CN115594961B - A kind of high-toughness heat-resistant polylactic acid composite material and its preparation method - Google Patents

Abstract

The invention discloses a high-toughness heat-resistant polylactic acid composite material and a preparation method thereof, belonging to the technical field of polylactic acid modification. The high-toughness heat-resistant polylactic acid composite material is based on polylactic acid as a matrix, montmorillonite grafted lactide as a filler, and polybutylene terephthalate succinate as a toughening agent. The prepared glycidyl methacrylate and butyl methacrylate co-graft polylactic acid as a compatibilizer, diphenyl dihydrazide sebacic acid as a nucleating agent, and is prepared by melt blending. The polylactic acid composite material prepared by the present invention has lower raw material cost, higher toughness and heat distortion temperature and complete biodegradability, is suitable for medical treatment, clothing, automobile, food packaging and other fields, and has significant economic value and social benefits.

Description

A kind of high-toughness heat-resistant polylactic acid composite material and its preparation method

technical field

The invention belongs to the technical field of polylactic acid modification, and in particular relates to a high-toughness heat-resistant polylactic acid composite material and a preparation method thereof.

Background technique

In recent years, with the gradual depletion of petroleum resources and various increasingly prominent environmental problems, biodegradable polymer materials have become an extremely important research direction in the field of polymer materials. Among the currently developed biodegradable polymer materials, polylactic acid is widely used in medical and health care, food packaging, etc. , automobiles, clothing and other fields. However, the rigidity of the molecular segment of polylactic acid is relatively large, and the movement ability of the segment is poor, resulting in poor toughness of polylactic acid. At the same time, the crystallization rate of PLA is slower and the degree of crystallinity is lower, resulting in a lower heat distortion temperature of PLA. These shortcomings greatly reduce the application value of polylactic acid.

Contents of the invention

The present invention aims at the problems of poor toughness and low thermal deformation temperature of polylactic acid at present, and provides a high-toughness heat-resistant polylactic acid composite material and a preparation method thereof, and the prepared polylactic acid composite material has lower raw material Low cost, large elongation at break, high heat distortion temperature and complete biodegradability, suitable for medical, clothing, automobile, food packaging and other fields, with significant economic value and social benefits.

To achieve the above object, the present invention adopts the following technical solutions:

A high-toughness heat-resistant polylactic acid composite material, which uses polylactic acid as a matrix, montmorillonite grafted lactide as a filler, and polybutylene terephthalate as a toughening agent. Glycidyl methacrylate and butyl methacrylate were co-grafted with polylactic acid as compatibilizer and diphenyl dihydrazide sebacic acid as nucleating agent, prepared by melt blending. Its concrete preparation steps are as follows:

(1) First add 30~50 g of polylactic acid into the mixing chamber of the torque rheometer, banbury at 170~190 ℃ for 1~3min, then add 2~8 g of glycidyl methacrylate, 4 ~12 g butyl methacrylate and 0.1~0.5 g initiator, continue banburying at 160~200 °C for 5~7 min, cool and pulverize to obtain glycidyl methacrylate and butyl methacrylate Grafted polylactic acid;

(2) Under nitrogen protection, add 30-50 g of montmorillonite to 200-500 mL of dimethyl sulfoxide, stir mechanically at room temperature for 20-40 min, then add 10-30 g of lactide, and heat up To 100~140 ℃, continue mechanical stirring for 30~60 min, then add 0.02~0.1 g catalyst, continue mechanical stirring for 8~12 h, filter, wash, dry, and grind to obtain montmorillonite grafted lactide;

(3) 15~35 g polylactic acid, 5~20 g montmorillonite grafted lactide, 7~20 g polybutylene terephthalate, 1~9 g glycidyl methacrylate Add polylactic acid co-grafted with butyl methacrylate and 0.05-0.25 g diphenyl dihydrazide sebacate into the mixing chamber of the torque rheometer in turn, and banbury at 160-200 °C for 5-10 min, after cooling and crushing, the high-toughness heat-resistant polylactic acid composite material was obtained.

Further, the initiator in step (1) is any one of azobisisobutyronitrile, dicumyl peroxide or benzoyl peroxide.

Further, the catalyst in step (2) is any one of p-dimethylaminopyridine, stannous octoate or tris(xylyl)phosphate.

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

(1) The present invention aims at the problem of poor compatibility between polybutylene terephthalate and polylactic acid, and utilizes melt grafting method to prepare glycidyl methacrylate and butyl methacrylate co-grafted polylactic acid, And use it as a compatibilizer to improve the compatibility of polybutylene terephthalate and polylactic acid.

(2) The present invention aims at the problem of poor compatibility between montmorillonite and polylactic acid. On the one hand, lactide that can react with terminal hydroxyl and carboxyl groups of polylactic acid is grafted on the surface of montmorillonite; The glycidyl methacrylate can react with the lactide on the surface of montmorillonite and the terminal hydroxyl and carboxyl groups of polylactic acid respectively, which improves the compatibility of montmorillonite and polylactic acid, and ensures that montmorillonite can be used in polylactic acid. can be dispersed evenly and stably.

(3) Because the activity of free radical reaction between butyl methacrylate and polylactic acid is greater than the activity of free radical reaction between glycidyl methacrylate and polylactic acid, and glycidyl methacrylate and butyl methacrylate co-react. The reaction rate of polymerization is greater than the reaction rate of self-polymerization of glycidyl methacrylate. Therefore, in the preparation of the compatibilizer of the present invention, butyl methacrylate will be preferentially grafted on the polylactic acid molecular chain, and then combined with methyl Copolymerization of glycidyl acrylate can increase the grafting rate of glycidyl methacrylate, and a compatibilizer with a high grafting rate can better improve the compatibility between the components.

(4) Sebacic acid diphenyl dihydrazide is a heterogeneous nucleating agent of polylactic acid, which can increase the nucleation rate and crystal nucleus density of polylactic acid, and achieve the purpose of increasing the crystallinity and heat distortion temperature of polylactic acid. At the same time, high concentration, uniform and stable dispersion of montmorillonite in polylactic acid can also increase the heat distortion temperature of polylactic acid.

(5) The polylactic acid, polybutylene terephthalate and montmorillonite used in the present invention are all fully biodegradable polymer materials or natural clays. Therefore, the high-toughness heat-resistant Polylactic acid composite materials are environmentally friendly and fully biodegradable polymer materials, which conform to the national environmental protection concept and meet the requirements of sustainable development.

(6) Polybutylene terephthalate can endow polylactic acid composites with excellent toughness, and high content of montmorillonite can reduce the raw material cost of polylactic acid composites, and its combination with diphenyl sebacate All hydrazides can increase the heat deflection temperature of the polylactic acid composite material. Therefore, the polylactic acid composite material prepared by the present invention has lower raw material cost, higher toughness and heat deflection temperature, and complete biodegradability. The elongation rate is 85.3~91.6%, the impact strength is 6.98~7.65 kJ/m ² , and the heat distortion temperature is 67.3~73.5 ℃. It is mainly used in the fields of medical treatment, clothing, automobiles, and food packaging, and has significant economic and social benefits.

Description of drawings

Fig. 1 is the infrared absorption spectrogram of glycidyl methacrylate and butyl methacrylate co-grafted polylactic acid prepared by embodiment 1;

Fig. 2 is the infrared absorption spectrogram of the montmorillonite grafted lactide prepared in Example 1.

Detailed ways

A high-toughness heat-resistant polylactic acid composite material, its specific preparation steps are as follows:

(1) First add 30~50 g of polylactic acid into the mixing chamber of the torque rheometer, banbury at 170~190 ℃ for 1~3min, then add 2~8 g of glycidyl methacrylate, 4 ~12 g butyl methacrylate and 0.1~0.5 g initiator, continue banburying at 160~200 °C for 5~7 min, cool and pulverize to obtain glycidyl methacrylate and butyl methacrylate Grafted polylactic acid;

(2) Under nitrogen protection, add 30-50 g of montmorillonite to 200-500 mL of dimethyl sulfoxide, stir mechanically at room temperature for 20-40 min, then add 10-30 g of lactide, and heat up To 100~140 ℃, continue mechanical stirring for 30~60 min, then add 0.02~0.1 g catalyst, continue mechanical stirring for 8~12 h, filter, wash, dry, and grind to obtain montmorillonite grafted lactide;

(3) 15~35 g polylactic acid, 5~20 g montmorillonite grafted lactide, 7~20 g polybutylene terephthalate, 1~9 g glycidyl methacrylate Add polylactic acid co-grafted with butyl methacrylate and 0.05-0.25 g diphenyl dihydrazide sebacate into the mixing chamber of the torque rheometer in turn, and banbury at 160-200 °C for 5-10 min, after cooling and crushing, the high-toughness heat-resistant polylactic acid composite material was obtained.

Wherein, the initiator in step (1) is any one of azobisisobutyronitrile, dicumyl peroxide or benzoyl peroxide.

The catalyst in step (2) is any one of p-dimethylaminopyridine, stannous octoate or tris(xylyl)phosphate.

In order to make the content of the present invention easier to understand, the technical solutions of the present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

Example 1

(1) First add 40 g of polylactic acid into the mixing chamber of the torque rheometer, and banbury at 180 °C for 2 min, then add 5 g of glycidyl methacrylate, 8 g of butyl methacrylate and 0.3 g of dicumyl peroxide, continued banburying at 180 °C for 6 min, cooled and pulverized to obtain glycidyl methacrylate and butyl methacrylate co-grafted polylactic acid;

(2) Under nitrogen protection, add 40 g of montmorillonite to 350 mL of dimethyl sulfoxide, stir mechanically at room temperature for 30 min, then add 20 g of lactide, raise the temperature to 120 °C, and continue mechanically stirring for 45 min min, then add 0.06 g stannous octoate, continue mechanical stirring for 10 h, filter, wash, dry, grind to obtain montmorillonite grafted lactide;

(3) 25 g polylactic acid, 12 g montmorillonite grafted lactide, 14 g polybutylene terephthalate, 5 g glycidyl methacrylate and butyl methacrylate were co-grafted Dendritic polylactic acid and 0.15 g diphenyl dihydrazide sebacate were sequentially added into the mixing chamber of the torque rheometer, and mixed at 180 °C for 7 min, cooled and pulverized to obtain a high-toughness heat-resistant polymer. Lactic acid composite.

Fig. 1 is the infrared absorption spectrogram of glycidyl methacrylate and butyl methacrylate co-grafted polylactic acid prepared in this example. It can be seen from the figure that compared with the infrared absorption spectrum of polylactic acid, the epoxy group at 910 cm ^-1 appears in the infrared absorption spectrum of glycidyl methacrylate and butyl methacrylate co-grafted polylactic acid group characteristic absorption peak, which indicates that glycidyl methacrylate has successfully grafted polylactic acid, and at the same time, in the infrared absorption spectrum of glycidyl methacrylate and butyl methacrylate co-grafted polylactic acid, it is located at 2997 cm ^-1 The intensity of the methylene absorption peak at 1749 cm -1 and the carbonyl absorption peak at 1749 cm ^-1 were significantly enhanced, which indicated that butyl methacrylate was successfully grafted to polylactic acid.

Figure 2 is the infrared absorption spectrum of the montmorillonite grafted lactide prepared in this example. It can be seen from the figure that compared with the infrared absorption spectrum of montmorillonite, the carbonyl characteristic absorption peak at 1749 cm ^-1 appears in the infrared absorption spectrum of montmorillonite grafted lactide, which indicates that montmorillonite Lactide was successfully grafted.

Example 2

(1) Firstly, 30 g of polylactic acid was added into the mixing chamber of the torque rheometer, and mixed at 170 °C for 3 min, and then 2 g of glycidyl methacrylate, 4 g of butyl methacrylate and 0.1 g of azobisisobutyronitrile, continued banburying at 160 °C for 7 minutes, cooled and pulverized to obtain glycidyl methacrylate and butyl methacrylate co-grafted polylactic acid;

(2) Under nitrogen protection, add 30 g of montmorillonite to 200 mL of dimethyl sulfoxide, stir mechanically at room temperature for 20 min, then add 10 g of lactide, raise the temperature to 100 °C, and continue mechanically stirring for 60 min min, then add 0.02 g dimethylaminopyridine, continue mechanical stirring for 12 h, filter, wash, dry and grind to obtain montmorillonite grafted lactide;

(3) 15 g of polylactic acid, 5 g of montmorillonite-grafted lactide, 7 g of polybutylene terephthalate, 1 g of glycidyl methacrylate and butyl methacrylate were co-grafted Dendritic polylactic acid and 0.05 g diphenyl dihydrazide sebacate were sequentially added into the mixing chamber of the torque rheometer, and mixed at 160 °C for 10 min, cooled and pulverized to obtain a high-toughness heat-resistant polymer. Lactic acid composite.

Example 3

(1) Firstly, 50 g of polylactic acid was added into the mixing chamber of the torque rheometer, and mixed at 190 °C for 1 min, and then 8 g of glycidyl methacrylate, 12 g of butyl methacrylate and 0.5 g of benzoyl peroxide, continued banburying at 200 °C for 5 min, cooled and pulverized to obtain glycidyl methacrylate and butyl methacrylate co-grafted polylactic acid;

(2) Under nitrogen protection, add 50 g of montmorillonite to 500 mL of dimethyl sulfoxide, stir mechanically at room temperature for 40 min, then add 30 g of lactide, raise the temperature to 140 °C, and continue mechanically stirring for 30 min min, then add 0.1 g tris(xylyl) phosphate, continue mechanical stirring for 8 h, filter, wash, dry and grind to obtain montmorillonite grafted lactide;

(3) 35 g polylactic acid, 20 g montmorillonite grafted lactide, 20 g polybutylene terephthalate, 9 g glycidyl methacrylate and butyl methacrylate were co-grafted Dendritic polylactic acid and 0.25 g diphenyl dihydrazide sebacate were sequentially added into the mixing chamber of the torque rheometer, and mixed at 200 °C for 5 min, cooled and pulverized to obtain a high-toughness heat-resistant polymer. Lactic acid composite.

Comparative example 1

(1) Under nitrogen protection, add 40 g of montmorillonite to 350 mL of dimethyl sulfoxide, stir mechanically at room temperature for 30 min, then add 20 g of lactide, raise the temperature to 120 °C, and continue mechanically stirring for 45 min min, then add 0.06 g stannous octoate, continue mechanical stirring for 10 h, filter, wash, dry, grind to obtain montmorillonite grafted lactide;

(2) Add 25 g polylactic acid, 12 g montmorillonite grafted lactide, 14 g polybutylene terephthalate and 0.15 g diphenyl dihydrazide sebacate to the torque In the mixing chamber of the rheometer, it was internally kneaded at 180 °C for 7 minutes, cooled and pulverized to obtain the finished product.

Comparative example 2

(1) First add 40 g of polylactic acid into the mixing chamber of the torque rheometer, and banbury at 180 °C for 2 min, then add 5 g of glycidyl methacrylate, 8 g of butyl methacrylate and 0.3 g of dicumyl peroxide, continued banburying at 180 °C for 6 min, cooled and pulverized to obtain glycidyl methacrylate and butyl methacrylate co-grafted polylactic acid;

(2) 25 g of polylactic acid, 12 g of montmorillonite, 14 g of polybutylene terephthalate, 5 g of glycidyl methacrylate and butyl methacrylate were co-grafted with polylactic acid and 0.15 g of diphenyl dihydrazide sebacic acid was sequentially added to the mixing chamber of the torque rheometer, and banburyed at 180°C for 7 minutes, cooled and pulverized to obtain the finished product.

Comparative example 3

(1) First add 40 g of polylactic acid into the mixing chamber of the torque rheometer, and banbury at 180 °C for 2 min, then add 5 g of glycidyl methacrylate, 8 g of butyl methacrylate and 0.3 g of dicumyl peroxide, continued banburying at 180 °C for 6 min, cooled and pulverized to obtain glycidyl methacrylate and butyl methacrylate co-grafted polylactic acid;

(2) Under nitrogen protection, add 40 g of montmorillonite to 350 mL of dimethyl sulfoxide, stir mechanically at room temperature for 30 min, then add 20 g of lactide, raise the temperature to 120 °C, and continue mechanically stirring for 45 min min, then add 0.06 g stannous octoate, continue mechanical stirring for 10 h, filter, wash, dry, grind to obtain montmorillonite grafted lactide;

(3) 25 g polylactic acid, 12 g montmorillonite grafted lactide, 14 g polybutylene terephthalate, 5 g glycidyl methacrylate and butyl methacrylate were co-grafted Branched polylactic acid was sequentially added into the mixing chamber of the torque rheometer, and banburyed at 180 ℃ for 7 minutes, cooled and pulverized to obtain the finished product.

Comparative example 4

(1) First add 40 g of polylactic acid into the mixing chamber of the torque rheometer, and banbury at 180 °C for 2 min, then add 5 g of glycidyl methacrylate, 8 g of maleic anhydride and 0.3 g of Dicumyl peroxide, continue banburying at 180 °C for 6 minutes, cool and pulverize to obtain glycidyl methacrylate and maleic anhydride co-grafted polylactic acid;

(2) Under nitrogen protection, add 40 g of montmorillonite to 350 mL of dimethyl sulfoxide, stir mechanically at room temperature for 30 min, then add 20 g of lactide, raise the temperature to 120 °C, and continue mechanically stirring for 45 min min, then add 0.06 g stannous octoate, continue mechanical stirring for 10 h, filter, wash, dry, grind to obtain montmorillonite grafted lactide;

(3) 25 g of polylactic acid, 12 g of montmorillonite grafted lactide, 14 g of polybutylene terephthalate, 5 g of glycidyl methacrylate and maleic anhydride were co-grafted into poly Lactic acid and 0.15 g diphenyl dihydrazide sebacic acid were sequentially added into the mixing chamber of the torque rheometer, and mixed at 180 °C for 7 min, cooled and pulverized to obtain the finished product.

Comparative example 5

(1) First add 40 g of polylactic acid into the mixing chamber of the torque rheometer, banbury at 180 °C for 2 min, then add 5 g of glycidyl methacrylate and 0.3 g of dicumyl peroxide in sequence , continued banburying at 180 °C for 6 min, cooled and pulverized to obtain glycidyl methacrylate grafted polylactic acid;

(2) Under nitrogen protection, add 40 g of montmorillonite to 350 mL of dimethyl sulfoxide, stir mechanically at room temperature for 30 min, then add 20 g of lactide, raise the temperature to 120 °C, and continue mechanically stirring for 45 min min, then add 0.06 g stannous octoate, continue mechanical stirring for 10 h, filter, wash, dry, grind to obtain montmorillonite grafted lactide;

(3) 25 g polylactic acid, 12 g montmorillonite grafted lactide, 14 g polybutylene terephthalate, 5 g glycidyl methacrylate grafted polylactic acid and 0.15 g capric acid The diacid diphenyl dihydrazide was sequentially added into the mixing chamber of the torque rheometer, and banburyed at 180 ℃ for 7 minutes, cooled and pulverized to obtain the finished product.

Comparative example 6

(1) First add 40 g of polylactic acid into the mixing chamber of the torque rheometer, and banbury at 180 °C for 2 min, then add 8 g of butyl methacrylate and 0.3 g of dicumyl peroxide in sequence, Continue banburying at 180°C for 6 minutes, cool and pulverize to obtain butyl methacrylate grafted polylactic acid;

(2) Under nitrogen protection, add 40 g of montmorillonite to 350 mL of dimethyl sulfoxide, stir mechanically at room temperature for 30 min, then add 20 g of lactide, raise the temperature to 120 °C, and continue mechanically stirring for 45 min min, then add 0.06 g stannous octoate, continue mechanical stirring for 10 h, filter, wash, dry, grind to obtain montmorillonite grafted lactide;

(3) 25 g polylactic acid, 12 g montmorillonite grafted lactide, 14 g polybutylene terephthalate, 5 g butyl methacrylate grafted polylactic acid and 0.15 g decane Acid diphenyl dihydrazide was sequentially added into the mixing chamber of the torque rheometer, and banburyed at 180 °C for 7 minutes, cooled and pulverized to obtain the finished product.

The products prepared in Examples and Comparative Examples were tested for tensile strength and elongation at break according to GB/T 1040-2006, for impact strength according to GB/T 1043-2008, and for thermal deformation according to GB/T 1634-2019 Temperature test, the test results are shown in Table 1.

Table 1 Performance test results

From the test results, it can be seen that with montmorillonite grafted lactide as filler and polybutylene terephthalate as toughener, glycidyl methacrylate and formazan prepared by melt grafting method Butyl acrylate co-grafted polylactic acid as a compatibilizer, diphenyl dihydrazide sebacic acid as a nucleating agent, and a polylactic acid composite material with high toughness and heat distortion temperature can be prepared by melt blending. Moreover, the raw material cost is low, and the biodegradability is completely biodegradable, so it has a good application prospect.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (4)

1. A preparation method for a high-toughness heat-resistant polylactic acid composite material, characterized in that: the high-toughness heat-resistant polylactic acid composite material is based on polylactic acid, and montmorillonite grafted lactide is a filler, poly Butylene terephthalate succinate is used as toughening agent, glycidyl methacrylate and butyl methacrylate co-grafted polylactic acid prepared by melt grafting method are used as compatibilizer, diphenyl sebacate Dihydrazide is a nucleating agent prepared by melt blending; Its concrete preparation steps are as follows: (1) First banbury 30~50 g polylactic acid at 170~190 ℃ for 1~3 min, then add 2~8 g glycidyl methacrylate, 4~12 g butyl methacrylate and 0.1~0.5 g initiator, continue banburying at 160-200°C for 5-7 minutes, cool and pulverize to obtain glycidyl methacrylate and butyl methacrylate co-grafted polylactic acid; (2) Under nitrogen protection, add 30-50 g of montmorillonite to 200-500 mL of dimethyl sulfoxide, stir mechanically at room temperature for 20-40 min, then add 10-30 g of lactide, and heat up To 100~140 ℃, continue mechanical stirring for 30~60 min, then add 0.02~0.1 g catalyst, continue mechanical stirring for 8~12 h, filter, wash, dry, and grind to obtain montmorillonite grafted lactide; (3) Add 15~35 g polylactic acid, 5~20 g montmorillonite grafted lactide, 7~20 g polybutylene terephthalate, 1~9 g glycidyl methacrylate in sequence ester and butyl methacrylate co-grafted polylactic acid and 0.05~0.25 g diphenyl dihydrazide sebacate, and banburying at 160~200 ℃ for 5~10 min, cooling and pulverizing to obtain the high Tough heat-resistant polylactic acid composite. 2. The preparation method of high-toughness heat-resistant polylactic acid composite material according to claim 1, characterized in that: the initiator in step (1) is azobisisobutyronitrile, dicumyl peroxide or peroxide Any of the benzoyls. 3. The method for preparing a high-toughness heat-resistant polylactic acid composite material according to claim 1, wherein the catalyst in step (2) is p-dimethylaminopyridine, stannous octoate or tris(xylyl)phosphoric acid any of the esters. 4. A high-toughness heat-resistant polylactic acid composite material prepared by the method according to claim 1.