Manufacturing Method and Application of a Microwave-Heatable Biodegradable Material

Abstract

The present invention relates to a manufacturing method and application of a microwave-heatable biodegradable material. The microwave-heatable biodegradable material has a heat distortion temperature (0.45 MPa) of 100 - 130 °C, a melting point of 145 - 160 °C, a melt index (190 °C / 2.16 kg) of 4 - 8 g / 10 min, an end carboxyl group content of 8 - 22 mmol / kg, a tensile strength > 35 MPa, an elongation at break > 300%, a flexural strength > 35 MPa, a flexural modulus > 500 MPa, and a relative biodegradation rate in an industrial composting environment over 90 days > 90%. The microwave-heatable biodegradable material has a high melting point and a high softening point, which can meet the high-temperature resistance requirements of microwave heating above 100 °C for tableware in the rail transit and aviation fields. At the same time, the material has high strength and good mechanical properties, and has important application prospects in the fields of aviation straws, forks, boxes, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of degradable materials, and relates to a manufacturing method and application of a microwave-heatable biodegradable material. Background Art

[0002] Existing aviation tableware still uses traditional non-biodegradable polymer materials such as polypropylene (PP) and polyester (PET). Traditional polylactic acid (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) cannot meet the heating temperature resistance requirements of existing aviation tableware due to their low softening temperature and low melting point, resulting in the unusability of existing tableware that needs to be heated in a microwave oven and has a high temperature for holding food, which brings troubles to the low-carbon and environmental protection development of the aviation industry.

[0003] Based on the method for improving the heat resistance stability of materials, by introducing rigid structures such as benzene rings and polycyclic rings in the molecular structure design, the heat resistance stability is improved. However, inevitably, due to the introduction of rigid structures, especially benzene ring structures, the biodegradability of the materials is damaged. The blending processing technology is the most commonly used modification method for polymer materials. Based on the alloy toughening technology, Zhao Mengmeng et al. improved the compatibility of the polylactic acid and polycarbonate alloy by using a reactive comb-shaped molecular solubilizer, and improved the impact resistance and high temperature resistance of polylactic acid. However, polycarbonate itself is a non-biodegradable polymer structure, which affects its biodegradability. Therefore, in order not to change the biodegradability of the materials, the Seiko Group of Japan used biodegradable polyvinyl alcohol as the resin material, and introduced it into the polylactic acid matrix through the crosslinkable characteristics of polyvinyl alcohol to improve the mechanical properties and heat resistance of polylactic acid. At the same time, because polyvinyl alcohol itself has biodegradable properties, its impact on biodegradability is less, but there is also a problem that polyvinyl alcohol crosslinking requires the use of toxic substances such as aldehydes, and the residue in the matrix is difficult to meet the food-grade requirements.

[0004] Aiming at the problems that existing aviation tableware is difficult to biodegrade and conventional biodegradable materials are difficult to meet the high-temperature requirements, the project uses ultraviolet-cured crosslinked materials, and cures and crosslinks PLA and PBAT by ultraviolet light to achieve an increase in the softening point of the materials, and develops a high-temperature biodegradable material that can be heated in a microwave oven, which is of great significance for solving the problem of biodegradable materials for high-temperature aviation tableware in China. Summary of the Invention

[0005] To overcome the deficiencies of existing technical solutions, the present invention provides a manufacturing method and application of a microwave-heatable biodegradable material. The present invention reacts L-serine with biodegradable 1,4-butanediol, which has biodegradable properties, to obtain a bioactive chain extender with four reactive functional groups. The bioactive chain extender is used for solid-phase polycondensation reaction with polybutylene succinate to prepare a star-shaped high-temperature-resistant polybutylene succinate with multiple branches, avoiding the problems that conventional isocyanate chain extenders have biological toxicity and are difficult to degrade, while traditional anhydride and epoxy chain extenders are difficult to biodegrade. At the same time, although the molecular weight increases with a binary functional group structure, the improvement of heat resistance is limited, and excessive cross-linking after multi-functional group chain extension leads to deterioration of mechanical properties and processing performance, making it difficult to meet the melting processing conditions. The microwave-heatable biodegradable material has a high melting point and a high softening point, which can meet the high-temperature resistance requirements for microwave heating of tableware in the rail transit and aviation fields. At the same time, the material has high strength and good mechanical properties, and has important application prospects in the fields of aviation straws, forks, boxes, etc.

[0006] To achieve the above object, the solution adopted by the present invention is as follows:

[0007] A microwave-heatable biodegradable material, characterized in that the heat distortion temperature is 100-130 °C under the condition of 0.45 MPa, the melting point is 145 °C - 160 °C, the melt index is 4-8 g / 10 min under the condition of 190 °C / 2.16 kg, and the end carboxyl group content is 8-22 mmol / kg.

[0008] A microwave-heatable biodegradable material, characterized in that the tensile strength > 35 MPa, the elongation at break > 300%, the flexural strength > 35 MPa, the flexural modulus > 500 MPa, and its relative biodegradation rate in an industrial composting environment for 90 days > 90%.

[0009] A preparation method of a microwave-heatable biodegradable material, characterized by comprising the following technical steps:

[0010] (1) Preparation of the active chain extender

[0011] Using L-serine and 1,4-butanediol as raw materials, put them into a reaction kettle, carry out an esterification reaction in a nitrogen atmosphere, control the water yield of the esterification reaction to be more than 99%, and then remove the excess 1,4-butanediol by vacuum distillation to prepare the active chain extender.

[0012] The molar ratio of L-serine to 1,4-butanediol is 1:1.05 - 1:1.2.

[0013] The temperature of the esterification reaction is 165 °C - 205 °C.

[0014] (2) Preparation of Poly(butylene succinate) Base Slices

[0015] Using succinic acid and 1,4-butanediol as raw materials and tetrabutyl titanate as a catalyst, a stepwise condensation polymerization method is adopted to carry out a stepwise condensation polymerization reaction at 200 - 240 °C, controlling the vacuum degree during the polycondensation process to be 50 - 100 Pa and the reaction time to be 1.5 - 3.0 h; after the reaction is completed, the melt temperature in the polymerization kettle is reduced to 180 - 200 °C, and then an active chain extender is added to the reaction kettle. After melting and stirring for dispersion for 15 - 45 min, extrusion is carried out to obtain poly(butylene succinate) base slices.

[0016] The mass fraction of the chain extender in the poly(butylene succinate) base slices is 0.5 - 5.0 wt%.

[0017] (3) Preparation of Microwave-heatable Biodegradable Materials

[0018] First, the poly(butylene succinate) base slices are dried at 105 °C for 48 h, and the water content of the poly(butylene succinate) base slices is controlled to be below 0.1 wt% to obtain dried poly(butylene succinate) base slices. Then, a solid-phase polycondensation method is adopted, and the dried poly(butylene succinate) base slices are subjected to chain extension and viscosity increase in a solid-phase viscosity-increasing reaction tower to prepare the required microwave-heatable biodegradable materials.

[0019] The solid-phase viscosity-increasing process includes low-temperature viscosity-increasing reaction, medium-temperature viscosity-increasing reaction, high-temperature viscosity-increasing reaction, and negative-pressure viscosity-increasing reaction;

[0020] The low-temperature viscosity-increasing reaction temperature is 105 °C - 110 °C, and the low-temperature viscosity-increasing reaction time is 30 - 120 min;

[0021] The medium-temperature viscosity-increasing reaction temperature is 120 °C - 125 °C, and the medium-temperature viscosity-increasing reaction time is 2 - 5 h;

[0022] The high-temperature viscosity-increasing reaction temperature is 130 °C - 140 °C, and the high-temperature viscosity-increasing reaction time is 4 - 8 h;

[0023] The negative-pressure viscosity-increasing reaction: the negative-pressure viscosity-increasing reaction temperature is 130 °C - 135 °C, the negative-pressure viscosity-increasing reaction vacuum degree is 1000 - 5000 Pa, and the negative-pressure viscosity-increasing reaction time is 30 - 45 min.

[0024] The described microwave-heatable biodegradable materials are prepared by injection molding or extrusion and are used in straws, forks, and box products in the rail transit and aviation fields, and their processing temperature is 200 °C - 220 °C.

[0025] Advantages of the present invention:

[0026] (1) A manufacturing method and application of a microwave-heatable biodegradable material according to the present invention. Aiming at the problems that the softening points of existing aviation tableware materials, especially biodegradable materials based on PBS, PBAT, and PLA, are relatively low and it is difficult to withstand high-temperature steam of 105-120 °C and the microwave heating environment, and the conventional crosslinked structure leads to deterioration of the processing characteristics of the material, such as the melt index in fluidity and mechanical properties, resulting in poor toughness and difficulty in meeting the processing and use requirements. At the same time, the multi-functional group crosslinked structure makes it difficult to biodegrade and affects the biodegradable characteristics. By introducing a biodegradable chain extender structure, especially the amino acid structure required by organisms, into the matrix, the requirements of biodegradable characteristics are met while ensuring the performance required for crosslinking; and the use of a tetra-functional group structure endows a star structure during the reaction process, thus avoiding the problem of embrittlement of mechanical properties caused by excessive crosslinking and ensuring the rheological characteristics during the processing process.

[0027] (2) A manufacturing method and application of a microwave-heatable biodegradable material according to the present invention. Through a solid-phase viscosity-increasing process, a bioactive chain extender with a tetra-functional group is used to carry out solid-phase polycondensation reaction with polybutylene succinate to prepare a star-shaped high-temperature-resistant polybutylene succinate with multiple branches, avoiding the problems that conventional isocyanate-based chain extenders have biological toxicity and are difficult to degrade, while traditional anhydride and epoxy-based chain extenders are difficult to biodegrade. At the same time, although the molecular weight increases with the binary functional group structure, the improvement of heat resistance is limited, and the mechanical properties and processing properties deteriorate due to excessive crosslinking after multi-functional group chain extension, making it difficult to meet the melt processing conditions, etc.; at the same time, by adopting a process of distributed temperature rise and distributed negative pressure during the solid-phase viscosity-increasing process, the adhesion deformation of the polybutylene succinate base slices is avoided by using the distributed temperature, and the small molecules and oligomers can be taken away better and faster by using the negative pressure, thereby further increasing the molecular weight and achieving the purpose of further viscosity increase.

[0028] (3) The microwave-heatable biodegradable material described has a high melting point and a high softening point, which can meet the high-temperature resistance requirements for microwave heating of tableware in the rail transit and aviation fields. At the same time, the material has high strength and good mechanical properties, and has important application prospects in the fields of aviation straws, forks, boxes, etc. Brief Description of the Drawings

[0029] Figure 1 It is the chemical reaction equation of the bioactive chain extender of the present invention;

[0030] Figure 2 It is the NMR spectrum of the bioactive chain extender of the present invention;

[0031] Figure 3 It is the structural schematic diagram of the microwave-heatable biodegradable material of the present invention;

[0032] Figure 4 This is the nuclear magnetic resonance spectrum of the microwave-heatable biodegradable material of the present invention. Detailed implementation manners

[0033] The present invention will be further described below in conjunction with specific implementation manners. It should be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0034] The test methods for each parameter in the present invention are as follows:

[0035] (1) Heat distortion temperature: Tested using an XRW-300 series heat distortion temperature tester according to the method specified in the national standard GB / T 1634.1-2019;

[0036] (2) Melting point: Measured using a Q20 differential scanning calorimeter, with nitrogen as the protective gas, a gas flow rate of 50 mL / min, and a heating rate of 10 °C / min. The maximum melting peak during the heating process is the melting point;

[0037] (3) Melt index: Tested using a Kunshan Hongjin HJ-RRZS melt index tester according to the method of the standard ASTM D 1238;

[0038] (4) Terminal carboxyl group content: Tested using a burette, with phenol and chloroform as solvents, and the volume ratio of the phenol and chloroform solution being 2:3, referring to the national standard GB / T 14190-2017;

[0039] (5) Mechanical properties (tensile strength, elongation at break, flexural strength, flexural modulus): Tested using a Shimadzu AUX-5000 universal testing machine according to the method of the national standard GB1040-2018;

[0040] (6) Biodegradation rate: Tested using a Bipu biodegradation test system according to the method of the national standard GB / T 19277.1-2011.

[0041] Example 1

[0042] A manufacturing method and application of a microwave-heatable biodegradable material. The microwave-heatable biodegradable material has a heat distortion temperature (0.45 MPa) of 100 °C, a melting point of 145 °C, a melt index (190 °C / 2.16 kg) of 8 g / 10 min, an end carboxyl group content of 22 mmol / kg, a tensile strength of 35.5 MPa, an elongation at break of 350%, a flexural strength of 35.9 MPa, a flexural modulus of 510 MPa, and a relative biodegradation rate of 96% in an industrial composting environment for 90 days.

[0043] The preparation method of the microwave-heatable biodegradable material as described above comprises the following steps:

[0044] (1) Preparation of an active chain extender

[0045] Using L-serine and 1,4-butanediol as raw materials, put them into a reaction kettle, carry out an esterification reaction in a nitrogen atmosphere, control the water yield of the esterification reaction to be more than 99%, and then remove the excessive 1,4-butanediol by vacuum distillation to prepare an active chain extender.

[0046] The molar ratio of the L-serine to the 1,4-butanediol is 1:1.25, and the temperature of the esterification reaction is 165 °C.

[0047] (2) Preparation of polybutylene succinate base slices

[0048] Using succinic acid and 1,4-butanediol as raw materials and tetrabutyl titanate as a catalyst, adopt a stepwise condensation polymerization method to carry out a stepwise condensation polymerization reaction at 200 - 240 °C, control the vacuum degree during the polycondensation process to be 50 - 100 Pa, and the reaction time to be 1.5 - 3.0 h; after the reaction is completed, lower the melt temperature in the polymerization kettle to 180 - 200 °C, then add an active chain extender into the reaction kettle, melt and stir for dispersion for 15 - 45 min, and then extrude to obtain polybutylene succinate base slices.

[0049] The mass fraction of the chain extender in the polybutylene succinate base slices is 0.5 wt%.

[0050] (3) Preparation of the microwave-heatable biodegradable material

[0051] First, dry the polybutylene succinate base slices at 105 °C for 48 h, control the water content of the polybutylene succinate base slices to be below 0.1 wt% to obtain dried polybutylene succinate base slices, and then adopt a solid-phase polycondensation method to carry out chain extension and viscosity increase of the dried polybutylene succinate base slices in a solid-phase viscosity-increasing reaction tower to prepare the required microwave-heatable biodegradable material.

[0052] The solid-phase viscosity-increasing process described above includes low-temperature viscosity-increasing reaction, medium-temperature viscosity-increasing reaction, high-temperature viscosity-increasing reaction, and negative-pressure viscosity-increasing reaction; the temperature of the low-temperature viscosity-increasing reaction is 105°C, and the time of the low-temperature viscosity-increasing reaction is 120 min; the temperature of the medium-temperature viscosity-increasing reaction is 120°C, and the time of the medium-temperature viscosity-increasing reaction is 5 h; the temperature of the high-temperature viscosity-increasing reaction is 130°C, and the time of the high-temperature viscosity-increasing reaction is 8 h; for the negative-pressure viscosity-increasing reaction, the temperature is 130°C, the vacuum degree is 1000 Pa, and the time is 45 min.

[0053] The microwave-heatable biodegradable material described above is injection-molded to obtain microwave-heatable forks and boxes, with a processing temperature of 210°C, and is extrusion-molded to obtain microwave-heatable straws with a processing temperature of 200°C.

[0054] Example 2

[0055] A manufacturing method and application of a microwave-heatable biodegradable material in the present application. The microwave-heatable biodegradable material has a heat distortion temperature (0.45 MPa) of 130°C, a melting point of 160°C, a melt index (190°C / 2.16 kg) of 8 g / 10 min, an end carboxyl group content of 8 mmol / kg, a tensile strength of 36 MPa, an elongation at break of 350%, a flexural strength of 37.8 MPa, a flexural modulus of 550 MPa, and a relative biodegradation rate of 95% in an industrial composting environment for 90 days.

[0056] The preparation method of the microwave-heatable biodegradable material as described above includes the following steps:

[0057] (1) Preparation of an active chain extender

[0058] Using L-serine and 1,4-butanediol as raw materials, put them into a reaction kettle, carry out an esterification reaction in a nitrogen atmosphere, control the water yield of the esterification reaction to be more than 99%, and then remove the excessive 1,4-butanediol by vacuum distillation to prepare an active chain extender.

[0059] The molar ratio of the L-serine and 1,4-butanediol is 1:1.05, and the temperature of the esterification reaction is 205°C.

[0060] (2) Preparation of polybutylene succinate base chips

[0061] Using succinic acid and 1,4-butanediol as raw materials and tetrabutyl titanate as a catalyst, a stepwise condensation polymerization method is adopted to carry out a stepwise condensation polymerization reaction at 200-240 °C, controlling the vacuum degree during the polycondensation process to be 50-100 Pa and the reaction time to be 1.5-3.0 h; after the reaction is completed, the melt temperature in the polymerization kettle is reduced to 180-200 °C, and then an active chain extender is added to the reaction kettle. After melting, stirring and dispersing for 15-45 min, extrusion is carried out to obtain polybutylene succinate base chips.

[0062] The mass fraction of the chain extender in the polybutylene succinate base chips is 5.0 wt%.

[0063] (3) Preparation of microwave-heatable biodegradable materials

[0064] First, the polybutylene succinate base chips are dried at 105 °C for 48 h, and the moisture content of the polybutylene succinate base chips is controlled to be below 0.1 wt% to obtain dried polybutylene succinate base chips. Then, a solid-phase polycondensation method is adopted, and the dried polybutylene succinate base chips are subjected to chain extension and viscosity increase in a solid-phase viscosity-increasing reaction tower to obtain the required microwave-heatable biodegradable materials.

[0065] The solid-phase viscosity-increasing process includes a low-temperature viscosity-increasing reaction, a medium-temperature viscosity-increasing reaction, a high-temperature viscosity-increasing reaction, and a negative-pressure viscosity-increasing reaction; the temperature of the low-temperature viscosity-increasing reaction is 110 °C, and the time of the low-temperature viscosity-increasing reaction is 120 min; the temperature of the medium-temperature viscosity-increasing reaction is 125 °C, and the temperature of the medium-temperature viscosity-increasing reaction is 2 h; the temperature of the high-temperature viscosity-increasing reaction is 140 °C, and the time of the high-temperature viscosity-increasing reaction is 4 h; the negative-pressure viscosity-increasing reaction is that the temperature of the negative-pressure viscosity-increasing reaction is 135 °C, the vacuum degree of the negative-pressure viscosity-increasing reaction is 5000 Pa, and the time of the negative-pressure viscosity-increasing reaction is 30 min.

[0066] The microwave-heatable biodegradable materials are injection-molded to obtain microwave-heatable forks and boxes, and their processing temperature is 220 °C. The microwave-heatable straws obtained by extrusion molding have a processing temperature of 210 °C.

[0067] Example 3

[0068] For a manufacturing method and application of a microwave-heatable biodegradable material in this application, the microwave-heatable biodegradable material has a heat distortion temperature (0.45 MPa) of 130 °C, a melting point of 155 °C, a melt index (190 °C / 2.16 kg) of 5 g / 10 min, an end carboxyl group content of 10 mmol / kg, a tensile strength of 37.4 MPa, an elongation at break of 450%, a flexural strength of 39.2 MPa, a flexural modulus of 6500 MPa, and a relative biodegradation rate of 95% in an industrial composting environment for 90 days.

[0069] The preparation method of the microwave-heatable biodegradable material as described above comprises the following steps:

[0070] (1) Preparation of the reactive chain extender

[0071] Using L-serine and 1,4-butanediol as raw materials, put them into a reaction kettle, and carry out an esterification reaction in a nitrogen atmosphere. Control the water yield of the esterification reaction to be over 99%, and then remove the excessive 1,4-butanediol by vacuum distillation to prepare the reactive chain extender.

[0072] The molar ratio of the L-serine to the 1,4-butanediol is 1:1.15, and the temperature of the esterification reaction is 195°C.

[0073] (2) Preparation of the polybutylene succinate base chips

[0074] Using succinic acid and 1,4-butanediol as raw materials and tetrabutyl titanate as a catalyst, adopt the method of stepwise condensation polymerization, carry out the stepwise condensation polymerization reaction at 200 - 240°C, control the vacuum degree during the polycondensation process to be 50 - 100 Pa, and the reaction time to be 1.5 - 3.0 h; after the reaction ends, lower the melt temperature in the polymerization kettle to 180 - 200°C, then add the reactive chain extender into the reaction kettle, stir and disperse it for 15 - 45 min and then extrude to obtain the polybutylene succinate base chips.

[0075] The mass fraction of the chain extender in the polybutylene succinate base chips is 4.0 wt%.

[0076] (3) Preparation of the microwave-heatable biodegradable material

[0077] First, dry the polybutylene succinate base chips at 105°C for 48 h, control the moisture content of the polybutylene succinate base chips to be below 0.1 wt% to obtain the dried polybutylene succinate base chips, and then adopt the method of solid-phase polycondensation. The dried polybutylene succinate base chips are subjected to chain extension and viscosity increase in a solid-phase viscosity increase reaction tower to prepare the required microwave-heatable biodegradable material.

[0078] The solid-phase viscosity increase process includes a low-temperature viscosity increase reaction, a medium-temperature viscosity increase reaction, a high-temperature viscosity increase reaction, and a negative-pressure viscosity increase reaction; the temperature of the low-temperature viscosity increase reaction is 110°C, and the time of the low-temperature viscosity increase reaction is 120 min; the temperature of the medium-temperature viscosity increase reaction is 125°C, and the time of the medium-temperature viscosity increase reaction is 5 h; the temperature of the high-temperature viscosity increase reaction is 140°C, and the time of the high-temperature viscosity increase reaction is 8 h; the negative-pressure viscosity increase reaction is that the temperature of the negative-pressure viscosity increase reaction is 135°C, the vacuum degree of the negative-pressure viscosity increase reaction is 1000 Pa, and the time of the negative-pressure viscosity increase reaction is 45 min.

[0079] The described microwave-heatable biodegradable material is injection-molded to obtain microwave-heatable forks and boxes, with a processing temperature of 210°C. The microwave-heatable straws obtained by extrusion molding have a processing temperature of 210°C.

[0080] Figure 1 It is the chemical reaction equation for the preparation of the reactive chain extender. Figure 2 It is the hydrogen spectrum of the nuclear magnetic resonance spectrum of the reactive chain extender. The chemical shift structures corresponding to a (4.20 - 4.28 ppm) and b (3.98 - 4.08 ppm) are the characteristic peaks of the ethyl group. The peak at c (3.51 - 3.55 ppm) is the characteristic peak of the hydroxyl group structure or the electron-withdrawing group. At the same time, the peak at d (1.99 - 2.02 ppm) is the characteristic peak of the hydroxyl group structure or the amino group structure, and the peak at e (1.48 - 1.57 ppm) is the ethyl functional group in the alkane. The characteristic peak of the carboxylic acid disappears in the spectrum, and there are a large number of characteristic peaks of the hydroxyl group structure in the spectrum, indicating that L-serine and 1,4-butanediol have reacted. At the same time, the unique ethyl functional group e in the 1,4-butanediol framework is observed in the spectrum, and a multiple splitting peak structure appears in the functional group. Therefore, it is also confirmed that L-serine and 1,4-butanediol have reacted. At the same time, through the analysis of the peak area ratio of the characteristic peaks a, b, and e, the ratio of the sum of the peak areas Sab of a and b to the peak area Se of e, Sab:Se, is 1:1.01. Therefore, it shows that L-serine and 1,4-butanediol have reacted in a 1:1 ratio, indicating that the synthesized compound is the required reactive chain extender.

[0081] Figure 3 It is the schematic diagram of the molecular structure of the microwave-heatable biodegradable material. Figure 4 It is the nuclear magnetic resonance spectrum of the microwave-heatable biodegradable material. The peak at 2.64 ppm corresponds to the characteristic absorption peak of the ethyl structure on succinic acid in PBS. At the same time, the peak at 5.02 ppm in the spectrum is the characteristic peak of the hydrogen nuclear magnetic resonance spectrum unique to the reactive chain extender, corresponding to the characteristic peak structure of the α-H structure connected to the carbonyl group (C=O) and the amino group in the reactive chain extender. At the same time, the amino characteristic peak in the structure of the reactive chain extender is not found in the spectrum. Therefore, it shows that the reactive chain extender has undergone a chain extension reaction with polybutylene succinate (PBS), and at the same time, the amino groups (-NH2) on the original chain extender have all undergone a chain extension reaction, and the corresponding reactive chain extender reacts with PBS to form a star structure. By comparing the characteristic peak area S1 at 2.64 ppm and the characteristic peak area S2 at 5.02 ppm, the ratio of S2:S1 is obtained as 1:101. Since the ethyl group corresponds to 4 hydrogens and the chain extender corresponds to 1 hydrogen, and the addition amount of the chain extender is 4.0%, it shows that the theoretical ratio of S2:S1 is 1:100. Therefore, it is close to the obtained peak area, indicating that the chain extender reacts with PBS to form a material with a star structure, which is the designed Figure 3 Molecular structure of the microwave-heatable biodegradable material.

[0082] Example 4

[0083] A manufacturing method and application of a microwave-heatable biodegradable material according to the present application. The microwave-heatable biodegradable material has a heat distortion temperature (0.45 MPa) of 120 °C, a melting point of 150 °C, a melt index (190 °C / 2.16 kg) of 6 g / 10 min, an end carboxyl group content of 18 mmol / kg, a tensile strength of 36.2 MPa, an elongation at break of 380%, a flexural strength of 35.9 MPa, a flexural modulus of 550 MPa, and a relative biodegradation rate of 96% in an industrial composting environment for 90 days.

[0084] The preparation method of the microwave-heatable biodegradable material as described above comprises the following steps:

[0085] (1) Preparation of an active chain extender

[0086] Using L-serine and 1,4-butanediol as raw materials, put them into a reaction kettle, and carry out an esterification reaction in a nitrogen atmosphere. Control the water yield of the esterification reaction to be more than 99%, and then remove the excessive 1,4-butanediol by vacuum distillation to prepare the active chain extender.

[0087] The molar ratio of the L-serine to the 1,4-butanediol is 1:1.20, and the temperature of the esterification reaction is 200 °C.

[0088] (2) Preparation of polybutylene succinate base slices

[0089] Using succinic acid and 1,4-butanediol as raw materials and tetrabutyl titanate as a catalyst, adopt a stepwise condensation polymerization method to carry out a stepwise condensation polymerization reaction at 200 - 240 °C. Control the vacuum degree during the polycondensation process to be 50 - 100 Pa, and the reaction time to be 1.5 - 3.0 h; after the reaction is completed, lower the melt temperature in the polymerization kettle to 180 - 200 °C, then add the active chain extender into the reaction kettle, melt and stir for dispersion for 15 - 45 min, and then extrude to obtain polybutylene succinate base slices.

[0090] The mass fraction of the chain extender in the polybutylene succinate base slices is 5.0 wt%.

[0091] (3) Preparation of the microwave-heatable biodegradable material

[0092] First, the polybutylene succinate base chips are dried at 105 °C for 48 h, and the moisture content of the polybutylene succinate base chips is controlled to be below 0.1 wt%, so as to obtain the dried polybutylene succinate base chips. Then, by using the method of solid-phase polycondensation, the dried polybutylene succinate base chips are subjected to chain extension and viscosity increase in a solid-phase viscosity-increasing reaction tower, so as to obtain the required microwave-heatable biodegradable material.

[0093] The solid-phase viscosity-increasing process includes a low-temperature viscosity-increasing reaction, a medium-temperature viscosity-increasing reaction, a high-temperature viscosity-increasing reaction, and a negative-pressure viscosity-increasing reaction; the temperature of the low-temperature viscosity-increasing reaction is 110 °C, and the time of the low-temperature viscosity-increasing reaction is 90 min; the temperature of the medium-temperature viscosity-increasing reaction is 120 °C, and the time of the medium-temperature viscosity-increasing reaction is 5 h; the temperature of the high-temperature viscosity-increasing reaction is 135 °C, and the time of the high-temperature viscosity-increasing reaction is 6 h; the negative-pressure viscosity-increasing reaction is that the temperature of the negative-pressure viscosity-increasing reaction is 135 °C, the vacuum degree of the negative-pressure viscosity-increasing reaction is 1000 Pa, and the time of the negative-pressure viscosity-increasing reaction is 45 min.

[0094] The microwave-heatable biodegradable material is injection-molded to obtain microwave-heatable tableware forks and boxes, and its processing temperature is 210 °C, and the microwave-heatable straws obtained by extrusion molding have a processing temperature of 200 °C.

[0095] Example 5

[0096] A manufacturing method and application of a microwave-heatable biodegradable material, the microwave-heatable biodegradable material has a heat distortion temperature (0.45 MPa) of 125 °C, a melting point of 160 °C, a melt index (190 °C / 2.16 kg) of 5 g / 10 min, an end carboxyl group content of 12 mmol / kg, a tensile strength of 35.9 MPa, an elongation at break of 360%, a flexural strength of 37.0 MPa, a flexural modulus of 540 MPa, and a relative biodegradation rate of 95% in an industrial composting environment for 90 days.

[0097] The preparation method of the microwave-heatable biodegradable material as described above comprises the following steps:

[0098] (1) Preparation of the active chain extender

[0099] Using L-serine and 1,4-butanediol as raw materials, putting them into a reaction kettle, carrying out an esterification reaction in a nitrogen atmosphere, controlling the water yield of the esterification reaction to be above 99%, and then removing the excessive 1,4-butanediol by vacuum distillation to obtain the active chain extender.

[0100] The molar ratio of the L-serine to the 1,4-butanediol is 1:1.15, and the temperature of the esterification reaction is 200 °C.

[0101] (2) Preparation of the polybutylene succinate base chips

[0102] Using succinic acid and 1,4-butanediol as raw materials and tetrabutyl titanate as a catalyst, a stepwise condensation polymerization method is adopted to carry out a stepwise condensation polymerization reaction at 200-240 °C. The vacuum degree during the polycondensation process is controlled at 50-100 Pa, and the reaction time is 1.5-3.0 h. After the reaction is completed, the melt temperature in the polymerization kettle is lowered to 180-200 °C, and then an active chain extender is added to the reaction kettle. After melting, stirring and dispersing for 15-45 min, extrusion is carried out to obtain polybutylene succinate base chips.

[0103] The mass fraction of the chain extender in the polybutylene succinate base chips is 4.5 wt%.

[0104] (3) Preparation of microwave-heatable biodegradable materials

[0105] First, the polybutylene succinate base chips are dried at 105 °C for 48 h, and the water content of the polybutylene succinate base chips is controlled below 0.1 wt% to obtain dried polybutylene succinate base chips. Then, a solid-phase polycondensation method is adopted, and the dried polybutylene succinate base chips are subjected to chain extension and viscosity increase in a solid-phase viscosity-increasing reaction tower to obtain the required microwave-heatable biodegradable materials.

[0106] The solid-phase viscosity-increasing process includes a low-temperature viscosity-increasing reaction, a medium-temperature viscosity-increasing reaction, a high-temperature viscosity-increasing reaction, and a negative-pressure viscosity-increasing reaction; the temperature of the low-temperature viscosity-increasing reaction is 110 °C, and the time of the low-temperature viscosity-increasing reaction is 90 min; the temperature of the medium-temperature viscosity-increasing reaction is 125 °C, and the time of the medium-temperature viscosity-increasing reaction is 5 h; the temperature of the high-temperature viscosity-increasing reaction is 140 °C, and the time of the high-temperature viscosity-increasing reaction is 6 h; the negative-pressure viscosity-increasing reaction is that the temperature of the negative-pressure viscosity-increasing reaction is 135 °C, the vacuum degree of the negative-pressure viscosity-increasing reaction is 1000 Pa, and the time of the negative-pressure viscosity-increasing reaction is 45 min.

[0107] The microwave-heatable biodegradable materials are injection-molded to obtain microwave-heatable forks and boxes, and their processing temperature is 220 °C. The microwave-heatable straws obtained by extrusion molding have a processing temperature of 210 °C.

[0108] Comparative Example 1

[0109] Basically the same as Example 3, the difference is that in step (1), L-serine is directly used as the structure of the chain extender.

[0110] Since the chain extender contains a carboxylic acid structure in its molecular structure, during the melt extrusion and processing process, the PBS chips are severely decomposed in an acidic high-temperature environment, resulting in difficulty in obtaining polybutylene succinate base chips.

[0111] Comparative Example 2

[0112] Basically the same as Example 3, the only difference being that in step (1), butanediol is replaced with butanol.

[0113] In the polybutylene succinate base slice and the material described, the mechanical properties of the material are 22.5 MPa, the heat distortion temperature is 105 °C, and the biodegradability performance test is 56%. Since butanol is easily removed during the preparation process, it is extremely easy to become inactivated during the viscosity increase process, resulting in hindrance to the PBS viscosity increase process. At the same time, the unreacted butanol structure itself is not biodegradable, and there are differences in the alcohol structure between the material and the PBS matrix, so it will have an impact on its biodegradability performance.

[0114] Comparative Example 3

[0115] Basically the same as Example 3, the difference being that in step (3), vacuum negative pressure viscosity increase reaction is not adopted; the obtained material has a heat distortion temperature of 80 °C, a melt index of 10 g / 10 min, an end carboxyl group content of 20 mmol / kg, a tensile strength of 25 MPa, an elongation at break of 300%, a flexural strength of 20 MPa, and a flexural modulus of 400 MPa. Its relative biodegradation rate in an industrial composting environment for 90 days is 95%. Although the material has certain mechanical properties, due to the lack of the vacuum negative pressure viscosity increase process, there are more oligomers inside, resulting in limited increase in the heat distortion temperature of the material, and due to the influence of the internal oligomers, the mechanical properties of the material are not ideal and have a relatively serious reduction.

[0116] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be considered within the protection scope of the present invention.

Claims

1. A preparation method of a microwave-heatable biodegradable material, characterized in that, It includes the following technical steps: (1) Preparation of the active chain extender Using L-serine and 1,4-butanediol as raw materials, put them into a reaction kettle, carry out an esterification reaction in a nitrogen atmosphere, control the water yield of the esterification reaction to be more than 99%, and then remove the excessive 1,4-butanediol by vacuum distillation to prepare the active chain extender; (2) Preparation of the poly(butylene succinate) base slice Using succinic acid and 1,4-butanediol as raw materials and tetrabutyl titanate as a catalyst, adopt the method of stepwise condensation polymerization, carry out stepwise condensation polymerization reaction at 200-240 °C, control the vacuum degree during the polycondensation process to be 50-100 Pa, and the reaction time to be 1.5-3.0 h; after the reaction is completed, lower the melt temperature in the polymerization kettle to 180-200 °C, then add the active chain extender into the reaction kettle, and after melting, stirring and dispersing for 15-45 min, carry out extrusion to obtain the poly(butylene succinate) base slice; (3) Preparation of the microwave-heatable biodegradable material First, dry the poly(butylene succinate) base slice at 105 °C for 48 h, control the water content of the poly(butylene succinate) base slice to be below 0.1 wt% to obtain the dried poly(butylene succinate) base slice, and then adopt the method of solid-phase polycondensation. The dried poly(butylene succinate) base slice is subjected to chain extension and viscosity increase in a solid-phase viscosity-increasing reaction tower to prepare the required microwave-heatable biodegradable material; The solid-phase viscosity-increasing process includes a low-temperature viscosity-increasing reaction, a medium-temperature viscosity-increasing reaction, a high-temperature viscosity-increasing reaction and a negative-pressure viscosity-increasing reaction; The temperature of the low-temperature viscosity-increasing reaction is 105 °C - 110 °C, and the time of the low-temperature viscosity-increasing reaction is 30 - 120 min; The temperature of the medium-temperature viscosity-increasing reaction is 120 °C - 125 °C, and the time of the medium-temperature viscosity-increasing reaction is 2 - 5 h; The temperature of the high-temperature viscosity-increasing reaction is 130 °C - 140 °C, and the time of the high-temperature viscosity-increasing reaction is 4 - 8 h; The temperature of the negative-pressure viscosity-increasing reaction is 130 °C - 135 °C, the vacuum degree of the negative-pressure viscosity-increasing reaction is 1000 - 5000 Pa, and the time of the negative-pressure viscosity-increasing reaction is 30 - 45 min.

2. The preparation method of a microwave-heatable biodegradable material according to claim 1, characterized in that, In step (1), the molar ratio of L-serine to 1,4-butanediol is 1:1.05 - 1:1.

2.

3. The preparation method of a microwave-heatable biodegradable material according to claim 1, characterized in that, In step (1), the temperature of the esterification reaction is 165 °C - 205 °C.

4. The preparation method of a microwave-heatable biodegradable material according to claim 1, characterized in that, In step (2), the mass fraction of the chain extender in the poly(butylene succinate) base slice is 0.5 - 5.0 wt%.

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