Preparation method of glycolide modified PBAT

Abstract

The invention relates to the technical field of high polymer materials, in particular to a preparation method of glycolide modified PBAT (poly (butyleneadipate-co-terephthalate)), which comprises the following steps: adding adipic acid, 1, 4-butanediol, terephthalic acid, glycolide and a catalyst into a reaction kettle, introducing nitrogen for replacement, heating to a first preset temperature, and carrying out primary esterification reaction; continuously raising the temperature to a second preset temperature and carrying out a second esterification reaction; raising the temperature to a third preset temperature, adding a catalyst and a heat stabilizer, and carrying out a pre-polycondensation reaction in a first vacuum environment; and after the pre-polycondensation reaches the end point, heating to a fourth preset temperature, and carrying out polycondensation reaction in a second vacuum environment to obtain the glycolide modified PBAT material. The preparation method of the glycolide modified PBAT aims at solving the problem that the natural degradation rate of the PBAT is slow.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a method for preparing glycolide-modified PBAT. Background Art

[0002] Degradable materials are materials that can be degraded both in the thermodynamic and kinetic sense, such as photodegradable materials that are degraded by sunlight; biodegradable materials that are degraded into carbon dioxide and water by the respiration or chemosynthesis of natural microorganisms such as fungi and bacteria; environmentally degradable materials that are degraded under natural environmental conditions, including polylactic acid, starch plastics, polyvinyl alcohol, ethylene / carbon monoxide copolymers, etc. As environmental pollution problems become increasingly severe, the development of new and efficient degradable materials has become a research hotspot.

[0003] Degradable polyester materials have been widely used, such as films, foam materials, injection molded parts, etc. Such materials have good physical properties and can be degraded into water and carbon dioxide in compost or natural state, without potential harm to the environment. Among them, polybutylene adipate terephthalate resin (PBAT) is one of the most active degradable materials in the current research of biodegradable plastics, but PBAT has the problem of slow natural degradation rate. At present, the modification of PBAT is concentrated on blending modification, mainly by doping some bio-based biodegradable materials with faster degradation rates such as polyglycolide, polycaprolactone, polylactide (polylactic acid) in PBAT, but this method improves the degradation rate of the overall material, and the degradation rate of PBAT in the blended material is not improved.

[0004] Therefore, the inventors provide a method for preparing glycolide-modified PBAT. Summary of the invention

[0005] (1) Technical issues to be resolved The embodiment of the present invention provides a method for preparing glycolide-modified PBAT, which solves the technical problem of slow natural degradation rate of PBAT.

[0006] (2) Technical solution The present invention provides a method for preparing glycolide-modified PBAT, comprising the following steps: Adipic acid, 1,4-butanediol, terephthalic acid, glycolide and a catalyst are added into a reaction kettle, nitrogen is introduced for replacement, and then heated to a first preset temperature for a first esterification reaction; Continue to raise the temperature to a second preset temperature to carry out a second esterification reaction; Raising the temperature to a third preset temperature, adding the catalyst and the heat stabilizer, and performing a pre-polycondensation reaction under a first vacuum environment; After the pre-polycondensation reaches the end point, the temperature is raised to a fourth preset temperature and a polycondensation reaction is carried out under a second vacuum environment to obtain a glycolide-modified PBAT material.

[0007] Furthermore, the molar ratio of the 1,4-butanediol, the adipic acid, the terephthalic acid and the glycolide is 1.2:0.4:0.6:0.2.

[0008] Furthermore, the first preset temperature is 150-180°C.

[0009] Furthermore, the second preset temperature is 180-200°C.

[0010] Furthermore, the third preset temperature is 200-240°C.

[0011] Furthermore, the fourth preset temperature is 245-250°C.

[0012] Furthermore, the catalyst is a mixture of tetrabutyl titanate and stannous octoate.

[0013] Furthermore, the added amount of the tetrabutyl titanate is 5‰ of the acid mass, and the acid mass is the total mass of the adipic acid and the terephthalic acid.

[0014] Furthermore, the amount of stannous octoate added is 4.5-7.5‰ of the acid mass, and the acid mass is the total mass of the adipic acid and the terephthalic acid.

[0015] Furthermore, in the pre-polycondensation reaction, the mass ratio of the heat stabilizer to the catalyst is (0.5-1.0):1.0.

[0016] (3) Beneficial effects In summary, the present invention introduces a polyglycolide (PGA) segment into the PBAT structure through copolymerization modification. The flexible segment reduces the crystallinity of the material by destroying the sequence structure of PBAT, thereby improving the elongation at break of the material while maintaining the basic properties of PBAT. There is only one methylene group between the two ester groups in the PGA segment, which has a greater electron-withdrawing effect. Compared with the ester groups in PBAT, the ester groups in the PGA segment are more easily attacked and broken, and the PGA segment is a fatty ester with better hydrophilicity. The introduction of the polyglycolide segment makes the aromatic ester (polybutylene terephthalate) more dispersed in the overall structure, so the degradation rate of the synthetic polyester material is also improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments of the present invention are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 1 is a schematic flow chart of a method for preparing glycolide-modified PBAT provided in an embodiment of the present invention; Figure 2 It is an experimental reaction mechanism diagram of a method for preparing glycolide-modified PBAT provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The following detailed description of the embodiments of the present invention is provided in conjunction with the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention, but cannot be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments.

[0020] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0021] Figure 1 is a schematic diagram of a process for preparing a glycolide-modified PBAT according to an embodiment of the present invention, see Figure 1 , the method may include the following steps: S100, adding adipic acid, 1,4-butanediol, terephthalic acid, glycolide and a catalyst into a reaction kettle, introducing nitrogen to replace the reaction kettle, and heating the reaction kettle to a first preset temperature to perform a first esterification reaction.

[0022] Specifically, the molar ratio of 1,4-butanediol, adipic acid, terephthalic acid and glycolide is 1.2:0.4:0.6:0.2. The catalyst is a mixture of tetrabutyl titanate and stannous octoate, and the amount of tetrabutyl titanate added is 5‰ of the total mass of adipic acid and terephthalic acid. The amount of stannous octoate added is 4.5-7.5‰ of the total mass of adipic acid and terephthalic acid. Furthermore, the first preset temperature is 150-180°C.

[0023] When the first esterification reaction starts, water is generated. The temperature of the reflux pipe of the reactor starts to rise, the esterification water starts to distill out, the temperature of the reflux pipe drops, and the first esterification reaction is completed.

[0024] S200, continue to raise the temperature to a second preset temperature to perform a second esterification reaction.

[0025] Specifically, in the secondary esterification step, the temperature is heated to 180-200° C., water is generated by the reaction, the temperature of the reflux pipe begins to rise, the esterified water begins to distill out, the temperature of the reflux pipe decreases, and the second esterification is completed.

[0026] S300, raising the temperature to a third preset temperature, adding a catalyst and a thermal stabilizer, and performing a pre-polycondensation reaction under a first vacuum environment.

[0027] Specifically, the catalyst is a mixture of tetrabutyl titanate and stannous octoate, and the amount of tetrabutyl titanate added is 5‰ of the total mass of adipic acid and terephthalic acid. The amount of stannous octoate added is 4.5-7.5‰ of the total mass of adipic acid and terephthalic acid. The vacuum is controlled at 2-6 kPa to perform a pre-condensation reaction. When the characteristic viscosity of the feed liquid changes significantly, it is the end point of the pre-condensation reaction.

[0028] Furthermore, the third preset temperature is 200-240° C., the thermal stabilizer is triphenyl phosphate, and the mass ratio of the thermal stabilizer to the catalyst is (0.5-1.0):1.0.

[0029] S400, after the pre-polycondensation reaches an end point, the temperature is raised to a fourth preset temperature and a polycondensation reaction is performed under a second vacuum environment to obtain a glycolide-modified PBAT material.

[0030] Specifically, the fourth preset temperature is 245-250°C, and the temperature is slowly pumped to a high vacuum, and the vacuum is controlled to be below 200Pa. When the "pole climbing" phenomenon occurs, it is the end point of the reaction, and the glycolide-modified PBAT material is obtained.

[0031] In addition, the reaction mechanism between adipic acid, 1,4-butanediol, terephthalic acid, and glycolide is as follows Figure 2 As shown, terephthalic acid (PTA) and 1,4-butanediol (BDO) undergo a first esterification reaction to generate a corresponding first product, adipic acid (AA) and 1,4-butanediol (BDO) undergo a second esterification reaction to generate a corresponding second product, glycolide is hydrolyzed to generate a corresponding third product, and then a final polycondensation reaction occurs between the first product, the second product and the third product to generate glycolide-modified PBAT.

[0032] Example 1 Primary esterification: 1,4-butanediol, adipic acid, terephthalic acid, and glycolide were added to a reactor equipped with a heating device, a stirrer, a reflux tube, and a condenser according to a molar ratio of 1.2:0.4:0.6:0.2, and a catalyst (tetrabutyl titanate, 5‰ of the acid mass; stannous octoate, 5.5‰ of the acid mass) was added. After nitrogen was introduced for replacement, the mixture was heated to 150°C, and the reaction began to generate water. The temperature of the reflux tube began to rise, and the esterified water began to distill out. The temperature of the reflux tube dropped, indicating that the first esterification reaction was completed.

[0033] Secondary esterification: Heat to 180℃ for the second esterification. The reaction generates water, the reflux tube temperature begins to rise, the esterified water begins to distill out, and the reflux tube temperature drops, indicating that the second esterification is completed.

[0034] Pre-condensation: raise the temperature to 200°C, add catalyst (tetrabutyl titanate, 5‰ of acid mass; stannous octoate, 4.5‰ of acid mass), heat stabilizer triphenyl phosphate (mass ratio of heat stabilizer to catalyst is 0.7:1.0), slowly evacuate and control the vacuum to 2kPa, and carry out pre-condensation reaction. When the characteristic viscosity of the feed liquid changes significantly, it is the end point of the reaction.

[0035] Final polycondensation: After the pre-shrinkage reaches the end point, the temperature is raised to 245°C for polycondensation reaction, and the vacuum is slowly evacuated to high vacuum, and the vacuum is controlled below 200Pa. When the "pole climbing" phenomenon occurs, it is the end point of the reaction, and glycolide-modified PBAT is obtained.

[0036] The biodegradation percentage of the glycolide-modified PBAT prepared in Example 1 after 60 days of composting was 78%, as shown in Table 1 below.

[0037] Example 2 Primary esterification: 1,4-butanediol, adipic acid, terephthalic acid, and glycolide were added to a reactor equipped with a heating device, a stirrer, a reflux tube, and a condenser according to a molar ratio of 1.2:0.4:0.6:0.2, and a catalyst (tetrabutyl titanate, 5‰ of the acid mass; stannous octoate, 5.5‰ of the acid mass) was added. After nitrogen substitution, the mixture was heated to 180°C, and the reaction began to generate water. The temperature of the reflux tube began to rise, and the esterified water began to distill out. The temperature of the reflux tube dropped, indicating that the first esterification reaction was completed.

[0038] Secondary esterification: Heat to 200℃ for the second esterification. The reaction generates water, the reflux tube temperature begins to rise, the esterified water begins to distill out, and the reflux tube temperature drops, indicating that the second esterification is completed.

[0039] Pre-condensation: Raise the temperature to 240°C, add catalyst (tetrabutyl titanate, 5‰ of the acid mass; stannous octoate, 7.5‰ of the acid mass), heat stabilizer triphenyl phosphate (the mass ratio of heat stabilizer to catalyst is 0.7:1.0), slowly evacuate and control the vacuum to 6kPa, and carry out pre-condensation reaction. When the characteristic viscosity of the feed liquid changes significantly, it is the end point of the reaction.

[0040] Final polycondensation: After the pre-shrinkage reaches the end point, the temperature is raised to 250°C for polycondensation reaction, and the temperature is slowly evacuated to high vacuum, and the vacuum is controlled below 200Pa. When the "pole climbing" phenomenon occurs, it is the end point of the reaction, and glycolide-modified PBAT is obtained.

[0041] The biodegradation percentage of the glycolide-modified PBAT prepared in Example 2 after 60 days of composting was 85%, as shown in Table 1 below.

[0042] Example 3 Primary esterification: 1,4-butanediol, adipic acid, terephthalic acid, and glycolide were added to a reactor equipped with a heating device, a stirrer, a reflux tube, and a condenser according to a molar ratio of 1.2:0.4:0.6:0.2, and a catalyst (tetrabutyl titanate, 5‰ of the acid mass; stannous octoate, 5.5‰ of the acid mass) was added. After nitrogen was introduced for replacement, the mixture was heated to 165°C, and the reaction began to generate water. The temperature of the reflux tube began to rise, and the esterified water began to distill out. The temperature of the reflux tube dropped, indicating that the first esterification reaction was completed.

[0043] Secondary esterification: Heat to 190℃ for the second esterification. The reaction generates water, the reflux tube temperature begins to rise, the esterified water begins to distill out, and the reflux tube temperature drops, indicating that the second esterification is completed.

[0044] Pre-condensation: raise the temperature to 220°C, add catalyst (tetrabutyl titanate, 5‰ of the acid mass; stannous octoate, 4.5‰ of the acid mass), heat stabilizer triphenyl phosphate (the mass ratio of heat stabilizer to catalyst is 0.7:1.0), slowly evacuate and control the vacuum to 4kPa, and carry out pre-condensation reaction. When the characteristic viscosity of the feed liquid changes significantly, it is the end point of the reaction.

[0045] Final polycondensation: After the pre-shrinkage reaches the end point, the temperature is raised to 245°C for polycondensation reaction, and the vacuum is slowly evacuated to high vacuum, and the vacuum is controlled below 200Pa. When the "pole climbing" phenomenon occurs, it is the end point of the reaction, and glycolide-modified PBAT is obtained.

[0046] The biodegradation percentage of the glycolide-modified PBAT prepared in Example 3 after 60 days of composting was 96%, as shown in Table 1 below.

[0047] Table 1 Performance test data of glycolide modified PBAT material project Biodegradation percentage Example 1 78% Example 2 85% Example 3 96% The change in biodegradation percentage of glycolide-modified PBAT material after 60 days of composting treatment. The larger the biodegradation percentage, the faster the degradation rate of PBAT and the better the degradation performance.

[0048] It should be clear that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. In addition, for the sake of brevity, a detailed description of known methods and technologies is omitted here.

[0049] The above are only embodiments of the present application and are not limited to the present application. For those skilled in the art, the present application may have various changes and variations without departing from the scope of the present invention. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A method for preparing glycolide-modified PBAT, characterized in that: The preparation method comprises the following steps: Adipic acid, 1,4-butanediol, terephthalic acid, glycolide and a catalyst are added into a reaction kettle, nitrogen is introduced for replacement, and then heated to a first preset temperature for a first esterification reaction; Continue to raise the temperature to a second preset temperature to carry out a second esterification reaction; Raising the temperature to a third preset temperature, adding the catalyst and the heat stabilizer, and performing a pre-polycondensation reaction under a first vacuum environment; After the pre-polycondensation reaches the end point, the temperature is raised to a fourth preset temperature and a polycondensation reaction is carried out under a second vacuum environment to obtain a glycolide-modified PBAT material.

2. The method for preparing glycolide-modified PBAT according to claim 1, characterized in that: The molar ratio of the 1,4-butanediol, the adipic acid, the terephthalic acid and the glycolide is 1.2:0.4:0.6:0.

2.

3. The method for preparing glycolide-modified PBAT according to claim 1, characterized in that: The first preset temperature is 150-180°C.

4. The method for preparing glycolide-modified PBAT according to claim 1, characterized in that: The second preset temperature is 180-200°C.

5. The method for preparing glycolide-modified PBAT according to claim 1, characterized in that: The third preset temperature is 200-240°C.

6. The method for preparing glycolide-modified PBAT according to claim 1, characterized in that: The fourth preset temperature is 245-250°C.

7. The method for preparing glycolide-modified PBAT according to claim 1, characterized in that: The catalyst is a mixture of tetrabutyl titanate and stannous octoate.

8. The method for preparing glycolide-modified PBAT according to claim 7, characterized in that: The added amount of the tetrabutyl titanate is 5‰ of the acid mass, and the acid mass is the total mass of the adipic acid and the terephthalic acid.

9. The method for preparing glycolide-modified PBAT according to claim 7, characterized in that: The added amount of the stannous octoate is 4.5-7.5‰ of the acid mass, and the acid mass is the total mass of the adipic acid and the terephthalic acid.

10. The method for preparing glycolide-modified PBAT according to claim 1, characterized in that: In the pre-polycondensation reaction, the mass ratio of the heat stabilizer to the catalyst is (0.5-1.0):1.0.

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