A PEF copolyester with high UV shielding ability and preparation method thereof

Abstract

The invention discloses a polyethersulfurylene oxide (PEF) copolyester with high ultraviolet shielding ability and a preparation method thereof. The PEF copolyester is a linear copolyester of ethylene 2,5-furandicarboxylate and 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl 2,5-furandicarboxylate. The PEF copolyester is obtained by condensation polymerization using 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol, ethylene glycol and dimethyl 2,5-furandicarboxylate as raw materials. 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol is obtained by acetalization reaction with trimethylolpropane. Since 5-hydroxymethylfurfural and the main furan structure have good ultraviolet absorption ability, 5-hydroxymethylfurfural is introduced into the PEF polyester to improve the ultraviolet shielding ability within the range of 200 to 400 nm.

Description

Technical Field

[0001] The present invention relates to the field of polymer materials, and in particular to a bio-based polyester containing an acetal structure and a preparation method thereof. Background Art

[0002] Poly(ethylene 2,5-furandicarboxylate) (PEF) is a bio-based polymer whose raw materials can be derived from biomass feedstocks, such as the monomers 2,5-furandicarboxylic acid (FDCA) and ethylene glycol (EG) obtained from biomass. Compared to the petroleum-based polyester polyethylene terephthalate (PET), PEF polyester has superior mechanical properties and higher gas barrier properties, and can be used in high-barrier packaging materials, high-performance fibers, and engineering plastics. However, PEF can only absorb ultraviolet light in the range of 200 to 300 nm, and its UV shielding performance needs to be further improved to expand its application range.

[0003] Conventionally, various methods can be used to improve the UV shielding properties of PEF, including: 1) physical modification, which involves blending or compounding PEF with modifiers such as inorganic fillers, other resins, or various additives; and 2) chemical modification, which involves altering the molecular structure of PEF through methods such as copolymerization, grafting, segmentation, and crosslinking. However, these methods present numerous challenges, including the high cost of new raw materials, complex modification procedures, cumbersome operations, and the fact that the raw materials are still derived from non-renewable petrochemical byproducts. Summary of the Invention

[0004] In view of this, the present invention provides a PEF copolyester with high UV shielding ability and a preparation method thereof, which solves the problems of various existing methods for improving the UV shielding performance of PEF, such as high cost and complicated modification steps.

[0005] In a first aspect, the PEF copolyester having high UV shielding capability is a linear copolyester containing repeating units of ethylene 2,5-furandicarboxylate and 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl 2,5-furandicarboxylate;

[0006] The number average molecular weight of the PEF copolyester is not less than 10,000 g / mol.

[0007] In the present disclosure and possible embodiments, based on the total molar sum of all repeating units being 100%, the 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl 2,5-furandicarboxylate repeating unit accounts for 5% to 50%; the remainder is the ethylene 2,5-furandicarboxylate repeating unit.

[0008] In the present disclosure and possible embodiments, the repeating unit of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl 2,5-furandicarboxylate accounts for 20% to 50%.

[0009] In a second aspect, the preparation method of the PEF copolyester is to obtain it by bulk polymerization of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol, dimethyl 2,5-furandicarboxylate and ethylene glycol.

[0010] In the present disclosure and possible embodiments, the bulk polymerization method includes:

[0011] The 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol, dimethyl 2,5-furandicarboxylate and ethylene glycol are put into a closed reactor, a catalyst is added, and the mixed system undergoes ester exchange reaction, pre-condensation reaction and polycondensation reaction in the reactor in sequence to obtain the PEF copolyester.

[0012] In the present disclosure and possible embodiments, the ratio of the molar amount of dimethyl 2,5-furandicarboxylate to the sum of the molar amounts of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol and ethylene glycol is 1:1.2-3.

[0013] In the present disclosure and possible embodiments, the ratio of the molar amount of dimethyl 2,5-furandicarboxylate to the sum of the molar amounts of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol and ethylene glycol is 1:1.5; and / or,

[0014] The catalyst is dibutyltin oxide, and the added amount thereof is 0.05% to 0.55% of the sum of the molar amounts of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol and ethylene glycol.

[0015] In the present disclosure and possible embodiments, the catalyst is added in an amount of 0.1% to 0.3% of the sum of the molar amounts of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol and ethylene glycol; and / or,

[0016] The transesterification reaction is carried out under nitrogen protection, with a reaction temperature of 180-220° C. and a reaction time of 5-10 hours.

[0017] In the present disclosure and possible embodiments, the transesterification reaction temperature is 220° C.; and / or,

[0018] The vacuum degree of the pre-polycondensation reaction is 5kPa-20kPa, the reaction temperature is 200-240°C, and the reaction time is 0.5-1h.

[0019] In the present disclosure and possible embodiments, the vacuum degree of the pre-polycondensation reaction is 12 kPa; and / or,

[0020] The polycondensation reaction is carried out under a vacuum degree of less than or equal to 60 Pa, the polycondensation reaction temperature is 240° C., and the polycondensation reaction time is 2 to 5 hours.

[0021] In the present disclosure and possible embodiments, the method for preparing 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol comprises:

[0022] 5-Hydroxymethylfurfural and trimethylolpropane are dissolved in a solvent, and under acidic conditions and stirring, the 5-Hydroxymethylfurfural and the trimethylolpropane undergo an acetalization reaction, and the reaction product is post-treated to obtain the 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol.

[0023] In the present disclosure and possible embodiments, the molar ratio of the 5-hydroxymethylfurfural to the trimethylolpropane is 1:1.05-1.50; and / or,

[0024] The solvent is isopropyl alcohol; and / or,

[0025] The acetalization reaction temperature is 20-35° C., and the reaction time is 12-24 hours; and / or,

[0026] generating the acidic conditions by p-toluenesulfonic acid; and / or,

[0027] The post-processing method comprises:

[0028] After the acetalization reaction is completed, the solvent in the reaction product is removed by evaporation.

[0029] The present invention has the following beneficial effects:

[0030] The PEF copolyester disclosed herein uses a novel bio-based monomer, 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol, for copolymerization. This novel bio-based monomer is synthesized based on 5-hydroxymethylfurfural, a green, renewable resource with a wide range of sources. The PEF copolyester synthesized using 5-hydroxymethylfurfural as a raw material can reduce dependence on petrochemical resources. In addition, because the main furan structure of 5-hydroxymethylfurfural has good ultraviolet absorption capacity, its introduction into the PEF polyester can significantly improve its ultraviolet shielding ability within the range of 200 to 400 nm, thereby enhancing the performance of pure PEF. Therefore, it has the potential to be applied in fields requiring ultraviolet shielding, broadening the scope of use of PEF. Furthermore, the method for preparing the PEF copolyester of the present invention has mild reaction conditions, a simple and easy-to-operate synthesis process, is environmentally friendly, and has a high synthesis yield, providing technical feasibility for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0032] Figure 1 The PTF of Example 2 20 EF 80 UV transmittance curve of copolyester;

[0033] Figure 2 The PTF of Example 3 50 EF 50 UV transmittance curve of copolyester. DETAILED DESCRIPTION

[0034] The present disclosure is described below based on embodiments, but it is worth noting that the present disclosure is not limited to these embodiments. In the detailed description of the present disclosure below, some specific details are described in detail. However, for the parts not described in detail, those skilled in the art can also fully understand the present disclosure.

[0035] In the present disclosure, the PEF copolyester with high UV shielding ability comprises a repeating unit of ethylene 2,5-furandicarboxylate represented by formula (a) and a repeating unit of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl 2,5-furandicarboxylate represented by formula (b); the name is poly(ethylene 2,5-furandicarboxylate-co-5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl 2,5-furandicarboxylate), and the number average molecular weight of this PEF copolyester is not less than 10,000 g / mol;

[0036]

[0037] In the PEF copolyester, based on the molar sum of all repeating units as 100%, the 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl 2,5-furandicarboxylate repeating unit preferably accounts for 5%-50%, more preferably 20%-50%; the rest are ethylene 2,5-furandicarboxylate repeating structural units.

[0038] The poly (ethylene 2,5-furandicarboxylate-co-5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl ester) of the present disclosure can be referred to as PTF. x EF y , wherein T, F and E represent 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol, dimethyl 2,5-furandicarboxylate and ethylene glycol, respectively; the value range of x is greater than 5 and less than 50, and the value range of y is greater than 50 and less than 95, which are the molar proportions of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl 2,5-furandicarboxylate units and ethylene 2,5-furandicarboxylate units in the copolyester * 100%.

[0039] In various embodiments of the present disclosure, the method for preparing the PEF copolyester specifically comprises the following steps:

[0040] 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol, dimethyl 2,5-furandicarboxylate, and ethylene glycol are placed in a closed reactor, a catalyst is added, and ester exchange reaction, pre-polycondensation, and final polycondensation reaction are carried out in sequence to obtain the PEF copolyester.

[0041] The preferred molar ratio of the alkyd to the acid is 1.2-3:1, where the molar ratio is the ratio of the sum of the moles of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol and ethylene glycol to the molar amount of dimethyl 2,5-furandicarboxylate. More preferably, the molar ratio is 1.5:1.

[0042] Among them, the catalyst is preferably dibutyltin oxide, and the added amount of the catalyst is 0.05% to 0.55% of the total molar amount of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol and ethylene glycol, and more preferably 0.1% to 0.3%.

[0043] Among them, it is preferred to carry out the transesterification reaction under the protection of nitrogen; the temperature of the transesterification reaction is 180-220°C, and the transesterification reaction time is 5 to 10 hours; more preferably, the temperature of the transesterification reaction is 220°C.

[0044] Among them, preferably, the vacuum degree of the pre-polycondensation reaction is 5kPa-20kPa; the reaction temperature is 200-240°C, and the reaction time is 0.5-1h; more preferably, the vacuum degree of the pre-polycondensation reaction is 12kPa.

[0045] Among them, it is preferred to carry out the final polycondensation reaction under high vacuum, the polycondensation reaction is carried out under a vacuum degree of less than or equal to 60 Pa, the polycondensation reaction temperature is 240° C., and the polycondensation reaction time is 2 to 5 hours.

[0046] In the present disclosure, the structural formula of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol is:

[0047]

[0048] In the present disclosure, the 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol is derived from 5-hydroxymethylfurfural, which is obtained by acetalization of 5-hydroxymethylfurfural and trimethylolpropane; preferably, the molar ratio of 5-hydroxymethylfurfural to trimethylolpropane is 1:1.05-1.50; and the specific steps of its preparation method are:

[0049] 5-Hydroxymethylfurfural and trimethylolpropane are dissolved in a solvent, and an acetalization reaction is carried out between 5-Hydroxymethylfurfural and trimethylolpropane under acidic and stirring conditions. The reaction product is post-treated to obtain the 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol.

[0050] The solvent is isopropanol; the acidic condition can be provided by p-toluenesulfonic acid; the reaction temperature of the acetalization reaction is 20-35° C., and the reaction time is 12-24 hours; and the post-treatment is to evaporate excess solvent in the reaction product after the reaction is completed to obtain a 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol monomer containing an acetal structure.

[0051] In the embodiments of the present disclosure, unless otherwise specified, all raw materials are basically purchased from commercial sources or prepared by conventional methods in the art.

[0052] In the embodiment of the present disclosure, the ultraviolet transmittance test is performed using a UV-8000 ultraviolet-visible spectrophotometer produced by Shanghai Yuanxi Instrument Co., Ltd., and a full wavelength scanning test is performed within the range of 200 to 800 nm.

[0053] Example 1

[0054] 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol is prepared from 5-hydroxymethylfurfural and trimethylolpropane. The specific process is as follows:

[0055] 10.09 g of 5-hydroxymethylfurfural (0.080 mol), 12.88 g of trimethylolpropane (0.096 mol), and 0.34 g of p-toluenesulfonic acid (0.18 mmol) were weighed and dissolved in 50 mL of isopropanol solution. The mixture was then stirred at 25° C. for 15 h to allow the mixture to undergo an acetalization reaction. After the reaction was completed, the reaction product was evaporated until all the isopropanol solvent was evaporated to obtain the 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol monomer of Example 1 as a yellow powder.

[0056] Example 2

[0057] 1. PTF 20 EF 80 Preparation of copolyester:

[0058] 1) Preparation of PTF by melt polycondensation of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol, ethylene glycol and dimethyl 2,5-furandicarboxylate 20 EF 80 Copolyester:alkyd molar ratio is 1.5:1;

[0059] 2) According to the designed alcohol-acid molar ratio, 3.63 g of 5-ethyl-2-(5-hydroxymethyl-2-furyl)-1,3-dioxane-5-methanol, 3.72 g of ethylene glycol, and 9.21 g of dimethyl 2,5-furandicarboxylate were weighed and placed in an airtight round-bottom flask. 0.025 g of dibutyltin oxide catalyst was added. Under a nitrogen atmosphere, the transesterification temperature was set at 220°C and the reaction was allowed to proceed for 8 h.

[0060] 3) The temperature was raised to 240°C, the nitrogen protection was removed, and pre-condensation was carried out at this temperature and under a vacuum of 12 kPa for 0.5 h;

[0061] 4) The vacuum degree was adjusted to 60 Pa, the temperature was kept constant at 240 ° C, and the polycondensation reaction was carried out for 2 hours to obtain the PTF 20 EF 80 Copolyester.

[0062] 2. PTF 20 EF 80 Copolyester UV transmittance test:

[0063] 1) Weigh an appropriate amount of PTF 20 EF 80Copolyester was melted at 140°C to prepare the films required for testing;

[0064] 2) Set the wavelength scanning range to 200-800 nm and perform the UV transmittance test at room temperature.

[0065] Figure 1 PTF 20 EF 80 From the UV transmittance curve of copolyester, it can be observed that the copolyester has good UV shielding performance in the range of 200-410nm, and its UV absorption range is wider than the range of 200-300nm that PEF can absorb UV.

[0066] Example 3

[0067] 1. PTF 50 EF 50 Preparation of copolyester:

[0068] 1) Preparation of PTF by melt polycondensation of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol, ethylene glycol and dimethyl 2,5-furandicarboxylate 50 EF 50 Copolyester:alkyd molar ratio is 1.5:1;

[0069] 2) Weigh 9.08 g of 5-ethyl-2-(5-hydroxymethyl-2-furyl)-1,3-dioxane-5-methanol, 2.33 g of ethylene glycol, and 9.21 g of dimethyl 2,5-furandicarboxylate according to the designed alcohol-acid molar ratio and place them in an airtight round-bottom flask. Add 0.025 g of dibutyltin oxide catalyst and incubate at 220°C under a nitrogen atmosphere for 8 h.

[0070] 3) The temperature was raised to 240°C, the nitrogen protection was removed, and pre-condensation was carried out at this temperature and under a vacuum of 12 kPa for 0.5 h;

[0071] 4) The vacuum degree was adjusted to 60 Pa, the temperature was kept constant at 240 ° C, and the polycondensation reaction was carried out for 4 hours to obtain the PTF 50 EF 50 Copolyester.

[0072] 2. PTF 50 EF 50 Copolyester UV transmittance test:

[0073] 1) Weigh an appropriate amount of PTF 50 EF 50 Copolyester was melted at 140°C to prepare the films required for testing;

[0074] 2) Set the wavelength scanning range to 200-800 nm and perform the UV transmittance test at room temperature.

[0075] Figure 2 PTF 50 EF 50 From the UV transmittance curve of copolyester, it can be observed that the copolyester has good UV shielding performance in the range of 200-416nm, and its UV absorption range is wider than the range of 200-300nm that PEF can absorb UV.

[0076] The above-described embodiments are merely examples of implementation methods of the present disclosure, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art may make various modifications, equivalent substitutions, and improvements without departing from the scope of the present disclosure, and these modifications are all within the scope of protection of the present disclosure. Therefore, the scope of protection of the present invention shall be based on the appended claims.

Claims

1. A PEF copolyester with high UV shielding ability, characterized in that: The PEF copolyester is a linear copolyester containing repeating units of ethylene 2,5-furandicarboxylate and repeating units of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl 2,5-furandicarboxylate; The number average molecular weight of the PEF copolyester is not less than 10,000 g / mol.

2. The PEF copolyester with high UV shielding ability according to claim 1, characterized in that: Taking the sum of the moles of each repeating unit as 100%, the 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl 2,5-furandicarboxylate repeating unit accounts for 5% to 50%; the rest is the ethylene 2,5-furandicarboxylate repeating unit.

3. The PEF copolyester with high UV shielding ability according to claim 2, characterized in that: The repeating unit of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl 2,5-furandicarboxylate accounts for 20% to 50%.

4. The method for preparing the PEF copolyester according to any one of claims 1 to 3, characterized in that: The PEF copolyester is obtained by bulk polymerization of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol, dimethyl 2,5-furandicarboxylate and ethylene glycol.

5. The method for preparing PEF copolyester according to claim 4, characterized in that: The bulk polymerization method comprises: The 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol, dimethyl 2,5-furandicarboxylate and ethylene glycol are put into a closed reactor, a catalyst is added, and the mixed system undergoes ester exchange reaction, pre-condensation reaction and polycondensation reaction in the reactor in sequence to obtain the PEF copolyester.

6. The method for preparing PEF copolyester according to claim 5, characterized in that: The ratio of the molar amount of the dimethyl 2,5-furandicarboxylate to the sum of the molar amounts of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol and ethylene glycol is 1:1.2-3.

7. The method for preparing PEF copolyester according to claim 6, characterized in that: The ratio of the molar amount of dimethyl 2,5-furandicarboxylate to the sum of the molar amounts of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol and ethylene glycol is 1:1.5; and / or, The catalyst is dibutyltin oxide, and the added amount thereof is 0.05% to 0.55% of the sum of the molar amounts of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol and ethylene glycol.

8. The method for preparing PEF copolyester according to claim 7, characterized in that: The amount of the catalyst added is 0.1% to 0.3% of the sum of the molar amounts of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol and ethylene glycol; and / or, The transesterification reaction is carried out under nitrogen protection, with a reaction temperature of 180-220° C. and a reaction time of 5-10 hours.

9. The method for preparing PEF copolyester according to claim 8, characterized in that: The transesterification reaction temperature is 220°C; and / or, The vacuum degree of the pre-polycondensation reaction is 5kPa-20kPa, the reaction temperature is 200-240°C, and the reaction time is 0.5-1h.

10. The preparation method according to claim 5, characterized in that: The vacuum degree of the pre-polycondensation reaction is 12 kPa; and / or, The polycondensation reaction is carried out under a vacuum degree of less than or equal to 60 Pa, the polycondensation reaction temperature is 240° C., and the polycondensation reaction time is 2 to 5 hours.

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