A bottle grade modified petg chip and a method for preparing the same

Abstract

The application belongs to the technical field of polymer material preparation, and provides bottle-grade modified PETG chips and a preparation method thereof; first, a bisphenol fluorene compound is used as raw material to perform pre-activation in an alkaline catalyst and an aprotic polar solvent, then reacts with a carbonate to obtain 9,9-di(4-(2-hydroxyethoxy)phenyl)fluorene; meanwhile, a pyrimidine derivative is used to generate an active intermediate under the action of an activating agent, and then the intermediate is reacted with a three-carbon dihydric alcohol solution to obtain a urea-based pyrimidine ketone functional dihydric alcohol; then, the two additives are respectively prepared into functional master batches with bottle-grade PETG resin through a double-screw extruder; finally, the two functional master batches and base PETG resin are subjected to final melt blending extrusion granulation to obtain modified PETG chips; the application improves the heat resistance and toughness of PETG material by synergistically compounding an additive for providing rigid support and an additive for constructing a dynamic physical crosslinking network.

Description

Technical Field

[0001] This invention belongs to the field of polymer material preparation technology, and relates to a bottle-grade modified PETG chip and its preparation method. Background Technology

[0002] PETG (polyethylene terephthalate-1,4-cyclohexanediol) has been widely used in various fields due to its excellent transparency, good toughness, chemical resistance, and ease of processing. However, with the continuous expansion of application areas, especially in applications requiring hot filling or high-temperature sterilization, the insufficient heat resistance of standard bottle-grade PETG material has become a major bottleneck for its application upgrade. Its glass transition temperature is usually low, and it is prone to softening and deformation at high temperatures, limiting its use in packaging high-value-added products such as functional beverages and biological agents.

[0003] To improve the heat resistance of PETG, existing technologies typically employ copolymerization modification by introducing monomers with rigid structures. For example, introducing monomers containing benzene rings, naphthalene rings, or other rigid groups into the polymer backbone can effectively restrict the movement of molecular chain segments, thereby significantly increasing the glass transition temperature of the material. However, the sharp increase in molecular chain rigidity leads to a significant decrease in polymer flexibility, making the material brittle and severely deteriorating key toughness indicators such as impact resistance and elongation at break. Alternatively, PETG can be compounded with other high heat-resistant polymers (such as polycarbonate and polysulfone) through physical blending. However, this method often faces the problem of poor two-phase compatibility, resulting in decreased transparency and stratification of the blended material, making it difficult to meet the optical performance and stability requirements of bottle-grade materials. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a bottle-grade modified PETG chip and its preparation method. First, a rigid diol containing a fluorene ring structure and a ureidopyrimidinone functionalized diol capable of forming a dynamic hydrogen bond network are prepared. Then, these two functional additives are respectively made into masterbatches with PETG resin. Finally, the two masterbatches are melt-blended with the base resin to meet the needs of actual production.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing bottle-grade modified PETG chips, the method comprising:

[0007] S1, 9,9-bis(4-hydroxyphenyl)fluorene, potassium carbonate and anhydrous DMSO (dimethyl sulfoxide) are mixed and pre-activated, and then ethylene carbonate is added to react to obtain 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene;

[0008] S2, 2-amino-4-hydroxy-6-methylpyrimidine is dispersed in anhydrous THF (tetrahydrofuran), and 1,1'-carbonyldiimidazole is added for activation. The reaction yields an intermediate solution, which is then added dropwise to a Serinol solution to react and yield a ureidylpyrimidinone functionalized diol.

[0009] S3, bottle-grade PETG resin is dry-mixed with 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene and fed into a co-rotating twin-screw extruder to obtain masterbatch A;

[0010] S4, bottle-grade PETG resin is dry-mixed with ureidopyrimidinone functionalized diol and fed into a co-rotating twin-screw extruder to obtain masterbatch B;

[0011] S5, bottle-grade PETG resin, masterbatch A and masterbatch B are dry-mixed and fed into a co-rotating twin-screw extruder to obtain a bottle-grade modified PETG chip.

[0012] Specifically, it includes:

[0013] S1, 9,9-bis(4-hydroxyphenyl)fluorene, potassium carbonate and anhydrous DMSO were mixed, and the temperature was adjusted to the first temperature for pre-activation under a nitrogen atmosphere. Then ethylene carbonate was added and the temperature was adjusted to the second temperature for reaction. After the reaction was completed, the reaction solution was poured into ice water to precipitate, filtered and washed with deionized water to 6.8-7, filtered to remove water by pressure filtration, and then dissolved by heating under reflux in a mixed solvent. After hot filtration, cooling crystallization and drying were performed to obtain 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene;

[0014] S2, 2-amino-4-hydroxy-6-methylpyrimidine was dispersed in anhydrous THF under a nitrogen atmosphere. The temperature was adjusted to the first temperature and 1,1'-carbonyldiimidazole was added and stirred to activate the reaction. The temperature was adjusted to the third temperature to obtain an intermediate solution. The intermediate solution was added dropwise to Serinol solution under the first temperature condition. After the addition was complete, the reaction was stirred at room temperature. After the reaction was completed, the reaction solution was slowly poured into anhydrous n-hexane to precipitate. The solid was collected by suction filtration, redissolved in ethyl acetate and poured into n-hexane to precipitate again. The mixture was filtered and dried to obtain ureidopyrimidinone functionalized diol.

[0015] S3, bottle-grade PETG resin is dry-mixed with 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene and fed into a co-rotating twin-screw extruder, where it is extruded into water-cooled strands, dehydrated by an air knife, and pelletized to obtain masterbatch A;

[0016] S4, bottle-grade PETG resin is dry-mixed with ureidopyrimidinone functionalized diol and fed into a co-rotating twin-screw extruder, where it is extruded into water-cooled strands, dehydrated by air knife, and pelletized to obtain masterbatch B;

[0017] S5, bottle-grade PETG resin, masterbatch A and masterbatch B are dry-mixed and fed into a co-rotating twin-screw extruder for melt blending and granulation. After extrusion, water-cooled strips are formed, water is removed by air knife, and pellets are cut to obtain a bottle-grade modified PETG chip.

[0018] In step S1, the 9,9-bis(4-hydroxyphenyl)fluorene molecule contains two strongly acidic phenolic hydroxyl groups. Potassium carbonate, as a moderately strong base, in the aprotic polar solvent dimethyl sulfoxide (DMSO), has its carbonate ions that abstract protons from the phenolic hydroxyl groups, generating a highly reactive phenoxy anion. The pre-activation step, performed at low temperature, aims to ensure the acid-base reaction proceeds fully, forming a stable phenolic salt intermediate, while preventing premature side reactions in subsequent reactants. The subsequently added ethylene carbonate, as an electrophile, is a cyclic ester with significant ring strain. The previously generated phenoxy anion, acting as a strong nucleophile, attacks the methylene carbon atom bonded to the oxygen atom on the ethylene carbonate ring, causing ring-opening of the carbonate ring and forming an alkoxy anion intermediate. This intermediate then abstracts a proton from the solvent, ultimately introducing a hydroxyethoxy group. Since the 9,9-bis(4-hydroxyphenyl)fluorene molecule has two phenolic hydroxyl groups, the reaction will occur twice, thus attaching hydroxyethoxy groups to both ends of the molecule to generate the target product 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene.

[0019] In step S2, 2-amino-4-hydroxy-6-methylpyrimidine is a heterocyclic compound with multiple reaction sites. The added 1,1′-carbonyldiimidazole reacts with the amino and hydroxyl groups on the pyrimidine ring, but primarily preferentially reacts with the more acidic, enol or amide-form NH or OH groups to form a highly reactive acylimidazole or similar intermediate. This transforms the functional group on the pyrimidine ring into a leaving group that is more prone to nucleophilic addition. This reactive intermediate may undergo intramolecular rearrangement or further reactions. The solution of this intermediate containing the activated pyrimidine ring is added dropwise to a solution of Serinol (2-amino-1,3-propanediol). The Serinol molecule contains one primary amino group and two primary hydroxyl groups, with the primary amino group being far more nucleophilic than the hydroxyl groups. Therefore, the amino group of Serinol acts as a nucleophile, attacking the previously activated active site (e.g., the acyl carbon) generated by the 1,1′-carbonyldiimidazole, resulting in a nucleophilic acyl substitution reaction. The pyrimidinone core structure is linked to the Serinol molecule via a newly formed urea bond, with the imidazole moiety acting as a leaving group. Since the Serinol molecule retains two unreacted primary hydroxyl groups, the ureidopyrimidinone functionalized diol is a diol containing a ureidopyrimidinone group at one end and two hydroxyl groups at the other end.

[0020] In steps S3 and S4, the two functional additives are respectively mixed with base PETG resin in a twin-screw extruder to prepare masterbatches. Under the high temperature and strong shear conditions set in the extruder, both the PETG resin and the additives are in a molten state. PETG undergoes a limited transesterification reaction, particularly the terminal hydroxyl groups of ureidopyrimidinone functionalized diol and 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, which may react with the ester groups of the PETG molecular chain. This allows a small portion of the additive molecules to be covalently grafted to the ends or middle of the PETG backbone, which to some extent helps improve the compatibility of the additives with the matrix and prevents migration and exudation during subsequent processing or use.

[0021] Finally, in step S5, the two masterbatches are melt-blended and granulated with the base PETG resin. The core mechanism is to achieve the synergistic effect of the two functional additives at both the macroscopic and microscopic scales. During the final extrusion process, masterbatch A containing 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene releases rigid additive molecules, which exist in the PETG matrix in a physically dispersed or micro-grafted form. The fluorene ring planar structure of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene acts as a physical crosslinking point at the molecular level, hindering the segmental movement of the PETG molecular chains, which is the reason for the increased macroscopic glass transition temperature of the material. At the same time, masterbatch B containing ureidopyrimidinone functionalized diols releases functionalized diols, and the ureidopyrimidinone groups dispersed in the matrix exhibit self-assembly behavior. The two ureidopyrimidinone groups form a thermally reversible dimer through hydrogen bonds, constructing a three-dimensional physical crosslinking network, endowing the material with elasticity and toughness, thereby obtaining a composite material with both high heat resistance and high toughness.

[0022] As a preferred embodiment of the present invention, in S1, the mass ratio of 9,9-bis(4-hydroxyphenyl)fluorene, potassium carbonate, anhydrous DMSO and ethylene carbonate is 100:(26-28):800:(110-120), for example, it can be 100:(26, 26.2, 26.4, 26.6, 26.8, 27.0, 27.2, 27.4, 27.6, 27.8 or 28):800:(110, 111, 112, 113, 114, 115, 116, 117, 118, 119 or 120), but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0023] In some alternative embodiments, the first temperature is 0-5°C, for example, it can be 0°C, 0.5°C, 1°C, 1.5°C, 2°C, 2.5°C, 3°C, 3.5°C, 4°C, 4.5°C or 5°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0024] In some optional embodiments, the pre-activation time is 0.8-1h, for example, it can be 0.8h, 0.82h, 0.84h, 0.86h, 0.88h, 0.9h, 0.92h, 0.94h, 0.96h, 0.98h or 1.0h, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0025] In some alternative embodiments, the second temperature is 130-135°C, for example, it can be 130°C, 130.5°C, 131°C, 131.5°C, 132°C, 132.5°C, 133°C, 133.5°C, 134°C, 134.5°C or 135°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0026] In some alternative embodiments, the reaction time at the second temperature is 8-9 hours, for example, 8.0 hours, 8.1 hours, 8.2 hours, 8.3 hours, 8.4 hours, 8.5 hours, 8.6 hours, 8.7 hours, 8.8 hours, 8.9 hours, or 9.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0027] In some optional embodiments, the mixed solvent is toluene and ethanol in a volume ratio of 3:1.

[0028] As a preferred embodiment of the present invention, in S2, the mass ratio of 2-amino-4-hydroxy-6-methylpyrimidine, anhydrous THF, 1,1'-carbodiimidazole to Serinol solution is (100-110):600:(115-127):500. For example, it can be (100, 101, 102, 103, 104, 105, 106, 107, 108, 109 or 110):600:(115, 116.2, 117.4, 118.6, 119.8, 121, 122.2, 123.4, 124.6, 125.8 or 127):500, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0029] In some optional embodiments, the stirring activation time is 0.8-1h, for example, it can be 0.8h, 0.82h, 0.84h, 0.86h, 0.88h, 0.9h, 0.92h, 0.94h, 0.96h, 0.98h or 1.0h, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0030] In some alternative embodiments, the third temperature is 30-35°C, for example, it can be 30°C, 30.5°C, 31°C, 31.5°C, 32°C, 32.5°C, 33°C, 33.5°C, 34°C, 34.5°C or 35°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0031] In some optional embodiments, the reaction time at the third temperature is 2-3 hours, for example, 2.0 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours, or 3.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0032] In some optional embodiments, the Serinol solution has a mass fraction of 20 wt.% and the solvent is anhydrous THF.

[0033] In some optional embodiments, the dripping time is 1.5-2 hours, for example, 1.5 hours, 1.55 hours, 1.6 hours, 1.65 hours, 1.7 hours, 1.75 hours, 1.8 hours, 1.85 hours, 1.9 hours, 1.95 hours, or 2.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0034] In some optional embodiments, the room temperature stirring reaction time is 6-7 hours, for example, 6.0 hours, 6.1 hours, 6.2 hours, 6.3 hours, 6.4 hours, 6.5 hours, 6.6 hours, 6.7 hours, 6.8 hours, 6.9 hours, or 7.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0035] As a preferred embodiment of the present invention, in S3, the mass ratio of the bottle-grade PETG resin to 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene is 850:(150-160), for example, it can be 850:(150, 151, 152, 153, 154, 155, 156, 157, 158, 159 or 160), but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0036] In some optional embodiments, the bottle-grade PETG resin has an incoming moisture content of ≤0.01wt%, a Tg of ≥75℃, a total transmittance of ≥90% for 2mm sheets, and a haze of ≤1.5%.

[0037] In some optional embodiments, the temperature zones of the twin-screw extruder are set as follows: Zone 1 235°C, Zone 2 238°C, Zone 3 240°C, and Die Head 242°C.

[0038] As a preferred technical solution of the present invention, in S4, the mass ratio of the bottle-grade PETG resin to the ureidopyrimidinone functionalized diol is 850:(150-160), for example, it can be 850:(150, 151, 152, 153, 154, 155, 156, 157, 158, 159 or 160), but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0039] In some optional embodiments, the temperature zones of the twin-screw extruder are set as follows: Zone 1 230°C, Zone 2 232°C, Zone 3 234°C, and Die Head 236°C.

[0040] As a preferred technical solution of the present invention, in S5, the mass ratio of bottle-grade PETG resin, masterbatch A and masterbatch B is 9000:(666-670):(333-340), for example, it can be 9000:(666, 666.4, 666.8, 667.2, 667.6, 668, 668.4, 668.8, 669.2, 669.6 or 670):(333, 333.7, 334.4, 335.1, 335.8, 336.5, 337.2, 337.9, 338.6, 339.3 or 340), but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0041] In some optional embodiments, the temperature zones of the twin-screw extruder are set as follows: Zone 1 235°C, Zone 2 238°C, Zone 3 242°C, Zone 4 245°C, and the die head 245°C.

[0042] Secondly, the present invention provides a bottle-grade modified PETG chip prepared using the preparation method described in the first aspect.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows: By introducing 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, the present invention effectively constructs a highly stable molecular framework, improving the glass transition temperature and heat distortion temperature of PETG material, enabling it to meet the application scenarios with higher requirements for heat resistance, such as hot filling and steam sterilization; Secondly, the present invention introduces a ureidopyrimidinone functionalized diol with a dynamic reversible hydrogen bond network. This dynamic network forms physical cross-links at the operating temperature. When the material is subjected to external impact, it can effectively dissipate energy through the reversible breaking and recombination of hydrogen bonds, thereby greatly enhancing the toughness of the material. Since the introduced functional additives have good compatibility with the PETG matrix, the modified PETG chips obtained can maintain optical transparency, meeting the requirements of bottle-grade materials for high clarity. Detailed Implementation

[0044] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The embodiments described herein are specific implementations of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limiting the implementation of the present invention or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein.

[0045] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone any further purification treatment.

[0046] Example 1

[0047] This embodiment provides a bottle-grade modified PETG chip and its preparation method, the preparation method specifically including the following steps:

[0048] S1, 100g of 9,9-bis(4-hydroxyphenyl)fluorene, 28g of potassium carbonate and 800g of anhydrous DMSO were mixed, and the mixture was pre-activated at 0℃ for 0.9h under a nitrogen atmosphere. Then 110g of ethylene carbonate was added and the temperature was adjusted to 135℃ for 8h. After the reaction was completed, the reaction solution was poured into ice water to precipitate, filtered and washed with deionized water to 6.8, filtered to remove water by pressure filtration, and then dissolved by heating under reflux in a mixed solvent. After hot filtration, the solution was cooled to crystallize and dried. The mixed solvent was toluene and ethanol in a volume ratio of 3:1 to obtain 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene.

[0049] S2, 105g of 2-amino-4-hydroxy-6-methylpyrimidine was dispersed in 600g of anhydrous THF. Under a nitrogen atmosphere, the temperature was adjusted to 3℃ and 127g of 1,1'-carbonyldiimidazole was added and stirred for 0.8h to activate the reaction. The temperature was then adjusted to 35℃ and the reaction was carried out for 2.5h to obtain an intermediate solution. The intermediate solution was added dropwise to 500g of Serinol solution at 0℃ for 2h. The mass fraction of Serinol solution was 20wt.% and the solvent was anhydrous THF. After the addition was completed, the reaction was stirred at room temperature for 6h. After the reaction was completed, the reaction solution was slowly poured into anhydrous n-hexane to precipitate. The solid was collected by suction filtration, redissolved in ethyl acetate and poured into n-hexane to precipitate again. The mixture was filtered and dried to obtain a ureidylpyrimidinone functionalized diol.

[0050] S3. 850g of bottle-grade PETG resin and 160g of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene are dry-mixed and fed into a co-rotating twin-screw extruder. The bottle-grade PETG resin has an inlet moisture content ≤0.01wt%, Tg ≥75℃, and a total transmittance of 2mm flakes ≥90% and a haze ≤1.5%. The temperature zones of the twin-screw extruder are set as follows: Zone 1 235℃, Zone 2 238℃, Zone 3 240℃, and die head 242℃. The extrusion process involves water cooling, dewatering with an air knife, and pelletizing to obtain masterbatch A.

[0051] S4. 850g of bottle-grade PETG resin and 150g of ureidopyrimidinone functionalized diol are dry-mixed and fed into a co-rotating twin-screw extruder. The temperature zones of the twin-screw extruder are set as follows: Zone 1 230℃, Zone 2 232℃, Zone 3 234℃, and Die head 236℃. The extrusion process involves water-cooled strands, air knife dewatering, and pelletizing to obtain masterbatch B.

[0052] S5, 9000g of bottle-grade PETG resin, 668g of masterbatch A and 340g of masterbatch B are dry-mixed and fed into a co-rotating twin-screw extruder for melt blending and granulation. The temperature zones of the twin-screw extruder are set as follows: Zone 1 235℃, Zone 2 238℃, Zone 3 242℃, Zone 4 245℃, and die head 245℃. After extrusion, water-cooled strips are formed, water is removed by air knife, and pellets are cut to obtain bottle-grade modified PETG chips.

[0053] Example 2

[0054] This embodiment provides a bottle-grade modified PETG chip and its preparation method, the preparation method specifically including the following steps:

[0055] S1, 100g of 9,9-bis(4-hydroxyphenyl)fluorene, 26g of potassium carbonate and 800g of anhydrous DMSO were mixed, and the mixture was pre-activated at 5°C for 1h under a nitrogen atmosphere. Then 120g of ethylene carbonate was added and the temperature was adjusted to 132°C for 8.5h. After the reaction was completed, the reaction solution was poured into ice water to precipitate, filtered and washed with deionized water until 7, filtered to remove water by pressure filtration, and then dissolved by heating under reflux in a mixed solvent. After hot filtration, the mixture was cooled to crystallize and dried. The mixed solvent was toluene and ethanol in a volume ratio of 3:1 to obtain 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene.

[0056] S2, 100g of 2-amino-4-hydroxy-6-methylpyrimidine was dispersed in 600g of anhydrous THF under a nitrogen atmosphere. The temperature was adjusted to 5℃ and 120g of 1,1'-carbonyldiimidazole was added and stirred for 1h. The temperature was then adjusted to 30℃ and reacted for 3h to obtain an intermediate solution. The intermediate solution was added dropwise to 500g of Serinol solution at 2℃ for 1.5h. The mass fraction of Serinol solution was 20wt.% and the solvent was anhydrous THF. After the addition was complete, the reaction was stirred at room temperature for 7h. After the reaction was completed, the reaction solution was slowly poured into anhydrous n-hexane to precipitate. The solid was collected by suction filtration, redissolved in ethyl acetate and poured into n-hexane to precipitate again. The mixture was filtered and dried to obtain a ureidylpyrimidinone functionalized diol.

[0057] S3, 850g of bottle-grade PETG resin and 155g of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene are dry-mixed and fed into a co-rotating twin-screw extruder. The bottle-grade PETG resin has an input moisture content ≤0.01wt%, Tg ≥75℃, and a total transmittance of 2mm flakes ≥90% and a haze ≤1.5%. The temperature zones of the twin-screw extruder are set as follows: Zone 1 235℃, Zone 2 238℃, Zone 3 240℃, and die head 242℃. The extrusion process involves water-cooled strands, air knife dewatering, and pelletizing to obtain masterbatch A.

[0058] S4. 850g of bottle-grade PETG resin and 160g of ureidopyrimidinone functionalized diol are dry-mixed and fed into a co-rotating twin-screw extruder. The temperature zones of the twin-screw extruder are set as follows: Zone 1 230℃, Zone 2 232℃, Zone 3 234℃, and Die head 236℃. The extruder is then water-cooled, dehydrated by an air knife, and pelletized to obtain masterbatch B.

[0059] S5, 9000g of bottle-grade PETG resin, 670g of masterbatch A and 333g of masterbatch B are dry-mixed and fed into a co-rotating twin-screw extruder for melt blending and granulation. The temperature zones of the twin-screw extruder are set as follows: Zone 1 235℃, Zone 2 238℃, Zone 3 242℃, Zone 4 245℃, and the die head 245℃. After extrusion, water-cooled strips are formed, water is removed by air knife, and the strips are granulated to obtain bottle-grade modified PETG chips.

[0060] Example 3

[0061] This embodiment provides a bottle-grade modified PETG chip and its preparation method, the preparation method specifically including the following steps:

[0062] S1, 100g of 9,9-bis(4-hydroxyphenyl)fluorene, 27g of potassium carbonate and 800g of anhydrous DMSO were mixed, and the mixture was pre-activated at 2℃ for 0.8h under a nitrogen atmosphere. Then 115g of ethylene carbonate was added and the temperature was adjusted to 130℃ for 9h. After the reaction was completed, the reaction solution was poured into ice water to precipitate, filtered and washed with deionized water to 6.9, filtered to remove water by pressure filtration, and then dissolved by heating under reflux in a mixed solvent. After hot filtration, the solution was cooled to crystallize and dried. The mixed solvent was toluene and ethanol in a volume ratio of 3:1 to obtain 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene.

[0063] S2, 110g of 2-amino-4-hydroxy-6-methylpyrimidine was dispersed in 600g of anhydrous THF. Under a nitrogen atmosphere, the temperature was adjusted to 0℃ and 115g of 1,1'-carbonyldiimidazole was added and stirred for 0.9h. The temperature was then adjusted to 32℃ and reacted for 2h to obtain an intermediate solution. The intermediate solution was added dropwise to 500g of Serinol solution at 5℃ for 1.8h. The mass fraction of Serinol solution was 20wt.% and the solvent was anhydrous THF. After the addition was complete, the reaction was stirred at room temperature for 6.5h. After the reaction was completed, the reaction solution was slowly poured into anhydrous n-hexane to precipitate. The solid was collected by suction filtration, redissolved in ethyl acetate and poured into n-hexane to precipitate again. The mixture was filtered and dried to obtain a ureidylpyrimidinone functionalized diol.

[0064] S3, 850g of bottle-grade PETG resin and 150g of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene are dry-mixed and fed into a co-rotating twin-screw extruder. The bottle-grade PETG resin has an inlet moisture content ≤0.01wt%, Tg ≥75℃, and a total transmittance of 2mm flakes ≥90% and a haze ≤1.5%. The temperature zones of the twin-screw extruder are set as follows: Zone 1 235℃, Zone 2 238℃, Zone 3 240℃, and die head 242℃. The extrusion process involves water cooling, dewatering with an air knife, and pelletizing to obtain masterbatch A.

[0065] S4. 850g of bottle-grade PETG resin and 158g of ureidopyrimidinone functionalized diol are dry-mixed and fed into a co-rotating twin-screw extruder. The temperature zones of the twin-screw extruder are set as follows: Zone 1 230℃, Zone 2 232℃, Zone 3 234℃, and Die head 236℃. The extruder is then water-cooled, dehydrated by an air knife, and pelletized to obtain masterbatch B.

[0066] S5, 9000g of bottle-grade PETG resin, 666g of masterbatch A and 335g of masterbatch B are dry-mixed and fed into a co-rotating twin-screw extruder for melt blending and granulation. The temperature zones of the twin-screw extruder are set as follows: Zone 1 235℃, Zone 2 238℃, Zone 3 242℃, Zone 4 245℃, and the die head 245℃. After extrusion, water-cooled strips are formed, and water is removed by air knife before pelletizing to obtain a bottle-grade modified PETG chip.

[0067] Example 4

[0068] This embodiment provides a bottle-grade modified PETG chip and its preparation method, the preparation method specifically including the following steps:

[0069] S1, 100g of 9,9-bis(4-hydroxyphenyl)fluorene, 27.5g of potassium carbonate and 800g of anhydrous DMSO were mixed under a nitrogen atmosphere and the temperature was adjusted to 4℃ for pre-activation for 0.85h. Then 118g of ethylene carbonate was added and the temperature was adjusted to 134℃ for reaction for 8.2h. After the reaction was completed, the reaction solution was poured into ice water to precipitate, filtered and washed with deionized water to 6.8, filtered to remove water by pressure filtration, and then dissolved by heating under reflux in a mixed solvent. After hot filtration, the solution was cooled to crystallize and dried. The mixed solvent was toluene and ethanol in a volume ratio of 3:1 to obtain 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene.

[0070] S2, 102g of 2-amino-4-hydroxy-6-methylpyrimidine was dispersed in 600g of anhydrous THF under a nitrogen atmosphere. The temperature was adjusted to 2℃ and 125g of 1,1'-carbonyldiimidazole was added and stirred for 0.85h. The temperature was then adjusted to 34℃ and reacted for 2.8h to obtain an intermediate solution. Under the first temperature condition of 3℃, the intermediate solution was added dropwise to 500g of Serinol solution. The dropwise addition time was 1.6h. The mass fraction of Serinol solution was 20wt.% and the solvent was anhydrous THF. After the dropwise addition was completed, the reaction was stirred at room temperature for 6.2h. After the reaction was completed, the reaction solution was slowly poured into anhydrous n-hexane to precipitate. The solid was collected by suction filtration, redissolved in ethyl acetate and poured into n-hexane to precipitate again. After filtration and drying, ureidopyrimidinone functionalized diol was obtained.

[0071] S3, 850g of bottle-grade PETG resin and 152g of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene are dry-mixed and fed into a co-rotating twin-screw extruder. The bottle-grade PETG resin has an inlet moisture content ≤0.01wt%, Tg ≥75℃, and a total transmittance of 2mm flakes ≥90% and a haze ≤1.5%. The temperature zones of the twin-screw extruder are set as follows: Zone 1 235℃, Zone 2 238℃, Zone 3 240℃, and die head 242℃. The extrusion process involves water-cooled strands, air knife dewatering, and pelletizing to obtain masterbatch A.

[0072] S4. 850g of bottle-grade PETG resin and 154g of ureidopyrimidinone functionalized diol are dry-mixed and fed into a co-rotating twin-screw extruder. The temperature zones of the twin-screw extruder are set as follows: Zone 1 230℃, Zone 2 232℃, Zone 3 234℃, and Die head 236℃. The extruder is then water-cooled, dehydrated by an air knife, and pelletized to obtain masterbatch B.

[0073] S5, 9000g of bottle-grade PETG resin, 667g of masterbatch A and 338g of masterbatch B are dry-mixed and fed into a co-rotating twin-screw extruder for melt blending and granulation. The temperature zones of the twin-screw extruder are set as follows: Zone 1 235℃, Zone 2 238℃, Zone 3 242℃, Zone 4 245℃, and die head 245℃. After extrusion, water-cooled strips are formed, water is removed by air knife, and pellets are cut to obtain bottle-grade modified PETG chips.

[0074] Comparative Example 1

[0075] This comparative example provides a bottle-grade modified PETG chip and its preparation method. The difference between this example and Example 1 is that in S5, masterbatch A is replaced with an equal mass of bottle-grade PETG resin, while other process parameters and operating conditions are exactly the same as in Example 1.

[0076] Comparative Example 2

[0077] This comparative example provides a bottle-grade modified PETG chip and its preparation method. The difference between this example and Example 1 is that in S5, masterbatch B is replaced with an equal mass of bottle-grade PETG resin, while other process parameters and operating conditions are exactly the same as in Example 1.

[0078] Comparative Example 3

[0079] This comparative example provides a bottle-grade modified PETG chip and its preparation method. The difference between this example and Example 1 is that in S5, masterbatch A and masterbatch B are replaced with equal masses of bottle-grade PETG resin, while other process parameters and operating conditions are exactly the same as in Example 1.

[0080] The bottle-grade modified PETG chips prepared in Examples 1-4 and Comparative Examples 1-3 were subjected to performance testing, and the test methods are as follows:

[0081] The test method for glass transition temperature is GB / T19466.2;

[0082] The toughness test method is GB / T1843;

[0083] The transparency test method is GB / T2410.

[0084] The test results are shown in Table 1.

[0085] Table 1. Test results of bottle-grade modified PETG slices prepared in Examples 1-4 and Comparative Examples 1-3

[0086]

[0087] As shown in the table, compared to Example 1, Comparative Example 1 showed a decrease in glass transition temperature, unchanged impact strength, and decreased transparency; Comparative Example 2 showed unchanged glass transition temperature, decreased impact strength, and decreased transparency; and Comparative Example 3 showed a decrease in glass transition temperature, decreased impact strength, and decreased transparency. This is because Comparative Example 1 lacked masterbatch A, thus failing to introduce rigid 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, resulting in a decrease in glass transition temperature. Furthermore, due to good compatibility, the transparency did not decrease significantly. Comparative Example 2 lacked masterbatch B, resulting in a lack of a physical cross-linking network, thus decreasing toughness. Comparative Example 3 lacked both masterbatch A and masterbatch B, lacking both rigid 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene and the toughening effect of ureidopyrimidinone functionalized diols, resulting in a decrease in both glass transition temperature and impact strength.

[0088] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A process for the preparation of a bottle grade modified PETG chip, characterized in that, The preparation method includes: S1, 9,9-bis(4-hydroxyphenyl)fluorene, potassium carbonate and anhydrous DMSO are mixed and pre-activated, and then ethylene carbonate is added to react to obtain 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene; S2, 2-amino-4-hydroxy-6-methylpyrimidine is dispersed in anhydrous THF, and 1,1'-carbonyldiimidazole is added for activation. The reaction yields an intermediate solution, which is then added dropwise to Serinol solution to react and yield a ureidopyrimidinone functionalized diol. S3, bottle-grade PETG resin is dry-mixed with 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene and then fed into a co-rotating twin-screw extruder to obtain masterbatch A; S4, bottle-grade PETG resin is dry-mixed with ureidopyrimidinone functionalized diol and fed into a co-rotating twin-screw extruder to obtain masterbatch B; S5, bottle-grade PETG resin, masterbatch A and masterbatch B are dry-mixed and fed into a co-rotating twin-screw extruder to obtain a bottle-grade modified PETG chip; The mass ratio of 2-amino-4-hydroxy-6-methylpyrimidine, anhydrous THF, 1,1'-carbodiimidazole to Serinol solution is (100-110):600:(115-127):500; The Serinol solution has a mass fraction of 20 wt.% and is in anhydrous THF as the solvent.

2. The method for preparing bottle-grade modified PETG chips according to claim 1, characterized in that, In S1: The mass ratio of 9,9-bis(4-hydroxyphenyl)fluorene, potassium carbonate, anhydrous DMSO and ethylene carbonate is 100:(26-28):800:(110-120).

3. The method for preparing bottle-grade modified PETG chips according to claim 1, characterized in that, In S3: The bottle-grade PETG resin has an incoming moisture content of ≤0.01wt%, a Tg of ≥75℃, a total transmittance of ≥90% for 2mm sheets, and a haze of ≤1.5%. The mass ratio of the bottle-grade PETG resin to 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene is 850:(150-160).

4. The method for preparing bottle-grade modified PETG chips according to claim 1, characterized in that, In S3: The temperature zones of the twin-screw extruder are set as follows: Zone 1 235℃, Zone 2 238℃, Zone 3 240℃, and Die head 242℃.

5. The method for preparing bottle-grade modified PETG chips according to claim 1, characterized in that, In S4: The mass ratio of the bottle-grade PETG resin to the ureidopyrimidinone functionalized diol is 850:(150-160).

6. The method for preparing bottle-grade modified PETG chips according to claim 1, characterized in that, In S4: The temperature zones of the twin-screw extruder are set as follows: Zone 1 230℃, Zone 2 232℃, Zone 3 234℃, and Die head 236℃.

7. The method for preparing bottle-grade modified PETG chips according to claim 1, characterized in that, In S5: The mass ratio of bottle-grade PETG resin, masterbatch A to masterbatch B is 9000:(666-670):(333-340). The temperature zones of the twin-screw extruder are set as follows: Zone 1 235℃, Zone 2 238℃, Zone 3 242℃, Zone 4 245℃, and Die head 245℃.

8. A bottle-grade modified PETG chip obtained by the preparation method according to any one of claims 1-7.

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