Modified polyester-based cosmetic packaging material and method for preparing the same

Abstract

This invention belongs to the field of polymer materials and discloses a cosmetic packaging material based on modified polyester and its preparation method. The cosmetic packaging material includes the following raw materials in parts by weight: 85-90 parts of PETG resin, 4-6 parts of organo-montmorillonite polyamide graft copolymer, 3-5 parts of modified polyester elastomer, 0.2-0.4 parts of antioxidant, 0.1-0.3 parts of nucleating agent, 0.01-0.1 parts of lubricant, and 0.01-0.1 parts of anti-blocking agent. The organo-montmorillonite polyamide graft copolymer is formed by covalently grafting montmorillonite sheets with polyamide molecular chains. The modified polyester elastomer is a polyester thermoplastic elastomer grafted with benzotriazole ultraviolet absorbing units containing double bonds. This invention uses PETG as the matrix and, by compounding organo-montmorillonite polyamide graft copolymer and modified polyester elastomer as two modifiers, achieves a synergistic improvement in barrier properties, weather resistance, and mechanical properties, while also taking into account processability, safety, and chemical resistance, thus solving the performance shortcomings of traditional PETG cosmetic packaging.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a cosmetic packaging material based on modified polyester and its preparation method. Background Technology

[0002] PETG is a modified copolymer resin of PET, copolymerized from terephthalic acid, ethylene glycol, and 1,4-cyclohexanediethanol (CHDM). Compared to traditional PET, it possesses higher transparency, better toughness and processing fluidity, is non-crystalline, and has extremely low haze, achieving a crystal-like appearance without additional anti-reflective coating. It is widely used in the manufacture of various cosmetic packaging containers such as serum bottles, essential oil bottles, cream boxes, and spray bottles. With the rapid development of the cosmetics industry, high-end and functional products have become the mainstream trends. Cosmetics with highly active ingredients (such as vitamin C, vitamin A, peptides, and essential oils) are becoming increasingly popular. At the same time, consumers' requirements for the barrier properties, UV resistance, weather resistance, and user experience of cosmetic packaging are constantly increasing.

[0003] PETG material itself has many inherent defects, making it difficult to meet the core requirements of high-end cosmetic packaging. These defects are mainly reflected in the following aspects: (1) Insufficient barrier performance: PETG material has limited barrier ability against oxygen and water vapor. Oxygen and water vapor can easily penetrate into the packaging, causing oxidation and hydrolysis of highly active ingredients in cosmetics, resulting in deterioration and failure of cosmetics and shortening the shelf life of products. In particular, for products such as essential oils and antioxidant essences that have extremely high barrier requirements, traditional PETG packaging cannot meet the needs of long-term storage, which seriously limits its application in the field of high-end cosmetics. (2) Poor weather resistance and UV resistance: Cosmetics will inevitably come into contact with ultraviolet rays during production, storage, transportation and use. Traditional PETG material has weak barrier ability against ultraviolet rays in the 280~400nm wavelength band. It will only cause the PETG packaging itself to yellow and become brittle, reduce its mechanical properties, affect the appearance and service life of the packaging, and also penetrate the packaging to irradiate the cosmetics inside, accelerate the decomposition of highly active ingredients, and damage the efficacy and quality of the cosmetics; at the same time, the traditional PETG material has limited resistance to high and low temperatures, and is prone to brittle fracture in low temperature environment and deformation in high temperature environment, making it difficult to adapt to the temperature change requirements of storage and transportation in different regions; (3) It is difficult to balance rigidity and toughness. The traditional PETG material has poor low temperature impact resistance. During e-commerce logistics transportation, the packaging is prone to damage and cracking due to drops and squeezing, resulting in cosmetic leakage. If the rigidity and tensile strength are improved by simply adding inorganic fillers, the toughness will be further reduced, resulting in a contradiction of increased rigidity and decreased toughness, which cannot simultaneously meet the requirements of the packaging for drop resistance, squeezing resistance and molding processing.

[0004] Therefore, developing a modified polyester material that can achieve synergistic improvement in barrier properties, weather resistance, mechanical properties, and safety, while being easy to process, cost-controllable, and industrially feasible, has become an urgent technical problem to be solved in the field of cosmetic packaging materials. Summary of the Invention

[0005] To address the shortcomings mentioned in the background art, the present invention aims to provide a solution that uses PETG as a matrix and combines it with two modifiers, organomontmorillonite-polyamide graft copolymer and modified polyester elastomer, to achieve a synergistic improvement in barrier properties, weather resistance, and mechanical properties, while also taking into account processability, safety, and chemical resistance, thus solving the performance shortcomings of traditional PETG cosmetic packaging.

[0006] The objective of this invention can be achieved through the following technical solutions: A cosmetic packaging material based on modified polyester comprises the following raw materials in parts by weight: 85-90 parts PETG resin, 4-6 parts organomontmorillonite-polyamide graft copolymer, 3-5 parts modified polyester elastomer, 0.2-0.4 parts antioxidant, 0.1-0.3 parts nucleating agent, 0.01-0.1 parts lubricant, and 0.01-0.1 parts antiblocking agent; The organo-montmorillonite-polyamide graft copolymer is made by sodium-modifying montmorillonite and modifying it with organic quaternary ammonium salt to achieve sheet exfoliation, and then polymerizing it in situ with polyamide monomers. At the same time, a bifunctional grafting agent is introduced to form covalent bonds between the montmorillonite sheets and the polyamide molecular chains. Modified polyester elastomers use polyester thermoplastic elastomers as the base material and graft benzotriazole UV absorption units containing double bonds onto the molecular chain through a free radical grafting reaction.

[0007] Preferably, the antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1.

[0008] Preferably, the nucleating agent is a sorbitol-based nucleating agent or an aryl phosphate salt nucleating agent.

[0009] Preferably, the lubricant is one of magnesium stearate, zinc stearate, and calcium stearate.

[0010] Preferably, the anti-blocking agent is nano-silica with a particle size of 10~20nm.

[0011] Preferably, the preparation method of the organomontmorillonite polyamide graft copolymer includes the following steps: (1) Add montmorillonite to deionized water and stir at high speed for 20-40 min to form a uniform montmorillonite suspension. Slowly add saturated sodium chloride solution, heat to 85℃, stir at constant temperature for 3-5 h, filter after reaction, wash with deionized water 3-5 times, dry under vacuum and grind through a 200 mesh sieve to obtain sodium-based montmorillonite. (2) Add sodium montmorillonite to deionized water and stir at high speed for 20-40 min to form a uniform sodium montmorillonite suspension. Heat to 80℃ and slowly add hexadecyltrimethylammonium bromide. Stir at constant temperature for 2-4 h. After the reaction is complete, filter and wash with anhydrous ethanol 3-5 times. After vacuum drying, grind through a 200-mesh sieve to obtain organo-modified montmorillonite. (3) Add organo-modified montmorillonite, m-phenylenediamine, adipic acid, and maleic anhydride-grafted polyethylene glycol to the polymerization reactor, add a small amount of deionized water, heat to 60°C under a nitrogen atmosphere, and stir for 0.5~1.5h; (4) Heat to 180℃, dehydrate under normal pressure for 1.5~2.5h, gradually heat to 240℃, reduce pressure to ≤5kPa, melt polycondense for 2~4h, stop the reaction when the melt becomes stringy, cool down to 100℃ under nitrogen atmosphere, extrude the product into granules, and vacuum dry at 80℃ for 12h to obtain the organic montmorillonite polyamide graft copolymer.

[0012] Preferably, the mass ratio of sodium montmorillonite to hexadecyltrimethylammonium bromide is 4:1; The mass ratio of organo-modified montmorillonite, m-phenylenediamine, oxalic acid, and maleic anhydride-grafted polyethylene glycol is 2:4:3:0.3.

[0013] Preferably, the method for preparing the modified polyester elastomer includes the following steps: A. The polyester thermoplastic elastomer, 2-hydroxy-4-propenoxybenzophenone, and trimethylolpropane triacrylate were dried under vacuum to remove moisture, and benzoyl peroxide was dissolved in anhydrous ethanol. B. The dried polyester thermoplastic elastomer, 2-hydroxy-4-propenoxybenzophenone, trimethylolpropane triacrylate, and antioxidant 1076 are added from the main feed port of the twin-screw extruder, and the benzoyl peroxide ethanol solution is continuously injected from the side feed port. The materials are melted and mixed in the screw and undergo a free radical grafting reaction. Ethanol and reaction byproducts are removed under vacuum. C. The extruded melt is cooled with water, pelletized, and vacuum dried at 80°C for 8-12 hours to obtain the modified polyester elastomer.

[0014] Preferably, the mass ratio of polyester thermoplastic elastomer to 2-hydroxy-4-propenoxybenzophenone is 9:1; The addition amounts of trimethylolpropane triacrylate and benzoyl peroxide are both 1-1.2% of the total mass of PETE polyester elastomer. The amount of antioxidant 1076 added is 0.2~0.4% of the total mass of PETE polyester elastomer; The screw diameter is 30mm, the length-to-diameter ratio is L / D=40, the temperatures of each zone are 160℃, 180℃, 200℃, 210℃ and 200℃ respectively, the screw speed is 200r / min, and the vacuum degree is ≤-0.09MPa.

[0015] A method for preparing a cosmetic packaging material based on modified polyester includes the following steps: S1. Mix all the raw materials of the modified polyester-based cosmetic packaging material evenly according to the formula ratio, and vacuum dry at 120℃ for 6~8h; S2. Extrusion granulation was carried out using a twin-screw extruder with zone temperatures of 250℃, 260℃, 270℃, 265℃, and 260℃, screw speed of 300 r / min, vacuum degree ≤ -0.09 MPa, water-cooled pelletizing, and vacuum drying at 100℃ for 3~5 h to obtain cosmetic packaging materials based on modified polyester.

[0016] The beneficial effects of this invention are: This invention uses PETG as a matrix and combines it with two modifiers: organomontmorillonite-polyamide graft copolymer and modified polyester elastomer. This achieves a synergistic improvement in barrier properties, weather resistance, and mechanical properties, while also considering processability, safety, and chemical resistance, thus addressing the performance shortcomings of traditional PETG cosmetic packaging. The organomontmorillonite-polyamide graft copolymer enhances barrier properties and rigidity; its lamellar labyrinth effect and covalent bonding with PETG are key to the modification. Removing it completely eliminates barrier properties and significantly reduces rigidity. The modified polyester elastomer is the core modifier for enhancing UV resistance, toughening, and aging resistance. Its covalently grafted UV-absorbing units provide permanent UV protection, while the soft-segment polyether glycol provides highly efficient toughening. Removing it reduces UV resistance, toughness, and aging resistance to the level of conventional PETG.

[0017] In this invention, the organo-montmorillonite-polyamide graft copolymer, after graft modification, achieves monodisperse lamellar structures, forming an interwoven lamellar structure within the PETG matrix. Oxygen and water vapor molecules must diffuse around these lamellar structures, significantly increasing the diffusion path and reducing the permeation rate. Simultaneously, polyamide itself is a high-barrier resin; its amide bonds can form hydrogen bonds with gas and water vapor molecules, further adsorbing barrier molecules and doubly enhancing barrier properties. The organo-montmorillonite-polyamide graft copolymer, through maleic anhydride grafting of polyethylene glycol to form ester bonds with the PETG molecular chains, solves the problems of poor compatibility and easy aggregation of traditional montmorillonite with PETG. Furthermore, the similarity in ester bond structure between polyamide and PETG achieves molecular-level compatibility, avoiding performance degradation caused by phase separation. The lamellar structure of montmorillonite is an inorganic rigid phase, forming physical crosslinking points with the PETG molecular chains, restricting the thermal motion of the PETG molecular chains, increasing the molecular chain modulus and thermal stability, thereby improving tensile strength and heat distortion temperature. Simultaneously, physical crosslinking reduces dimensional shrinkage of PETG during processing and use, improving the dimensional stability of the packaging.

[0018] This invention modifies polyester elastomers by grafting double-bonded UV-absorbing units onto the molecular chains of polyester thermoplastic elastomers via free radical reactions, forming covalent bonds for fixation. This eliminates the need for free UV absorbers, achieving permanent UV protection. The UV-absorbing units efficiently absorb UV light, converting light energy into heat energy, thus blocking UV-induced chain breakage of PETG molecules and decomposition of active ingredients in cosmetics. Simultaneously, it prevents UV absorbers from migrating into cosmetics and affecting product safety. The hard segments of the polyester thermoplastic elastomer have a similar molecular chain structure to PETG, both containing phthalate bonds, achieving molecular-level compatibility with PETG without phase separation. The soft segments, composed of polyether glycol, are flexible chains that form elastic microdomains within the PETG matrix. When subjected to impact loads, these elastic microdomains absorb impact energy, triggering... Silver streaks and shear bands prevent crack propagation, significantly improving room temperature / low temperature impact strength and elongation at break, especially addressing the traditional defects of PETG's low-temperature brittleness; UV-absorbing units can block the free radical chain aging reaction induced by ultraviolet rays, reducing the cross-linking and chain breakage of PETG molecular chains; at the same time, the soft segment of polyester thermoplastic elastomer, polyether glycol, can alleviate the rigidification and embrittlement of PETG molecular chains during aging, maintaining the toughness of the packaging, thereby improving the impact strength retention rate after aging and inhibiting yellowing; the soft segment of polyester thermoplastic elastomer can reduce the melt viscosity of PETG, improve processing fluidity, and reduce defects such as shrinkage marks and bubbles during injection molding and blow molding, while having excellent compatibility with PETG, without agglomeration, ensuring the transparency of the packaging.

[0019] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1

[0022] An organo-montmorillonite-polyamide graft copolymer is prepared by sodium-modifying montmorillonite and organic quaternary ammonium salts to achieve layer exfoliation, followed by in-situ polymerization with polyamide monomers. Simultaneously, a bifunctional grafting agent is introduced to covalently graft the montmorillonite layers onto the polyamide molecular chains. The preparation method includes the following steps: (1) Add 20g of montmorillonite to 200mL of deionized water, stir at high speed for 30min to form a uniform montmorillonite suspension, slowly add 50mL of saturated sodium chloride solution, heat to 85℃, stir at constant temperature for 4h, filter after the reaction is completed, wash with deionized water 3-5 times, dry under vacuum and grind through a 200-mesh sieve to obtain sodium-based montmorillonite. (2) Add 20g of sodium montmorillonite to 200mL of deionized water, stir at high speed for 30min to form a uniform sodium montmorillonite suspension, heat to 80℃, slowly add 5g of cetyltrimethylammonium bromide, stir at constant temperature for 3h, filter after the reaction is completed, wash with anhydrous ethanol 3-5 times, dry under vacuum and grind through a 200-mesh sieve to obtain organo-modified montmorillonite; (3) Add 20g of organo-modified montmorillonite, 40g of m-phenylenediamine, 30g of adipic acid, and 3g of maleic anhydride-grafted polyethylene glycol to the polymerization reactor, add 5mL of deionized water, heat to 60℃ under a nitrogen atmosphere, and stir for 1h. (4) Heat to 180℃, dehydrate under normal pressure for 2 hours, gradually heat to 240℃, reduce pressure to ≤5kPa, melt polycondense for 3 hours, stop the reaction when the melt becomes stringy, cool down to 100℃ under nitrogen atmosphere, extrude the product into granules, and vacuum dry at 80℃ for 12 hours to obtain the organic montmorillonite polyamide graft copolymer.

[0023] Example 2 A modified polyester elastomer, wherein a benzotriazole-based ultraviolet absorbing unit containing a double bond is grafted onto the molecular chain via a free radical grafting reaction using a polyester thermoplastic elastomer as the base material, is prepared by the following steps: A. 900g of polyester thermoplastic elastomer (TPEE), 100g of 2-hydroxy-4-propenoxybenzophenone, and 10g of trimethylolpropane triacrylate were vacuum dried to remove moisture, and 10g of benzoyl peroxide was dissolved in 50mL of anhydrous ethanol. B. The dried polyester thermoplastic elastomer (TPEE), 2-hydroxy-4-propenoxybenzophenone, trimethylolpropane triacrylate, and 2g of antioxidant 1076 are added from the main feed port of the twin-screw extruder. Benzoyl peroxide ethanol solution is continuously injected from the side feed port. The screw diameter is 30mm, the length-to-diameter ratio L / D=40, the temperatures of each zone are 160℃, 180℃, 200℃, 210℃, and 200℃ respectively, the screw speed is 200r / min, and the vacuum degree is ≤-0.09MPa. The materials are melted and mixed in the screw, and a free radical grafting reaction occurs. Ethanol and reaction byproducts are removed under vacuum. C. The extruded melt is cooled with water, pelletized, and vacuum dried at 80°C for 8-12 hours to obtain the modified polyester elastomer.

[0024] Example 3 A cosmetic packaging material based on modified polyester comprises the following raw materials in parts by weight: 85 parts PETG resin, 6 parts organomontmorillonite polyamide graft copolymer, 3 parts modified polyester elastomer, 0.2 parts antioxidant 1010, 0.2 parts antioxidant 168, 0.1 parts sorbitol nucleating agent, 0.1 parts magnesium stearate, and 0.01 parts nano-silica with a particle size of 10-20 nm; the organomontmorillonite polyamide graft copolymer is prepared in Example 1; and the modified polyester elastomer is prepared in Example 2.

[0025] The above-mentioned method for preparing cosmetic packaging materials based on modified polyester includes the following steps: S1. Mix all the raw materials of the modified polyester-based cosmetic packaging material evenly according to the formula ratio, and vacuum dry at 120℃ for 8 hours; S2. Extrusion granulation was carried out using a twin-screw extruder with zone temperatures of 250℃, 260℃, 270℃, 265℃, and 260℃, screw speed of 300 r / min, vacuum degree ≤ -0.09 MPa, water-cooled pelletizing, and vacuum drying at 100℃ for 3 h to obtain cosmetic packaging materials based on modified polyester.

[0026] Example 4 A cosmetic packaging material based on modified polyester comprises the following raw materials in parts by weight: 90 parts PETG resin, 4 parts organomontmorillonite polyamide graft copolymer, 5 parts modified polyester elastomer, 0.1 parts antioxidant 1010, 0.1 parts antioxidant 168, 0.3 parts aryl phosphate salt nucleating agent, 0.01 parts zinc stearate, and 0.1 parts nano-silica with a particle size of 10-20 nm; the organomontmorillonite polyamide graft copolymer is prepared in Example 1; and the modified polyester elastomer is prepared in Example 2.

[0027] The above-mentioned method for preparing cosmetic packaging materials based on modified polyester includes the following steps: S1. Mix all the raw materials of the modified polyester-based cosmetic packaging material evenly according to the formula ratio, and vacuum dry at 120℃ for 6 hours; S2. Extrusion granulation was carried out using a twin-screw extruder with zone temperatures of 250℃, 260℃, 270℃, 265℃, and 260℃, screw speed of 300 r / min, vacuum degree ≤ -0.09 MPa, water-cooled pelletizing, and vacuum drying at 100℃ for 5 h to obtain cosmetic packaging materials based on modified polyester.

[0028] Example 5 A cosmetic packaging material based on modified polyester comprises the following raw materials in parts by weight: 88 parts PETG resin, 5 parts organomontmorillonite polyamide graft copolymer, 4 parts modified polyester elastomer, 0.15 parts antioxidant 1010, 0.15 parts antioxidant 168, 0.2 parts sorbitol nucleating agent, 0.05 parts calcium stearate, and 0.05 parts nano-silica with a particle size of 10-20 nm; the organomontmorillonite polyamide graft copolymer is prepared in Example 1; and the modified polyester elastomer is prepared in Example 2.

[0029] The above-mentioned method for preparing cosmetic packaging materials based on modified polyester includes the following steps: S1. Mix all raw materials for cosmetic packaging materials based on modified polyester according to the formula ratio, and vacuum dry at 120℃ for 7 hours; S2. Extrusion granulation was carried out using a twin-screw extruder with temperatures of 250℃, 260℃, 270℃, 265℃, and 260℃ in each zone, screw speed of 300 r / min, vacuum degree ≤ -0.09 MPa, water-cooled pelletizing, and vacuum drying at 100℃ for 4 h to obtain cosmetic packaging materials based on modified polyester.

[0030] Comparative Example 1 A cosmetic packaging material based on modified polyester comprises the following raw materials in parts by weight: 88 parts PETG resin, 5 parts organomontmorillonite polyamide graft copolymer, 4 parts modified polyester elastomer, 0.3 parts antioxidant 1010 and antioxidant 168, 0.2 parts sorbitol nucleating agent or aryl phosphate salt nucleating agent, 0.05 parts magnesium stearate, zinc stearate and calcium stearate, and 0.05 parts nano-silica with a particle size of 10-20 nm; the modified polyester elastomer is prepared in Example 2.

[0031] The preparation method of the above-mentioned cosmetic packaging material based on modified polyester is the same as that in Example 5, except that the organic montmorillonite polyamide graft copolymer is not added during the mixing in step S1.

[0032] Comparative Example 2 A cosmetic packaging material based on modified polyester comprises the following raw materials in parts by weight: 88 parts PETG resin, 5 parts organomontmorillonite polyamide graft copolymer, 4 parts modified polyester elastomer, 0.3 parts antioxidant 1010 and antioxidant 168, 0.2 parts sorbitol nucleating agent or aryl phosphate salt nucleating agent, 0.05 parts magnesium stearate, zinc stearate and calcium stearate, and 0.05 parts nano-silica with a particle size of 10-20 nm; the organomontmorillonite polyamide graft copolymer is prepared in Example 1.

[0033] The preparation method of the above-mentioned cosmetic packaging material based on modified polyester is the same as that in Example 5, except that modified polyester elastomer is not added during the mixing process in step S1.

[0034] Performance testing The barrier properties, weather resistance and mechanical properties of the modified polyester-based cosmetic packaging materials prepared in Example 5, Comparative Example 1 and Comparative Example 2 were tested.

[0035] (1) Barrier test The oxygen permeability (OTR) was tested according to GB / T19789-2005 "Test for oxygen permeability of plastic films and sheets for packaging materials - coulometric method"; the results are shown in Table 1 below.

[0036] Table 1. Barrier Properties Test Results of Cosmetic Packaging Materials

[0037] As can be seen from the data in Table 1, Example 5 has good oxygen permeability and water vapor permeability, reaching a high barrier level, which can meet the storage requirements of highly active cosmetics for more than 36 months. The barrier properties of Comparative Example 1 decreased significantly, approaching those of conventional PETG, indicating that the organomontmorillonite-polyamide graft copolymer is the core modifier for improving barrier properties. After removal, the barrier properties are completely lost. The barrier properties of Comparative Example 2 decreased only slightly, approaching those of Example 5, indicating that the modified polyester elastomer does not make a significant contribution to the barrier properties, and the two have no synergistic or antagonistic effects.

[0038] (2) Mechanical property testing Tensile strength and elongation at break were tested according to GB / T1040.2-2006 "Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics", notched impact strength of cantilever beams was tested according to GB / T1843-2008 "Determination of impact strength of cantilever beams of plastics", and heat deflection temperature (HDT) was tested according to GB / T1634.2-2004 "Determination of temperature of deformation under load of plastics - Part 2: Plastics, hard rubber and long fiber reinforced composites". The results are shown in Table 2 below.

[0039] Table 2. Test results of mechanical properties of cosmetic packaging materials

[0040] As shown in Table 2, Example 5 exhibits good rigidity, with significantly improved tensile strength and heat distortion temperature compared to conventional PETG. Comparative Example 1 shows a decrease in tensile strength to 58.5 MPa and a decrease in heat distortion temperature to 80.5 °C, while Comparative Example 2 maintains essentially unchanged rigidity. This indicates that the organo-montmorillonite-polyamide graft copolymer is the core component for improving the rigidity and thermal stability of PETG. Its layered structure binds to the PETG molecular chains, forming physical cross-linking points and enhancing the intermolecular forces. Example 5 also demonstrates high toughness, with higher room-temperature and low-temperature impact strength than conventional PETG. Comparative Example 2 shows room-temperature impact strength close to that of conventional PETG, while Comparative Example 1 shows only a slight decrease in toughness. This indicates that the modified polyester elastomer is the core component for improving the toughness of PETG, especially its low-temperature impact resistance. Example 5 has a higher elongation at break than Comparative Examples 1 and 2, demonstrating a synergistic enhancement effect between the improved rigidity of the organo-montmorillonite-polyamide graft copolymer and the toughening modification of the modified polyester elastomer, avoiding the traditional shortcoming of decreased toughness due to increased rigidity.

[0041] (3) Weather resistance test Water vapor transmission rate (WVTR) was measured according to GB / T26253-2010 "Determination of Water Vapor Transmittance of Plastic Films and Sheets - Infrared Detector Method". Ultraviolet light transmittance and haze were measured according to GB / T2410-2021 "Determination of Light Transmittance and Haze of Transparent Plastics", with a test wavelength of 280~400nm. Weather resistance was tested according to GB / T16422.2-2014 "Laboratory Light Source Exposure Test Methods for Plastics - Part 2: Xenon Arc Lamp", with an aging period of 1000h, and yellowing was detected. The retention rates of the index and impact strength were determined. Additive migration was tested according to GB4806.7-2016 "Plastic Materials and Products for Food Contact," using a food-simulated solution (4% acetic acid, n-hexane, and water), immersing at 60℃ for 10 days, and then analyzed by gas chromatography-mass spectrometry (GC-MS). For chemical resistance testing, samples were immersed in common cosmetic solvents (50% propylene glycol, 10% ethanol, and fragrance-simulated solution) at 25℃ for 30 days, and the appearance was observed. Tensile strength retention was also measured. The results are shown in Table 3 below.

[0042] Table 3 Weather resistance test results of cosmetic packaging materials

[0043] As shown in Table 3, the UV transmittance of Example 5 and Comparative Example 1 is ≤3.0%, achieving full-band UV blocking. The UV transmittance of Comparative Example 2 is close to that of conventional PET, indicating that the modified polyester elastomer is the only UV-resistant modifier. Its grafted UV-absorbing units can efficiently absorb 280~400nm UV light, preventing the degradation of PET molecular chains and cosmetic active ingredients by UV rays. After aging for 1000h, Example 5 has a yellowing index of only 1.2 and an impact strength retention rate of 92.5%, with no discoloration or cracking. Comparative Example 2 has a yellowing index of 8.5 and an impact strength retention rate of only 65.3%, showing slight yellowing. This indicates that the modified polyester elastomer can significantly improve the aging resistance of PET. The UV-absorbing units can block the free radical chain reaction caused by UV rays, and the soft segments of the modified polyester elastomer can alleviate the embrittlement of molecular chains during the aging process. The weather resistance of Comparative Example 1 is similar to that of Example 5, indicating that the lamellar structure of the organomontmorillonite-polyamide graft copolymer does not participate in the ultraviolet aging reaction and has no synergistic effect with the modified polyester elastomer in terms of weather resistance.

[0044] The haze of all three groups of samples was significantly lower than that of conventional PETG, indicating that the addition of organo-montmorillonite polyamide graft copolymer and modified polyester elastomer did not affect the transparency of PETG. Furthermore, the compounded nucleating agent ensured uniform crystallization, and the processing was free of defects such as shrinkage marks and bubbles, making it suitable for industrial injection molding and blow molding. No additive migration was detected in any of the three groups of samples, meeting the GB4806.7-2016 standard. This indicates that both the organo-montmorillonite polyamide graft copolymer and the modified polyester elastomer have covalent graft structures, with no free additive precipitation, thus solving the migration problem of traditional small molecule additives. After immersion in common cosmetic solvents for 30 days, all three groups of samples showed no discoloration, swelling, or cracking, and the tensile strength retention rate was ≥97%. This indicates that the addition of organo-montmorillonite polyamide graft copolymer and modified polyester elastomer improved the chemical resistance of PETG. The polyamide structure of the organo-montmorillonite polyamide graft copolymer and the ester bond structure of the modified polyester elastomer enhance resistance to alcohols, esters, and fragrances, making it suitable for various cosmetic solvent systems.

[0045] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0046] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A cosmetic packaging material based on modified polyester, characterized in that, The raw materials include the following parts by weight: 85-90 parts PETG resin, 4-6 parts organomontmorillonite-polyamide graft copolymer, 3-5 parts modified polyester elastomer, 0.2-0.4 parts antioxidant, 0.1-0.3 parts nucleating agent, 0.01-0.1 parts lubricant, and 0.01-0.1 parts antiblocking agent; The organomontmorillonite-polyamide graft copolymer is prepared by sodium-modifying montmorillonite and modifying it with organic quaternary ammonium salt to achieve sheet exfoliation, followed by in-situ polymerization with polyamide monomers. At the same time, a bifunctional grafting agent is introduced to form covalent bonds between the montmorillonite sheets and the polyamide molecular chains. The modified polyester elastomer uses polyester thermoplastic elastomer as the base material and grafts benzotriazole ultraviolet absorption units containing double bonds onto the molecular chain through a free radical grafting reaction.

2. The cosmetic packaging material based on modified polyester according to claim 1, characterized in that, The antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:

1.

3. The cosmetic packaging material based on modified polyester according to claim 1, characterized in that, The nucleating agent is a sorbitol-based nucleating agent or an aryl phosphate salt nucleating agent.

4. The cosmetic packaging material based on modified polyester according to claim 1, characterized in that, The lubricant is one of magnesium stearate, zinc stearate, and calcium stearate.

5. The cosmetic packaging material based on modified polyester according to claim 1, characterized in that, The anti-blocking agent is nano-silica with a particle size of 10~20nm.

6. The cosmetic packaging material based on modified polyester according to claim 1, characterized in that, The preparation method of the organomontmorillonite polyamide graft copolymer includes the following steps: (1) Add montmorillonite to deionized water and stir at high speed for 20-40 min to form a uniform montmorillonite suspension. Slowly add saturated sodium chloride solution, heat to 85℃, stir at constant temperature for 3-5 h, filter after reaction, wash with deionized water 3-5 times, dry under vacuum and grind through a 200 mesh sieve to obtain sodium-based montmorillonite. (2) Add sodium montmorillonite to deionized water and stir at high speed for 20-40 min to form a uniform sodium montmorillonite suspension. Heat to 80℃ and slowly add hexadecyltrimethylammonium bromide. Stir at constant temperature for 2-4 h. After the reaction is complete, filter and wash with anhydrous ethanol 3-5 times. After vacuum drying, grind through a 200-mesh sieve to obtain organo-modified montmorillonite. (3) Add organo-modified montmorillonite, m-phenylenediamine, adipic acid, and maleic anhydride-grafted polyethylene glycol to the polymerization reactor, add a small amount of deionized water, heat to 60°C under a nitrogen atmosphere, and stir for 0.5~1.5h; (4) Heat to 180℃, dehydrate under normal pressure for 1.5~2.5h, gradually heat to 240℃, reduce pressure to ≤5kPa, melt polycondense for 2~4h, stop the reaction when the melt becomes stringy, cool down to 100℃ under nitrogen atmosphere, extrude the product into granules, and vacuum dry at 80℃ for 12h to obtain the organic montmorillonite polyamide graft copolymer.

7. The cosmetic packaging material based on modified polyester according to claim 6, characterized in that, The mass ratio of sodium montmorillonite to hexadecyltrimethylammonium bromide is 4:1; The mass ratio of the organo-modified montmorillonite, m-phenylenediamine, oxalic acid, and maleic anhydride-grafted polyethylene glycol is 2:4:3:0.

3.

8. The cosmetic packaging material based on modified polyester according to claim 1, characterized in that, The method for preparing the modified polyester elastomer includes the following steps: A. The polyester thermoplastic elastomer, 2-hydroxy-4-propenoxybenzophenone, and trimethylolpropane triacrylate were dried under vacuum to remove moisture, and benzoyl peroxide was dissolved in anhydrous ethanol. B. The dried polyester thermoplastic elastomer, 2-hydroxy-4-propenoxybenzophenone, trimethylolpropane triacrylate, and antioxidant 1076 are added from the main feed port of the twin-screw extruder, and the benzoyl peroxide ethanol solution is continuously injected from the side feed port. The materials are melted and mixed in the screw and undergo a free radical grafting reaction. Ethanol and reaction byproducts are removed under vacuum. C. The extruded melt is cooled with water, pelletized, and vacuum dried at 80°C for 8-12 hours to obtain the modified polyester elastomer.

9. The cosmetic packaging material based on modified polyester according to claim 8, characterized in that, The mass ratio of the polyester thermoplastic elastomer to 2-hydroxy-4-propenoxybenzophenone is 9:1; The amounts of trimethylolpropane triacrylate and benzoyl peroxide added are both 1-1.2% of the total mass of the PETE polyester elastomer. The amount of antioxidant 1076 added is 0.2-0.4% of the total mass of PETE polyester elastomer; The screw has a diameter of 30mm, an aspect ratio of L / D=40, and temperatures in each zone are 160℃, 180℃, 200℃, 210℃, and 200℃ respectively. The screw speed is 200r / min, and the vacuum degree is ≤-0.09MPa.

10. The method for preparing cosmetic packaging material based on modified polyester as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Mix all the raw materials of the modified polyester-based cosmetic packaging material evenly according to the formula ratio, and vacuum dry at 120℃ for 6~8h; S2. Extrusion granulation was carried out using a twin-screw extruder with zone temperatures of 250℃, 260℃, 270℃, 265℃, and 260℃, screw speed of 300 r / min, vacuum degree ≤ -0.09 MPa, water-cooled pelletizing, and vacuum drying at 100℃ for 3~5 h to obtain cosmetic packaging materials based on modified polyester.

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