Ultrathin PET (Polyethylene Terephthalate) functional master batch and preparation method thereof

Abstract

According to the ultrathin PET functional master batch and the preparation method thereof disclosed by the invention, UV absorbing groups such as isophorone diester and 2, 4-dihydroxybenzoic acid are introduced, so that the absorption capacity of a molecular chain to ultraviolet rays is enhanced, and meanwhile, the aging resistance of a film is improved. Besides, by utilizing the Beta molecular sieve, the zinc metaborate and other auxiliaries, the uniform distribution of the light stabilizer and the ultraviolet light absorber in the molecular structure is improved, and the non-uniform UV absorption performance of the film caused by molecular arrangement change in the stretching process is effectively avoided. Due to the synergistic effect of the components in the formula, the ultraviolet resistance, strength and thermal stability of the film are improved, the performance uniformity of the film is ensured, and an innovative material solution is provided for preparation of the high-performance ultrathin PET film. According to the preparation method disclosed by the invention, the properties, such as mechanical strength, thermal stability and gas barrier property, of the PET material can be remarkably improved, so that the application requirements of ultrathin products in the fields of packaging, electronics, buildings and the like can be met.

Description

Technical Field

[0001] This invention belongs to the field of polymer material preparation technology, specifically relating to an ultra-thin PET functional masterbatch and its preparation method. Background Technology

[0002] With technological advancements and evolving consumer demands, ultra-thin PET films have found widespread application in packaging, electronics, and construction due to their lightweight, high transparency, excellent mechanical strength, and gas barrier properties. For example, in food packaging, ultra-thin PET films can be used to make food bags, reducing material usage and production costs. In electronics, they serve as substrates or protective films for flexible displays. In construction, they are used for heat insulation, sound insulation, and decoration. Furthermore, their lightweight nature makes them advantageous in electronics, packaging, and automotive applications, facilitating transportation and application. Their high transparency allows for applications requiring light transmission (such as optical films and display protective films). Additionally, their good flexibility makes them suitable for applications in bendable or flexible displays and solar cells.

[0003] However, with the continuous expansion of application areas, the shortcomings of ultra-thin PET films in terms of UV protection have gradually become apparent. For example, due to the small thickness of the ultra-thin film, the PET molecular chains themselves have limited ability to absorb ultraviolet rays, making the film prone to aging or damage when exposed to ultraviolet rays and other environmental factors. This not only affects the service life of the ultra-thin PET film but may also damage the products it packages or protects. In addition, during the manufacturing of ultra-thin films, especially during the stretching process, the stretching of the film may change the molecular arrangement of the film, leading to uneven distribution of ultraviolet absorbers or reduced photostability. The stretching process may also cause uneven properties in the stretching direction of the film, affecting the uniformity of UV protection performance, particularly the distribution of light stabilizers and ultraviolet absorbers within the film.

[0004] Therefore, improving the UV resistance of ultra-thin PET films has become an urgent problem to be solved in the field of polymer material preparation technology. This invention addresses this problem by proposing an ultra-thin functional PET masterbatch with excellent UV resistance and its preparation method. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an ultra-thin PET functional masterbatch and its preparation method, so as to reduce or avoid the problems mentioned above.

[0006] To address the aforementioned technical problems, this invention proposes a functional PET masterbatch for ultra-thin products, used as all or part of the raw materials for preparing ultra-thin products. The ultra-thin PET masterbatch is prepared from the following raw materials in parts by weight: terephthalic acid: 95-105 parts by weight; ethylene glycol: 65-75 parts by weight; isophorone diester: 25-35 parts by weight; 2,4-dihydroxybenzoic acid: 15-25 parts by weight; titanium tetrachloride: 0.05-0.10 parts by weight; antimony acetate: 0.04-0.08 parts by weight; phosphoric acid: 0.03-0.06 parts by weight; 2,6-di-tert-butyl-p-cresol: 0.03-0.08 parts by weight; zinc metaborate: 0.01-0.03 parts by weight; diethylene glycol: 3-7 parts by weight; xylene: 2-4 parts by weight; and Beta molecular sieve: 8-12 parts by weight.

[0007] This invention also proposes a method for preparing the above-mentioned functional masterbatch, comprising the following steps: In an esterification tank, terephthalic acid, ethylene glycol, 2,4-dihydroxybenzoic acid, diethylene glycol, and xylene are weighed and added sequentially. The added materials are stirred evenly, and then the temperature is raised to 150°C. Titanium tetrachloride is then added as a catalyst. Nitrogen gas is introduced under normal pressure to purge air from the esterification tank, gradually reducing the pressure to 0.5 MPa. The esterification reaction is carried out under nitrogen protection for 6-8 hours, with the reaction temperature controlled at 190-220°C. With 30 minutes remaining in the esterification reaction time, Beta molecular sieves are added to the esterification tank. After the esterification reaction is completed, the temperature inside the esterification tank is lowered to 220°C. Phosphoric acid is added according to the formula ratio while maintaining nitrogen protection. The mixture is stirred for 5-10 minutes to ensure the phosphoric acid is homogeneous. Uniform distribution; gradually raise the temperature in the esterification tank to 250℃-270℃, adjust the pressure in the tank to 500-1000Pa, add antimony acetate as a polycondensation catalyst according to the formula ratio, and add isophorone diester; maintain under nitrogen protection and pressure of 500-1000Pa, and continue the pre-polymerization reaction in the esterification tank for 3-5 hours; after the pre-polymerization reaction time is over, transfer the pre-polymerization product from the esterification tank to the polycondensation tank, and add 2,6-di-tert-butyl-p-cresol and zinc metaborate; reduce the pressure in the polycondensation tank to 10-50Pa; then gradually raise the temperature to 280℃-290℃ and carry out the polycondensation reaction for 2-3 hours. When the polymer molecular weight reaches 35,000-45,000 g / mol, the polycondensation reaction is considered complete.

[0008] Preferably, the method further includes: introducing polyester melt from a polycondensation tank into a twin-screw extruder, extruding and cooling it to form strips; and then pelletizing it after cooling.

[0009] This invention enhances the absorption capacity of the molecular chain for ultraviolet light by introducing UV-absorbing groups such as isophorone diester and 2,4-dihydroxybenzoic acid, while simultaneously improving the film's aging resistance. Furthermore, the use of Beta molecular sieves, zinc metaborate, and other additives improves the uniform distribution of light stabilizers and UV absorbers in the molecular structure, effectively preventing uneven UV absorption performance caused by changes in molecular arrangement during film stretching. The synergistic effect of the components in the formulation not only improves the film's UV resistance, strength, and thermal stability but also ensures the uniformity of film performance, providing an innovative material solution for the preparation of high-performance ultrathin PET films. The preparation method of this invention can significantly improve the properties of PET materials, such as mechanical strength, thermal stability, and gas barrier properties, thereby meeting the application requirements of ultrathin products in packaging, electronics, construction, and other fields. Detailed Implementation

[0010] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, the specific embodiments of the present invention will now be described in detail.

[0011] To address the issues with the UV resistance of ultra-thin PET films, this invention functionally modifies polyethylene terephthalate (PET) to prepare a specialized functional masterbatch suitable for ultra-thin products. Through this invention and its preparation method, the UV resistance of PET materials can be significantly improved, while also enhancing the material's mechanical strength, thermal stability, and gas barrier properties, thereby meeting the application requirements of ultra-thin products in packaging, electronics, construction, and other fields.

[0012] Specifically, this invention proposes a functional PET masterbatch for ultra-thin products, which can be used as a raw material for preparing ultra-thin PET products, for example, as all the raw materials for preparing ultra-thin PET products, or as part of the raw materials for preparing ultra-thin PET products, and can be combined with other raw materials to prepare the desired ultra-thin PET products.

[0013] In one specific embodiment, the ultra-thin PET functional masterbatch of the present invention is prepared from the following raw materials in parts by weight: terephthalic acid (PTA): 95-105 parts by weight; ethylene glycol (EG): 65-75 parts by weight; isophorone diester (IPDE): 25-35 parts by weight; 2,4-dihydroxybenzoic acid (2,4-DHBA): 15-25 parts by weight; titanium tetrachloride (TiCl4): 0.05-0.10 parts by weight. Parts by weight; Antimony acetate (Sb2O3): 0.04-0.08 parts by weight; Phosphoric acid (H3PO4): 0.03-0.06 parts by weight; 2,6-Di-tert-butyl-p-cresol (BHT): 0.03-0.08 parts by weight; Zinc metaborate: 0.01-0.03 parts by weight; Diethylene glycol (DEG): 3-7 parts by weight; Xylene: 2-4 parts by weight; Beta molecular sieve: 8-12 parts by weight.

[0014] In this process, PTA, as the main dicarboxylic acid component of the polyester, provides a stable structure for the main chain. EG provides the diols required for the reaction, regulating the flexibility and viscosity of the polyester molecules. IPDE improves mechanical properties and thermal stability by introducing rigid groups, while also assisting in enhancing UV resistance. 2,4-DHBA, as a UV-absorbing component, participates in the copolymerization of the polyester chain through its hydroxyl and carboxyl groups. TiCl4 acts as a catalyst in the esterification stage, promoting rapid esterification. Sb2O3 acts as a catalyst in the polymerization stage, used to increase the polymerization rate and molecular weight. H3PO4 stabilizes the polyester chain structure and suppresses side reactions. BHT inhibits oxidative degradation of the material at high temperatures. Zinc metaborate improves the thermal stability of the film during high-temperature stretching. DEG acts as an auxiliary solvent, helping to regulate the viscosity of the reaction and preventing premature polymer precipitation. Xylene improves miscibility in the early stages of the reaction and helps evaporate byproduct water. Beta molecular sieves are a type of nanoscale molecular sieve with a 12-membered ring cross-channel structure, used to ensure efficient dehydration in esterification reactions. At the same time, their unique cageless three-dimensional channel structure is conducive to the diffusion of reactant and product molecules, and also has shape-selective catalysis effect.

[0015] The raw materials of this invention involve a complex chemical reaction process, mainly including the reaction of the ester groups of IPDE with the carboxyl groups of PTA to generate polyester chains. Secondly, the carboxyl groups of DHBA react with the hydroxyl groups of EG to undergo an esterification reaction, generating esterified monomers, providing precursors for subsequent polymerization reactions. Thirdly, the ester groups of IPDE react with the carboxyl groups of DHBA to form a copolymer. Finally, all the above intermediates are mixed and polymerized together with EG to form PET polymer chains.

[0016] IPDE, possessing two ester groups, can undergo esterification reactions with PTA and EG. Furthermore, the ester groups of IPDE can react with the carboxyl groups in PTA and the hydroxyl groups in EG to form long-chain polyesters. The introduction of IPDE contributes to the rigidity of the molecular chain and a certain degree of UV absorption. DHBA, being an aromatic compound containing phenolic hydroxyl groups, allows its carboxyl groups to esterify with EG and PTA, while its phenolic hydroxyl groups can copolymerize with IPDE through esterification. Simultaneously, the presence of phenolic hydroxyl groups provides functional groups for UV absorption.

[0017] Furthermore, the ultra-thin PET functional masterbatch of the present invention can be prepared by the following method.

[0018] Specifically, the method includes the following steps: First, in a stainless steel esterification tank, terephthalic acid, ethylene glycol, 2,4-dihydroxybenzoic acid, diethylene glycol, and xylene are weighed and added sequentially. The materials are stirred evenly using a mechanical stirring device in the stainless steel esterification tank, and then the temperature is raised to 150°C. Then, titanium tetrachloride is added as a catalyst, and nitrogen gas is introduced under normal pressure to purge the air from the esterification tank, gradually reducing the pressure to 0.5 MPa. The esterification reaction is carried out under nitrogen protection for 6-8 hours, and the reaction temperature is controlled at 190-220°C. During the esterification reaction, the by-product water generated by the esterification reaction is evaporated and condensed and discharged through a condenser connected to the top of the stainless steel esterification tank.

[0019] With 30 minutes remaining in the esterification reaction, add Beta molecular sieves to the stainless steel esterification tank. Simultaneously, detect a significant decrease or even cessation of water output from the condenser to indicate the esterification reaction is complete. Lower the temperature inside the esterification tank to 220℃. Maintain under nitrogen protection and add phosphoric acid according to the formula ratio. Stir for 5-10 minutes using the mechanical stirring device in the stainless steel esterification tank to ensure uniform distribution of phosphoric acid.

[0020] The temperature inside the esterification tank is gradually increased to 250℃-270℃, and the pressure inside the tank is adjusted to 500-1000Pa. With the stirring of the mechanical stirring device, antimony acetate is added as a polycondensation catalyst according to the formula ratio, and isophorone diester is added. Under nitrogen protection and pressure of 500-1000Pa, the pre-polycondensation reaction is continued in the esterification tank for 3-5 hours.

[0021] After the pre-polymerization reaction is completed, the pre-polymerization product is transferred from the stainless steel esterification tank to the stainless steel polycondensation tank, and 2,6-di-tert-butyl-p-cresol and zinc metaborate are added. The pressure inside the stainless steel polycondensation tank is reduced to 10-50 Pa through a connected vacuum system. Then, the temperature is gradually increased to 280℃-290℃, and the polycondensation reaction is carried out for 2-3 hours. When the polymer molecular weight reaches 35,000-45,000 g / mol, the polycondensation reaction is considered complete.

[0022] The polyester melt is fed from the polycondensation tank into a twin-screw extruder, where it is extruded and cooled to form a long strip. The strip is then rapidly cooled by a water cooling system and granulated into pellets with a diameter of 2-4 mm using a pelletizer.

[0023] The performance of the ultrathin PET film prepared from the ultrathin PET functional masterbatch of the present invention will be described in detail below through specific embodiments 1-6.

[0024] For ease of explanation, the raw materials of the ultra-thin PET functional masterbatch are represented in alphabetical order.

[0025] A: Terephthalic acid (PTA); B: Ethylene glycol (EG); C: Isophorone diester (IPDE); D: 2,4-Dihydroxybenzoic acid (2,4-DHBA); E: Titanium tetrachloride (TiCl4); F: Antimony acetate (Sb2O3); G: Phosphoric acid (H3PO4); H: 2,6-Di-tert-butyl-p-cresol (BHT); I: Zinc metaborate; J: Diethylene glycol (DEG); K: Xylene; L: Beta molecular sieve.

[0026] The following table lists the weight parts of each component of the ultra-thin PET functional masterbatch in Examples 1-6.

[0027]

[0028] The table below shows the performance parameters of ultrathin PET films prepared using the ultrathin PET functional masterbatches of Examples 1-6.

[0029]

[0030] The performance parameters are analyzed as follows: (1) UV resistance. 2,4-Dihydroxybenzoic acid (2,4-DHBA) and isophorone diester (IPDE) provide efficient UV absorption, with absorption peaks covering the UV-A and UV-B ranges. Beta molecular sieves adsorb some UV radiation through pore distribution, further reducing UV transmittance. (2) Strength performance. The optimization of the PTA and EG ratio provides a balance between rigidity and flexibility of the main chain. The rigid structure of isophorone diester (IPDE) significantly improves tensile strength. In the 3μm-8μm range, the strength performance is superior. (3) Thermal stability. The synergistic effect of phosphoric acid and BHT inhibits high-temperature degradation and improves the thermal stability of the film. The isophorone group further enhances the mechanical properties at high temperatures. (4) Gas barrier properties. The synergistic effect of Beta molecular sieves and zinc metaborate filler reduces the gas transmittance of the film.

[0031] In summary, Examples 1-6 demonstrated the potential to optimize UV ​​resistance by fine-tuning the raw material ratios and varying the film thickness, while maintaining a balance between strength, thermal stability, and gas barrier properties.

[0032] To conduct performance comparisons, this invention designed comparative examples 1-6. The design concept of the comparative examples is as follows: omit certain key components (such as IPDE, 2,4-DHBA, Beta molecular sieve, etc.) and test UV absorption or gas barrier parameters; or replace certain components (such as replacing IPDE with a traditional plasticizer or BHT with a conventional antioxidant) and test mechanical properties or thermal stability parameters; or retain the basic components (PTA and EG) to ensure copolymerization and test the performance degradation due to the absence of functional components.

[0033] The adopted measures are shown in the table below.

[0034] raw material Parts by weight in Examples 1-6 The method of handling proportions A 95-105 remain unchanged B 65-75 remain unchanged C 25-35 Omit or replace with phthalate (DOP, 30 parts) D 15-25 Omit or replace with phenol (15 parts) E 0.05-0.10 remain unchanged F 0.04-0.08 Omit G 0.03-0.06 Omit H 0.03-0.08 Omit or replace with common antioxidants (such as vitamin E). I 0.01-0.03 Omit J 3-7 remain unchanged K 2-4 remain unchanged L 8-12 Omit

[0035] The table below shows the performance parameters of the ultrathin PET films in Comparative Examples 1-6, and the reasons for the performance degradation are listed in the corresponding treatment methods of the comparative examples.

[0036]

[0037] In the table above, the comparative examples are processed as follows: Comparative Example 1 omits IPDE and 2,4-DHBA compared to Example 1; Comparative Example 2 replaces IPDE with phthalate compared to Example 2; Comparative Example 3 omits Beta molecular sieve and Sb2O3 compared to Example 3; Comparative Example 4 replaces BHT with vitamin E compared to Example 4; Comparative Example 5 omits zinc metaborate compared to Example 5; and Comparative Example 6 omits H3PO4 compared to Example 6. Apart from the above differences, the remaining components and weight parts of each comparative example and its corresponding example remain unchanged.

[0038] A performance comparison between Comparative Examples 1-6 and Examples 1-6 reveals that the UV transmittance of the films in the comparative examples is significantly increased (≥8% vs. ≤5% in the examples), primarily due to the absence or substitution of IPDE and 2,4-DHBA, and the omission of Beta molecular sieve. In the examples, IPDE provides excellent UV absorption, 2,4-DHBA enhances UV resistance, and Beta molecular sieve further improves overall barrier properties. Furthermore, the strength of the comparative examples is reduced, especially when IPDE is omitted or a flexible plasticizer is used as a substitute; insufficient molecular chain rigidity leads to decreased mechanical properties. Moreover, the thermal stability of the comparative examples is lower than that of the examples, mainly due to the omission of phosphoric acid (H3PO4) and antioxidant (BHT) or the use of substitutes. H3PO4 and BHT synergistically stabilize the molecular chains at high temperatures in the examples. Additionally, the gas barrier properties of the comparative examples are significantly reduced due to the omission of Beta molecular sieve and zinc metaborate. These two components significantly enhance barrier properties in the examples through physical filling and interfacial adsorption.

[0039] By comparing the comparative examples and the embodiments above, the following conclusions can be drawn: the functional components in the embodiments (such as IPDE, 2,4-DHBA, Beta molecular sieves, etc.) significantly contribute to UV resistance, strength, thermal stability, and gas barrier properties. The performance parameters of the comparative example films showed a significant decrease after key components were omitted or replaced, demonstrating the necessity and superiority of the optimized formulation and unique design of the embodiment combinations.

[0040] In summary, the ultrathin PET functional masterbatch of this invention significantly overcomes the shortcomings of ultrathin PET films in terms of thinness and limited UV absorption capacity by optimizing the molecular structure and functional component combination. By introducing UV-absorbing groups such as isophorone diester (IPDE) and 2,4-dihydroxybenzoic acid (2,4-DHBA), the absorption capacity of the molecular chain for UV radiation is enhanced, while simultaneously improving the film's aging resistance. Furthermore, the use of Beta molecular sieves, zinc metaborate, and other additives improves the uniform distribution of light stabilizers and UV absorbers in the molecular structure, effectively avoiding uneven UV absorption performance caused by changes in molecular arrangement during film stretching. The synergistic effect of the components in the formulation not only improves the film's UV resistance, strength, and thermal stability but also ensures the uniformity of film performance, providing an innovative material solution for the preparation of high-performance ultrathin PET films.

[0041] Those skilled in the art should understand that although the present invention has been described with reference to multiple embodiments, not every embodiment contains only one independent technical solution. This description is provided merely for clarity; those skilled in the art should understand the specification as a whole and consider the technical solutions involved in each embodiment as being able to be combined with each other to form different embodiments to understand the scope of protection of the present invention.

[0042] The above description is merely an illustrative embodiment of the present invention and is not intended to limit the scope of the invention. Any equivalent changes, modifications, and combinations made by those skilled in the art without departing from the concept and principles of the present invention should fall within the scope of protection of the present invention.

Claims

1. A functional PET masterbatch for ultra-thin applications, used as a sole or partial raw material in the preparation of ultra-thin products, characterized in that, The ultra-thin PET functional masterbatch is prepared from the following raw materials in parts by weight: terephthalic acid: 95-105 parts by weight; ethylene glycol: 65-75 parts by weight; isophorone diester: 25-35 parts by weight; 2,4-dihydroxybenzoic acid: 15-25 parts by weight; titanium tetrachloride: 0.05-0.10 parts by weight; antimony acetate: 0.04-0.08 parts by weight; phosphoric acid: 0.03-0.06 parts by weight; 2,6-di-tert-butyl-p-cresol: 0.03-0.08 parts by weight; zinc metaborate: 0.01-0.03 parts by weight; diethylene glycol: 3-7 parts by weight; xylene: 2-4 parts by weight; Beta molecular sieve: 8-12 parts by weight.

2. A method for preparing the functional masterbatch as described in claim 1, characterized in that, The method includes the following steps: In an esterification tank, terephthalic acid, ethylene glycol, 2,4-dihydroxybenzoic acid, diethylene glycol, and xylene are weighed and added sequentially. The added materials are stirred evenly, and then the temperature is raised to 150°C. Titanium tetrachloride is then added as a catalyst. Nitrogen gas is introduced under normal pressure to purge air from the esterification tank, gradually reducing the pressure to 0.5 MPa. The esterification reaction is carried out under nitrogen protection for 6-8 hours, with the reaction temperature controlled at 190-220°C. With 30 minutes remaining in the esterification reaction time, Beta molecular sieves are added to the esterification tank. After the esterification reaction is completed, the temperature inside the esterification tank is lowered to 220°C. Phosphoric acid is added according to the formula ratio while maintaining nitrogen protection. The mixture is stirred for 5-10 minutes to ensure uniform distribution of the phosphoric acid. The esterification tank is then... The temperature inside the tank is gradually increased to 250℃-270℃, and the pressure inside the tank is adjusted to 500-1000Pa. Antimony acetate is added as a polycondensation catalyst according to the formula ratio, and isophorone diester is added. Under nitrogen protection and a pressure of 500-1000Pa, the pre-polycondensation reaction continues in the esterification tank for 3-5 hours. After the pre-polycondensation reaction is completed, the pre-polycondensation product is transferred from the esterification tank to the polycondensation tank, and 2,6-di-tert-butyl-p-cresol and zinc metaborate are added. The pressure inside the polycondensation tank is reduced to 10-50Pa. Then, the temperature is gradually increased to 280℃-290℃, and the polycondensation reaction is carried out for 2-3 hours. When the polymer molecular weight reaches 35,000-45,000 g / mol, the polycondensation reaction is considered complete.

3. The method as described in claim 2, characterized in that, The method further includes: introducing polyester melt from a polycondensation tank into a twin-screw extruder, extruding and cooling it to form long strips; and then pelletizing it after cooling.

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