Highly transparent alicyclic copolyester and method for preparing the same

Abstract

The present application relates to a kind of high transparent alicyclic copolyester and its preparation method, belong to the preparation field of polyester material.Copolyester includes tricyclodecane diol unit and diacid unit, the tricyclodecane diol unit is at least one of tricyclodecane dimethyl alcohol, monoethoxylated tricyclodecane dimethyl alcohol or diethoxylated tricyclodecane dimethyl alcohol.Preparation method includes: with alicyclic or aromatic diacid, diol copolymerization, and the modified copolyester of high transparency promotion heat resistance is prepared.The toughening effect is played to the copolyester structure by introducing tricyclodecane dimethyl alcohol with rigid bridge ring structure into the copolyester structure after being modified by ethoxylation, while the glass transition temperature and light transmittance of polyester material are improved.The non-crystalline copolyester prepared has high transparency and higher heat resistance temperature, and has good use prospect in different civil and industrial fields.

Description

Technical Field

[0001] This invention belongs to the field of polyester material preparation, specifically relating to a highly transparent copolyester obtained by polymerization of diacids and alicyclic diols and its preparation method. Background Technology

[0002] Polyester materials, due to their excellent mechanical properties, thermal stability, and processing performance, have become one of the most widely used polymer materials, occupying an important position in fields such as fibers, films, bottle flakes, and engineering plastics. With the upgrading of consumption and the increasing requirements for environmental protection, the market demand for new polyester materials with high transparency, high heat resistance, safety, and non-toxicity is growing, especially in applications such as food packaging, infant products, and medical equipment.

[0003] PETG copolyester, prepared using 1,4-cyclohexanediethanol as a special monomer, possesses high transparency, toughness, chemical resistance, and scratch resistance. It is also free of bisphenol A (BPA), which is harmful to the human body, and does not produce unpleasant odors during heat processing. It is an ideal alternative to transparent materials such as PC, PMMA, and PVC, and is widely used in the sheet, plate, and bottle markets. Eastman's Tritan copolyester, containing the special monomer cyclobutanediol (CBDO), has a heat resistance exceeding 100°C, high transparency, strong resistance to yellowing, and excellent biocompatibility, making it suitable for applications in food contact containers, baby bottles, and medical devices. However, cyclobutanediol (CBDO) has low reactivity, making it difficult to effectively incorporate into polyester materials and significantly increasing costs. Therefore, there is a broad market demand for introducing other types of special monomers to improve heat resistance and light transmittance to prepare high-heat-resistant and high-transparency polyester materials.

[0004] Tricyclodecanediethanol (TCDDM), a rigid alicyclic diol containing multiple isomers, exhibits high reactivity in polymerization reactions. Its multiple isomers contribute to the amorphous properties of polyesters. The three-membered alicyclic ring effectively enhances the light transmittance and glass transition temperature of the material, making it suitable for preparing novel copolyester materials. However, due to its rigid tricyclic configuration containing bridging bonds, the polymer exhibits insufficient tensile strength and poor toughness, necessitating further structural optimization to address these performance defects. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a copolyester with high transparency and improved heat resistance having an alicyclic structure. On the other hand, in view of the insufficient toughness of tricyclodecanediethanol (TCDDM) in polyester applications, TCDDM is modified by ethoxylation, and flexible bonds are introduced into the molecule to improve the toughness and other properties of the copolyester material.

[0006] The objective of this invention can be achieved through the following technical solutions: In a first aspect, the present invention provides a highly transparent alicyclic copolyester, the copolyester comprising a tricyclic decanediol unit and a diacid unit; The tricyclic decanediol unit is at least one of the following structures:

[0007]

[0008]

[0009] The dicarboxylic acid unit is at least one of tricyclic decanedicarboxylic acid and aromatic dicarboxylic acid.

[0010] As used herein, the term "tricyclic decanediol unit" refers to a structural unit derived from tricyclic decanediethanol (TCDDM) or its derivatives, including but not limited to monoethoxylated tricyclic decanediethanol (TCDDMEO) and dieethoxylated tricyclic decanediethanol (TCDDM2EO). The tricyclic decane backbone contains three fused cyclohexane rings, forming a rigid bridged ring structure, which helps to improve the glass transition temperature and dimensional stability of polyester materials.

[0011] The tricyclic decanediol unit contains multiple isomers, which are difficult to form a regular crystal structure during polymerization, thus causing the copolyester to exhibit an amorphous or hypocrystalline state. At the same time, the rigid tricyclic structure restricts the thermal motion of the molecular chains, which is beneficial to increasing the glass transition temperature.

[0012] The "tricyclic decanedicarboxylic acid" (TCD-DA) described in this invention refers to a dicarboxylic acid compound with tricyclic decane as its core. Similar to the tricyclic decane diol unit, its isomerism helps to disrupt the regularity of the molecular chain and maintain the amorphous state of the copolyester. The structure of the tricyclic decanedicarboxylic acid is as follows:

[0013] Preferably, the aromatic dicarboxylic acid is at least one selected from terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid. When an aromatic dicarboxylic acid is used, the introduction of an aromatic ring structure into the copolyester can improve the rigidity and heat resistance of the material while maintaining high light transmittance.

[0014] Preferably, the copolyester further comprises at least one of 1,4-cyclohexanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, isosorbide, and 1,6-hexanediol. The purpose of introducing these other diols is to further regulate the properties of the copolyester. For example, the alicyclic structure of 1,4-cyclohexanediol helps maintain the transparency and heat resistance of the material; aliphatic diols such as 1,4-butanediol can increase the flexibility of the molecular chain, improving the processing performance and toughness of the material; and isosorbide, as a bio-based diol, can enhance the environmental properties and rigidity of the material.

[0015] Preferably, the molar ratio of the dicarboxylic acid component to the diol component in the copolyester is 1:1 to 1:1.5.

[0016] Secondly, the present invention provides a method for preparing a highly transparent alicyclic copolyester, comprising the following steps: (1) The dicarboxylic acid component, the diol component and the catalyst are mixed and esterified at 170℃~250℃ to obtain the esterification intermediate; (2) Add a catalyst and a phosphorus stabilizer to the esterification intermediate obtained in step (1) and carry out a polycondensation reaction to obtain the high transparency alicyclic copolyester.

[0017] Esterification can be carried out under normal or pressurized conditions, with a reaction time typically ranging from 2 to 6 hours, which can be adjusted based on the reactivity of the monomers. Polycondensation typically takes 2 to 5 hours, ending when the reaction system reaches the desired melt viscosity or molecular weight.

[0018] Preferably, the catalyst is selected from at least one of titanium-based catalysts, antimony-based catalysts, tin-based catalysts, and germanium-based catalysts.

[0019] Preferably, the phosphorus-based stabilizer is selected from at least one of trimethyl phosphate, triphenyl phosphate, phosphorous acid, hypophosphite, triisooctyl phosphite, and triphenyl phosphite. The main function of the phosphorus-based stabilizer is to complex the metal ions in the catalyst, inhibiting side reactions at high temperatures and preventing discoloration and degradation of the polyester. Simultaneously, the phosphorus-based stabilizer can also improve the thermal stability and antioxidant properties of the polyester.

[0020] Preferably, the polycondensation reaction conditions in step (2) are: vacuum degree 10Pa~200Pa and temperature 250℃~280℃. High vacuum degree can accelerate the removal of small molecule byproducts (such as ethylene glycol and water).

[0021] Thirdly, the present invention provides an application of a highly transparent alicyclic copolyester in food packaging materials, baby bottles, water cups, optical films, or medical devices.

[0022] The highly transparent alicyclic copolyester prepared by this invention possesses excellent light transmittance (88%-91%) and a high glass transition temperature (82℃-102℃), and is free of harmful substances such as bisphenol A. Therefore, it is particularly suitable for fields with high requirements for transparency, heat resistance, and safety. In the food packaging field, it can be used for transparent containers and food storage boxes; in the infant and toddler product field, it can be used for baby bottles and water cups; in the optical film field, it can be used for polarizing film protective films, brightness enhancement films, etc.; in the medical device field, it can be used for transparent protective covers, catheters, infusion components, etc.

[0023] The copolyester of this invention can also be blended or co-extruded with other polymer materials to prepare multilayer composite structures to meet specific performance requirements. For example, blending with polycarbonate can further improve heat resistance.

[0024] The beneficial effects of this invention are as follows: (1) The present invention uses alicyclic tricyclic decanediethanol and its ethoxylate to react with alicyclic diacid tricyclic decanedicarboxylic acid or aromatic diacid to prepare a non-crystalline high-transparency polyester; at the same time, tricyclic decanediethanol and its ethoxylate have a di-primary alcohol structure, which has high reactivity and is easy to prepare high molecular weight copolyester.

[0025] (2) Diol tricyclodecanediethanol and its ethoxylated derivatives, as well as diacid tricyclodecanedicarboxylic acid, are monomers containing multiple isomers. The resulting copolyesters are non-crystalline and can be used to prepare highly transparent copolyesters. After copolymerization with aromatic diacids, highly transparent and heat-resistant copolyesters can be prepared. The glass transition temperature of the prepared copolyesters is 82-102℃, and the light transmittance is 88%-91%. They have good application prospects in food packaging, infant bottles, water cups, and optical films. Attached Figure Description

[0026] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0027] Figure 1 Mass spectrum of the intermediate ethoxylated tricyclodecanediethanol TCDDMEO product; Figure 2 The 1H NMR spectrum of Example 4 1 H NMR. Detailed Implementation

[0028] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided.

[0029] Ethoxylated TCDDM derivatives can be prepared by the following steps: Diol TCDDM and alkali metal catalyst (such as NaOH or KOH, added at 0.3% of the alcohol mass) were added to a stainless steel reactor. The temperature was raised to 120°C, and different molar amounts of ethylene oxide were slowly introduced under stirring. After the introduction was completed, the reactor was aged for 1 hour, cooled and neutralized to pH 7, and then separated by distillation to obtain TCDDMEO and TCDDM2EO products, respectively.

[0030] When the target product is monoethoxylated tricyclodecanediethanol (TCDDMEO), the molar ratio of ethylene oxide to TCDDM is 1:1 to 1.2:1; when the target product is dieethoxylated tricyclodecanediethanol (TCDDM2EO), the molar ratio of ethylene oxide to TCDDM is 2:1 to 2.2:1.

[0031] Example 1 Tricyclodecanedicarboxylic acid (TCD-DA) and monoethoxylated tricyclodecanediethanol (TCDDMEO) were added to a reactor at a molar ratio of TCD-DA to TCDDMEO of 1:1.2. The system was purged under a nitrogen atmosphere. Then, 0.01% of the molar amount of TCD-DA catalyst tetrabutyl titanate was added, followed by stirring and heating to 200°C for esterification reaction for 4 hours. Next, 0.1 mol% of TCD-DA tetrabutyl titanate and 0.05 mol% of the stabilizer triethyl phosphate were added, and the temperature was raised to 220°C and the pressure to 100 Pa for polycondensation for 3 hours. After cooling, copolyester product 1 was obtained.

[0032] Example 2 Tricyclodecanedicarboxylic acid (TCD-DA), tricyclodecanediethanol (TCDDM), and monoethoxylated tricyclodecanediethanol (TCDDMEO) were added to a reactor at a molar ratio of TCD-DA to TCDDM and TCDDMEO of 1:0.35:0.85. The system was purged under a nitrogen atmosphere. Then, 0.008% of TCD-DA was added as a catalyst, tetrabutyl titanate, and the mixture was stirred and heated to 180°C for 4 hours for esterification. Next, 0.12 mol% of TCD-DA was added as a catalyst, manganese acetate, and 0.05 mol% as a stabilizer, triphenyl phosphate. The mixture was then heated to 220°C and subjected to polycondensation at 100 Pa for 3 hours. After cooling, copolyester product 2 was obtained.

[0033] Example 3 Tricyclodecanedicarboxylic acid (TCD-DA), tricyclodecanediethanol (TCDDM), and diethoxylated tricyclodecanediethanol (TCDDM2EO) were added to a reactor at a molar ratio of TCD-DA to TCDDM and TCDDM2EO of 1:0.85:0.35. The system was purged under a nitrogen atmosphere. Then, 0.008% of tetrabutyl titanate as a catalyst (TCD-DA) was added, followed by stirring and heating to 180°C for esterification reaction for 4 hours. Next, 0.12 mol% of antimony glycolate (TCD-DA) and 0.05 mol% of triethyl phosphate as a stabilizer were added, and the temperature was raised to 220°C and the pressure to 100 Pa for polycondensation for 3 hours. After cooling, copolyester product 3 was obtained.

[0034] Example 4 Terephthalic acid (PTA) and monoethoxylated tricyclodecanediethanol (TCDDMEO) were added to a reactor at a molar ratio of 1:1.3. The system was purged under a nitrogen atmosphere, and then 0.1 mol% of zinc acetate catalyst (PTA molar amount) was added. The mixture was then stirred and heated to 180°C for esterification for 4 hours. Next, 0.12 mol% of antimony glycolate (PTA molar amount) and 0.05 mol% of triphenyl phosphate stabilizer were added, and the mixture was then heated to 240°C and subjected to polycondensation at 80 Pa for 4 hours. After cooling, copolyester product 4 was obtained.

[0035] Example 5 Terephthalic acid (PTA), tricyclodecanediethanol (TCDDM), and diethoxylated tricyclodecanediethanol (TCDDM2EO) were added to a reactor at a molar ratio of PTA to TCDDM and TCDDM2EO of 1:0.65:0.55. The system was purged under a nitrogen atmosphere. Zinc acetate catalyst (0.1 mol% of PTA) was added, and the mixture was stirred and heated to 180°C for esterification for 4 hours. Antimony glycolate (0.12 mol% of PTA) and triphenyl phosphate stabilizer (0.05 mol% of triphenyl phosphate) were then added, followed by polycondensation at 240°C and 80 Pa for 4 hours. After cooling, copolyester product 5 was obtained.

[0036] Example 6 Terephthalic acid (PTA), monoethoxylated tricyclodecanediethanol (TCDDMEO), and 1,4-cyclohexanediethanol (CHDM) were added to a reactor at a molar ratio of PTA to TCDDMEO and CHDM of 1:0.65:0.65. The system was purged under a nitrogen atmosphere, and 0.1 mol% of zinc acetate catalyst (PTA molar amount) was added. The mixture was then stirred and heated to 180°C for esterification for 4 hours. Next, 0.12 mol% of antimony glycolate (PTA molar amount) and 0.05 mol% of triphenyl phosphate stabilizer were added, followed by heating to 240°C and a pressure of 80 Pa for polycondensation reaction for 4 hours. After cooling, copolyester product 6 was obtained.

[0037] Example 7 Terephthalic acid (PTA), tricyclodecanedicarboxylic acid (TCD-DA), monoethoxylated tricyclodecanediethanol (TCDDMEO), and 1,4-cyclohexanediethanol (CHDM) were added to a reactor. The molar ratio of PTA to TCD-DA was 0.5:0.5, and the molar ratio of TCDDMEO to CHDM was 0.65:0.65. The system was purged under a nitrogen atmosphere. Zinc acetate catalyst (0.1 mol% of the total molar amount of PTA and TCD-DA) was added, and the mixture was stirred and heated to 180°C for esterification reaction for 4 hours. Then, antimony glycolate (0.12 mol% of the total molar amount of PTA and TCD-DA) and triphenyl phosphate stabilizer (0.05 mol% of the total molar amount of triphenyl phosphate) were added, and the mixture was heated to 240°C and polycondensed at 80 Pa for 4 hours. After cooling, copolyester product 7 was obtained.

[0038] Example 8 Isophthalic acid (IPA), tricyclodecanediethanol (TCDDM), and monoethoxylated tricyclodecanediethanol (TCDDMEO) were added to a reactor at a molar ratio of IPA to TCDDM and TCDDMEO of 1:0.35:0.85. The system was replaced with a nitrogen atmosphere. 0.008 mol% of IPA was added as a catalyst, tetrabutyl titanate, and the mixture was stirred and heated to 180°C for esterification for 4 hours. Then, 0.12 mol% of IPA was added as antimony glycolate and 0.05 mol% as a stabilizer, triphenyl phosphate. The mixture was heated to 240°C and polycondensed at 80 Pa for 4 hours. After cooling, copolyester product 8 was obtained.

[0039] Example 9 Terephthalic acid (PTA), monoethoxylated tricyclodecanediethanol (TCDDMEO), and 1,4-butanediol (BDO) were added to a reactor at a molar ratio of PTA to TCDDMEO and BDO of 1:0.65:0.65. The system was purged under a nitrogen atmosphere. Zinc acetate catalyst (0.1 mol% of PTA) was added, and the mixture was stirred and heated to 180°C for esterification reaction for 4 hours. Antimony glycolate (0.12 mol% of PTA) and triphenyl phosphate stabilizer (0.05 mol% of PTA) were then added, and the mixture was heated to 240°C and subjected to polycondensation at 80 Pa for 4 hours. The mixture was then cooled to obtain copolyester product 9.

[0040] Example 10 Terephthalic acid (PTA), monoethoxylated tricyclodecanediethanol (TCDDMEO), and isosorbide were added to a reactor at a molar ratio of PTA to TCDDMEO and isosorbide of 1:0.7:0.6. The system was purged under a nitrogen atmosphere, and 0.1 mol% of PTA as a catalyst (zinc acetate) was added. The mixture was stirred and heated to 180°C for 4 hours for esterification. Then, 0.12 mol% of PTA as antimony glycolate and 0.05 mol% as a stabilizer (phosphorous acid) were added, and the mixture was heated to 240°C and subjected to polycondensation at 80 Pa for 4 hours. The mixture was then cooled to obtain copolyester product 10.

[0041] Performance testing: (1) Determination of glass transition temperature (Tg): The copolyester samples were tested using differential scanning calorimetry (DSC). Test conditions: nitrogen atmosphere, heating rate of 10℃ / min, temperature scan range of -50℃ to 300℃. The midpoint of the step transition in the second heating scan curve was taken as the glass transition temperature.

[0042] (2) Transmittance measurement: The test was conducted in accordance with GB / T 2410-2008 standard.

[0043]

[0044] Test results show that the glass transition temperature of the alicyclic copolyester prepared by this invention is between 82℃ and 102℃, and the light transmittance is between 88% and 91%, indicating that the copolyester possesses both high transparency and high heat resistance. Comparing different dicarboxylic acid systems, the pure TCD-DA system has slightly higher light transmittance (89%-91%), while the pure PTA system can reach a maximum Tg of 102℃; the mixed acid system (PTA+TCD-DA) and the IPA system also achieve good overall performance. Increasing the degree of ethoxylation has little effect on light transmittance; the Tg decreases slightly but remains above 86℃. After introducing other diols such as CHDM, BDO, or isosorbide, the Tg of the copolyester is between 81℃ and 94℃, and the light transmittance is not lower than 88%. The high-transparency alicyclic copolyester provided by this invention maintains high transparency and high heat resistance while possessing good compositional adjustability, making it suitable for food packaging, baby bottles, water cups, optical films, and medical devices.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A highly transparent alicyclic copolyester, characterized in that, The copolyester comprises tricyclodecanediol units and dicarboxylic acid units; The tricyclic decanediol unit is at least one of the following structures: The dicarboxylic acid unit is at least one of tricyclic decanedicarboxylic acid and aromatic dicarboxylic acid.

2. The high-transparency alicyclic copolyester according to claim 1, characterized in that, The tricyclic decanedicarboxylic acid has the following structure: 。 3. The high-transparency alicyclic copolyester according to claim 1, characterized in that, The aromatic dicarboxylic acid is at least one of terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid.

4. The high-transparency alicyclic copolyester according to claim 1, characterized in that, The copolyester further comprises at least one of 1,4-cyclohexanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, isosorbide, and 1,6-hexanediol.

5. The high-transparency alicyclic copolyester according to claim 1, characterized in that, The molar ratio of the dicarboxylic acid component to the diol component in the copolyester is 1:1 to 1:1.

5.

6. A method for preparing a highly transparent alicyclic copolyester according to any one of claims 1-5, characterized in that, Includes the following steps: (1) The dicarboxylic acid component, the diol component and the catalyst are mixed and esterified at 170℃~250℃ to obtain the esterification intermediate; (2) Add a catalyst and a phosphorus stabilizer to the esterification intermediate obtained in step (1) and carry out a polycondensation reaction to obtain the high transparency alicyclic copolyester.

7. The method for preparing the high-transparency alicyclic copolyester according to claim 6, characterized in that, The catalyst is selected from at least one of titanium-based catalysts, antimony-based catalysts, tin-based catalysts, and germanium-based catalysts.

8. The method for preparing the high-transparency alicyclic copolyester according to claim 6, characterized in that, The phosphorus stabilizer is selected from at least one of trimethyl phosphate, triphenyl phosphate, phosphorous acid, hypophosphite, triisooctyl phosphite, and triphenyl phosphite.

9. The method for preparing the high-transparency alicyclic copolyester according to claim 6, characterized in that, The polycondensation reaction conditions in step (2) are: vacuum degree 10Pa~200Pa, temperature 250℃~280℃.

10. The use of the highly transparent alicyclic copolyester according to any one of claims 1-5 in food packaging materials, baby bottles, water cups, optical films or medical devices.

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