A high weather-resistant biaxially oriented PP / PE synthetic paper and its preparation method

Abstract

The present invention discloses a highly weather-resistant biaxially stretched PP / PE synthetic paper and its preparation method, belonging to the technical field of synthetic paper. The synthetic paper is composed of an outer layer, an intermediate layer and an inner layer. The outer layer comprises the following raw materials in parts by weight: 40-50 parts of PP, 20-40 parts of PE, 2-5 parts of a modified anti-aging agent, 2-6 parts of calcium carbonate, 2-4 parts of an antibacterial agent, and 1-2 parts of titanium dioxide; the intermediate layer comprises the following raw materials in parts by weight: 30-50 parts of PP, 20-30 parts of PE, 2-6 parts of calcium carbonate, 2-4 parts of an antistatic agent, and 1-2 parts of titanium dioxide; the raw materials and their parts of the inner layer are the same as those of the outer layer. The highly weather-resistant biaxially stretched PP / PE synthetic paper prepared by the present invention has excellent mechanical properties, anti-aging properties and antibacterial properties.

Description

Technical Field

[0001] The present invention relates to the technical field of synthetic paper, and particularly relates to a high-weather-resistant PP / PE biaxially stretched synthetic paper and a preparation method thereof. Background Art

[0002] In today's society, with the continuous progress of technology and the continuous development of industries, the demand for various high-performance materials is increasing day by day. In many material application fields, synthetic paper, as a new material that combines the advantages of paper and plastic film, is gradually attracting wide attention.

[0003] PP (polypropylene) and PE (polyethylene), as two common polyolefin materials, each have unique advantages. PP has high strength, rigidity, excellent heat resistance and chemical corrosion resistance, while PE is favored for its good flexibility, low-temperature resistance and electrical insulation. Combining PP and PE and preparing synthetic paper through a biaxial stretching process is a very promising direction for material research and development.

[0004] However, in practical applications, traditional PP / PE synthetic paper still has certain limitations in terms of weather resistance. When exposed to the outdoor environment for a long time, affected by natural factors such as ultraviolet radiation, wind and rain erosion, and temperature and humidity changes, its performance will gradually decline, such as surface aging, discoloration, cracking, etc., resulting in a shortened service life of the material and being difficult to meet the requirements of some long-term outdoor use scenarios, such as outdoor advertising materials, agricultural covering materials, building waterproof materials and other fields.

[0005] Furthermore, antibacterial performance is also a key issue in the application of synthetic paper. In a humid and warm environment, bacteria and microorganisms are likely to grow on the surface of synthetic paper, which not only poses a threat to the health and safety of products, but may also cause the generation of odors, corrosion of the material surface and further decline in performance.

[0006] Chinese Patent Invention No. CN118205283A discloses a high-density polypropylene synthetic paper and its preparation method and application. The high-density polypropylene synthetic paper includes an outer layer, an intermediate layer and an inner layer. The outer layer includes: polypropylene: 40 - 50 parts, titanium dioxide: 1 - 2 parts, calcium carbonate: 2 - 4 parts, antioxidant: 2 - 3 parts; the intermediate layer includes: polypropylene: 30 - 40 parts, titanium dioxide: 1 - 2 parts, antistatic agent: 2 - 3 parts; the raw materials and their parts of the inner layer are the same as those of the outer layer. This synthetic paper has excellent antioxidant aging performance, but its antibacterial performance is poor. Summary of the Invention

[0007] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a high-weather-resistant PP / PE biaxially stretched synthetic paper and a preparation method thereof.

[0008] To achieve the above object, the present invention is realized through the following technical solutions:

[0009] A highly weather-resistant PP / PE biaxially stretched synthetic paper, which consists of an outer layer, an intermediate layer and an inner layer. The outer layer comprises the following raw materials in parts by weight: PP: 40 - 50 parts, PE: 20 - 40 parts, modified anti-aging agent: 2 - 5 parts, calcium carbonate: 2 - 6 parts, antibacterial agent 2 - 4 parts, titanium dioxide 1 - 2 parts;

[0010] The intermediate layer comprises the following raw materials in parts by weight: PP: 30 - 50 parts, PE: 20 - 30 parts, calcium carbonate: 2 - 6 parts, antistatic agent 2 - 4 parts, titanium dioxide 1 - 2 parts;

[0011] The raw materials and their parts of the inner layer are the same as those of the outer layer;

[0012] The modified anti-aging agent is prepared by the following method:

[0013] S1: L-homocysteine reacts with tetra-armed polyethylene glycol hydroxyl to form a tetra-armed disulfide compound;

[0014] S2: The tetra-armed disulfide compound reacts with 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid under the catalysis of N,N'-dicyclohexylcarbodiimide and 1-hydroxybenzotriazole to form a modified anti-aging agent.

[0015] The feeding mass ratio of L-homocysteine to tetra-armed polyethylene glycol hydroxyl in step S1 is 1:(2 - 2.5).

[0016] The feeding mass ratio of the tetra-armed disulfide compound to 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid in step S2 is (3 - 4):1.

[0017] The antibacterial agent is prepared by the following method:

[0018] A1: 1,14-diazido-3,6,9,12-tetraoxatetradecane reacts with 2-butyn-3-epoxyethane under the action of cuprous bromide to form a triazole ring compound;

[0019] A2: The triazole ring compound reacts with cetyl dimethyl tertiary amine under the action of hydrochloric acid to form an antibacterial agent.

[0020] The feeding molar ratio of 1,14-diazido-3,6,9,12-tetraoxatetradecane to 2-butyn-3-epoxyethane in step A1 is 1:2.

[0021] The feeding molar ratio of the triazole ring compound to cetyl dimethyl tertiary amine in step A2 is 1:2.

[0022] The antistatic agent is one of AS11N antistatic agent and Armostat400 antistatic agent.

[0023] A preparation method of a highly weather-resistant biaxially oriented PP / PE synthetic paper comprises the following steps:

[0024] B1: Extruding the outer layer raw material, the middle layer raw material and the inner layer raw material through an extruder respectively;

[0025] B2: Extruding the raw materials of each layer extruded by the extruder through a T-shaped die head, then performing longitudinal stretching and transverse stretching, and then cooling, corona treatment and edge trimming to obtain the product;

[0026] Among them, the extrusion temperature of the outer layer raw material and the inner layer raw material is 230 °C, and the extrusion temperature of the middle layer raw material is 250 °C; the preheating section temperature of the longitudinal stretching is 130 °C, the stretching section temperature is 142 °C, the shaping section temperature is 145 °C, the longitudinal stretching ratio is 4.9, the preheating section temperature of the transverse stretching is 167 °C, the stretching section temperature is 155 °C, the shaping section temperature is 171 °C, the transverse stretching ratio is 9 times, and the corona treatment is 34.

[0027] Due to the above technical solutions, the beneficial effects of the present invention include:

[0028] (1) The modified anti-aging agent prepared by the present invention has a dual antioxidant mechanism to resist aging. Adding it to the preparation process of the synthetic paper not only enhances the durability of the synthetic paper, but also further extends the material life through the self-healing potential, and the comprehensive performance is superior to that of traditional single-functional anti-aging agents.

[0029] (2) The antibacterial agent prepared by the present invention realizes efficient, broad-spectrum and long-lasting antibacterial performance through the quaternary ammonium salt cation killing mechanism, the stabilization effect of the triazole ring and the membrane-damaging ability of the long-chain alkyl group. Its chemical structure design takes into account antibacterial activity, matrix compatibility and environmental safety, and is especially suitable for synthetic paper application scenarios with high requirements for durability and biological safety. Specific embodiments

[0030] The following is further illustrated with reference to embodiments, but the present invention is not limited to these embodiments.

[0031] Example 1 Preparation of modified anti-aging agent:

[0032] S1: Under nitrogen protection, add 300 ml of toluene and 40 g of tetra-armed polyethylene glycol hydroxyl (M W= 2000), 20 g of L - cystine, stirred and mixed evenly, heated to 80 °C, then 8 g of p - toluenesulfonic acid was added, and after reacting for 6 h (water generated during the reaction was removed using a water separator), it was cooled to room temperature. Saturated sodium bicarbonate solution was slowly added to adjust the pH to neutral, stirred well for 30 min, allowed to stand for layer separation, and the organic phase was transferred to a rotary evaporator and distilled under reduced pressure at 60 °C for 4 h to obtain a four - armed disulfide compound; during this reaction process, the hydroxyl group in the hydroxyl - terminated four - armed polyethylene glycol reacted with the carboxyl group in L - cystine in an esterification reaction;

[0033] S2: At room temperature, 500 ml of anhydrous DMF, 30 g of 3 - (3,5 - di - tert - butyl - 4 - hydroxyphenyl) propionic acid, and 5 g of N,N’ - dicyclohexylcarbodiimide were added to a reactor, stirred for 1 h, then 90 g of the four - armed disulfide compound and 5 g of 1 - hydroxybenzotriazole were added, stirred and mixed evenly, and after reacting at room temperature for 10 h, it was filtered. After distilling under reduced pressure at 60 °C for 2 h, a crude product was obtained. The crude product was dissolved in 200 ml of tetrahydrofuran, 200 ml of a methanol / water mixture (methanol: water (V / V) = 95:5) was added, stirred, a precipitate was formed, filtered, and washed three times with 400 ml of cold hexane. The solid residue was collected and vacuum - dried at 60 °C for 4 h to obtain the modified anti - aging agent; during this reaction process, the amino group in the four - armed disulfide compound reacted with the carboxyl group in 3 - (3,5 - di - tert - butyl - 4 - hydroxyphenyl) propionic acid.

[0034] Example 2 Preparation of the modified anti - aging agent:

[0035] S1: Under nitrogen protection, 300 ml of toluene, 45 g of hydroxyl - terminated four - armed polyethylene glycol (M W = 2000), 20 g of L - cystine were added to a reactor, stirred and mixed evenly, heated to 90 °C, then 8 g of p - toluenesulfonic acid was added, and after reacting for 5 h (water generated during the reaction was removed using a water separator), it was cooled to room temperature. Saturated sodium bicarbonate solution was slowly added to adjust the pH to neutral, stirred well for 30 min, allowed to stand for layer separation, and the organic phase was transferred to a rotary evaporator and distilled under reduced pressure at 60 °C for 4 h to obtain a four - armed disulfide compound;

[0036] S2: At room temperature, add 500 ml of anhydrous DMF, 30 g of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, and 5 g of N,N'-dicyclohexylcarbodiimide into the reactor, stir for 1 h, then add 100 g of tetraarm dithiol compound and 5 g of 1-hydroxybenzotriazole, stir and mix evenly. After reacting for 12 h at room temperature, filter, and obtain the crude product after vacuum distillation at 60 °C for 2 h. The crude product is dissolved in 200 ml of tetrahydrofuran, add 200 ml of methanol / water mixture (methanol: water (V / V) = 95:5), stir, precipitate is separated out, filter, and wash with 400 ml of cold hexane three times. Collect the solid residue and vacuum dry at 60 °C for 4 h to obtain the modified anti-aging agent.

[0037] Example 3 Preparation of modified anti-aging agent:

[0038] S1: Under nitrogen protection, add 300 ml of toluene, 50 g of tetraarm polyethylene glycol hydroxyl (M W = 2000), and 20 g of L-homocysteine into the reactor, stir and mix evenly, heat up to 100 °C, then add 8 g of p-toluenesulfonic acid, react for 4 h (remove the generated water using a water separator during the reaction), then cool to room temperature, slowly add saturated sodium bicarbonate solution to adjust the pH to neutral, stir well for 30 min, let it stand for layering, transfer the organic phase to a rotary evaporator, and vacuum distill at 60 °C for 4 h to obtain the tetraarm dithiol compound;

[0039] S2: At room temperature, add 500 ml of anhydrous DMF, 30 g of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, and 5 g of N,N'-dicyclohexylcarbodiimide into the reactor, stir for 1 h, then add 120 g of tetraarm dithiol compound and 5 g of 1-hydroxybenzotriazole, stir and mix evenly. After reacting for 14 h at room temperature, filter, and obtain the crude product after vacuum distillation at 60 °C for 2 h. The crude product is dissolved in 200 ml of tetrahydrofuran, add 200 ml of methanol / water mixture (methanol: water (V / V) = 95:5), stir, precipitate is separated out, filter, and wash with 400 ml of cold hexane three times. Collect the solid residue and vacuum dry at 60 °C for 4 h to obtain the modified anti-aging agent.

[0040] Example 4 Preparation of antibacterial agent:

[0041] A1: Under airtight conditions, add 200 ml of DMF, 0.1 mol of 1,14-diazido-3,6,9,12-tetraoxatetradecane, and 0.2 mol of 2-butyn-3-epoxyethane to the reactor. Stir and mix well, then add 0.1 mol of cuprous bromide and 0.1 mol of N,N,N′,N′′,N′′-pentamethyldiethylenetriamine. React at room temperature for 24 h, then expose to air for 1 h to quench the reaction. Dialyze in a 2 wt% EDTA DMF solution (MwCO = 8 KDa) for 24 h, and then dialyze in deionized water (MwCO = 8 KDa) for 24 h. Freeze-dry at -20 °C for 5 h to obtain the triazole ring compound; the reaction equation is shown as follows:

[0042]

[0043] A2: Add 400 ml of absolute ethanol, 0.1 mol of the triazole ring compound, 10 ml of 36 wt% hydrochloric acid, and 0.2 mol of cetyl dimethyl tertiary amine to the reactor. Stir and mix well, heat to reflux and react for 40 h, then distill under reduced pressure at 40 °C for 2 h, and then recrystallize three times with acetone (200 ml of acetone each time). Dry in vacuo at 60 °C for 5 h to obtain the antibacterial agent; the reaction equation is shown as follows:

[0044]

[0045] The 1H NMR data are as follows:

[0046] 1 H NMR (500 MHz, Chloroform-d) δ 7.38 (p, J = 0.8 Hz, 2H), 5.91 (d, J = 6.1 Hz, 2H), 4.30 – 4.17 (m, 6H), 3.95 (t, J = 4.2 Hz, 4H), 3.74 – 3.59 (m,14H), 3.50 – 3.36 (m, 6H), 3.32 (s, 6H), 3.19 (s, 6H), 2.89 (dd, J = 49.0,0.9 Hz, 4H), 2.44 – 1.92 (m, 4H), 1.79 – 1.61 (m, 4H), 1.43 – 1.32 (m, 4H),1.31 – 1.19 (m, 48H), 0.98 – 0.81 (m, 6H).

[0047] Example 5

[0048] A highly weather-resistant biaxially oriented PP / PE synthetic paper with a thickness of 0.20 mm, where the thickness of both the outer layer and the inner layer is 0.06 mm, and the thickness of the middle layer is 0.08 mm. The raw material composition of the outer layer is: PP: 400 g, PE: 200 g, modified anti-aging agent (prepared in Example 1): 20 g, calcium carbonate: 20 g, antibacterial agent (prepared in Example 4): 20 g, titanium dioxide: 10 g. The raw material composition of the middle layer is: PP: 300 g, PE: 200 g, calcium carbonate: 20 g, antistatic agent (AS11N antistatic agent): 20 g, titanium dioxide: 10 g. The raw materials and their ratios of the inner layer are the same as those of the outer layer.

[0049] Example 6

[0050] A highly weather-resistant biaxially oriented PP / PE synthetic paper with a thickness of 0.20 mm, where the thickness of both the outer layer and the inner layer is 0.06 mm, and the thickness of the middle layer is 0.08 mm. The raw material composition of the outer layer is: PP: 450 g, PE: 300 g, modified anti-aging agent (prepared in Example 2): 30 g, calcium carbonate: 40 g, antibacterial agent (prepared in Example 4): 30 g, titanium dioxide: 15 g. The raw material composition of the middle layer is: PP: 400 g, PE: 250 g, calcium carbonate: 40 g, antistatic agent (AS11N antistatic agent): 30 g, titanium dioxide: 15 g. The raw materials and their ratios of the inner layer are the same as those of the outer layer.

[0051] Example 7

[0052] A highly weather-resistant biaxially oriented PP / PE synthetic paper with a thickness of 0.20 mm, where the thickness of both the outer layer and the inner layer is 0.06 mm, and the thickness of the middle layer is 0.08 mm. The raw material composition of the outer layer is: PP: 500 g, PE: 400 g, modified anti-aging agent (prepared in Example 3): 50 g, calcium carbonate: 60 g, antibacterial agent (prepared in Example 4): 40 g, titanium dioxide: 20 g. The raw material composition of the middle layer is: PP: 500 g, PE: 300 g, calcium carbonate: 60 g, antistatic agent (Armostat400 antistatic agent): 40 g, titanium dioxide: 20 g. The raw materials and their ratios of the inner layer are the same as those of the outer layer.

[0053] Comparative Example 1

[0054] A highly weather-resistant biaxially oriented PP / PE synthetic paper is basically the same as Example 6, except that the modified anti-aging agent added to the outer layer and the inner layer is replaced with an equal weight of modified anti-aging agent prepared by the following method:

[0055] The preparation method of the modified anti-aging agent is basically the same as that of Example 2, except that the tetra-armed polyethylene glycol hydroxyl group in step S1 is replaced with an equal weight of pentaerythritol.

[0056] Comparative Example 2

[0057] A highly weather-resistant PP / PE biaxially oriented synthetic paper, which is basically the same as Example 6, except that the modified anti-aging agent added to the outer surface layer and the inner surface layer is replaced with an equal weight of a modified anti-aging agent prepared by the following method:

[0058] The preparation method of the modified anti-aging agent is basically the same as that of Example 2, except that the tetra-armed polyethylene glycol hydroxyl group (M W = 2000) in step S1 is replaced with an equal weight of hexa-armed polyethylene glycol hydroxyl group (M W = 2000).

[0059] Comparative Example 3

[0060] A highly weather-resistant PP / PE biaxially oriented synthetic paper, which is basically the same as Example 6, except that the modified anti-aging agent added to the outer surface layer and the inner surface layer is replaced with an equal weight of a modified anti-aging agent prepared by the following method:

[0061] The preparation method of the modified anti-aging agent is basically the same as that of Example 2, except that the tetra-armed polyethylene glycol hydroxyl group (M W = 2000) in step S1 is replaced with an equal weight of tetra-armed polyethylene glycol hydroxyl group (M W = 5000).

[0062] Comparative Example 4

[0063] A highly weather-resistant PP / PE biaxially oriented synthetic paper, which is basically the same as Example 6, except that the modified anti-aging agent added to the outer surface layer and the inner surface layer is replaced with an equal weight of antioxidant 1010.

[0064] Comparative Example 5

[0065] A highly weather-resistant PP / PE biaxially oriented synthetic paper, which is basically the same as Example 6, except that the antibacterial agent added to the outer surface layer and the inner surface layer is replaced with an equal weight of an antibacterial agent prepared by the following method:

[0066] The preparation method of the antibacterial agent is basically the same as that of Example 4, except that 1,14-diazido-3,6,9,12-tetraoxatetradecane in step A1 is replaced with an equal weight of azido-decaethylene glycol-carboxylic acid.

[0067] Comparative Example 6

[0068] A highly weather-resistant PP / PE biaxially oriented synthetic paper, which is basically the same as Example 6, except that the modified anti-aging agent added to the outer surface layer and the inner surface layer is replaced with an equal weight of an antibacterial agent prepared by the following method:

[0069] The preparation method of the antibacterial agent is basically the same as that of Example 4, except that 1,14-diazido-3,6,9,12-tetraoxatetradecane in step A1 is replaced with an equal weight of azidobenzene.

[0070] Comparative Example 7

[0071] A highly weather-resistant PP / PE biaxially oriented synthetic paper is basically the same as Example 6, except that the modified anti-aging agent added to the outer surface layer and the inner surface layer is replaced with an equal weight of an antibacterial agent prepared by the following method:

[0072] The preparation method of the antibacterial agent is basically the same as that of Example 4, except that cetyl dimethyl tertiary amine in step A2 is replaced with an equal weight of N,N-dimethyl-n-octylamine.

[0073] The highly weather-resistant PP / PE biaxially oriented synthetic papers of Examples 5-7 and Comparative Examples 1-7 are prepared by the following process:

[0074] B1: Extrude the raw materials of the outer surface layer, the intermediate layer and the inner surface layer through an extruder respectively;

[0075] B2: Extrude the raw materials of each layer extruded by the extruder through a T-shaped die head, then conduct longitudinal stretching, transverse stretching, and then cool, corona treat, and trim the edges to obtain the product;

[0076] Among them, the extrusion temperature of the raw materials of the outer surface layer and the inner surface layer is 230°C, and the extrusion temperature of the raw materials of the intermediate layer is 250°C; the preheating section temperature of the longitudinal stretching is 130°C, the stretching section temperature is 142°C, the shaping section temperature is 145°C, the longitudinal stretching ratio is 4.9, the preheating section temperature of the transverse stretching is 167°C, the stretching section temperature is 155°C, the shaping section temperature is 171°C, the transverse stretching ratio is 9 times, and the corona treatment is 34.

[0077] The PP used in the examples and comparative examples of this application is the homopolypropylene of type CJS-700 produced by China National Petroleum and Chemical Corporation; the PE grade is 5000S, produced by Sinopec Yangzi Petrochemical Co., Ltd.; the model of titanium dioxide is DR-2588, produced by Longbai Group Co., Ltd.

[0078] The highly weather-resistant PP / PE biaxially oriented synthetic papers prepared in Examples 5-7 and Comparative Examples 1-7 are subjected to ultraviolet aging tests. The test method is carried out according to GB / T 16422.3-2014 "Plastics - Methods of exposure to laboratory light sources", and the exposure conditions are carried out by the method of cycle number 1 of method A.

[0079] The high-weather-resistant PP / PE biaxially oriented synthetic papers prepared in Examples 5-7 and Comparative Examples 1-7, as well as the aged PP / PE biaxially oriented synthetic papers, were respectively subjected to tensile strength tests according to the method of GB13022-91; according to GB / T31402-2015 "Plastics - Test Method for Antibacterial Properties of Plastic Surfaces", antibacterial property tests were carried out using Escherichia coli and Staphylococcus aureus as the test strains; a wide scratch with a width of about 11 μm was made on the synthetic paper using a surgical blade; the damaged synthetic paper was placed in a constant-temperature oven at 60 °C for 24 h for repair, and then the tensile strength of the repaired sample was tested according to the GB13022-91 standard, and its self-healing rate was calculated (self-healing rate = tensile strength of the sample after repair / tensile strength of the sample before repair * 100%). The test results are shown in Table 1.

[0080] Table 1 Performance Test Table of Synthetic Paper

[0081]

[0082] As can be seen from Examples 5, 6, and 7 in Table 1, the high-weather-resistant PP / PE biaxially oriented synthetic paper prepared by the present invention has excellent anti-aging performance and antibacterial performance.

[0083] The modified anti-aging agent prepared by the present invention provides flexibility and hydrophilicity through the introduced linear segments of polyethylene glycol, has better compatibility with the synthetic paper matrix, reduces interfacial stress concentration, and improves the compatibility of the material. The cross-linking effect of the four-arm structure can provide better support performance. In addition, the four-arm structure anchors the antioxidant groups in the polymer matrix through multiple chemical bonds (disulfide bonds, amide bonds), reduces the migration and volatilization of small molecule antioxidants, and ensures long-term protection. The phenolic hydroxyl group in 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid provides hydrogen atoms to efficiently capture free radicals and terminate the oxidation reaction, and the large steric hindrance of the tert-butyl group enhances the spatial stability and prolongs the antioxidant life. A four-arm compound containing disulfide bonds is introduced to construct a dynamic reversible cross-linking network. The disulfide bonds can be broken and reformed under mechanical stress, enhancing the toughness and tensile properties of the material. Under special environments, the disulfide bonds will be reduced to mercapto groups, and the mercapto groups can capture free radicals and inhibit material aging.

[0084] The cation of the quaternary ammonium salt antibacterial agent prepared by the present invention binds to the negatively charged bacterial / fungal cell membrane through electrostatic interaction, destroys the membrane integrity, and causes the leakage of intracellular substances. The long hexadecyl chain can insert into the microbial lipid bilayer membrane, exacerbate the disintegration of the membrane structure, and enhance the bactericidal efficiency. The 1,2,3-triazole ring generated by the copper-catalyzed azide-alkyne cycloaddition reaction can bind to the synthetic paper matrix (such as polyethylene, polypropylene) through π-π stacking or hydrogen bonding, which can stabilize the antibacterial agent molecules and reduce the migration and loss of the antibacterial agent. The tetraoxatetradecane chain segment (containing multiple ether bonds) endows the antibacterial agent with flexibility, which can be better dispersed in the synthetic paper matrix and avoid local agglomeration.

[0085] The six-arm polyethylene glycol hydroxyl used in Comparative Example 2 has a higher degree of branching, and its antioxidant dispersibility is inferior to that of the four-arm antioxidant, which may lead to insufficient free radical scavenging ability in local areas.

[0086] In Comparative Example 3, a high molecular weight four-arm polyethylene glycol hydroxyl was used to prepare the antioxidant. The molecular chain of the high molecular weight four-arm polyethylene glycol hydroxyl is relatively long, and the mobility of the molecular chain segments is relatively low, resulting in poor dispersibility in the polymer matrix. This poor dispersibility will affect the interaction between the antioxidant and the matrix material and reduce the efficiency of the antioxidant.

[0087] The long chain of azido-decaethylene glycol-carboxylic acid used in Comparative Example 5 is prone to form a flexible coiled conformation, wrapping the active groups of the triazole ring or quaternary ammonium salt, hindering its contact with bacteria and reducing its antibacterial performance.

[0088] As described above, the above are only the preferred embodiments of the present invention and are not used to limit the present invention. However, for those of ordinary skill in the art, without departing from the scope of the technical solution of the present invention, some equivalent changes such as slight modifications, evolutions made by using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications, and evolutions made to the above embodiments based on the essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A highly weather-resistant biaxially oriented PP / PE synthetic paper, which consists of an outer layer, an intermediate layer and an inner layer, and is characterized in that, The outer surface layer comprises raw materials in the following parts by weight: PP: 40 - 50 parts, PE: 20 - 40 parts, modified anti-aging agent: 2 - 5 parts, calcium carbonate: 2 - 6 parts, antibacterial agent: 2 - 4 parts, titanium dioxide: 1 - 2 parts; The middle layer comprises raw materials in the following parts by weight: PP: 30 - 50 parts, PE: 20 - 30 parts, calcium carbonate: 2 - 6 parts, antistatic agent: 2 - 4 parts, titanium dioxide: 1 - 2 parts; The raw materials and their parts by weight of the inner surface layer are the same as those of the outer surface layer; The modified anti-aging agent is prepared by the following method: S1: L-homocysteine reacts with tetra-arm polyethylene glycol hydroxyl to generate tetra-arm disulfide compound; S2: The tetra-arm disulfide compound reacts with 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid under the catalysis of N,N'-dicyclohexylcarbodiimide and 1-hydroxybenzotriazole to generate the modified anti-aging agent; The antibacterial agent is prepared by the following method: A1: 1,14-diazido-3,6,9,12-tetraoxatetradecane reacts with 2-butyn-3-epoxyethane under the action of cuprous bromide to generate a triazole ring compound; A2: The triazole ring compound reacts with cetyl dimethyl tertiary amine under the action of hydrochloric acid to generate the antibacterial agent.

2. The high weather-resistant PP / PE biaxially oriented synthetic paper according to claim 1, wherein In step S1, the feeding mass ratio of L-homocysteine to tetra-arm polyethylene glycol hydroxyl is 1:(2 - 2.5).

3. A highly weather-resistant PP / PE biaxially oriented synthetic paper according to claim 1, characterized in that, In step S2, the feeding mass ratio of the tetra-arm disulfide compound to 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid is (3 - 4):

1.

4. A high weather-resistant PP / PE biaxially oriented synthetic paper according to claim 1, characterized in that, In step A1, the feeding molar ratio of 1,14-diazido-3,6,9,12-tetraoxatetradecane to 2-butyn-3-epoxyethane is 1:

2.

5. A high weather-resistant PP / PE biaxially oriented synthetic paper according to claim 1, characterized in that, In step A2, the feeding molar ratio of the triazole ring compound to cetyl dimethyl tertiary amine is 1:

2.

6. The high weather-resistant PP / PE biaxially oriented synthetic paper according to claim 1, wherein The antistatic agent is one of AS11N antistatic agent and Armostat400 antistatic agent.

7. A preparation method of the highly weather-resistant PP / PE biaxially oriented synthetic paper according to any one of claims 1-6, characterized in that, It includes the following steps: B1: Extrude the raw materials of the outer surface layer, the middle layer and the inner surface layer through an extruder respectively; B2: Extrude the raw materials of each layer extruded by the extruder through a T-shaped die head, then conduct longitudinal stretching, transverse stretching, and then cooling, corona treatment, and trimming to obtain the product; Among them, the extrusion temperature of the raw materials of the outer surface layer and the inner surface layer is 230 °C, and the extrusion temperature of the raw materials of the middle layer is 250 °C; the preheating section temperature of the longitudinal stretching is 130 °C, the stretching section temperature is 142 °C, the shaping section temperature is 145 °C, the longitudinal stretching ratio is 4.9, the preheating section temperature of the transverse stretching is 167 °C, the stretching section temperature is 155 °C, the shaping section temperature is 171 °C, the transverse stretching ratio is 9 times, and the corona treatment is 34.

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