Highly transparent light-colored heat-resistant copolyester and method for preparing the same
By adding licorice antioxidants and rosemary extract during the preparation of copolyester, the crystal structure was adjusted, solving the problems of low transparency and poor color of transparent heat-resistant copolyester at high temperatures, and achieving high light transmittance and good heat resistance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WANHUA CHEM GRP CO LTD
- Filing Date
- 2024-10-28
- Publication Date
- 2026-07-10
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polyester, specifically relating to a high-transparency, light-colored, heat-resistant copolyester and its preparation method. Background Technology
[0002] Poly(1,4-cyclohexanediethanol) terephthalate (PCT) is a high-performance, transparent, heat-resistant copolyester resin. It is obtained through esterification-condensation polymerization of terephthalic acid (PTA) and 1,4-cyclohexanediethanol (CHDM), or through transesterification-condensation polymerization of dimethyl terephthalate (DMT) and 1,4-cyclohexanediethanol (CHDM). PCT is characterized by its high melting point and rapid crystallization rate, resulting in an opaque material. To reduce the crystallization rate and melting point of PCT and obtain a colorless, transparent, heat-resistant material, it is typically copolymerized with other diol monomers, such as 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO), neopentyl glycol (NPG), and ethylene glycol (EG). These copolymers inhibit PCT crystallization, leading to transparent products. The copolyester obtained by copolymerizing with CBDO is not only transparent but also possesses a high glass transition temperature and good impact resistance, making it widely applicable in water cups, electronic cigarettes, and small household appliances.
[0003] The differences in crystal structure at the microscale during the melt polycondensation process of copolyesters are one of the reasons affecting the light transmittance of copolyesters. Furthermore, insufficient thermal stability makes them prone to side reactions and color formation at high temperatures, affecting the product's hue. During the synthesis of CN101300285A copolyester, without the addition of stabilizers, the melt surface is very unstable, and excessive foaming and bubbling result in a high porosity in the melt. CN101300285A copolyesters tend to have a yellowish tint, and even with the addition of stabilizers, a light yellow product may still be obtained.
[0004] In summary, transparent heat-resistant copolyesters still suffer from low light transmittance and poor color, which urgently need to be addressed. Summary of the Invention
[0005] One of the objectives of this invention is to address the problems of low transparency, high haze, poor thermal stability, and easy occurrence of side reactions and color formation in existing copolyesters at high temperatures. This invention provides a method for preparing a high-transparency, light-colored, heat-resistant copolyester that can adjust the crystal structure of the copolyester reactants, improve the light transmittance and reduce the haze, and weaken the effects of side reactions at high temperatures, thereby reducing the color formation problem.
[0006] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows:
[0007] A method for preparing a copolyester, the method comprising the following steps:
[0008] S1: The diacid is esterified with a diol, and / or the dimethyl ester of the diacid is transesterified with a diol to obtain the esterified product and / or the transesterified product.
[0009] S2: Esterification reaction of esters and / or transesterifications to obtain prepolymers;
[0010] S3: The prepolymer undergoes a final polycondensation reaction to obtain the target copolyester;
[0011] In S1, a combination of licorice antioxidant and rosemary extract is added for esterification and / or transesterification.
[0012] The inventors modified the copolyester crystal structure by adding a combination of licorice antioxidant and rosemary extract during the esterification or transesterification stage of the reaction, thereby reducing side reactions at high temperatures during copolyester synthesis, and achieving the goals of improving light transmittance, color, heat resistance, and processing performance.
[0013] In one embodiment of the present invention, the dicarboxylic acid or dimethyl ester of the dicarboxylic acid in S1 is a C6-C20 dicarboxylic acid, preferably one or more of terephthalic acid or its dimethyl ester, isophthalic acid or its dimethyl ester, phthalic acid or its dimethyl ester, biphenyl dicarboxylic acid or its dimethyl ester, naphthalenedicarboxylic acid or its dimethyl ester, furanic acid or its dimethyl ester, thiophene dicarboxylic acid or its dimethyl ester, and cyclohexanedicarboxylic acid or its dimethyl ester, more preferably terephthalic acid or its dimethyl ester, and / or isophthalic acid or its dimethyl ester.
[0014] In one embodiment of the present invention, the diol in S1 is a C2-C20 aliphatic diol and / or aromatic diol, preferably 1,4-cyclohexanediol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, isosorbide, ethylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 2,3-butanediol, 1,2-pentanediol, 1,4-pentanediol, 1,5-pentanediol, neopentanediol, 3- One or more of methyl 1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, diethylene glycol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, spirocyclodiol, and tricyclodecanediethanol, more preferably 1,4-cyclohexanediethanol and / or 2,2,4,4-tetramethyl-1,3-cyclobutanediol; preferably, the molar ratio of the diol to the diacid or the diester of the diacid is (1.1-1.5):1, more preferably (1.2-1.4):1.
[0015] In one embodiment of the present invention, the licorice antioxidant in S1 is glycyrrhizin and / or glycyrrhizin, and the rosemary extract is sarsaparilla acid and / or sarsaparilla phenol; preferably, the mass ratio of the licorice antioxidant to the rosemary extract is (0.1-10):1, more preferably (0.5-3):1; preferably, the composition of the licorice antioxidant and rosemary extract is 100-300 ppm of the total mass of diol and diacid and / or diester of diacid, more preferably 200-300 ppm.
[0016] In one embodiment of the present invention, S1 is the addition of a catalyst; preferably, the catalyst is one or more of the following: dibutyltin oxide, dimethyltin oxide, monobutyltriisooctanoate, dibutyldimethoxytin, stannous octanoate, stannous oxalate, dibutyltin diacetate, dibutyltin dilaurate, tetrabutyl titanate, isopropyl titanate, titanium glycolate, lithium acetate, potassium acetate, calcium acetate, magnesium acetate, barium acetate, zinc acetate, cobalt acetate, antimony acetate, lead acetate, and manganese acetate, preferably dibutyltin oxide and / or tetrabutyl titanate; preferably, the catalyst is 200-500 ppm by mass of the total mass of the diol and diacid and / or diacid diester, preferably 300-400 ppm. The above-mentioned additives and their dosages are commonly selected and used in the art.
[0017] In one embodiment of the present invention, a heat stabilizer is added in step S1; preferably, the heat stabilizer is a phosphate ester compound, more preferably an alkyl phosphate ester and / or an aryl phosphate ester, and more preferably a triphenyl phosphate ester and / or a triethyl phosphate ester; preferably, the heat stabilizer is 300-600 ppm of the total mass of the diol and diacid and / or the diester of the diacid, more preferably 300-400 ppm. The above-mentioned additives and their dosages are commonly used selections and dosages in the art.
[0018] In one embodiment of the present invention, the reaction temperature of S1 is 190-240°C, preferably 210-230°C, and the reaction time is 120-240 min, preferably 150-180 min.
[0019] In one embodiment of the present invention, the reaction temperature in S2 is 240-260°C, preferably 240-250°C, the absolute pressure of the reaction is 1-3 kPa, preferably 1-2 kPa, and the reaction time is 30-60 min, preferably 40-50 min.
[0020] In one embodiment of the present invention, the reaction temperature in S3 is 250-270°C, preferably 260-265°C, the absolute pressure of the reaction is less than 100 Pa, preferably less than 50 Pa, and the reaction time is 120-300 min, preferably 150-210 min.
[0021] Another object of the present invention is to provide a copolyester.
[0022] A copolyester, wherein the copolyester is prepared by the above-described preparation method, and the copolyester is a high-transparency, light-colored, heat-resistant copolyester.
[0023] In one embodiment of the present invention, the copolyester has an intrinsic viscosity > 0.6 dL / g, a tensile strength of injection-molded specimens > 40 MPa, a light transmittance of optical specimens > 90%, a haze < 1%, a color difference L value > 90, an absolute value of a value < 1, and an absolute value of b value < 1; after the granules are heated at 260-280°C for 10 min, the tensile strength Δ of injection-molded specimens is < 2 MPa, and the color difference Δb value of optical specimens is < 0.2.
[0024] Compared with the prior art, the positive effects of the technical solution of the present invention are as follows:
[0025] (1) The preparation method of the present invention can adjust the crystal structure of the copolyester and improve the light transmittance of the copolyester.
[0026] (2) The preparation method of the present invention can reduce the effect of side reactions at high temperature during copolyester synthesis and improve the color of copolyester;
[0027] (3) The copolyester prepared by the preparation method of the present invention has good heat resistance and processing performance. After heating at 260-280℃ for 30 minutes, the tensile strength and color difference of the injection molded sample are well maintained. Detailed Implementation
[0028] The present invention will be further described below with reference to specific embodiments. It should be noted that the embodiments are only used to illustrate the present invention and do not constitute a limitation on the scope of protection of the present invention.
[0029] The raw materials—diols, diacids or their dimethyl esters, catalysts, heat stabilizers, licorice antioxidants, and rosemary extract composition—were all commercially available and of analytical grade. Dimethyl terephthalate, terephthalic acid, dimethyl thiophene dicarboxylate, cyclohexanedicarboxylic acid, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 1,4-cyclohexanediethanol, neopentyl glycol, ethylene glycol, isosorbide, spirocyclodiol, and tricyclodecanediethanol were purchased from Beijing Inocare Technology Co., Ltd., with a purity of 99%. Dibutyltin oxide, tetrabutyl titanate, titanium glycol, zinc acetate, triphenyl phosphate, and triethyl phosphate were purchased from Shanghai Maclean Biochemical Technology Co., Ltd., with a purity of 98%. Licorice flavonoids, glycyrrhizin, caryopsisic acid, and caryopsisol were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., with a purity of 98%.
[0030] The equipment and methods used in this invention are all common in the field.
[0031] Intrinsic viscosity: The intrinsic viscosity of the sample at 25℃ was measured using a Nanjing Tenghui Ubbelohde viscometer. The solvent was phenol / tetrachloroethane (mass ratio w / w = 3 / 2), and the sample concentration was 0.005 g / mL.
[0032] Mechanical properties: Tensile strength was tested using a HaakeMiniJet II micro injection molding machine to prepare dumbbell-shaped specimens with a width of 4 mm and a thickness of 2 mm. The specimens were tested using a mechanical testing machine (Instron 5960) at a tensile speed of 50 mm / min.
[0033] Optical performance: 25mm diameter and 1.5mm thick circular wafers were prepared using a Haake MiniJet II micro-injection molding machine. Transmittance and haze (H) were measured using a CS-821N benchtop spectrophotometer. Color difference was measured as L / a / b (representing brightness or black / white intensity, green / red intensity, and blue / yellow intensity, respectively).
[0034] Example 1
[0035] 1000g of dimethyl terephthalate, 295g of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 596g of 1,4-cyclohexanediol, 0.38g of dibutyltin oxide, 0.57g of triphenyl phosphate, 0.02g of glycyrrhizin, and 0.17g of oxalic acid were added to a reaction vessel and subjected to transesterification at atmospheric pressure and 240℃ for 120 min. The reaction vessel was then evacuated to 3kPa and reacted at 240℃ for 60 min. Finally, the reaction vessel was evacuated to 50Pa and reacted at 250℃ for 300 min to obtain copolyester 1. After water cooling and pelletizing, biodegradable copolyester pellets were obtained. The intrinsic viscosity was 0.641dL / g, the tensile strength of the injection-molded sample was 43MPa, the light transmittance was 92%, the haze was 0.7%, the color difference L value was 93, the a value was -0.5, and the absolute value of the b value was 0.7. After the granules were heated at 270℃ for 10 minutes, the tensile strength of the injection-molded sample was 42MPa, and the color difference b-value of the optical sample was 0.8.
[0036] Example 2
[0037] 1000g of dimethyl terephthalate, 295g of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 596g of 1,4-cyclohexanediol, 0.95g of dibutyltin oxide, 1.14g of triphenyl phosphate, 0.52g of glycyrrhizin, and 0.05g of oxalic acid were added to a reaction vessel and subjected to transesterification at atmospheric pressure and 190℃ for 240 min. The reaction vessel was then evacuated to 1kPa and reacted at 260℃ for 30 min. Finally, the reaction vessel was evacuated to 100Pa and reacted at 270℃ for 120 min to obtain copolyester 2. After water cooling and pelletizing, biodegradable copolyester pellets were obtained. The intrinsic viscosity was 0.648dL / g, the tensile strength of the injection-molded sample was 44MPa, the light transmittance was 92%, the haze was 0.6%, the color difference L value was 94, the a value was -0.5, and the absolute value of the b value was 0.7. After the granules were heated at 270℃ for 10 minutes, the tensile strength of the injection-molded sample was 43 MPa, and the color difference b-value of the optical sample was 0.8.
[0038] Example 3
[0039] 1000g of dimethyl terephthalate, 295g of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 596g of 1,4-cyclohexanediol, 0.57g of dibutyltin oxide, 0.57g of triphenyl phosphate, 0.13g of glycyrrhizin, and 0.25g of oxalic acid were added to a reaction vessel and subjected to transesterification at atmospheric pressure and 210℃ for 150 min. The reaction vessel was then evacuated to 2kPa and reacted at 250℃ for 40 min. Finally, the reaction vessel was evacuated to 50Pa and reacted at 260℃ for 150 min to obtain copolyester 3. After water cooling and pelletizing, biodegradable copolyester pellets were obtained. The intrinsic viscosity was 0.652dL / g, the tensile strength of the injection-molded sample was 46MPa, the light transmittance was 93%, the haze was 0.5%, the color difference L value was 95, the a value was -0.3, and the absolute value of the b value was 0.5. After the granules were heated at 270℃ for 10 minutes, the tensile strength of the injection-molded sample was 45MPa, and the color difference b-value of the optical sample was 0.5.
[0040] Example 4
[0041] 1000g of dimethyl terephthalate, 295g of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 596g of 1,4-cyclohexanediol, 0.76g of dibutyltin oxide, 0.76g of triphenyl phosphate, 0.13g of glycyrrhizin, and 0.25g of oxalic acid were added to a reaction vessel and subjected to transesterification at atmospheric pressure and 230℃ for 180min. The reaction vessel was then evacuated to 2kPa and reacted at 250℃ for 50min. The reaction vessel was then evacuated to 50Pa and reacted at 265℃ for 210min to obtain copolyester 4. After water cooling and pelletizing, biodegradable copolyester pellets were obtained. The intrinsic viscosity was 0.651dL / g, the tensile strength of the injection-molded sample was 45MPa, the light transmittance was 92%, the haze was 0.6%, the color difference L value was 94, the a value was -0.3, and the absolute value of the b value was 0.6. After the granules were heated at 270℃ for 10 minutes, the tensile strength of the injection-molded sample was 44 MPa, and the color difference b-value of the optical sample was 0.7.
[0042] Example 5
[0043] 1000g of dimethyl terephthalate, 223g of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 594g of 1,4-cyclohexanediol, 0.57g of dibutyltin oxide, 0.57g of triphenyl phosphate, 0.13g of glycyrrhizin, and 0.25g of oxalic acid were added to a reaction vessel and subjected to transesterification at atmospheric pressure and 210℃ for 150 min. The reaction vessel was then evacuated to 2kPa and reacted at 260℃ for 40 min. The evacuation was then repeated to 50Pa and reacted at 260℃ for 150 min to obtain copolyester 5. After water cooling and pelletizing, biodegradable copolyester pellets were obtained. The intrinsic viscosity was 0.651dL / g, the tensile strength of the injection-molded sample was 45MPa, the light transmittance was 93%, the haze was 0.5%, the color difference L value was 94, the a value was -0.3, and the absolute value of the b value was 0.6. After the granules were heated at 270℃ for 10 minutes, the tensile strength of the injection-molded sample was 44 MPa, and the color difference b-value of the optical sample was 0.6.
[0044] Example 6
[0045] 1000g of dimethyl terephthalate, 520g of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 594g of 1,4-cyclohexanediol, 0.57g of dibutyltin oxide, 0.57g of triphenyl phosphate, 0.13g of glycyrrhizin, and 0.25g of oxalic acid were added to a reaction vessel and subjected to transesterification at atmospheric pressure and 210℃ for 150 min. The reaction vessel was then evacuated to 2kPa and reacted at 250℃ for 40 min. Finally, the reaction vessel was evacuated to 50Pa and reacted at 260℃ for 150 min to obtain copolyester 6. After water cooling and pelletizing, biodegradable copolyester pellets were obtained. The intrinsic viscosity was 0.648dL / g, the tensile strength of the injection-molded sample was 44MPa, the light transmittance was 92%, the haze was 0.6%, the color difference L value was 94, the a value was -0.4, and the absolute value of the b value was 0.6. After the granules were heated at 270℃ for 10 minutes, the tensile strength of the injection-molded sample was 43 MPa, and the color difference b-value of the optical sample was 0.7.
[0046] Example 7
[0047] 856g of terephthalic acid, 295g of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 596g of 1,4-cyclohexanediol, 0.57g of tetrabutyl titanate, 0.57g of triethyl phosphate, 0.13g of glycyrrhizin, and 0.25g of caryophyllene were added to a reaction vessel and esterified at atmospheric pressure and 210℃ for 150 min. The reaction vessel was then evacuated to 2kPa and reacted at 250℃ for 40 min. Finally, the reaction vessel was evacuated to 50Pa and reacted at 260℃ for 150 min to obtain copolyester 7. After water cooling and pelletizing, biodegradable copolyester pellets were obtained. The intrinsic viscosity was 0.650 dL / g, the tensile strength of the injection-molded sample was 45 MPa, the light transmittance was 92%, the haze was 0.5%, the color difference L value was 94, the a value was -0.4, and the absolute value of the b value was 0.6. After the granules were heated at 270℃ for 10 minutes, the tensile strength of the injection-molded sample was 44 MPa, and the color difference b-value of the optical sample was 0.6.
[0048] Example 8
[0049] 1031g of dimethyl thiophene dicarboxylate, 213g of neopentyl glycol, 596g of 1,4-cyclohexanediethanol, 0.57g of monobutyltriisooctanoate, 0.57g of triphenyl phosphate, 0.13g of glycyrrhizin, and 0.25g of caryophyllene were added to a reaction vessel and subjected to transesterification at atmospheric pressure and 210℃ for 150 min. The reaction vessel was then evacuated to 2kPa and reacted at 250℃ for 40 min. Finally, the reaction vessel was evacuated to 50Pa and reacted at 260℃ for 150 min to obtain copolyester 8. After water cooling and pelletizing, biodegradable copolyester pellets were obtained. The intrinsic viscosity was 0.632dL / g, the tensile strength of the injection-molded sample was 42MPa, the light transmittance was 91%, the haze was 0.9%, the color difference L value was 92, the a value was -0.8, and the absolute value of the b value was 0.8. After the granules were heated at 270℃ for 10 minutes, the tensile strength of the injection-molded sample was 41 MPa, and the color difference b-value of the optical sample was 0.9.
[0050] Example 9
[0051] 887g of cyclohexanedicarboxylic acid, 213g of neopentyl glycol, 257g of ethylene glycol, 0.57g of tetrabutyl titanate, 0.57g of triphenyl phosphate, 0.13g of glycyrrhizin, and 0.25g of oxalic acid were added to a reaction vessel and subjected to transesterification at atmospheric pressure and 210℃ for 150 min. The reaction vessel was then evacuated to 2kPa and reacted at 250℃ for 40 min. Finally, the evacuation was reduced to 50Pa and reacted at 260℃ for 150 min to obtain copolyester 9. After water cooling and pelletizing, biodegradable copolyester pellets were obtained. The intrinsic viscosity was 0.617 dL / g, the tensile strength of the injection-molded sample was 41 MPa, the light transmittance was 91%, the haze was 0.8%, the color difference L value was 91, the a value was -0.7, and the absolute value of the b value was 0.9. After heating the pellets at 270℃ for 10 min, the tensile strength of the injection-molded sample was 40 MPa, and the color difference b value of the optical sample was 1.0.
[0052] Example 10
[0053] 1000g of dimethyl terephthalate, 299g of isosorbide, 596g of 1,4-cyclohexanediethanol, 0.57g of dibutyltin oxide, 0.57g of triethyl phosphate, 0.13g of glycyrrhizin, and 0.25g of oxalic acid were added to a reaction vessel and subjected to transesterification at atmospheric pressure and 210℃ for 150 min. The reaction vessel was then evacuated to 2kPa and reacted at 250℃ for 40 min. Finally, the reaction vessel was evacuated to 50Pa and reacted at 260℃ for 150 min to obtain copolyester 10. After water cooling and pelletizing, biodegradable copolyester pellets were obtained. The intrinsic viscosity was 0.625dL / g, the tensile strength of the injection-molded sample was 41MPa, the light transmittance was 91%, the haze was 0.8%, the color difference L value was 92, the a value was -0.9, and the absolute value of the b value was 0.9. After the granules were heated at 270℃ for 10 minutes, the tensile strength of the injection-molded sample was 40MPa, and the color difference b-value of the optical sample was 0.9.
[0054] Example 11
[0055] 856g of terephthalic acid, 127g of ethylene glycol, 1258g of spirocyclic glycol, 0.57g of titanium glycol, 0.57g of triphenyl phosphate, 0.13g of glycyrrhizin, and 0.25g of oxalic acid were added to a reactor and subjected to transesterification at atmospheric pressure and 210℃ for 150 min. The reactor was then evacuated to 2 kPa and reacted at 250℃ for 40 min. Finally, the reactor was evacuated to 50 Pa and reacted at 260℃ for 150 min to obtain copolyester 11. After water cooling and pelletizing, biodegradable copolyester pellets were obtained. The intrinsic viscosity was 0.631 dL / g, the tensile strength of the injection-molded sample was 42 MPa, the light transmittance was 92%, the haze was 0.8%, the color difference L value was 91, the a value was -0.8, and the absolute value of the b value was 0.8. After heating the pellets at 270℃ for 10 min, the tensile strength of the injection-molded sample was 42 MPa, and the color difference b value of the optical sample was 0.8.
[0056] Example 12
[0057] 856g of dimethyl terephthalate, 127g of ethylene glycol, 811g of tricyclodecanediethanol, 0.57g of zinc acetate, 0.57g of triphenyl phosphate, 0.13g of glycyrrhizin, and 0.25g of oxalic acid were added to a reaction vessel and subjected to transesterification at atmospheric pressure and 210℃ for 150 min. The reaction vessel was then evacuated to 2kPa and reacted at 250℃ for 40 min. Finally, the reaction vessel was evacuated to 50Pa and reacted at 260℃ for 150 min to obtain copolyester 12. After water cooling and pelletizing, biodegradable copolyester pellets were obtained. The intrinsic viscosity was 0.628dL / g, the tensile strength of the injection-molded sample was 42MPa, the light transmittance was 91%, the haze was 0.9%, the color difference L value was 92, the a value was -0.7, and the absolute value of the b value was 0.9. After the granules were heated at 270℃ for 10 minutes, the tensile strength of the injection-molded sample was 41 MPa, and the color difference b-value of the optical sample was 1.0.
[0058] Comparative Example 1
[0059] Compared with Example 3, the only difference is that sarsaparilla acid is not added.
[0060] 1000g of dimethyl terephthalate, 295g of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 596g of 1,4-cyclohexanediol, 0.57g of dibutyltin oxide, 0.57g of triphenyl phosphate, and 0.13g of glycyrrhizin were added to a reaction vessel and subjected to transesterification at atmospheric pressure and 210℃ for 150 min. The reaction vessel was then evacuated to 2kPa and reacted at 250℃ for 40 min. Finally, the reaction vessel was evacuated to 50Pa and reacted at 260℃ for 150 min to obtain copolyester 13. After water cooling and pelletizing, biodegradable copolyester pellets were obtained. The intrinsic viscosity was 0.647dL / g, the tensile strength of the injection-molded sample was 45MPa, the light transmittance was 91%, the haze was 0.8%, the color difference L value was 93, the a value was -0.6, and the absolute value of the b value was 0.8. After the granules were heated at 270℃ for 10 minutes, the tensile strength of the injection-molded sample was 43 MPa, and the color difference b-value of the optical sample was 1.0.
[0061] Comparative Example 2
[0062] Compared with Example 3, the only difference is that licorice flavonoids are not added.
[0063] 1000g of dimethyl terephthalate, 295g of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 596g of 1,4-cyclohexanediol, 0.57g of dibutyltin oxide, 0.57g of triphenyl phosphate, and 0.25g of oxalic acid were added to a reaction vessel and subjected to transesterification at atmospheric pressure and 210℃ for 150 min. The reaction vessel was then evacuated to 2kPa and reacted at 250℃ for 40 min. Finally, the reaction vessel was evacuated to 50Pa and reacted at 260℃ for 150 min to obtain copolyester 14. After water cooling and pelletizing, biodegradable copolyester pellets were obtained. The intrinsic viscosity was 0.646dL / g, the tensile strength of the injection-molded sample was 44MPa, the light transmittance was 91%, the haze was 0.8%, the color difference L value was 93, the a value was -0.6, and the absolute value of the b value was 0.8. After the granules were heated at 270℃ for 10 minutes, the tensile strength of the injection-molded sample was 42MPa, and the color difference b-value of the optical sample was 1.0.
[0064] Comparative Example 3
[0065] Compared with Example 3, the only difference is that oxalic acid and glycyrrhizin are not added.
[0066] 1000g of dimethyl terephthalate, 295g of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 596g of 1,4-cyclohexanediol, 0.57g of dibutyltin oxide, and 0.57g of triphenyl phosphate were added to a reaction vessel and subjected to transesterification at atmospheric pressure and 210℃ for 150 min. The reaction vessel was then evacuated to 2kPa and reacted at 250℃ for 40 min. Finally, the reaction vessel was evacuated to 50Pa and reacted at 260℃ for 150 min to obtain copolyester 15. After water cooling and pelletizing, biodegradable copolyester pellets were obtained. The intrinsic viscosity was 0.647dL / g, the tensile strength of the injection-molded sample was 45MPa, the light transmittance was 90%, the haze was 0.9%, the color difference L value was 92, the a value was -0.7, and the absolute value of the b value was 0.9. After the granules were heated at 270℃ for 10 minutes, the tensile strength of the injection-molded sample was 41 MPa, and the color difference b-value of the optical sample was 1.2.
[0067] Comparative Example 4
[0068] Compared with Example 7, the only difference is that sarsaparilla acid and glycyrrhizin are not added.
[0069] 856g of terephthalic acid, 295g of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 596g of 1,4-cyclohexanediol, 0.57g of tetrabutyl titanate, and 0.57g of triethyl phosphate were added to a reaction vessel and subjected to transesterification reaction at atmospheric pressure and 210℃ for 150 min. The reaction vessel was then evacuated to 2 kPa and reacted at 250℃ for 40 min. Finally, the reaction vessel was evacuated to 50 Pa and reacted at 260℃ for 150 min to obtain copolyester 16. After water cooling and pelletizing, biodegradable copolyester pellets were obtained. The intrinsic viscosity was 0.645 dL / g, the tensile strength of the injection-molded sample was 45 MPa, the light transmittance was 90%, the haze was 0.9%, the color difference L value was 91, the a value was -0.8, and the absolute value of the b value was 0.8. After the granules were heated at 270℃ for 10 minutes, the tensile strength of the injection-molded sample was 40MPa, and the color difference b value of the optical sample was 1.1.
[0070] It is readily understood that the above embodiments are merely illustrative examples for clear explanation and do not imply that the invention is limited thereto. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom remain within the scope of protection of this invention.
Claims
1. A method for preparing a copolyester, characterized in that, The preparation method includes the following steps: S1: The diacid is esterified with a diol, and / or the dimethyl ester of the diacid is transesterified with a diol to obtain the esterified product and / or the transesterified product. S2: Esterification reaction of esters and / or transesterifications to obtain prepolymers; S3: The prepolymer undergoes a final polycondensation reaction to obtain the target copolyester; In S1, a combination of licorice antioxidant and rosemary extract is added for esterification and / or transesterification.
2. The preparation method according to claim 1, characterized in that, The dicarboxylic acid or dimethyl ester of the dicarboxylic acid mentioned in S1 is a C6-C20 dicarboxylic acid; And / or, the diol in S1 is a C2-C20 aliphatic diol and / or an aromatic diol; And / or, the licorice antioxidants in S1 are glycyrrhizin and / or glycyrrhizin, and the rosemary extract is caryopsisic acid and / or caryopsisol; And / or, S1 is added to the catalyst; And / or, S1 is added with a heat stabilizer; And / or, the reaction temperature of S1 is 190-240℃, and the reaction time is 120-240 min.
3. The preparation method according to claim 2, characterized in that, S1 The dicarboxylic acid or dimethyl ester of the dicarboxylic acid is selected from one or more of the following: terephthalic acid or its dimethyl ester, isophthalic acid or its dimethyl ester, phthalic acid or its dimethyl ester, biphenyl dicarboxylic acid or its dimethyl ester, naphthalic acid or its dimethyl ester, furan dicarboxylic acid or its dimethyl ester, thiophene dicarboxylic acid or its dimethyl ester, and cyclohexane dicarboxylic acid or its dimethyl ester. And / or, the diol in S1 is one or more of the following: 1,4-cyclohexanediol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, isosorbide, ethylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 2,3-butanediol, 1,2-pentanediol, 1,4-pentanediol, 1,5-pentanediol, neopentanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, diethylene glycol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, spirocyclodiol, and tricyclodecanediol; The molar ratio of the diol to the diacid or the dimethyl ester of the diacid in S1 is (1.1-1.5):1; The mass ratio of licorice antioxidant to rosemary extract in S1 is (0.1-10):1; The licorice antioxidant and rosemary extract composition described in S1 is 100-300 ppm of the total mass of diol and diacid and / or dimethyl ester of diacid; The catalyst described in S1 is one or more of the following: dibutyltin oxide, dimethyltin oxide, monobutyltriisooctanoate, dibutyldimethoxytin, stannous octanoate, stannous oxalate, dibutyltin diacetate, dibutyltin dilaurate, tetrabutyl titanate, isopropyl titanate, titanium glycolate, lithium acetate, potassium acetate, calcium acetate, magnesium acetate, barium acetate, zinc acetate, cobalt acetate, antimony acetate, lead acetate, and manganese acetate. The catalyst mentioned in S1 is 200-500 ppm of the total mass of diol and diacid and / or dimethyl ester of diacid. The heat stabilizer mentioned in S1 is a phosphate ester compound; The heat stabilizer mentioned in S1 is 300-600 ppm of the total mass of diol and diacid and / or dimethyl ester of diacid. And / or, the reaction temperature of S1 is 210-230℃, and the reaction time is 150-180 min.
4. The preparation method according to claim 3, characterized in that, The dicarboxylic acid or dimethyl ester of the dicarboxylic acid mentioned in S1 is terephthalic acid or its dimethyl ester, and / or isophthalic acid or its dimethyl ester; And / or, the diol in S1 is 1,4-cyclohexanediethanol and / or 2,2,4,4-tetramethyl-1,3-cyclobutanediol; The molar ratio of the diol to the diacid or the dimethyl ester of the diacid in S1 is (1.2-1.4):1; The mass ratio of licorice antioxidant to rosemary extract in S1 is (0.5-3):1; The licorice antioxidant and rosemary extract composition described in S1 is 200-300 ppm of the total mass of diol and diacid and / or dimethyl ester of diacid; The catalyst described in S1 is dibutyltin oxide and / or tetrabutyl titanate; The catalyst mentioned in S1 is 300-400 ppm of the total mass of diol and diacid and / or dimethyl ester of diacid. The heat stabilizer mentioned in S1 is an alkyl phosphate ester and / or an aryl phosphate ester; The heat stabilizer mentioned in S1 is 300-400 ppm of the total mass of diol and diacid and / or dimethyl ester of diacid.
5. The preparation method according to claim 4, characterized in that, The heat stabilizer mentioned in S1 is triphenyl phosphate and / or triethyl phosphate.
6. The preparation method according to claim 1, characterized in that, The reaction temperature in S2 is 240-260℃, the absolute pressure is 1-3kPa, and the reaction time is 30-60min.
7. The preparation method according to claim 6, characterized in that, The reaction temperature in S2 is 240-250℃, the absolute pressure is 1-2 kPa, and the reaction time is 40-50 min.
8. The preparation method according to claim 1, characterized in that, The reaction temperature in S3 is 250-270℃, the absolute pressure is less than 100Pa, and the reaction time is 120-300min.
9. The preparation method according to claim 8, characterized in that, The reaction temperature in S3 is 260-265℃, the absolute pressure is less than 50Pa, and the reaction time is 150-210min.
10. A copolyester, wherein the copolyester is prepared by the preparation method according to any one of claims 1-9, and the copolyester is a high-transparency, light-colored, heat-resistant copolyester.
11. The copolyester according to claim 10, characterized in that, The copolyester has an intrinsic viscosity > 0.6 dL / g, a tensile strength of injection-molded specimens > 40 MPa, a light transmittance of optical specimens > 90%, a haze < 1%, a color difference L value > 90, an absolute value of a value < 1, and an absolute value of b value < 1. After the granules are heated at 260~280℃ for 10 min, the tensile strength Δ of injection-molded specimens is < 2 MPa, and the color difference Δb value of optical specimens is < 0.2.