A PBS copolyester with high glass transition temperature and preparation method thereof

Abstract

The invention discloses a PBS copolyester with a high glass transition temperature and a preparation method thereof. The PBS copolyester is a linear copolyester containing butylene succinate repeating units and 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl succinate repeating units. The 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl succinate repeating units are provided by a monomer obtained by acetalization reaction of 5-hydroxymethylfurfural and trimethylolpropane. Since the monomer has a new acetal ring structure, it can be introduced into the PBS polyester to obtain a modified PBS copolyester with a high glass transition temperature. Meanwhile, the preparation method has the characteristics of simple synthesis process, easy operation and high synthesis yield, thereby providing technical feasibility for large-scale production.

Description

Technical Field

[0001] The present invention relates to the field of polymer materials, the utilization of renewable resources and the technical field of green synthesis, and in particular to a PBS copolyester with a high glass transition temperature and a preparation method thereof. Background Art

[0002] Polybutylene succinate (PBS) is a biodegradable aliphatic polyester with numerous advantages, including excellent mechanical properties and good biodegradability. It is one of the most promising environmentally friendly materials to replace traditional polymers, primarily used in packaging, tableware, and biomedical devices. However, its low glass transition temperature of -45°C makes it unsuitable for high-temperature applications.

[0003] Under normal circumstances, a variety of methods can be used to increase the glass transition temperature of PBS: 1) blending modification, such as improving the performance of PBS by adding inorganic fillers, organic small molecule additives or macromolecular modifiers to the PBS melt; 2) copolymerization modification, such as introducing copolymer components such as flexible structure monomers and rigid structure monomers into the PBS main chain to improve the performance of PBS; 3) copolymerization / blending modification, such as copolymerizing PBS and then further melt blending it with unmodified PBS for modification.

[0004] However, the above methods have many problems: for example, the thermal and mechanical properties of the modified PBS material are poor, the cost of new raw materials is high, and the raw materials still come from non-renewable petrochemical by-products. Summary of the Invention

[0005] In view of this, the present invention provides a PBS copolyester with a high glass transition temperature and a preparation method thereof, which solves the problems of various existing methods for increasing the glass transition temperature of PBS, such as high cost and complicated modification steps.

[0006] In a first aspect, the PBS copolyester having a high glass transition temperature is a linear copolyester containing repeating units of butylene succinate and repeating units of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl succinate, and its number average molecular weight 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 succinate repeating units account for 5%-50%, and the remainder are butylene succinate repeating structural units.

[0008] In the present disclosure and possible embodiments, the repeating unit of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl succinate accounts for 30% to 50%.

[0009] In the second aspect, the preparation method of the PBS copolyester described in the first aspect is specifically to obtain it by bulk polymerization of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol, 1,4-butanediol and 1,4-butanediol.

[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, 1,4-butanediol and 1,4-butanediol are put into a closed reactor, a catalyst is added, and the mixed system in the reactor sequentially undergoes an ester exchange reaction, a pre-polycondensation reaction and a polycondensation reaction to obtain the PBS copolyester.

[0012] In the present disclosure and possible embodiments, the ratio of the molar amount of 1,4-butanediol to the sum of the molar amounts of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol and 1,4-butanediol is 1:1.2-3.

[0013] In the present disclosure and possible embodiments, the ratio of the molar amount of 1,4-butanediol to the molar amount of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol and 1,4-butanediol 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 1,4-butanediol.

[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 1,4-butanediol; and / or,

[0016] The transesterification reaction is carried out under nitrogen protection, with a reaction temperature of 160-200° C. and a reaction time of 5-10 hours.

[0017] In the present disclosure and possible embodiments, the transesterification reaction temperature is 200° C.; and / or,

[0018] The vacuum degree of the pre-polycondensation reaction is 5 kPa-20 kPa, the reaction temperature is 180-220° C., and the reaction time is 0.5-1 h.

[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 220° 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 PBS copolyester disclosed herein is obtained by copolymerizing 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol monomers. This monomer is synthesized based on 5-hydroxymethylfurfural, a green, renewable resource with a wide range of sources. The PBS copolyester synthesized using 5-hydroxymethylfurfural as a raw material can reduce dependence on petrochemical resources. In addition, because this monomer has a brand-new acetal ring structure, its introduction into PBS polyester can produce a modified PBS copolyester with a high glass transition temperature, thereby broadening the application areas of PBS polyester. At the same time, the preparation method of the PBS 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 PTS of Example 2 30 BS 70 DSC melting curve of copolyester;

[0033] Figure 2 PTS of Example 3 50 BS 50 DSC melting 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 PBS copolyester having a high glass transition temperature comprises a butylene succinate repeating unit represented by formula (I) and a 5-ethyl-2-(5-hydroxymethyl-2-furyl)-1,3-dioxane-5-methyl succinate repeating unit represented by formula (II);

[0036]

[0037] The PBS copolyester is named polybutylene succinate-co-5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl succinate, and its number average molecular weight is not less than 10,000 g / mol.

[0038] In the PBS copolyester, based on the total molar sum of all repeating units being 100%, preferably, the 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl succinate repeating units account for 5% to 50%, with the remainder being butylene succinate repeating structural units. More preferably, the 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl succinate repeating units account for 30% to 50%.

[0039] The polybutylene succinate-co-succinic acid 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl ester described in the present disclosure can be referred to as PTS x BS y , wherein T, S and B represent 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol, 1,4-butanediol and 1,4-butanediol, 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 succinate units and butylene succinate units in the PBS copolyester * 100%.

[0040] In the embodiment of the present disclosure, the PBS copolyester is obtained by bulk polymerization of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol with 1,4-butanediol and 1,4-butanediol. Specifically, 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol, 1,4-butanediol and 1,4-butanediol are put into a closed reactor, a catalyst is added, and an ester exchange reaction, a pre-condensation reaction and a final polycondensation reaction are carried out in sequence to obtain the PBS copolyester. Among them, the ratio of the molar amount of the 1,4-butanediol to the molar amount of the 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol and 1,4-butanediol is 1:1.2-3, and preferably the ratio is 1:1.5.

[0041] In the embodiment of the present disclosure, the catalyst is dibutyltin oxide, and the amount of the catalyst added 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 1,4-butanediol, preferably 0.1% to 0.3%.

[0042] In the embodiments of the present disclosure, the temperature of the transesterification reaction is 160-200°C, and the transesterification reaction time is 5 to 10 hours. Preferably, the transesterification reaction is carried out under the protection of nitrogen, and the transesterification reaction temperature is 200°C; the vacuum degree of the pre-polycondensation reaction is 5kPa-20kPa, the reaction temperature is 180 to 220°C, and the reaction time is 0.5 to 1h. Preferably, the vacuum degree of the pre-polycondensation reaction is 12kPa; the polycondensation reaction is carried out at a vacuum degree less than or equal to 60Pa, the polycondensation reaction temperature is 220°C, and the polycondensation reaction time is 2 to 5h. Preferably, the final polycondensation reaction is carried out at a vacuum degree of 60Pa.

[0043] In the present disclosure, when preparing the PBS copolyester, the 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol used has the structural formula:

[0044]

[0045] 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:

[0046] 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.

[0047] 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.

[0048] 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.

[0049] In the embodiments of the present disclosure, thermal transition analysis was performed using a TA company Q2000 differential scanning calorimeter at a heating rate of 10°C / min in a nitrogen atmosphere within a temperature range of -50 to 250°C.

[0050] Example 1

[0051] 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:

[0052] 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.

[0053] Example 2

[0054] 1. PTS 30 BS 70 Preparation of copolyester:

[0055] In this embodiment 2, the PTS 30 BS 70 It indicates that the molar proportion of the PTS block in the PBS copolyester is 30%.

[0056] 1) Preparation of PTS by melt polycondensation of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol, 1,4-butanediol and 1,4-butanedioic acid 30 BS 70 Copolyester:alkyd molar ratio is 1.5:1;

[0057] 2) Weigh 5.45 g of 5-ethyl-2-(5-hydroxymethyl-2-furyl)-1,3-dioxane-5-methanol, 4.73 g of 1,4-butanediol, and 5.90 g of 1,4-butanediol 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 set the transesterification reaction temperature to 180°C and the reaction time to 6 hours under a nitrogen atmosphere.

[0058] 3) The reaction temperature was raised to 220° C., the nitrogen protection was removed, and the pre-polycondensation reaction was continued at this temperature under a vacuum of 12 kPa for 0.5 h;

[0059] 4) The vacuum degree was adjusted to 60 Pa, the temperature was kept constant at 220 ° C, and the polycondensation reaction was continued for 2 hours to obtain the PTS 30 BS 70 Copolyester.

[0060] 2. PTS 30 BS 70 Copolyester DSC test:

[0061] 1) Weigh 5-10 mg of PTS prepared in Example 2 30 BS 70 The copolyester was placed in a differential scanning calorimeter to test the melting curve;

[0062] 2) Set the program of "heating-isothermal-cooling-isothermal-heating" with a temperature test range of -50 to 150°C and a heating and cooling rate of 10°C / min to obtain a melting curve.

[0063] Figure 1 PTS of Example 2 30 BS 70 Copolyester DSC melting curve, from the figure we can see that PTS 30 BS 70 The glass transition temperature (T g ) is -23.5°C, which is higher than the glass transition temperature of PBS -45°C.

[0064] Example 3

[0065] 1. PTS 50 BS 50 Preparation of copolyester:

[0066] 1) Preparation of PTS by melt polycondensation of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol, 1,4-butanediol and 1,4-butanedioic acid 50 BS 50 Copolyester:alkyd molar ratio is 1.5:1;

[0067] 2) Weigh 9.08 g of 5-ethyl-2-(5-hydroxymethyl-2-furyl)-1,3-dioxane-5-methanol, 3.38 g of 1,4-butanediol, and 5.90 g of 1,4-butanediol 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 set the transesterification reaction temperature to 180°C and the reaction time to 8 hours under a nitrogen atmosphere.

[0068] 3) The reaction temperature was raised to 220° C., the nitrogen protection was removed, and the pre-polycondensation reaction was continued at this temperature and a vacuum of 12 kPa for 0.5 h;

[0069] 4) The vacuum degree was adjusted to 60 Pa, the temperature was kept constant at 220 ° C, and the polycondensation reaction was carried out for 2 hours to obtain the PTS 50 BS 50 Copolyester.

[0070] 2. PTS 50 BS 50 Copolyester DSC test:

[0071] 1) Weigh 5-10 mg of PTS prepared in Example 3 50 BS 50 The copolyester was placed in a differential scanning calorimeter to test the melting curve;

[0072] 2) Set the program of "heating-isothermal-cooling-isothermal-heating" with a temperature test range of -50 to 150°C and a heating and cooling rate of 10°C / min to obtain a melting curve.

[0073] Figure 2 PTS of Example 3 50 BS 50 Copolyester DSC melting curve, from the figure we can see that PTS 50 BS 50 The glass transition temperature (Tg) of the copolyester is -16.3°C, which is higher than the glass transition temperature of PBS (-45°C).

[0074] 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 PBS copolyester with a high glass transition temperature, characterized in that: The PBS copolyester is a linear copolyester containing butylene succinate repeating units and 5-ethyl-2-(5-hydroxymethyl-2-furyl)-1,3-dioxane-5-methyl succinate repeating units, and its number average molecular weight is not less than 10,000 g / mol.

2. The PBS copolyester with a high glass transition temperature according to claim 1, wherein: Taking the total molar sum of all repeating units as 100%, the 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl succinate repeating unit accounts for 5%-50%, and the rest are butylene succinate repeating structural units.

3. The PBS copolyester with high glass transition temperature according to claim 2, wherein: The repeating unit of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methyl succinate accounts for 30% to 50%.

4. the preparation method of the described PBS copolyester of any one of claim 1-3, is characterized in that: The PBS copolyester is obtained by bulk polymerization of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol, 1,4-butanediol and 1,4-butanediol.

5. The preparation method of PBS copolyester according to claim 4, wherein The bulk polymerization method comprises: The 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol, 1,4-butanediol and 1,4-butanediol are put into a closed reactor, a catalyst is added, and the mixed system in the reactor sequentially undergoes an ester exchange reaction, a pre-polycondensation reaction and a polycondensation reaction to obtain the PBS copolyester.

6. The preparation method of the PBS copolyester according to claim 5, wherein: The ratio of the molar amount of the 1,4-butanediol to the molar amount of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol and 1,4-butanediol is 1:1.2-3.

7. The preparation method of the PBS copolyester according to claim 6, wherein: The ratio of the molar amount of the 1,4-butanediol to the molar amount of 5-ethyl-2-(5-hydroxymethyl-2-furan)-1,3-dioxane-5-methanol and 1,4-butanediol 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 1,4-butanediol.

8. The preparation method of PBS copolyester according to claim 7, wherein: 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 1,4-butanediol; and / or, The transesterification reaction is carried out under nitrogen protection, with a reaction temperature of 160-200° C. and a reaction time of 5-10 hours.

9. The method for preparing the PBS copolyester according to claim 8, wherein: The transesterification reaction temperature is 200° C.; and / or, The vacuum degree of the pre-polycondensation reaction is 5 kPa-20 kPa, the reaction temperature is 180-220° C., and the reaction time is 0.5-1 h.

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 220° C., and the polycondensation reaction time is 2 to 5 hours.

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