Modified copolyester as well as preparation method and application thereof

Abstract

The invention relates to the field of polyester, and discloses modified copolyester as well as a preparation method and application thereof. The semi-crystallization time of the modified copolyester at 170 DEG C is 5-16 min, and the O2 permeability coefficient of the modified copolyester is 0.003-0.015 cm < 3 >. Cm / cm < 2 >. S.Pa. The method comprises the following steps: (1) mixing boron nitride, a dispersing agent and a solvent to obtain a boron nitride suspension with a boron nitride particle size D50 of 10-1000nm and D90 of less than or equal to 2.5 D50; (2) under an esterification reaction condition, mixing a binary acid monomer, a dihydric alcohol monomer, the boron nitride suspension and a catalyst, and carrying out a first-stage reaction to obtain a prepolymer; (3) carrying out second-stage reaction on the prepolymer under the condition of polycondensation reaction; on the basis of the theoretical yield of the modified copolyester, the dosage of the boron nitride suspension is 0.003-0.1 wt% in terms of boron nitride. The modified copolyester has better crystallization property and gas barrier property at the same time, can be quickly molded, and has better application in preparation of preservative films and / or preservative bottles.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of polyesters, in particular, to a modified copolyester and a preparation method and application thereof. BACKGROUND

[0002] Polyethylene furanoate (PEF) belongs to bio-based polyester, which is a kind of polymer polyester material synthesized by biomass resources. It has great potential in replacing petroleum-based polyester-polyethylene terephthalate (PET) in application. Compared with PET material, PEF has higher mechanical strength, gas barrier performance and other excellent characteristics, and its melting point is about 215℃, which has lower processing conditions.

[0003] PEF polyester has furan five-membered ring structure, and the raw material generally used for synthesizing PEF is 2,5-furan dicarboxylic acid (FDCA) or its derivative 2,5-furan dicarboxylic acid dimethyl ester (DMFD). And 2,5-furan dicarboxylic acid (FDCA) or its derivative 2,5-furan dicarboxylic acid dimethyl ester (DMFD) is a meta monomer, which has weak symmetry and large molecular bond dipole interaction. Therefore, PEF has large resistance and slow crystallization in the crystallization process, which is not conducive to the setting process in the molding process. If the crystallization performance is not improved technically, the products such as fibers, films and bottles prepared from the material are prone to heat shrinkage and deformation.

[0004] In order to improve the crystallization performance of bio-based polyester, CN107216619A uses PEF and polyether PEG to improve the crystallization rate of PEF by blending, but too much flexible chain can easily lead to the decrease of gas barrier property of PEF; CN107118521A uses talc, sodium carbonate, silicon dioxide, isosorbide, sodium benzoate, N,N'-ethylene bis lauryl amide and ionomer of ethylene-methacrylic acid as nucleating agent to increase the nucleation site of PEF, reduce the nucleation induction period and accelerate the crystallization rate; Nadia Lotti et al. added multi-walled carbon nanotubes (MWCNTs), carboxyl modified multi-walled carbon nanotubes (MWCNTs-COOH), amino modified multi-walled carbon nanotubes (MWCNTs-NH2) and graphene oxide (GO) in PEF, which improved the crystallization performance of PEF to some extent, but the gas barrier performance could not be guaranteed, which affected the subsequent application of polyester material.

[0005] Therefore, it is urgent to provide a polyester material with both gas barrier performance and crystallization performance. SUMMARY

[0006] The application aims to overcome the problem that the crystallization performance and gas barrier property of PEE material cannot be compatible in the prior art, and provides a modified copolyester, a preparation method and application thereof, which can have good crystallization performance and gas barrier property, can be quickly formed, and has good application in preparation of packaging film and / or packaging bottle.

[0007] To achieve the above-mentioned object, the first aspect of the application provides a modified copolyester, wherein the semi-crystallization time of the modified copolyester at 170℃ is 5-16 min, the O2 permeation coefficient of the modified copolyester is 0.003-0.015 cm 3 ·cm / cm 2 ·s·Pa.

[0008] The second aspect of the application provides a preparation method of the modified copolyester, which comprises the following steps:

[0009] (1) mixing boron nitride, a dispersing agent and a solvent to obtain a boron nitride suspension with a particle size D 50 =10-1000nm, D 90 ≤2.5D 50 of the boron nitride;

[0010] (2) mixing a dibasic acid monomer, a dibasic alcohol monomer, the boron nitride suspension and a catalyst under esterification reaction conditions to perform a first-stage reaction to obtain a prepolymer;

[0011] (3) performing a second-stage reaction on the prepolymer under polycondensation reaction conditions;

[0012] The amount of the boron nitride suspension is 0.003-0.1 wt% based on the theoretical yield of the modified copolyester.

[0013] The third aspect of the application provides application of the modified copolyester of the first aspect and / or the modified copolyester prepared by the preparation method of the second aspect in a preservative film and / or a preservative bottle.

[0014] Through the above technical solution, the modified copolyester provided by the application has low semi-crystallization time and low O2 permeation coefficient, has good crystallization performance and good gas barrier property, can be quickly formed, and has good application in preparation of packaging film and / or packaging bottle.

[0015] The preparation method of the modified copolyester provided by the application mixes boron nitride to obtain a boron nitride suspension with a particle size D 50 =10-1000nm, D 90 ≤2.5D 50The boron nitride suspension is added to the preparation process of the polyester in a specific mass, which can effectively improve the crystallization performance and gas barrier performance of the copolyester, effectively reduce the use amount of boron nitride, reduce the cost, reduce the content of boron nitride impurities in the prepared polyester, quickly form, and has good application in the preparation of packaging film and / or packaging bottle. DETAILED DESCRIPTION

[0016] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not considered critical for the purposes of the application. The ranges and values are approximations that are intended to convey the significance of the ranges. Any numerical values are approximations that are not to be construed as limiting. The ranges and values are approximations that are intended to convey the significance of the ranges. Any numerical values are approximations that are not to be construed as limiting.

[0017] As described above, the first aspect of the application provides a modified copolyester, wherein the modified copolyester has a half crystallization time of 5-16 min at 170℃, and the modified copolyester has an O2 permeability coefficient of 0.003-0.015 cm 3 ·cm / cm 2 ·s·Pa.

[0018] The modified copolyester provided by the application has a lower half crystallization time and a lower O2 permeability coefficient, which indicates that it has better crystallization performance and better gas barrier performance. The modified copolyester provided by the application has better crystallization performance and better gas barrier performance, can be quickly formed, and has good application in the preparation of packaging film and / or packaging bottle

[0019] According to the application, the test method of the half crystallization time of the modified copolyester is that the polyester is isothermally crystallized at 170℃ for 30 min after eliminating the thermal history by DSC, and the half crystallization time t 1 / 2 at 170℃ is calculated by using the Avrami formula. The permeability coefficient of the modified copolyester is obtained according to the standard GB / T1038-2000. The half crystallization time of the modified copolyester at 170℃ can be 5 min, 7 min, 9 min, 11 min, 13 min, 15 min, 16 min, or any value in the range between any two of these values. The O2 permeability coefficient of the modified copolyester can be 0.003 cm 3 ·cm / cm 2 ·s·Pa, 0.005 cm 3 ·cm / cm 2 ·s·Pa, 0.007 cm 3 ·cm / cm 2 ·s·Pa, 0.009 cm 3 ·cm / cm2 s*Pa, 0.011 cm 3 cm / cm 2 s*Pa, 0.013 cm 3 cm / cm 2 s*Pa, 0.015 cm 3 cm / cm 2 s*Pa, or any value within a range defined by any two of these values.

[0020] Preferably, the modified copolyester has a half crystallization time at a temperature of 170°C of 5-10 min. The modified copolyester has a smaller half crystallization time at 170°C and can be quickly formed and is convenient to process.

[0021] Preferably, the O2permeability coefficient is 0.003-0.005 cm 3 cm / cm 2 s*Pa. The modified copolyester has better gas barrier properties.

[0022] Preferably, the modified copolyester has a CO2permeability coefficient of 0.003-0.015 cm 3 cm / cm 2 s*Pa, which can be 0.003 cm 3 cm / cm 2 s*Pa, 0.005 cm 3 cm / cm 2 s*Pa, 0.007 cm 3 cm / cm 2 s*Pa, 0.009 cm 3 cm / cm 2 s*Pa, 0.011 cm 3 cm / cm 2 s*Pa, 0.012 cm 3 cm / cm 2 s*Pa, 0.014 cm 3 cm / cm 2 s*Pa, 0.015 cm 3 cm / cm 2 s*Pa, or any value within a range defined by any two of these values. The modified copolyester has better gas barrier properties and has better application in packaging films and / or packaging bottles. Further preferably, the modified copolyester has a CO2permeability coefficient of 0.003-0.007 cm 3 cm / cm 2 s*Pa.

[0023] Preferably, the intrinsic viscosity of the modified copolyester is 0.6-0.9 dL / g, facilitating subsequent processing and molding.

[0024] According to the present application, the intrinsic viscosity of the modified copolyester is measured according to the test method described in GB / T14190-2017, and the solvent used in the test is phenol / tetrachloroethane with a mass ratio of 3:2.

[0025] Preferably, the modified copolyester contains boron nitride, and the content of the boron nitride in the modified copolyester is 0.003-0.1 wt%. The presence of the boron nitride in the modified copolyester in the above content can effectively improve the crystallization performance and gas barrier performance of the modified copolyester.

[0026] According to the present application, the content of the boron nitride in the modified copolyester can be 0.003 wt%, 0.02 wt%, 0.04 wt%, 0.06 wt%, 0.08 wt%, 0.1 wt%, or any value within the range between any two of these values. Further preferably, the content of the boron nitride in the modified copolyester is 0.01-0.1 wt% in consideration of further improving the crystallization performance and gas barrier performance of the modified copolyester.

[0027] According to the present application, the content of the boron nitride in the modified copolyester can be measured by measuring the content of boron in the modified copolyester, and the content of boron in the modified copolyester can be measured by elemental analysis.

[0028] Preferably, the modified copolyester further contains structural unit A represented by formula (I) and structural unit B represented by formula (II);

[0029]

[0030] wherein R1 and R2 are each independently C1-C4 alkyl or hydrogen; and R3 is C2-C4 alkylene. The inventors have found in the course of their research that the crystallization performance and gas barrier performance of the copolyester can be further improved by the interaction between structural unit A represented by formula (I), structural unit B represented by formula (II), and the boron nitride in the specific content. Further preferably, R1 and R2 are each independently hydrogen or methyl in consideration of further improving the crystallization performance and gas barrier performance of the modified copolyester.

[0031] According to the present application, the C1-C4 alkyl can be a linear alkyl without branches, a linear alkyl with branches, or a cyclic alkyl, and is preferably a linear alkyl without branches or a linear alkyl with branches. Specifically, it can be methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl, or 1,1-dimethylethyl.

[0032] The C2-C4 alkylene group can be a branched chain alkylene group or an unbranched chain alkylene group, and specifically can be ethylene, propylene, 1-methylethylene, butylene, 1-methylpropylene, 1,2-dimethylethylene, 1,1-dimethylisopropylene or 1-ethylethylene.

[0033] According to the present application, the content of the structural unit A and the structural unit B can be determined by infrared, nuclear magnetic resonance and the like.

[0034] Preferably, in the modified copolyester, the content of the structural unit A is 58-68 wt%, and further preferably 62-68 wt%, and the content of the structural unit B is 32-42 wt%, and further preferably 32-38 wt%. Limiting the content of the structural unit A and the content of the structural unit B in the modified copolyester to the above range can further improve the crystallization performance and gas barrier performance of the modified copolyester.

[0035] According to the present application, the content of the structural unit A and the structural unit B can be determined by infrared, nuclear magnetic resonance and the like. 1 HNMR nuclear magnetic resonance hydrogen spectrum measurement.

[0036] Preferably, the modified copolyester further contains antimony element. The presence of antimony element can further improve the crystallization performance and gas barrier performance of the modified copolyester. In order to further improve the crystallization performance and gas barrier performance of the modified copolyester, further preferably, the content of the antimony element in the modified copolyester is 200-600 ppm.

[0037] According to the present application, the antimony element in the modified copolyester and the content of the antimony element can be tested by elemental analysis.

[0038] The second aspect of the present application provides a preparation method of a modified copolyester, which comprises the following steps:

[0039] (1) mixing boron nitride, a dispersing agent and a solvent to obtain a boron nitride suspension with a particle size D 50 = 10-1000 nm, D 90 ≤ 2.5D 50 of boron nitride;

[0040] (2) mixing a dibasic acid monomer, a dibasic alcohol monomer, the boron nitride suspension and a catalyst under esterification reaction conditions to perform a first stage reaction to obtain a prepolymer;

[0041] (3) performing a second stage reaction on the prepolymer under polycondensation reaction conditions;

[0042] The amount of the boron nitride suspension, calculated as boron nitride, is 0.003-0.1 wt% based on the theoretical yield of the modified copolyester.

[0043] In the above preparation method, the particle size D 50 = 10-1000 nm, D 90 ≤ 2.5D 50 of the boron nitride suspension is added to the preparation process of the polyester, and the addition amount of the boron nitride suspension is 0.003-0.1 wt% of the theoretical output of the modified copolyester based on boron nitride, which can effectively improve the crystallization performance and gas barrier performance of the copolyester, effectively reduce the amount of boron nitride, reduce the content of boron nitride impurities in the prepared polyester, quickly form, and has good application in the preparation of packaging film and / or packaging bottle.

[0044] According to the present application, the test method of the particle size of boron nitride can use the dynamic light scattering Zetasizer Nano ZS particle analyzer produced by Malvern Company. D 10 , D 50 and D 90 respectively represent the particle size corresponding to the cumulative particle size distribution number of 10%, 50% and 90% of the sample (manually add the percentage of all particle sizes before or after the particle size); its physical meaning means that the number of particles with a particle size less than the particle size accounts for 10%, 50% and 90% of the total number of particles.

[0045] The particle size D 50 of the boron nitride can be 10 nm, 200 nm, 400 nm, 600 nm, 800 nm, 1000 nm, or any value within the range between any two of these values.

[0046] Preferably, the particle size D 90 of the boron nitride is ≤ 2D 50 , which can further improve the crystallization performance and gas barrier performance of the prepared copolyester.

[0047] Preferably, the particle size D 10 of the boron nitride in the boron nitride suspension is = 4-500 nm, D 90 = 15-2000 nm. Controlling the boron nitride suspension under the above conditions can further improve the crystallization performance and gas barrier performance of the prepared modified copolyester. Further preferably, in the boron nitride suspension, the particle size D 10 of the boron nitride is = 20-250 nm, D 50 = 50-500 nm, D 90 = 85-765 nm, more preferably, D 10 ≥ D 50The absolute value of the Zeta potential of the boron nitride is 30-45 mV.

[0048] According to the present application, the particle size D 10 may be 4 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 400 nm, or any value within a range consisting of any two of these values. The particle size D 90 may be 15 nm, 200 nm, 400 nm, 600 nm, 800 nm, 1000 nm, 1200 nm, 1400 nm, 1600 nm, 1800 nm, 2000 nm, or any value within a range consisting of any two of these values. The absolute value of the Zeta potential of the boron nitride can be 30 mV, 35 mV, 40 mV, 45 mV, or any value within a range consisting of any two of these values.

[0049] The absolute value of the Zeta potential of the boron nitride is measured by a dynamic light scattering Zetasizer Nano ZS particle analyzer produced by Malvern.

[0050] Preferably, the amount of the boron nitride suspension is 0.01-0.1 wt% based on the theoretical yield of the modified copolyester.

[0051] According to the present application, the mixing of the boron nitride, the dispersant and the solvent can be performed in any feasible manner, which can be stirring mixing, can be shaking mixing, or can be ultrasonic mixing. In a specific embodiment of the present application, the mixing is stirring mixing, and the mixing conditions include at least a rotation speed of 500-800 rpm, which can be specifically 500 rpm, 600 rpm, 700 rpm, 800 rpm, or any value within a range consisting of any two of these values. Controlling the mixing conditions within the above range can make the prepared boron nitride suspension have a better dispersion effect in the polyester, thereby effectively improving the crystallization performance and the gas barrier performance of the copolyester.

[0052] Preferably, the concentration of the boron nitride in the boron nitride suspension is 5-20 wt%. The boron nitride suspension prepared under this condition is used for the preparation of the polyester, and the prepared polyester has a better crystallization performance and a better gas barrier performance.

[0053] Preferably, in step (1), the dispersant is a trimeric phosphate and / or a hexametaphosphate. The use of trimeric phosphate and / or hexametaphosphate as the dispersant can further improve the crystallization performance and gas barrier performance of the modified copolyester. The dispersant can be selected from at least one of potassium trimeric phosphate, sodium trimeric phosphate, potassium hexametaphosphate and sodium hexametaphosphate. In order to further improve the crystallization performance and gas barrier performance of the modified copolyester, it is further preferred that the dispersant is sodium trimeric phosphate and / or sodium hexametaphosphate, and more preferably sodium trimeric phosphate and sodium hexametaphosphate. As a relatively preferred embodiment of the present application, the mass ratio of sodium trimeric phosphate to sodium hexametaphosphate is 1:0.8-1.2.

[0054] Preferably, the solvent is selected from at least one of ethylene glycol, propylene glycol and butylene glycol. It is further preferred that the solvent is consistent with the dihydric alcohol monomer in step (2), which can improve the dispersion effect while not introducing new impurities.

[0055] Preferably, in step (1), the method further comprises ball milling the mixed solution obtained by mixing. It is further preferred that the method further comprises centrifugal treatment of the mixed solution obtained by ball milling. It is further preferred that the centrifugal treatment is performed under conditions including a rotation speed of 1000-3000 rpm. The time for the above-mentioned ball milling and centrifugal treatment is not particularly limited, as long as it can make the boron nitride suspended particles in the boron nitride suspension have a particle size D 50 =10-1000nm and a Zeta potential absolute value of 30-50mV.

[0056] Preferably, the dihydric acid monomer contains a dihydric acid having a structure shown in formula (I), and the dihydric alcohol monomer contains a dihydric alcohol having a structure shown in formula (II);

[0057]

[0058] wherein R1and R2are each independently C1-C4alkyl or hydrogen; and R3is C2-C4alkylene. The inventors have found in the research process that the interaction between the dihydric acid residue having the structure shown in formula (I), the dihydric alcohol residue having the structure shown in formula (II) and the ball-milled boron nitride can further improve the crystallization performance and gas barrier performance of the copolyester. In order to further improve the crystallization performance and gas barrier performance of the modified copolyester, it is further preferred that R1and R2are each independently hydrogen or methyl.

[0059] According to the present application, the C1-C4 alkyl group can be a linear alkyl group without branch, a linear alkyl group with branch, or a cyclic alkyl group, preferably a linear alkyl group without branch or a linear alkyl group with branch. Specifically, it can be methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl or 1,1-dimethylethyl.

[0060] The C2-C4 alkylene group can be a linear alkylene group with branch or a linear alkylene group without branch, specifically ethylene, propylene, 1-methylethylene, butylene, 1-methylpropylene, 1,2-dimethylethylene, 1,1-dimethylisopropylene or 1-ethylethylene.

[0061] Preferably, the catalyst is an antimony-based catalyst. With the above-mentioned antimony-based catalyst, the reaction effect of the diacid and the diol can be improved, and the dispersion effect of the boron nitride in the polyester can also be improved, so that the crystallization property and the gas barrier property of the prepared copolyester can be further improved. In order to further improve the crystallization property and the gas barrier property of the prepared copolyester, it is further preferred that the catalyst is selected from at least one of antimony oxide, antimony acetate and ethylene glycol antimony. More preferably, the amount of the catalyst in terms of the element antimony is 200-600 ppm based on the theoretical yield of the modified copolyester.

[0062] Preferably, in step (2), the esterification reaction conditions at least include: the temperature is 180-220℃, which can be 180℃, 190℃, 200℃, 210℃, 220℃, or any value within the range composed of any two of these values; the pressure is ≤0.4 MPa. Under the above conditions, the diacid unit and the diol unit have good esterification effect, thereby effectively improving the gas barrier property of the prepared copolyester.

[0063] Preferably, in step (3), the polycondensation reaction conditions at least include: the temperature is 235-255℃, which can be 235℃, 240℃, 245℃, 250℃, 255℃, or any value within the range composed of any two of these values; the pressure is ≤50 Pa. Under the above conditions, the esterification reaction product has good polycondensation effect, thereby effectively improving the gas barrier property of the prepared copolyester.

[0064] Preferably, the molar ratio between the diacid and the diol is 1:1.1-1.5, and further preferably 1:1.1-1.2.

[0065] The third aspect of the present application provides an application of the modified copolyester of the first aspect or the modified copolyester prepared by the preparation method of the second aspect in a preservative film and / or a preservative bottle.

[0066] The modified copolyester has good gas barrier property and crystallization property, can facilitate the rapid forming of the preservative film and / or the preservative bottle, and has good preservative effect.

[0067] According to a particularly preferred embodiment of the present application, a preparation method of the modified copolyester is provided, which comprises the following steps:

[0068] (1) dissolving the dispersant in part of the solvent to obtain a solution containing the dispersant, mixing the solution containing the dispersant, boron nitride and the remaining solvent at a rotation speed of 500-800 rpm, and then ball milling the mixed solution to obtain a boron nitride suspension with a particle size D 10 = 4-500 nm, D 50 = 10-1000 nm, D 90 = 15-2000 nm, D 90 ≤ 2D 50 , D 10 ≥ D 50 / 2 and a Zeta potential absolute value of 40-45 mV;

[0069] (2) performing a first stage reaction on the dibasic acid monomer, the dibasic alcohol monomer, the boron nitride suspension and the catalyst under the condition of a temperature of 220-260 ℃ and a pressure less than or equal to 0.4 MPa to obtain a prepolymer;

[0070] (3) performing a second stage reaction on the prepolymer under the condition of a temperature of 260-280 ℃ and a pressure of ≤50 Pa;

[0071] The dibasic acid monomer contains a dibasic acid having a structure shown in formula (I), and the dibasic alcohol monomer contains a dibasic alcohol having a structure shown in formula (II);

[0072]

[0073] wherein R1 and R2 are each independently C1-C4 alkyl or hydrogen; R3 is C2-C4 alkylene; the dispersant is sodium tripolyphosphate and / or sodium hexametaphosphate, the solvent corresponds to the dibasic alcohol monomer, and the catalyst is selected from at least one of antimony oxide, antimony acetate and ethylene glycol antimony; and the amount of the catalyst is 200-600 ppm based on the theoretical yield of the modified copolyester.

[0074] The modified copolyester prepared by the above method has a low semi-crystallization time, and the semi-crystallization time t 1 / 2 is reduced by more than 75%, can be rapidly formed, has a low oxygen permeation coefficient and carbon dioxide permeation coefficient, and the O2 and CO2 permeation coefficients are reduced by more than 20%, and has a good gas barrier effect.

[0075] The present application will be described in detail below by way of examples. In the following examples, h-BNNS (hexagonal boron nitride nanosheet) was purchased from DENKA Co., Ltd., product number SP-2; spherical boron nitride was purchased from DENKA Co., Ltd., with a median particle size of 0.5 μm and an average circularity of 0.8; and needle-shaped boron nitride was prepared according to the method described in JP 60151202A.

[0076] Particle size: The prepared h-BNNS / EG suspension was tested using a dynamic light scattering Zetasizer Nano ZS particle analyzer produced by Malvern Co., Ltd.

[0077] Zeta potential: The prepared h-BNNS / EG suspension was tested using a dynamic light scattering Zetasizer Nano ZS particle analyzer produced by Malvern Co., Ltd.

[0078] Semi-crystallization time t 1 / 2 : The bio-based polyester was isothermally crystallized at 170°C for 30 min after DSC heat history elimination, and the semi-crystallization time t at 170°C isothermally crystallized was calculated using the Avrami formula 1 / 2 .

[0079] Gas permeation coefficient: The gas barrier performance test standard GB / T 1038-2000 was used.

[0080] Example 1

[0081] (1) 120 g of h-BNNS was mixed with 880 g of ethylene glycol and 1 g of a 50% sodium tripolyphosphate / EG solution, pre-dispersed at a high speed of 500 rpm for 30 min, ball-milled at a feed flow rate of 100 g / min, and finally centrifuged at 2000 rpm by a horizontal centrifuge to obtain a suspension containing 12 wt% h-BNNS concentration with a particle size D 50 of 100 nm, D 10 of 57 nm, D 90 of 189 nm, and a Zeta potential absolute value of 45 mV.

[0082] (2) 5000 g of 2,5-FDCA, 3000 g of ethylene glycol, 3.44 g of ethylene glycol antimony catalyst, and 4.86 g of the above h-BNNS / EG suspension were added to a 20 L polymerization reactor, and the first stage reaction was carried out at a temperature of 180°C and a pressure of less than or equal to 0.4 MPa to obtain a prepolymer.

[0083] (3) The prepolymer was subjected to a second stage reaction at a temperature of 240°C and a pressure of ≤ 50 Pa to obtain PEF with an intrinsic viscosity of 0.6 dL / g and an effective content of h-BNNS of 0.01%.

[0084] Example 2

[0085] PET was prepared according to the method described in Example 1, except that in step (2), the amount of h-BNNS / EG suspension added was 1.46 g.

[0086] Example 3

[0087] PET was prepared according to the method described in Example 1, except that in step (2), the amount of h-BNNS / EG suspension added was 3.4 g.

[0088] Example 4

[0089] PET was prepared according to the method described in Example 1, except that in step (2), the amount of h-BNNS / EG suspension added was 14.58 g.

[0090] Example 5

[0091] PET was prepared according to the method described in Example 1, except that in step (2), the amount of h-BNNS / EG suspension added was 24.3 g.

[0092] Example 6

[0093] PET was prepared according to the method described in Example 1, except that in step (2), the amount of h-BNNS / EG suspension added was 34.02 g.

[0094] Example 7

[0095] PET was prepared according to the method described in Example 1, except that in step (2), the amount of h-BNNS / EG suspension added was 48.6 g.

[0096] Example 8

[0097] PET was prepared according to the method described in Example 1, except that step (1) included mixing 120 g of h-BNNS with 880 g of ethylene glycol, 1 g of a 50% sodium tripolyphosphate / EG solution, pre-dispersing for 60 min with high-speed stirring at 500 rpm, ball-milling with a feed rate of 10 g / min, and finally obtaining a suspension containing 12 wt% h-BNNS concentration with a particle size D 50 of 10 nm, D 10 of 4 nm, D 90 of 19 nm, and a Zeta potential absolute value of 31 mV.

[0098] Example 9

[0099] PET was prepared according to the method described in Example 1, except that step (1) included mixing 120 g h-BNNS with 880 g ethylene glycol, 1 g of a 50% sodium tripolyphosphate / EG solution, pre-dispersing for 30 min with high speed stirring at 500 rpm, ball milling with a feed rate of 50 g / min, and finally obtaining a suspension containing a concentration of 12 wt% h-BNNS with a particle size D 50 of 50 nm, D 10 of 21 nm, D 90 of 85 nm, and a Zeta potential absolute value of 41 mV.

[0100] Example 10

[0101] PET was prepared according to the method described in Example 1, except that step (1) included mixing 120 g h-BNNS with 880 g ethylene glycol, 1 g of a 50% sodium tripolyphosphate / EG solution, pre-dispersing for 30 min with high speed stirring at 500 rpm, ball milling with a feed rate of 500 g / min, and finally obtaining a suspension containing a concentration of 12 wt% h-BNNS with a particle size D 50 of 500 nm, D 10 of 233 nm, D 90 of 763 nm, and a Zeta potential absolute value of 44 mV.

[0102] Example 11

[0103] PET was prepared according to the method described in Example 1, except that step (1) included mixing 120 g h-BNNS with 880 g ethylene glycol, 1 g of a 50% sodium tripolyphosphate / EG solution, pre-dispersing for 30 min with high speed stirring at 500 rpm, ball milling with a feed rate of 1000 g / min, and finally obtaining a suspension containing a concentration of 12 wt% h-BNNS with a particle size D 50 of 1000 nm, D 10 of 486 nm, D 90 of 1924 nm, and a Zeta potential absolute value of 38 mV.

[0104] Example 12

[0105] PET was prepared according to the method described in Example 1, except that the 50% sodium tripolyphosphate / EG solution was replaced with a 50% sodium hexametaphosphate / EG solution, and finally obtaining a suspension containing a concentration of 12 wt% h-BNNS with a particle size D 50 of 100 nm, D 10 of 55 nm, D 90having a concentration of 12wt% h-BNNS with a particle size D

[0106] Example 13

[0107] PET was prepared according to the method described in Example 1, except that in step (1), h-BNNS was replaced by spherical boron nitride to obtain a particle size D 50 of 100 nm, D 10 of 67 nm, D 90 having a concentration of 12wt% h-BNNS with a particle size D

[0108] Example 14

[0109] PET was prepared according to the method described in Example 1, except that in step (1), h-BNNS was replaced by needle-shaped boron nitride to obtain a particle size D 50 of 100 nm, D 10 of 51 nm, D 90 having a concentration of 12wt% h-BNNS with a particle size D

[0110] Example 15

[0111] (1) 120g h-BNNS was mixed with 880g ethylene glycol, 1g 50% sodium tripolyphosphate / EG solution, pre-dispersed for 30min under high-speed stirring at 500rpm, ball-milled at a feed rate of 100g / min, and finally centrifuged by a horizontal centrifuge at 2000rpm to obtain a particle size D 50 of 100 nm, D 10 of 57 nm, D 90 having a concentration of 12wt% h-BNNS with a particle size D

[0112] (2) 5000g of 2,5-FDCA, 2800g of ethylene glycol, 4.89g of ethylene glycol antimony catalyst and 4.86g of the above h-BNNS / EG suspension were added to a 20L polymerization reactor, and the first stage reaction was carried out at a temperature of 200°C and a pressure less than or equal to 0.4MPa to obtain a prepolymer.

[0113] (3) The prepolymer was subjected to a second stage reaction at a temperature of 235°C and a pressure of ≤50Pa to obtain PEF with an intrinsic viscosity of 0.6dL / g and an effective content of h-BNNS of 0.01%.

[0114] Example 16

[0115] (1) 120 g h-BNNS was mixed with 880 g ethylene glycol, 1 g 50% sodium tripolyphosphate / EG solution, pH was adjusted to 7.5 by pH adjuster, pre-dispersed for 30 min under high speed stirring at 500 rpm, ball-milled at a feeding rate of 100 g / min, and finally obtained a suspension containing 12 wt% h-BNNS concentration with a particle size D 50 of 100 nm, D 10 of 57 nm, D 90 of 189 nm, and Zeta potential absolute value of 45 mV.

[0116] (2) 5000 g of 2,5-FDCA, 3500 g of ethylene glycol, 6 g of ethylene glycol antimony catalyst, and 4.86 g of the above h-BNNS / EG suspension were added into a 20 L polymerization reactor, and a prepolymer was obtained by first stage reaction at a temperature of 220 °C and a pressure less than or equal to 0.4 MPa.

[0117] (3) The prepolymer was subjected to second stage reaction at a temperature of 245 °C and a pressure less than or equal to 50 Pa, and the obtained PEF had an intrinsic viscosity of 0.6 dL / g and an effective content of h-BNNS of 0.01%.

[0118] Example 17

[0119] (1) 120 g h-BNNS was mixed with 880 g ethylene glycol, 1 g 50% sodium tripolyphosphate / EG solution, pH was adjusted to 7.5 by pH adjuster, pre-dispersed for 30 min under high speed stirring at 500 rpm, ball-milled at a feeding rate of 100 g / min, and finally obtained a suspension containing 12 wt% h-BNNS concentration with a particle size D 50 of 100 nm, D 10 of 57 nm, D 90 of 189 nm, and Zeta potential absolute value of 45 mV.

[0120] (2) 5000 g of 2,5-FDCA, 3200 g of propylene glycol, 3.44 g of antimony acetate catalyst, and 4.86 g of the above h-BNNS / EG suspension were added into a 20 L polymerization reactor, and a prepolymer was obtained by first stage reaction at a temperature of 180 °C and a pressure less than or equal to 0.4 MPa.

[0121] (3) The prepolymer was subjected to second stage reaction at a temperature of 240 °C and a pressure less than or equal to 50 Pa, and the obtained PEF had an intrinsic viscosity of 0.6 dL / g and an effective content of h-BNNS of 0.01%.

[0122] Comparative Example 1

[0123] (1) In a 20L polymerization reactor, 5000g of 2,5-FDCA, 3000g of ethylene glycol and 3.44g of ethylene glycol antimony catalyst were added, and the first stage reaction was carried out at a temperature of 180°C and a pressure of less than or equal to 0.4MPa to obtain a prepolymer.

[0124] (2) The prepolymer was subjected to a second stage reaction at a temperature of 240°C and a pressure of less than or equal to 50Pa to obtain PEF with an intrinsic viscosity of 0.6dL / g.

[0125] Comparative Example 2

[0126] PEF was prepared according to the method described in Example 1, except that in step (2), the amount of h-BNNS / EG suspension added was 72.9g.

[0127] Comparative Example 3

[0128] PEF was prepared according to the method described in Example 1, except that step (1) included: 120g of h-BNNS was mixed with 880g of ethylene glycol, 1g of 50% sodium tripolyphosphate / EG solution, the pH was adjusted to 7.5 by a pH adjuster, and pre-dispersed for 30min under high-speed stirring at 500rpm, ball-milled at a feed flow rate of 1500g / min, and finally obtained a suspension containing 12wt% h-BNNS concentration with a particle size D 50 of 1500nm, D 10 of 723nm, D 90 of 3011nm, and a Zeta potential absolute value of 45mV.

[0129] Comparative Example 4

[0130] PEF was prepared according to the method described in Example 1, except that step (1) included: 120g of h-BNNS was mixed with 880g of ethylene glycol, the pH was adjusted to 7.5 by a pH adjuster, and pre-dispersed for 30min under high-speed stirring at 500rpm, ball-milled at a feed flow rate of 100g / min, and finally obtained a suspension containing 12wt% h-BNNS concentration with a particle size D 50 of 100nm, D 10 of 61nm, D 90 of 316nm, and a Zeta potential absolute value of 21mV.

[0131] Comparative Example 5

[0132] PEF was prepared according to the method described in Example 1 except that step (1) comprised mixing 120 g h-BNNS with 880 g ethylene glycol, 1 g of a 50% sodium tripolyphosphate / EG solution, adjusting the pH to 7.5 with a pH adjuster, pre-dispersing for 30 min with high speed stirring at 500 rpm, and ball milling with a feed flow of 100 g / min, and finally obtaining a suspension with a particle size D 50 of 100 nm, a D 10 of 45 nm, a D 90 of 715 nm, and a Zeta potential absolute value of 11 mV, containing a concentration of 12 wt% h-BNNS.

[0133] Comparative Example 6

[0134] PEF was prepared according to the method described in Example 1 except that step (1) comprised mixing 120 g h-BNNS with 880 g ethylene glycol, 1 g of a 50% sodium tripolyphosphate / EG solution, adjusting the pH to 7.5 with a pH adjuster, pre-dispersing for 30 min with high speed stirring at 500 rpm, and ball milling with a feed flow of 100 g / min, and finally obtaining a suspension with a particle size D 50 of 100 nm, a D 10 of 41 nm, a D 90 of 957 nm, and a Zeta potential absolute value of 15 mV, containing a concentration of 12 wt% h-BNNS.

[0135] Comparative Example 7

[0136] PEF was prepared according to the method described in Example 17 except that in step (2) the h-BNNS / EG suspension was added in an amount of 72.9 g.

[0137] Comparative Example 8

[0138] PEF was prepared according to the method described in Example 17 except that step (1) comprised mixing 120 g h-BNNS with 880 g ethylene glycol, 1 g of a 50% sodium tripolyphosphate / EG solution, adjusting the pH to 7.5 with a pH adjuster, pre-dispersing for 30 min with high speed stirring at 500 rpm, ball milling with a feed flow of 1500 g / min, and finally obtaining a suspension with a particle size D 50 of 1500 nm, a D 10 of 723 nm, a D 90 of 3011 nm, and a Zeta potential absolute value of 45 mV, containing a concentration of 12 wt% h-BNNS.

[0139] Comparative Example 9

[0140] The PEF was prepared according to the method described in Example 17, except that step (1) included mixing 120 g h-BNNS with 880 g ethylene glycol, adjusting the pH to 7.5 by a pH regulator, pre-dispersing for 30 min under high-speed stirring at 500 rpm, ball-milling at a feeding flow rate of 100 g / min, and finally centrifuging by a horizontal centrifuge at 2000 rpm, to obtain a suspension containing 12 wt% h-BNNS with a particle size D 50 100 nm, D 10 61 nm, D 90 316 nm, and a zeta potential absolute value of 21 mV.

[0141] Table 1: Content of h-BNNS in the polyester, content of structural units, and physical and chemical parameters of the h-BNNS used

[0142]

[0143]

[0144] Table 2: Performance parameters of the polyesters

[0145]

[0146]

[0147] As can be seen from the above table, compared with the conventional PEF polyester (Comparative Example 1), the addition of h-BNNS in the examples can effectively improve the crystallization rate, and the gas barrier property is also improved, especially in Example 1, the gas barrier property is improved by more than 60%. The h-BNNS addition content is 0.003%-0.1%, of which 0.01% is preferred; when the addition content exceeds 0.1% (Comparative Examples 2 and 7), the crystallization of the copolyester is hindered due to excessive addition content, and the molecular arrangement and crystallization are difficult, resulting in a slow crystallization rate. The median particle size of h-BNNS is in the range of 10 nm-1000 nm, of which 100 nm is preferred; when h-BNNS with a median particle size exceeding 1000 nm is used (Comparative Examples 3 and 8), the effect of the particles as nucleating agents is weakened due to the excessively large particle size, and the excessively large particles increase the resistance of molecular arrangement and crystallization, resulting in a slow crystallization rate. When the h-BNNS / EG suspension is not optimized for dispersion (Comparative Examples 4-6 and Comparative Example 9), the dispersion of the particles is poor, mainly manifested as a large number of abnormal agglomerated large particles, D 90 out of range, at this time, due to particle agglomeration, the improvement of the crystallization performance is limited, and the agglomerated particles no longer have the function of the original two-dimensional nanostructure, and the gas barrier property of the copolyester is hardly improved. The above shows that the polyester provided by the present application has good gas barrier property and crystallization performance.

[0148] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A modified copolyester, characterized in that, The modified copolyester has a semi-crystallization time of 5-16 minutes at 170°C, and its O2 permeability coefficient is 0.003-0.015 cm⁻¹. 3 ·cm / cm 2 ·s·Pa.

2. The modified copolyester according to claim 1, characterized in that, The modified copolyester has a CO2 permeability coefficient of 0.003-0.015 cm⁻¹. 3 ·cm / cm 2 •s·Pa, preferably 0.003-0.007cm 3 ·cm / cm 2 ·s·Pa.

3. The modified copolyester according to claim 1 or 2, wherein the semi-crystallization time of the modified copolyester at 170°C is 5-10 min; Preferably, the modified copolyester has an O2 permeability coefficient of 0.003-0.005 cm⁻¹. 3 ·cm / cm 2 ·s·Pa; Preferably, the intrinsic viscosity of the modified copolyester is 0.6-0.9 dL / g.

4. The modified copolyester according to claim 1 or 2, characterized in that, The modified copolyester contains boron nitride, and the content of boron nitride in the modified copolyester is 0.003-0.1 wt%, preferably 0.01-0.1 wt%. Preferably, the modified copolyester further comprises structural unit A as shown in formula (I) and structural unit B as shown in formula (II); Wherein, R1 and R2 are each independently C1-C4 alkyl or hydrogen, preferably hydrogen or methyl; R3 is C2-C4 alkylene; Preferably, in the modified copolyester, the content of structural unit A is 58-68 wt%, and the content of structural unit B is 32-42 wt%.

5. The modified copolyester according to claim 1 or 2, characterized in that, The modified copolyester also contains antimony. Preferably, the antimony content in the modified copolyester is 200-600 ppm.

6. A method for preparing a modified copolyester, characterized in that, The method includes the following steps: (1) After mixing boron nitride, dispersant and solvent, the boron nitride particle size D is obtained. 50 =10-1000nm, D 90 ≤2.5D 50 Boron nitride suspension; (2) Under esterification reaction conditions, the dicarboxylic acid monomer, the diol monomer, the boron nitride suspension and the catalyst are mixed to carry out the first stage reaction to obtain the prepolymer; (3) Under polycondensation reaction conditions, the prepolymer is subjected to a second-stage reaction; Based on the theoretical yield of the modified copolyester, the amount of the boron nitride suspension used, calculated as boron nitride, is 0.003-0.1 wt%.

7. The preparation method according to claim 6, characterized in that, In step (1), in the boron nitride suspension, the particle size D of the boron nitride is... 10 =4-500nm, D 90 =15-2000nm; Preferably, in the boron nitride suspension, the particle size D of the boron nitride is... 10 =20-250nm, D 50 =50-500nm, D 90 =85-765nm; Preferably, the particle size D of boron nitride 90 ≤2D 50 D 10 ≥D 50 / 2, the absolute value of the boron nitride zeta potential is 30-50mV; Preferably, the dispersant is tripolyphosphate and / or hexametaphosphate; Preferably, the solvent is selected from at least one of ethylene glycol, propylene glycol, and butanediol, and more preferably ethylene glycol; Preferably, the mixing conditions include at least: a rotational speed of 500-800 rpm; Preferably, in step (1), the method further includes: ball milling the mixture obtained by mixing; Preferably, the method further includes centrifuging the mixture obtained by ball milling.

8. The preparation method according to claim 6 or 7, characterized in that, The dicarboxylic acid monomer contains a dicarboxylic acid having the structure shown in formula (I), and the diol monomer contains a diol having the structure shown in formula (II); Wherein, R1 and R2 are each independently C1-C4 alkyl or hydrogen, preferably hydrogen or methyl; R3 is C2-C4 alkylene; Preferably, based on the theoretical yield of the modified copolyester, the amount of the boron nitride suspension used, calculated as boron nitride, is 0.01-0.1 wt%. Preferably, the catalyst is an antimony-based catalyst, and more preferably at least one of antimony oxide, antimony acetate, and antimony glycolate; Preferably, the amount of catalyst used, calculated as antimony, is 200-600 ppm, based on the theoretical yield of the modified copolyester.

9. The preparation method according to claim 6 or 7, characterized in that, In step (2), the esterification reaction conditions include at least the following: a temperature of 180-220°C and a gauge pressure of less than or equal to 0.4 MPa; Preferably, in step (3), the polycondensation reaction conditions include at least the following: temperature of 235-255℃ and pressure ≤50Pa.

10. The use of the modified copolyester according to any one of claims 1 to 5 and / or the modified copolyester prepared by the preparation method according to any one of claims 6 to 9 in packaging films and / or packaging bottles; Preferably, the packaging film is a food preservation film, and the packaging bottle is a food preservation bottle and / or a pharmaceutical storage bottle.

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