CN101585911B - Method for preparing branching or micro-cross-linking polylactic acid by one kettle - Google Patents

Method for preparing branching or micro-cross-linking polylactic acid by one kettle Download PDF

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CN101585911B
CN101585911B CN2009100881925A CN200910088192A CN101585911B CN 101585911 B CN101585911 B CN 101585911B CN 2009100881925 A CN2009100881925 A CN 2009100881925A CN 200910088192 A CN200910088192 A CN 200910088192A CN 101585911 B CN101585911 B CN 101585911B
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lactic acid
average functionality
acid
temperature
polylactic acid
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CN101585911A (en
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付志峰
曹鼎
石艳
李从举
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Beijing University of Chemical Technology
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Beijing University of Chemical Technology
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Abstract

The invention discloses a method for preparing branching or micro-cross-linking polylactic acid by one kettle. The average functionality degree of the system can be controlled by adding dihydroxy ethylformic acid and so on other components, a high molecular weight polylactic acid can be prepared by melting polycondensation; the average functionality degree can be controlled by theoretical calculation, the polycondensation reaction degree can be controlled during polymerization, thereby controlling the polylactic acid molecular weight; the product toughness can be improved by adding soft segment such as tetrahydrofuran polyether. The invention can obtain high molecular weight polylactic acid with strong toughness by reasonable designed prescription. Moreover, the preparing method of the invention is simple, the costs are low, the polymerization process is easy to control, under the precondition without influencing the processing performance, the high molecular weight polylactic acid product can be obtained, the method is suitable for the popularization of the polylactic acid product.

Description

One still prepares the method for branching or micro-cross-linking polylactic acid
Technical field
The invention belongs to polymeric material field, be specifically related to the method that a still prepares branching or micro-cross-linking polylactic acid.
Background technology
Along with the development of society, the crude oil price that chemical industry relied on is high, and along with a large amount of uses, world oil can reduce year by year for the amount of exploitation.Simultaneously petroleum products use and the extinction process in be easy to generate various societies and environmental problem such as pollution.The universal material of development environmental protection, especially starting material have recyclability, become the problem that chemical boundary and material circle are needed solution badly.
Poly(lactic acid) (PLA) is to study Biodegradable material widely at present.Its material acid can be obtained by biological fermentation, and last product again can be by the biological degradation back to nature, and poly(lactic acid) is a kind of organic materials that can not bring the environmental type of pollution all along.The applicability poly(lactic acid) adopts rac-Lactide ring-opening polymerization and two kinds of methods of direct polycondensation method to make at present.Rac-Lactide ring-opening polymerization method preparation process complexity, technology are tediously long, especially in the recrystallization process of rac-Lactide, will consume a lot of solvents and precipitation agent, and the productive rate of rac-Lactide is very low, makes the product cost height, the poly(lactic acid) that obtains costs an arm and a leg, and has seriously limited the popularization of poly-lactic acid products.Therefore, wish to obtain breaking through, reduce cost guaranteeing that molecular weight satisfies on the basis of application requiring, simplify processing condition from the poly(lactic acid) direct polycondensation method.The poly(lactic acid) direct polycondensation method can be divided into melt-polycondensation, solution azeotropy method, chain extension direct polycondensation method and process for solid state polycondensation substantially.Wherein, the product of melt-polycondensation preparation is purer, but the products obtained therefrom molecular weight is not too high, needs improvement badly; The solution azeotropy method has been introduced a large amount of solvents, has increased cost, and solvent itself has certain toxicity, has limited the application of product.
Summary of the invention
It is simple to the objective of the invention is to propose a kind of technology, and preparation with low cost has the method for the poly-lactic acid in high molecular weight of branching or little crosslinking structure.
One still prepares the method for branching or micro-cross-linking polylactic acid, it is characterized in that, may further comprise the steps: with lactic acid and interpolation component, under the effect of catalyzer, at 120-170 ℃ of following pre-polymerization 3-6 hour; In temperature 160-200 ℃, polycondensation pressure was less than polycondensation 3-12 under the 1000Pa condition hour then;
Control average functionality between 1.9-2.1,
Further, add toughness reinforcing component tetrahydrofuran (THF) polyethers or polyoxyethylene glycol.
Further, being calculated as follows of average functionality: bring all substances except that catalyzer in the reaction raw materials into average functionality and calculate; By the reactant of the excessive functional group of functionality contrast judgement, the amount of substance according to inexcessive functional group reactions thing calculates average functionality then.
The method for preparing poly(lactic acid) that the present invention proposes is the polycondensation method of a kind of direct preparation branching or micro-cross-linking polylactic acid, and its step is as follows:
Removal of impurities to material acid is handled
Removal of impurities is handled and is adopted decompression technology.Promptly under appropriate vacuum degree and temperature condition, reduce pressure and remove impurity and moisture.Because the technical grade lactic raw material contains many lower boiling impurity and portion water, adopt reasonably decompression removal of impurities to dewater and necessitate.Follow stirring in the whole removal of impurities process.At first the pressure with system drops to below the 200Pa, can't see small bubbles in system substantially, and this section period is 1-3 hour.With the system heating, control lactic acid vapor temperature is between 30-40 ℃ then, and system pressure 100-200Pa kept 1-4 hour.Can see and not have small bubbles to occur in the system substantially.Take out the lactic acid in the matrass, standby.
1. the polycondensation process gelation is calculated
Judge gelation process according to average functionality in the system, and then control the degree of final polycondensate gel (or crosslinked).Concrete computation process is as follows: 1) all substances except that catalyzer are brought average functionality calculating in the reaction raw materials; 2) by the reactant of the excessive functional group of functionality contrast judgement, the amount of substance according to inexcessive functional group reactions thing calculates average functionality then.As hydroxyl, total amount of substance difference 3.2mol and the 3.06mol of carboxyl in the system, and the total amount of substance of each material of system is assumed to 3mol, amount of substance according to carboxyl calculates average functionality: the amount of substance of carboxyl is taken advantage of 2 again divided by the total amount of substance of system reactant, and getting average functionality is 2.04.Can produce gel (or crosslinked) according to average functionality preliminary judgement system.
2. prepolymerization
To handle the lactic acid that obtains through removal of impurities is raw material, under the condition of catalyzer and the existence of interpolation component, carries out precondensation.
Employed catalyzer is mainly three classes, and the metal of II, III, IV and V family in (1) periodic table of elements is as magnesium, aluminium, titanium, zinc, tin etc.; The oxide compound of the metal of (2) II, III, IV and V family is as magnesium oxide, aluminum oxide, titanium oxide, zinc oxide, tin protoxide, stannic oxide etc.; The salt of the metal of (3) II, III, IV and V family is as stannous octoate, tin protochloride, zinc ethyl, tin acetate, etheric acid aluminium etc.
Used interpolation component is mainly three classes: 1) polyprotonic acid or monoprotic acid are selected from terephthalic acid, m-phthalic acid, adjacent benzene tetracarboxylic acid, 1,4,5,8-naphthalenetetracarbacidic acidic, ethylenediamine tetraacetic acid (EDTA), 3,3,4,4-benzophenone tetracid, propanedioic acid, hexanodioic acid, certain herbaceous plants with big flowers diacid, undecane diprotic acid, dodecane diprotic acid; 2) polyvalent alcohol or monohydroxy-alcohol are selected from ethylene glycol, propylene glycol, 1,3-butyleneglycol, 1,4-butyleneglycol, 2,3-pentanediol, neopentyl glycol, hexylene glycol, 1,10-certain herbaceous plants with big flowers glycol, 18 glycol, glycerol, sorbyl alcohol, polyoxyethylene glycol, tetrahydrofuran (THF) polyethers, tetramethylolmethane; 3) polynary mixing acid alcohol (promptly not only contained carboxyl in molecule but also contained the compound of hydroxyl) is selected from dimethylol propionic acid, citric acid, oxysuccinic acid, tartrate.
In pre-collecting process, temperature of reaction is 120-170 ℃, and more excellent temperature is 120-160 ℃; Reaction times is 3-6 hour.Controlled temperature rises gradually in the reaction process.Can feed other rare gas elementes such as nitrogen in the reaction process, can accelerate dehydration on the one hand, can reduce side reaction on the other hand.
3. condensation polymerization
On the basis of pre-polymerization, continue reaction.Condensation temperature is 160-200 ℃, and more excellent condensation temperature is 170-190 ℃; Vacuum tightness progressively reduces, and hierarchy of control pressure is 1000Pa-10Pa, and more excellent system pressure is 10-200Pa.Reaction times is 3-12 hour, can obtain the poly(lactic acid) that molecular weight is 5-30 ten thousand.
The reaction formula of branching or micro-cross-linking polylactic acid one still process is as follows:
Figure G2009100881925D00031
Branched structure will not only be described main molecules chain backbone structure in expression in the following formula.
The present invention obtains the poly(lactic acid) of higher molecular weight, and greatly reduces production cost by prescription reasonable in design, is a kind of effective poly(lactic acid) direct polycondensation method.
Embodiment
Specifically describe the present invention below by embodiment.
Embodiment 1:
Is furnished with the D that adds in the reactor of temperature control, stirring, nitrogen ingress pipe and vacuum pump through removal of impurities to 1.5L, L-lactic acid 475 grams and tetramethylolmethane 4.4874g, hexanodioic acid 9.6334g, stannous octoate 3.2414g, feed nitrogen 10min, be heated to 150 ℃ and stir dehydration 3 hours down.Temperature is risen to 180 ℃ then, continue to stir, open vacuum pump, progressively reduce system pressure, with the dropping to of system, continue to reduce pressure in two hours until 100Pa to less than 1000Pa.Be 180 ℃ from system temperature and pick up counting that polycondensation discharging in 5 hours obtains weight-average molecular weight and be 58600 poly(lactic acid).
The calculating of system average functionality: 1) lactic acid, 5.27778mol; Tetramethylolmethane, 0.03296mol; Hexanodioic acid, 0.06592mol;
2) average functionality f ‾ = ( 5.27778 + 0.03296 × 4 ) × 2 5.27778 + 0.03296 + 0.06592 = 2.0123
Embodiment 2:
Is furnished with the D that adds in the reactor of temperature control, stirring, nitrogen ingress pipe and vacuum pump through removal of impurities to 1.5L, L-lactic acid 475 grams and tetramethylolmethane 4.4712g, hexanodioic acid 9.6340g, stannous octoate 3.5734g, feed nitrogen 10min, be heated to 150 ℃ and stir dehydration 3 hours down.Temperature is risen to 180 ℃ then, continue to stir, open vacuum pump, progressively reduce system pressure, with the dropping to of system, continue to reduce pressure in two hours until 100Pa to less than 1000Pa.Be 180 ℃ from system temperature and pick up counting that polycondensation discharging in 6 hours obtains weight-average molecular weight and be 78400 poly(lactic acid).
The calculating of system average functionality: 1) lactic acid, 5.27778mol; Tetramethylolmethane, 0.03284mol; Hexanodioic acid, 0.06592mol;
2) average functionality f ‾ = ( 5.27778 + 0.03284 × 4 ) × 2 5.27778 + 0.03284 + 0.06592 = 2.0123
Embodiment 3:
Is furnished with the D that adds in the reactor of temperature control, stirring, nitrogen ingress pipe and vacuum pump through removal of impurities to 1.5L, L-lactic acid 475 grams and tetramethylolmethane 4.4868g, hexanodioic acid 9.6352g, stannous octoate 3.3216g, feed nitrogen 10min, be heated to 150 ℃ and stir dehydration 3 hours down.Temperature is risen to 180 ℃ then, continue to stir, open vacuum pump, progressively reduce system pressure, with the dropping to of system, continue to reduce pressure in two hours until 100Pa to less than 1000Pa.Be 180 ℃ from system temperature and pick up counting that polycondensation discharging in 8 hours obtains weight-average molecular weight and be 125700 poly(lactic acid).
The calculating of system average functionality: 1) lactic acid, 5.27778mol; Tetramethylolmethane, 0.03296mol; Hexanodioic acid, 0.06593mol;
2) average functionality f ‾ = ( 5.27778 + 0.03296 × 4 ) × 2 5.27778 + 0.03296 + 0.06592 = 2.0123
Embodiment 4:
Is furnished with the D that adds in the reactor of temperature control, stirring, nitrogen ingress pipe and vacuum pump through removal of impurities to 1.5L, L-lactic acid 472 grams and tetramethylolmethane 4.4854g, hexanodioic acid 9.6654g, stannous octoate 3.2756g, feed nitrogen 10min, be heated to 150 ℃ and stir dehydration 3 hours down.Temperature is risen to 180 ℃ then, continue to stir, open vacuum pump, progressively reduce system pressure, with the dropping to of system, continue to reduce pressure in two hours until 100Pa to less than 1000Pa.Be 180 ℃ from system temperature and pick up counting that polycondensation discharging in 10 hours obtains weight-average molecular weight and be 154300 poly(lactic acid).Adopt the Soxhlet extracting, recording gel content is 14%.
The calculating of system average functionality: 1) lactic acid, 5.24444mol; Tetramethylolmethane, 0.03295mol; Hexanodioic acid, 0.06614mol;
2) average functionality f ‾ = ( 5.24444 + 0.03295 × 4 ) × 2 5.24444 + 0.03295 + 0.06614 = 2.0122
Embodiment 5:
Is furnished with the D that adds in the reactor of temperature control, stirring, nitrogen ingress pipe and vacuum pump through removal of impurities to 1.5L, L-lactic acid 600g and tetramethylolmethane 6.1368g, hexanodioic acid 13.1790g, stannous octoate 6g, feed nitrogen 10min, be heated to 140 ℃ and stir dehydration 3 hours down.Temperature is risen to 160 ℃ then, continue to stir, open vacuum pump, progressively reduce system pressure, with the dropping to of system, continue to reduce pressure in two hours until 100Pa to less than 1000Pa.Be 160 ℃ from system temperature and pick up counting that polycondensation discharging in 8 hours obtains weight-average molecular weight and be 288700 poly(lactic acid).Adopt the Soxhlet extracting, recording gel content is 20%.
The calculating of system average functionality: 1) lactic acid, 6.66667mol; Tetramethylolmethane, 0.04507mol; Hexanodioic acid, 0.09018mol;
2) average functionality f ‾ = ( 6 . 66667 + 0.04507 × 4 ) × 2 6 . 66667 + 0.04507 + 0.09018 = 2.0132
Embodiment 6:
Is furnished with the D that adds in the reactor of temperature control, stirring, nitrogen ingress pipe and vacuum pump through removal of impurities to 1.5L, L-lactic acid 500g and tetramethylolmethane 5.0132g, hexanodioic acid 10.7570g, stannous octoate 5g, feed nitrogen 10min, be heated to 150 ℃ and stir dehydration 6 hours down.Temperature is risen to 190 ℃ then, continue to stir, open vacuum pump, progressively reduce system pressure, with the dropping to of system, continue to reduce pressure in two hours until 100Pa to less than 1000Pa.Be 190 ℃ from system temperature and pick up counting that polycondensation discharging in 8 hours obtains weight-average molecular weight and be 337200 poly(lactic acid).Adopt the Soxhlet extracting, recording gel content is 23%.
The calculating of system average functionality: 1) lactic acid, 5.55556mol; Tetramethylolmethane, 0.03682mol; Hexanodioic acid, 0.07361mol;
2) average functionality f ‾ = ( 5.55556 + 0.07361 × 2 ) × 2 5.55556 + 0.03682 + 0.07361 = 2.0123
Embodiment 7:
Is furnished with the D that adds in the reactor of temperature control, stirring, nitrogen ingress pipe and vacuum pump through removal of impurities to 1.5L, L-lactic acid 550g and tetramethylolmethane 6.3789g, hexanodioic acid 13.7000g, stannous octoate 5.5g, feed nitrogen 10min, be heated to 120 ℃ and stir dehydration 3 hours down.Temperature is risen to 175 ℃ then, continue to stir, open vacuum pump, progressively reduce system pressure, with the dropping to of system, continue to reduce pressure in two hours until 100Pa to less than 1000Pa.Be 175 ℃ from system temperature and pick up counting that polycondensation discharging in 9 hours obtains weight-average molecular weight and be 294900 poly(lactic acid).Adopt the Soxhlet extracting, recording gel content is 19%.
The calculating of system average functionality: 1) lactic acid, 6.11111mol; Tetramethylolmethane, 0.04685mol; Hexanodioic acid, 0.09375mol;
2) average functionality f ‾ = ( 6 . 11111 + 0.04685 × 4 ) × 2 6 . 11111 + 0.04685 + 0.09375 = 2.0150
Embodiment 8:
Is furnished with the D that adds in the reactor of temperature control, stirring, nitrogen ingress pipe and vacuum pump through removal of impurities to 1.5L, L-lactic acid 600 grams and tetramethylolmethane 6.1434g, hexanodioic acid 13.2132g, stannous octoate 6g, feed nitrogen 10min, be heated to 120 ℃ and stir dehydration 3 hours down.Temperature is risen to 160 ℃ then, continue to stir, open vacuum pump, progressively reduce system pressure, with the dropping to of system, continue to reduce pressure in two hours until 100Pa to less than 1000Pa.Be 160 ℃ from system temperature and pick up counting that polycondensation discharging in 12 hours obtains weight-average molecular weight and be 56700 poly(lactic acid).
The calculating of system average functionality: 1) lactic acid, 6.66667mol; Tetramethylolmethane, 0.04512mol; Hexanodioic acid, 0.09042mol;
2) average functionality f ‾ = ( 6 . 66667 + 0.04512 × 4 ) × 2 6 . 66667 + 0.04512 + 0.09042 = 2.0132
Embodiment 9:
Is furnished with the D that adds in the reactor of temperature control, stirring, nitrogen ingress pipe and vacuum pump through removal of impurities to 1.5L, L-lactic acid 580 grams and tetramethylolmethane 6.8544g, hexanodioic acid 14.7100g, stannous octoate 5.8g, feed nitrogen 10min, be heated to 120 ℃ and stir dehydration 3 hours down.Temperature is risen to 180 ℃ then, continue to stir, open vacuum pump, progressively reduce system pressure, with the dropping to of system, continue to reduce pressure in two hours until 100Pa to less than 1000Pa.Be 180 ℃ from system temperature and pick up counting that polycondensation discharging in 6 hours obtains weight-average molecular weight and be 63700 poly(lactic acid).
The calculating of system average functionality: 1) lactic acid, 6.44444mol; Tetramethylolmethane, 0.05034mol; Hexanodioic acid, 0.10066mol;
2) average functionality f ‾ = ( 6.44444 + 0.10066 × 2 ) × 2 6.44444 + 0.10066 + 0.05034 = 2.0133
Embodiment 10:
Is furnished with the D that adds in the reactor of temperature control, stirring, nitrogen ingress pipe and vacuum pump through removal of impurities to 1.5L, L-lactic acid 620 grams and tetramethylolmethane 6.3482g, hexanodioic acid 14.3468g, stannous octoate 6.2g, feed nitrogen 10min, be heated to 130 ℃ and stir dehydration 3 hours down.Temperature is risen to 160 ℃ then, continue to stir, open vacuum pump, progressively reduce system pressure, with the dropping to of system, continue to reduce pressure in two hours until 100Pa to less than 1000Pa.Be 160 ℃ from system temperature and pick up counting that polycondensation discharging in 12 hours obtains weight-average molecular weight and be 61300 poly(lactic acid).
The calculating of system average functionality: 1) lactic acid, 6.88889mol; Tetramethylolmethane, 0.04663mol; Hexanodioic acid, 0.09817mol;
2) average functionality f ‾ = ( 6.68889 + 0.04663 × 4 ) × 2 6.68889 + 0.04663 + 0.09817 = 2.0119
Example 11:
Is furnished with the D that adds in the reactor of temperature control, stirring, nitrogen ingress pipe and vacuum pump through removal of impurities to 1.5L, L-lactic acid 602 grams and tetramethylolmethane 6.0132g, hexanodioic acid 12.9084g, stannous octoate 7.9536g, feed nitrogen 10min, be heated to 150 ℃ and stir dehydration 3 hours down.Temperature is risen to 180 ℃ then, continue to stir, open vacuum pump, progressively reduce system pressure, with the dropping to of system, continue to reduce pressure in two hours until 100Pa to less than 1000Pa.Be 180 ℃ from system temperature and pick up counting that polycondensation discharging in 8 hours obtains weight-average molecular weight and be 195000 poly(lactic acid).Adopt the Soxhlet extracting, recording gel content is 16%.
The calculating of system average functionality: 1) lactic acid, 6.6889mol; Tetramethylolmethane, 0.04417mol; Hexanodioic acid, 0.088329mol;
2) average functionality f ‾ = ( 6.6889 + 0.088329 × 2 ) × 2 6.6889 + 0.04417 + 0.08839 = 2.0129
Embodiment 12:
Is furnished with the D that adds in the reactor of temperature control, stirring, nitrogen ingress pipe and vacuum pump through removal of impurities to 1.5L, L-lactic acid 652.2 grams and dimethylol propionic acid 6.5092g, hexanodioic acid 10.1268g, stannous octoate 6.5035g, feed nitrogen 30min, be heated to 150 ℃ and stir dehydration 3 hours down.Temperature is risen to 180 ℃ then, continue to stir, open vacuum pump, progressively reduce system pressure, with the dropping to of system, continue to reduce pressure in two hours until 100Pa to less than 1000Pa.Be 180 ℃ from system temperature and pick up counting that polycondensation discharging in 12 hours obtains weight-average molecular weight and be 93000 poly(lactic acid).
The calculating of system average functionality: 1) lactic acid, 7.24666mol; Dimethylol propionic acid, 0.048529mol; Hexanodioic acid, 0.069295mol;
2) average functionality f ‾ = ( 7.24666 + 0.048529 × 2 ) × 2 7.24666 + 0.048529 + 0.069295 = 1.9944
Embodiment 13:
Is furnished with the D that adds in the reactor of temperature control, stirring, nitrogen ingress pipe and vacuum pump through removal of impurities to 1.5L, L-lactic acid 707 grams and dimethylol propionic acid 6.5049g, hexanodioic acid 10.1239g, stannous octoate 6.5315g, feed nitrogen 20min, be heated to 150 ℃ and stir dehydration 3 hours down.Temperature is risen to 180 ℃ then, continue to stir, open vacuum pump, progressively reduce system pressure, with the dropping to of system, continue to reduce pressure in two hours until 100Pa to less than 1000Pa.Be 180 ℃ from system temperature and pick up counting that polycondensation discharging in 12 hours obtains weight-average molecular weight and be 109000 poly(lactic acid).
The calculating of system average functionality: 1) lactic acid, 7.85556mol; Dimethylol propionic acid, 0.048497mol; Hexanodioic acid, 0.069275mol;
2) average functionality f ‾ = ( 7.85556 + 0.048497 × 2 ) × 2 7.85556 + 0.048497 + 0.069275 = 1.9948
Embodiment 14:
Be furnished with the D that adds in the reactor of temperature control, stirring, nitrogen ingress pipe and vacuum pump through removal of impurities to 1.5L, L-lactic acid 652 gram and dimethylol propionic acid 6.5092g, stannous octoate 6.5035g feed nitrogen 30min, are heated to 150 ℃ and stir down and dewatered 3 hours.Temperature is risen to 180 ℃ then, continue to stir, open vacuum pump, progressively reduce system pressure, with the dropping to of system, continue to reduce pressure in two hours until 100Pa to less than 1000Pa.Be 180 ℃ from system temperature and pick up counting that polycondensation 12 hours obtains weight-average molecular weight and be 74000 poly(lactic acid).
The calculating of system average functionality: 1) lactic acid, 7.24444mol; Dimethylol propionic acid, 0.048529mol;
2) average functionality f ‾ = ( 7.24444 + 0.048529 ) × 2 7.24444 + 0.048529 = 2
Embodiment 15:
Is furnished with the D that adds in the reactor of temperature control, stirring, nitrogen ingress pipe and vacuum pump through removal of impurities to 1.5L, L-lactic acid 602 grams and tetramethylolmethane 21.5356g, stannous octoate 6.5035g, hexanodioic acid 32.7530g, tetrahydrofuran (THF) polyethers 30g, feed nitrogen 10-30min, be heated to 160 ℃ and stir dehydration 3 hours down.Temperature is risen to 180 ℃ then, continue to stir, open vacuum pump, progressively reduce system pressure, with the dropping to of system, continue to reduce pressure in two hours until 100Pa to less than 1000Pa.Be 180 ℃ from system temperature and pick up counting that polycondensation discharging in 11 hours obtains weight-average molecular weight and be 53400 poly(lactic acid).Added toughness reinforcing component tetrahydrofuran (THF) polyethers, product fragility has obtained bigger improvement, compares in other prescription, and the product of this prescription is not easy to break off with the fingers and thumb disconnected with hand, and the poly(lactic acid) of not adding toughness reinforcing component is more easily broken off with the fingers and thumb disconnected.
The calculating of system average functionality: 1) lactic acid, 6.68888mol; Tetramethylolmethane, 0.15818mol; Hexanodioic acid 0.22412mol, tetrahydrofuran (THF) polyethers 0.03mol.
2) average functionality f ‾ = ( 6.68888 + 0.22412 × 2 ) × 2 6.68888 + 0.15818 + 0.22412 + 0.03 = 2.0101
Embodiment 16:
Be furnished with the D that adds in the reactor of temperature control, stirring, nitrogen ingress pipe and vacuum pump through removal of impurities to 1.5L, L-lactic acid 472 grams, stannous octoate 3.2756g feeds nitrogen 10min, is heated to 150 ℃ and stirs dehydration 3 hours down.Temperature is risen to 180 ℃ then, continue to stir, open vacuum pump, progressively reduce system pressure, with the dropping to of system, continue to reduce pressure in two hours until 100Pa to less than 1000Pa.Be 180 ℃ from system temperature and pick up counting that polycondensation discharging in 10 hours obtains weight-average molecular weight and be 8400 poly(lactic acid).Clearly this routine average functionality is 2.(this example 16 is blank Comparative Examples, with embodiment 4 contrasts.By the control average functionality, in the presence of interpolation component tetramethylolmethane, the weight-average molecular weight of embodiment 4 increases significantly as can be seen.)

Claims (2)

1. a still prepares the method for branching or micro-cross-linking polylactic acid, it is characterized in that: be furnished with the D that adds in the reactor of temperature control, stirring, nitrogen ingress pipe and vacuum pump through removal of impurities to 1.5L, L-lactic acid 600g and tetramethylolmethane 6.1368g, hexanodioic acid 13.1790g, stannous octoate 6g, feed nitrogen 10min, be heated to 140 ℃ and stir dehydration 3 hours down; Temperature is risen to 160 ℃ then, continue to stir, open vacuum pump, progressively reduce system pressure, the pressure with system in two hours drops to less than 1000Pa, continues to reduce pressure until 100Pa; Be 160 ℃ from system temperature and pick up counting that polycondensation discharging in 8 hours obtains weight-average molecular weight and be 288700 poly(lactic acid); Adopt the Soxhlet extracting, recording gel content is 20%; The average functionality of poly(lactic acid) is 2.0132, and described average functionality is calculated as follows: bring all substances except that catalyzer in the reaction raw materials into average functionality and calculate; By the reactant of the excessive functional group of functionality contrast judgement, the amount of substance according to inexcessive functional group reactions thing calculates average functionality then.
2. a still prepares the method for branching or micro-cross-linking polylactic acid, it is characterized in that: be furnished with the D that adds in the reactor of temperature control, stirring, nitrogen ingress pipe and vacuum pump through removal of impurities to 1.5L, L-lactic acid 500g and tetramethylolmethane 5.0132g, hexanodioic acid 10.7570g, stannous octoate 5g, feed nitrogen 10min, be heated to 150 ℃ and stir dehydration 6 hours down; Temperature is risen to 190 ℃ then, continue to stir, open vacuum pump, progressively reduce system pressure, the pressure with system in two hours drops to less than 1000Pa, continues to reduce pressure until 100Pa; Be 190 ℃ from system temperature and pick up counting that polycondensation discharging in 8 hours obtains weight-average molecular weight and be 337200 poly(lactic acid); Adopt the Soxhlet extracting, recording gel content is 23%; The average functionality of poly(lactic acid) is 2.0123, and described average functionality is calculated as follows: bring all substances except that catalyzer in the reaction raw materials into average functionality and calculate; By the reactant of the excessive functional group of functionality contrast judgement, the amount of substance according to inexcessive functional group reactions thing calculates average functionality then.
CN2009100881925A 2009-07-13 2009-07-13 Method for preparing branching or micro-cross-linking polylactic acid by one kettle Expired - Fee Related CN101585911B (en)

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CN104629026B (en) * 2015-02-15 2016-05-04 东华大学 A kind of biomedical complex crosslinking copolymerization polyester elastomer materials and preparation method thereof
IT201900002891A1 (en) * 2019-02-28 2020-08-28 Bio Valore World S P A Soc Benefit METHOD FOR THE PREPARATION OF LACTIC ACID BRANCHED POLYMERS WITH LOW MELT VISCOSITY
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