A PETG resin, its preparation method and application

Abstract

This invention provides a PETG resin, its preparation method, and its applications. The PETG resin comprises segments formed by a dicarboxylic acid component and a straight-chain alkane diol component, as well as segments formed by a dicarboxylic acid component and a rigid diol component. The dicarboxylic acid component includes terephthalic acid, the straight-chain alkane diol component includes ethylene glycol and 1,4-cyclohexanediethanol, and the rigid diol component includes isosorbide. In the PETG resin, relative to the segments derived from terephthalic acid, the content of ethylene glycol segments is 80 mol% to 85 mol%, the content of 1,4-cyclohexanediethanol segments is 7 mol% to 10 mol%, and the content of isosorbide segments is 2 mol% to 4 mol%. The PETG resin of this invention can significantly improve isosorbide retention, improve resin color and transparency, while maintaining a low CHDM content, making it an easily recyclable PETG resin.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and relates to a PETG resin, its preparation method and application, and more particularly to an easily recyclable PETG resin with excellent color and high isosorbide retention rate, its preparation method and application. Background Technology

[0002] The cosmetic packaging market is enormous, and conventional polyethylene terephthalate (PET) is widely used in thin-walled cosmetic packaging due to its low price. However, PET's high crystallinity leads to poor transparency in molded products. 1,4-Cyclohexanediethanol (CHDM), with its boat-like structure, can improve PET's transparency, chemical resistance, and processability by introducing CHDM into it, thus compensating for PET's shortcomings in thick-walled cosmetic packaging. Currently, commercially available PETG contains approximately 30 mol% CHDM, which is costly and incompatible with existing PET recycling systems, failing to meet its application requirements in a sustainable development context. Reducing the CHDM content to meet the RIC1 resin definition in ASTM-D7611-20 can improve PETG's recyclability. However, when the CHDM content is below or equal to 12 mol%, the transparency of PETG decreases significantly, making it difficult to meet the appearance requirements of thick-walled cosmetic packaging.

[0003] Existing reports indicate that the transparency of PETG with low CHDM content can be improved by introducing bio-based rigid diols such as isosorbide (ISB) to replace part of CHDM as the fourth monomer. However, as a secondary alcohol, isosorbide has low reactivity in esterification reactions and is difficult to compete with primary alcohols for entry into the molecular chain. Conventional PET polyester synthesis conditions are insufficient to meet its copolymerization insertion requirements, resulting in a low retention rate of ISB in the final product. Furthermore, the ether bonds in the ISB molecule make it thermally unstable, prone to oxidation and decomposition under high-temperature esterification or acidic conditions, leading to problems such as deterioration of the final product's color value, severely impacting its application value. Patents CN112752785A and CN 116348526A, which use isosorbide in a "one-pot" method to prepare polyester copolymers, extend the vacuum reaction time at the end of the esterification or transesterification reaction or at the beginning of the polycondensation reaction to remove unreacted ISB from the system, due to the low retention rate of isosorbide, in order to ensure other product properties. Patent CN121343138 A discloses a transparent copolyester, its preparation method, and the products made from it. It also employs a one-pot process. To ensure other product properties, it extends the vacuum reaction time at the end of the esterification or transesterification reaction or at the beginning of the polycondensation reaction to remove unreacted ISB from the system. Patent CN 120665273 A discloses an isosorbide-based heat-resistant, yellowing-resistant, biodegradable polyester and its preparation method. It also employs a one-pot process and does not address the issues of low ISB retention and easy decomposition. Its color is achieved by introducing 1,1-cyclohexanedicarboxylic acid to partially replace terephthalic acid, a method that leads to a decrease in the resin's mechanical properties. CN 121537618 A discloses an isosorbide-based copolyester, its preparation method, and its application. The method employs a stepwise esterification process, first reacting ISB with an excess of aromatic dicarboxylic acid and an acylating agent to undergo a first esterification reaction. This allows the acylating agent to efficiently and specifically activate the secondary hydroxyl groups of ISB, improving the retention rate of ISB in the final polymer. However, this method, by first preparing the ISB ester, suffers from significant steric hindrance, hindering the esterification reactions of other diols. Furthermore, the method still exposes ISB to a prolonged high-temperature environment, leading to side reactions such as oxidation and decomposition. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a PETG resin, its preparation method, and its applications, particularly an easily recyclable PETG resin with excellent hue and high isosorbide retention, its preparation method, and its applications.

[0005] To achieve this objective, the present invention employs the following technical solution: On one hand, the present invention provides a PETG resin comprising segments formed of a dicarboxylic acid component and a straight-chain alkane diol component, and segments formed of a dicarboxylic acid component and a rigid diol component, wherein the dicarboxylic acid component comprises terephthalic acid, the straight-chain alkane diol component comprises ethylene glycol and / or 1,4-cyclohexanediethanol, and the rigid diol component comprises isosorbide. In the PETG resin, relative to the segments derived from terephthalic acid, the content of ethylene glycol segments is 80 mol% to 85 mol%, the content of 1,4-cyclohexanediethanol segments is 7 mol% to 10 mol%, and the content of isosorbide segments is 2 mol% to 4 mol.

[0006] The PETG resin of this invention is easy to recycle, has excellent color value, high isosorbide retention rate and excellent transparency, and can therefore be used in the preparation of thick-walled cosmetic bottles, and its waste products can participate in the PET recycling process.

[0007] In this invention, the ethylene glycol (EG) content is 105 mol% to 110 mol% relative to the terephthalic acid (TPA) content, the 1,4-cyclohexanediethanol (CHDM) content is 7.5 mol% to 10 mol% relative to the TPA content, and the isosorbide (ISB) content is 2.5 mol% to 5 mol% relative to the TPA content. The PETG resin contains 80 mol% to 85 mol% (e.g., 80 mol%, 81 mol%, 82 mol%, 83 mol%, 84 mol%, or 85 mol%) of ethylene glycol segments (EG-Final) relative to terephthalic acid segments (TPA-Final), 7 mol% to 10 mol% (e.g., 7 mol%, 7.3 mol%, 7.6 mol%, 7.9 mol%, 8.2 mol%, 8.5 mol%, 8.8 mol%, 9.1 mol%, 9.4 mol%, 9.7 mol%, or 10 mol%) of ethylene glycol segments (EG-Final) relative to TPA-Final, and 2 mol% to 4 mol% of isosorbide segments (ISB-Final) relative to TPA-Final. mol% (e.g., 2mol%, 2.2mol%, 2.4mol%, 2.6mol%, 2.8mol%, 3mol%, 3.2mol%, 3.4mol%, 3.6mol%, 3.8mol%, or 4mol%, etc.).

[0008] The PETG resin also includes diethylene glycol segments formed by the etherification reaction of ethylene glycol, with a content of 4 mol% to 8 mol% relative to the segments derived from terephthalic acid (relative to TPA-Final), for example, 4 mol%, 4.5 mol%, 5 mol%, 5.5 mol%, 6 mol%, 6.5 mol%, 7 mol%, 7.5 mol%, or 8 mol%. The diethylene glycol is a byproduct of the etherification reaction of ethylene glycol.

[0009] Preferably, the intrinsic viscosity (IV) of the PETG resin is from 0.60 dl / g to 0.63 dl / g, for example, 0.6 dl / g, 0.605 dl / g, 0.61 dl / g, 0.615 dl / g, 0.62 dl / g, 0.625 dl / g or 0.63 dl / g, etc.

[0010] Furthermore, the intrinsic viscosity (IV) of PETG resin has the following mathematical relationship with its glass transition temperature (Tg): Tg = 77.95 + 7.41 IV+(0.09 CHDM-Final+1.11 ISB-Final-1.21 DEG-Final) 100 In the formula, CHDM-Final, ISB-Final, and DEG-Final represent the contents of 1,4-cyclohexanediethanol, isosorbide, and diethylene glycol segments in PETG resin, respectively.

[0011] The PETG resin of the present invention has excellent transparency and appearance properties, and CHDM-Final and ISB-Final have a significant impact on the transparency of PETG products. The sum of CHDM-Final and ISB-Final is controlled within the range of 8 mol% to 14 mol%.

[0012] Preferably, the isosorbide retention rate in the PETG resin is above 78%.

[0013] On the other hand, the present invention provides a method for preparing the PETG resin as described above, the method comprising the following steps: (a) A dicarboxylic acid component containing terephthalic acid is reacted with a straight-chain alkane diol component containing ethylene glycol and 1,4-cyclohexanediethanol to obtain an intermediate mainly composed of BHET (dihydroxyethyl terephthalate) and BHCT (bis(4-hydroxymethylcyclohexyl terephthalate)). (b) Add a rigid diol component containing isosorbide to the reaction system of step (a) and carry out the reaction; (c) After the reaction in step (b) is completed, a pre-condensation reaction is carried out; (d) After the pre-condensation reaction is completed, the final condensation reaction is carried out in the presence of a polymerization catalyst and a heat stabilizer to obtain the PETG resin.

[0014] This invention employs a stepwise esterification process. The first esterification reaction (step (a)) involves the esterification of conventional straight-chain alkane diols and CHDM. The second esterification reaction (step (b)) involves the esterification of ISB. An esterification catalyst is added during the second esterification reaction, which effectively improves the retention rate of ISB and avoids prolonged exposure of ISB under harsh conditions, thereby improving the color value and transparency of the product.

[0015] Preferably, the reaction in step (a) may be carried out without a catalyst or with an esterification catalyst. The amount of the esterification catalyst added, calculated by the amount of metal element, is from 0 ppm to 15 ppm, for example, 0 ppm, 1 ppm, 3 ppm, 5 ppm, 8 ppm, 10 ppm, 12 ppm or 15 ppm, based on the weight of the final PETG resin as 100%.

[0016] In this invention, the ethylene glycol (EG) feed content is 105 mol% to 110 mol% relative to the terephthalic acid (TPA) feed content (e.g., 105 mol%, 106 mol%, 107 mol%, 108 mol%, or 110 mol%, etc.), the 1,4-cyclohexanediethanol (CHDM) feed content is 7.5 mol% to 10 mol% relative to the TPA (e.g., 7.5 mol%, 8 mol%, 8.5 mol%, 9 mol%, or 10 mol%, etc.), and the isosorbide (ISB) feed content is 2.5 mol% to 5 mol% relative to the TPA (e.g., 2.5 mol%, 3 mol%, 3.5 mol%, 4 mol%, or 5 mol%, etc.).

[0017] Preferably, the esterification catalyst comprises any one or a combination of at least two of the following: acetates, borates, fatty acid salts, carbonates, alkoxy salts, and oxides of zinc, magnesium, cobalt, tin, etc., preferably zinc acetate and / or magnesium acetate.

[0018] Adding an esterification catalyst to the esterification reaction described in step (a) can effectively control the content of diethylene glycol generated by ethylene glycol etherification remaining in the final PETG resin.

[0019] Preferably, the molar ratio of the dicarboxylic acid component to the straight-chain alkane diol component in step (a) is 1:1.15 to 1:1.18, for example, 1:1.15, 1:1.16, 1:1.17 or 1:1.18.

[0020] Preferably, the reaction temperature in step (a) is 210°C to 260°C (e.g., 210°C, 215°C, 220°C, 225°C, 230°C, 235°C, 240°C, 245°C, 250°C, 255°C or 260°C, etc.), preferably 230°C to 250°C.

[0021] Preferably, the reaction time in step (a) is from 180 min to 300 min (e.g., 180 min, 195 min, 210 min, 225 min, 240 min, 255 min, 270 min, 285 min or 300 min, etc.), more preferably from 180 min to 240 min.

[0022] Preferably, the reaction in step (a) is carried out at a relative pressure of 0.2 to 0.3 MPa (e.g., 0 MPa, 0.03 MPa, 0.06 MPa, 0.09 MPa, 0.12 MPa, 0.15 MPa, 0.18 MPa, 0.21 MPa, 0.24 MPa, 0.27 MPa or 0.3 MPa, etc.).

[0023] In this invention, the esterification reaction described in step (a) is carried out until the esterification water yield reaches more than 90% of the theoretical value, thereby obtaining an intermediate mainly composed of BHET (dihydroxyethyl terephthalate) and BHCT (bis(4-hydroxymethylcyclohexyl terephthalate)). The content of DEG in the final resin can be precisely controlled to construct a stable oligomer.

[0024] Preferably, the reaction in step (b) is carried out in the presence of an esterification catalyst.

[0025] Preferably, the esterification catalyst comprises any one or a combination of at least two of the following: acetates, borates, fatty acid salts, carbonates, alkoxy salts, and oxides of zinc, magnesium, cobalt, tin, etc., preferably zinc acetate and / or magnesium acetate.

[0026] Preferably, based on the weight of the final PETG resin (100%), the amount of metal element added in the esterification catalyst is 5 ppm to 30 ppm, for example, 5 ppm, 10 ppm, 15 ppm, 20 ppm, 25 ppm, 30 ppm, etc.

[0027] In step (b), the catalyst can accelerate the esterification and / or transesterification reactions of isosorbide and BHET and BHCT, further shorten the residence time of isosorbide monomer in the high temperature system, reduce the side reactions caused by direct heating of isosorbide, and improve the isosorbide retention rate.

[0028] Preferably, the reaction temperature in step (b) is 230°C to 260°C (e.g., 230°C, 233°C, 236°C, 239°C, 242°C, 245°C, 248°C, 251°C, 254°C, 257°C or 260°C, etc.), more preferably 250°C to 260°C.

[0029] Preferably, the reaction time in step (b) is 60 min to 90 min (e.g., 60 min, 65 min, 70 min, 75 min, 80 min, 85 min or 90 min, etc.), preferably 60 min to 70 min.

[0030] Preferably, the reaction in step (b) is carried out at a relative pressure of -0.05 MPa to 0 MPa (e.g., -0.05 MPa, -0.044 MPa, -0.038 MPa, -0.032 MPa, -0.026 MPa, -0.02 MPa, -0.014 MPa, -0.008 MPa, -0.002 MPa or 0 MPa, etc.), with the relative pressure preferably being 0 MPa.

[0031] In this invention, the reaction in step (b) involves adding a rigid diol component containing isosorbide and an esterification catalyst to the reaction system of step (a) until the esterification water yield reaches more than 95% of the theoretical value. This step is crucial. Isosorbide is introduced later under relatively mild conditions to undergo esterification and / or transesterification reactions with BHET and BHCT generated in the first step, avoiding direct exposure to the strongly acidic environment of PTA and the high temperature and pressure in the early stage, effectively reducing decomposition and discoloration.

[0032] Preferably, the pre-condensation reaction in step (c) is carried out in the presence of a polymerization catalyst.

[0033] Preferably, the polymerization catalyst comprises one or a combination of at least two of titanium-based compounds, germanium-based compounds, and antimony-based compounds. Antimony-based compounds are preferred, and more preferably, a combination of any one or at least two of antimony trioxide, antimony glycolate, and antimony acetate.

[0034] Preferably, the polymerization catalyst, in terms of the amount of metal element, is added in an amount of 100 ppm to 300 ppm, such as 100 ppm, 125 ppm, 150 ppm, 175 ppm, 200 ppm, 225 ppm, 250 ppm, 275 ppm or 300 ppm, based on 100% of the final PETG resin.

[0035] The pre-condensation reaction described in step (c) is carried out under high vacuum and high temperature, which can better remove high-boiling-point monomers and their generated impurities, effectively reduce the side reactions at high temperature during the subsequent final condensation, and achieve the purpose of improving color.

[0036] Preferably, the temperature of the pre-condensation reaction in step (c) is 260°C to 280°C (e.g., 260°C, 262°C, 264°C, 266°C, 268°C, 270°C, 272°C, 274°C, 276°C, 278°C, or 280°C, etc.), and the reaction time is 60 min to 90 min (e.g., 60 min, 65 min, 70 min, 75 min, 80 min, 85 min, or 90 min, etc.).

[0037] Preferably, the pre-condensation reaction in step (c) is carried out under gradually evacuated vacuum to an absolute pressure of 20-200 Pa (e.g., 20 Pa, 40 Pa, 60 Pa, 80 Pa, 100 Pa, 120 Pa, 140 Pa, 160 Pa, 180 Pa or 200 Pa).

[0038] Preferably, the polymerization catalyst in step (d) comprises one or a combination of at least two of titanium-based compounds, germanium-based compounds, and antimony-based compounds. Antimony-based compounds are preferred, and more preferably, any one or a combination of at least two of antimony trioxide, antimony glycolate, and antimony acetate.

[0039] Preferably, the polymerization catalyst, in terms of the amount of metal element, is added in an amount of 100 ppm to 300 ppm, such as 100 ppm, 125 ppm, 150 ppm, 175 ppm, 200 ppm, 225 ppm, 250 ppm, 275 ppm or 300 ppm, based on 100% of the final PETG resin.

[0040] Preferably, the stabilizer in step (d) comprises a phosphorus-based compound, preferably any one or a combination of at least two of phosphoric acid, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, etc. Preferably, the stabilizer is added in an amount of 5 ppm to 50 ppm of phosphorus, based on 100% of the final PETG resin, for example, 5 ppm, 10 ppm, 15 ppm, 20 ppm, 25 ppm, 30 ppm, 35 ppm, 40 ppm, 45 ppm or 50 ppm.

[0041] Preferably, the polycondensation reaction in step (d) is carried out under an absolute pressure of 20-200 Pa (e.g., 20 Pa, 40 Pa, 60 Pa, 80 Pa, 100 Pa, 120 Pa, 140 Pa, 160 Pa, 180 Pa or 200 Pa).

[0042] Preferably, the polycondensation reaction in step (d) is carried out at a temperature of 260°C to 280°C (e.g., 260°C, 262°C, 264°C, 266°C, 268°C, 270°C, 272°C, 274°C, 276°C, 278°C, or 280°C, etc.) and for a reaction time of 150 min to 250 min (e.g., 150 min, 160 min, 170 min, 180 min, 190 min, 200 min, 210 min, 220 min, 230 min, or 250 min, etc.). The PETG resin is obtained by reacting to the target viscosity in step (d).

[0043] In step (d), the reaction is carried out in the presence of a polymerization catalyst and a heat stabilizer under high vacuum and high temperature for final polycondensation, removing small molecules such as ethylene glycol, 1,4-cyclohexanediethanol, and isosorbide, so that the molecular chain increases to the target value. After water cooling and pelletizing, PETG resin granules are obtained.

[0044] On the other hand, the present invention provides the application of PETG resin as described above in the preparation of cosmetic packaging materials.

[0045] Compared with the prior art, the present invention has the following beneficial effects: The PETG resin of this invention can significantly improve isosorbide retention, improve resin hue and transparency, while maintaining low CHDM content. It is an easily recyclable PETG resin that meets the RIC1 resin definition and has good application prospects. Attached Figure Description

[0046] Figure 1 The image shows the 1H NMR spectrum of the PETG polyester copolymer prepared in Example 6 of this invention. Detailed Implementation

[0047] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0048] Example 1 This embodiment provides a PETG resin, the preparation method of which includes the following steps: (a) First esterification reaction (ES1): PTA (1946g), EG (763g), and CHDM (169g) were added to a 10L polymerization reactor. Nitrogen gas was injected into the reactor to create a positive pressure, with a relative pressure of 0.3MPa. The reactor temperature was then increased to 210℃ over 60 min and maintained for 240 min until the esterification water yield reached more than 90% of the theoretical value.

[0049] (b) Second esterification reaction (ES2): Then, with a relative system pressure of -0.05 MPa, ISB (86 g) and zinc acetate (0.10 g) are added to the reactor. The temperature of the reactor is raised to 260 °C and maintained for 90 min until the esterification water yield reaches more than 95% of the theoretical value.

[0050] (c) Pre-condensation reaction: Then gradually raise the temperature to 270°C and slowly evacuate to an absolute pressure of 200 Pa to carry out the pre-condensation reaction for 60 min.

[0051] (d) Final polycondensation reaction: Antimony trioxide (0.85 g) and trimethyl phosphate (0.16 g) were used as polymerization catalysts. The pressure in the reactor was then maintained at an absolute pressure of 20 Pa for the polycondensation reaction, the reaction temperature was 270 °C, and the reaction time was 250 min, until the intrinsic viscosity of the mixture in the reactor reached 0.64 dL / g. After water cooling, the mixture was pelletized to obtain PETG pellets.

[0052] The PETG resin ISB prepared in this way has a retention rate of 80%, a glass transition temperature of 78.4℃, a color value L=67, a b value=2.3, and a haze of 0.3% for a 3mm thick sheet made from this resin.

[0053] Example 2 This embodiment provides a PETG resin, the preparation method of which includes the following steps: (a) First esterification reaction (ES1): PTA (1965g), EG (797g), and CHDM (128g) were added to a 10L polymerization reactor. Nitrogen gas was injected into the reactor to create a positive pressure, with a relative pressure of 0.2MPa. The reactor temperature was then increased to 240℃ over 60 min and maintained for 150 min until the esterification water yield reached more than 90% of the theoretical value.

[0054] (b) Second esterification reaction (ES2): Then the system is restored to a relative pressure of 0 MPa, and ISB (69 g) and zinc acetate (0.20 g) are added to the reactor. The temperature of the reactor is raised to 250°C and maintained for 80 min until the esterification water yield reaches more than 95% of the theoretical value.

[0055] (c) Pre-condensation reaction: Then gradually raise the temperature to 280°C and slowly evacuate to an absolute pressure of 20 Pa to carry out the pre-condensation reaction for 90 min.

[0056] (d) Final polycondensation reaction: Antimony acetate (1.05 g) was used as the polymerization catalyst and triethyl phosphate (0.42 g) was used as the stabilizer. The pressure in the reactor was then maintained at an absolute pressure of 20 Pa while the polycondensation reaction was carried out at a reaction temperature of 280 °C until the intrinsic viscosity of the mixture in the reactor reached 0.61 dL / g. After water cooling, the mixture was pelletized to obtain PETG pellets.

[0057] The PETG resin ISB prepared in this way has a retention rate of 83%, a glass transition temperature of 77.6℃, a color value L=69, a color value b=1.5, and a haze of 0.2% for a 3mm thick sheet made from this resin.

[0058] Example 3 This embodiment provides a PETG resin, the preparation method of which includes the following steps: (a) First esterification reaction (ES1): PTA (2557g), EG (1032g), CHDM (200g), magnesium acetate (0.14g), and zinc acetate (0.13g) were added to a 10L polymerization reactor. Nitrogen gas was injected into the reactor to create a positive pressure, and the relative pressure of the reactor was 0.2MPa. Then, the temperature of the reactor was increased to 260℃ over 60 min and maintained for 120 min until the esterification water yield reached more than 90% of the theoretical value.

[0059] (b) Second esterification reaction (ES2): Then the system is restored to a relative pressure of 0 MPa, and ISB (67 g) and zinc acetate (0.13 g) are added to the reactor. The temperature of the reactor is raised to 250°C and maintained for 60 min until the esterification water yield reaches more than 95% of the theoretical value.

[0060] (c) Pre-condensation reaction: Then gradually raise the temperature to 260°C and slowly evacuate to an absolute pressure of 200Pa to carry out the pre-condensation reaction for 90 minutes.

[0061] (d) Final polycondensation reaction: Antimony glycolate (0.68 g) was used as the polymerization catalyst, and triphenyl phosphate (0.50 g) was used as the stabilizer. The reactor pressure was then maintained at 200 Pa absolute pressure while the polycondensation reaction was carried out at a reaction temperature of 260 °C for 250 min until the intrinsic viscosity of the mixture in the reactor reached 0.60 dL / g. After water cooling, the mixture was pelletized to obtain PETG pellets.

[0062] The PETG resin ISB prepared in this way has a retention rate of 80%, a glass transition temperature of 79.9℃, a color value L=64, a b value=2.8, and a haze of 0.3% for a 3mm thick sheet made from this resin.

[0063] Example 4 This embodiment provides a PETG resin, the preparation method of which includes the following steps: (a) First esterification reaction (ES1): PTA (1946g), EG (794g), CHDM (144g), and magnesium acetate (0.31g) were added to a 10L polymerization reactor. Nitrogen gas was injected into the reactor to create a positive pressure state, and the relative pressure of the reactor was 0.2MPa. Then, the temperature of the reactor was raised to 235℃ over 60 min and maintained for 180 min until the esterification water yield reached more than 90% of the theoretical value.

[0064] (b) Second esterification reaction (ES2): Then the system is restored to a relative pressure of 0 MPa, and ISB (39 g) and zinc acetate (0.05 g) are added to the reactor. The temperature of the reactor is raised to 230°C and maintained for 90 min until the esterification water yield reaches more than 95% of the theoretical value.

[0065] (c) Pre-condensation reaction: Then gradually raise the temperature to 270°C and slowly evacuate to an absolute pressure of 200 Pa to carry out the pre-condensation reaction for 90 min.

[0066] (d) Final polycondensation reaction: Antimony glycolate (0.51 g) was used as the polymerization catalyst and phosphoric acid (0.11 g) as the stabilizer. The pressure in the reactor was then maintained at an absolute pressure of 50 Pa while the polycondensation reaction was carried out at a reaction temperature of 270 °C for 210 min until the intrinsic viscosity of the mixture in the reactor reached 0.60 dL / g. After water cooling, the mixture was pelletized to obtain PETG pellets.

[0067] The PETG resin ISB prepared in this way has a retention rate of 80%, a glass transition temperature of 80.5℃, a color value L=61, a b value=4.0, and a haze of 1.5% for a 3mm thick sheet made from this resin.

[0068] Example 5 This embodiment provides a PETG resin, the preparation method of which includes the following steps: (a) First esterification reaction (ES1): PTA (1981g), EG (795g), CHDM (146g), and magnesium acetate (0.11g) were added to a 10L polymerization reactor. Nitrogen gas was injected into the reactor to create a positive pressure, and the relative pressure of the reactor was 0.2MPa. The temperature of the reactor was then increased to 240℃ over 60 min and maintained for 190 min until the esterification water yield reached more than 90% of the theoretical value.

[0069] (b) Second esterification reaction (ES2): Then the system is restored to a relative pressure of 0 MPa, and ISB (70 g) and zinc acetate (0.10 g) are added to the reactor. The temperature of the reactor is raised to 250°C and maintained for 60 min until the esterification water yield reaches more than 95% of the theoretical value.

[0070] (c) Pre-condensation reaction: Then gradually raise the temperature to 265°C and slowly evacuate to an absolute pressure of 200 Pa to carry out the pre-condensation reaction for 70 min.

[0071] (d) Final polycondensation reaction: Antimony glycolate (0.63 g) was used as the polymerization catalyst, and phosphoric acid (0.11 g) was used as the stabilizer. The pressure in the reactor was then maintained at an absolute pressure of 50 Pa while the polycondensation reaction was carried out at a reaction temperature of 265 °C for 150 min until the intrinsic viscosity of the mixture in the reactor reached 0.64 dL / g. After water cooling, the mixture was pelletized to obtain PETG pellets.

[0072] The PETG resin ISB prepared in this way has a retention rate of 80%, a glass transition temperature of 80.4℃, a color value L=66, a color value b=2.6, and a haze of 0.4% for a 3mm thick sheet made from this resin.

[0073] Example 6 This embodiment provides a PETG resin, the preparation method of which includes the following steps: (a) First esterification reaction (ES1): PTA (1946g), EG (794g), CHDM (145g), and magnesium acetate (0.31g) were added to a 10L polymerization reactor. Nitrogen gas was injected into the reactor to create a positive pressure, and the relative pressure of the reactor was 0.2MPa. Then, the temperature of the reactor was increased to 235℃ over 60 min and maintained for 180 min until the esterification water yield reached more than 90% of the theoretical value.

[0074] (b) Second esterification reaction (ES2): Then the system is restored to a relative pressure of 0 MPa, and ISB (51 g) and zinc acetate (0.05 g) are added to the reactor. The temperature of the reactor is raised to 230°C and maintained for 90 min until the esterification water yield reaches more than 95% of the theoretical value.

[0075] (c) Pre-condensation reaction: Then gradually raise the temperature to 270°C and slowly evacuate to an absolute pressure of 200 Pa to carry out the pre-condensation reaction for 90 min.

[0076] (d) Final polycondensation reaction: Antimony glycolate (0.51 g) was used as the polymerization catalyst and phosphoric acid (0.11 g) as the stabilizer. The pressure in the reactor was then maintained at an absolute pressure of 50 Pa while the polycondensation reaction was carried out at a reaction temperature of 270 °C for 210 min until the intrinsic viscosity of the mixture in the reactor reached 0.60 dL / g. After water cooling, the mixture was pelletized to obtain PETG pellets.

[0077] The PETG resin ISB prepared in this way has a retention rate of 80%, a glass transition temperature of 81.5℃, a color value L=62, a b value=2.5, and a haze of 0.6% for a 3mm thick sheet made from this resin.

[0078] Comparative Example 1 This comparative example provides a PETG resin, the preparation method of which includes the following steps: (a) First esterification reaction (ES1): PTA (2592g), EG (1016g), and CHDM (180g) were added to a 10L polymerization reactor. Nitrogen gas was injected into the reactor to create a positive pressure state, and the relative pressure of the reactor was 0.2MPa. Then, the temperature of the reactor was increased to 240℃ over 60 min and maintained for 210 min until the esterification water yield reached more than 90% of the theoretical value.

[0079] (b) Second esterification reaction (ES2): Then the system is restored to a relative pressure of 0 MPa, and the temperature of the reactor is raised to 255°C and maintained for 90 min until the esterification water yield reaches more than 95% of the theoretical value.

[0080] (c) Pre-condensation reaction: Then gradually raise the temperature to 275°C and slowly evacuate to an absolute pressure of 200 Pa to carry out the pre-condensation reaction for 90 min.

[0081] (d) Final polycondensation reaction: Antimony glycolate (0.80 g) was used as the polymerization catalyst, and phosphoric acid (0.15 g) was used as the stabilizer. The reactor pressure was then maintained at 50 Pa absolute pressure while the polycondensation reaction proceeded until the intrinsic viscosity of the mixture in the reactor reached 0.63 dL / g. The mixture was then water-cooled and pelletized to obtain PETG pellets. The PETG resin prepared in this manner had a glass transition temperature of 78.1 °C, a color value L=60, a b value=3, and a haze of 4.0% for a 3 mm thick sheet made from this resin.

[0082] Comparative Example 2 This comparative example provides a PETG resin, the preparation method of which includes the following steps: Comparative Example 2 uses the same raw material ratio as Example 5, but is prepared using a "one-pot method". The specific preparation steps are as follows: PTA (1981g), EG (796g), CHDM (146g), magnesium acetate (0.11g), zinc acetate (0.10g), and ISB (70g) were added to a 10L polymerization reactor. Nitrogen gas was injected into the reactor to create a positive pressure, with a relative pressure of 0.2MPa. The reactor temperature was then increased to 240℃ over 60 minutes and maintained for 190 minutes until the esterification water yield reached more than 90% of the theoretical value. The system was then restored to a relative pressure of 0MPa, and the reactor temperature was increased to 250℃ and maintained for 60 minutes until the esterification water yield reached more than 95% of the theoretical value.

[0083] (b) Pre-condensation reaction: Then gradually raise the temperature to 265°C and slowly evacuate to an absolute pressure of 200 Pa to carry out the pre-condensation reaction for 70 min.

[0084] (c) Final polycondensation reaction: Antimony glycolate (0.63 g) was used as the polymerization catalyst and phosphoric acid (0.11 g) as the stabilizer. The pressure in the reactor was then maintained at an absolute pressure of 50 Pa while the polycondensation reaction was carried out at a reaction temperature of 265 °C for 150 min until the intrinsic viscosity of the mixture in the reactor reached 0.64 dL / g. After water cooling, the mixture was pelletized to obtain PETG pellets.

[0085] The PETG resin ISB prepared in this way has a retention rate of 50.0%, a glass transition temperature of 77.8℃, a color value L=56, a color value b=8, and a haze of 1.0% for a 3mm thick sheet made from this resin.

[0086] Comparative Example 3 This comparative example provides a PETG resin, the preparation method of which includes the following steps: Comparative Example 3 used the same raw material ratio as Example 5, and the esterification process employed a pre-ISB esterification route. The specific preparation steps are as follows: (a) First esterification reaction (ES1): PTA (1981g), ISB (70g) and zinc acetate (0.10g) are added to a 10L reactor. The relative pressure of the reactor is adjusted to 0MPa. The temperature of the reactor is raised to 250℃ and maintained for 60min until the esterification water yield reaches more than 90% of the theoretical value.

[0087] (b) Second esterification reaction (ES2): EG (796g), CHDM (146g) and magnesium acetate (0.11g) were added to the reactor, and the relative pressure of the reactor was adjusted to 0.2MPa. Then the temperature of the reactor was raised to 240℃ over 60 min and maintained for 190 min until the esterification water yield reached more than 95% of the theoretical value.

[0088] (c) Pre-condensation reaction: Then gradually raise the temperature to 265°C and slowly evacuate to an absolute pressure of 200 Pa to carry out the pre-condensation reaction for 70 min.

[0089] (d) Final polycondensation reaction: Antimony glycolate (0.63 g) was used as the polymerization catalyst, and phosphoric acid (0.11 g) was used as the stabilizer. The pressure in the reactor was then maintained at an absolute pressure of 50 Pa while the polycondensation reaction was carried out at a reaction temperature of 265 °C for 150 min until the intrinsic viscosity of the mixture in the reactor reached 0.63 dL / g. After water cooling, the mixture was pelletized to obtain PETG pellets.

[0090] The PETG resin ISB prepared in this way has a retention rate of 70.0%, a glass transition temperature of 77.3℃, a color value L=62, a color value b=4.3, and a haze of 1.3% for a 3mm thick sheet made from this resin.

[0091] Test methods for the main physical properties of the PETG resins prepared in the above examples and comparative examples: (1) Intrinsic viscosity (IV): According to GB / T 14190:2017, weigh (0.125±0.005) g of sample and dissolve it in 25 mL of phenol / 1,1,2,2-tetrachloroethane (mass ratio 60:40) to prepare a solution. Calculate the concentration (c, g / mL) of the actual test solution. After filtering the solution, add it to an Ubbelohde viscometer (φ=0.800 mm). After maintaining the temperature in a constant temperature water bath at 25.00±0.05℃ for 15 min, measure the time it takes for the solvent and solution to flow through the upper and lower marks of the Ubbelohde viscometer. Repeat the measurement 3 times, and the average value is the solvent flow time (t0) and the solution flow time (t1). Intrinsic viscosity IV = 0.25[t1 / t0-1+3ln(t1 / t0)] / c.

[0092] (2) Chemical composition of the final product and ISB retention rate: 5 mg of PETG resin was dissolved in 0.5 ml of deuterated chloroform / deuterated trifluoroacetic acid solution (v / v=9:1) until completely dissolved. The composition of PETG resin derived from ethylene glycol, 1,4-cyclohexanediethanol, isosorbide, and diethylene glycol segments relative to terephthalic acid was confirmed by collecting NMR spectra using an Avance-600. That is, with the terephthalic acid segment content (PTA-Final) in the PETG resin product as 100%, the content of ethylene glycol segment (EG-Final), 1,4-cyclohexanediethanol segment (CHDM-Final), isosorbide segment (ISB-Final), and diethylene glycol segment (DEG-Final) was calculated by measuring the molar ratio.

[0093] The ISB retention rate is the ratio of the final product ISB-Final to the isosorbide content (ISB) of the initial feed × 100%.

[0094] (3) Glass transition temperature (Tg) and relative crystallinity (Xc): An aluminum crucible containing 5-10 mg of sample was placed in a DSC. After eliminating the thermal history, the temperature was lowered from 280 °C to 30 °C at a rate of 10 °C / min, held for 3 min, and then raised to 280 °C at a rate of 10 °C / min. Tg was taken as the midpoint of the step on the heating curve.

[0095] The relative crystallinity (Xc) is the ratio of the melting enthalpy (ΔHm) on the heating curve to the equilibrium melting enthalpy (140 J / g) × 100%.

[0096] (4) Color value: The b value of the resin in the Hunter Lab color system was measured using a spectrophotometer according to ASTM D2244. Ultrascan VIS spectral range 360-780nm, D65 light source, 45° viewing angle.

[0097] (5) Haze: Prepare a sample with a thickness of 3 mm and measure the haze of the sample using a spectrophotometer according to the test method specified by ASTM D100397.

[0098] The feeding ratios of each component in the above examples and comparative examples, as well as the performance test results of the obtained polymers, are shown in Table 1 below.

[0099] Table 1 The content of diacid and diol segments in the experimental results was determined by... 1The deuterated reagent used in the NMR characterization was a deuterated chloroform / deuterated trifluoroacetic acid solution (v / v = 9:1). The chemical structural formulas of the samples corresponding to Examples 1-6 are as follows: Table 2 shows the chemical shifts and calculation methods of the peaks corresponding to hydrogen at various positions in the sample in the NMR spectrum, where I 化学位移 This represents the integral area at that location. For example, the NMR spectrum of the PETG resin obtained in Example 6 is shown below. Figure 1 As shown, according to Figure 1 The integral area of ​​the relative peaks marked in the table can be used to obtain the component content results for Example 6 recorded in Table 1.

[0100] Table 2 The applicant declares that the present invention illustrates the PETG resin, its preparation method, and its application through the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A PETG resin, characterized in that, The PETG resin comprises segments formed by a dicarboxylic acid component and a straight-chain alkane diol component, as well as segments formed by a dicarboxylic acid component and a rigid diol component. The dicarboxylic acid component comprises terephthalic acid, the straight-chain alkane diol component comprises ethylene glycol and 1,4-cyclohexanediethanol, and the rigid diol component comprises isosorbide. The PETG resin contains, relative to the segments derived from terephthalic acid, 80 mol% to 85 mol% of ethylene glycol segments, 7 mol% to 10 mol% of 1,4-cyclohexanediethanol segments, and 2 mol% to 4 mol% of isosorbide segments.

2. The PETG resin according to claim 1, characterized in that, The PETG resin also includes diethylene glycol segments formed by the etherification reaction of ethylene glycol, the content of which is 4 mol% to 8 mol% relative to segments derived from terephthalic acid.

3. The PETG resin according to claim 1 or 2, characterized in that, The intrinsic viscosity (IV) of the PETG resin is from 0.60 dl / g to 0.63 dl / g.

4. The PETG resin according to any one of claims 1-3, characterized in that, The isosorbide retention rate in the PETG resin is over 78%.

5. A method for preparing PETG resin according to any one of claims 1-4, characterized in that, The preparation method includes the following steps: (a) A dicarboxylic acid component containing terephthalic acid is reacted with a straight-chain alkane diol component containing ethylene glycol and 1,4-cyclohexanediethanol to obtain an intermediate mainly composed of bis(4-hydroxymethylcyclohexyl terephthalate) and bis(4-hydroxymethylcyclohexyl terephthalate). (b) Add a rigid diol containing isosorbide to the reaction system of step (a) and carry out the reaction; (c) After the reaction in step (b) is completed, a pre-condensation reaction is carried out; (d) After the pre-condensation reaction is completed, the final condensation reaction is carried out in the presence of a polymerization catalyst and a heat stabilizer to obtain the PETG resin.

6. The preparation method according to claim 5, characterized in that, The reaction described in step (a) may or may not use an esterification catalyst; Preferably, the esterification catalyst comprises any one or a combination of at least two of the following: acetates, borates, fatty acid salts, carbonates, alkoxy salts or oxides of zinc, magnesium, cobalt, tin, etc., preferably zinc acetate and / or magnesium acetate. Preferably, the amount of the esterification catalyst added, in terms of the amount of metal elements, is 0 ppm to 15 ppm, based on 100% of the final PETG resin weight.

7. The preparation method according to claim 5 or 6, characterized in that, In step (a), the content of ethylene glycol relative to the content of terephthalic acid is 105 mol% to 110 mol%, and the content of 1,4-cyclohexanediethanol relative to the content of terephthalic acid is 7.5 mol% to 10 mol%; the content of isosorbide relative to the content of terephthalic acid is 2.5 mol% to 5 mol%. Preferably, the temperature of the reaction in step (a) is 210°C to 260°C, more preferably 230°C to 250°C; Preferably, the reaction time in step (a) is 180 min to 300 min, more preferably 180 min to 240 min; Preferably, the reaction in step (a) is carried out at a relative pressure of 0.2 to 0.3 MPa.

8. The preparation method according to any one of claims 5-7, characterized in that, The reaction described in step (b) is carried out in the presence of an esterification catalyst; Preferably, in step (b), the isosorbide content is 2.5 mol% to 5 mol% relative to the terephthalic acid content. Preferably, the esterification catalyst comprises any one or a combination of at least two of the following: acetates, borates, fatty acid salts, carbonates, alkoxy salts or oxides of zinc, magnesium, cobalt, tin, etc., preferably zinc acetate and / or magnesium acetate. Preferably, based on the weight of the final PETG resin (100%), the amount of the esterification catalyst added, in terms of the amount of metal elements, is 5 ppm to 30 ppm. Preferably, the reaction temperature in step (b) is 230°C to 260°C, more preferably 250°C to 260°C; Preferably, the reaction time in step (b) is 60 min to 90 min, more preferably 60 min to 70 min; Preferably, the reaction in step (b) is carried out at a relative pressure of -0.05 MPa to 0 MPa, and more preferably at a relative pressure of 0 MPa.

9. The preparation method according to any one of claims 5-8, characterized in that, The pre-condensation reaction described in step (c) is carried out in the presence of a polymerization catalyst; Preferably, the polymerization catalyst comprises one or a combination of at least two of titanium-based compounds, germanium-based compounds, or antimony-based compounds; preferably, it comprises antimony-based compounds, and more preferably, it comprises any one or a combination of at least two of antimony trioxide, antimony glycolate, and antimony acetate. Preferably, the polymerization catalyst, in terms of the amount of metal element, is added at a rate of 100 ppm to 300 ppm, based on 100% of the final PETG resin weight. Preferably, the temperature of the pre-condensation reaction in step (c) is 260°C to 280°C, and the reaction time is 60 to 90 min; Preferably, the pre-condensation reaction in step (c) is carried out under vacuum gradually to an absolute pressure of 20-200 Pa; Preferably, the polymerization catalyst in step (d) comprises one or a combination of at least two of titanium-based compounds, germanium-based compounds, or antimony-based compounds; preferably, it comprises antimony-based compounds, and more preferably, it comprises any one or a combination of at least two of antimony trioxide, antimony glycolate, and antimony acetate. Preferably, the polymerization catalyst, in terms of the amount of metal element, is added at a rate of 100 ppm to 300 ppm, based on 100% of the final PETG resin weight. Preferably, the stabilizer in step (d) comprises a phosphorus-based compound, preferably any one or a combination of at least two of phosphoric acid, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, etc. Preferably, the stabilizer is added in an amount of 5 ppm to 50 ppm of phosphorus, based on 100% of the final PETG resin weight. Preferably, the polycondensation reaction in step (d) is carried out at an absolute pressure of 20-200 Pa; Preferably, the polycondensation reaction in step (d) is carried out at a temperature of 260°C to 280°C for a reaction time of 150-250 min.

10. The use of the PETG resin according to any one of claims 1-4 in the preparation of cosmetic packaging materials.

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