Oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material and preparation method thereof

Abstract

The invention belongs to the technical field of high polymer materials, particularly discloses an oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material, and also discloses a preparation method of the oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material. The oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material provided by the invention is prepared from the following raw materials: PLA, PBAT, thermoplastic starch TPS and a chain extender. A plasticizer adopted for thermoplastic starch TPS plasticizing treatment simultaneously contains three polar groups including hydroxyl, acylamino and sulfonic acid groups, the obtained thermoplastic starch TPS is high in plasticizing efficiency, and the processing performance of the composite material is remarkably improved. The two ends of the adopted polyester chain extender contain oxazoline groups, the PLA / PBAT / TPS composite material is subjected to chain extension, the interfacial compatibility is enhanced, and the PLA / PBAT / TPS composite material with excellent mechanical properties is prepared.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and specifically relates to an oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material, and also relates to a preparation method thereof. Background Art

[0002] With the progress of society, plastic has become one of the most widely used materials in modern life. However, the large-scale use of plastics will cause environmental pollution, and biodegradable plastics have become a research hotspot to solve this problem. Polylactic acid (PLA) is a new type of biodegradable material with the characteristics of high tensile strength, high hardness, and excellent processing performance. It has become one of the important biodegradable materials. Polybutylene adipate-terephthalate (PBAT) is a fully biodegradable aromatic polyester that has both the flexibility of the PBA segment and the heat resistance and impact resistance of the PBT segment. Adding PBAT to PLA for blending modification can improve the brittleness of PLA itself. At the same time, adding starch can reduce costs and ensure the biodegradability of the composite material. However, the strong hydrogen bonding and high crystallization of starch make the thermoplasticity of natural starch poor and difficult to process, resulting in the inability of PBAT and PLA composite materials with starch added to perform normal melt extrusion. At present, there is a method of using plasticizers to plasticize starch to make thermoplastic starch resin (TPS) and then adding it into PBAT and PLA, but there are still problems such as poor starch plasticization efficiency and poor processing performance.

[0003] In addition, due to the poor compatibility between PBAT, PLA and TPS, in order to obtain a composite material with excellent performance, a chain extender needs to be added to improve the compatibility between the three. However, the existing chain extenders are still insufficient in changing the interfacial compatibility of the three, and further improvement is needed.

[0004] Based on the above problems, the present invention aims to provide a new PLA / PBAT / TPS composite material with good mechanical properties. Summary of the invention

[0005] The present invention aims to provide an oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material, and also provides a preparation method thereof.

[0006] To achieve the above objectives, the present invention adopts the following technical solutions.

[0007] In a first aspect, the present invention provides an oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material, the raw materials for its preparation include: PLA, PBAT, thermoplastic starch TPS, and a chain extender;

[0008] The thermoplastic starch TPS is starch treated with a plasticizer, wherein the plasticizer comprises a chemical structure of The compounds shown;

[0009] The chain extender is a polyester chain extender containing an oxazoline end group, including chain extenders shown in Formula I and Formula II;

[0010]

[0011] In formula I, the value range of m is 2000-4000.

[0012] In formula II, the value range of n is 2000-4000.

[0013] As an embodiment of the present invention, in the raw material for preparing the composite material, the molecular weight range of the PLA is 25000-35000.

[0014] As an embodiment of the present invention, in the raw material for preparing the composite material, the molecular weight range of the PBAT is 50,000-70,000.

[0015] As an embodiment of the present invention, in the raw materials for preparing the composite material, the mass ratio of the PBAT to the PLA is (20-40): (60-80).

[0016] As an embodiment of the present invention, in the raw materials for preparing the composite material, the mass ratio of the thermoplastic starch TPS to the PLA is (15-30): (60-80).

[0017] As an embodiment of the present invention, in the raw materials for preparing the composite material, the mass ratio of the chain extender to the PLA is (0.5-2): (60-80).

[0018] As an embodiment of the present invention, the chain extender is a mixture of the chain extender of formula I and the chain extender of formula II. Preferably, in the chain extender, the chain extender of formula I and the chain extender of formula II are mixed in a mass ratio of (1-2): (1-2).

[0019] As an embodiment of the present invention, the thermoplastic starch TPS is obtained by mixing starch with the plasticizer, wherein the starch and the plasticizer are mixed in a mass ratio of 100:(5-30).

[0020] As an embodiment of the present invention, the mixing process comprises: mixing starch with the plasticizer, extruding using a twin-screw extruder, setting the temperature from the first zone to the head of the twin-screw extruder to 90-130°C, then cooling to 20-40°C, and drying to obtain the thermoplastic starch TPS.

[0021] As an embodiment of the present invention, the plasticizer is prepared using ethyl formate and 4-hydroxybenzenesulfonamide as raw materials, comprising the steps of: mixing the ethyl formate and the 4-hydroxybenzenesulfonamide in a molar ratio of (1-1.2): (1-1.2), using ethanol as a solvent, stirring and reacting at 40-60° C., and then evaporating the ethanol to obtain the plasticizer.

[0022] As an embodiment of the present invention, the chain extender shown in formula I is prepared by reacting PBT with 2,2'-bis(2-oxazoline), comprising the steps of mixing PBT with 2,2'-bis(2-oxazoline) and reacting at 190-200° C. to obtain the chain extender shown in formula I.

[0023] As an embodiment of the present invention, the chain extender shown in formula II is prepared by reacting PBA with 2,2'-bis(2-oxazoline), comprising the steps of mixing PBA with 2,2'-bis(2-oxazoline) and reacting at 190-200° C. to obtain the chain extender shown in formula II.

[0024] In a second aspect, the present invention provides a method for preparing the oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material of the present invention, comprising the steps of: mixing PLA, PBAT, thermoplastic starch TPS, and a chain extender, and then feeding them into a twin-screw extruder, wherein the temperature of the twin-screw extruder is controlled to be 150-190°C, the screw speed is controlled to be 100-300rpm, and extrusion and granulation are performed by the twin-screw extruder to obtain the oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material.

[0025] As an embodiment of the present invention, the PLA, PBAT, thermoplastic starch TPS, and chain extender are mixed in an environment of 60-100° C. for 10-30 minutes.

[0026] In a third aspect, the present invention provides an application of the oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material. The PLA / PBAT / TPS composite material provided by the present invention has excellent mechanical properties and can be used in injection molding products such as food containers and medical supplies, and blow molding products such as cling film, ground film, and various packaging films.

[0027] The oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material provided by the present invention is a novel polymer biodegradable material. The plasticizer used in the preparation of the raw material thermoplastic starch TPS plasticization treatment contains three polar groups of hydroxyl, amide and sulfonic acid at the same time, and the starch is plasticized and modified, which can efficiently destroy the crystal structure of the starch, make the starch processable, realize the thermoplasticization of the starch, and the obtained thermoplastic starch TPS plasticization efficiency is high, which significantly improves the processing performance of the composite material. The polyester chain extender used contains oxazoline groups at both ends, and the oxazoline groups have the characteristics of strong activity, fast reaction speed, and no small molecule generation in the reaction. It can react with the carboxylic acid group to form an amide group, increase the relative molecular weight of the polymer, improve thermal stability and improve compatibility, etc. The polyester chain extender provided by the present invention is used in PLA, PBAT, and TPS composite materials, and the PLA / PBAT / TPS composite material is chain extended, thereby enhancing the interface compatibility between the three, and preparing a PLA / PBAT / TPS composite material with excellent mechanical properties. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described in detail below. It should be understood by those skilled in the art that the specific implementation is only to help understand the present invention and should not be regarded as a specific limitation of the present invention.

[0029] It should be noted that, unless otherwise specified, the technical means used in the following examples are conventional means well known to those skilled in the art.

[0030] In the following examples and comparative examples, the plasticizer preparation process used is:

[0031] Ethyl formate and 4-hydroxybenzenesulfonamide were mixed in a molar ratio of 1:1, ethanol was used as a solvent, and the mixture was stirred at 50°C for 2 hours. The reaction formula is as follows. The ethanol was then distilled off under reduced pressure to obtain a plasticizer.

[0032]

[0033] Preparation of thermoplastic starch TPS: Starch and plasticizer are mixed, wherein the starch and plasticizer are mixed in a mass ratio of 100:(5-30). Specifically, the starch and plasticizer can be mixed in a mass ratio of 100:5, 100:10, 100:15, 100:20, 100:25, 100:30 or any other ratio within the range of 100:(5-30).

[0034] The starch and plasticizer mixing process includes: mixing the starch and the plasticizer in a high-speed mixer, then extruding with a twin-screw extruder, setting the temperature from the first zone of the twin-screw extruder to the die head to 90-130° C., then cooling to 20-40° C., and drying to obtain thermoplastic starch TPS.

[0035] In the raw materials for preparing the composite material, the mass ratio of PBAT to PLA is (20-40): (60-80). Specifically, the mass ratio of PBAT to PLA can be 20:60, 20:70, 20:80, 25:60, 25:70, 25:80, 30:60, 30:70, 30:80, 40:60, 40:70, 40:80 or any other ratio within the range of (20-40): (60-80).

[0036] In the raw materials for preparing the composite material, the mass ratio of thermoplastic starch TPS and PLA is (15-30):(60-80). Specifically, the mass ratio of TPS to PLA can be 15:60, 15:70, 15:80, 20:60, 20:70, 20:80, 25:60, 25:70, 25:80, 30:60, 30:70, 30:80 or any other ratio within the range of (15-30):(60-80).

[0037] In the raw materials for preparing the composite material, the mass ratio of the chain extender to PLA is (0.5-2):(60-80). Specifically, the mass ratio of the chain extender to PLA can be 0.5:60, 0.5:70, 0.5:80, 1.0:60, 1.0:70, 1.0:80, 1.5:60, 1.5:70, 1.5:80, 2.0:60, 2.0:70, 2.0:80 or any other ratio within the range of (0.5-2):(60-80).

[0038] In the raw materials for preparing the composite material, the chain extender used is a mixture of the chain extender shown in Formula I and the chain extender shown in Formula II, and the chain extender shown in Formula I and the chain extender shown in Formula II are mixed in a mass ratio of (1-2): (1-2). Specifically, in the chain extender, the chain extender shown in Formula I and the chain extender shown in Formula II can be mixed in a mass ratio of 1:2, 1:1, 2:1 or any other ratio within the range of (1-2): (1-2).

[0039] Unless otherwise specified, other raw materials are commercially available conventional products and can be purchased.

[0040] The following is a detailed explanation through specific examples.

[0041] Example 1

[0042] The present embodiment provides an oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material, the raw materials for preparation are: PLA (molecular weight 30,000), PBAT (molecular weight 60,000), thermoplastic starch TPS, and chain extender; the mass ratio of PLA, PBAT, thermoplastic starch TPS, and chain extender is 80:20:30:1.0.

[0043] The preparation method of thermoplastic starch TPS is as follows: starch and the plasticizer prepared above are uniformly mixed in a mass ratio of 100:20 using a high-speed mixer, and then extruded using a twin-screw extruder, the temperature from the first zone to the head of the twin-screw extruder is set to 130°C, and then cooled to room temperature (about 25°C), and dried to obtain thermoplastic starch TPS.

[0044] The chain extender includes the chain extenders shown in Formula I and Formula II, and the chain extenders shown in Formula I and Formula II are mixed in a mass ratio of 1:1;

[0045]

[0046] The preparation method of the chain extender shown in formula I is: terephthalic acid and butanediol are added in a molar ratio of 2:1, tetrabutyl titanate catalyst is added with a mass fraction of 5‰ of the mass of butanediol, and the reaction is carried out at 170°C for 6h to prepare PBT with carboxyl groups at both ends, wherein the value of m is 2500; the reaction formula is:

[0047]

[0048] PBT and 2,2'-bis(2-oxazoline) were added in a molar ratio of 1:2.2, and reacted at 190° C. for 2 hours to obtain a polyester chain extender containing an oxazoline end group as shown in Formula I.

[0049] The preparation method of the chain extender shown in formula II is: adipic acid and butanediol are added in a molar ratio of 2:1, tetrabutyl titanate catalyst is added with a mass fraction of 5‰ of the mass of butanediol, and the reaction is carried out at 170°C for 6h to prepare PBA with carboxyl groups at both ends, wherein the value of n is 2500; the reaction formula is:

[0050]

[0051] PBA and 2,2'-bis(2-oxazoline) were added in a molar ratio of 1:2.2, and reacted at 190° C. for 2 hours to obtain a polyester chain extender containing an oxazoline end group as shown in Formula II.

[0052] The oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material provided in this embodiment is prepared by:

[0053] PLA, PBAT, thermoplastic starch TPS and chain extender were mixed in a high-speed mixer at 60°C for 15 minutes in a mass ratio of 80:20:30:1.0, and then sent to a twin-screw extruder. The temperature of the twin-screw extruder was controlled at 180°C, and the screw speed was controlled at 150rpm. The extruder was extruded and granulated to obtain an oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material.

[0054] Example 2

[0055] The present embodiment provides an oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material, the raw materials for preparation are: PLA (molecular weight 30,000), PBAT (molecular weight 60,000), thermoplastic starch TPS, and chain extender; the mass ratio of PLA, PBAT, thermoplastic starch TPS, and chain extender is 80:20:30:1.5.

[0056] The preparation method of thermoplastic starch TPS is as follows: starch and the plasticizer prepared above are uniformly mixed in a mass ratio of 100:25 using a high-speed mixer, and then extruded using a twin-screw extruder, the temperature from the first zone to the head of the twin-screw extruder is set to 110°C, and then cooled to room temperature (about 25°C), and dried to obtain thermoplastic starch TPS.

[0057] The chain extender includes the chain extenders shown in Formula I and Formula II, and the chain extenders shown in Formula I and Formula II are mixed in a mass ratio of 1:1;

[0058]

[0059] The preparation method of the chain extender shown in formula I is as follows: terephthalic acid and butanediol are added in a molar ratio of 2:1, tetrabutyl titanate catalyst is added with a mass fraction of 5‰ of the mass of butanediol, and the reaction is carried out at 180°C for 6 hours to prepare PBT with carboxyl groups at both ends. The reaction formula is the same as that in Example 1, wherein the value of m is 3500;

[0060] PBT and 2,2'-bis(2-oxazoline) were added in a molar ratio of 1:2.2, and reacted at 190° C. for 2 hours to obtain a polyester chain extender containing an oxazoline end group as shown in Formula I.

[0061] The preparation method of the chain extender shown in formula II is as follows: adipic acid and butanediol are added in a molar ratio of 2:1, tetrabutyl titanate catalyst is added with a mass fraction of 5‰ of the mass of butanediol, and the reaction is carried out at 180°C for 6h to prepare PBA with carboxyl groups at both ends. The reaction formula is the same as that in Example 1, wherein the value of n is 3500;

[0062] PBA and 2,2'-bis(2-oxazoline) were added in a molar ratio of 1:2.2, and reacted at 190° C. for 2 hours to obtain a polyester chain extender containing an oxazoline end group as shown in Formula II.

[0063] The oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material provided in this embodiment is prepared by:

[0064] PLA, PBAT, thermoplastic starch TPS and chain extender were mixed in a high-speed mixer at 80°C for 20 minutes in a mass ratio of 80:20:30:1.5, and then sent to a twin-screw extruder. The temperature of the twin-screw extruder was controlled at 180°C, and the screw speed was controlled at 200 rpm. The mixture was extruded and granulated by the twin-screw extruder to obtain an oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material.

[0065] Example 3

[0066] The present embodiment provides an oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material, the raw materials for preparation are: PLA (molecular weight 30,000), PBAT (molecular weight 60,000), thermoplastic starch TPS, and chain extender; the mass ratio of PLA, PBAT, thermoplastic starch TPS, and chain extender is 80:20:30:2.0.

[0067] The preparation method of thermoplastic starch TPS is as follows: starch and the plasticizer prepared above are uniformly mixed in a mass ratio of 100:30 using a high-speed mixer, and then extruded using a twin-screw extruder, the temperature from the first zone to the head of the twin-screw extruder is set to 110°C, and then cooled to room temperature (about 25°C), and dried to obtain thermoplastic starch TPS.

[0068] The chain extender includes the chain extenders shown in Formula I and Formula II, and the chain extenders shown in Formula I and Formula II are mixed in a mass ratio of 1:1;

[0069]

[0070] The preparation method of the chain extender shown in formula I is as follows: terephthalic acid and butanediol are added in a molar ratio of 2:1, tetrabutyl titanate catalyst is added with a mass fraction of 5‰ of the mass of butanediol, and the reaction is carried out at 190°C for 6h to prepare PBT with carboxyl groups at both ends. The reaction formula is the same as that in Example 1, wherein the value of m is 4000;

[0071] PBT and 2,2'-bis(2-oxazoline) were added in a molar ratio of 1:2.2, and reacted at 190° C. for 2 hours to obtain a polyester chain extender containing an oxazoline end group as shown in Formula I.

[0072] The preparation method of the chain extender shown in formula II is as follows: adipic acid and butanediol are added in a molar ratio of 2:1, tetrabutyl titanate catalyst is added with a mass fraction of 5‰ of the mass of butanediol, and the reaction is carried out at 190°C for 6h to prepare PBA with carboxyl groups at both ends. The reaction formula is the same as that in Example 1, wherein the value of n is 4000;

[0073] PBA and 2,2'-bis(2-oxazoline) were added in a molar ratio of 1:2.2, and reacted at 190° C. for 2 hours to obtain a polyester chain extender containing an oxazoline end group as shown in Formula II.

[0074] The oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material provided in this embodiment is prepared by:

[0075] PLA, PBAT, thermoplastic starch TPS and chain extender were mixed in a high-speed mixer at 80°C for 20 minutes in a mass ratio of 80:20:30:2.0, and then sent to a twin-screw extruder. The temperature of the twin-screw extruder was controlled at 190°C, and the screw speed was controlled at 200 rpm. The mixture was extruded and granulated by the twin-screw extruder to obtain an oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material.

[0076] Example 4

[0077] The present embodiment provides an oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material, the raw materials for preparation are: PLA (molecular weight 30,000), PBAT (molecular weight 60,000), thermoplastic starch TPS, and chain extender; the mass ratio of PLA, PBAT, thermoplastic starch TPS, and chain extender is 80:20:20:1.5.

[0078] The preparation method of thermoplastic starch TPS is as follows: starch and the plasticizer prepared above are uniformly mixed in a mass ratio of 100:25 using a high-speed mixer, and then extruded using a twin-screw extruder, the temperature from the first zone to the head of the twin-screw extruder is set to 110°C, and then cooled to room temperature (about 25°C), and dried to obtain thermoplastic starch TPS.

[0079] The chain extender includes the chain extenders shown in Formula I and Formula II, and the chain extenders shown in Formula I and Formula II are mixed in a mass ratio of 1:1;

[0080]

[0081]

[0082] The preparation method of the chain extender shown in formula I is as follows: terephthalic acid and butanediol are added in a molar ratio of 2:1, tetrabutyl titanate catalyst is added with a mass fraction of 5‰ of the mass of butanediol, and the reaction is carried out at 180°C for 6 hours to prepare PBT with carboxyl groups at both ends. The reaction formula is the same as that in Example 1, wherein the value of m is 3500;

[0083] PBT and 2,2'-bis(2-oxazoline) were added in a molar ratio of 1:2.2, and reacted at 190° C. for 2 hours to obtain a polyester chain extender containing an oxazoline end group as shown in Formula I.

[0084] The preparation method of the chain extender shown in formula II is as follows: adipic acid and butanediol are added in a molar ratio of 2:1, tetrabutyl titanate catalyst is added with a mass fraction of 5‰ of the mass of butanediol, and the reaction is carried out at 180°C for 6h to prepare PBA with carboxyl groups at both ends. The reaction formula is the same as that in Example 1, wherein the value of n is 3500;

[0085] PBA and 2,2'-bis(2-oxazoline) were added in a molar ratio of 1:2.2, and reacted at 190° C. for 2 hours to obtain a polyester chain extender containing an oxazoline end group as shown in Formula II.

[0086] The oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material provided in this embodiment is prepared by:

[0087] PLA, PBAT, thermoplastic starch TPS and chain extender were mixed in a high-speed mixer at 80°C for 20 minutes in a mass ratio of 80:20:20:1.5, and then sent to a twin-screw extruder. The temperature of the twin-screw extruder was controlled at 180°C, and the screw speed was controlled at 200 rpm. The mixture was extruded and granulated by the twin-screw extruder to obtain an oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material.

[0088] Comparative Example 1

[0089] This comparative example provides an oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material, and the raw materials for preparation are: PLA (molecular weight 30,000), PBAT (molecular weight 60,000), and thermoplastic starch TPS; the mass ratio of PLA, PBAT, and thermoplastic starch TPS is 80:20:30.

[0090] The preparation method of thermoplastic starch TPS is as follows: starch and the plasticizer prepared above are uniformly mixed in a mass ratio of 100:30 using a high-speed mixer, and then extruded using a twin-screw extruder, the temperature from the first zone to the head of the twin-screw extruder is set to 110°C, and then cooled to room temperature (about 25°C), and dried to obtain thermoplastic starch TPS.

[0091] The oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material provided in this comparative example is prepared by:

[0092] PLA, PBAT and thermoplastic starch TPS were mixed in a high-speed mixer at 80°C for 20 minutes in a mass ratio of 80:20:30, and then sent to a twin-screw extruder. The temperature of the twin-screw extruder was controlled at 190°C and the screw speed was controlled at 200rpm. The PLA / PBAT / TPS composite material was obtained by extrusion and granulation.

[0093] Comparative Example 2

[0094] This comparative example provides an oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material, the raw materials for preparation are: PLA (molecular weight 30,000), PBAT (molecular weight 60,000), thermoplastic starch TPS, and chain extender; the mass ratio of PLA, PBAT, thermoplastic starch TPS, and chain extender is 80:20:30:1.5.

[0095] The preparation method of thermoplastic starch TPS is as follows: starch and the plasticizer prepared above are uniformly mixed in a mass ratio of 100:25 using a high-speed mixer, and then extruded using a twin-screw extruder, the temperature from the first zone to the head of the twin-screw extruder is set to 110°C, and then cooled to room temperature (about 25°C), and dried to obtain thermoplastic starch TPS.

[0096] The chain extender is a chain extender shown in Formula I:

[0097]

[0098] The preparation method of the chain extender shown in formula I is as follows: terephthalic acid and butanediol are added in a molar ratio of 2:1, tetrabutyl titanate catalyst is added with a mass fraction of 5‰ of the mass of butanediol, and the reaction is carried out at 180°C for 6 hours to prepare PBT with carboxyl groups at both ends. The reaction formula is the same as that in Example 1, wherein the value of m is 3500;

[0099] PBT and 2,2'-bis(2-oxazoline) were added in a molar ratio of 1:2.2, and reacted at 190° C. for 2 hours to obtain a polyester chain extender containing an oxazoline end group as shown in Formula I.

[0100] The oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material provided in this comparative example is prepared by:

[0101] PLA, PBAT, thermoplastic starch TPS and chain extender were mixed in a high-speed mixer at 80°C for 20 minutes in a mass ratio of 80:20:30:1.5, and then sent to a twin-screw extruder. The temperature of the twin-screw extruder was controlled at 180°C, and the screw speed was controlled at 200 rpm. The mixture was extruded and granulated by the twin-screw extruder to obtain an oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material.

[0102] Comparative Example 3

[0103] This comparative example provides an oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material, the raw materials for preparation are: PLA (molecular weight 30,000), PBAT (molecular weight 60,000), thermoplastic starch TPS, and chain extender; the mass ratio of PLA, PBAT, thermoplastic starch TPS, and chain extender is 80:20:30:1.5.

[0104] The preparation method of thermoplastic starch TPS is as follows: starch and the plasticizer prepared above are uniformly mixed in a mass ratio of 100:25 using a high-speed mixer, and then extruded using a twin-screw extruder, the temperature from the first zone to the head of the twin-screw extruder is set to 110°C, and then cooled to room temperature (about 25°C), and dried to obtain thermoplastic starch TPS.

[0105] The chain extender is a chain extender represented by formula II;

[0106]

[0107] The preparation method of the chain extender shown in formula II is as follows: adipic acid and butanediol are added in a molar ratio of 2:1, tetrabutyl titanate catalyst is added with a mass fraction of 5‰ of the mass of butanediol, and the reaction is carried out at 180°C for 6h to prepare PBA with carboxyl groups at both ends. The reaction formula is the same as that in Example 1, wherein the value of n is 3500;

[0108] PBA and 2,2'-bis(2-oxazoline) were added in a molar ratio of 1:2.2, and reacted at 190° C. for 2 hours to obtain a polyester chain extender containing an oxazoline end group as shown in Formula II.

[0109] The oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material provided in this comparative example is prepared by:

[0110] PLA, PBAT, thermoplastic starch TPS and chain extender were mixed in a high-speed mixer at 80°C for 20 minutes in a mass ratio of 80:20:30:1.5, and then sent to a twin-screw extruder. The temperature of the twin-screw extruder was controlled at 180°C, and the screw speed was controlled at 200 rpm. The mixture was extruded and granulated by the twin-screw extruder to obtain an oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material.

[0111] Comparative Example 4

[0112] This comparative example provides an oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material, the raw materials for preparation are: PLA (molecular weight 30,000), PBAT (molecular weight 60,000), thermoplastic starch TPS, and chain extender; the mass ratio of PLA, PBAT, thermoplastic starch TPS, and chain extender is 80:20:30:4.

[0113] The preparation method of thermoplastic starch TPS is as follows: starch and the plasticizer prepared above are uniformly mixed in a mass ratio of 100:25 using a high-speed mixer, and then extruded using a twin-screw extruder, the temperature from the first zone to the head of the twin-screw extruder is set to 110°C, and then cooled to room temperature (about 25°C), and dried to obtain thermoplastic starch TPS.

[0114] The chain extender includes the chain extenders shown in Formula I and Formula II, and the chain extenders shown in Formula I and Formula II are mixed in a mass ratio of 1:1;

[0115]

[0116] The preparation method of the chain extender shown in formula I is as follows: terephthalic acid and butanediol are added in a molar ratio of 2:1, tetrabutyl titanate catalyst is added with a mass fraction of 5‰ of the mass of butanediol, and the reaction is carried out at 180°C for 6 hours to prepare PBT with carboxyl groups at both ends. The reaction formula is the same as that in Example 1, wherein the value of m is 3500;

[0117] PBT and 2,2'-bis(2-oxazoline) were added in a molar ratio of 1:2.2, and reacted at 190° C. for 2 hours to obtain a polyester chain extender containing an oxazoline end group as shown in Formula I.

[0118] The preparation method of the chain extender shown in formula II is as follows: adipic acid and butanediol are added in a molar ratio of 2:1, tetrabutyl titanate catalyst is added with a mass fraction of 5‰ of the mass of butanediol, and the reaction is carried out at 180°C for 6h to prepare PBA with carboxyl groups at both ends. The reaction formula is the same as that in Example 1, wherein the value of n is 3500;

[0119] PBA and 2,2'-bis(2-oxazoline) were added in a molar ratio of 1:2.2, and reacted at 190° C. for 2 hours to obtain a polyester chain extender containing an oxazoline end group as shown in Formula II.

[0120] The oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material provided in this comparative example is prepared by:

[0121] PLA, PBAT, thermoplastic starch TPS and chain extender were mixed in a high-speed mixer at 80°C for 20 minutes in a mass ratio of 80:20:30:4, and then sent to a twin-screw extruder. The temperature of the twin-screw extruder was controlled at 180°C, and the screw speed was controlled at 200 rpm. The mixture was extruded and granulated by the twin-screw extruder to obtain an oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material.

[0122] Performance Testing

[0123] The performance of the PLA / PBAT / TPS composite materials provided in the above embodiments and comparative examples was tested.

[0124] The tensile properties were tested using a universal electronic testing machine (DF-101S, High Speed ​​Rail Testing Instrument Co., Ltd.) according to GB / T 1040.3-2006 standard, with a tensile rate of 50 mm / min;

[0125] An impact testing machine (GT-7045-MDL, Shenzhen High Speed ​​Rail Testing Instrument Co., Ltd.) was used to test the notched impact strength according to GB / T 1043-2008 standard, with a pendulum energy of 5.5J.

[0126] The test results are shown in Table 1.

[0127] Table 1

[0128]

[0129]

[0130] It can be seen from the data in Table 1 that compared with the composite materials provided in Comparative Examples 1-4, the tensile strength, elongation at break and impact strength of the composite materials provided in Examples 1-4 of the present invention are significantly improved. It can be seen that the oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite materials provided by the present invention have excellent mechanical properties.

[0131] In Comparative Example 4, the amount of the chain extender in the raw material for preparing the composite material was increased, and it was found that the tensile strength, elongation at break and impact strength of the prepared composite material were reduced.

[0132] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. An oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material, characterized in that: The raw materials include: PLA, PBAT, thermoplastic starch TPS, and chain extender; The thermoplastic starch TPS is starch treated with a plasticizer, wherein the plasticizer comprises a chemical structure of The compounds shown; The chain extender is a polyester chain extender containing an oxazoline terminal group, including chain extenders shown in Formula I and Formula II; 2. The composite material according to claim 1, characterized in that The mass ratio of the PBAT to the PLA is (20-40): (60-80); and / or, the mass ratio of the thermoplastic starch TPS to the PLA is (15-30): (60-80); and / or, the mass ratio of the chain extender to the PLA is (0.5-2): (60-80).

3. The composite material according to claim 1 or 2, characterized in that: The thermoplastic starch TPS is obtained by mixing starch with the plasticizer, wherein the starch and the plasticizer are mixed in a mass ratio of 100:(5-30).

4. The composite material according to claim 3, characterized in that The mixing process comprises: mixing starch with the plasticizer, extruding with a twin-screw extruder, setting the temperature from the first zone to the die head of the twin-screw extruder to 90-130° C., then cooling to 20-40° C., and drying to obtain the thermoplastic starch TPS.

5. The composite material according to claim 1, characterized in that The plasticizer is prepared by using ethyl formate and 4-hydroxybenzenesulfonamide as raw materials, and comprises the steps of: mixing the ethyl formate and the 4-hydroxybenzenesulfonamide in a molar ratio of (1-1.2):(1-1.2), using ethanol as a solvent, stirring and reacting at 40-60° C., and then evaporating the ethanol to obtain the plasticizer.

6. The composite material according to claim 1, characterized in that The chain extender shown in formula I is prepared by reacting PBT with 2,2'-bis(2-oxazoline), comprising the steps of mixing PBT with 2,2'-bis(2-oxazoline) and reacting at 190-200° C. to obtain the chain extender shown in formula I.

7. The composite material according to claim 1, characterized in that The chain extender shown in formula II is prepared by reacting PBA with 2,2'-bis(2-oxazoline), comprising the steps of mixing PBA with 2,2'-bis(2-oxazoline) and reacting at 190-200° C. to obtain the chain extender shown in formula II.

8. A method for preparing the composite material according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: mixing PLA, PBAT, thermoplastic starch TPS and a chain extender, and then feeding the mixture into a twin-screw extruder, wherein the temperature of the twin-screw extruder is controlled at 150-190° C., the screw speed is controlled at 100-300 rpm, and the mixture is extruded and granulated by the twin-screw extruder to obtain an oxazoline-terminated polyester chain-extended PLA / PBAT / TPS composite material.

9. The method for preparing the composite material according to claim 8, characterized in that: The PLA, PBAT, thermoplastic starch TPS and chain extender are mixed in an environment of 60-100° C. for 10-30 minutes.

10. Use of the composite material according to any one of claims 1 to 7 in food containers, medical supplies, packaging films and cling films.

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