阅读说明：本技术 一种pbat树脂组合物及其制备方法 (PBAT resin composition and preparation method thereof ) 是由 高梦云 胡江林 王雨龙 方文娟 陈建旭 姜庆梅 刘岩 麻宁 刘振伟 黎源 于 2021-07-09 设计创作，主要内容包括：本发明涉及一种PBAT树脂组合物及其制备方法,主要解决现有技术中PBAT树脂色相较差以及熔体流动性较差的问题。PBAT树脂组合物包含聚对苯二甲酸己二酸丁二醇酯和戊二酸二甲酯。其中,基于PBAT树脂组合物的总重量,戊二酸二甲酯的重量含量为0.05ppm-1000ppm。该PBAT树脂组合物具有优异的光泽度和耐黄变性,同时可以提高PBAT熔体的流动性,改善加工性能。(The invention relates to a PBAT resin composition and a preparation method thereof, and mainly solves the problems of poor color phase of PBAT resin and poor melt flowability in the prior art. The PBAT resin composition comprises polybutylene terephthalate adipate and dimethyl glutarate. Wherein the weight content of dimethyl glutarate is 0.05ppm to 1000ppm, based on the total weight of the PBAT resin composition. The PBAT resin composition has excellent glossiness and yellowing resistance, and can improve the fluidity of PBAT melt and the processing performance.)

1. A PBAT resin composition comprising the components:

i) polybutylene terephthalate adipate;

ii) dimethyl glutarate;

wherein the weight content of dimethyl glutarate is 0.05ppm to 1000ppm, based on the total weight of the PBAT resin composition.

2. The PBAT resin composition of claim 1, in which the dimethyl glutarate is present in an amount of 0.1ppm to 500ppm by weight, based on the total weight of the PBAT composition.

3. The PBAT resin composition of claim 2, in which the dimethyl glutarate is present in an amount of 1ppm to 100ppm by weight, based on the total weight of the PBAT composition.

4. The PBAT resin composition according to claim 1, characterized in that the melt mass flow rate MFR measured at 190 ℃ under 12.5kg is 10g/10min-100g/10 min.

5. The PBAT resin composition according to any of claims 1-4, wherein the weight content of dimethyl glutarate is measured using the following method: accurately weighing 0.2g of PBAT resin composition, adding the PBAT resin composition into a 4ml glass bottle, adding chloroform for dissolution, adding 10mg/Kg of n-hexylbenzene solution after the PBAT resin composition is completely dissolved, testing the peak area of dimethyl glutarate in the prepared solution by GC-MS, and calculating the content of dimethyl glutarate in the PBAT resin composition according to the peak area of dimethyl glutarate in the prepared solution and a dimethyl glutarate standard curve; the standard curve is calibrated with a dimethyl glutarate/n-hexylbenzene solution.

6. The method of preparing a PBAT resin composition according to any of claims 1-5, characterized in that it comprises the steps of: (1) adding adipic acid, terephthalic acid, 1, 4-butanediol, a titanium catalyst and optional dimethyl glutarate into a reaction kettle according to a certain molar ratio, and preferably carrying out normal pressure or slight pressure reduction reaction for 1-2h at the temperature of 180-; the whole reaction process is protected by inert gas all the time; (2) after the esterification reaction is finished, heating and vacuumizing to perform pre-polycondensation reaction; (3) then decompressing the reaction kettle to high vacuum with absolute pressure of 5-100Pa within 30min, carrying out polycondensation reaction, filling inert gas into the reaction kettle to restore the reaction kettle to normal pressure to obtain PBAT melt, extruding the PBAT melt under the protection of the inert gas, cooling the PBAT melt to room temperature, and pelletizing to obtain the PBAT resin composition; optionally, the method also comprises a step (4) of mixing the PBAT resin and dimethyl glutarate in a blender, then putting the mixture into a single-screw extruder, extruding and granulating the mixture at the temperature of 140-240 ℃ preferably to obtain the PBAT resin composition.

7. The process according to claim 6, wherein the temperature of the pre-polycondensation in the step (2) is 230-245 ℃, the pressure is 5-10kPa, and the reaction time is 30-90 min.

8. The process according to claim 6 or 7, wherein in the step (3), the temperature of the polycondensation reaction is 240 ℃ and 260 ℃ and the reaction time is 2 to 4 hours.

9. The method of preparation according to any of claims 6-8, characterized in that dimethyl glutarate is added in step (1) in an amount of 0.05-1000ppm, preferably 1-100ppm, more preferably 5-20ppm, based on the total weight of the PBAT resin composition, and/or dimethyl glutarate is added in step (4) in an amount of 0.05-1000ppm, preferably 1-100ppm, more preferably 5-20ppm, based on the total weight of the PBAT resin composition.

10. The process according to any one of claims 6 to 9, wherein the molar ratio of the amount of 1, 4-butanediol added to the sum of the amounts of adipic acid and terephthalic acid added is from 1.1 to 2.0: 1, and/or the molar ratio of the addition amount of adipic acid to the addition amount of terephthalic acid is 1-9: 9-1, and/or the dosage of the catalyst is 50-150ppm of the total mass of the succinic acid, the terephthalic acid, the 1, 4-butanediol and the catalyst calculated by the mass of the titanium element; preferably, the titanium catalyst used is selected from one or more of titanium dioxide, n-butyl titanate, isopropyl titanate, tetraisopropyl titanate, tetraisobutyl titanate, tetraisooctyl titanate, titanium acetate, titanium lactate, titanium tartrate, titanium citrate, titanium tartrate, titanium glycol, titanium propylene glycol and titanium butylene glycol.

Technical Field

The invention belongs to the field of polymer material synthesis, and particularly relates to a PBAT resin composition with high glossiness, yellowing resistance and good melt fluidity and a preparation method thereof.

Background

The main chain of polybutylene terephthalate adipate (PBAT) is formed by connecting aliphatic structural units and aromatic structural units through ester bonds which are easy to hydrolyze, is easy to be decomposed and metabolized by a plurality of microorganisms or animal and plant in nature, and is finally converted into CO₂And H₂And O. Compared with the traditional biodegradable polyester, the PBAT has higher melting point, good mechanical ductility and processability, can be processed by injection molding, blow molding, film blowing and other forming methods, has extremely wide application, can be applied to the field of packaging, medicine and health, agriculture and the like, and meets the requirements of environmental protection and sustainable development strategy.

Although PBAT has good application value, there are still a series of problems in the current production of PBAT, which limits its large-scale application. For example, in the synthesis of PBAT, poor catalyst selection or reaction sequence defects can result in low gloss and yellow color in the product. Although the molecular weight can be greatly improved by means of chain extension or tackifying, the difficulty of later-stage processing is improved due to the reduction of melt fluidity.

Therefore, a solution is needed to improve the gloss and lubricity of PBAT without affecting other properties of PBAT, and to provide better melt flow during processing.

Disclosure of Invention

The invention aims to provide a PBAT resin composition which has high glossiness and yellowing resistance and also has better melt fluidity during processing.

Another object of the present invention is to provide a method for preparing the PBAT resin composition, which can add dimethyl glutarate during the synthetic process and/or blending process of the PBAT resin, and which is simple and convenient for mass production.

In order to achieve the above purpose, the technical scheme of the invention is as follows:

a PBAT resin composition comprising the following components:

i) polybutylene terephthalate adipate;

ii) dimethyl glutarate;

wherein the weight content of dimethyl glutarate is 0.05ppm to 1000ppm, based on the total weight of the PBAT resin composition.

Through research and a large number of experiments, the invention verifies that the PBAT resin composition prepared by adding a trace amount of dimethyl glutarate has high glossiness and yellowing resistance, has better melt fluidity during processing, and greatly widens the application field of the PBAT resin.

The weight content of the dimethyl glutarate is tested by a GC-MS method, and the testing steps are as follows: accurately weighing 0.2g of PBAT resin composition, adding the PBAT resin composition into a 4ml glass bottle, adding chloroform for dissolution, adding 10mg/Kg of n-hexylbenzene solution after the PBAT resin composition is completely dissolved, testing the peak area of dimethyl glutarate in the prepared solution by GC-MS, and calculating the content of dimethyl glutarate in the PBAT resin composition according to the peak area of dimethyl glutarate in the prepared solution and a dimethyl glutarate standard curve; the standard curve is calibrated with a dimethyl glutarate/n-hexylbenzene solution. The content of dimethyl glutarate is calculated by an internal standard method.

Dimethyl glutarate added into PBAT polyester can play a role similar to a plasticizer and can obviously improve the fluidity of PBAT resin melt. According to the invention, through research, the content of dimethyl glutarate in the PBAT resin composition is controlled to be 0.05ppm-1000ppm, and the glossiness and yellowing resistance of the PBAT resin can be improved. When the content of dimethyl glutarate is too high, the low molecular weight oligomer can affect the mechanical property of the PBAT resin, so that the tensile strength is reduced. When the content of dimethyl glutarate is too low, the plasticizing effect cannot be achieved, and the improvement on the fluidity of the resin is not obvious. Therefore, based on the total weight of the PBAT resin composition, the content of dimethyl glutarate is controlled to be 0.05ppm-1000ppm, so that the PBAT resin composition can be ensured to have better color phase and fluidity, and the mechanical property of the product cannot be reduced due to overhigh content of dimethyl glutarate. The content of dimethyl glutarate is preferably from 0.1ppm to 500ppm, more preferably from 1ppm to 100 ppm.

The melt index of the PBAT resin composition is measured by taking GB/T3682-2000 as a standard, and the melt mass flow rate MFR is 10g/10min-100g/10min under the conditions that the temperature is 190 ℃ and the load is 12.5 kg.

The preparation method of the PBAT resin composition can add dimethyl glutarate in the synthetic process and/or blending process of the PBAT resin, and the weight content of dimethyl glutarate remained in the composition finally is controlled by adjusting the adding amount.

The preparation method of the PBAT resin composition comprises the following steps: (1) adding adipic acid, terephthalic acid, 1, 4-butanediol, a titanium catalyst and optional dimethyl glutarate into a reaction kettle according to a certain molar ratio, and preferably carrying out normal pressure or slight pressure reduction reaction for 1-2h at the temperature of 180-; the whole reaction process is protected by inert gas all the time; (2) after the esterification reaction is finished, heating to the temperature of 230-245 ℃, vacuumizing to the absolute pressure of 5-10kPa, and carrying out the pre-polycondensation reaction for 30-90 min; (3) and (3) decompressing the reaction kettle within 30min to high vacuum with the absolute pressure of 5-100Pa, reacting at the temperature of 240-260 ℃ for 2-4h, stopping stirring, filling inert gas into the reaction kettle to restore the reaction kettle to normal pressure to obtain a PBAT melt, extruding under the protection of the inert gas, cooling to room temperature, and then pelletizing to obtain the PBAT resin. Optionally, the method also comprises a step (4) of blending the PBAT resin and optional dimethyl glutarate in a blender, then putting the mixture into a single-screw extruder, extruding and granulating the mixture at the temperature of 140-240 ℃ to obtain the PBAT resin composition.

According to the preparation method of the PBAT resin composition, the addition amount of dimethyl glutarate in the reaction process is 0.05-1000ppm, preferably 1-100ppm, and more preferably 5-20ppm (based on the total weight of the PBAT resin composition). The mol ratio of the addition amount of the 1, 4-butanediol to the sum of the addition amounts of the adipic acid and the terephthalic acid is 1.1-2.0: 1. the molar ratio of the addition amount of the adipic acid to the addition amount of the terephthalic acid is 1-9: 9-1. Calculated by the mass of the titanium element, the dosage of the catalyst is 50-150ppm of the total mass of the succinic acid, the terephthalic acid, the 1, 4-butanediol and the catalyst. After the reaction is complete, dimethyl glutarate is added during the blending extrusion in an amount of 0.05 to 1000ppm, preferably 1 to 100ppm, more preferably 5 to 20ppm (based on the total weight of the PBAT resin composition). The titanium catalyst is selected from one or more of titanium dioxide, n-butyl titanate, isopropyl titanate, tetraisopropyl titanate, tetraisobutyl titanate, tetraisooctyl titanate, titanium acetate, titanium lactate, titanium tartrate, titanium citrate, titanium tartrate, titanium glycol, titanium propylene glycol and titanium butylene glycol.

The PBAT resin composition can be used for preparing shopping bags, compost bags, mulching films, protective covering films, silo films, film belts, fabrics, non-fabrics, textiles, fishing nets, bearing bags, garbage bags and the like.

Compared with the prior art, the technical scheme of the invention has the following positive effects:

the invention controls the content of dimethyl glutarate in the PBAT resin within the range of 0.05ppm-1000ppm by adding trace dimethyl glutarate in the composition, and the prepared PBAT resin composition has high glossiness and yellowing resistance, has better melt fluidity during processing, and greatly widens the application field of the PBAT resin.

Detailed Description

The present invention is further illustrated by the following examples, which should be construed as limiting the scope of the invention.

Terephthalic acid, adipic acid, 1, 4-butanediol, catalyst tetrabutyl titanate and dimethyl glutarate which are selected by the invention are all from commercial sources.

The apparatus and methods used in the present invention are those commonly used in the art, except where specifically indicated. Wherein the melt index of the PBAT resin composition is measured by a GOTTFERT melt flow index tester, Germany (melt Mass Flow Rate (MFR) is measured at 190 ℃ under 12.5 kg); the Color phase adopts a Color35 model automatic Color difference meter of BYKGardner company to carry out Lab Color difference measurement; the mechanical properties were determined using an Instron 5966 universal tester from Instron corporation (cf. ISO 527 method).

The weight content of dimethyl glutarate is measured by a gas chromatography-mass spectrometer (GC-MS) with a capillary column, and the specific test method is as follows:

(1) the device comprises the following steps:

gas chromatography-quadrupole mass spectrometer-Agilent 7890A-5975C, equipped with mass analysis detectors (Agilent Technologies).

autosampler-G4513A (Agilent Technologies).

GC control station-Agilent Open LAB (Agilent Technologies).

Capillary column-J & W scientific DB-5,30m × 0.32i.d., with 0.25um membrane (Agilent Technologies part number 19091J-413).

Injector-1 ul split-flow-free injector.

(2) And (3) standard curve preparation:

A. preparing trichloromethane: DMF: 50g of a mixed solution of isopropanol 1:1:4 (mass ratio);

B. weighing 0.1 +/-0.01 g of dimethyl glutarate and n-hexylbenzene standard substance into a 20ml glass bottle, and adding 10.0g of the mixed solution obtained in the step A for dissolving to obtain a solution with the standard substance content of about 1%;

C. transferring 0.1 +/-0.01 g of the solution prepared in the step B into a 20ml glass bottle, and adding 9.9g of the mixed solution in the step A for dilution to obtain a solution with the standard substance content of 100 mg/kg;

D. transferring 0.1 +/-0.01 g of the solution prepared in the step C into a 20ml glass bottle, and adding 9.9g of the mixed solution in the step A for dilution to obtain a solution with the standard substance content of 1 mg/kg;

E. the solution prepared in step D and a mixture of chloroform, DMF and isopropanol in a mass ratio of 1:1:4 (as a blank) were removed and filled into 2ml glass vials in the following order: (1) blank; (2)1mg/Kg of standard substance;

F. each glass vial was closed with a septum cap, loaded into an autosampler in the order described above, and the GC-MS analysis procedure was started.

(3) The testing steps are as follows:

A. weighing 0.2g of PBAT resin in a 4ml glass bottle, adding 2.0g of chloroform, and carrying out ultrasonic treatment until the PBAT resin is completely dissolved;

B. weighing 0.1 +/-0.01 g of n-hexylbenzene into a 20ml glass bottle, and adding 10.0g of isopropanol to dissolve;

C. transferring 0.1 +/-0.01 g of the solution prepared in the step B into a 20ml glass bottle, and adding 9.9g of isopropanol for dilution to obtain a solution with the n-hexylbenzene content of 100 mg/Kg;

D. transferring 1 +/-0.01 g of the solution prepared in the step C into a 20ml glass bottle, and adding 9.0g of isopropanol for dilution to obtain a solution with the n-hexylbenzene content of 10 mg/Kg;

E. weighing 0.5g of PBAT solution, adding 0.5g of DMF for dilution, and shaking up;

F. 2.0g of isopropanol solution is added dropwise and continuously shaken in the process, so that the phenomenon of precipitation and agglomeration in the process of sedimentation is avoided;

G. after the sedimentation is completed, centrifugally separating the sediment and the supernatant by using a centrifugal machine, wherein the rotating speed is set to 8000, and the time is 10 min;

H. taking 0.9g of supernatant liquid into a 2ml small bottle, and adding 0.1g of the 10mg/Kg n-hexylbenzene solution prepared in the step D;

I. the 2ml vial was capped tightly and the vial was loaded into the autosampler and the GC-MS analysis procedure was started.

(4) GC operating conditions were as follows:

inlet temperature-200 deg.C

Injection volume-1 ul

Purge gas flow-30 ml/min helium

Column gas flow-1.5-3 ml/min helium

Initial temperature-50 deg.C

Initial time-2-5 min

The heating rate is-15 ℃/min

Termination temperature-300 deg.C

(5) MS operating conditions

Scan mode-SIM mode

Dimethyl glutarate characteristic ion-target ion 59, characteristic ions 100, 129.

N-hexylbenzene characteristic ion-target ion 91, characteristic ions 133, 162.

Scanning time-8 min-15min

Ion source-EI source

Voltage-70 eV

Transmission line temperature-280 deg.C

Ion source temperature-230 deg.C

(6) Computing process

A.1mg/Kg standard substance is subjected to GC-MS analysis to obtain a total ion flow graph (TIC), ions are extracted by respectively using a target ion 59 of dimethyl glutarate and a target ion 91 of n-hexylbenzene, and corresponding ion peak areas obtained by integration are respectively A_{59, mark}And A_{91, mark}Calculating the concentration ratio A1 and the ion peak area ratio B1 of dimethyl glutarate to n-hexylbenzene in the standard substance;

B. performing GC-MS analysis on a test sample to obtain a total ion flow chart (TIC), extracting ions by using a target ion 59 of dimethyl glutarate and a target ion of n-hexylbenzene respectively, and integrating to obtain corresponding ion peak areas A₅₉Sample and A₉₁And (3) calculating the area ratio A of the ion peak areas in the sample results₂And the concentration of n-hexylbenzene C;

C. the content of dimethyl glutarate is calculated by an internal standard method, and the content is A₂×B₁×C/A₁Xdilution factor, in mg/kg.

Examples 1 to 13 and comparative examples 1 to 2:

[ example 1 ]

1000g of terephthalic acid, 1000g of adipic acid, 1700g of 1, 4-butanediol, 0.37g of n-butyl titanate and 0.0016g of dimethyl glutarate are weighed respectively and added into a 5L reaction kettle, stirring is started, nitrogen is replaced for 3 times, and the normal pressure is maintained. Heating the reaction system to 220 ℃ and reacting for 90 min; after the esterification reaction is finished, heating to 240 ℃, vacuumizing to the absolute pressure of 5kPa, and carrying out pre-polycondensation reaction for 60 min; decompressing the reaction kettle to a high vacuum with an absolute pressure of 5Pa within 30min, reacting for 3h at 250 ℃, stopping stirring, filling nitrogen into the reaction kettle to restore the reaction kettle to normal pressure to obtain a PBAT melt, extruding under the protection of nitrogen, cooling to room temperature, and then pelletizing to obtain the PBAT resin composition. The PBAT resin composition had a dimethyl glutarate content of 0.57ppm (based on the total weight of the composition), a melt index of 27.8, a tensile strength of 23.9MPa, L-82.5, b-3.2, YI-1.97 (L value represents gloss, b value represents degree of yellow blue, YI is yellowing index).

[ example 2 ]

1000g of terephthalic acid, 1000g of adipic acid, 1700g of 1, 4-butanediol, 0.37g of n-butyl titanate and 0.0036g of dimethyl glutarate are weighed respectively and added into a 5L reaction kettle, stirring is started, nitrogen is replaced for 3 times, and the normal pressure is maintained. Heating the reaction system to 220 ℃ and reacting for 90 min; after the esterification reaction is finished, heating to 240 ℃, vacuumizing to the absolute pressure of 5kPa, and carrying out pre-polycondensation reaction for 60 min; decompressing the reaction kettle to a high vacuum with an absolute pressure of 5Pa within 30min, reacting for 3h at 250 ℃, stopping stirring, filling nitrogen into the reaction kettle to restore the reaction kettle to normal pressure to obtain a PBAT melt, extruding under the protection of nitrogen, cooling to room temperature, and then pelletizing to obtain the PBAT resin composition. The PBAT resin composition had a dimethyl glutarate content of 1.04ppm (based on the total weight of the composition), a melt index of 30.6, a tensile strength of 23.3MPa, L ═ 83.5, b ═ 3.3, and YI ═ 1.88.

[ example 3 ]

1000g of terephthalic acid, 1000g of adipic acid, 1700g of 1, 4-butanediol, 0.37g of n-butyl titanate and 0.0088g of dimethyl glutarate are respectively weighed and added into a 5L reaction kettle, stirring is started, nitrogen is replaced for 3 times, and the normal pressure is maintained. Heating the reaction system to 220 ℃ and reacting for 90 min; after the esterification reaction is finished, heating to 240 ℃, vacuumizing to the absolute pressure of 5kPa, and carrying out pre-polycondensation reaction for 60 min; decompressing the reaction kettle to a high vacuum with an absolute pressure of 5Pa within 30min, reacting for 3h at 250 ℃, stopping stirring, filling nitrogen into the reaction kettle to restore the reaction kettle to normal pressure to obtain a PBAT melt, extruding under the protection of nitrogen, cooling to room temperature, and then pelletizing to obtain the PBAT resin composition. The PBAT resin composition had a dimethyl glutarate content of 4.02ppm (based on the total weight of the composition), a melt index of 31.1, a tensile strength of 23.0MPa, L ═ 83.4, b ═ 3.0, and YI ═ 1.82.

[ example 4 ]

1000g of terephthalic acid, 1000g of adipic acid, 1700g of 1, 4-butanediol, 0.37g of n-butyl titanate and 0.024g of dimethyl glutarate are weighed respectively and added into a 5L reaction kettle, stirring is started, nitrogen is replaced for 3 times, and the normal pressure is maintained. Heating the reaction system to 220 ℃ and reacting for 90 min; after the esterification reaction is finished, heating to 240 ℃, vacuumizing to the absolute pressure of 5kPa, and carrying out pre-polycondensation reaction for 60 min; decompressing the reaction kettle to a high vacuum with an absolute pressure of 5Pa within 30min, reacting for 3h at 250 ℃, stopping stirring, filling nitrogen into the reaction kettle to restore the reaction kettle to normal pressure to obtain a PBAT melt, extruding under the protection of nitrogen, cooling to room temperature, and then pelletizing to obtain PBAT resin; PBAT resin and 0.003g of dimethyl glutarate were blended in a blender, and then fed into a single-screw extruder, extruded at 200 ℃ and pelletized to obtain a PBAT resin composition. The PBAT resin composition had a dimethyl glutarate content of 10.1ppm (based on the total weight of the composition), a melt index of 35.2, a tensile strength of 22.4MPa, L ═ 83.6, b ═ 2.1, and YI ═ 1.08.

[ example 5 ]

1000g of terephthalic acid, 1000g of adipic acid, 1700g of 1, 4-butanediol, 0.37g of n-butyl titanate and 0.05g of dimethyl glutarate were weighed respectively and added into a 5L reaction kettle, stirring was started, nitrogen gas was replaced 3 times, and the normal pressure was maintained. Heating the reaction system to 220 ℃ and reacting for 90 min; after the esterification reaction is finished, heating to 240 ℃, vacuumizing to the absolute pressure of 5kPa, and carrying out pre-polycondensation reaction for 60 min; decompressing the reaction kettle to a high vacuum with an absolute pressure of 5Pa within 30min, reacting for 3h at 250 ℃, stopping stirring, filling nitrogen into the reaction kettle to restore the reaction kettle to normal pressure to obtain a PBAT melt, extruding under the protection of nitrogen, cooling to room temperature, and then pelletizing to obtain PBAT resin; PBAT resin and 0.005g of dimethyl glutarate were blended in a blender, and then fed into a single-screw extruder, extruded at 200 ℃ and pelletized to obtain a PBAT resin composition. The PBAT resin composition had a dimethyl glutarate content of 20.2ppm (based on the total weight of the composition), a melt index of 38.5, a tensile strength of 21.9MPa, L ═ 83.4, b ═ 2.4, and YI ═ 1.21.

[ example 6 ]

1000g of terephthalic acid, 1000g of adipic acid, 1700g of 1, 4-butanediol, 0.37g of n-butyl titanate and 0.12g of dimethyl glutarate were weighed respectively and added into a 5L reaction kettle, stirring was started, nitrogen gas was replaced 3 times, and the normal pressure was maintained. Heating the reaction system to 220 ℃ and reacting for 90 min; after the esterification reaction is finished, heating to 240 ℃, vacuumizing to the absolute pressure of 5kPa, and carrying out pre-polycondensation reaction for 60 min; decompressing the reaction kettle to a high vacuum with an absolute pressure of 5Pa within 30min, reacting for 3h at 250 ℃, stopping stirring, filling nitrogen into the reaction kettle to restore the reaction kettle to normal pressure to obtain a PBAT melt, extruding under the protection of nitrogen, cooling to room temperature, and then pelletizing to obtain PBAT resin; the PBAT resin and 0.013g of dimethyl glutarate were blended in a blender, and then fed into a single-screw extruder, extruded at 140 ℃ and pelletized to obtain a PBAT resin composition. The PBAT resin composition had a dimethyl glutarate content of 50.4ppm (based on the total weight of the composition), a melt index of 35.2, a tensile strength of 22.4MPa, L ═ 83.6, b ═ 2.6, and YI ═ 1.48.

[ example 7 ]

1000g of terephthalic acid, 1000g of adipic acid, 1700g of 1, 4-butanediol, 0.37g of n-butyl titanate and 0.25g of dimethyl glutarate were weighed respectively and added into a 5L reaction kettle, stirring was started, nitrogen gas was replaced 3 times, and the normal pressure was maintained. Heating the reaction system to 220 ℃ and reacting for 90 min; after the esterification reaction is finished, heating to 240 ℃, vacuumizing to the absolute pressure of 5kPa, and carrying out pre-polycondensation reaction for 60 min; decompressing the reaction kettle to a high vacuum with an absolute pressure of 5Pa within 30min, reacting for 3h at 250 ℃, stopping stirring, filling nitrogen into the reaction kettle to restore the reaction kettle to normal pressure to obtain a PBAT melt, extruding under the protection of nitrogen, cooling to room temperature, and then pelletizing to obtain PBAT resin; the PBAT resin and 0.027g of dimethyl glutarate were blended in a blender, and then fed into a single-screw extruder, extruded at 240 ℃, and pelletized to obtain a PBAT resin composition. The PBAT resin composition had a dimethyl glutarate content of 102.1ppm (based on the total weight of the composition), a melt index of 38.3, a tensile strength of 22.2MPa, L ═ 83.7, b ═ 2.8, and YI ═ 1.58.

[ example 8 ]

1000g of terephthalic acid, 1000g of adipic acid, 1700g of 1, 4-butanediol, 0.37g of n-butyl titanate and 0.50g of dimethyl glutarate were weighed respectively and added into a 5L reaction kettle, stirring was started, nitrogen gas was replaced 3 times, and the normal pressure was maintained. Heating the reaction system to 220 ℃ and reacting for 90 min; after the esterification reaction is finished, heating to 240 ℃, vacuumizing to the absolute pressure of 5kPa, and carrying out pre-polycondensation reaction for 60 min; decompressing the reaction kettle to a high vacuum with an absolute pressure of 5Pa within 30min, reacting for 3h at 250 ℃, stopping stirring, filling nitrogen into the reaction kettle to restore the reaction kettle to normal pressure to obtain a PBAT melt, extruding under the protection of nitrogen, cooling to room temperature, and then pelletizing to obtain PBAT resin; PBAT resin and 0.088g of dimethyl glutarate were blended in a blender, and then fed into a single-screw extruder, extruded at 200 ℃, and pelletized to obtain a PBAT resin composition. The PBAT resin composition had a dimethyl glutarate content of 211.2ppm (based on the total weight of the composition), a melt index of 37.4, a tensile strength of 21.7MPa, L ═ 83.9, b ═ 2.8, and YI ═ 1.53.

[ example 9 ]

1000g of terephthalic acid, 1000g of adipic acid, 1700g of 1, 4-butanediol, 0.37g of n-butyl titanate and 0.67g of dimethyl glutarate were weighed respectively and added to a 5L reaction kettle, and stirring was started, nitrogen substitution was carried out 3 times, and the normal pressure was maintained. Heating the reaction system to 220 ℃ and reacting for 90 min; after the esterification reaction is finished, heating to 240 ℃, vacuumizing to the absolute pressure of 5kPa, and carrying out pre-polycondensation reaction for 60 min; decompressing the reaction kettle to a high vacuum with an absolute pressure of 5Pa within 30min, reacting for 3h at 250 ℃, stopping stirring, filling nitrogen into the reaction kettle to restore the reaction kettle to normal pressure to obtain a PBAT melt, extruding under the protection of nitrogen, cooling to room temperature, and then pelletizing to obtain PBAT resin; the PBAT resin and 0.25g of dimethyl glutarate were blended in a blender, and then fed into a single-screw extruder, extruded at 200 ℃, and pelletized to obtain a PBAT resin composition. The PBAT resin composition had a dimethyl glutarate content of 335.1ppm (based on the total weight of the composition), a melt index of 39.0, a tensile strength of 21.4MPa, L ═ 84.0, b ═ 2.9, and YI ═ 1.62.

[ example 10 ]

1000g of terephthalic acid, 1000g of adipic acid, 1700g of 1, 4-butanediol, 0.37g of n-butyl titanate and 0.09g of dimethyl glutarate were weighed respectively and added to a 5L reaction kettle, and stirring was started, nitrogen substitution was carried out 3 times, and the pressure was maintained at normal pressure. Heating the reaction system to 220 ℃ and reacting for 90 min; after the esterification reaction is finished, heating to 240 ℃, vacuumizing to the absolute pressure of 5kPa, and carrying out pre-polycondensation reaction for 60 min; decompressing the reaction kettle to a high vacuum with an absolute pressure of 5Pa within 30min, reacting for 3h at 250 ℃, stopping stirring, filling nitrogen into the reaction kettle to restore the reaction kettle to normal pressure to obtain a PBAT melt, extruding under the protection of nitrogen, cooling to room temperature, and then pelletizing to obtain PBAT resin; PBAT resin and 1.3g of dimethyl glutarate were blended in a blender, and then fed into a single-screw extruder, extruded at 200 ℃ and pelletized to obtain a PBAT resin composition. The PBAT resin composition had a dimethyl glutarate content of 530.2ppm (based on the total weight of the composition), a melt index of 41.0, a tensile strength of 20.8MPa, L ═ 84.3, b ═ 2.8, and YI ═ 1.53.

[ example 11 ]

1000g of terephthalic acid, 1000g of adipic acid, 1700g of 1, 4-butanediol, 0.37g of n-butyl titanate and 0.50g of dimethyl glutarate were weighed respectively and added into a 5L reaction kettle, stirring was started, nitrogen gas was replaced 3 times, and the normal pressure was maintained. Heating the reaction system to 220 ℃ and reacting for 90 min; after the esterification reaction is finished, heating to 240 ℃, vacuumizing to the absolute pressure of 5kPa, and carrying out pre-polycondensation reaction for 60 min; decompressing the reaction kettle to a high vacuum with an absolute pressure of 5Pa within 30min, reacting for 3h at 250 ℃, stopping stirring, filling nitrogen into the reaction kettle to restore the reaction kettle to normal pressure to obtain a PBAT melt, extruding under the protection of nitrogen, cooling to room temperature, and then pelletizing to obtain PBAT resin; PBAT resin and 1.3g of dimethyl glutarate were blended in a blender, and then fed into a single-screw extruder, extruded at 200 ℃ and pelletized to obtain a PBAT resin composition. The PBAT resin composition had a dimethyl glutarate content of 666.7ppm (based on the total weight of the composition), a melt index of 43.1, a tensile strength of 20.5MPa, L ═ 84.1, b ═ 3.2, and YI ═ 1.92.

[ example 12 ]

1000g of terephthalic acid, 1000g of adipic acid, 1700g of 1, 4-butanediol, 0.37g of n-butyl titanate and 0.21g of dimethyl glutarate were weighed respectively and added into a 5L reaction kettle, stirring was started, nitrogen gas was replaced 3 times, and the normal pressure was maintained. Heating the reaction system to 220 ℃ and reacting for 90 min; after the esterification reaction is finished, heating to 240 ℃, vacuumizing to the absolute pressure of 5kPa, and carrying out pre-polycondensation reaction for 60 min; decompressing the reaction kettle to a high vacuum with an absolute pressure of 5Pa within 30min, reacting for 3h at 250 ℃, stopping stirring, filling nitrogen into the reaction kettle to restore the reaction kettle to normal pressure to obtain a PBAT melt, extruding under the protection of nitrogen, cooling to room temperature, and then pelletizing to obtain PBAT resin; PBAT resin and 2.0g of dimethyl glutarate were blended in a blender, and then fed into a single-screw extruder, extruded at 200 ℃ and pelletized to obtain a PBAT resin composition. The PBAT resin composition had a dimethyl glutarate content of 804.7ppm (based on the total weight of the composition), a melt index of 45.5, a tensile strength of 20.1MPa, L ═ 84.3, b ═ 3.5, and YI ═ 2.12.

[ example 13 ]

1000g of terephthalic acid, 1000g of adipic acid, 1700g of 1, 4-butanediol, 0.37g of n-butyl titanate and 0.015g of dimethyl glutarate are respectively weighed and added into a 5L reaction kettle, stirring is started, nitrogen is replaced for 3 times, and the normal pressure is kept. Heating the reaction system to 220 ℃ and reacting for 90 min; after the esterification reaction is finished, heating to 240 ℃, vacuumizing to the absolute pressure of 5kPa, and carrying out pre-polycondensation reaction for 60 min; decompressing the reaction kettle to a high vacuum with an absolute pressure of 5Pa within 30min, reacting for 3h at 250 ℃, stopping stirring, filling nitrogen into the reaction kettle to restore the reaction kettle to normal pressure to obtain a PBAT melt, extruding under the protection of nitrogen, cooling to room temperature, and then pelletizing to obtain PBAT resin; PBAT resin and 2.6g of dimethyl glutarate were blended in a blender, and then fed into a single-screw extruder, extruded at 200 ℃ and pelletized to obtain a PBAT resin composition. The PBAT resin composition had a dimethyl glutarate content of 955.2ppm (based on the total weight of the composition), a melt index of 48.5, a tensile strength of 19.6MPa, L ═ 84.5, b ═ 3.8, and YI ═ 2.58.

Comparative example 1

1000g of terephthalic acid, 1000g of adipic acid, 1700g of 1, 4-butanediol and 0.37g of n-butyl titanate are weighed respectively, added into a 5L reaction kettle, stirred, replaced by nitrogen for 3 times, and kept at normal pressure. Heating the reaction system to 220 ℃ and reacting for 90 min; after the esterification reaction is finished, heating to 240 ℃, vacuumizing to the absolute pressure of 5kPa, and carrying out pre-polycondensation reaction for 60 min; decompressing the reaction kettle to a high vacuum with an absolute pressure of 5Pa within 30min, reacting for 3h at 250 ℃, stopping stirring, filling nitrogen into the reaction kettle to restore the reaction kettle to normal pressure to obtain a PBAT melt, extruding under the protection of nitrogen, cooling to room temperature, and then pelletizing to obtain the PBAT resin composition; the PBAT resin had a dimethyl glutarate content of 0.025ppm (based on the total weight of the composition), a melt index of 20.6, a tensile strength of 23.8MPa, L ═ 78.8, b ═ 4.0, and YI ═ 2.65.

Comparative example 2

1000g of terephthalic acid, 1000g of adipic acid, 1700g of 1, 4-butanediol, 0.37g of n-butyl titanate and 0.43g of dimethyl glutarate were weighed respectively and added to a 5L reaction kettle, and stirring was started, nitrogen substitution was carried out 3 times, and the normal pressure was maintained. Heating the reaction system to 220 ℃ and reacting for 90 min; after the esterification reaction is finished, heating to 240 ℃, vacuumizing to the absolute pressure of 5kPa, and carrying out pre-polycondensation reaction for 60 min; decompressing the reaction kettle to a high vacuum with an absolute pressure of 5Pa within 30min, reacting for 3h at 250 ℃, stopping stirring, filling nitrogen into the reaction kettle to restore the reaction kettle to normal pressure to obtain a PBAT melt, extruding under the protection of nitrogen, cooling to room temperature, and then pelletizing to obtain PBAT resin; mixing PBAT resin and 3.0g dimethyl glutarate in a blender, putting into a single-screw extruder, extruding at 200 ℃, and granulating to obtain PBAT resin composition; the PBAT resin composition had a dimethyl glutarate content of 1250.2ppm (based on the total weight of the composition), a melt index of 60.1, a tensile strength of 16.8MPa, L-86.2, b-4.2, YI-2.78.

As can be seen from the examples and comparative examples, the compositions have excellent gloss values with L.gtoreq.82 at dimethyl glutarate levels of 0.05ppm to 1000ppm in the PBAT compositions. While comparative example 1, in which the content of dimethyl glutarate was less than 0.05ppm, the L value was only 78.8, indicating that the introduction of dimethyl glutarate can significantly improve the gloss of the composition. Similarly, the addition of dimethyl glutarate also significantly improves the yellowing resistance of the PBAT resin. Besides, when the content of dimethyl glutarate is between 0.05ppm and 1000ppm, the melt flowability can be obviously improved, and the melt index is increased from 20.6 to 48.5. However, if the content of dimethyl glutarate in the composition is higher than 1000ppm, the mechanical property of the PBAT resin is obviously reduced, and the tensile strength is reduced from 23.8MPa to 16.8 MPa.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.