CN104262917A - Preparation method of high-molecular polylactic acid (PLA) three-dimensional composite material capable of being crystallized rapidly - Google Patents

Abstract

The invention relates to the technical field of modification of bio-based polymer materials, and aims to provide a method for preparing a rapidly crystallizable high-molecular-weight polylactic acid stereocomplex material. The preparation method of the rapidly crystallizable high molecular weight polylactic acid stereocomplex material, the specific preparation steps include: taking the polylactic acid matrix and the organometallic phosphonate nucleating agent and adopting solution or melt blending to obtain the rapidly crystallizable high Molecular weight polylactic acid stereocomposite material. The present invention uses organometallic phosphonate to promote the stereocomplex crystallization of high molecular weight PLLA/PDLA blends, inhibits its homogeneous crystallization, greatly improves the stereocomplex crystallization speed and crystallinity of the blend, and its stereocomplex crystallization The crystallinity of PLA can reach more than 40%, which effectively improves the processability, heat resistance and mechanical properties of PLLA/PDLA blends, and also improves the solvent resistance and degradation resistance of PLA.

Description

Preparation method of high molecular weight polylactic acid stereocomplex material capable of rapid crystallization

technical field

The invention relates to the technical field of modification of bio-based polymer materials, in particular to a method for preparing a rapidly crystallizable high-molecular-weight polylactic acid stereocomplex material.

Background technique

Polylactic acid (PLA) is a typical biodegradable bio-based polymer material, which has good biodegradability, biocompatibility, processability, mechanical properties, etc., and has been widely used in biomedical engineering, packaging materials, Disposable plastic products, textile fibers, films and other fields. However, as a semi-crystalline thermoplastic polyester, PLA has a slow crystallization rate and low crystallinity, which seriously affects its processability and heat resistance, restricting the application of PLA in the industrial field. Stereoregular PLA has two optical isomers, namely L-polylactic acid (PLLA) and D-polylactic acid (PDLA). When PLLA and PDLA are blended, a stereocomplex crystal can be formed, and its melting point is as high as 230°C, which is about 50°C higher than the homogeneous crystal of PLLA or PDLA alone. The overall properties of PLA stereocomposite crystalline materials are similar to those of engineering plastics such as PET and nylon; compared with homogeneous crystalline materials, stereocomposite crystalline materials have higher strength, modulus, and excellent solvent resistance and hydrolysis resistance, so stereocomposite Composite crystallization is an effective way to improve the comprehensive properties of PLA, such as heat resistance. How to effectively improve the rate and crystallinity of PLA stereocomposite crystallization is of great significance to broaden the industrial application fields of bio-based PLA.

However, in the PLLA/PDLA blend system, there is competition between homogeneous crystallization and stereocomplex crystallization. When the molecular weight of PLLA and PDLA is large (weight average molecular weight > 40kg/mol), it is difficult to form stereocomplex crystals with high melting points. , and mainly form homogeneous crystals with low melting points, which has become a bottleneck in the preparation of high heat-resistant PLA stereocomposite materials. Therefore, one of the key technologies in the preparation of high heat-resistant PLA stereocomposite materials is how to selectively promote its stereocomplex crystallization, inhibit its homogeneous crystallization, and how to increase the speed of stereocomplex crystallization. Adding a nucleating agent is a commonly used method in industry to accelerate crystallization, increase crystallinity and adjust crystal form. The nucleating agent plays the role of heterogeneous nucleation in the process of polymer crystallization, which can reduce the crystallization interface free energy of semi-crystalline polymers, make the polymer molecular chains adsorb on its surface to form crystal nuclei, and improve the formation of polymers. Nucleus density, thereby increasing the crystallization rate and crystallinity of the polymer. In addition, based on the epigenetic crystallization mechanism of the nucleating agent surface, the nucleating agent crystals usually match the polymer lattice structure in a certain direction, so the addition of the nucleating agent can also regulate the crystal structure of the polymer.

Organometallic phosphonates are a class of commonly used nucleating agents, patents (such as international patent WO 2005/097894A1, Chinese patent CN 101423625B) and papers (Pan et al., ACS Appl.Mater.Interfaces, 2009,1,402-411) have reported Organometallic phosphonates can promote the homogeneous crystallization of PLLA, and significantly increase the speed and crystallinity of homogeneous crystallization, but the melting point of the material prepared by this method is only 160-170°C, and the heat distortion temperature is usually lower than 110°C , can not meet the needs of high heat-resistant occasions. Since the homogeneous crystals of PLLA or PDLA (such as the α crystal form) are completely different from the crystal structure of the PLLA/PDLA stereocomplex crystal, the nucleating agent of the PLLA homocrystal usually has no obvious nucleation for the stereocomplex crystal of PLLA/PDLA Effect. For the PLLA/PDLA blend system, US Patent US2008/0097074A1 reported that aromatic urea compounds can selectively promote the stereocomplex crystallization between PLLA and PDLA; Urayama et al. (Polymer, 2003, 44, 5635–5641) reported that the Phosphonate complexes can accelerate the stereocomplex crystallization of PLLA/PDLA blends. However, these nucleating aids have complex chemical structures, are difficult to synthesize, and have high preparation costs, which affect their large-scale application.

Contents of the invention

The main purpose of the present invention is to overcome the deficiencies in the prior art, to provide a method for preparing stereocomplex crystallization speed, high crystallinity, easy processing, low production cost, high molecular weight, high heat-resistant polylactic acid stereocomposite material . In order to solve the problems of the technologies described above, the solution of the present invention is:

Provide a preparation method for a high-molecular-weight polylactic acid stereocomplex material capable of rapid crystallization, including the use of an organometallic phosphonate nucleating agent. The specific preparation steps include: taking a polylactic acid matrix, using a solution of an organometallic phosphonate nucleating agent, or Melt blending can obtain high-molecular-weight polylactic acid stereocomposite materials that can be rapidly crystallized;

Among them, the mass of the organometallic phosphonate nucleating agent accounts for 0.1% to 3% of the total composition, the mass of the polylactic acid matrix accounts for 99.9 to 97% of the total composition, and the sum of the mass percentages of each component is 100%; The polylactic acid matrix refers to the left-handed polylactic acid (PLLA) and the right-handed polylactic acid (PDLA), and in the polylactic acid matrix, the mass percentage of the left-handed polylactic acid is 50% to 90%, and the mass percentage of the right-handed polylactic acid is 10%. ~50%;

The organometallic phosphonate nucleating agent is any one of phenyl metal phosphonate, phenyl metal phosphinate or diphenyl metal phosphonate.

In the present invention, when the solution blending method is used for preparation, the specific method is: take L-polylactic acid, D-polylactic acid, and organometallic phosphonate nucleating agent, dissolve them in a volatile solvent, and the concentration of the polymer solution is 50g/L, after stirring and mixing evenly, cast the polymer solution in a polytetrafluoroethylene petri dish, then completely volatilize the volatile solvent at room temperature, and then put the polytetrafluoroethylene petri dish into a vacuum oven at 60°C After drying for 6 hours, a rapidly crystallizable high-molecular-weight polylactic acid stereocomplex material is obtained.

In the present invention, the volatile solvent is dichloromethane or chloroform.

In the present invention, when the melt blending method is used for preparation, the specific method is: take L-polylactic acid, D-polylactic acid, and organometallic phosphonate nucleating agent and add them to an extruder (single-screw extruder or twin-screw extruder) machine), and then kneaded at 230°C for 3 minutes, and then extruded and pelletized to obtain a rapidly crystallizable high-molecular-weight polylactic acid stereocomplex material.

In the present invention, when the melt blending method is used for preparation, carbodiimide antihydrolysis agent and hindered phenolic antioxidant can also be added in the extruder.

In the present invention, the structural formula of the phenyl metal phosphate is:

Wherein, M is a divalent metal.

In the present invention, the structural formula of the phenyl metal phosphinate is:

Wherein, M is a divalent metal.

In the present invention, the structural formula of the diphenyl metal phosphonate is:

Wherein, M is a divalent metal.

In the present invention, the M is at least one divalent metal (preferably zinc) among zinc, barium, and calcium.

In the present invention, the weight-average molecular weight of the L-polylactic acid and the D-polylactic acid is greater than 80kg/mol, and the optical purity is greater than 95%; the particle size of the organometallic phosphonate nucleating agent is between 10 and 30 microns .

In the present invention, the specific preparation steps of PDLA are as follows: 50g D-lactide, 0.08g lauryl alcohol and 0.05g stannous octoate are dried and added to the flask, protected by argon, and reacted at 130°C for 5h to obtain the polymer product .

In the present invention, the preparation method of zinc phenylphosphonate (PPZn), calcium phenylphosphonate (PPCa) and barium phenylphosphonate (PPBa) is as follows: 100g phenylphosphonic acid is dissolved in 2.0L deionized water, Then add an equimolar amount of ZnCl ₂ , CaCl ₂ or BaCl ₂ , stir, adjust the pH value to 5-6 with 5M NaOH aqueous solution, filter and dry to obtain the product.

In the present invention, the preparation method of diphenylphosphonic acid zinc (DPPZn) is as follows: dissolve 10 g of diphenylphosphonic acid in 100 mL of deionized water, add ZnCl ₂ of 1/2 molar amount, adjust the pH with 5M NaOH aqueous solution The value is between 5 and 6, filtered and dried to obtain the product. Among them, if ZnCl ₂ is replaced by CaCl ₂ or BaCl ₂ , DPPCa and DPPBa can be prepared respectively.

In the present invention, the preparation method of phenylphosphinic acid zinc (PP3Zn) is as follows: 10g of phenylphosphinic acid is dissolved in 100mL of deionized water, ZnCl ₂ is added in 1/2 molar amount, and the pH is adjusted with 5M NaOH aqueous solution The value is between 5 and 6, filtered and dried to obtain the product. Among them, if ZnCl ₂ is replaced by CaCl ₂ or BaCl ₂ , PP3Ca and PP3Ba can be prepared respectively.

Compared with prior art, the beneficial effect of the present invention is:

1. The present invention uses organometallic phosphonate to promote the stereocomplex crystallization of high molecular weight PLLA/PDLA blends, inhibits its homogeneous crystallization, greatly improves the stereocomplex crystallization speed and crystallinity of the blend, and its stereo The crystallinity of the composite crystal can reach more than 40%, which effectively improves the processability, heat resistance and mechanical properties of the PLLA/PDLA blend, and also improves the solvent resistance and degradation resistance of PLA;

2. The crystallization nucleating agent in the present invention is an organometallic phosphonate with a particle size between 10 and 30 microns, which has good compatibility with the PLA matrix, is easy to disperse evenly in the matrix, and improves the nucleation effect;

3. The organometallic phosphonate compound in the present invention can be prepared in one step by metathesis reaction, has good thermal stability, can be mixed with polymer matrix by melting or solution method, has simple process and low cost, and can realize large-scale industrial production.

Description of drawings

Figure 1 is the DSC curves of Examples 1-4, Example 6 and Comparative Example 1 during the cooling process at 10°C/min.

Figure 2 is the DSC curves of Examples 1-4, Example 6 and Comparative Example 1 during the 10°C/min heating process after 10°C/min cooling.

Fig. 3 is the DSC curve of Example 10 during the 10°C/min temperature drop and the subsequent 10°C/min temperature rise.

Fig. 4 is the isothermal melting crystallization DSC curves of Examples 1, 10 and Comparative Example 1 at 140°C.

Fig. 5 is the WAXD curve measured after the isothermal melt crystallization of Example 1 and Comparative Example 1 under the condition of 140°C.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment the present invention is described in further detail:

A method for preparing a rapidly crystallizable high-molecular-weight polylactic acid stereocomplex material, which selectively promotes the stereocomplex crystallization of PLLA/PDLA by adding an organometallic phosphonate nucleating agent to the high-molecular-weight PLLA/PDLA blend system , improve the speed and crystallinity of its three-dimensional complex crystallization, and improve the heat resistance of the material. Using this method, only about 1 wt% of nucleating agent is added to obtain a heat-resistant polylactic acid material with a high content of three-dimensional complex crystallization.

A method for preparing a rapidly crystallizable high molecular weight polylactic acid stereocomplex material, the specific preparation steps include: taking PLLA, PDLA, and an organometallic phosphonate nucleating agent, and adopting solution or melt blending to obtain a rapidly crystallizable high Molecular weight polylactic acid stereocomposite material; wherein, the mass of the organometallic phosphonate nucleating agent accounts for 0.1% to 3% of the total composition, the mass of the polylactic acid matrix accounts for 99.9 to 97% of the total composition, and the mass percentage of each component The sum is 100%; the mass percentage of PLLA in the polylactic acid matrix is 50% to 90%, and the mass percentage of PDLA is 10% to 50%. The solution and melt blending method of PLLA, PDLA and crystallization nucleating agent in the present invention are not particularly limited, and known methods can be used.

When using the solution blending method to prepare, the specific method is: take L-polylactic acid, D-polylactic acid, and organometallic phosphonate nucleating agent, dissolve them in volatile solvents such as methylene chloride or chloroform, and the concentration of the polymer solution is 50g/L, after stirring and mixing evenly, cast the polymer solution in a polytetrafluoroethylene petri dish, then completely volatilize the volatile solvent at room temperature, and then put the polytetrafluoroethylene petri dish into a vacuum oven at 60°C After drying for 6 hours, a rapidly crystallizable high-molecular-weight polylactic acid stereocomplex material is obtained.

When using the melt blending method to prepare, the specific method is: take L-polylactic acid, D-polylactic acid, and an organometallic phosphonate nucleating agent and add them to an extruder (single-screw extruder or twin-screw extruder), and then Mixing at 230° C. for 3 minutes, and then extruding and cutting into pellets, a high-molecular-weight polylactic acid stereocomplex material capable of rapid crystallization can be obtained. Among them, carbodiimide antihydrolysis agent and hindered phenolic antioxidant can also be added in the extruder.

The weight-average molecular weights of the L-polylactic acid and the D-polylactic acid are both greater than 80kg/mol, and the optical purity is greater than 95%.

The organometallic phosphonate nucleating agent adopts any one of phenyl metal phosphonate, phenyl metal phosphinate or diphenyl metal phosphonate, and the organometallic phosphonate nucleating agent The particle size is between 10 and 30 microns.

The structural formula of phenyl metal phosphate is:

Wherein, M is a divalent metal, including one or more of zinc, barium, calcium, etc., and it is further preferred to find that zinc salt has the best effect.

The structural formula of phenyl metal phosphinate is:

Wherein, M is a divalent metal, including one or more of zinc, barium, calcium, etc., and it is further preferred to find that zinc salt has the best effect.

The structural formula of diphenyl metal phosphonate is:

Wherein, M is a divalent metal, including one or more of zinc, barium, calcium, etc., and it is further preferred to find that zinc salt has the best effect.

The following examples can enable those skilled in the art to understand the present invention more comprehensively, but do not limit the present invention in any way.

The PLLA used in the examples of the present invention is produced by Shimazu Corporation of Japan, with a number average molecular weight of 116 kg/mol and a weight average molecular weight of 198 kg/mol.

The PDLA used is self-made by ring-opening polymerization of D-lactide, and its number average molecular weight is 190kg/mol, and its weight average molecular weight is 298kg/mol. The specific preparation steps are as follows: 50g D-lactide (purchased from Prak), 0.08g lauryl alcohol (purchased from Amethyst Chemical Co.) and 0.05g stannous octoate were dried and added to the flask, protected by argon, at 130°C Under reaction for 5h, the polymer product was obtained.

Carbodiimide anti-hydrolysis agent (model TMP-2000) and hindered phenolic heat stabilizer were provided by Hangzhou Ximao New Material Technology Co., Ltd.

Nucleating agent phenylphosphonate zinc (PPZn), nucleating agent phenylphosphonate calcium (PPCa) and phenylphosphonate barium (PPBa) reference (ACS Appl.Mater.Interfaces 2009,1,402-411) preparation, specific The method is as follows: Dissolve 100 g of phenylphosphonic acid (purchased from Qingdao Fuslin Chemical Technology Co., Ltd.) in 2.0 L of deionized water, then add equimolar amounts of ZnCl ₂ , CaCl ₂ or BaCl ₂ , stir, and adjust with 5M NaOH aqueous solution. When the pH value is between 5 and 6, filter and dry to obtain the product.

The preparation method of diphenylphosphonic acid zinc (DPPZn) is as follows: dissolve 10 g of diphenylphosphonic acid (purchased from TCI) in 100 mL of deionized water, add 1/2 molar amount of ZnCl ₂ , adjust the pH with 5M NaOH aqueous solution The value is between 5 and 6, filtered and dried to obtain the product.

The preparation method of zinc phenylphosphinate (PP3Zn) is as follows: dissolve 10 g of phenylphosphinic acid (purchased from TCI) in 100 mL of deionized water, add 1/2 molar amount of ZnCl ₂ , adjust the pH with 5M NaOH aqueous solution The value is between 5 and 6, filtered and dried to obtain the product.

Embodiment 1～7 is prepared by solution method blending

The mass percentage of the polylactic acid matrix is 99%, and the mass percentage of different types of nucleating agents is 1%. PLLA, PDLA and nucleating agent were weighed according to the composition mass ratio in Table 1, and then dissolved in chloroform, the concentration of the polymer solution was 50g/L, stirred to make it evenly mixed, and then cast in a polytetrafluoroethylene petri dish, The solvent was completely evaporated at room temperature, and then dried in a vacuum oven at 60 °C for 6 h. Wherein, if chloroform is replaced by dichloromethane, the preparation of this embodiment can also be completed.

Embodiment 8 is prepared by melt blending

The mass percentage of the polylactic acid matrix is 99%, and the mass percentage of the nucleating agent is 1%. Premix 49.5 parts by mass of PLLA, 49.5 parts by mass of PDLA, and 1 part by mass of PPZn according to the composition and mass ratio in Table 1, and then add them to the HAAKE MiniLabII twin-screw mixer, knead at 230°C for 3 minutes, and then extrude and pelletize.

In order to further illustrate the nucleating effect of the nucleating agent in the blend system of equal amounts of PLLA and PDLA, in Comparative Example 1, only the same amount of PLLA and PDLA were blended by solution method. Weigh 50 parts by mass of PLLA and 50 parts by mass of PDLA according to the composition and mass ratio in Table 1. In the solution chloroform, the concentration of the polymer solution is 50g/L, stir to make it evenly mixed, and then cast it on a polytetrafluoroethylene petri dish The solvent was completely evaporated at room temperature, and then dried in a vacuum oven at 60 °C for 6 h.

Test of crystallization behavior: using DSC test, nitrogen atmosphere. In the non-isothermal melting crystallization test, the sample was heated from room temperature to 250°C at 50°C/min, kept for 2 minutes to eliminate the heat history, then cooled to 0°C at 10°C/min, kept at 0°C for 3 minutes, and then heated at 10°C /min to 250°C. In the isothermal melt crystallization test, the sample was heated from room temperature to 250°C at 50°C/min, kept for 2 minutes to eliminate the thermal history, then rapidly cooled to 140°C at 100°C/min, kept for 60 minutes to completely crystallize the polymer, and then heated for 10 °C/min to raise the temperature to 250 °C.

Calculation of crystallization kinetics and thermal performance parameters: During the 10°C/min cooling process, the peak temperature of the crystallization exothermic peak is the melting crystallization temperature (T _mc ), and the integrated area is the melting crystallization enthalpy (△H _mc ). During the 10°C/min heating process after non-isothermal melting crystallization or isothermal crystallization, the peak temperature of the exothermic peak of cold crystallization is the cold crystallization temperature (T _cc ), and the integrated area is the cold crystallization enthalpy (△H _cc ); from 160°C to The endothermic peak at 190°C is the melting peak of homogeneous crystals of PLLA and PDLA, the peak temperature is the melting point of homogeneous crystals (T _m,hc ), and the integral area is the melting enthalpy of homogeneous crystals (△H _m,hc ). The endothermic peak between 190°C and 250°C is the melting peak of the stereocomplex crystal of the PLLA/PDLA blend, the peak temperature is the melting point of the stereocomplex crystal (T _{m, sc} ), and the integral area is the enthalpy of the stereocomplex crystal (△H _{m, sc} ). The relative fraction of the stereocomplex (f _sc ) is calculated by the formula f _sc =△H _m,sc /(△H _m,sc +△H _m,hc ). Based on the data of isothermal crystallization, the half-crystallization time (t0.5) was calculated by the Avrami equation. For the specific method, refer to the literature ACS Applied Materials & Interfaces, 2009, 1, 402-411.

The crystal structure and crystal form of the blends were analyzed by wide-angle X-ray diffractometer (WAXD). The PLLA/PDLA blends with and without nucleating agents were melted in a hot press at 250 °C for 2 min to eliminate the heat history, pressed into thin slices of a certain thickness, and then quickly transferred to an oven at 140 °C for isothermal crystallization for 1 h. Crystallization was complete, and the crystallized flakes were subjected to WAXD analysis.

The spherulite density was observed by polarizing microscope (POM). The PLLA/PDLA blends with and without nucleating agent were melted on a hot stage at 250 °C for 2 min, then rapidly cooled to 140 °C, and left for 1 h to completely crystallize. After crystallization, the spherulite morphology was observed by POM.

The storage modulus of the material at different temperatures was analyzed using a dynamic mechanical property tester. The PLLA/PDLA blends with and without nucleating agents were melted and crystallized isothermally at 140°C, and then cut into thin slices of 15×6×0.5 mm ³ for dynamic mechanical properties testing.

Table 1: Thermal performance parameters of PLLA/PDLA modified by different nucleating agents and unmodified PLLA/PDLA blends in non-isothermal melt crystallization

It can be seen from Table 1 that compared with the unmodified PLLA/PDLA blend (Comparative Example 1), the crystallization speed was accelerated after the addition of an organometallic phosphonate nucleating agent, and it could be completely crystallized during the cooling process of 10 °C/min. Afterwards, cold crystallization does not occur during the heating process, and the three-dimensional composite crystal content increases simultaneously (Fig. 1, Fig. 2). Preferably, it is found that PPZn (Example 1) has the best effect, and a high-melting point stereocomplex crystal is completely formed after adding 1 wt%. Comparing Example 1 and Example 8, it is found that the blending method has no significant effect on the crystallization behavior, and the thermal performance parameters of the modified PLLA/PDLA blends using solution blending and melt blending are basically the same.

Examples 9-11

PLLA, PDLA are blended in equal amounts, and the amount of nucleating agent PPZn is different. PLLA, PDLA and nucleating agent are weighed according to the composition mass ratio in Table 2, respectively, and then dissolved in chloroform. The concentration of the polymer solution is 50g/L. The mixture was mixed evenly, and then cast into a polytetrafluoroethylene petri dish, and the solvent was completely evaporated at room temperature, and then dried in a vacuum oven at 60°C for 6 hours. DSC was used to test the non-isothermal melting crystallization behavior (the test method is the same as above, FIG. 3 ). The thermal performance parameters of PLLA/PDLA blend modified materials with different nucleating agent dosages are shown in Table 2.

Table 2: Thermal performance parameters in non-isothermal melt crystallization of PLLA/PDLA blends with different amounts of nucleating agents

It can be seen from Table 2 and Figure 3 that as the amount of nucleating agent increases, the stereocomplex crystallization speed of the PLLA/PDLA blend system increases, and the content of stereocomplex crystals increases. When the amount of PPZn nucleating agent is ≥ 1wt%, stereocomposite crystallization.

Example 12, 13

The contents of PLLA and PDLA are different, and all contain 1wt% PPZn nucleating agent; PLLA, PDLA and nucleating agent are respectively weighed according to the composition mass ratio of Table 3 and dissolved in chloroform, and the concentration of the polymer solution is 50g/L. Stir Make it mix evenly, then cast it in a polytetrafluoroethylene petri dish, let the solvent evaporate completely at room temperature, and then dry it in a vacuum oven at 60°C for 6h. DSC is used to test the non-isothermal melting crystallization behavior (the test method is the same as above). The thermal performance parameters of PLLA/PDLA/PPZn blends with different PLLA and PDLA contents are shown in Table 3.

In order to further illustrate the nucleating effect of the nucleating agent on the non-equivalent PLLA/PDLA blend system, no nucleating agent was included in Comparative Example 12 and Comparative Example 13, and the mass ratio of PLLA and PDLA was the same as in Examples 12 and 13. , PLLA and PDLA were respectively weighed according to the composition mass ratio in Table 3 and then dissolved in chloroform. The concentration of the polymer solution was 50g/L. Stir to make it evenly mixed, then cast it in a polytetrafluoroethylene petri dish, and use it at room temperature. The solvent was completely evaporated, and then dried in a vacuum oven at 60°C for 6h. DSC is used to test the non-isothermal melting crystallization behavior (the test method is the same as above). The thermal performance parameters of PLLA/PDLA blends with different PLLA and PDLA contents are shown in Table 3.

Table 3 Thermal performance parameters of non-isothermal crystallization of PLLA/PDLA blends with different PLLA and PDLA contents

It can be seen from Table 3 that for PLLA/PDLA blend systems with unequal mass ratios of PLLA and PDLA, the addition of organometallic phosphonate nucleating agents can also increase the crystallization rate of the blend system and increase the content of stereocomplex crystals. In combination with Examples 1, 12, 13 and Comparative Examples 1, 12, 13, it can be found that when the mass percentage of PLLA/PDLA is between 50/50 and 70/30, after adding 1wt% PPZn nucleating agent, all can be completely Formation of three-dimensional complex crystals. When the mass percentage of PLLA/PDLA is 70/30, after adding 1wt% PPZn nucleating agent, three-dimensional composite crystals can be completely formed. It can be seen that this technology can reduce the content of PDLA in the blend system and reduce the production of high-resistance PLA materials. cost.

The isothermal melting crystallization kinetics of the blends of Comparative Example 1 and Examples 1, 9, and 10 at 140°C were analyzed by DSC (the test method is as above, Figure 4), and the kinetic and thermal performance parameters are shown in Table 4.

Table 4 Kinetic and thermal performance parameters of isothermal melt crystallization of PLLA/PDLA blends before and after modification at 140 °C

It can be seen from Table 4 and Figure 4 that after adding an organometallic phosphonate nucleating agent to the PLLA/PDLA blend, t0.5 is significantly shortened, and the content of stereocomplex crystals is significantly increased. In addition, the morphology of spherulites was observed by using POM (the method is the same as above), and it was found that after adding an organic phosphonate nucleating agent to the PLLA/PDLA blend, the size of spherulites decreased and the nucleation density increased significantly. When the amount of nucleating agent added is 1wt%, t _0.5 is reduced to 0.65min, which can effectively improve the processing efficiency and meet the requirements of actual molding processing, and also completely form a high-melting point stereocomposite crystal. WAXD test was carried out on its 140°C isothermal melting crystal sample (as shown in Figure 5), and it was found that after adding 1 wt% PPZn, only stereocomplex crystals were formed in the blend system.

The test results of dynamic mechanical properties found that the storage modulus of the modified material in Example 1 was 4.53MPa at 200°C, while the storage modulus of the unmodified material in Comparative Example 1 was 0.09MPa at 200°C. It shows that after adding the organometallic phosphonate nucleating agent, the heat resistance of the material is significantly improved.

Finally, it should be noted that what is listed above are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and many modifications are possible. All deformations that can be directly derived or associated by those skilled in the art from the content disclosed in the present invention should be considered as the protection scope of the present invention.

Claims (10)

1. can the preparation method of high-molecular-weighpolylactic polylactic acid stereoscopic compound material of rapid crystallization, comprise the use of organic metal phosphonic acid salt nucleator, it is characterized in that, concrete preparation process comprises: get poly(lactic acid) matrix, organo-metallic phosphonate nucleator adopts solution or melt blending, and can obtain can the high-molecular-weighpolylactic polylactic acid stereoscopic compound material of rapid crystallization;

Wherein, the quality of organo-metallic phosphonate nucleator accounts for 0.1% ~ 3% of total composition, and the quality of poly(lactic acid) matrix accounts for 99.9 ~ 97% of total composition, and the mass percent sum of each component is 100%; Described poly(lactic acid) matrix refers to Poly-L-lactic acid (PLLA) and dextrorotation poly(lactic acid) (PDLA), and in poly(lactic acid) matrix, the mass percent of Poly-L-lactic acid is 50% ~ 90%, and the mass percent of dextrorotation poly(lactic acid) is 10% ~ 50%;

Described organo-metallic phosphonate nucleator adopts any one material in phenide phosphonate, phenide phosphinates or phenylbenzene metal phosphinate hydrochlorate.

2. according to claim 1 can the preparation method of high-molecular-weighpolylactic polylactic acid stereoscopic compound material of rapid crystallization, it is characterized in that, when adopting solution blended process to prepare, concrete grammar is: get Poly-L-lactic acid, dextrorotation poly(lactic acid), organo-metallic phosphonate nucleator, be dissolved in easy volatile solvent, the concentration of polymers soln is 50g/L, after being uniformly mixed, polymers soln is watered and casts from tetrafluoroethylene culture dish, then easy volatile solvent is made to volatilize completely under room temperature, again tetrafluoroethylene culture dish is put into the dry 6h of vacuum drying oven of 60 DEG C, namely obtaining can the high-molecular-weighpolylactic polylactic acid stereoscopic compound material of rapid crystallization.

3. according to claim 2 can the preparation method of high-molecular-weighpolylactic polylactic acid stereoscopic compound material of rapid crystallization, it is characterized in that, described easy volatile solvent adopts methylene dichloride or chloroform.

4. according to claim 1 can the preparation method of high-molecular-weighpolylactic polylactic acid stereoscopic compound material of rapid crystallization, it is characterized in that, when adopting melt-blending process to prepare, concrete grammar is: get Poly-L-lactic acid, dextrorotation poly(lactic acid), organo-metallic phosphonate nucleator add in forcing machine, then mixing 3min at 230 DEG C, extrude pelletizing again, namely obtaining can the high-molecular-weighpolylactic polylactic acid stereoscopic compound material of rapid crystallization.

5. according to claim 4 can the preparation method of high-molecular-weighpolylactic polylactic acid stereoscopic compound material of rapid crystallization, it is characterized in that, when adopting melt-blending process to prepare, in forcing machine, also can add carbodiimide hydrolysis-resisting agent, Hinered phenols antioxidant.

6. according to claim 1 can the preparation method of high-molecular-weighpolylactic polylactic acid stereoscopic compound material of rapid crystallization, it is characterized in that, the phosphatic structural formula of described phenide is:

Wherein, M is divalent metal.

7. according to claim 1 can the preparation method of high-molecular-weighpolylactic polylactic acid stereoscopic compound material of rapid crystallization, it is characterized in that, the structural formula of described phenide phosphinates is:

Wherein, M is divalent metal.

8. according to claim 1 can the preparation method of high-molecular-weighpolylactic polylactic acid stereoscopic compound material of rapid crystallization, it is characterized in that, the structural formula of described phenylbenzene metal phosphinate hydrochlorate is:

Wherein, M is divalent metal.

9. according to claim 6 to 8 any one can the preparation method of high-molecular-weighpolylactic polylactic acid stereoscopic compound material of rapid crystallization, it is characterized in that, described M adopts at least one divalent metal in zinc, barium, calcium.

10. according to claim 1 can the preparation method of high-molecular-weighpolylactic polylactic acid stereoscopic compound material of rapid crystallization, it is characterized in that, the weight-average molecular weight of described Poly-L-lactic acid, dextrorotation poly(lactic acid) is all greater than 80kg/mol, and optical purity is greater than 95%; The particle diameter of organo-metallic phosphonate nucleator is between 10 ~ 30 microns.