Isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester and preparation method thereof

Abstract

The invention discloses an isosorbide-based heat-resistant yellowing-resistant biodegradable polyester and a preparation method thereof.The preparation method comprises the following steps that under the condition of an esterification catalyst, dibasic acid and dihydric alcohol are subjected to an esterification reaction, the dibasic acid is composed of terephthalic acid and 1, 1-cyclohexanedicarboxylic acid, and the dihydric alcohol is composed of 1, 1-cyclohexanedicarboxylic acid; the dihydric alcohol is composed of isosorbide and aliphatic dihydric alcohol; after the esterification reaction is finished, adding a polycondensation catalyst, a stabilizer and a toner into an esterification reaction product to carry out polycondensation reaction; after the polycondensation reaction is finished, the polycondensation product is subjected to bracing and grain-sized dicing, and the isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester is obtained. 1, 1-cyclohexanedicarboxylic acid is introduced to replace part of terephthalic acid, aromatic ring structures on polyester chains are reduced, the yellowing resistance of polyester is improved, meanwhile, biomass-sourced isosorbide is added as a heat-resistant modified component, and the isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester is obtained through a direct esterification method.

Description

Technical Field

[0001] The invention relates to the technical field of biodegradable polyesters, and in particular to an isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester and a preparation method thereof. Background Art

[0002] With the increasing depletion of petroleum resources, the deteriorating atmospheric environment, the growing demand for plastics, and the increasing focus on recycling and reuse, the production of new sustainable materials to replace petroleum-based plastics has become a significant challenge and opportunity. Isosorbide is a new, green, non-toxic, and commercially available sugar derivative and the only sugar diol commercially produced on a large scale. Isosorbide is prepared by dehydration of sorbitol, which can be mass-produced through the catalytic hydrogenation of glucose. Due to its advantages such as widespread availability of raw materials, low cost, rigidity, non-toxicity, biodegradability, and outstanding environmental performance, it has been frequently used in recent years as a heat-resistant component to prepare or modify polymer materials.

[0003] Aromatic polyesters contain aromatic ring structures in their molecular chains and typically possess high melting points, mechanical strength, and heat resistance, making them widely used in various fields. However, the aromatic rings in aromatic polyesters readily absorb ultraviolet light, causing changes in the polyester's molecular structure and the generation of a large number of chromophores, which can cause yellowing and aging of the finished product. Furthermore, aromatic polyesters are prone to decomposition at high temperatures, releasing free radicals that further accelerate oxidation reactions, leading to yellowing. Improving the yellowing resistance of polyesters while ensuring high heat resistance is key to preparing high-performance copolyesters. Summary of the Invention

[0004] The purpose of the present invention is to provide an isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester and a preparation method thereof. The present invention introduces 1,1-cyclohexanedicarboxylic acid to replace part of terephthalic acid, thereby reducing the aromatic ring structure on the polyester chain and improving the yellowing resistance of the polyester. At the same time, biomass-derived isosorbide is added as a heat-resistant modification component, and the isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester is obtained by a direct esterification method.

[0005] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0006] The first aspect of the present invention provides a method for preparing an isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester, the preparation method comprising the following steps:

[0007] (a) subjecting a dibasic acid and a diol to an esterification reaction in the presence of an esterification catalyst, wherein the dibasic acid comprises terephthalic acid and 1,1-cyclohexanedicarboxylic acid, and the diol comprises isosorbide and an aliphatic diol;

[0008] (b) after the esterification reaction is completed, adding a polycondensation catalyst, a stabilizer and a toner to the esterification reaction product to carry out a polycondensation reaction;

[0009] (c) After the polycondensation reaction is completed, the polycondensation product is subjected to strip drawing and pelletizing to obtain the isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester.

[0010] Preferably, in step (a), the aliphatic diol is at least one selected from ethylene glycol, 1,4-cyclohexanedimethanol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol and 1,8-octanediol.

[0011] Preferably, in step (a), the esterification catalyst is selected from at least one of zinc acetate, cobalt acetate, aluminum acetate, magnesium acetate, copper acetate and manganese acetate;

[0012] The central metal atom of the esterification catalyst accounts for 10 to 400 ppm of the isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester.

[0013] Preferably, in step (a), the molar ratio of diol to dibasic acid is (1-2):1.

[0014] Preferably, in step (a), the esterification reaction conditions are as follows: reaction temperature is 220° C. to 250° C., stirring rate is 50 to 200 rpm, reaction time is 3 to 4 h, and reaction pressure is 0 to 0.5 MPa.

[0015] Preferably, in step (b), the polycondensation catalyst is selected from at least one of titanium dioxide, tetraethyl titanate, tetraisopropyl titanate and n-butyl titanate;

[0016] The central metal atom of the polycondensation catalyst accounts for 10 to 300 ppm of the isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester.

[0017] Preferably, in step (b), the stabilizer is composed of a heat stabilizer and an antioxidant; the amount of the stabilizer added is 10 to 30 ppm of the isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester;

[0018] The mass ratio of heat stabilizer to antioxidant is 1:(1-9);

[0019] The heat stabilizer is selected from at least one of trimethyl phosphate, triethyl phosphate, triphenyl phosphite and tris(2,4-di-tert-butylphenyl) phosphite;

[0020] The antioxidant is at least one selected from 2,6-dimethylphenol, 2,6-di-tert-butylphenol, 2-tert-butyl-6-methylphenol, N-phenyl-α-naphthylamine and N,N'-diphenyl-p-phenylenediamine.

[0021] Preferably, in step (b), the toner is a redness agent and / or a blueness agent;

[0022] The amount of the toner added is 4 to 8 ppm of the isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester.

[0023] Preferably, in step (b), the polycondensation reaction conditions are as follows: reaction temperature is 270-300° C., stirring rate is 50-200 rpm, reaction time is 2-3 h, and reaction pressure is 0.1-100 Pa.

[0024] The second aspect of the present invention provides an isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester prepared by the above-mentioned preparation method.

[0025] Compared with the prior art, the beneficial effects of the present invention include at least:

[0026] The invention introduces 1,1-cyclohexanedicarboxylic acid to replace part of terephthalic acid, thereby reducing the aromatic ring structure on the polyester chain and improving the yellowing resistance of the polyester. At the same time, biomass-derived isosorbide is added as a heat-resistant modification component to obtain isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester through a direct esterification method. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly describes the drawings required for the specific embodiments or the description of the prior art. Similar elements or parts are generally identified by similar reference numerals throughout the drawings. Elements or parts in the drawings are not necessarily drawn to scale.

[0028] Figure 1 This is the H NMR spectrum of the product prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0029] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention and are therefore only used as examples and cannot be used to limit the scope of protection of the present invention.

[0030] It should be noted that, unless otherwise specified, the technical or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0031] Example 1

[0032] This embodiment is a method for preparing an isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester, which comprises the following steps:

[0033] (1) 25.8 g of 1,1-cyclohexanedicarboxylic acid, 224.3 g of terephthalic acid, 182.8 g of 1,4-cyclohexanedimethanol, 36.3 g of ethylene glycol, 14.2 g of isosorbide, and an esterification catalyst were added to a reactor. The esterification catalyst was zinc acetate, and the amount used was 40 ppm based on the weight of the final polyester product calculated as the central metal atom zinc. After nitrogen substitution, the temperature was raised to 235° C. and the timing was started. The pressure was controlled at 0.25-0.3 MPa and the stirring rate was 80 rpm. After 4 hours of esterification reaction, a prepolymer was generated.

[0034] (2) After the esterification is completed, the polycondensation catalyst, redness agent, blueness agent and stabilizer are added to the kettle body. The polycondensation catalyst is n-butyl titanate, and the amount used is 25ppm of the weight of the final polyester calculated based on the central metal atom titanium, the amount of redness agent added is 1ppm of the weight of the final polyester, the amount of blueness agent added is 5ppm of the weight of the final polyester, and the total amount of stabilizer added is 20ppm of the weight of the finished polyester (thermal stabilizer accounts for 7ppm, antioxidant accounts for 13ppm); vacuum polycondensation is carried out, and the vacuuming process is divided into two stages: low vacuum and high vacuum; in the low vacuum stage, the vacuum degree is controlled at more than 200Pa, the temperature in the kettle is controlled at 270℃, the stirring rate is 80rpm, and the duration is 30min; then enter the high vacuum stage, the vacuum degree is controlled within 50Pa, the temperature in the kettle is controlled at 280℃, the stirring rate is 80rpm, and the material is discharged after the polycondensation reaction for 2h;

[0035] (3) The polycondensation product is drawn into strips through a die, cooled in a water tank, and then passed through a pelletizer to obtain the isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester.

[0036] The prepared materials were analyzed by nuclear magnetic hydrogen spectrum, and the analysis results were as follows: Figure 1 As shown by Figure 1 The target product can be synthesized.

[0037] Example 2

[0038] This embodiment is a method for preparing an isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester, which comprises the following steps:

[0039] (1) 25.8 g of 1,1-cyclohexanedicarboxylic acid, 224.3 g of terephthalic acid, 168.7 g of 1,4-cyclohexanedimethanol, 36.3 g of ethylene glycol, 28.5 g of isosorbide, and an esterification catalyst were added to a reaction kettle. The esterification catalyst was zinc acetate, and the amount used was 40 ppm by weight of the final polyester product, calculated as the central metal atom zinc. After nitrogen substitution, the temperature was raised to 235°C and timing was started. The pressure was controlled at 0.25-0.3 MPa and the stirring rate was 80 rpm. After 4 hours of esterification reaction, a prepolymer was produced.

[0040] (2) After the esterification is completed, the polycondensation catalyst, redness agent, blueness agent and stabilizer are added to the kettle body. The polycondensation catalyst is n-butyl titanate, and the amount used is 25ppm of the weight of the final polyester calculated based on the central metal atom titanium, the amount of redness agent added is 1ppm of the weight of the final polyester, the amount of blueness agent added is 5ppm of the weight of the final polyester, and the total amount of stabilizer added is 20ppm of the weight of the finished polyester (thermal stabilizer accounts for 7ppm, antioxidant accounts for 13ppm); vacuum polycondensation is carried out, and the vacuuming process is divided into two stages: low vacuum and high vacuum; in the low vacuum stage, the vacuum degree is controlled at more than 200Pa, the temperature in the kettle is controlled at 270℃, the stirring rate is 80rpm, and the duration is 30min; then enter the high vacuum stage, the vacuum degree is controlled within 50Pa, the temperature in the kettle is controlled at 280℃, the stirring rate is 80rpm, and the material is discharged after the polycondensation reaction for 2h;

[0041] (3) The polycondensation product is drawn into strips through a die, cooled in a water tank, and then passed through a pelletizer to obtain the isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester.

[0042] Example 3

[0043] This embodiment is a method for preparing an isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester, which comprises the following steps:

[0044] (1) 51.7 g of 1,1-cyclohexanedicarboxylic acid, 199.4 g of terephthalic acid, 182.8 g of 1,4-cyclohexanedimethanol, 36.3 g of ethylene glycol, 14.2 g of isosorbide, and an esterification catalyst were added to a reaction kettle. The esterification catalyst was zinc acetate, and the amount used was 40 ppm by weight of the final polyester product, calculated as the central metal atom zinc. After nitrogen substitution, the temperature was raised to 235°C and timing was started. The pressure was controlled at 0.25-0.3 MPa and the stirring rate was 80 rpm. After 4 hours of esterification reaction, a prepolymer was produced.

[0045] (2) After the esterification is completed, the polycondensation catalyst, redness agent, blueness agent and stabilizer are added to the kettle body. The polycondensation catalyst is n-butyl titanate, and the amount used is 25ppm of the weight of the final polyester calculated based on the central metal atom titanium, the amount of redness agent added is 1ppm of the weight of the final polyester, the amount of blueness agent added is 5ppm of the weight of the final polyester, and the total amount of stabilizer added is 20ppm of the weight of the finished polyester (thermal stabilizer accounts for 7ppm, antioxidant accounts for 13ppm); vacuum polycondensation is carried out, and the vacuuming process is divided into two stages: low vacuum and high vacuum; in the low vacuum stage, the vacuum degree is controlled at more than 200Pa, the temperature in the kettle is controlled at 270℃, the stirring rate is 80rpm, and the duration is 30min; then enter the high vacuum stage, the vacuum degree is controlled within 50Pa, the temperature in the kettle is controlled at 280℃, the stirring rate is 80rpm, and the material is discharged after the polycondensation reaction for 2h;

[0046] (3) The polycondensation product is drawn into strips through a die, cooled in a water tank, and then passed through a pelletizer to obtain the isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester.

[0047] Example 4

[0048] This embodiment is a method for preparing an isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester, which comprises the following steps:

[0049] (1) 51.7 g of 1,1-cyclohexanedicarboxylic acid, 199.4 g of terephthalic acid, 168.7 g of 1,4-cyclohexanedimethanol, 36.3 g of ethylene glycol, 28.5 g of isosorbide, and an esterification catalyst were added to a reaction kettle. The esterification catalyst was zinc acetate, and the amount used was 40 ppm by weight of the final polyester product, calculated as the central metal atom zinc. After nitrogen substitution, the temperature was raised to 235°C and timing was started. The pressure was controlled at 0.25-0.3 MPa and the stirring rate was 80 rpm. After 4 hours of esterification reaction, a prepolymer was produced.

[0050] (2) After the esterification is completed, the polycondensation catalyst, redness agent, blueness agent and stabilizer are added to the kettle body. The polycondensation catalyst is n-butyl titanate, and the amount used is 25ppm of the weight of the final polyester calculated based on the central metal atom titanium, the amount of redness agent added is 1ppm of the weight of the final polyester, the amount of blueness agent added is 5ppm of the weight of the final polyester, and the total amount of stabilizer added is 20ppm of the weight of the finished polyester (thermal stabilizer accounts for 7ppm, antioxidant accounts for 13ppm); vacuum polycondensation is carried out, and the vacuuming process is divided into two stages: low vacuum and high vacuum; in the low vacuum stage, the vacuum degree is controlled at more than 200Pa, the temperature in the kettle is controlled at 270℃, the stirring rate is 80rpm, and the duration is 30min; then enter the high vacuum stage, the vacuum degree is controlled within 50Pa, the temperature in the kettle is controlled at 280℃, the stirring rate is 80rpm, and the material is discharged after the polycondensation reaction for 2h;

[0051] (3) The polycondensation product is drawn into strips through a die, cooled in a water tank, and then passed through a pelletizer to obtain the isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester.

[0052] Comparative Example 1

[0053] This comparative example is a method for preparing an isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester, which comprises the following steps:

[0054] (1) 249.2 g of terephthalic acid, 36.3 g of ethylene glycol, 196.8 g of 1,4-cyclohexanedimethanol, and an esterification catalyst were added to a reaction kettle. The esterification catalyst was zinc acetate, and the amount used was 40 ppm by weight of the final polyester product, calculated as the central metal atom zinc. After nitrogen displacement, the temperature was raised to 235°C and timing was started. The pressure was controlled at 0.25-0.3 MPa and the stirring rate was 80 rpm. After 4 hours of esterification reaction, a prepolymer was produced.

[0055] (2) After the esterification is completed, the polycondensation catalyst, redness agent, blueness agent and stabilizer are added to the kettle body. The polycondensation catalyst is n-butyl titanate, and the amount used is 25ppm of the weight of the final polyester calculated based on the central metal atom titanium, the amount of redness agent added is 1ppm of the weight of the final polyester, the amount of blueness agent added is 5ppm of the weight of the final polyester, and the total amount of stabilizer added is 20ppm of the weight of the finished polyester (thermal stabilizer accounts for 7ppm, antioxidant accounts for 13ppm); vacuum polycondensation is carried out, and the vacuuming process is divided into two stages: low vacuum and high vacuum; in the low vacuum stage, the vacuum degree is controlled at more than 200Pa, the temperature in the kettle is controlled at 270℃, the stirring rate is 80rpm, and the duration is 30min; then enter the high vacuum stage, the vacuum degree is controlled within 50Pa, the temperature in the kettle is controlled at 280℃, the stirring rate is 80rpm, and the material is discharged after the polycondensation reaction for 2h;

[0056] (3) The polycondensation product is drawn into strips through a die, cooled in a water tank, and then passed through a pelletizer to obtain the isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester.

[0057] Comparative Example 2

[0058] This comparative example is a method for preparing an isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester, which comprises the following steps:

[0059] (1) 25.8 g of 1,1-cyclohexanedicarboxylic acid, 224.3 g of terephthalic acid, 196.8 g of 1,4-cyclohexanedimethanol, 36.3 g of ethylene glycol, and an esterification catalyst were added to a reaction kettle. The esterification catalyst was zinc acetate, and the amount used was 40 ppm based on the weight of the final polyester product, calculated as the central metal atom zinc. After nitrogen substitution, the temperature was raised to 235°C and timing was started. The pressure was controlled at 0.25-0.3 MPa and the stirring rate was 80 rpm. After 4 hours of esterification reaction, a prepolymer was produced.

[0060] (2) After the esterification is completed, the polycondensation catalyst, redness agent, blueness agent and stabilizer are added to the kettle body. The polycondensation catalyst is n-butyl titanate, and the amount used is 25ppm of the weight of the final polyester calculated based on the central metal atom titanium, the amount of redness agent added is 1ppm of the weight of the final polyester, the amount of blueness agent added is 5ppm of the weight of the final polyester, and the total amount of stabilizer added is 20ppm of the weight of the finished polyester (thermal stabilizer accounts for 7ppm, antioxidant accounts for 13ppm); vacuum polycondensation is carried out, and the vacuuming process is divided into two stages: low vacuum and high vacuum; in the low vacuum stage, the vacuum degree is controlled at more than 200Pa, the temperature in the kettle is controlled at 270℃, the stirring rate is 80rpm, and the duration is 30min; then enter the high vacuum stage, the vacuum degree is controlled within 50Pa, the temperature in the kettle is controlled at 280℃, the stirring rate is 80rpm, and the material is discharged after the polycondensation reaction for 2h;

[0061] (3) The polycondensation product is drawn into strips through a die, cooled in a water tank, and then passed through a pelletizer to obtain the isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester.

[0062] Comparative Example 3

[0063] This comparative example is a method for preparing an isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester, which comprises the following steps:

[0064] (1) 51.7 g of 1,1-cyclohexanedicarboxylic acid, 199.4 g of terephthalic acid, 196.8 g of 1,4-cyclohexanedimethanol, 36.3 g of ethylene glycol, and an esterification catalyst were added to a reaction kettle. The esterification catalyst was zinc acetate, and the amount used was 40 ppm by weight of the final polyester product, calculated as the central metal atom zinc. After nitrogen displacement, the temperature was raised to 235°C and timing was started. The pressure was controlled at 0.25-0.3 MPa and the stirring rate was 80 rpm. After 4 hours of esterification reaction, a prepolymer was produced.

[0065] (2) After the esterification is completed, the polycondensation catalyst, redness agent, blueness agent and stabilizer are added to the kettle body. The polycondensation catalyst is n-butyl titanate, and the amount used is 25ppm of the weight of the final polyester calculated based on the central metal atom titanium, the amount of redness agent added is 1ppm of the weight of the final polyester, the amount of blueness agent added is 5ppm of the weight of the final polyester, and the total amount of stabilizer added is 20ppm of the weight of the finished polyester (thermal stabilizer accounts for 7ppm, antioxidant accounts for 13ppm); vacuum polycondensation is carried out, and the vacuuming process is divided into two stages: low vacuum and high vacuum; in the low vacuum stage, the vacuum degree is controlled at more than 200Pa, the temperature in the kettle is controlled at 270℃, the stirring rate is 80rpm, and the duration is 30min; then enter the high vacuum stage, the vacuum degree is controlled within 50Pa, the temperature in the kettle is controlled at 280℃, the stirring rate is 80rpm, and the material is discharged after the polycondensation reaction for 2h;

[0066] (3) The polycondensation product is drawn into strips through a die, cooled in a water tank, and then passed through a pelletizer to obtain the isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester.

[0067] Experimental example

[0068] The isosorbide-based heat-resistant and yellowing-resistant biodegradable polyesters prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were obtained respectively, and the properties of different isosorbide-based heat-resistant and yellowing-resistant biodegradable polyesters were tested according to the following method;

[0069] Intrinsic viscosity: measured with an Ubbelohde viscometer using phenol / tetrachloroethane (60 / 40 wt / wt) as solvent and a test temperature of 25°C.

[0070] Yellowing Index (YI): The yellowing index (YI) of the prepared polyester was measured according to ASTM D6290, and the sample was tested after heat aging at 140° C. for 72 hours.

[0071] UV aging resistance: Each polyester material sample was irradiated with UV lamp with a wavelength of 350nm at room temperature for 48 hours, with the sample being 10cm away from the UV lamp light source. The UV aging resistance was measured by the retention rate of tensile strength. The larger the value, the better the UV aging resistance.

[0072] Glass transition temperature (Tg): The glass transition temperature of the copolyester was tested by a Q100 differential scanning calorimeter from TA Company of the United States, using nitrogen as the test atmosphere and a heating rate of 10°C / min, from 30°C to 300°C, then cooled to 30°C, and then heated to 300°C.

[0073] Heat Deflection Temperature: Use a heat deflection temperature tester with silicone oil as the test heat transfer medium. Under the environmental conditions of temperature (25±2)°C and relative humidity (50±5)%, increase the temperature at a rate of 120°C / h and adjust the load to 0.45MPa to test the deflection temperature of the prepared polyester.

[0074] The decomposition temperature was measured using a TA (USA) Q-50 thermogravimetric analyzer. Nitrogen was used as the test atmosphere, the sample mass was approximately 10 mg, and the test temperature was raised from room temperature to 600°C at a heating rate of 20°C / min.

[0075] The test results are shown in Table 1:

[0076] Table 1 Test results

[0077]

[0078]

[0079] From Table 1 we can see that:

[0080] Compared with the comparative example, the isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester prepared in the example of the present application has better yellowing resistance and heat resistance.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and description of the present invention.

Claims

1. A method for preparing an isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester, characterized in that: The preparation method comprises the following steps: (a) subjecting a dibasic acid and a diol to an esterification reaction in the presence of an esterification catalyst, wherein the dibasic acid comprises terephthalic acid and 1,1-cyclohexanedicarboxylic acid, and the diol comprises isosorbide and an aliphatic diol; (b) after the esterification reaction is completed, adding a polycondensation catalyst, a stabilizer and a toner to the esterification reaction product to carry out a polycondensation reaction; (c) After the polycondensation reaction is completed, the polycondensation product is subjected to strip drawing and pelletizing to obtain the isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester.

2. The preparation method according to claim 1, characterized in that In the step (a), the aliphatic diol is selected from at least one of ethylene glycol, 1,4-cyclohexanedimethanol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol and 1,8-octanediol.

3. The preparation method according to claim 1, characterized in that In the step (a), the esterification catalyst is selected from at least one of zinc acetate, cobalt acetate, aluminum acetate, magnesium acetate, copper acetate and manganese acetate; The central metal atom of the esterification catalyst accounts for 10 to 400 ppm of the isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester.

4. The preparation method according to claim 1, characterized in that In the step (a), the molar ratio of the diol to the dibasic acid is (1-2):

1.

5. The preparation method according to claim 1, characterized in that In the step (a), the esterification reaction conditions are as follows: reaction temperature is 220° C. to 250° C., stirring rate is 50 to 200 rpm, reaction time is 3 to 4 h, and reaction pressure is 0 to 0.5 MPa.

6. The preparation method according to claim 1, characterized in that In the step (b), the polycondensation catalyst is selected from at least one of titanium dioxide, tetraethyl titanate, tetraisopropyl titanate and n-butyl titanate; The central metal atom of the polycondensation catalyst accounts for 10 to 300 ppm of the isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester.

7. The preparation method according to claim 1, characterized in that In the step (b), the stabilizer is composed of a heat stabilizer and an antioxidant; the amount of the stabilizer added is 10 to 30 ppm of the isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester; The mass ratio of heat stabilizer to antioxidant is 1:(1-9); The heat stabilizer is selected from at least one of trimethyl phosphate, triethyl phosphate, triphenyl phosphite and tris(2,4-di-tert-butylphenyl) phosphite; The antioxidant is at least one selected from 2,6-dimethylphenol, 2,6-di-tert-butylphenol, 2-tert-butyl-6-methylphenol, N-phenyl-α-naphthylamine and N,N'-diphenyl-p-phenylenediamine.

8. The preparation method according to claim 1, characterized in that In the step (b), the toner is a redness agent and / or a blueness agent; The amount of the toner added is 4 to 8 ppm of the isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester.

9. The preparation method according to claim 1, characterized in that In the step (b), the polycondensation reaction conditions are as follows: reaction temperature is 270-300° C., stirring rate is 50-200 rpm, reaction time is 2-3 h, and reaction pressure is 0.1-100 Pa.

10. The isosorbide-based heat-resistant and yellowing-resistant biodegradable polyester prepared by the preparation method according to any one of claims 1 to 9.

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