High-barrier, high-heat-resistant polyester materials, their preparation methods and applications

Abstract

This invention provides a high-barrier, high-heat-resistant polyester material, its preparation method, and its applications. The preparation method of the polyester material includes: in a protective atmosphere, subjecting a first mixed reaction system containing terephthalic acid and / or its esterified form, furanyl dicarboxylic acid and / or its esterified form, a diol, hydroxylated modified boron nitride nanosheets, and a first catalyst to an esterification or transesterification reaction to obtain an intermediate product; and subjecting a second mixed reaction system containing the intermediate product, a second catalyst, and a stabilizer to a polycondensation reaction under vacuum conditions to obtain the high-barrier, high-heat-resistant polyester material. This invention improves the heat resistance of the polyester by introducing an alicyclic diol and enhances its barrier properties by introducing hydroxylated modified boron nitride nanosheets and polymerizing them in situ. The resulting polyester material possesses advantages such as high barrier properties, high heat resistance, high safety, and high light transmittance. It can be made into polyester films and widely used in optical devices, food packaging materials, and other fields.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high molecular polyester materials, and particularly relates to a high-barrier high-heat-resistant polyester material and a preparation method and application thereof. BACKGROUND

[0002] High molecular thin films are generally made of organic high molecular polymers, are usually colorless and transparent, and have excellent mechanical properties, friction resistance, solvent resistance and the like. The commonly used high molecular thin film on the market is a polyethylene terephthalate film (PET film), which has excellent mechanical properties, good toughness, and higher impact strength than general thin films. However, due to the lack of rigidity in the structure of PET, its heat resistance is limited, and the glass transition temperature is about 80℃, which limits its application range at high temperatures. Moreover, the barrier property of the PET film is generally insufficient, and the barrier property is far from enough for some special packaging contents (such as beer, medicines, etc.), which limits the application of the PET film in food packaging. Therefore, it is crucial to further improve the barrier property and heat resistance of PET, and it has become a problem to be solved in the field. SUMMARY

[0003] To solve all or part of the above technical problems, the present application provides the following technical solutions:

[0004] The first aspect of the present application provides a preparation method of a high-barrier high-heat-resistant polyester material, which comprises:

[0005] In a protective atmosphere, a first mixed reaction system containing terephthalic acid and / or esterification product thereof, furandicarboxylic acid and / or esterification product thereof, a dihydric alcohol, hydroxyl-modified boron nitride nanosheet and a first catalyst is subjected to esterification or transesterification to obtain an intermediate product, wherein the dihydric alcohol comprises an alicyclic dihydric alcohol, and the alicyclic dihydric alcohol comprises a combination of one or more of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, tricyclodecane dimethanol and 4,4-bicyclohexanediol; the hydroxyl-modified boron nitride nanosheet is obtained by treating boron nitride nanosheet with mixed acid containing concentrated nitric acid and concentrated sulfuric acid;

[0006] A second mixed reaction system containing the intermediate product, a second catalyst and a stabilizer is subjected to polycondensation under vacuum to obtain a high-barrier high-heat-resistant polyester material.

[0007] The present application introduces alicyclic dihydric alcohol with rigid ring structure into polyester to improve the heat resistance of polyester; at the same time, furandicarboxylic acid and / or esterification product thereof and hydroxyl-modified boron nitride nanosheet are introduced to synergistically improve the barrier property of polyester.

[0008] In some embodiments, the total molar content of terephthalic acid and / or ester thereof and furandicarboxylic acid and / or ester thereof and the molar content of the dihydric alcohol in the first mixed reaction system are in a ratio of 1:1.1-2.0. If the molar content of the dihydric alcohol is low, the esterification or transesterification reaction is not complete, the efficiency is low, and the final polymerization is affected. If the molar ratio is too high, an end-capping effect will occur, limiting the increase in molecular weight.

[0009] In some embodiments, the amount of the hydroxyl-modified boron nitride nanosheet is 0.1wt%-1wt% of the theoretical polyester product. If the content of the hydroxyl-modified boron nitride nanosheet is low, the improvement of the polyester performance is not obvious. If the content is too high, the polyester polymerization efficiency will be affected.

[0010] In some embodiments, the reaction temperature of the esterification or transesterification reaction is 160°C-260°C.

[0011] In some embodiments, the reaction time of the esterification or transesterification reaction is 0.5h-6h.

[0012] In some embodiments, the reaction temperature of the polycondensation reaction is 260°C-300°C.

[0013] In some embodiments, the reaction time of the polycondensation reaction is 0.5h-5h.

[0014] In some embodiments, the polycondensation reaction is carried out under a vacuum degree of 20 Pa or less.

[0015] In some embodiments, the amount of the first catalyst, the second catalyst, and the stabilizer is 200ppm-1000ppm of the theoretical polyester product, respectively.

[0016] In some embodiments, the alicyclic dihydric alcohol further includes cyclohexanedimethanol.

[0017] In some preferred embodiments, the alicyclic dihydric alcohol includes 2,2,4,4-tetramethyl-1,3-cyclobutanediol. The four-membered ring in 2,2,4,4-tetramethyl-1,3-cyclobutanediol has a large rigidity, which can further increase the glass transition temperature of the polyester, i.e., improve the heat resistance of the polyester film; at the same time, it can also largely destroy the crystallinity of the copolyester, thereby improving the transparency of the polyester film. The polyester synthesized using 2,2,4,4-tetramethyl-1,3-cyclobutanediol as a raw material will not release bisphenol A during use, and thus can be safely used in food packaging materials. In embodiments in which the dihydric alcohol includes 2,2,4,4-tetramethyl-1,3-cyclobutanediol and also has other dihydric alcohols, the molar content of 2,2,4,4-tetramethyl-1,3-cyclobutanediol may, for example, be 30wt% or more of the total molar content of the dihydric alcohol.

[0018] The van der Waals force between the sheets of boron nitride is weak, so it can be exfoliated into a layered two-dimensional material by ball milling or the like, but due to inertness, the performance of the polyester prepared by directly compounding the exfoliated boron nitride is poor, so the boron nitride nanosheet needs to be hydroxylated before in-situ polymerization.

[0019] In some embodiments, the method for preparing the hydroxylated modified boron nitride nanosheet comprises: placing the boron nitride nanosheet in a mixed acid and treating it at 60-100°C for 6-12h, wherein the mixed acid contains concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:2-5. After the modification treatment is completed, washing is performed in deionized water, the solid product is collected by suction filtration, and drying is performed. Using the above method for modification treatment, hydroxylated modified boron nitride nanosheets with a sheet diameter of 1-30μm, a thickness of 1-10nm, and an aspect ratio of 800-1000 can be obtained. Such hydroxylated modified boron nitride nanosheets with large sheet size, small crystal lattice defects, high quality, and long-range orientation are beneficial to the directional arrangement of the nanosheets in the polyester and improve the barrier property.

[0020] In some embodiments, the terephthalic acid and / or ester thereof include one or more than two combinations of terephthalic acid and dimethyl terephthalate, but are not limited thereto.

[0021] In some embodiments, the furandicarboxylic acid and / or ester thereof include one or more than two combinations of furandicarboxylic acid and dimethyl furandicarboxylate, but are not limited thereto.

[0022] In some embodiments, the diol further includes a fatty diol.

[0023] In some embodiments, the fatty diol includes one or more than two combinations of ethylene glycol, propylene glycol, butanediol, pentanediol, and neopentyl glycol, but is not limited thereto.

[0024] In embodiments in which the diol further includes a diol other than the alicyclic diol, the mole percentage of the alicyclic diol is more than 30% of the diol.

[0025] The first catalyst can be any catalyst capable of catalyzing the esterification or transesterification reaction, and the present application does not make special limitations thereon. For example, in some embodiments, the first catalyst can include one or more than two combinations of zinc-based catalysts, manganese-based catalysts, titanium-based catalysts, and antimony-based catalysts, but is not limited thereto. In some typical embodiments, the first catalyst can include at least one of antimony trioxide, anhydrous zinc acetate, dibutyl tin oxide, and tetrabutyl titanate.

[0026] The second catalyst can catalyze the polycondensation reaction, and the present application does not make special limitation thereto. For example, in some embodiments, the second catalyst includes one or a combination of two or more of a titanium-based catalyst, a tin-based catalyst, an antimony-based catalyst, and a germanium-based catalyst, but is not limited thereto. In some typical embodiments, the second catalyst can include at least one of dibutyl tin oxide, antimony trioxide, stannous isooctoate, monobutyl tin triisooctoate, ethylene glycol antimony, antimony acetate, and polyethylene glycol antimony, tetrabutyl titanate, isobutyl titanate.

[0027] In some embodiments, the stabilizer includes a phosphorus-based stabilizer, for example, can include at least one of trimethyl phosphate and triphenyl phosphate, but is not limited thereto.

[0028] In some typical embodiments, the preparation method specifically includes: in a protective atmosphere, heating a first mixed reaction system containing terephthalic acid and / or esterification products thereof, furandicarboxylic acid and / or esterification products thereof, an alicyclic diol, an optional aliphatic diol, a hydroxyl-modified boron nitride nanosheet, and a first catalyst to 160°C to 260°C, and starting stirring, reacting for about 0.5 to 6 hours, when the amount of methanol or the amount of water reaches 95wt% of the theoretical mass, adding a second catalyst and a stabilizer to the reaction product, increasing the temperature to 260°C to 300°C, and vacuumizing the reaction system to below 20 Pa to perform a polycondensation reaction, reacting for 0.5 to 5 hours, to obtain the high-barrier high-heat-resistant polyester.

[0029] In some embodiments, the protective atmosphere can be formed by any one of inert gases such as argon, nitrogen, etc. or a mixed gas thereof.

[0030] The second aspect of the present application provides a high-barrier high-heat-resistant polyester material prepared by the preparation method of the high-barrier high-heat-resistant polyester material according to any one of the technical solutions described above.

[0031] The third aspect of the present application provides a high-barrier high-heat-resistant polyester material, which includes:

[0032] a polyester containing 25% to 75% by mole of repeating units derived from terephthalic acid and / or esterification products thereof, 25% to 75% by mole of repeating units derived from furandicarboxylic acid and / or esterification products thereof, and 30% to 100% by mole of repeating units derived from an alicyclic diol including a combination of one or more of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, tricyclodecane dimethanol, and 4,4-bicyclohexanediol;

[0033] 0.1wt%~1wt% of hydroxylated modified boron nitride nanosheets, wherein the hydroxylated modified boron nitride nanosheets are obtained by treating boron nitride nanosheets with a mixed acid containing concentrated nitric acid and concentrated sulfuric acid.

[0034] In some embodiments, the polyester also contains 0% to 70% molar percentage of repeating units derived from fatty diols.

[0035] In some embodiments, the high-barrier, high-heat-resistant polyester material is prepared by melt polycondensation of raw materials including terephthalic acid and / or its esters, furanyl dicarboxylic acid and / or its esters, alicyclic diols, optionally fatty diols, and hydroxylated modified boron nitride nanosheets.

[0036] A fourth aspect of the present invention provides a high-barrier, high-heat-resistant polyester material, wherein the raw materials of the high-barrier, high-heat-resistant polyester material include terephthalic acid and / or its esterified form, furanyl dicarboxylic acid and / or its esterified form, a diol, hydroxylated modified boron nitride nanosheets, a first catalyst, a second catalyst, and a stabilizer; wherein the diol includes alicyclic diols.

[0037] In some embodiments, the total molar content of terephthalic acid and / or its esterified form and furanyl dicarboxylic acid and / or its esterified form is in the ratio of the molar content of the diol to 1:1.1~2.0.

[0038] In some embodiments, the amount of the hydroxylated boron nitride nanosheets is 0.1 wt% to 1 wt% of the theoretical polyester product mass.

[0039] In some embodiments, the amounts of the first catalyst, the second catalyst, and the stabilizer are 200 ppm to 1000 ppm of the theoretical polyester product mass, respectively.

[0040] The further selection of terephthalic acid and / or its esters, furanyl dicarboxylic acid and / or its esters, alicyclic diols, and fatty diols, as well as the further features of the hydroxylated modified boron nitride nanosheets, as described in the third and fourth aspects of this invention, have been described in detail in the "Preparation Method of a High Barrier and High Heat Resistance Polyester Material" provided in the first aspect of this invention, and will not be repeated here.

[0041] The fifth aspect of the present invention provides a polyester article, which may be mainly made of the high-barrier and high-heat-resistant polyester material, and may be in various forms such as sheets, films, and plates.

[0042] In some embodiments, the high-barrier, high-heat-resistant polyester material can be further processed to form polyester chips. For example, the method for preparing the polyester chips may include:

[0043] The high-barrier, high-heat-resistant polyester material is fed into a co-rotating twin-screw extruder for melt extrusion and granulation to prepare polyester chips.

[0044] The operating parameters of the co-rotating twin-screw extruder include: barrel temperature of 250℃~290℃ and die temperature of 260℃~290℃.

[0045] In some embodiments, the high-barrier, high-heat-resistant polyester material can be further processed to form a polyester film. For example, the method for preparing the polyester film may include:

[0046] The high-barrier, high-heat-resistant polyester material is added to a twin-screw extruder and melt-extruded at 260°C to 290°C. The molten fluid is then cast onto a rotating cooling roller to form a cast plastic sheet with a thickness of 1000μm to 5500μm.

[0047] The cast plastic sheet is preheated to 100-140°C and then stretched longitudinally by 2-5 times. It is then preheated again to 100-140°C and stretched laterally by 3-4.5 times to obtain the polyester film material.

[0048] Through the aforementioned specific membrane stretching technology, shear force-induced orientation causes hydroxylated boron nitride nanosheets to align in the polyester, further improving barrier properties.

[0049] In some embodiments, the glass transition temperature of the polyester film is above 85°C, preferably above 100°C, which means it has good heat resistance.

[0050] In some embodiments, the O2 transmittance of the polyester film is ≤0.0260×10⁻⁶. -10 cm 3 ·cm / cm 2 CO2 permeability ≤ 0.0550 × 10⁻⁶ ·s·cm Hg -10 cm 3 ·cm / cm 2 It has good barrier properties, with a strength of ·s·cm Hg.

[0051] In some embodiments, the light transmittance of the polyester film is 88% or more, preferably 90% or more, which means it has good transparency.

[0052] In some embodiments, the thickness of the polyester film is 20μm to 1000μm.

[0053] In some embodiments, the high-barrier, high-heat-resistant polyester material can be further processed to form a polyester sheet, referring to the preparation method of the polyester film material.

[0054] In some embodiments, the polyester product has a multilayer composite film structure, the multilayer composite film structure including a first structural layer and a second structural layer stacked together, the first structural layer including the polyester film material.

[0055] Furthermore, the first structural layer and the second structural layer can be combined by means of bonding, pressing, hot melt welding, laser welding, etc., and are not limited to these methods.

[0056] The sixth aspect of the present invention provides the application of the high-barrier, high-heat-resistant polyester material described in any of the technical solutions in the preparation of food packaging materials or optical devices.

[0057] Compared with the prior art, the present invention has at least the following beneficial effects:

[0058] (1) The present invention introduces rigid alicyclic diols into polyester, which can significantly improve the heat resistance of polyester compared with long-chain aliphatic diols.

[0059] (2) The present invention also introduces furan dicarboxylic acid and / or its esterifications, whose unique furan ring chemical structure gives the prepared furan-based polyester excellent barrier properties;

[0060] (3) Boron nitride nanosheets, as two-dimensional sheet fillers, can extend the diffusion path of small molecules (such as oxygen and water vapor) in materials. However, when simply blended, boron nitride nanosheets are prone to agglomeration and random orientation, resulting in limited effectiveness. Therefore, this invention adds hydroxylated modified boron nitride nanosheets during polyester synthesis and achieves more uniform dispersion and stronger interfacial bonding through in-situ polymerization. The introduction of hydroxylated modified boron nitride nanosheets further improves the barrier properties of polyester.

[0061] (4) In the preparation process of polyester film, the present invention further adopts a specific film stretching technology, and the shear force induces the boron nitride nanosheets to be oriented in the polyester. External gases or liquids (such as water vapor, oxygen, etc.) grow through the effective path of the polyester, making it difficult for external gases or liquids to pass through, thus giving the polyester excellent barrier properties. Attached Figure Description

[0062] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0063] Figure 1 This is the NMR spectrum of the high-barrier, high-heat-resistant polyester material obtained in Example 2 of this invention;

[0064] Figure 2 This is the DSC spectrum of the high-barrier, high-heat-resistant polyester material obtained in Example 2 of this invention;

[0065] Figure 3 This is a graph showing the ultraviolet transmittance of a polyester film made from a high-barrier, high-heat-resistant polyester material according to Example 2 of the present invention. Detailed Implementation

[0066] The invention will be more fully understood through the following detailed description, which should be read in conjunction with the accompanying drawings. Detailed embodiments of the invention are disclosed herein; however, it should be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, the specific functional details disclosed herein should not be construed as limiting, but rather as the basis for the claims and as intended to teach those skilled in the art to employ the representative basis of the invention in different ways in any suitable detailed embodiment.

[0067] In addition, unless otherwise specified, all raw materials used in the following embodiments can be purchased from the market or other sources, and all production and testing equipment used are known in the art, as are the testing methods used.

[0068] In the following examples, the 1H NMR spectrum of the polyester was determined using a nuclear magnetic resonance spectrometer (Bruker, 600MHz AVANCE NEO 600) with deuterated trifluoroacetic acid (CF3COOD) as the solvent.

[0069] In the following examples, the thermal conversion properties of polyester were tested using a differential scanning calorimeter (METTLER TOLEDO DSC3+). Test conditions: N2 atmosphere, temperature range of 25℃~250℃, heating rate of 10℃ / min.

[0070] In the following examples, the transmittance of polyester films was determined using a UV-Vis-NIR spectrophotometer (Lambda 950) with a wavelength range of 200-800 nm and the samples were polyester films with a thickness of 200 μm.

[0071] In the following examples, the barrier properties of polyester were tested using a differential pressure gas permeation apparatus (VAC V2) to determine the O2 and CO2 permeability coefficients.

[0072] The method for preparing hydroxylated modified boron nitride nanosheets used in the following specific embodiments of the present invention is as follows:

[0073] Concentrated nitric acid (HNO3) and concentrated sulfuric acid (H2SO4) were slowly mixed in an ice-water bath at a volume ratio of 1:3 to prepare a mixed acid. A certain amount of exfoliated boron nitride nanosheets was then added to the mixed acid, and the mixture was magnetically stirred and refluxed at 80°C for 8 hours. The reaction product was then washed in deionized water, filtered to collect the solid product, and dried to obtain hydroxylated modified boron nitride nanosheets. The obtained hydroxylated modified boron nitride nanosheets had a diameter between 1 μm and 30 μm, a thickness between 1 nm and 10 nm, and an aspect ratio between 800 and 1000.

[0074] Example 1

[0075] Dimethyl terephthalate, dimethyl furanate, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and 1,4-cyclohexanediethanol were added to a three-necked flask in a molar ratio of 0.75:0.25:0.3:0.8. Then, 0.1 wt% of hydroxylated boron nitride nanosheets (based on the theoretical polyester product mass) were added, followed by 200 ppm of zinc acetate catalyst (based on the theoretical polyester product mass). Under continuous N2 purging protection, the temperature was gradually increased to 180°C with mechanical stirring, and then gradually increased to 260°C to carry out the transesterification reaction. When the amount of methanol reached more than 95 wt% of the theoretical mass, the transesterification reaction was terminated to obtain the reaction product.

[0076] Then, 200 ppm of antimony trioxide catalyst and 200 ppm of trimethyl phosphate stabilizer (based on the theoretical polyester product mass) were added to the above reaction product, and the temperature was slowly raised to 280°C. At the same time, a vacuum pump was connected, and the vacuum was evacuated to below 20 Pa within 30 minutes to carry out the polycondensation reaction for 5 hours. After the reaction was completed, the vacuum pump was turned off, and N2 was introduced to restore the pressure inside the bottle to atmospheric pressure. The product, namely the high-barrier and high-heat-resistant polyester material, was then taken out.

[0077] Example 2

[0078] Terephthalic acid, dimethyl furanate, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and 1,4-cyclohexanediethanol were added to a three-necked flask in a molar ratio of 0.5:0.5:0.3:0.8. Then, 0.1 wt% of hydroxylated boron nitride nanosheets (based on the theoretical polyester product mass) were added, followed by 500 ppm of tetrabutyl titanate (based on the theoretical polyester product mass). Under continuous N2 purging protection, the temperature was gradually increased to 180°C with mechanical stirring, and then gradually increased to 250°C to carry out the transesterification reaction. When the methanol and water content reached more than 95 wt% of the theoretical mass, the transesterification reaction was terminated to obtain the reaction product.

[0079] Then, 500 ppm of antimony trioxide catalyst and 500 ppm of triphenyl phosphate stabilizer (based on the theoretical polyester product mass) were added to the above reaction product, and the temperature was slowly raised to 270°C. At the same time, a vacuum pump was connected, and the vacuum was evacuated to below 20 Pa within 30 min to carry out the polycondensation reaction for 3 h. After the reaction was completed, the vacuum pump was turned off, and N2 was introduced to restore the pressure inside the bottle to atmospheric pressure. The product, namely the high-barrier and high-heat-resistant polyester material, was then taken out.

[0080] Example 3

[0081] Dimethyl terephthalate, furanyl dicarboxylic acid, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and 1,4-cyclohexanediethanol were added to a three-necked flask in a molar ratio of 0.25:0.75:0.3:0.8. Then, 0.1 wt% (by weight of the theoretical polyester product) of hydroxylated modified boron nitride nanosheets were added, followed by 1000 ppm (by weight of the theoretical polyester product) of anhydrous zinc acetate. Under continuous N2 purging protection, the temperature was gradually increased to 180°C with mechanical stirring, and then gradually increased to 240°C to carry out the transesterification reaction. When the methanol and water content reached more than 95 wt% (by weight of the theoretical mass), the transesterification reaction was terminated, yielding the reaction product.

[0082] Then, 1000 ppm of tetrabutyl titanate catalyst and 1000 ppm of triphenyl phosphate stabilizer (based on the theoretical polyester product mass) were added to the above reaction product, and the temperature was slowly raised to 260°C. At the same time, a vacuum pump was connected, and the vacuum was evacuated to below 20 Pa within 30 min to carry out the polycondensation reaction for 0.5 h. After the reaction was completed, the vacuum pump was turned off, and N2 was introduced to restore the pressure inside the bottle to atmospheric pressure. The product, namely the high-barrier and high-heat-resistant polyester material, was then taken out.

[0083] Example 4

[0084] Terephthalic acid, furanyl dicarboxylic acid, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and 1,4-cyclohexanediethanol were added to a three-necked flask in a molar ratio of 0.5:0.5:0.3:0.8. Then, 0.3 wt% (by weight of the theoretical polyester product) of hydroxylated modified boron nitride nanosheets were added, followed by 1000 ppm (by weight of the theoretical polyester product) of anhydrous zinc acetate. Under continuous N2 purging protection, the temperature was gradually increased to 180°C with mechanical stirring, and then gradually increased to 250°C to carry out the transesterification reaction. When the amount of water produced reached more than 95% of the theoretical mass, the transesterification reaction was terminated, yielding the reaction product.

[0085] Then, 1000 ppm of the catalyst dibutyltin oxide and 1000 ppm of the stabilizer trimethyl phosphate (based on the theoretical polyester product mass) were added to the above reaction product, and the temperature was slowly raised to 270°C. At the same time, a vacuum pump was connected, and the vacuum was evacuated to below 20 Pa within 30 min to carry out the polycondensation reaction for 1 h. After the reaction was completed, the vacuum pump was turned off, and N2 was introduced to restore the pressure inside the bottle to atmospheric pressure. The product, namely the high-barrier and high-heat-resistant polyester material, was then taken out.

[0086] Example 5

[0087] Terephthalic acid, furanyl dicarboxylic acid, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and 1,4-cyclohexanediethanol were added to a three-necked flask in a molar ratio of 0.5:0.5:0.3:0.8. Then, 0.6 wt% (by weight of the theoretical polyester product) of hydroxylated modified boron nitride nanosheets were added, followed by 1000 ppm (by weight of the theoretical polyester product) of antimony trioxide. Under continuous N2 purging protection, the temperature was gradually increased to 180°C with mechanical stirring, and then gradually increased to 250°C to carry out the transesterification reaction. When the amount of water produced reached more than 95 wt% (by weight of the theoretical mass), the transesterification reaction was terminated, yielding the reaction product.

[0088] Then, 1000 ppm of the catalyst dibutyltin oxide and 1000 ppm of the stabilizer triphenyl phosphate (based on the theoretical polyester product mass) were added to the above reaction product, and the temperature was slowly raised to 270°C. At the same time, a vacuum pump was connected, and the vacuum was evacuated to below 20 Pa within 30 min to carry out the polycondensation reaction for 1 h. After the reaction was completed, the vacuum pump was turned off, and N2 was introduced to restore the pressure inside the bottle to atmospheric pressure. The product, namely the high-barrier and high-heat-resistant polyester material, was then taken out.

[0089] Example 6

[0090] Dimethyl terephthalate, dimethyl furanate, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and 1,4-cyclohexanediethanol were added to a three-necked flask in a molar ratio of 0.5:0.5:0.3:0.8. Then, 1.0 wt% of hydroxylated boron nitride nanosheets (based on the theoretical polyester product mass) were added, followed by 1000 ppm of dibutyltin oxide (based on the theoretical polyester product mass). Under continuous N2 purging protection, the temperature was gradually increased to 180°C with mechanical stirring, and then gradually increased to 250°C to carry out the transesterification reaction. When the amount of methanol reached more than 95 wt% of the theoretical mass, the transesterification reaction was terminated to obtain the reaction product.

[0091] Then, 1000 ppm of stannous isooctanoate catalyst and 1000 ppm of triphenyl phosphate stabilizer (based on the theoretical polyester product mass) were added to the above reaction product, and the temperature was slowly raised to 270°C. At the same time, a vacuum pump was connected, and the vacuum was evacuated to below 20 Pa within 30 min to carry out the polycondensation reaction for 2 h. After the reaction was completed, the vacuum pump was turned off, and N2 was introduced to restore the pressure inside the bottle to atmospheric pressure. The product, namely the high-barrier and high-heat-resistant polyester material, was then taken out.

[0092] Example 7

[0093] Dimethyl terephthalate, dimethyl furanate, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and ethylene glycol were added to a three-necked flask in a molar ratio of 0.5:0.5:0.3:1.7. Then, 0.6 wt% of hydroxylated boron nitride nanosheets (based on the theoretical polyester product mass) were added, followed by 1000 ppm of dibutyltin oxide (based on the theoretical polyester product mass). Under continuous N2 purging protection, the temperature was gradually increased to 180°C with mechanical stirring. The temperature was then gradually increased to 160°C to carry out the transesterification reaction. When the amount of methanol reached more than 95 wt% of the theoretical mass, the transesterification reaction was terminated to obtain the reaction product.

[0094] Then, 1000 ppm of germanium oxide catalyst and 1000 ppm of triphenyl phosphate stabilizer (based on the theoretical polyester product mass) were added to the above reaction product, and the temperature was slowly raised to 260°C. At the same time, a vacuum pump was connected, and the vacuum was evacuated to below 20 Pa within 30 min to carry out the polycondensation reaction for 1 h. After the reaction was completed, the vacuum pump was turned off, and N2 was introduced to restore the pressure inside the bottle to atmospheric pressure. The product, namely the high-barrier and high-heat-resistant polyester material, was then taken out.

[0095] Example 8

[0096] Dimethyl terephthalate, dimethyl furanate, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and propylene glycol were added to a three-necked flask in a molar ratio of 0.5:0.5:0.3:1.3. Then, 0.6 wt% of hydroxylated boron nitride nanosheets (based on the theoretical polyester product mass) were added, followed by 1000 ppm of dibutyltin oxide (based on the theoretical polyester product mass). Under continuous N2 purging protection, the temperature was gradually increased to 180°C with mechanical stirring. The transesterification reaction was then carried out by gradually increasing the temperature to 180°C. When the amount of methanol reached more than 95 wt% of the theoretical mass, the transesterification reaction was terminated, and the reaction product was obtained.

[0097] Then, 1000 ppm of the catalyst antimony glycolate and 1000 ppm of the stabilizer triphenyl phosphate (based on the theoretical polyester product mass) were added to the above reaction product, and the temperature was slowly raised to 260°C. At the same time, a vacuum pump was connected, and the vacuum was evacuated to below 20 Pa within 30 min to carry out the polycondensation reaction for 1 h. After the reaction was completed, the vacuum pump was turned off, and N2 was introduced to restore the pressure inside the bottle to atmospheric pressure. The product, namely the high-barrier and high-heat-resistant polyester material, was then taken out.

[0098] Example 9

[0099] Dimethyl terephthalate, dimethyl furanate, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and butanediol were added to a three-necked flask in a molar ratio of 0.5:0.5:0.3:1.3. Then, 0.6 wt% of hydroxylated boron nitride nanosheets (based on the theoretical polyester product mass) were added, followed by 1000 ppm of dibutyltin oxide (based on the theoretical polyester product mass). Under continuous N2 purging protection, the temperature was gradually increased to 180°C and mechanical stirring was started. The transesterification reaction was then carried out by gradually increasing the temperature to 180°C. When the amount of methanol reached more than 95 wt% of the theoretical mass, the transesterification reaction was terminated, and the reaction product was obtained.

[0100] Then, 1000 ppm of the theoretical polyester product mass of the catalyst isobutyl titanate and 1000 ppm of the theoretical polyester product mass of the stabilizer triphenyl phosphate are added to the above reaction product, and the temperature is slowly raised to 260°C. At the same time, a vacuum pump is connected, and the vacuum is evacuated to below 20 Pa within 30 min to carry out the polycondensation reaction for 1 h. After the reaction is completed, the vacuum pump is turned off, N2 is introduced to restore the pressure inside the bottle to atmospheric pressure, and the product is taken out, which is the high-barrier and high-heat-resistant polyester material.

[0101] Example 10

[0102] Dimethyl terephthalate, dimethyl furanate, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and neopentyl glycol were added to a three-necked flask in a molar ratio of 0.5:0.5:0.3:1.3. Then, 0.6 wt% (by weight of the theoretical polyester product) of hydroxylated modified boron nitride nanosheets were added, followed by 1000 ppm (by weight of the theoretical polyester product) of dibutyltin oxide. Under continuous N2 purging protection, the temperature was gradually increased to 180 °C with mechanical stirring, and then gradually increased to 190 °C for transesterification. When the methanol or water output reached more than 95 wt% (by weight of the theoretical mass), the transesterification reaction was terminated, yielding the reaction product.

[0103] Then, 1000 ppm of antimony acetate catalyst and 1000 ppm of triphenyl phosphate stabilizer (based on the theoretical polyester product mass) were added to the above reaction product, and the temperature was slowly raised to 260°C. At the same time, a vacuum pump was connected, and the vacuum was evacuated to below 20 Pa within 30 min to carry out the polycondensation reaction for 1 h. After the reaction was completed, the vacuum pump was turned off, and N2 was introduced to restore the pressure inside the bottle to atmospheric pressure. The product, namely the high-barrier and high-heat-resistant polyester material, was then taken out.

[0104] Example 11

[0105] The only difference between Example 11 and Example 2 is that 2,2,4,4-tetramethyl-1,3-cyclobutanediol is replaced with tricyclodecanediethanol, and the polycondensation temperature is 300°C. The rest of the process is the same as in Example 2 and will not be repeated here.

[0106] Example 12

[0107] The only difference between Example 12 and Example 2 is that 2,2,4,4-tetramethyl-1,3-cyclobutanediol is replaced with 4,4-dicyclohexanediol, and the polycondensation temperature is 290°C; all other conditions remain unchanged. The rest of the procedures are the same as in Example 2 and will not be repeated here.

[0108] Example 13

[0109] This embodiment provides a polyester film and its preparation method, specifically including:

[0110] The high-barrier, high-heat-resistant polyester material (poly(2,2,4,4-tetramethyl-1,3-cyclobutanediol-1,4-cyclohexanediethanol ester) prepared in Example 1 was fed into a twin-screw extruder. The extruder speed was set to 45 r / min, and the temperatures of each zone of the extruder were set to 272.5℃ for zone 1, 278℃ for zone 2, 278℃ for zone 3, 278℃ for zone 4, and 278℃ for zone 5. The polyester was melt-extruded at 278℃ and cast onto a cooling drum to obtain polyester sheets with a thickness of 1000 μm to 5500 μm.

[0111] The above-mentioned polyester sheet is heated to 100°C, then stretched longitudinally by 2 to 5 times, then heated again to 140°C and stretched transversely by 3 to 4.5 times, and then heat-set at 200°C to 260°C to obtain a high heat-resistant polyester film with a thickness of 100μm to 1200μm.

[0112] Tests were conducted on a 200 μm thick polyester film, and the film transmittance at a wavelength of 700 nm was found to be over 90%.

[0113] Example 14

[0114] This embodiment provides a polyester film and its preparation method, specifically including:

[0115] The high-barrier, high-heat-resistant polyester material (poly(2,2,4,4-tetramethyl-1,3-cyclobutanediol)) prepared in Example 7 was fed into a twin-screw extruder. The extruder speed was set to 45 r / min, and the temperatures of each zone of the extruder were set as follows: Zone 1 260°C, Zone 2 270°C, Zone 3 275°C, Zone 4 275°C, and Zone 5 275°C. The polyester was melt-extruded at 275°C and cast onto a cooling drum to obtain polyester sheets with a thickness of 1000 μm to 5500 μm.

[0116] The polyester sheet is heated to 100°C and stretched longitudinally by 2 to 5 times. Then it is heated to 120°C and stretched transversely by 3 to 5 times. After that, it is heat-set at 200°C to 260°C to obtain a high heat-resistant polyester film with a thickness of 100μm to 1200μm.

[0117] Example 15

[0118] This embodiment provides a polyester film and its preparation method, specifically including:

[0119] The high-barrier, high-heat-resistant polyester material (poly(tricyclodecanediethanol terephthalate) 1,4-cyclohexanediethanol ester) prepared in Example 11 was fed into a twin-screw extruder. The extruder speed was set to 45 r / min, and the temperatures of each zone of the extruder were set as follows: Zone 1: 275°C, Zone 2: 280°C, Zone 3: 285°C, Zone 4: 290°C, and Zone 5: 290°C. The polyester was melt-extruded at 290°C and cast onto a cooling drum to obtain polyester sheets with a thickness of 1000 μm to 5500 μm.

[0120] The above-mentioned polyester sheet is heated to 120°C, then stretched longitudinally by 2 to 5 times, then heated again to 140°C and stretched transversely by 3 to 4.5 times, and then heat-set at 200°C to 260°C to obtain a high heat-resistant polyester film with a thickness of 100μm to 1200μm.

[0121] Example 16

[0122] This embodiment provides a composite film comprising a first structural layer and a second structural layer stacked sequentially, the first and second structural layers being bonded together by adhesive. The first structural layer is a high-heat-resistant, high-barrier polyester film of Example 1 with a thickness of 100 μm, and the second structural layer is a 100 μm thick PET base film. The composite film provided in this embodiment can be used for food packaging.

[0123] Comparative Example 1

[0124] The only difference between Comparative Example 1 and Example 2 is that boron nitride nanosheets were not added to the transesterification reaction system. The rest of the procedures were the same as in Example 2 and will not be repeated here.

[0125] Comparative Example 2

[0126] The only difference between Comparative Example 2 and Example 2 is that the hydroxylated boron nitride nanosheets were replaced with the same amount of unmodified boron nitride nanosheets. The rest of the procedures were the same as in Example 2 and will not be repeated here.

[0127] Comparative Example 3

[0128] The only difference between Comparative Example 3 and Example 7 is that 2,2,4,4-tetramethyl-1,3-cyclobutanediol was not added, and only ethylene glycol was used. The molar ratio of ethylene glycol in Comparative Example 3 is equal to the total molar ratio of 2,2,4,4-tetramethyl-1,3-cyclobutanediol to ethylene glycol in Example 7.

[0129] The polyester materials of Examples 1-12 and Comparative Examples 1-3 were used to prepare 200 μm thick polyester films according to the film preparation method in Example 13, and the transmittance and other related properties were tested. The test results are shown in Table 1.

[0130] Figure 1 This is the NMR spectrum of the high-barrier, high-heat-resistant polyester material prepared in Example 2. Figure 2 This is the DSC spectrum of the high-barrier, high-heat-resistant polyester material prepared in Example 2. Figure 3 This is a graph showing the ultraviolet transmittance of a polyester film made from the high-barrier, high-heat-resistant polyester material of Example 2.

[0131] The present invention tests the relevant properties of the polyester materials or polyester films in the above embodiments and comparative examples, and the test results are shown in Table 1.

[0132] Table 1. Relevant performance data of the polyesters prepared in the Examples and Comparative Examples.

[0133] ;

[0134] In addition, the inventors of this case also conducted experiments with other raw materials, processes and conditions described in this specification, referring to the aforementioned embodiments, and the resulting polyester and polyester products all have good heat resistance and barrier properties.

[0135] In summary, this invention improves the heat resistance of polyester by introducing rigid alicyclic diols, which significantly increase the glass transition temperature compared to long-chain alicyclic diols, thus meeting the heat resistance requirements of practical applications. Furthermore, the barrier properties of the polyester are further enhanced with increasing furanyl dicarboxylic acid residue content. Additionally, hydroxylated boron nitride nanosheets, introduced into the polyester through in-situ polymerization, can significantly improve the barrier properties of the polyester.

[0136] All aspects, embodiments, features, and examples of this invention should be considered illustrative and used to explain and illustrate the invention, but not to limit the invention. The scope of the invention is defined only by the claims.

[0137] Although the invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the invention, and that elements of the described embodiments can be substituted with substantially equivalents. Furthermore, many modifications can be made without departing from the scope of the invention to adapt particular situations or materials to the teachings of the invention. Therefore, this invention is not intended to be limited to the specific embodiments disclosed for carrying out the invention, but rather is intended to encompass all embodiments falling within the scope of the appended claims.

Claims

1. A method for preparing a high-barrier high-heat-resistant polyester material, characterized by, The application relates to a preparation method of a high-barrier high-heat-resistance polyester material. The first mixed reaction system containing terephthalic acid and / or esterification products thereof, furandicarboxylic acid and / or esterification products thereof, a dihydric alcohol, hydroxyl-modified boron nitride nanosheets and a first catalyst is subjected to esterification or ester exchange in a protective atmosphere to obtain an intermediate product, wherein the dihydric alcohol is alicyclic dihydric alcohol, the alicyclic dihydric alcohol includes at least one of cyclohexane dimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, tricyclodecane dimethanol and 4,4-bicyclohexanediol; the hydroxyl-modified boron nitride nanosheets are obtained by treating boron nitride nanosheets with mixed acid containing concentrated nitric acid and concentrated sulfuric acid, and the amount of the hydroxyl-modified boron nitride nanosheets is 0.1wt%-1wt% of the mass of the theoretical polyester product; A second mixed reaction system containing the intermediate product, a second catalyst and a stabilizer is subjected to polycondensation under vacuum to obtain the high-barrier high-heat-resistance polyester material.

2. The method of claim 1, wherein: In the first mixed reaction system, the ratio of the total molar content of the terephthalic acid and / or esterification products thereof and the furandicarboxylic acid and / or esterification products thereof to the molar content of the dihydric alcohol is 1:1.1-2.

0.

3. The method of claim 1, wherein: The reaction temperature of the esterification or ester exchange is 160 DEG C-260 DEG C, and / or the reaction time of the esterification or ester exchange is 0.5h-6h.

4. The method of claim 1, wherein: The reaction temperature of the polycondensation is 260 DEG C-300 DEG C, and / or the reaction time of the polycondensation is 0.5h-5h.

5. The method of claim 1, wherein: The amounts of the first catalyst, the second catalyst and the stabilizer are respectively 200ppm-1000ppm of the mass of the theoretical polyester product.

6. The method of claim 1, wherein: The terephthalic acid and / or esterification products thereof include one or more than two combinations of terephthalic acid and dimethyl terephthalate.

7. The method of claim 1, wherein: The furandicarboxylic acid and / or esterification products thereof include furandicarboxylic acid and / or dimethyl furandicarboxylate.

8. The method of claim 1, wherein: The first catalyst includes one or more than two combinations of zinc-based catalysts, manganese-based catalysts, titanium-based catalysts and antimony-based catalysts.

9. The method of claim 1, wherein: The second catalyst includes one or more than two combinations of titanium-based catalysts, tin-based catalysts, antimony-based catalysts and germanium-based catalysts.

10. The method of claim 1, wherein: The stabilizer includes phosphorus-based stabilizers.

11. The method of claim 1, wherein, The preparation method of the hydroxyl-modified boron nitride nanosheets includes the following steps: placing boron nitride nanosheets in mixed acid, and treating at 60 DEG C-100 DEG C for 6h-12h, wherein the mixed acid contains concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:2-5.

12. The method of claim 1, wherein: The hydroxyl-modified boron nitride nanosheets have a sheet diameter of 1mu m-30mu m, a thickness of 1nm-10nm and an aspect ratio of 800-1000.

13. A high barrier, high heat resistant polyester material, characterized in that, The high-barrier high-heat-resistance polyester material is prepared by the preparation method in any one of claims 1-12.

14. A high barrier, high heat resistant polyester material, characterized in that, The application relates to a preparation method of a high-barrier high-heat-resistance polyester material. polyesters containing 25-75 mole percent of repeating units derived from terephthalic acid and / or esters thereof, 25-75 mole percent of repeating units derived from furandicarboxylic acid and / or esters thereof, 30-100 mole percent of repeating units derived from a cycloaliphatic diol, including cyclohexanedimethanol, and at least one of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, tricyclodecanedimethanol, 4,4-bicyclohexanediol; 0.1wt%-1wt% of hydroxyl-modified boron nitride nanosheets, which are obtained by treating boron nitride nanosheets with a mixed acid containing concentrated nitric acid and concentrated sulfuric acid.

15. Use of the high-barrier high-heat-resistance polyester material of any one of claims 13-14 in the preparation of food packaging materials or optical devices.

16. A process for the preparation of a polyester chip, characterized in that, including, feeding the high-barrier high-heat-resistance polyester material of any one of claims 13-14 into a co-rotating twin-screw extruder for melt extrusion and granulation to prepare polyester chips; wherein the working parameters of the co-rotating twin-screw extruder include: barrel temperature of 250-290℃, and die temperature of 260-290℃.

17. A method of making a polyester film material, characterized by, including, feeding the high-barrier high-heat-resistance polyester material of any one of claims 13-14 into a twin-screw extruder, melt extruding at 260-290℃, and casting the melt fluid onto a rotating cooling roller to obtain a cast thick sheet with a thickness of 1000-5500μm; after preheating the cast thick sheet to 100-140℃, longitudinally stretching it by 2-5 times, and then again preheating it to 100-140℃ and transversely stretching it by 3-4.5 times, a polyester film material is obtained.

18. A polyester film characterized by: The polyester film is made of the high-barrier, high-heat-resistant polyester material as described in any one of claims 13-14; the glass transition temperature of the polyester film is above 85 °C, and the O2 transmittance is ≤0.0260×10⁻⁶. -10 cm 3 ·cm / cm 2 CO2 permeability ≤ 0.0550 × 10⁻⁶ ·s·cm Hg -10 cm 3 ·cm / cm 2 ·s·cmHg.

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