Composition for synthesizing bio-based polyester, bio-based polyester as well as preparation method and application of bio-based polyester

Abstract

The invention provides a composition for synthesizing bio-based polyester, the bio-based polyester and a preparation method and application of the bio-based polyester, a component (a) comprises first binary acid or ester thereof, and the first binary acid is 3, 6-dimethylpyrazine-2, 5-dipropionic acid; the component (b) comprises a second binary acid, and the second binary acid is aromatic dicarboxylic acid; the component (c) comprises dihydric alcohol, and the dihydric alcohol is aliphatic or alicyclic dihydric alcohol. The bio-based polyester is prepared by adopting the 3, 6-dimethylpyrazine-2, 5-dipropionic acid monomer or the ester thereof obtained from nitrogen-rich biomass, introducing rigid aromatic dicarboxylic acid and adopting a solution polymerization method, so that the problem of thermal degradation of a pyrazine structure can be solved, and meanwhile, the thermal property and the mechanical property of the bio-based polyester can also be improved. The glass transition temperature of the prepared bio-based polyester can reach-20-120 DEG C, the melting point can reach 50-300 DEG C, and after the pyrazine structure is copolymerized with aromatic dicarboxylic acid and dihydric alcohol, the elongation at break is obviously improved, and the toughness is improved.

Description

Technical Field

[0001] The invention belongs to the field of organic synthesis, and specifically relates to a composition for synthesizing bio-based polyester, bio-based polyester, and a preparation method and application thereof. Background Art

[0002] Polyester has the advantages of light weight, easy processing, corrosion resistance, etc., and has been widely used in packaging, transportation, building energy conservation, electronic devices, medical and other fields. However, currently about 99% of polyester materials are produced using non-renewable petrochemical resources, and their large-scale production and application have aggravated the depletion of petrochemical resources. Therefore, the development of bio-based polyester using green and renewable biomass resources has become an important measure to alleviate excessive dependence on petrochemical resources and promote the sustainable development of polyester materials.

[0003] At present, the development and utilization of biomass resources are mainly focused on cellulose materials, while nitrogen-rich biomass resources such as proteins and amino acids have received much less attention. 3,6-Dimethylpyrazine-2,5-dipropionic acid is a bio-based dicarboxylic acid monomer obtained by Dakin-West reaction of glutamic acid. As a new type of bio-based material, the molecular structure of 3,6-dimethylpyrazine-2,5-dipropionic acid contains a pyrazine ring and two propionic acid side chains, which give it good reactivity. However, the pyrazine ring in 3,6-dimethylpyrazine-2,5-dipropionic acid or its ester is prone to thermal degradation during high-temperature polycondensation, making it difficult to obtain high molecular weight polyester. Therefore, the bio-based polyester prepared using it as a raw material has some defects in thermal properties and mechanical properties.

[0004] Therefore, how to modify bio-based polyesters based on 3,6-dimethylpyrazine-2,5-dipropionic acid or its esters to improve their thermal and mechanical properties has become an urgent problem to be solved. Summary of the invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] The first object of the present invention is to provide a composition for synthesizing bio-based polyester, comprising:

[0008] Component (a) includes a first dibasic acid or an ester thereof, wherein the first dibasic acid is 3,6-dimethylpyrazine-2,5-dipropionic acid;

[0009] Component (b), comprising a second dibasic acid, wherein the second dibasic acid is an aromatic dicarboxylic acid;

[0010] Component (c) comprises a diol, wherein the diol is an aliphatic or alicyclic diol.

[0011] Specifically, the aromatic dicarboxylic acid is one or a combination of two or more selected from 2,5-thiophenedicarboxylic acid, 2,4-thiophenedicarboxylic acid, 2,5-furandicarboxylic acid, and 2,4-furandicarboxylic acid; the diol is one or a combination of two or more selected from 1,2-ethanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexanedimethanol, tricyclodecanediol, dicyclopentanediol, 1,5-dimethyldicyclopentanediol, and pentacyclopentadecanediol;

[0012] Preferably, the cyclohexanedimethanol is selected from the group consisting of a cis-trans mixture of 1,4-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, and 1,3-cyclohexanedimethanol, or a combination of two or more thereof;

[0013] More preferably, the cis-trans ratio of the cis-trans mixture of 1,4-cyclohexanedimethanol is 0.25-4.0.

[0014] Specifically, the total feed molar ratio of the component (a) and the component (b) and the feed molar ratio of the component (c) is 1:1, and the feed molar ratio of the component (a) and the component (b) is 1:(0.1-0.5).

[0015] The second object of the present invention is to provide a method for preparing the bio-based polyester as described above, wherein a mixed system comprising a first dibasic acid or its ester, a second dibasic acid, a diol, a catalyst and a solvent is reacted under an inert gas atmosphere to obtain the bio-based polyester.

[0016] Specifically, the catalyst includes any one or a combination of two or more of triethylamine hydrochloride, dibutyltin dilaurate, antimony trioxide, antimony acetate, titanium dioxide, dibutyltin oxide, stannous isooctanoate, monobutyltin triisooctanoate, and germanium dioxide.

[0017] Specifically, the molar ratio of the component (a) and the component (b) to the catalyst is 1000:(0.3-3.0);

[0018] Preferably, the concentration of the component (a) and the component (b) in the solvent is in the range of 0.005-0.1 g / mL.

[0019] Specifically, the solvent includes any one or a combination of two or more of o-dichlorobenzene, toluene, chloroform, cyclohexanone, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, acetone, hexane, and isooctane.

[0020] Specifically, the reaction temperature is 40-150°C, and the reaction time is 8-15h; preferably, the reaction temperature can be 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C or 150°C, etc., and the reaction time can be 8h, 9h, 10h, 11h, 12h, 13h, 14h or 15h, etc., but are not limited to the values ​​listed above, and other values ​​not listed within the above numerical range are also applicable.

[0021] The third object of the present invention is to provide a bio-based polyester prepared by the above-mentioned preparation method, wherein the number average molecular weight of the bio-based polyester is 30000-50000 g·mol -1 , the glass transition temperature is -20-120℃, and the melting point is 50-300℃.

[0022] The fourth object of the present invention is to provide an application of a bio-based polyester, and to apply the bio-based polyester as described above to the fields of polyester film, polyester sheet, multi-layer composite film, and bottle sheet.

[0023] Compared with the prior art, the present invention provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, which have the following beneficial effects:

[0024] The present invention uses 3,6-dimethylpyrazine-2,5-dipropionic acid monomer or its ester obtained from nitrogen-rich biomass, introduces rigid aromatic dicarboxylic acid, and adopts solution polymerization method to prepare bio-based polyester, which can solve the problem of thermal degradation of pyrazine structure, and at the same time can improve the thermal and mechanical properties of bio-based polyester. The glass transition temperature of the bio-based polyester obtained by the present invention can reach -20-120℃, and the melting point can reach 50-300℃. After the copolymerization of pyrazine structure with aromatic dicarboxylic acid and diol, the elongation at break is significantly improved compared with PEF material, and the toughness is improved; it shows application potential in the fields of polyester film, polyester sheet, multilayer composite film, bottle sheet, etc. DETAILED DESCRIPTION

[0025] In order to further explain the technical means and effects adopted by the present invention, the technical solution of the present invention is further described below in conjunction with the preferred embodiments of the present invention, but the present invention is not limited to the scope of the embodiments.

[0026] Example 1

[0027] This embodiment provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0028] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (25.22 g, 0.1 mol), 1,2-ethylene glycol (6.21 g, 0.1 mol), and 280 mL of o-dichlorobenzene were added to the reactor, and then 1.0% of the molar amount of 3,6-dimethylpyrazine-2,5-dipropionic acid catalyst triethylamine hydrochloride was added, and the temperature was gradually raised to 150°C and stirred for 8 hours; the reaction solution was poured into methanol, and polyester precipitated. After filtering, it was washed twice with methanol and dried to obtain poly 3,6-dimethylpyrazine-2,5-dipropionic acid 1,2-ethylene glycol ester. After testing, the number average molecular weight was 41700 g·mol -1 , the glass transition temperature is 24°C, the polyester is completely amorphous and has no melting point; the structural formula is as follows:

[0029]

[0030] Example 2

[0031] This embodiment provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0032] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (22.70 g, 0.09 mol), 2,5-furandicarboxylic acid (1.56 g, 0.01 mol), 1,2-ethylene glycol (6.21 g, 0.1 mol), and 280 mL of o-dichlorobenzene were added to the reactor, and then 3,6-dimethylpyrazine-2,5-dipropionic acid and 2,5-furandicarboxylic acid were added. The catalyst triethylamine hydrochloride with a total molar amount of 1.0% was added, and the temperature was gradually raised to 150°C and stirred for 8 hours; the reaction solution was poured into methanol, and polyester precipitated. After filtering, it was washed twice with methanol and dried to obtain poly 3,6-dimethylpyrazine-2,5-dipropionic acid 2,5-furandicarboxylic acid 1,2-ethylene glycol ester. After testing, the number average molecular weight was 32900 g·mol -1 , the glass transition temperature is 36°C, the melting point is 169°C; the structural formula is as follows:

[0033]

[0034] Example 3

[0035] This embodiment provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0036] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (20.18g, 0.08mol), 2,5-furandicarboxylic acid (4.68g, 0.02mol), 1,2-ethylene glycol (3.12g, 0.1mol), 280mL o-dichlorobenzene were added to the reactor, and then 3,6-dimethylpyrazine-2,5-dipropionic acid and 2,5-furandicarboxylic acid were added. The catalyst triethylamine hydrochloride with a total molar amount of 1.0% was added, and the temperature was gradually raised to 150°C and stirred for 8 hours; the reaction solution was poured into methanol, and polyester precipitated. After filtering, it was washed twice with methanol and dried to obtain poly 3,6-dimethylpyrazine-2,5-dipropionic acid 2,5-furandicarboxylic acid 1,2-ethylene glycol ester. After testing, the number average molecular weight was 37800g·mol -1 , the glass transition temperature is 51°C, the melting point is 178°C; the structural formula is as follows:

[0037]

[0038] Example 4

[0039] This embodiment provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0040] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (17.66 g, 0.07 mol), 2,5-furandicarboxylic acid (4.68 g, 0.03 mol), 1,2-ethylene glycol (6.21 g, 0.1 mol), and 280 mL of o-dichlorobenzene were added to the reactor, and then 3,6-dimethylpyrazine-2,5-dipropionic acid and 2,5-furandicarboxylic acid were added. The catalyst triethylamine hydrochloride with a total molar amount of 1.0% was added, and the temperature was gradually raised to 150° C. and stirred for 8 hours; the reaction solution was poured into methanol, and polyester was formed into a precipitate. After filtering, it was washed twice with methanol and then dried to obtain poly 3,6-dimethylpyrazine-2,5-dipropionic acid 2,5-furandicarboxylic acid 1,2-ethylene glycol ester. After testing, the number average molecular weight was 34900 g·mol -1 , the glass transition temperature is 65℃, the melting point is 183℃; the structural formula is as follows:

[0041]

[0042] Example 5

[0043] This embodiment provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0044] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (17.66 g, 0.07 mol), 2,5-thiophenedicarboxylic acid (4.68 g, 0.03 mol), 1,2-ethylene glycol (6.21 g, 0.1 mol), and 280 mL of o-dichlorobenzene were added to the reactor, and then 3,6-dimethylpyrazine-2,5-dipropionic acid and 2,5-thiophenedicarboxylic acid were added. The catalyst triethylamine hydrochloride with a total molar amount of 1.0% was added, and the temperature was gradually raised to 150° C. and stirred for 8 hours; the reaction solution was poured into methanol, and polyester was precipitated. After filtering, it was washed twice with methanol and then dried to obtain poly 3,6-dimethylpyrazine-2,5-dipropionic acid 2,5-thiophenedicarboxylic acid 1,2-ethylene glycol ester. After testing, the number average molecular weight was 30800 g·mol -1 , the glass transition temperature is 52°C, the melting point is 174°C; the structural formula is as follows:

[0045]

[0046] Example 6

[0047] This embodiment provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0048] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (17.66 g, 0.07 mol), 2,4-furandicarboxylic acid (4.68 g, 0.03 mol), 1,2-ethylene glycol (6.21 g, 0.1 mol), and 280 mL of o-dichlorobenzene were added to the reactor, and then 1.0% of the total molar amount of 3,6-dimethylpyrazine-2,5-dipropionic acid and 2,4-furandicarboxylic acid was added as catalyst triethylamine hydrochloride, and the temperature was gradually raised to 150° C. and stirred for 8 hours; the reaction solution was poured into methanol, and polyester formed a precipitate, which was filtered, washed twice with methanol, and then dried to obtain poly 3,6-dimethylpyrazine-2,5-dipropionic acid 2,4-furandicarboxylic acid 1,2-ethylene glycol ester, and the number average molecular weight was 31100 g·mol -1 , the glass transition temperature is 69°C, the polyester is completely amorphous and has no melting point; the structural formula is as follows:

[0049] Example 7

[0050] This embodiment provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0051] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (17.66 g, 0.07 mol), 2,5-furandicarboxylic acid (1.56 g, 0.01 mol), 2,5-thiophenedicarboxylic acid (3.44 g, 0.02 mol), 1,2-ethylene glycol (6.21 g, 0.1 mol), and 280 mL of o-dichlorobenzene were added to the reactor, and then 3,6-dimethylpyrazine-2,5-dipropionic acid, The catalyst triethylamine hydrochloride containing 1.0% of the total molar amount of 2,5-furandicarboxylic acid and 2,5-thiophenedicarboxylic acid was gradually heated to 150°C and stirred for 8 hours; the reaction solution was poured into methanol, and polyester precipitated. After filtering, it was washed twice with methanol and then dried to obtain poly (3,6-dimethylpyrazine-2,5-dipropionic acid 2,5-furandicarboxylic acid 2,5-thiophenedicarboxylic acid 1,2-ethylene glycol). After testing, the number average molecular weight was 32400 g·mol -1 , the glass transition temperature is 58°C, the melting point is 179°C; the structural formula is as follows:

[0052]

[0053] Example 8

[0054] This embodiment provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0055] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (17.66 g, 0.07 mol), 2,5-furandicarboxylic acid (1.56 g, 0.01 mol), 2,4-furandicarboxylic acid (3.12 g, 0.02 mol), 1,2-ethylene glycol (6.21 g, 0.1 mol), and 280 mL of o-dichlorobenzene were added to the reactor, and then 3,6-dimethylpyrazine-2,5-dipropionic acid, The catalyst triethylamine hydrochloride containing 1.0% of the total molar amount of 2,5-furandicarboxylic acid and 2,4-furandicarboxylic acid was gradually heated to 150°C and stirred for 8 hours; the reaction solution was poured into methanol, and polyester precipitated. After filtering, it was washed twice with methanol and then dried to obtain poly (3,6-dimethylpyrazine-2,5-dipropionic acid 2,5-furandicarboxylic acid 2,4-furandicarboxylic acid 1,2-ethylene glycol). After testing, the number average molecular weight was 35100 g·mol -1 , the glass transition temperature is 66°C, the melting point is 155°C; the structural formula is as follows:

[0056]

[0057] Example 9

[0058] This embodiment provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0059] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (17.66 g, 0.07 mol), 2,5-furandicarboxylic acid (0.78 g, 0.005 mol), 2,4-furandicarboxylic acid (3.90 g, 0.025 mol), 1,2-ethylene glycol (6.21 g, 0.1 mol), and 280 mL of o-dichlorobenzene were added to the reactor, and then 3,6-dimethylpyrazine-2,5-dipropionic acid was added. , 2,5-furandicarboxylic acid and 2,4-furandicarboxylic acid, a total molar amount of 1.0% of the catalyst triethylamine hydrochloride, gradually heated to 150 ° C and continued stirring for 8 hours; the reaction solution was poured into methanol, polyester formed a precipitate, filtered, washed twice with methanol and then dried to obtain poly (3,6-dimethylpyrazine-2,5-dipropionic acid 2,5-furandicarboxylic acid 2,4-furandicarboxylic acid 1,2-ethylene glycol), and the number average molecular weight was 32800 g·mol -1 , the glass transition temperature is 66°C, the melting point is 149°C; the structural formula is as follows:

[0060]

[0061] Example 10

[0062] This embodiment provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0063] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (17.66 g, 0.07 mol), 2,5-furandicarboxylic acid (4.68 g, 0.03 mol), 1,4-cyclohexanedimethanol cis-trans ratio mixture (14.42 g, 0.1 mol, cis-trans ratio of 2), 280 mL of o-dichlorobenzene were added to the reactor, and then 3,6-dimethylpyrazine-2,5-dipropionic acid and 2,5-furandicarboxylic acid were added. The catalyst triethylamine hydrochloride with a total molar amount of 1.0% was added, and the temperature was gradually raised to 150° C. and stirred for 8 hours; the reaction solution was poured into methanol, and polyester was formed into a precipitate. After filtering, it was washed twice with methanol and then dried to obtain poly 3,6-dimethylpyrazine-2,5-dipropionic acid 2,5-furandicarboxylic acid 1,4-cyclohexanedimethanol ester. After testing, the number average molecular weight was 37100 g·mol -1 , the glass transition temperature is 81°C, the melting point is 217°C; the structural formula is as follows:

[0064]

[0065] Embodiment 11

[0066] This embodiment provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0067] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (17.66 g, 0.07 mol), 2,5-furandicarboxylic acid (4.68 g, 0.03 mol), 1,4-butanediol (9.02 g, 0.1 mol), and 280 mL of o-dichlorobenzene were added to the reactor, and then 3,6-dimethylpyrazine-2,5-dipropionic acid and 2,5-furandicarboxylic acid were added. The catalyst triethylamine hydrochloride with a total molar amount of 1.0% was added, and the temperature was gradually raised to 150° C. and stirred for 8 hours; the reaction solution was poured into methanol, and polyester was formed into a precipitate. After filtering, it was washed twice with methanol and then dried to obtain poly 3,6-dimethylpyrazine-2,5-dipropionic acid 2,5-furandicarboxylic acid 1,4-butanediol ester. After testing, the number average molecular weight was 40700 g·mol -1 , the glass transition temperature is 46°C, the melting point is 138°C; the structural formula is as follows:

[0068]

[0069] Example 12

[0070] This embodiment provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0071] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (17.66 g, 0.07 mol), 2,5-furandicarboxylic acid (4.68 g, 0.03 mol), 1,2-ethylene glycol (4.34 g, 0.07 mol), 1,4-butanediol (2.70 g, 0.03 mol), and 280 mL of o-dichlorobenzene were added to the reactor, and then 3,6-dimethylpyrazine-2,5 -dipropionic acid and 2,5-furandicarboxylic acid 1.0% of the total molar amount of catalyst triethylamine hydrochloride, gradually heated to 150 ° C and continued stirring for 8 hours; the reaction solution was poured into methanol, polyester formed precipitate, filtered and washed twice with methanol and then dried to obtain poly 3,6-dimethylpyrazine-2,5-dipropionic acid 2,5-furandicarboxylic acid 1,2-ethylene glycol 1,4-butanediol ester, which was tested and had a number average molecular weight of 41100 g·mol -1 , the glass transition temperature is 49°C, the melting point is 152°C; the structural formula is as follows:

[0072]

[0073] Example 13

[0074] This embodiment provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0075] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (17.66 g, 0.07 mol), 2,5-furandicarboxylic acid (4.68 g, 0.03 mol), 1,4-cyclohexanedimethanol cis-trans mixture (10.09 g, 0.07 mol, cis-trans ratio of 0.3), 1,2-cyclohexanedimethanol (4.33 g, 0.03 mol, cis-trans ratio of 0.3), 280 mL of o-dichlorobenzene were added to the reactor, and then 3, The catalyst triethylamine hydrochloride containing 1.0% of the total molar amount of 6-dimethylpyrazine-2,5-dipropionic acid and 2,5-furandicarboxylic acid is gradually heated to 150°C and stirred for 8 hours; the reaction solution is poured into methanol, and polyester is precipitated. After filtering, it is washed twice with methanol and then dried to obtain poly 3,6-dimethylpyrazine-2,5-dipropionic acid 2,5-furandicarboxylic acid 1,4-cyclohexanedimethanol 1,2-cyclohexanedimethanol ester. After testing, the number average molecular weight is 30600g·mol -1 , the glass transition temperature is 75℃, the melting point is 176℃; the structural formula is as follows:

[0076]

[0077] Embodiment 14

[0078] This embodiment provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0079] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (17.66 g, 0.07 mol), 2,5-furandicarboxylic acid (4.68 g, 0.03 mol), 1,4-cyclohexanedimethanol cis-trans mixture (10.09 g, 0.07 mol, cis-trans ratio of 0.2), 1,2-cyclohexanedimethanol (4.33 g, 0.03 mol, cis-trans ratio of 0.2), 280 mL of o-dichlorobenzene were added to the reactor, and then 3, The catalyst triethylamine hydrochloride containing 1.0% of the total molar amount of 6-dimethylpyrazine-2,5-dipropionic acid and 2,5-furandicarboxylic acid is gradually heated to 150°C and stirred for 8 hours; the reaction solution is poured into methanol, polyester forms a precipitate, filtered, washed twice with methanol and then dried to obtain poly 3,6-dimethylpyrazine-2,5-dipropionic acid 2,5-furandicarboxylic acid 1,4-cyclohexanedimethanol 1,2-cyclohexanedimethanol ester, which is tested to have a number average molecular weight of 31900 g·mol -1 , the glass transition temperature is 79°C, the melting point is 182°C; the structural formula is as follows:

[0080]

[0081] Embodiment 15

[0082] This embodiment provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0083] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (17.66 g, 0.07 mol), 2,5-furandicarboxylic acid (4.68 g, 0.03 mol), 1,4-cyclohexanedimethanol cis-trans mixture (10.09 g, 0.07 mol, cis-trans ratio of 4), 1,2-cyclohexanedimethanol (4.33 g, 0.03 mol, cis-trans ratio of 4), 280 mL of o-dichlorobenzene were added to the reactor, and then 3,6- The catalyst triethylamine hydrochloride containing 1.0% of the total molar amount of dimethylpyrazine-2,5-dipropionic acid and 2,5-furandicarboxylic acid was gradually heated to 150°C and stirred for 8 hours; the reaction solution was poured into methanol, and polyester formed a precipitate, which was filtered, washed twice with methanol and then dried to obtain poly 3,6-dimethylpyrazine-2,5-dipropionic acid 2,5-furandicarboxylic acid 1,4-cyclohexanedimethanol 1,2-cyclohexanedimethanol ester. After testing, the number average molecular weight was 30200 g·mol -1 , the glass transition temperature is 85℃, the melting point is 166℃; the structural formula is as follows:

[0084]

[0085] Example 16

[0086] This embodiment provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0087] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (17.66 g, 0.07 mol), 2,5-furandicarboxylic acid (4.68 g, 0.03 mol), 1,2-ethylene glycol (6.21 g, 0.1 mol), and 280 mL of chloroform were added to the reactor, and then 3,6-dimethylpyrazine-2,5-dipropionic acid and 2,5-furandicarboxylic acid were added. The catalyst antimony trioxide with a total molar amount of 1.0% was added, and the temperature was gradually raised to 40°C and stirred for 14 hours; the reaction solution was poured into methanol, and polyester was precipitated. After filtering, it was washed twice with methanol and then dried to obtain poly 3,6-dimethylpyrazine-2,5-dipropionic acid 2,5-furandicarboxylic acid 1,2-ethylene glycol ester. After testing, the number average molecular weight was 34500 g·mol -1 , the glass transition temperature is 56°C, the melting point is 173°C; the structural formula is as follows:

[0088]

[0089] Embodiment 17

[0090] This embodiment provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0091] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (17.66 g, 0.07 mol), 2,5-furandicarboxylic acid (4.68 g, 0.03 mol), 1,2-ethylene glycol (6.21 g, 0.1 mol), and 280 mL of chloroform were added to the reactor, and then 3,6-dimethylpyrazine-2,5-dipropionic acid and 2,5-furandicarboxylic acid were added. The catalyst antimony trioxide with a total molar amount of 1.0% was added, and the temperature was gradually raised to 40°C and stirred for 14 hours; the reaction solution was poured into methanol, and polyester was precipitated. After filtering, it was washed twice with methanol and then dried to obtain poly 3,6-dimethylpyrazine-2,5-dipropionic acid 2,5-furandicarboxylic acid 1,2-ethylene glycol ester. After testing, the number average molecular weight was 30700 g·mol -1 , the glass transition temperature is 52°C, the melting point is 168°C; the structural formula is as follows:

[0092]

[0093] Embodiment 18

[0094] This embodiment provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0095] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (17.66 g, 0.07 mol), 2,5-furandicarboxylic acid (4.68 g, 0.03 mol), 1,2-ethylene glycol (6.21 g, 0.1 mol), and 280 mL of N,N-dimethylformamide were added to the reactor, and then 1.5% of the total molar amount of 3,6-dimethylpyrazine-2,5-dipropionic acid and 2,5-furandicarboxylic acid was added as a catalyst monobutyl tin triisooctanoate, and the temperature was gradually raised to 120° C. and stirred for 10 hours; the reaction solution was poured into methanol, and polyester formed a precipitate, which was filtered, washed twice with methanol, and then dried to obtain poly 3,6-dimethylpyrazine-2,5-dipropionic acid 2,5-furandicarboxylic acid 1,2-ethylene glycol ester, and the number average molecular weight was 37900 g·mol -1 , the glass transition temperature is 68°C, the melting point is 190°C; the structural formula is as follows:

[0096]

[0097] Embodiment 19

[0098] This embodiment provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0099] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (17.66 g, 0.07 mol), 2,5-furandicarboxylic acid (4.68 g, 0.03 mol), 1,2-ethylene glycol (6.21 g, 0.1 mol), and 280 mL of N,N-dimethylformamide were added to the reactor, and then 3% of the total molar amount of 3,6-dimethylpyrazine-2,5-dipropionic acid and 2,5-furandicarboxylic acid was added. The temperature was gradually raised to 120°C and stirred for 10 hours; the reaction solution was poured into methanol, and polyester formed a precipitate. After filtering, it was washed twice with methanol and then dried to obtain poly 3,6-dimethylpyrazine-2,5-dipropionic acid 2,5-furandicarboxylic acid 1,2-ethylene glycol ester. After testing, the number average molecular weight was 35300 g·mol -1 , the glass transition temperature is 66°C, the melting point is 189°C; the structural formula is as follows:

[0100]

[0101] Embodiment 20

[0102] This embodiment provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0103] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (17.66 g, 0.07 mol), 2,5-furandicarboxylic acid (4.68 g, 0.03 mol), 1,2-ethylene glycol (6.21 g, 0.1 mol), and 280 mL of N,N-dimethylformamide were added to the reactor, and then 0.3% of the total molar amount of 3,6-dimethylpyrazine-2,5-dipropionic acid and 2,5-furandicarboxylic acid was added as a catalyst monobutyl tin triisooctanoate, and the temperature was gradually raised to 120° C. and stirred for 10 hours; the reaction solution was poured into methanol, and polyester formed a precipitate, which was filtered, washed twice with methanol, and then dried to obtain poly 3,6-dimethylpyrazine-2,5-dipropionic acid 2,5-furandicarboxylic acid 1,2-ethylene glycol ester, and the number average molecular weight was 31700 g·mol -1 , the glass transition temperature is 65°C, the melting point is 187°C; the structural formula is as follows:

[0104]

[0105] Comparative Example 1

[0106] This comparative example provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0107] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (25.22 g, 0.1 mol) and 1,2-ethylene glycol (6.21 g, 0.1 mol) were added to the reactor, and then 1.0% molar amount of 3,6-dimethylpyrazine-2,5-dipropionic acid catalyst triethylamine hydrochloride was added, and the temperature was gradually raised to 150°C and stirred for 8 hours. After testing, only the synthetic number average molecular weight was less than 5000 g·mol -1 of low molecular weight polymers.

[0108] Comparative Example 2

[0109] This comparative example provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0110] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (17.66 g, 0.07 mol), 2,5-furandicarboxylic acid (4.68 g, 0.03 mol), and 1,2-ethylene glycol (6.21 g, 0.1 mol) were added to a reactor, and then a catalyst triethylamine hydrochloride with a total molar amount of 1.0% of 3,6-dimethylpyrazine-2,5-dipropionic acid and 2,5-furandicarboxylic acid was added, and the temperature was gradually raised to 150° C. and stirred for 8 hours; after testing, only the synthesized number average molecular weight was less than 5000 g·mol -1 of low molecular weight polymers.

[0111] Comparative Example 3

[0112] This comparative example provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0113] Under nitrogen atmosphere, 2,5-furandicarboxylic acid (15.6 g, 0.1 mol), 1,2-ethylene glycol (6.21 g, 0.1 mol), and 280 mL of o-dichlorobenzene were added to a reactor, and then a catalyst triethylamine hydrochloride with a molar amount of 1.0% of 2,5-furandicarboxylic acid was added, and the temperature was gradually raised to 150° C. and stirred for 8 hours; poly (2,5-furandicarboxylic acid 1,2-ethylene glycol) was obtained, and the number average molecular weight was 22900 g·mol -1 , the glass transition temperature is 76°C and the melting point is 213°C.

[0114] Comparative Example 4

[0115] This comparative example provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0116] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (17.66 g, 0.07 mol), 2,5-furandicarboxylic acid (4.68 g, 0.03 mol), 1,2-ethylene glycol (6.83 g, 0.11 mol), and 280 mL of o-dichlorobenzene were added to the reactor, and then 3,6-dimethylpyrazine-2,5-dipropionic acid and 2,5-furandicarboxylic acid were added. The catalyst triethylamine hydrochloride with a total molar amount of 1.0% was added, and the temperature was gradually raised to 150°C and stirred for 8 hours. After testing, only the number average molecular weight of the synthesized product was less than 5000 g·mol -1 of low molecular weight polymers.

[0117] Comparative Example 5

[0118] This comparative example provides a composition for synthesizing bio-based polyester, bio-based polyester and a preparation method and application thereof, comprising the following steps:

[0119] Under nitrogen atmosphere, 3,6-dimethylpyrazine-2,5-dipropionic acid (17.66 g, 0.07 mol), 2,5-furandicarboxylic acid (4.68 g, 0.03 mol), 1,2-ethylene glycol (6.21 g, 0.1 mol), and 280 mL of o-dichlorobenzene were added to the reactor, and then 1.0% of the total molar amount of 3,6-dimethylpyrazine-2,5-dipropionic acid and 2,5-furandicarboxylic acid was added as catalyst triethylamine hydrochloride, and the temperature was gradually raised to 165° C. and stirred for 18 hours; poly (3,6-dimethylpyrazine-2,5-dipropionic acid 2,5-furandicarboxylic acid 1,2-ethylene glycol ester) was obtained, and the number average molecular weight was 27700 g·mol -1 , the glass transition temperature is 54°C and the melting point is 161°C.

[0120]

[0121]

[0122] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate a composition for synthesizing bio-based polyester, bio-based polyester and its preparation method and application, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0123] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0124] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A composition for synthesizing bio-based polyester, characterized in that: include: Component (a) includes a first dibasic acid or an ester thereof, wherein the first dibasic acid is 3,6-dimethylpyrazine-2,5-dipropionic acid; Component (b), comprising a second dibasic acid, wherein the second dibasic acid is an aromatic dicarboxylic acid; Component (c) comprises a diol, wherein the diol is an aliphatic or alicyclic diol.

2. The composition according to claim 1, characterized in that The aromatic dicarboxylic acid is one or a combination of two or more selected from 2,5-thiophenedicarboxylic acid, 2,4-thiophenedicarboxylic acid, 2,5-furandicarboxylic acid, and 2,4-furandicarboxylic acid; the diol is one or a combination of two or more selected from 1,2-ethylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexanedimethanol, tricyclodecane dimethanol, dicyclopentanediol, 1,5-dimethyldicyclopentanediol, and pentacyclopentadecanediol; Preferably, the cyclohexanedimethanol is selected from the group consisting of a cis-trans mixture of 1,4-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, and 1,3-cyclohexanedimethanol, or a combination of two or more thereof; More preferably, the cis-trans ratio of the cis-trans mixture of 1,4-cyclohexanedimethanol is 0.25-4.

0.

3. The composition according to claim 1, characterized in that The total feed molar ratio of the component (a) and the component (b) and the feed molar ratio of the component (c) is 1:1, and the feed molar ratio of the component (a) and the component (b) is 1:(0.1-0.5).

4. A method for preparing a bio-based polyester as described in any one of claims 1 to 3, characterized in that: Under an inert gas atmosphere, a mixed system comprising a first dibasic acid or an ester thereof, a second dibasic acid, a diol, a catalyst and a solvent is reacted to obtain the bio-based polyester.

5. The preparation method according to claim 4, characterized in that: The catalyst includes any one or a combination of two or more of triethylamine hydrochloride, dibutyltin dilaurate, antimony trioxide, antimony acetate, titanium dioxide, dibutyltin oxide, stannous isooctanoate, monobutyltin triisooctanoate, and germanium dioxide.

6. The preparation method according to claim 4, wherein the molar ratio of the component (a) to the component (b) to the catalyst is 1000:(0.3-3.0); Preferably, the concentration of the component (a) and the component (b) in the solvent is in the range of 0.005-0.1 g / mL.

7. The preparation method according to claim 4, characterized in that: The solvent includes any one of o-dichlorobenzene, toluene, chloroform, cyclohexanone, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, acetone, hexane, and isooctane, or a combination of two or more thereof.

8. The preparation method according to claim 4, wherein the reaction temperature is 40-150°C and the reaction time is 8-15h.

9. A bio-based polyester, characterized in that The bio-based polyester is prepared by the preparation method according to any one of claims 4 to 8, wherein the number average molecular weight of the bio-based polyester is 30,000-50,000 g·mol -1 , the glass transition temperature is -20-120℃, and the melting point is 50-300℃.

10. An application of bio-based polyester, characterized in that: The bio-based polyester described in claim 9 is applied to the fields of polyester films, polyester sheets, multi-layer composite films and bottle sheets.

Images