid into polylactic acid. Although the method can synthesize polylactic acid with higher molecular weight, the post-treatment is relatively complex, the cost is still higher, and the residual solvent in the final product is difficult to remove.
In melt polymerization, there is a complex balance between free lactic acid, water, polymer, and by-product lactide. Therefore, the relative molecular weight of the polylactic acid synthesized by the method is often less than 4000, the strength is low, the practical value is not high, and the molecular weight of the polylactic acid has better physical and mechanical properties only when the molecular weight is more than 25000.
The two ends of the molecular chain of the melt-condensed low molecular weight polylactic acid are provided with reactive tube energy groups, and the molecular weight of the low molecular weight polylactic acid can be improved by adopting a chain extension method, and more patents and papers have been reported on the research on the aspect. Woo et al (Polym Bull, 1995, VOL.35, NO.4, P415) used Hexamethylene Diisocyanate (HDI) as a chain extender to adjust the mass average molecular weight (M) of polylactic acidw) Increased to 76000. Harkonen et al (J Macromol Sci Pure apple Chem, 1995, VOL.32, NO.4, P)857) Firstly, preparing a polylactic acid telechelic prepolymer with terminal hydroxyl, and then carrying out HDI chain extension to obtain a product with the number average relative molecular mass of 57000. National sources of Mingzhijiang et al (petrochemical, 2001, VOL.30, NO.2, P103) adopt aromatic isocyanate (toluene diisocyanate, diphenylmethane diisocyanate and trifunctional isocyanate) as a chain extender to chain extend lactic acid, and the relative molecular mass of the obtained polymer is up to hundreds of thousands. Therefore, isocyanate is generally used as a chain extender, and has high toxicity, great harm to the health of operators in the chain extension process and environmental pollution. CN1563139A reports that 1, 2-epoxy octanoyl chloride is adopted to chain extend lactic acid prepolymer to prepare high molecular weight polylactic acid, but the requirement on the synthesis condition of the chain extender is high.
Disclosure of Invention
The invention aims to avoid the defects of the prior art and provides a method for preparing high molecular weight poly-L-lactic acid by using a low molecular weight epoxy resin chain extender, which is a method for preparing high molecular weight poly-L-lactic acid by using a low molecular weight bifunctional epoxy resin chain extender to chain an end carboxyl group L-lactic acid prepolymer, so that the preparation process is safe, non-toxic and harmless, no environmental pollution is caused, and the preparation process of the chain extender is simple.
The invention adopts the following technical scheme for solving the technical problems:
the method of the invention is characterized by comprising the following steps:
a. synthesizing a carboxyl-terminated L-lactic acid prepolymer by taking L-lactic acid as a raw material through a direct melt polycondensation method;
b. synthesizing a low molecular weight bifunctional epoxy resin chain extender by using low molecular weight alkyl diacid and epoxy chloropropane as raw materials;
c. and (c) utilizing the low molecular weight bifunctional epoxy resin chain extender in the step (b) to carry out chain extension on the carboxyl-terminated L-lactic acid prepolymer in the step (a) so as to synthesize high molecular weight poly-L-lactic acid.
The method of the invention is also characterized in that:
and step a, dehydrating the L-lactic acid at 100-150 ℃ under the condition of 1000-2000 Pa until the water content is 1-2%, adding low molecular weight alkyl diacid and a catalyst, and reacting for 5-30 hours at 140-200 ℃ under the condition of 0.1-2000 Pa to obtain a carboxyl-terminated L-lactic acid prepolymer.
Wherein the low molecular weight alkyl diacid comprises oxalic acid, 1, 4-succinic acid, 1, 6-adipic acid and 1, 10-sebacic acid, and the dosage of the low molecular weight alkyl diacid accounts for 0.5-4% of the mass of the L-lactic acid after dehydration according to the mass percentage; the catalyst comprises stannous octoate, stannous chloride, stannic chloride, stannous oxide, tin, antimony trioxide, tetra-n-butyl titanate and tetra-isopropyl titanate, and the dosage of the catalyst is 0.01-1.0% of the mass of the L-lactic acid after dehydration according to mass percent.
The method of the invention is also characterized in that:
the preparation of the low molecular weight bifunctional epoxy resin chain extender in the step b is as follows:
respectively adding epoxy chloropropane and a catalyst into low-molecular-weight alkyl diacid, and reacting for 1-3 hours at the temperature of 90-110 ℃; after the reaction is finished, carrying out reduced pressure distillation on the mixture at the temperature of 80-90 ℃ and under the condition of 1000-5000 Pa to recover unreacted epoxy chloropropane, thus obtaining an intermediate product; preparing NaOH into NaOH aqueous solution with the mass concentration of 30%, slowly dripping the NaOH aqueous solution into the intermediate product, and reacting for 0.5-3 hours at the temperature of 30-40 ℃; filtering the obtained crude product of the low molecular weight bifunctional epoxy resin, removing generated salt, and adding NaH with the mass concentration of 20%2PO4Neutralizing the water solution to pH 6.5-7.0, and removing water layer; drying the epoxy resin to constant weight at 70-90 ℃ under the condition of 1000-5000 Pa to obtain the required low-molecular-weight bifunctional epoxy resin; wherein,
the molar ratio of the low molecular weight alkyl diacid to the epoxy chloropropane is 1: 6-20;
the catalyst is 0.1-2% of low molecular weight alkyl diacid by mass percent;
the molar ratio of the low molecular weight alkyl diacid to NaOH is 1: 2.
Wherein the low molecular weight alkyl diacid comprises oxalic acid, 1, 4-succinic acid, 1, 6-adipic acid and 1, 10-sebacic acid; the catalyst comprises tetra-n-butylammonium bromide, hexadecyltrimethylammonium bromide and benzyltriethylammonium bromide.
The method of the invention is also characterized in that:
and c, adding a catalyst accounting for 0.1-2% by mass of the carboxyl-terminated L-lactic acid prepolymer into the carboxyl-terminated L-lactic acid prepolymer and the low-molecular-weight bifunctional epoxy resin in equal moles, and reacting for 10-120 minutes at the temperature of 150-180 ℃ to obtain the high-molecular-weight L-lactic acid.
Wherein the catalyst comprises tetra-n-butylammonium bromide, tetraethylammonium bromide, hexadecyltrimethylammonium bromide and benzyltriethylammonium bromide.
Compared with the prior art, the invention has the beneficial effects that:
the invention utilizes the low molecular weight bifunctionality epoxy resin chain extender which has no volatilization and small toxicity to carry out chain extension on the terminal carboxyl L-lactic acid prepolymer to prepare the high molecular weight poly L-lactic acid, overcomes the defects of high volatility and large toxicity of isocyanate chain extenders, and has simple preparation process of the low molecular weight epoxy resin chain extender.
Detailed Description
1. Preparing a carboxyl-terminated L-lactic acid prepolymer by melt polycondensation:
dehydrating the L-lactic acid for 2-4 hours at the temperature of 100-150 ℃ and the pressure of 1000-2000 Pa, respectively adding low molecular weight alkyl diacid with the mass percentage of 0.5-4% of the L-lactic acid after dehydration and 0.01-1.0% of catalyst, and reacting for 5-30 hours at the temperature of 140-200 ℃ and the pressure of 0.1-2000 Pa to obtain a carboxyl-terminated L-lactic acid prepolymer.
In specific implementation, the melt polycondensation catalyst comprises stannous octoate, stannous chloride, stannic chloride, stannous oxide, stannic, antimony trioxide, tetra-n-butyl titanate, and tetra-isopropyl titanate. The low molecular weight alkyl diacid includes oxalic acid, 1, 4-succinic acid, 1, 6-adipic acid and 1, 10-sebacic acid.
2. Preparation of low molecular weight difunctional epoxy resin:
adding epoxy chloropropane with the molar ratio 6-20 times of that of the low-molecular-weight alkyl diacid into the low-molecular-weight alkyl diacid, adding a catalyst with the mass percent of 0.1-2 wt% of the low-molecular-weight alkyl diacid, and reacting for 1-3 hours at the temperature of 90-110 ℃. And after the reaction is finished, carrying out reduced pressure distillation on the mixture at the temperature of 80-90 ℃ and under the condition of 1000-5000 Pa to recover unreacted epoxy chloropropane, thus obtaining an intermediate product. NaOH with the molar ratio being twice of that of the low molecular weight alkyl diacid is taken to prepare NaOH aqueous solution with the mass concentration of 30%, the NaOH aqueous solution is slowly dripped into the intermediate product, and the reaction is carried out for 0.5 to 3 hours at the temperature of 30 to 40 ℃. Filtering the obtained crude product of the low molecular weight bifunctional epoxy resin, removing generated salt, and adding NaH with the mass concentration of 20%2PO4The aqueous solution was neutralized to pH 6.5-7.0, transferred to a separatory funnel, and the aqueous layer was removed. Drying the epoxy resin to constant weight at 70-90 ℃ under the condition of 1000-5000 Pa to obtain the required low-molecular-weight bifunctional epoxy resin.
In specific implementation, the low molecular weight alkyl diacid includes oxalic acid, 1, 4-succinic acid, 1, 6-adipic acid and 1, 10-sebacic acid. The catalyst used comprises tetra-n-butylammonium bromide, hexadecyltrimethylammonium bromide and benzyltriethylammonium bromide.
3. Chain extension:
weighing a carboxyl-terminated L-lactic acid prepolymer and a low-molecular-weight bifunctional epoxy resin in a molar ratio of 1: 1, adding a catalyst accounting for 0.1-2% of the carboxyl-terminated L-lactic acid prepolymer in percentage by mass, and reacting for 10-120 min at the temperature of 150-180 ℃ to obtain the low-molecular-weight epoxy resin chain extender chain-extended high-molecular-weight poly-L-lactic acid.
In specific embodiments, the catalyst used comprises tetra-n-butylammonium bromide, tetraethylammonium bromide, cetyltrimethylammonium bromide, benzyltriethylammonium bromide.
Example 1:
400g of 85 wt% L-lactic acid was taken in a 1000mL single neck round bottom flask. The flask was placed on a rotary evaporator at 100rpm in a 100 ℃ oil bath and dehydrated for 2 hours at 1000 Pa. Filling nitrogen to release pressure, adding 1, 4-succinic acid with the mass of 0.5 percent of that of the L-lactic acid after dehydration and stannous octoate catalyst with the mass of 0.5 percent of that of the L-lactic acid after dehydration, raising the temperature of an oil bath to 180 ℃, keeping the rotating speed of a rotary evaporator at 100rpm, gradually reducing the pressure to 100Pa, reacting for 10 hours, and pouring into a stainless steel disc after the reaction is finished. The carboxyl-terminated L-lactic acid prepolymer with the number average molecular weight of 3600 is obtained.
19.3g of 1, 4-succinic acid is put into a 250mL three-neck flask, 105.8g of epoxy chloropropane and 0.25g of tetrabutylammonium bromide catalyst are added, and the mixture reacts for 1.5 hours at the temperature of 105 ℃. Pouring the mixture into a 250mL single-neck flask after the reaction is finished, placing the flask on a rotary evaporator, and carrying out reduced pressure distillation at 80 ℃ under the condition of 2500Pa to recover unreacted epichlorohydrin so as to obtain an intermediate product. 13.1g of solid NaOH was dissolved in 30.5g of distilled water, and the NaOH solution was slowly dropped into the intermediate product to react at 30 ℃ for 1 hour. Filtering to remove the salt. Then adding NaH with the mass concentration of 20 percent2PO4The aqueous solution was adjusted to pH 7.0, and then transferred to a separatory funnel and allowed to stand to separate the aqueous layer. Drying at 80 deg.C and 2500Pa to constant weight to obtain bifunctional epoxy resin with molecular weight of 230.
200g of carboxyl-terminated L-lactic acid prepolymer, 12.8g of bifunctional epoxy resin chain extender and 0.6g of tetra-n-butylammonium bromide catalyst were weighed and placed in a 500mL three-neck flask with mechanical stirring and nitrogen protection, and heated in an oil bath to 180(, reaction 30 minutes. the poly L-lactic acid prepared therefrom was tested for mass average molecular weight M by GPC)wIs 7.3 ten thousand.
Example 2:
the carboxyl-terminated L-lactic acid prepolymer was prepared as in example 1.
20g of 1, 6-adipic acid is put into a 250mL three-neck flask, 140g of epichlorohydrin and 0.4g of hexadecyl trimethyl ammonium bromide catalyst are added, and the reaction is carried out for 1.5 hours at the temperature of 105 ℃. Pouring the mixture into a 250mL single-neck flask after the reaction is finished, placing the flask on a rotary evaporator, and carrying out reduced pressure distillation at 80 ℃ under the condition of 2500Pa to recover unreacted epichlorohydrin so as to obtain an intermediate product. 11.0g of solid NaOH was dissolved in 25.7g of distilled water, and the NaOH solution was slowly dropped into the intermediate product to react at 30 ℃ for 1 hour. Filtering to remove the salt. Then adding NaH with the mass concentration of 20 percent2PO4The aqueous solution was adjusted to pH 7.0, and then transferred to a separatory funnel and allowed to stand to separate the aqueous layer. Drying at 80 deg.C and 2500Pa to constant weight to obtain bifunctional epoxy resin with molecular weight of 258.
200g of carboxyl-terminated L-lactic acid prepolymer, 14.3g of bifunctional epoxy resin chain extender and 0.8g of tetraethylammonium bromide catalyst are weighed and placed in a 500mL three-neck flask with mechanical stirring and nitrogen protection device, heated to 180 ℃ in an oil bath and reacted for 30 min. Obtaining the mass average molecular weight M measured by GPCw8.6 million of poly-L-lactic acid.
Claims (7)
1. A method for preparing high molecular weight poly-L-lactic acid by using a low molecular weight epoxy resin chain extender is characterized by comprising the following steps:
a. synthesizing a carboxyl-terminated L-lactic acid prepolymer by taking L-lactic acid as a raw material through a direct melt polycondensation method;
b. synthesizing a low molecular weight bifunctional epoxy resin chain extender by using low molecular weight alkyl diacid and epoxy chloropropane as raw materials;
c. and (c) utilizing the low molecular weight bifunctional epoxy resin chain extender in the step (b) to carry out chain extension on the carboxyl-terminated L-lactic acid prepolymer in the step (a) so as to synthesize high molecular weight poly-L-lactic acid.
2. The method of claim 1, wherein the step a is to dehydrate L-lactic acid at 100-150 ℃ and 1000-2000 Pa to water content of 1-2%, add low molecular weight alkyl diacid and catalyst, and react at 140-200 ℃ and 0.1-2000 Pa for 5-30 hours to obtain carboxyl-terminated L-lactic acid prepolymer.
3. The method as claimed in claim 2, wherein the low molecular weight alkyl diacid comprises oxalic acid, 1, 4-succinic acid, 1, 6-adipic acid and 1, 10-sebacic acid, and the amount of the low molecular weight alkyl diacid is 0.5-4% of the mass of the dehydrated L-lactic acid; the catalyst comprises stannous octoate, stannous chloride, stannic chloride, stannous oxide, tin, antimony trioxide, tetra-n-butyl titanate and tetra-isopropyl titanate, and the dosage of the catalyst is 0.01-1.0% of the mass of the L-lactic acid after dehydration according to mass percent.
4. The method as set forth in claim 1, wherein said low molecular weight difunctional epoxy resin chain extender in step b is prepared by:
respectively adding epoxy chloropropane and a catalyst into low-molecular-weight alkyl diacid, and reacting for 1-3 hours at the temperature of 90-110 ℃; after the reaction is finished, carrying out reduced pressure distillation on the mixture at the temperature of 80-90 ℃ and under the condition of 1000-5000 Pa to recover unreacted epoxy chloropropane, thus obtaining an intermediate product; preparing NaOH into NaOH aqueous solution with the mass concentration of 30%, slowly dripping the NaOH aqueous solution into the intermediate product, and reacting for 0.5-3 hours at the temperature of 30-40 ℃; filtering the obtained crude product of the low molecular weight bifunctional epoxy resin, removing generated salt, and adding NaH with the mass concentration of 20%2PO4Neutralizing the water solution to pH 6.5-7.0, and removing water layer; drying the epoxy resin to constant weight at 70-90 ℃ under the condition of 1000-5000 Pa to obtain the required low-molecular-weight bifunctional epoxy resin; wherein,
the molar ratio of the low molecular weight alkyl diacid to the epoxy chloropropane is 1: 6-20;
the catalyst is 0.1-2% of low molecular weight alkyl diacid by mass percent;
the molar ratio of the low molecular weight alkyl diacid to NaOH is 1: 2.
5. The process as set forth in claim 4, characterized in that the low molecular weight alkyl diacids comprise oxalic acid, 1, 4-succinic acid, 1, 6-adipic acid, 1, 10-sebacic acid; the catalyst comprises tetra-n-butylammonium bromide, hexadecyltrimethylammonium bromide and benzyltriethylammonium bromide.
6. The method as claimed in claim 1, wherein in the step c, the carboxyl-terminated L-lactic acid prepolymer and the low molecular weight bifunctional epoxy resin are added with a catalyst in an amount of 0.1-2% by weight of the carboxyl-terminated L-lactic acid prepolymer, and reacted at 150-180 ℃ for 10-120 minutes to obtain the high molecular weight poly-L-lactic acid.
7. The method as set forth in claim 6, wherein the catalyst comprises tetra-n-butylammonium bromide, tetraethylammonium bromide, hexadecyltrimethylammonium bromide, benzyltriethylammonium bromide.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105330640A (en) * | 2015-10-26 | 2016-02-17 | 中国科学院长春应用化学研究所 | Preparation method for high chemical purity lactide |
| CN107474233A (en) * | 2017-08-20 | 2017-12-15 | 芜湖通全科技有限公司 | A kind of preparation method of PLA base epoxy |
| CN112851923A (en) * | 2019-11-12 | 2021-05-28 | 上海竞微扶生医学科技有限公司 | Modified polycaprolactone implant material and preparation method thereof, fiber and preparation method thereof, and patch |
-
2007
- 2007-07-13 CN CNB2007100237799A patent/CN100528928C/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105330640A (en) * | 2015-10-26 | 2016-02-17 | 中国科学院长春应用化学研究所 | Preparation method for high chemical purity lactide |
| CN107474233A (en) * | 2017-08-20 | 2017-12-15 | 芜湖通全科技有限公司 | A kind of preparation method of PLA base epoxy |
| CN112851923A (en) * | 2019-11-12 | 2021-05-28 | 上海竞微扶生医学科技有限公司 | Modified polycaprolactone implant material and preparation method thereof, fiber and preparation method thereof, and patch |
| CN112851923B (en) * | 2019-11-12 | 2023-03-24 | 上海竞微扶生医学科技有限公司 | Modified polycaprolactone implant material and preparation method thereof, fiber and preparation method thereof, and patch |
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| CN100528928C (en) | 2009-08-19 |
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