An ultraviolet aging resistant packaging bag material and a preparation method thereof

Abstract

The application relates to the technical field of high polymer composite materials, in particular to an ultraviolet aging resistant packaging bag material and a preparation method thereof. The raw materials of the packaging bag material include the following components in parts by weight: modified polybutylene terephthalate / hexanedioic acid butanediol ester 60-80 parts, polylactic acid 10-30 parts, polycaprolactone 5-15 parts, antioxidant 1-3 parts, plasticizer 5-10 parts and nano inorganic filler 5-10 parts. The packaging bag material has excellent ultraviolet aging resistance, durable antibacterial ability and mechanical properties, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, specifically to an anti-ultraviolet aging packaging bag material and its preparation method. Background Technology

[0002] With the widespread use of single-use plastic products in food packaging, the resulting "white pollution" problem is becoming increasingly serious. Traditional petroleum-based plastics such as polyethylene (PE) and polypropylene (PP) are difficult to degrade in the natural environment, causing irreversible damage to soil and aquatic ecosystems over a long period. Against this backdrop, the development of polymer packaging materials that combine performance and biodegradability has become an industry consensus. Currently, the more mature biodegradable plastics under research mainly include polylactic acid (PLA), polybutylene terephthalate (PBAT), and polycaprolactone (PCL). To compensate for the performance deficiencies of single components, blending PBAT with biodegradable polyesters such as PLA and PCL has become the mainstream technical route. Among them, PBAT, due to its combination of the flexibility of aliphatic polyesters and the mechanical strength of aromatic polyesters, is considered one of the most promising biodegradable materials to replace traditional plastics and has been widely used in shopping bags, garbage bags, food packaging bags, and agricultural mulch films.

[0003] However, PBAT faces a dual challenge in practical applications: on the one hand, it lacks sufficient mechanical strength and antibacterial activity, making it prone to bacterial and mold growth in humid environments; on the other hand, the aromatic and aliphatic ester bonds in the PBAT molecular chain are susceptible to photo-oxidative degradation under ultraviolet light, leading to rapid decline in mechanical properties, yellowing, and embrittlement, severely limiting its application in outdoor composting bags, agricultural mulch films, and other applications requiring long-term exposure to sunlight. Therefore, how to simultaneously endow PBAT with multiple functions such as UV resistance, antibacterial properties, and mechanical enhancement while maintaining its biodegradability is a key technical problem that urgently needs to be solved in this field.

[0004] In terms of UV-resistant modification, existing technologies typically employ physical blending of organic or inorganic UV absorbers. CN122037504A discloses a modified novel material-based UV-resistant woven plastic bag, using a composite of sheet-like nano-titanium dioxide and nano-cerium oxide as a UV shielding agent, and improving dispersibility through surface treatment with a silane coupling agent. While this approach can improve the UV blocking rate to some extent, the interfacial compatibility between inorganic nanoparticles and the PBAT matrix is ​​limited. Under long-term UV irradiation, interfacial debonding and particle aggregation still easily occur, leading to a decline in UV resistance. Furthermore, purely physically blended UV absorbers are prone to migration and loss on the material surface, making it difficult to achieve long-lasting UV protection.

[0005] In terms of antibacterial modification, existing technologies mostly rely on physical blending of inorganic or organic antibacterial agents. For example, CN120365716B discloses a biodegradable antibacterial plastic packaging bag that uses Cr and Cu co-modified ZIF-8 and cerium tannate oxide as antibacterial active components. Although this approach can achieve a certain antibacterial effect, the interfacial compatibility between ZIF-8 and other metal-organic framework materials and the polyester matrix is ​​poor, and agglomeration is prone to occur during melt processing, leading to a decrease in antibacterial efficiency and a significant increase in cost. At the same time, this approach does not optimize the chemical structure of the PBAT matrix itself; the improvement of antibacterial performance and UV resistance is independent and lacks a synergistic mechanism, and it does not involve UV aging resistance.

[0006] Therefore, developing a biodegradable packaging bag material that combines excellent UV aging resistance, high-efficiency antibacterial properties, and good mechanical properties is of great significance for promoting the industrial application of green packaging materials. Summary of the Invention

[0007] The purpose of this invention is to provide an anti-UV aging packaging bag material and its preparation method, thereby solving the technical problems of poor anti-UV aging performance, insufficient antibacterial properties, and difficulty in simultaneously achieving mechanical and functional properties in existing packaging materials. To achieve the above objective, this invention adopts the following technical solution: An anti-ultraviolet aging packaging bag material, comprising the following raw materials by weight: 60-80 parts of modified poly(butylene terephthalate) / (butylene adipate) 10-30 parts of polylactic acid 5-15 parts of polycaprolactone 1-3 parts antioxidant 5-10 parts plasticizer 5-10 parts of nano-inorganic filler The modified poly(butylene terephthalate) / poly(adipate) is prepared by esterification and polycondensation reaction of terephthalic acid, adipic acid, 1,4-butanediol and modifier X in the presence of a catalyst. The structural formula of the modifier X is: .

[0008] Preferably, the antioxidant is selected from one or more of antioxidant 1010, antioxidant 168, antioxidant 1076, antioxidant 1098, antioxidant 264 and antioxidant DLTP.

[0009] Preferably, the nano-inorganic filler is selected from one or more of nano-zinc oxide, nano-titanium dioxide and nano-alumina, with a particle size of 20~60nm.

[0010] Preferably, the plasticizer is selected from one or more of the following: tributyl citrate, triethyl citrate, acetylated tributyl citrate, polyethylene glycol, epoxidized soybean oil, and glycerin. Preferably, the molar ratio of 1,4-butanediol to adipic acid is (2~4):1; the molar ratio of 1,4-butanediol to terephthalic acid is (2~4):1; the molar ratio of modifier X to 1,4-butanediol is (0.05~0.2):1; the molar ratio of catalyst to 1,4-butanediol is (0.01~0.05):1; and the molar amount of 1,4-butanediol is equal to the total molar amount of terephthalic acid, adipic acid, and modifier X.

[0011] Preferably, the catalyst is tetrabutyl titanate or antimony glycolate; Preferably, the preparation method of the modified poly(butylene terephthalate) / poly(dibutyl adipate) includes the following steps: In an inert gas environment, terephthalic acid, adipic acid, 1,4-butanediol, and modifier X undergo esterification at 180–230 °C and atmospheric pressure under the action of a catalyst. Then, the temperature is raised to 240–260 °C, and polycondensation is carried out at a pressure of 0–60 Pa to obtain modified polyterephthalic acid / butylene adipate.

[0012] This invention also provides a method for preparing the aforementioned UV-resistant packaging bag material, comprising the following steps: Modified polybutylene terephthalate / adipate, polylactic acid, polycaprolactone, antioxidant, plasticizer, and nano-inorganic filler are mixed evenly and then added to a twin-screw extruder for melt blending and granulation to obtain granules. The granules are dried and then blown into films in a blown film machine. After slitting and heat sealing, the films are made into bags to obtain UV-resistant packaging bag materials.

[0013] Preferably, the temperature settings of each zone of the twin-screw extruder are as follows: zone 1 140-150℃, zone 2 155-165℃, zone 3 165-175℃, zone 4 170-180℃, and zone 5 175-185℃, and the screw speed is 100-300 rpm; the blow-up ratio of the blown film extruder is 2.0-4.0, the traction speed is 8-15 m / min, and the die temperature is 140-170℃.

[0014] 1) This invention introduces a modifier X containing a triazole ring, quaternary ammonium salt group, and pyridine ring in situ during the PBAT copolymerization reaction. This allows the organic antibacterial functional groups to be chemically bonded to the PBAT molecular chain, rather than through simple physical blending. This chemical bonding method not only significantly improves the dispersibility and stability of the antibacterial functional groups in the matrix, avoiding the problems of easy migration and precipitation of traditional physically blended antibacterial agents, but also, through the synergistic effect of the triazole ring, pyridine ring, quaternary ammonium salt group, and nano-inorganic fillers (zinc oxide and titanium dioxide also have antibacterial properties), endows the material with highly efficient and long-lasting antibacterial properties. The packaging bag material of this invention achieves an antibacterial rate of over 99.9% against Staphylococcus aureus and Escherichia coli.

[0015] 2) The triazole ring and pyridine ring in the modifier X of this invention form a nitrogen-containing conjugated system that can absorb ultraviolet light; at the same time, its nitrogen-rich structure promotes the uniform dispersion of nano zinc oxide through coordination and forms an organic-inorganic composite ultraviolet shielding layer in synergy with nano zinc oxide, so that the packaging bag material retains a tensile strength of up to 90% after accelerated ultraviolet aging and the yellowing index (ΔYI) is as low as 2.7.

[0016] 3) This invention employs a PBAT / PLA / PCL ternary blend system. Polylactic acid improves the rigidity and strength of the material, while polycaprolactone enhances its flexibility and processability. The synergistic effect of these three components gives the material both excellent mechanical and processing properties. Simultaneously, the introduction of modifier X further strengthens the interactions between molecular chains, forming a physical cross-linking network and improving the material's mechanical properties. Detailed Implementation

[0017] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] The endpoints and any values ​​of the ranges described in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. The raw materials and reagents used in the following examples are commercially available.

[0019]

[0020] Compound 1 (0.1 mol), compound 2 (0.15 mol), copper acetylacetonate (0.01 mol), 4,7-dichloro-1,10-phenanthroline (0.01 mol), and methanol (150 mL) were added to a reactor and stirred at room temperature for 12 h. After the reaction was completed, the mixture was filtered, the filter cake was washed with cold methanol, and dried under vacuum to obtain intermediate compound 3, with a yield of 95.7%.

[0021] Intermediate compound 3 (0.1 mol) was dissolved in deionized water (100 mL), and then lithium hydroxide (0.6 mol) was added. The mixture was stirred at room temperature for 24 hours. After the reaction was completed, the pH of the solution was adjusted to 4.0 with dilute HCl. After removing half of the solvent under reduced pressure, acetone was added to precipitate the solid. The solid was filtered, and the filter cake was dried under vacuum to obtain modifier X as a white solid with a yield of 93.1%.

[0022] 1 H NMR (400 MHz, DMSO- d 6) δ (ppm) 9.61 (1H, s), 8.78 (2H, s), 4.82 (2H, s), 3.11 (9H, s); HRMS-ESI m / z: [M-Cl] + =306.1201.

[0023] Example 1: A method for preparing an anti-UV aging packaging bag material, comprising the following steps:

[0024] 1,4-Butanediol (4.6 mol), adipic acid (2.0 mol), terephthalic acid (2.0 mol), modifier X (0.6 mol), and catalyst tetrabutyl titanate (0.1 mol) were added to a reactor and stirred until homogeneous. The mixture was purged with nitrogen three times and stirred for 2 hours at 300 rpm, 220°C, and atmospheric pressure. The temperature was then raised to 250°C, and the reaction was continued for 3 hours at 30 Pa. After the reaction, nitrogen was introduced into the reactor to restore atmospheric pressure, yielding PBAT melt. This melt was extruded under nitrogen protection, cooled to room temperature, and granulated to obtain modified polybutylene terephthalate (PET).

[0025] Accurately weigh 80 parts by weight of modified polybutylene terephthalate (obtained in step 1), 20 parts of polylactic acid (NatureWorks, USA, grade 4032D), 10 parts of polycaprolactone (Perstorg, Sweden, grade Capa6500), 1 part of antioxidant 1010, 10 parts of tributyl citrate, and 10 parts of nano zinc oxide (particle size 30nm). The above raw materials were mixed in a high-speed mixer for 10 minutes, and then added to a twin-screw extruder for melt blending and granulation. The temperature settings of each zone of the twin-screw extruder were: zone 1 145℃, zone 2 160℃, zone 3 170℃, zone 4 175℃, and zone 5 180℃, with a screw speed of 200 rpm. After the extruded granules were vacuum dried at 60℃ for 8 hours, they were fed into a single-screw blown film extruder for blow molding. The blow-up ratio was 3.0, the traction speed was 10 m / min, and the die temperature was 150℃ to obtain a plastic film. The plastic film was then slit and heat-sealed to make bags, resulting in UV-resistant packaging bag material.

[0026] Example 2: A method for preparing an anti-UV aging packaging bag material, comprising the following steps:

[0027] 1,4-Butanediol (4.5 mol), adipic acid (2.0 mol), terephthalic acid (2.0 mol), modifier X (0.5 mol), and catalyst tetrabutyl titanate (0.1 mol) were added to a reactor and stirred until homogeneous. The mixture was purged with nitrogen three times and stirred for 3 hours at 300 r / min, 200 °C, and atmospheric pressure. The temperature was then raised to 250 °C, and the reaction was continued for another 3 hours at 50 Pa. After the reaction was complete, nitrogen was introduced into the reactor to restore atmospheric pressure, yielding PBAT melt. This melt was extruded under nitrogen protection, cooled to room temperature, and granulated to obtain modified polybutylene terephthalate (PET).

[0028] Accurately weigh 70 parts by weight of modified polybutylene terephthalate (obtained in step 1), 25 parts of polylactic acid (NatureWorks, USA, grade 4032D), 15 parts of polycaprolactone (Perstorg, Sweden, grade Capa6500), 2 parts of antioxidant 168, 10 parts of triethyl citrate, and 10 parts of nano titanium dioxide (particle size 50nm). The above raw materials were mixed in a high-speed mixer for 10 minutes, and then added to a twin-screw extruder for melt blending and granulation. The temperature settings of each zone of the twin-screw extruder were: zone 1 145℃, zone 2 160℃, zone 3 170℃, zone 4 175℃, and zone 5 180℃, with a screw speed of 200 rpm. After the extruded granules were vacuum dried at 60℃ for 8 hours, they were fed into a single-screw blown film extruder for blow molding. The blow-up ratio was 3.5, the traction speed was 8 m / min, and the die temperature was 150℃ to obtain a plastic film. The plastic film was then slit and heat-sealed to make bags, resulting in UV-resistant packaging bag material.

[0029] Example 3: A method for preparing an anti-UV aging packaging bag material, comprising the following steps:

[0030] 1,4-Butanediol (4.6 mol), adipic acid (2.0 mol), terephthalic acid (2.0 mol), modifier X (0.6 mol), and catalyst tetrabutyl titanate (0.1 mol) were added to a reactor and stirred until homogeneous. The mixture was purged with nitrogen three times and stirred for 2 hours at 300 rpm, 220°C, and atmospheric pressure. The temperature was then raised to 250°C, and the reaction was continued for 3 hours at 30 Pa. After the reaction, nitrogen was introduced into the reactor to restore atmospheric pressure, yielding PBAT melt. This melt was extruded under nitrogen protection, cooled to room temperature, and granulated to obtain modified polybutylene terephthalate (PET).

[0031] Accurately weigh 75 parts by weight of modified polybutylene terephthalate (obtained in step 1), 20 parts of polylactic acid (NatureWorks, USA, grade 4032D), 15 parts of polycaprolactone (Perstorg, Sweden, grade Capa6500), 1.5 parts of antioxidant 1076, 10 parts of tributyl acetylacetonate, and 10 parts of nano zinc oxide (particle size 30nm). The above raw materials were mixed in a high-speed mixer for 10 minutes, and then added to a twin-screw extruder for melt blending and granulation. The temperature settings of each zone of the twin-screw extruder were: zone 1 145℃, zone 2 160℃, zone 3 170℃, zone 4 175℃, and zone 5 180℃, with a screw speed of 200 rpm. After the extruded granules were vacuum dried at 60℃ for 8 hours, they were fed into a single-screw blown film extruder for blow molding. The blow-up ratio was 3.0, the traction speed was 10 m / min, and the die temperature was 150℃ to obtain a plastic film. The plastic film was then slit and heat-sealed to make bags, resulting in UV-resistant packaging bag material.

[0032] Based on Example 1, the modifier X was replaced with... Other operations and conditions are the same as in Example 1.

[0033] Based on Example 1, the modifier X was replaced with... Other operations and conditions are the same as in Example 1.

[0034] The UV aging resistance and antibacterial properties of the UV-resistant packaging bag materials prepared in Examples 1-3 and Comparative Examples 1-2 were tested using the following methods: Tensile strength: Tested according to GB / T 1040.3-2006; Antibacterial properties: Tested according to QB / T 2591-2003, the test strains were Staphylococcus aureus (ATCC6538) and Escherichia coli (ATCC 25922), and the inoculum concentration was 1.0 × 10⁻⁶. 5 CFU / mL; UV aging resistance: The accelerated aging test under fluorescent UV lamps was conducted according to GB / T 16422.3-2014, using a UV-A340 lamp tube, with a test cycle of 20 days; the tensile strength retention rate and yellowing index (ΔYI, calculated according to ASTM D1925) before and after aging were tested. The test results are shown in Table 1.

[0035] Table 1 Performance Test Results

[0036] As can be seen from the data in Table 1, the UV-resistant packaging bag materials prepared in Examples 1 to 3 of the present invention exhibit significant advantages in terms of mechanical properties, antibacterial properties, and UV-resistant properties.

[0037] Regarding mechanical properties: the tensile strengths of Examples 1-3 were 42.6 MPa, 40.9 MPa, and 41.5 MPa, respectively, all higher than those of Comparative Example 1 (37.3 MPa) and Comparative Example 2 (38.5 MPa). This indicates that the introduction of modifier X not only did not reduce the mechanical properties of the material, but also enhanced the interaction between molecular chains through chemical bonding, forming a physical cross-linked network, thereby improving the tensile strength of the material.

[0038] Regarding UV aging resistance: After 20 days of accelerated aging under UV-A340 lamps, the tensile strength retention rates of Examples 1-3 were 91.1%, 90.4%, and 90.0%, respectively, and the yellowing indices ΔYI were 2.7, 3.0, and 3.1, respectively, all superior to Comparative Example 1 (tensile strength retention rate 76.8%, ΔYI 6.6) and Comparative Example 2 (tensile strength retention rate 66.9%, ΔYI 8.2). This fully demonstrates the synergistic effect of the triazole ring and pyridine ring in modifier X with the nano-inorganic filler, significantly improving the UV aging resistance of the materials.

[0039] Regarding antibacterial properties: Examples 1-3 showed antibacterial rates of 99.95%, 99.91%, and 99.98% against Staphylococcus aureus, respectively, and antibacterial rates of 99.93%, 99.90%, and 99.99% against Escherichia coli, respectively. All of these achieved a highly efficient antibacterial level of over 99.9%, which is superior to Comparative Examples 1 and 2. Furthermore, the introduction of antibacterial properties through chemical bonding ensures the durability and stability of the antibacterial function.

[0040] The above embodiments are merely illustrative examples and are not intended to limit the implementation. Those skilled in the art will recognize that various variations and modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. Therefore, any obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A UV-resistant packaging bag material, characterized in that, By weight, it includes the following ingredients: 60-80 parts of modified poly(butylene terephthalate) / (butylene adipate) 10-30 parts of polylactic acid 5-15 parts of polycaprolactone 1-3 parts antioxidant 5-10 parts plasticizer 5-10 parts of nano-inorganic filler The modified poly(butylene terephthalate) / poly(adipate) is prepared by esterification and polycondensation reaction of terephthalic acid, adipic acid, 1,4-butanediol and modifier X in the presence of a catalyst. The structural formula of the modifier X is: .

2. The UV-resistant packaging bag material according to claim 1, characterized in that, The antioxidant is selected from one or more of antioxidant 1010, antioxidant 168, antioxidant 1076, antioxidant 1098, antioxidant 264 and antioxidant DLTP.

3. The UV-resistant packaging bag material according to claim 1, characterized in that, The nano-inorganic filler is selected from one or more of nano zinc oxide, nano titanium dioxide and nano aluminum oxide, with a particle size of 20~60nm.

4. The UV-resistant packaging bag material according to claim 1, characterized in that, The plasticizer is selected from one or more of the following: tributyl citrate, triethyl citrate, acetylated tributyl citrate, polyethylene glycol, epoxidized soybean oil, and glycerin.

5. The UV-resistant packaging bag material according to claim 1, characterized in that, The molar ratio of 1,4-butanediol to adipic acid is (2~4):1; the molar ratio of 1,4-butanediol to terephthalic acid is (2~4):1; the molar ratio of modifier X to 1,4-butanediol is (0.05~0.2):1; the molar ratio of catalyst to 1,4-butanediol is (0.01~0.05):1; and the molar amount of 1,4-butanediol is equal to the total molar amount of terephthalic acid, adipic acid, and modifier X.

6. The UV-resistant packaging bag material according to claim 1, characterized in that, The catalyst is tetrabutyl titanate or antimony glycol.

7. The UV-resistant packaging bag material according to claim 1, characterized in that, The preparation method of the modified poly(butylene terephthalate) includes the following steps: In an inert gas environment, terephthalic acid, adipic acid, 1,4-butanediol, and modifier X undergo esterification at 180–230 °C and atmospheric pressure under the action of a catalyst. Then, the temperature is raised to 240–260 °C, and polycondensation is carried out at a pressure of 0–60 Pa to obtain modified polyterephthalic acid / butylene adipate.

8. A method for preparing an anti-UV aging packaging bag material according to any one of claims 1 to 7, characterized in that, Includes the following steps: Modified polybutylene terephthalate / adipate, polylactic acid, polycaprolactone, antioxidant, plasticizer, and nano-inorganic filler are mixed evenly and then added to a twin-screw extruder for melt blending and granulation to obtain granules. The granules are dried and then blown into films in a blown film machine. After slitting and heat sealing, the films are made into bags to obtain UV-resistant packaging bag materials.

9. The preparation method according to claim 8, characterized in that, The temperature settings for each zone of the twin-screw extruder are as follows: Zone 1 140–150℃, Zone 2 155–165℃, Zone 3 165–175℃, Zone 4 170–180℃, and Zone 5 175–185℃, with a screw speed of 100–300 rpm; the blown film extruder has a blow-up ratio of 2.0–4.0, a traction speed of 8–15 m / min, and a die temperature of 140–170℃.

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