CN102584567B - Efficient polylactic acid nucleating agent, and preparation method and application thereof - Google Patents

Efficient polylactic acid nucleating agent, and preparation method and application thereof Download PDF

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CN102584567B
CN102584567B CN201110455345.2A CN201110455345A CN102584567B CN 102584567 B CN102584567 B CN 102584567B CN 201110455345 A CN201110455345 A CN 201110455345A CN 102584567 B CN102584567 B CN 102584567B
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polylactic acid
nucleator
nucleating agent
poly
heat
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CN201110455345.2A
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Chinese (zh)
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CN102584567A (en
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魏志勇
宋平
陈广义
梁继才
张万喜
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大连理工大学
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Abstract

The invention discloses an efficient polylactic acid nucleating agent, and a preparation method and application thereof and belongs to the technical field of crystallization and modification of polylactic acid. The prepared nucleating agent is a lamellar submicron zinc citrate complex, and is generated by heating zinc salt and citric acid in a mixed solution of water and ethanol and performing reflux reaction. A small amount of the nucleating agent and polylactic acid are mixed in advance and then are fused, blended and molded so as to obtain a polylactic acid product which is highly crystallized and has excellent heat resistance. The prepared nucleating agent has high safety for a human body and an obvious nucleating effect; and a process is simple and environment-friendly, the problems of low crystallization rate and heat resistance of the polylactic acid are solved, the forming processability of the polylactic acid product is improved, and a production cycle is shortened.

Description

A kind of efficient polylactic acid nucleating agent and its preparation method and application

Technical field

The invention belongs to the crystalline modified technical field of poly(lactic acid), be specifically related to a kind of efficient polylactic acid nucleating agent and preparation method thereof and its application in heat-proof polylactic acid goods.

Background technology

In recent years, along with a large amount of consumption of petroleum resources and being widely used of petroleum-based plastics, the energy dilemma and the problem of environmental pollution that cause thus become increasingly conspicuous.Consider from the angle of environment protection and Sustainable development, developing reproducible biodegradated polymer materal has become when one of the research of prepolymer novel material important directions very.Wherein, poly(lactic acid) becomes one of the most potential kind because of its outstanding performance.Poly(lactic acid) be utilize reproducible plant resources as the farm crop such as corn, sugarcane, potato, beet be raw material, the starch therefrom extracting is made lactic acid through fermentation, then passes through polycondensation and synthetic aliphatic polyester.Due to taking Biological resources as raw material, break away from the dependence to oil.Poly(lactic acid) can complete biodegradable, and the waste after use is decomposed into carbonic acid gas and water after compost treatment, can not pollute soil.In addition, poly(lactic acid) has good physicals, mechanical property and thermoplasticity, can on general processing units, extrude, the moulding such as injection moulding, blowing, hot pressing and melt-spinning.At present, poly(lactic acid) has been widely used in as numerous areas such as medicine, packaging, disposable product, agricultural buildings.In addition, poly(lactic acid) has also been launched relevant applied research as engineering plastics at the aspect such as electronic apparatus and automotive upholstery.

Although poly(lactic acid) has above-mentioned many merits, the drawbacks limit such as the slow and poor heat resistance of its crystallization rate its practical application.The goods that obtain in traditional injection moulding process are often amorphous state, when temperature reaches its second-order transition temperature (approximately 60 DEG C) when above, easily softening transform, mechanical property also reduces thereupon greatly, and this has restricted its application aspect engineering materials to a great extent.In injection moulding process, in order to realize necessary degree of crystallinity, die temperature can be set in to the crystallizable temperature range (80 DEG C~140 DEG C) of poly(lactic acid), and extend the cooling time (more than 20 minutes) in mould, but the shaping cycle after adopting is in this way long especially, can not meet suitability for industrialized production.Therefore,, in order to expand the practical application of poly(lactic acid), a large amount of research work concentrates on and how to improve the crystallizing power of poly(lactic acid) and improve its thermotolerance.Wherein, add heterogeneous nucleation agent be polymer crystallization and heat resistance modified in the most effective and economical and practical method.Nucleator is divided into inorganic and organic two large classes.Conventional inorganic nucleator has talcum powder, polynite, phosphatic rock, whisker, carbon black etc., but the nucleating effect of this class nucleator is poor, while interpolation on a small quantity, crystallization rate is still lower, when content is higher, easily cause polylactic acid article embrittlement, resistance to impact shock obviously declines.

A kind of rapid nucleating agent of polylactic resin is disclosed in patent CN101423625B, this nucleator is phenyl-phosphonite metal-salt or the phosphinous acid metal-salt that contains three valent phosphors or phosphorus hydrogen bond, can promote the growth of poly(lactic acid) crystal, refinement spherulite size, and there is stronger antioxidant property.Patent JP2010150365A discloses and in poly(lactic acid), has added arylsulphonate, can improve the crystallization velocity of low optical purity poly(lactic acid).Patent CN101857715A discloses a kind of method of quickly crystallizing polylactic acid, wherein utilizes the nucleator as poly(lactic acid) by benzoyl hydrazine and the synthetic bisamide compounds of alkyl two acyl dichloros.Patent CN102020784A discloses a kind of self-assembled calixarene nucleating agent and the application in polylactic acid resin composition thereof, and this nucleator is generated through self-assembly in organic solvent by calixarene, is applied in poly(lactic acid) and can greatly improves its crystallization velocity.Although these organic nucleator nucleating effects are better, all relate to the arene compounds that contains phenyl ring in preparation process, can cause certain harm to human body and environment.Therefore, be necessary to research and develop nucleating agent in polylactic acid production efficient, safe, preparation process environmental protection.

Summary of the invention

The present invention, in order to overcome the deficiencies in the prior art, provides a kind of preparation method of nucleating agent in polylactic acid production of highly effective and safe.

The object of the invention is to be achieved through the following technical solutions:

A kind of preparation method of efficient polylactic acid nucleating agent, it is characterized in that comprising the steps: 0.01~0.02 mole of zinc salt is dissolved in the mixing solutions of 70~100 milliliters of ethanol and 2~5 ml distilled waters, reflux 2~3 hours so that zinc salt is dispersed in 75~85 DEG C of stirred in water bath, then in solution, be within 1: 1~3: 2, to add citric acid by zinc salt and citric acid mol ratio, continue reaction 3~4 hours, after finishing, reaction naturally cools to room temperature, suction filtration, filter cake second alcohol and water repetitive scrubbing three times, obtain white powder after vacuum-drying;

Described zinc salt is zinc acetate, zinc nitrate, zinc carbonate or zinc sulfate; Preferably zinc acetate and zinc nitrate.

A kind of efficient polylactic acid nucleating agent of being prepared by aforesaid method, it is characterized in that this nucleator is a kind of submicron order zinc citrate title complex of sheet, its particle diameter is 0.1~0.3 μ m, has larger specific surface area, nucleation density is high, has evenly good dispersiveness in poly(lactic acid).

In addition, the present invention also provides the method for utilizing the preparation of above-mentioned nucleator to have the poly(lactic acid) moulded product of heat-resisting requirement: by dried nucleator and poly(lactic acid) after high speed mixer is pre-mixed, then carry out melting mixing, granulation with twin screw extruder, after super-dry, finally carry out molded with injection moulding machine.In injection moulding process, die temperature is set as 90~120 DEG C, and be 1~3 minute cooling time.When cooling time is during lower than 1 minute, crystallization may be insufficient; When cooling time is during higher than 3 minutes, the productivity of goods can reduce.

For the lower goods of dimension precision requirement, can not adopt the method for heating mould, but the profiled member obtaining after injection moulding, need be under the condition of 90~120 DEG C, annealing thermal treatment 1~3 minute.

The optical purity of the poly(lactic acid) in above-mentioned application should be greater than 95%, and number-average molecular weight is 50,000~150,000.The too low poly(lactic acid) of optical purity has almost been lost crystallizing power.Molecular weight is too small, and the poor mechanical property of goods does not possess use properties; Molecular weight is too high, and melting index is large, machine-shaping difficulty, and also molecular weight is higher, and the crystallizing power of poly(lactic acid) is also poorer.The addition of nucleator is 0.05%~5% of nucleator and poly(lactic acid) total mass, is preferably 0.2%~1%.The selection of this scope both can realize the rapid crystallization of poly(lactic acid), crystal grain thinning, can avoid again addition too high cause become fragile and resistance to impact shock under degradation defect.

Compared with prior art, tool of the present invention has the following advantages:

(1) simple, the Yi Hang of nucleator preparation method of the present invention, environmental protection, because zinc citrate is a kind of conventional organic zinc supplementation agent and foodstuff additive, therefore, the zinc citrate complex nucleating agent making has the security of height to human body;

(2) nucleating effect is remarkable, and the interpolation of a small amount of nucleator can realize the rapid crystallization of poly(lactic acid), and crystal grain thinning, reaches the object that completes at short notice crystallization.

(3) nucleator of the present invention is applied in poly(lactic acid), can improve thermotolerance and the forming process type of poly(lactic acid) moulded product, has shortened the process for processing cycle.

Brief description of the drawings

3, the total accompanying drawing of the present invention, wherein:

Fig. 1 is the transmission electron microscope photo of sheet zinc citrate title complex;

Fig. 2 is that embodiment and comparative example are schemed with the cooling DSC of 10 DEG C/min;

Fig. 3 is the DSC figure of embodiment and comparative example isothermal crystal at 130 DEG C.

Embodiment

Below by specific embodiment and comparative example, the present invention is further illustrated, but the present invention is not limited to these embodiment.

Embodiment 1

Utilize zinc acetate to prepare the method for zinc citrate complex nucleating agent: 2.20g (0.01 mole) zinc acetate is dissolved in the mixing solutions of 75 milliliters of ethanol and 3 ml distilled waters, reflux 3 hours in 80 DEG C of stirred in water bath, then in solution, add 2.10g (0.01 mole) citric acid, continue reaction 3.5 hours, after finishing, reaction naturally cools to room temperature, ethanol and water washing 3 times for suction filtration, filter cake, after dry, obtain white powder, fusing point (decomposition temperature) is 307 DEG C.

By the nucleator of above-mentioned preparation and poly(lactic acid) (number-average molecular weight is 9.3 ten thousand) at 70 DEG C of vacuum drying ovens dry 10 hours.In mass parts, get 99.8 parts of poly(lactic acid) and 0.2 portion of nucleator, after high speed mixer is pre-mixed, then carry out melting mixing, granulation with SHJ-20 type twin screw extruder.Five sections of Heating temperatures of forcing machine are set as respectively 170,180,185,185,180 DEG C, and head temperature is set as 175 DEG C.The poly (lactic acid) composition obtaining, then through 70 DEG C, vacuum after dry 10 hours, is finally undertaken moldedly by XTK1200 type injector, three sections of temperature of injection moulding machine cartridge heater are set as respectively 175,185,180 DEG C.

The test of crystallization parameters and heat-drawn wire: by the crystallization parameters of the poly (lactic acid) composition after DSC test blending extrusion, temperature control program is in two kinds of situation: (1) is heated to 190 DEG C with 50 DEG C/min from room temperature by sample, insulation 5min is to eliminate thermal history, then with 10 DEG C/min cool to room temperature, record the Tc T in temperature-fall period cwith crystallization enthalpy Δ H c, test result is as shown in Fig. 1 and table 1; (2) sample is heated to 190 DEG C with 50 DEG C/min from room temperature, insulation 5min, to eliminate thermal history, is then cooled to rapidly 130 DEG C to carry out isothermal crystal with 60 DEG C/min, records flexible chain t 1/2, test result as shown in Figure 2 and Table 1.Before test underload (0.45MPa) heat-drawn wire, first, by injection moulding batten anneal 2min in 120 DEG C of baking ovens, batten is of a size of 80mm × 10mm × 4mm, and test result is in table 1.

Embodiment 2

Weigh the nucleator of preparation in 99.5 parts of poly(lactic acid) (number-average molecular weight is 9.3 ten thousand) and 0.5 part of above-described embodiment 1, same melting mixing and injection molding process in experience embodiment 1, test crystallization parameters and heat-drawn wire, the results are shown in Figure 1, Fig. 2 and table 1.

Embodiment 3

Weigh the nucleator of preparation in 99 parts of poly(lactic acid) (number-average molecular weight is 9.3 ten thousand) and 1 part of above-described embodiment 1, same melting mixing and injection molding process in experience embodiment 1, test crystallization parameters and heat-drawn wire, the results are shown in Figure 1, Fig. 2 and table 1.

Embodiment 4

Utilize zinc nitrate to prepare the method for zinc citrate complex nucleating agent: 5.95g (0.02 mole) zinc nitrate is dissolved in the mixing solutions of 95 milliliters of ethanol and 5 ml distilled waters, reflux 2 hours in 80 DEG C of stirred in water bath, then in solution, add 4.20g (0.02 mole) citric acid, continue reaction 3.5 hours, after finishing, reaction naturally cools to room temperature, ethanol and water washing 3 times for suction filtration, filter cake, after dry, obtain white powder, fusing point (decomposition temperature) is 315 DEG C.

Weigh the nucleator of 99.5 parts of poly(lactic acid) (number-average molecular weight is 9.3 ten thousand) and 0.5 part of above-mentioned preparation, same melting mixing and injection molding process in experience embodiment 1, test crystallization parameters and heat-drawn wire, the results are shown in Figure 1, Fig. 2 and table 1.

Embodiment 5

Weigh the nucleator of preparation in 99 parts of poly(lactic acid) (number-average molecular weight is 9.3 ten thousand) and 1 part of above-described embodiment 4, same melting mixing and injection molding process in experience embodiment 1, test crystallization parameters and heat-drawn wire, the results are shown in Figure 1, Fig. 2 and table 1.

Comparative example 1

Pure poly(lactic acid) (number-average molecular weight is 9.3 ten thousand) experiences melting mixing and injection molding process in above-described embodiment 1 too, and test crystallization parameters and heat-drawn wire the results are shown in Figure 1, Fig. 2 and table 1.

Comparative example 2

Weigh 99 parts of poly(lactic acid) (number-average molecular weight is 9.3 ten thousand) and 1 part of talcum powder, same melting mixing and injection molding process in experience above-described embodiment 1, test crystallization parameters and heat-drawn wire, the results are shown in Figure 1, Fig. 2 and table 1.

Comparative example 3

Weigh 99 parts of poly(lactic acid) (number-average molecular weight is 9.3 ten thousand) and 1 part of commercially available zinc citrate, same melting mixing and injection molding process in experience above-described embodiment 1, test crystallization parameters and heat-drawn wire, the results are shown in Figure 1, Fig. 2 and table 1.

The crystallization of table 1 embodiment and comparative example and thermotolerance parameter

Tc T cwith crystallization enthalpy Δ H chigher, flexible chain t 1/2shorter, the crystallization velocity of poly(lactic acid) is faster, and the effect of nucleator is better.From Fig. 1, Fig. 2 and table 1, can find out,, there is not crystallization in the pure non-constant of poly(lactic acid) crystallizing power in 10 DEG C/min process of cooling, and in the isothermal process at 130 DEG C, flexible chain exceedes 40min; Talcum powder and commercially available zinc citrate all have certain nucleogenesis, but nucleating effect is obviously inferior to zinc citrate complex nucleating agent of the present invention.Add this small amount of nucleator and can make quickly crystallizing polylactic acid, the heat-drawn wire of moulded product can reach 120 DEG C of left and right.

Claims (8)

1. the preparation method of an efficient polylactic acid nucleating agent, it is characterized in that comprising the steps: 0.01~0.02 mole of zinc salt is dissolved in the mixing solutions of 70~100 milliliters of ethanol and 2~5 ml distilled waters, reflux 2~3 hours so that zinc salt is dispersed in 75~85 DEG C of stirred in water bath, then in solution, be that 1:1~3:2 adds citric acid by zinc salt and citric acid mol ratio, continue reaction 3~4 hours, after finishing, reaction naturally cools to room temperature, suction filtration, filter cake second alcohol and water repetitive scrubbing three times, obtain white powder after vacuum-drying;
Described zinc salt is zinc acetate or zinc nitrate.
2. an efficient polylactic acid nucleating agent of being prepared by method described in claim 1, is characterized in that this nucleator is the submicron order zinc citrate title complex of sheet, and its particle diameter is 0.1~0.3 μ m.
3. an efficient polylactic acid nucleating agent as claimed in claim 2 application in heat-proof polylactic acid goods, the preparation method who it is characterized in that heat-proof polylactic acid moulded product is: by dried nucleator and poly(lactic acid) after high speed mixer is pre-mixed, carry out melting mixing, granulation with twin screw extruder, after super-dry, carry out molded with injection moulding machine.
4. nucleator according to claim 3 is applied in heat-proof polylactic acid goods, it is characterized in that carrying out die temperature in molded process with injection moulding machine is set as 90~120 DEG C, and be 1~3 minute cooling time.
5. nucleator according to claim 3 is applied in heat-proof polylactic acid goods, it is characterized in that the goods lower for dimension precision requirement, can not adopt the method for heating mould, but the profiled member obtaining after injection moulding, need be under the condition of 90~120 DEG C, annealing thermal treatment 1~3 minute.
6. nucleator according to claim 3 is applied in heat-proof polylactic acid goods, it is characterized in that the optical purity of poly(lactic acid) is greater than 95%, and number-average molecular weight is 50,000~150,000.
7. nucleator according to claim 3 is applied in heat-proof polylactic acid goods, it is characterized in that the quality of described nucleator accounts for 0.05%~5% of nucleator and poly(lactic acid) total mass.
8. nucleator according to claim 7 is applied in heat-proof polylactic acid goods, it is characterized in that the quality of described nucleator accounts for 0.2%~1% of nucleator and poly(lactic acid) total mass.
CN201110455345.2A 2011-12-29 2011-12-29 Efficient polylactic acid nucleating agent, and preparation method and application thereof CN102584567B (en)

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DE4325879C3 (en) * 1993-08-02 1999-05-20 Depron Bv Film of a thermoplastic synthetic foam, process for their preparation and their use
US6417294B1 (en) * 1995-12-21 2002-07-09 Mitsui Chemicals, Inc. Films and molded articles formed from aliphatic polyester compositions containing nucleating agents
DE602007011770D1 (en) * 2006-07-26 2011-02-17 Mitsui Chemicals Inc Thermoplastic composition and form body thereof
US8268918B2 (en) * 2007-06-29 2012-09-18 Unitika Ltd. Crystalline polylactic acid resin composition and product molded/formed therefrom
CN101245159A (en) * 2008-03-28 2008-08-20 天津市润达塑料包装有限公司 Process for manufacturing polyolefin foaming particle material
JP2010150365A (en) * 2008-12-25 2010-07-08 Takemoto Oil & Fat Co Ltd Crystal nucleus agent for polylactic acid resin, and polylactic acid resin composition
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